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  • 1.
    Abali, Bilen Emek
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Institute of Mechanics, MS 2, Technische Universität Berlin, Einsteinufer 5, 10587, Berlin, Germany.
    Barchiesi, Emilio
    Additive manufacturing introduced substructure and computational determination of metamaterials parameters by means of the asymptotic homogenization2021In: Continuum Mechanics and Thermodynamics, ISSN 0935-1175, E-ISSN 1432-0959, Vol. 33, no 4, p. 993-1009Article in journal (Refereed)
    Abstract [en]

    Metamaterials exhibit materials response deviation from conventional elasticity. This phenomenon is captured by the generalized elasticity as a result of extending the theory at the expense of introducing additional parameters. These parameters are linked to internal length scales. Describing on a macroscopic level, a material possessing a substructure at a microscopic length scale calls for introducing additional constitutive parameters. Therefore, in principle, an asymptotic homogenization is feasible to determine these parameters given an accurate knowledge on the substructure. Especially in additive manufacturing, known under the infill ratio, topology optimization introduces a substructure leading to higher-order terms in mechanical response. Hence, weight reduction creates a metamaterial with an accurately known substructure. Herein, we develop a computational scheme using both scales for numerically identifying metamaterials parameters. As a specific example, we apply it on a honeycomb substructure and discuss the infill ratio. Such a computational approach is applicable to a wide class substructures and makes use of open-source codes; we make it publicly available for a transparent scientific exchange.

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  • 2.
    Abdelki, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Fused deposition modeling of API-loaded mesoporous magnesium carbonate2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the incorporation of drug loaded mesoporous magnesium carbonate as an excipient for the additive manufacturing of oral tablets by fused deposition modeling was investigated. Cinnarizine, a BCS class II drug, was loaded into the pores of the mesoporous material via a soaking method, corresponding to a drug loading of 8.68 wt%. DSC measurements on the loaded material suggested that the drug was partially crystallized after incorporation, meanwhile the XRD diffractogram implied that the drug was in a state lacking long range order. The drug loaded material was combined with two pharmaceutical polymers, Aquasolve LG and Klucel ELF, and extruded into filaments with a single screw extruder. Filaments of Klucel ELF and drug loaded Upsalite (30:70 wt% ratio) were successfully implemented for the printing oral tablets, in contrast to the Aquasolve LG based filaments which were difficult to print due to thickness variations and non-uniform material distributions. The drug content obtained by TGA suggested drug loadings of 7.71 wt% and 2.23 wt% in the drug loaded Upsalite and tablets respectively. Dissolution studies using an USP II apparatus showed a slower API-release from the tablets in comparison to the crystalline drug, most probably due to slow diffusion of drug species through the polymeric matrix. For future studies, pharmaceutical polymers with higher aqueous solubility should be investigated in order to thoroughly examine the potential of utilizing the immediate release property of Upsalite.

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  • 3.
    Abenayake, Himesha
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Additively Manufactured Rare Earth Free Permanent Magnets2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It’s well known that MnAl(C) material consists of a metastable phase (τ) with promising ferromagnetic properties, produced either by controlled cooling from the high-temperature hexagonal ε-phase or rapid cooling that freezes the ε-phase followed by low-temperature annealing. Due to the high cooling rates involved, additive manufacturing (AM) especially selective laser melting (SLM), has been identified as a possible method to retain the high-temperature ε-phase, hence containing a potential capacity to produce permanent magnets upon low-temperature annealing. Moreover, the competency of additive manufacturing to address manufacturing design complexity, material scarcity and tailored properties, yields a great opportunity to produce permanent magnets with suitable magnetic properties for complex applications. This work provides a systematic study on three main aspects; development of printing parameters for improved relative density of as-printed MnAl(C) samples; investigation of the influence of scanning strategies on the crystallographic texture of as-printed and annealed samples; investigation of the influence of annealing time and temperature on τ-phase purity and magnetic properties. It was found that laser remelting (multiple laser exposure) combined with specific scanning strategies is a promising path to enhance the relative density of as-printed samples. Some specific scanning strategies were found to be capable of retaining relatively strong crystallographic textured ε-phase in as-printed samples. Following the annealing process for ε→τ transformation, only a partial transformation of crystallographic texture was observed. Characterization of annealed samples through XRD (x-ray diffraction) and phase fractions calculations through Rietveld refinement reveals that relatively short annealing times and low temperatures result in incomplete ε→τ transformation. In addition, longer annealing times and higher temperatures surpass the complete ε→τ transformation and lead to the formation of equilibrium phases subsequently reducing the magnetic performance. Furthermore, the experimental findings demonstrated a pronounced influence of higher carbon content in the powder, resulting in improved magnetic properties.

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    Additively Manufactured Rare Earth Free Permanent Magnets
  • 4.
    Afshar, Reza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Jeanne, Simon
    Abali, Bilen Emek
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Effects of 3-D Printing Infill Density Parameter on the Mechanical Properties of PLA Polymer2023In: Sixty Shades of Generalized Continua: Dedicated to the 60th Birthday of Prof. Victor A. Eremeyev / [ed] Holm Altenbach; Arkadi Berezovski; Francesco dell'Isola; Alexey Porubov, Cham: Springer, 2023, p. 1-12Chapter in book (Refereed)
    Abstract [en]

    This study presents some results on the mechanical behavior of polylactide (PLA) material, produced using the fused deposition modeling (FDM) additive manufacturing technique. We investigate the effect of infill density on the mechanical properties of PLA specimens. We used tensile specimens, prepared according to ISO 527-2 standard, and tested them by a universal testing machine with analysis by means of digital image correlation (DIC) method. The results in terms of UTS and nominal strain at break of PLA material are presented. They demonstrate a significant impact of infill density on material behavior of PLA specimens, as expected. Yet the effect is nonlinear that is indeed valuable to understand. As infill density increases, from 10% to 100%, the nominal strain at break decreases from about 2.1% to 1.2%, respectively. In other words, the material becomes more ductile by decreasing the infill density of PLA material, which is possible to justify with an effect of the microstructure created by the infill density. There is a transition of this observed behavior, from being more ductile to more brittle, by increasing the infill density of the PLA specimens.

  • 5.
    Afshar, Reza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Jeanne, Simon
    Abali, Bilen Emek
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Nonlinear Material Modeling for Mechanical Characterization of 3-D Printed PLA Polymer With Different Infill Densities2023In: Applied Composite Materials, ISSN 0929-189X, E-ISSN 1573-4897, Vol. 30, no 3, p. 987-1001Article in journal (Refereed)
    Abstract [en]

    In additive manufacturing, also called 3-D printing, one of widely used materials is polylactide thermoplastic polymer (PLA) by means of the fused deposition modeling. For weight reduction purposes, infill density is an often used feature in slicing for 3-D printing. We aim at investigating the effect of infill density on the mechanical properties of structures. Therefore, we demonstrate how to prepare tensile specimens and test them by a universal testing machine. Results are collected by a so-called digital image correlation method. As infill density increases, from 10% to 100%, the nominal strain at break decreases from about 2.1% to 1.2%, respectively. In other words, the material becomes more ductile by decreasing the infill density of PLA material, which is possible to justify with an effect of the microstructure created by the infill density. Furthermore, we discuss a possible material model fitting all the presented results and report that a hyperelastic material model is needed for the PLA. We utilize Neo-Hookean, Mooney–Rivlin, and Yeoh models, all for different infill densities. All three models show a fairly good agreement to the experimental data. Neo-Hookean model has an advantage of only one parameter, which increases monotonously with infill density.

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  • 6.
    Algardh, Joakim Karlsson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. SP Tech Res Inst Sweden, Box 857, SE-50115 Boras, Sweden;Uppsala Univ, Dept Engn Sci, Div Appl Mat Sci, Angstrom Lab, Box 534, SE-75121 Uppsala, Sweden.
    Horn, Timothy
    North Carolina State Univ, Ctr Addit Mfg & Logist, 400 Daniels Hall,111 Lampe Dr, Raleigh, NC 27695 USA.
    West, Harvey
    North Carolina State Univ, Ctr Addit Mfg & Logist, 400 Daniels Hall,111 Lampe Dr, Raleigh, NC 27695 USA.
    Aman, Ronald
    North Carolina State Univ, Ctr Addit Mfg & Logist, 400 Daniels Hall,111 Lampe Dr, Raleigh, NC 27695 USA.
    Snis, Anders
    Arcam AB, Krokslatts Fabriker 27A, SE-43137 Molndal, Sweden.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lausmaa, Jukka
    SP Tech Res Inst Sweden, Box 857, SE-50115 Boras, Sweden.
    Harrysson, Ola
    North Carolina State Univ, Ctr Addit Mfg & Logist, 400 Daniels Hall,111 Lampe Dr, Raleigh, NC 27695 USA.
    Thickness dependency of mechanical properties for thin-walled titanium parts manufactured by Electron Beam Melting (EBM)(R)2016In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 12, p. 45-50Article in journal (Refereed)
    Abstract [en]

    Metal powder bed additive manufacturing technologies, such as the Electron Beam Melting process, facilitate a high degree of geometric flexibility and have been demonstrated as useful production techniques for metallic parts. However, the EBM process is typically associated with lower resolutions and higher surface roughness compared to similar laser-based powder bed metal processes. In part, this difference is related to the larger powder size distribution and thicker layers normally used. As part of an effort to improve the resolution and surface roughness of EBM fabricated components, this study investigates the feasibility of fabricating components with a smaller powder size fraction and layer thickness (similar to laser based processes). The surface morphology, microstructure and tensile properties of the produced samples were evaluated. The findings indicate that microstructure is dependent on wall-thickness and that, for thin walled structures, tensile properties can become dominated by variations in surface roughness. (C) 2016 Elsevier B.V. All rights reserved.

  • 7.
    Amaralapudi Bala Vardha Raju, Rahul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Thammisetty, Raja Surya Mahesh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Material selection and topology optimization of a shift fork for metal 3D printing2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In collaboration with Kongsberg Automotive, the thesis focuses on material selection and redesigning the shift fork for additive manufacturing using topology optimization. The shift fork is a component in the gear shifting mechanism in the automotive industry. The current shift fork at Kongsberg is manufactured from aluminum using die-casting. This design and material do not withstand huge dynamic loads in commercial vehicles. The material to withstand the loading conditions and is widely available across powder manufacturers is selected using the weighted properties method. The topology optimization of the design resulted in a 50 % reduction in mass. The shift fork's two legs undergo uneven load distribution due to eccentricity. The optimized models are simulated using Finite Element Analysis to validate the design. The optimized design is obtained such that the difference in displacement between both legs is within 50 %. Numerous metal powder manufacturers and 3D printing service providers were contacted to understand the current additive manufacturing market.

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  • 8.
    Appelqvist, Rickard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Dabram, Sam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Zetterström, Joel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Möjligheter och hinder för implementeringen av additiv tillverkning i svensk sjukvård: En TOE-baserad studie av faktorer som påverkar implementeringen2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing is a manufacturing process where material is added layer by layer to create an object, enabling the production of products with complex geometries. Additive manufacturing is frequently used in healthcare today and can streamline processes and create added value for patients. The market for additive manufacturing in healthcare is expected to grow significantly. Despite this, the implementation rate in Swedish healthcare is currently low due to several barriers that hinder its use. The purpose of this work is to understand the opportunities and challenges of additive manufacturing and what is required to increase its use in healthcare. The study is conducted using a qualitative method in the form of semi-structured interviews with researchers and company representatives with experience and knowledge in additive manufacturing. The results presented in the report show that cost, lead time, medical regulations, and procurement are of great importance in the implementation of additive manufacturing in Swedish healthcare. The analysis is conducted using the Technology-Organization-Environment framework to identify themes in the collected data. The conclusions of the work emphasize the importance of addressing regulatory barriers and designing appropriate procurement processes to facilitate the implementation of additive manufacturing in healthcare. Furthermore, there is a need for a deeper cost analysis of additive manufacturing for medical applications to better understand the economic aspects and identify areas where the technology is most profitable and effective. The study also indicates that a more comprehensive understanding could be achieved by including perspectives from healthcare professionals and patients.

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  • 9.
    Aung, Soe Ko Ko
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Sakon Nakhon Rajabhat Univ, Res & Dev Inst, Ctr Excellence Alternat Energy, Dept Phys, Fac Sci & Technol, Opt Res Lab, Sakon Nakhon 47000, Thailand.
    Vijayan, Anuja
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Seetawan, Tosawat
    Sakon Nakhon Rajabhat Univ, Res & Dev Inst, Ctr Excellence Alternat Energy, Dept Phys,Fac Sci & Technol,Opt Res Lab, Sakon Nakhon 47000, Thailand..
    Enhanced Thermal Stability of Low-Temperature Processed Carbon-Based Perovskite Solar Cells by a Combined Antisolvent/Polymer Deposition Method2022In: Energy Technology, ISSN 2194-4288, Vol. 10, no 8, article id 2200177Article in journal (Refereed)
    Abstract [en]

    Low-temperature processed carbon-based perovskite solar cells have received great attention due to low-cost, high stability, and simple preparation processes that can be employed in large-scale manufacturing. Carbon paste is deposited by techniques such as doctor blading or screen printing. However, solvents from this paste can damage the perovskite or underlying layers resulting in poor performance of solar cells. Furthermore, carbon is not an ideal hole-selective contact. To overcome these issues, the antisolvent treatment is combined with the deposition of a polymeric hole conductor. Specifically, poly(3-hexylthiophene) (P3HT), added into the chlorobenzene antisolvent, improves perovskite morphology and reduces interfacial carrier recombination. As a result, the power conversion efficiency (PCE) of solar cells with the device structure SnO2/MAPbI3/P3HT/carbon increases to 12.16% from 10.6% of pristine devices without P3HT, using pure antisolvent. For poly(triarylamine) hole conductor in the same method, PCE improves only slightly to 11.1%. After 260 h of thermal stress at 82 °C, the P3HT-additive devices improve PCE up to 13.2% in air and maintain 91% of their initial efficiency over 800 h.

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  • 10. Aydin, Gokhan
    et al.
    Sarar, B. Cagri
    Yildizdag, M. Erden
    Abali, Bilen Emek
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Investigating infill density and pattern effects in additive manufacturing by characterizing metamaterials along the strain-gradient theory2022In: Mathematics and mechanics of solids, ISSN 1081-2865, E-ISSN 1741-3028, Vol. 27, no 10, p. 2002-2016Article in journal (Refereed)
    Abstract [en]

    Infill density used in additive manufacturing incorporates a structural response change in the structure. Infill pattern creates a microstructure that affects the mechanical performance as well. Whenever the length ratio of microstructure to geometry converges to one, metamaterials emerge and the strain-gradient theory is an adequate model to predict metamaterials response. All metamaterial parameters are determined by an asymptotic homogenization, and we investigate the effects of infill density and pattern on these parameters. In order to illuminate the role of infill characteristics on the strain-gradient parameters, an in-depth numerical investigation is presented for one, widely used case in three-dimensional (3D) printers, rectangular grid.

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  • 11.
    Bae, Kichang
    et al.
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Shin, Dongmin
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Lee, Jonghun
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Kim, Seohan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Lee, Wookjin
    Pusan Natl Univ, Sch Mat Sci & Engn, Busan 46241, South Korea..
    Jo, Ilguk
    Dong Eui Univ, Adv Mat Engn, Busan 47340, South Korea..
    Lee, Junghoon
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Corrosion Resistance of Laser Powder Bed Fused AISI 316L Stainless Steel and Effect of Direct Annealing2022In: Materials, E-ISSN 1996-1944, Vol. 15, no 18, article id 6336Article in journal (Refereed)
    Abstract [en]

    Alloy parts produced by an additive manufacturing method with rapid heat transfer from fast melting and solidification have different microstructures, characteristics, and performances compared with materials made by the conventional process. In this study, the corrosion and oxidation resistance of SS316L, which was prepared by the powder bed fusion process, was compared with those of cold-rolled SS316L. Additionally, the surface oxide film on stainless steel was thoroughly assessed since the film has the greatest influence on the corrosion and oxidation resistance. The effect of heat treatment on corrosion and oxidation resistance of SS316L fabricated by additive manufacturing was investigated. The SS316L has a microstructure formed by sub-grain cells, in which locally concentrated alloying elements form a stable passive film. As a result, it has a higher level of corrosion resistance and oxidation resistance than conventional cold-rolled materials. However, it was confirmed that the sub-grain cell was removed by heat treatment, which resulted in the degradation of corrosion and oxidation resistance.

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  • 12.
    Beer, Netta
    et al.
    Univ Copenhagen, Dept Pharm, Copenhagen, Denmark..
    Hegger, Ingrid
    Natl Inst Publ Hlth & Environm RIVM, Ctr Hlth Protect, Bilthoven, Netherlands..
    Kaae, Susanne
    Univ Copenhagen, Dept Pharm, Copenhagen, Denmark..
    De Bruin, Marie Louise
    Natl Inst Publ Hlth & Environm RIVM, Ctr Hlth Protect, Bilthoven, Netherlands.;Univ Copenhagen, Copenhagen Ctr Regulatory Sci, Dept Pharm, Copenhagen, Denmark. Univ Utrecht, Utrecht Inst Pharmaceut Sci, Div Pharmacoepidemiol & Clin Pharmacol, Utrecht, Netherlands..
    Genina, Natalja
    Univ Copenhagen, Dept Pharm, Copenhagen, Denmark..
    Leonardo Alves, Teresa
    Natl Inst Publ Hlth & Environm RIVM, Ctr Hlth Protect, Bilthoven, Netherlands..
    Hoebert, Joelle
    Natl Inst Publ Hlth & Environm RIVM, Ctr Hlth Protect, Bilthoven, Netherlands..
    Kälvemark Sporrong, Sofia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Univ Copenhagen, Dept Pharm, Copenhagen, Denmark.
    Scenarios for 3D printing of personalized medicines: A case study2021In: Exploratory Research in Clinical and Social Pharmacy, E-ISSN 2667-2766, Vol. 4, article id 100073Article in journal (Refereed)
    Abstract [en]

    Background

    3D printing is a promising new technology for medicines' production. It employs additive manufacturing techniques, and is ideal for producing personalized medicines (e.g., patient-tailored dose, dosage form, drug release kinetics).

    Objective

    To investigate how 3D printing technologies can be implemented in a European pharmaceutical system, by suggesting different scenarios and assessing aspects that could affect its implementation.

    Method

    Qualitative, semi-structured interviews were conducted with key stakeholders (e.g., from ministry, authorities, research organizations, pharmacies) in the Netherlands to elicit perspectives on 3D printing of personalized medicines. The Netherlands were chosen since it has a strong tradition in compounding. Five general scenarios were investigated: placing the 3D printers in industry, community pharmacies, hospital pharmacies, compounding facilities, and in patients' homes. Content analysis was used, building on verbatim transcripts.

    Results

    Fifteen stakeholders were interviewed. Regulatory, economic, ethical and organizational challenges were identified to varying degrees in the different scenarios. The industry and home scenarios were associated with the most challenges, hospital pharmacies and compounding facilities with the least. Other important aspects identified were the role of community pharmacies, and who should design the tablets to be printed.

    Conclusion

    All potential scenarios for 3D printing of personalized medicines include challenges. These should be taken into account when pursuing the use of 3D printing of medicine.

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  • 13.
    Benatto, L.
    et al.
    Univ Fed Parana, Dept Phys, CP 19044, BR-81531980 Curitiba, Parana, Brazil.
    Govatski, J. A.
    Univ Fed Parana, Dept Phys, CP 19044, BR-81531980 Curitiba, Parana, Brazil.
    de Moraes, C. A. M.
    Univ Fed Parana, Dept Phys, CP 19044, BR-81531980 Curitiba, Parana, Brazil.
    Gouvea, C. P.
    Pontifical Catholic Univ Rio de Janeiro, Dept Phys, BR-22453900 Rio De Janeiro, RJ, Brazil; Natl Inst Metrol Qual & Technol, Mat Metrol Div, BR-25250020 Duque De Caxias, RJ, Brazil.
    Avila, H. C.
    Pontifical Catholic Univ Rio de Janeiro, Dept Phys, BR-22453900 Rio De Janeiro, RJ, Brazil; Univ Atlantico, Programa Fis, Km 7 Via Puerto Colombia, Puerto Colombia 081001, Atlantico, Colombia.
    Marchiori, Cleber F. N.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Oliveira, C. K. B. Q. M.
    Univ Fed Parana, Dept Phys, CP 19044, BR-81531980 Curitiba, Parana, Brazil.
    Cremona, M.
    Pontifical Catholic Univ Rio de Janeiro, Dept Phys, BR-22453900 Rio De Janeiro, RJ, Brazil.
    Koehler, M.
    Univ Fed Parana, Dept Phys, CP 19044, BR-81531980 Curitiba, Parana, Brazil.
    Roman, L. S.
    Univ Fed Parana, Dept Phys, CP 19044, BR-81531980 Curitiba, Parana, Brazil.
    Understanding the effect of solvent additive in polymeric thin film: turning a bilayer into a bulk heterojunction-like photovoltaic device2020In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 53, no 36, article id 365101Article in journal (Refereed)
    Abstract [en]

    Here we report the effect of an additive solvent, 1,8-diiodooctane (DIO), on the performance of a bilayer organic photovoltaic device in which the active layer comprises poly[2,7-(9,9-bis(2 ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) as the electron donor material and C60 as the electron acceptor material. We observed that when the donor layer was treated with 1% of DIO the power conversion efficiency (PCE) of the device increased by 138.4% in relation to the device with an untreated donor layer, and 21.3% in relation to the device containing a donor layer submitted to thermal annealing. The main effects that lead to this increase in PCE are the large interfacial area between donor and acceptor materials and the improved conductivity at low voltages. The increase in polymer surface roughness leads to a more effective PSiF-DBT/C60 interface for exciton dissociation. This effect, as well as the increase in the conductivity, raised the short circuit current density (JSC) to 13.89 mA cm−2 and the PCE to 4.84%. Our conclusions are supported by morphological analysis, chemical cross-sectional evaluations with advanced microscopy techniques, charge mobility measurements, as well as by theoretical simulations of the devices in which the changes on the donor/acceptor interfacial area were considered. The outcomes suggest that solvent additives could be an alternative treatment to replace the thermal annealing, which imposes further difficulties in performing lab-to-manufacturing upscaling.

  • 14.
    Benn, Felix
    et al.
    School of Mechanical and Aerospace Engineering, Queens University Belfast, Belfast, United Kingdom..
    D'Elia, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    van Gaalen, Kerstin
    Meotec GmbH, Aachen, Germany.; Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland..
    Li, Muzi
    IMDEA Materials Institute, Madrid, Spain..
    Malinov, Savko
    School of Mechanical and Aerospace Engineering, Queens University Belfast, Belfast, United Kingdom..
    Kopp, Alexander
    Meotec GmbH, Aachen, Germany..
    Printability, mechanical and degradation properties of Mg-(x)Zn elemental powder mixes processed by laser powder bed fusion2022In: Additive Manufacturing Letters, ISSN 2772-3690, Vol. 2, article id 100025Article in journal (Refereed)
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  • 15.
    Berglund, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Framtagning av ny bärare för kassettöverdelar2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Fiomi Diagnostics AB manufactures and develops point of care cassettes for bloodsamples to determine risk of myocardial infarction and heart failure for use within thehealthcare sector. The cassette contains of three main parts; top, bottom and a plasticchip. The bottom parts are delivered directly from the supplier to the assembly linewhile the top part has to be prepared with a membrane for blood separation byultrasonic welding before it can be sent to the assembly line.

    At present the top parts are provided with the membranes a floor below theassembly line and therefore have to be transported by carriers to the assembly line.These carriers are currently designed as large plates (400 x 600 mm) with a capacityof 120 top parts, but they are space consuming at the ultrasonic welder as well at theassembly line.To solve this lack of space the operators often place the platesdiagonally behind themselves where room is available. This causes ergonomicproblems due to the many twists of the upper body conducted at both processes.

    To solve the ergonomic problems this thesis work were initiated to develop a newmore agile carrier between the two processes. During the thesis work TRIZ wereused to trigger creative concepts, choose among them and combine the good ideasfrom different concepts. After the conceptual phase different manufacturing methodswere explored. To be certain that the concept could be manufactured by specificmanufacturing process different manufactures were contacted to help out with whatwould make the concept suitable for the specific method. The manufacturing methodsexamined were: injection molding, plastic and aluminum extrusion, vacuum molding,additive manufacturing and sheet metal bending.

    Prototypes of the three best concepts were created by 3D-printing to be evaluatedby the operators whom in the future might be using the new carriers. Complementedwith an evaluation of the carriers economic and performance data, a recommendationof which carrier should be selected were concluded.

    The result was a carrier manufactured by sheet metal bending with a pattern cut outwhich allows for the top parts to hang in the carrier. The design has a capacity of 60top parts which is half of the current carrier, but with a base area of a sixth of thecurrent carrier gives the new design an increase in surface efficiency by 300 %. Due tothe low order size the sheet metal alternative was the cheapest alternative.

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  • 16.
    Bergman, Henrik Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Increasing the Writing Resolution for Electro-hydrodynamic 3D-Printing: by Active Steering of e-jet2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing has grown considerably during the last couple of decades, whether it comes to the printing of metal structure or living cells. Additive manufacturing techniques relays on the successive addition of material to create the wanted structure. Among the diversity of these many printing techniques, electrohydrodynamic 3D-printing is of particular interest, as the technique has a promising outlook for high-resolution printing on the microscale. The technique is compatible with a myriad of thermoplastics, but its writing resolution is limited due to the inherent affect the manufacturing process has on the material. Electrostatic forces between already deposited fibres and the fibre in light affect the final position of printed fibre. This thesis evaluates the possibility to increase the writing resolution in melt electrohydrodynamic 3D printing by a closed-loop feedback system. Components were built and added to an already existing printing setup to implement in-situ measurements of the fibres position as well as active electrostatic guiding of the fibre. The setup consisted of a camera that determined the position of the fibre; the position was then used in a PID controller to calculate an appropriate potential. The potential was forwarded to a high voltage amplifier, connected to a steering electrode, mounted in the vicinity of the jet. The setup built for one-dimensional steering of the fibre improved the printing accuracy by ten times through suppressing the repulsive/attractive forces, where the process variable of the PID controller was measured. However, the precision decreased roughly four times as it was deposited on the substrate. The limitations of the system have been evaluated, and possible improvements for the two-dimensional control of the fibre are further discussed.

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  • 17.
    Bjelke, Carl-Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Additive Manufacturing for Volume Production: A case study in supply chain benefits of AM implementation2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing was first introduced in the 80s and has ever since been used as a tool for rapid prototyping. Its flexible manufacturing characteristics makes it optimal for creating complex geometries in one manufacturing process, eliminating assembly time for several individual parts. Additive manufacturing has yet not been introduced as a tool for volume manufacturing. This has historically been because of quality concerns in printing as well as printing speed. Recent technique developments mitigated these issues and the case for additive manufacturing in volume production is revaluated in a context of supply chain benefits in this study. 

    The primary data was collected using interviews at the case company. Additionally official company document was used as empirical data, in conjunction with a scientific literature review to achieve data triangulation.  The results were then analyzed using a system dynamics approach. Finally, a conceptual solution of a present-day supply chain setup with additive manufacturing integration is presented.

    The analysis resulted in a solution where additive manufacturing capabilities were integrated at or near the location of the outsourced production and assembly services. This can act as a production buffer to mitigate issues related to variability in shipping. This technique can be implemented without significant alterations to the present supply chain practices. However, in order to reap the full benefits, i.e., gaining flexibility in production as greater design freedom, of using additive manufacturing, the design process must be adapted for the additive manufacturing technique. 

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  • 18.
    Borg, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Automatization of de-powdering process for binder jetting technology2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing has gained considerable attention in recent years due to its capabilities of producing complex parts with tailormade mechanical properties. Because of its infancy state, additive manufacturing production chains are seldom optimized to the same extent as conventional manufacturing techniques. Companies with additive manufacturing production sitesusing powder as a building material often find themselves devoting a lot of resources towards depowdering, a post processing step that has potential of being a significant bottleneck.The purpose of this master thesis was to develop a de-powdering system that would function automatically, relieving operators from performing the process step manually. The following work has been conducted at Sandvik in Sandviken at the department for additive manufacturing.Results were acquired with high credibility due to a mixture of qualitative and quantitative gathering techniques that supplemented each other. Together with a literature review, empirical data gave rise to the possibility of developing a new de-powdering system for binder jetting technology.Optimization of the system indicated that larger inlets produced a higher removal efficiency. This was later confirmed with computational fluid dynamics, where smaller nozzles created a more turbulent air flow, making it difficult for powder particles to exit the system. Though final trials with green bodies revealed that the system, in its current state, did not have the capabilities of replacing manual de-powdering completely, it certainly displayed how efficient it can be with further development. 

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  • 19.
    Brantnell, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Salelkar, Lakshmi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Linné, Åse
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Schliemann, Marvin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Temiz, Serdar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Lindahl, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Testbed for Material and Additive Manufacturing: Needs Analysis and Benchmarking2022Report (Other academic)
    Abstract [en]

    The manufacturing industry is facing a radical transformation due to digitization of production, demands on sustainable production, and possibilities of additive manufacturing (AM). AM, an alternative to mechanical manufacturing, provides several benefits such as rapid prototyping and low environmental impact. AM offers an opportunity for companies to improve their competitive conditions and value offerings while contributing to sustainable development. However, AM also poses challenges for companies, especially for small- and medium-sized enterprises (SMEs) as these companies often lack the financial resources and expertise to use new manufacturing methods. Testbeds are one way to support companies and accelerate change towards AM. 

    This report builds on previous investigations concerning testbeds and AM and explores the possibilities and conditions to establish a testbed with a focus on AM in the Uppsala Region. This report builds on site visits and interviews with ten existing testbeds and site visits and interviews with 14 companies. The testbeds were spread around the country, and the companies were centered on the Uppsala Region.

    The findings are divided into two clusters: companies and testbeds. Altogether, nine companies either manufactured AM components or AM powder. All 14 companies had experience using AM, which is a clear indication that all these companies are early adopters or potential early adopters of AM. The companies that did not use AM (non-adopters) considered AM to be a promising technology but believed that AM did not fit with their current operations. The non-adopters believed AM was best suited for R&D, where proof of concepts and prototypes are developed and explored, which implies low technical maturity. Most the companies saw AM as a possibility for their operations. Non-adopters perceived AM as a possible complement to traditional manufacturing. Several non-adopters noted that they would adopt AM if customers requested it. Many non-adopters had difficulties identifying a business case for AM. In total, seven of the 14 companies had no experience with testbeds. Many companies envisioned a physical facility placed preferably near Uppsala and considered that a testbed could be helpful with material development. Many of the companies preferred a pay per use price model for the testbed. Furthermore, many of the companies were not willing to invest in creation of a testbed, but they were interested in using a testbed if available.

    Of the ten testbeds investigated, six integrate AM in their operations. Irrespective of whether the testbeds used AM, the establishment of the testbeds can be seen as an incremental trial and error process, which takes time and often starts with common projects. The path to establishing a formal testbed varied across the testbeds, but all the testbeds were developed based on the needs of their stakeholders such as academia or industry. Most of the testbeds needed to secure financing. Many of the testbeds initially received public funding, and these funds were used to establish facilities and set up an organization. The main challenge lies in having long-term financing covering running costs of rent, maintenance, human resources, and continuous investments. In addition to pay per use fees, a base funding originating (e.g., from member organizations) is crucial for long-term survival. The testbeds had difficulties estimating capacity use of the facilities, but all concluded the use is not yet 100%, so there are possibilities to increase the use of the facilities. It is clear that the testbeds need to define the value of the testbeds from a user perspective. Many testbeds experience challenges attracting SMEs irrespective of whether they focus on AM.

    Based on the investigation, this report formulates one key recommendation: Create a joint testbed building on the existing AM competences and facilities in Uppsala by combining existing testbeds (AM@Ångström and U-PRINT) into one testbed.

    That is, it is not viable to establish a totally new physical testbed as this would require several years of development and high investment costs. There are three main opportunities concerning this recommendation: 1) added value for Uppsala University and external users; 2) new user groups, and 3) specialization on life sciences.

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  • 20.
    Brantnell, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Healthcare Sciences and e-Health.
    Sandgren, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Wolff, Annette
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Temiz, Serdar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Barriers and facilitators to the implementation of additive manufacturing in cardiology: A qualitative study2022In: Annals of 3D Printed Medicine, ISSN 2666-9641, Vol. 7, article id 100067Article in journal (Refereed)
    Abstract [en]

    Background: Additive manufacturing (AM) is a fast-developing technology with possible applications in car-diology. Existing research has identified two general factors that can influence implementing AM in cardiol-ogy: economics and technology.

    Objective: In this study we aimed to identify barriers and facilitators to implementing AM in cardiology.

    Methods: We conducted a multiple case study of two Swedish cardiac surgery departments representingimplementers and non-implementers of AM. We interviewed key stakeholders (n=8) who had been or wereinvolved in implementing AM in cardiology or AM in general at the hospitals: cardiologists, physicians work-ing with AM but not specialized in cardiology such as radiologists, company representatives, and individualsinvolved in the 3D-printing facilities. A combination of an inductive and deductive approach was used to ana-lyze the interviews.

    Results: Several barriers and facilitators influenced implementing AM in cardiology. Most barriers (n=4) wererelated to innovation factors, whereas most facilitators (n=4) were related to healthcare professionals. No barriers and facilitators were related to patients.

    Conclusion: Our findings show that AM in cardiology is in its very early phases in both hospitals and mostlythe work of a few individuals. In the two hospitals studied, there were some unique differences in terms ofbarriers that could explain the low level of implementation. These barriers could be important to addresswhen supporting implementation of AM at hospitals where AM use is still low.

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  • 21.
    Bremler, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Fatigue and microstructural study of a 316L austenitic stainless steel marine component produced by Wire Arc Additive Manufacturing (WAAM)2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study, the fatigue- and fracture properties and microstructure of a marine component of austenitic stainless steel 316L manufactured with the novel method Wire Arc Additive Manufacturing were investigated and compared with data from literature. The purpose was to find a critical flaw size in the material related to its fatigue life.

    It was done by studying the microstructure and interpreting fatigue- and mechanical data for the marine component in empirical models related to the fatigue- and fracture properties. Fracture properties were approximated to estimate fatigue life and critical flaw size. Fatigue limit and fatigue threshold were based on hardness test data, fracture toughness, and FADs on Charpy-V impact test data.

    The material manufactured with Wire Arc Additive Manufacturing had superior fatigue properties than cast and rolled equivalents and performed better in the fatigue test than recommendations for austenitic stainless steel in a seawater environment from the British Standard 7910:2019. Due to the conservative model's fatigue limit and fatigue threshold, the results are conservative. The reason for that could be the crack closure properties of the material. The results for fracture toughness are lower than the literature data. This is most likely due to conservative models based on Charpy-V impact test data.

    The most important properties of the fatigue life are the fatigue limit and the fatigue threshold due to their relationship with crack growth. Testing the lifetime of the component in seawater is complex and time-consuming due to the corrosion and the need for low test frequency.

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  • 22. Brown, Toby D
    et al.
    Edin, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
    Detta, Nicola
    Skelton, Anthony D
    Hutmacher, Dietmar W
    Dalton, Paul D
    Melt electrospinning of poly(ε-caprolactone) scaffolds: phenomenological observations associated with collection and direct writing.2014In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 45Article in journal (Refereed)
    Abstract [en]

    Melt electrospinning and its additive manufacturing analogue, melt electrospinning writing (MEW), are two processes which can produce porous materials for applications where solvent toxicity and accumulation in solution electrospinning are problematic. This study explores the melt electrospinning of poly(ε-caprolactone) (PCL) scaffolds, specifically for applications in tissue engineering. The research described here aims to inform researchers interested in melt electrospinning about technical aspects of the process. This includes rapid fiber characterization using glass microscope slides, allowing influential processing parameters on fiber morphology to be assessed, as well as observed fiber collection phenomena on different collector substrates. The distribution and alignment of melt electrospun PCL fibers can be controlled to a certain degree using patterned collectors to create large numbers of scaffolds with shaped macroporous architectures. However, the buildup of residual charge in the collected fibers limits the achievable thickness of the porous template through such scaffolds. One challenge identified for MEW is the ability to control charge buildup so that fibers can be placed accurately in close proximity, and in many centimeter heights. The scale and size of scaffolds produced using MEW, however, indicate that this emerging process will fill a technological niche in biofabrication.

  • 23.
    Bugurcu, Alan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Investigation on how additive manufacturing with post-processing can be used to realize micronozzles2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This is predominantly a qualitative study on the manufacturing of micronozzles with an additive manufacturing (AM) technique, namely the laser-powered powder bed fusion (PBF-LB). 

    Manufacturing of micronozzles with standard microelectromechanical system technology often results in 2.5-D or close to 3-D structures and does not yield a fully rotationally symmetric nozzle. For this reason, AM can be a better solution. However, the structures obtained with PBF-LB exhibit very rough surfaces which will impair the performance of the micronozzle. To improve the surface finish electropolishing was performed on the interior walls. 

    Given the shape and the scale of the components, uniformity of the polishing is a challenge, calling for an inventive electrode configuration and electrolyte feed solution. The approach was to integrate an electrode on the inside of the converging part of the nozzle, to serve as a cathode for the electropolishing, already in the process, and to make the nozzle itself the vital part of the fluidic system. 

    With this, titanium micronozzles were manufactured with throat diameters varying between 300 and 800 μm. With the resolution of the used AM technique, it was possible to integrate the internal electrode in the micronozzles with a designed throat diameter down to 600 μm. Below this, the anode, and cathode, sometimes made contact short-circuiting the cell. Profilometry showed a decrease of the average surface roughness (𝑅𝑅𝑎𝑎) with 15-60 % for the electropolished micronozzles. The Schlieren imaging showed an exhaust that followed the throat’s axial direction and also demonstrated pressure disks and, hence, a supersonic jet exhaust. This study has shown that AM is a viable choice for manufacturing of rotationally symmetric micronozzles, and that electropolishing could be used to decrease the surface roughness on their inside uniformly with the integration of a cathode. 

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  • 24.
    Bång, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Additiv teknik, ett hjälpmedel i produktutvecklingen2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis has been carried out in collaboration with Maximatecc AB. In their office in Alfta they work with product development of both hardware andsoftware for various kinds of products including display computers and controllers for different kinds of equipment. In the product development process its common that several different kinds of additive manufactured (3D-printed) prototypes are ordered from an external company.

    The main objective with this thesis is to increase the knowledge about different kinds of additive manufacturing technologies that exists and are relevant for the company and how and why prototypes are important for the product development process. It will also with the help of interviews and observations at the company investigate how additive technologies are used today at Maximatecc and what other needs of the technology that exists. By doing so it will be determined if there is a need to buy an3D-printer or continue to order the service from an external company. A practical part of this thesis is to see if a component manufactured with different kinds of additive technologies is suitable to work as a substitute to an injection molded part in a product during the prototype phase.

    There could be a need for to buy a 3D-printer that uses FDM (fused depositionmodelling) -technology but it will not replace the need to buy in additive manufactured prototypes from an external company. This is because of the different kinds of desired attributes of the prototypes used during the product development process and the advantages and disadvantages of the different kinds of technologies.

    It was also concluded that components manufactured with additive technology could be used as a part in a functional product during the prototype phase. This could be used to send fully working prototypes to customers early in the product development process.

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  • 25.
    Cannataro, Loris
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Understanding Proximity in Research Consortia: A case study of proximity dimensions within the AddLife Competence Centre2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today’s knowledge creation process has become extremely complex. On the one hand, technological innovation increasingly requires the use of complementary expertise from several apparently unrelated fields. On the other, the magnitude of the challenges that research and development present often require a large amount of resources that single actors can hardly achieve by themselves. For these reasons, the popularity of collaborative research has increased greatly in recent years. Among the many forms of collaborative research adopted today, research consortia are the most used.

    Given the steady increase of this trend, it has become important to understand the dynamics at play in research consortia. In particular, it is crucial to understand how participants interact with each other and the implication of such interactions on the success of a consortium’s outcome. The following study utilises a proximity-based framework to the single case study of the AddLife Competence Centre, an Uppsala University based R&D consortium for the development of Additive Manufacturing technology applied to Life Science. The data was collected by conducting eleven semi-structured interviews of AddLife participants.

    This study begins by presenting an overview of the literature on collaborative network, collaborative research and proximity. It moves onto analysing the interactions of actors in AddLife as a triple helix arrangement. Next, linkages between actors are expressed in terms of organisational, cognitive and social proximity. The analysis is discussed and presented as follows: uncertainty and discrepancies can lower organisational proximity, while the lack of goals alignment can lower cognitive proximity. High social proximity can mitigate the effects of both, especially in case of opportunistic behaviour. Acting on these three proximity dimensions should be prioritised over other proximity trade-offs.

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  • 26.
    Cantoni, Federico
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Maher, Daniel
    National Centre for Nano Fabrication and Characterization (DTU Nanolab), Technical University of Denmark.
    Bosler, Eugenia
    Institute of Micro and Precision Devices, Technical University of Berlin.
    Kühne, Stefan
    Institute of Micro and Precision Devices, Technical University of Berlin.
    Barbe, Laurent
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Oberschmidt, Dirk
    Institute of Micro and Precision Devices, Technical University of Berlin.
    Marquette, Christophe
    3d.FAB, Univ Lyon, Universit´e Lyon1, CNRS, INSA, CPE-Lyon, ICBMS.
    Taboryski, Rafael
    National Centre for Nano Fabrication and Characterization (DTU Nanolab), Technical University of Denmark.
    Tenje, Maria
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Bunea, Ada-Ioana
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Uppsala University, Science for Life Laboratory, SciLifeLab. National Centre for Nano Fabrication and Characterization (DTU Nanolab), Technical University of Denmark.
    Round-robin testing of commercial two-photon polymerization 3D printers2023In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 76, article id 103761Article in journal (Refereed)
    Abstract [en]

    Since its introduction in the 1980s, 3D printing has advanced as a versatile and reliable tool with applications in different fields. Among the available 3D printing techniques, two-photon polymerization is regarded as one of the most promising technologies for microscale printing due to its ability to combine a high printing fidelity down to submicron scale with free-form structure design. Recently, the technology has been enhanced through the implementation of faster laser scanning strategies, as well as the development of new photoresists. This paves the way for a wide range of applications, which has resulted in an increasing number of available commercial systems. This work aims to provide an overview of the technology capability by comparing three commercial systems in a round-robin test. To cover a wide range of applications, six test structures with distinct features were designed, covering various aspects of interest, from single material objects with sub-micron feature sizes up to multi-material millimeter-sized objects. Application-specific structures were printed to evaluate surface roughness and the stitching capability of the printers. Moreover, the ability to generate free-hanging structures and complex surfaces required for cell scaffolds and microfluidic platform fabrication was quantitatively investigated. Finally, the influence of the numerical aperture of the fabrication objective on the printing quality was assessed. All three printers successfully fabricated samples comprising various three-dimensional features and achieved submicron resolution and feature sizes, demonstrating the versatility and precision of two-photon polymerization direct laser writing. Our study will facilitate the understanding of the technology maturity level, while highlighting specific aspects that characterize each of the investigated systems.

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  • 27. Chao, Meie
    et al.
    Genina, Natalja
    Beer, Netta
    Kälvemark Sporrong, Sofia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark.
    Data-enriched edible pharmaceuticals (DEEPs): Patients' preferences, perceptions, and acceptability of new dosage forms and their digital aspects – An interview study2022In: Exploratory Research in Clinical and Social Pharmacy, E-ISSN 2667-2766, Vol. 6, article id 100141Article in journal (Refereed)
    Abstract [en]

    Background

    In the field of pharmaceuticals, there is a shift away from the traditional “one-size-fits-all” concept to a more patient-centered one. A potential approach to obtain personalized medicine is with printed Data-Enriched Edible Pharmaceuticals (DEEPs). DEEPs that are printed in the pattern of QR codes contain both the patient-tailored dose and data that can be used to give patients personalized drug information and combat counterfeit medicines.

    Objectives

    The study aims to explore patients' preferences, perceptions, and acceptability of DEEPs, and the digital aspects of them.

    Methods

    Thirteen participants, living in Denmark, were interviewed twice using a semi-structured approach. Interviews were conducted face-to-face or via video calls. The interviews were transcribed, translated, and analyzed using thematic coding analysis.

    Results

    The participants found it useful to participate in the design of their own medicine. The orodispersible nature of DEEPs and the possibility to select color, embedded images, flavors, and physical dimensions of DEEPs were considered beneficial for patients' adherence. Patients' personal preferences, convenience, and aesthetics were the main drivers for their favored design of DEEPs. The acceptability of digital healthcare in connection to DEEPs was found to be related to the participants' level of digital literacy.

    Conclusions

    The participants generally had a positive attitude towards DEEPs and the digital aspects of them. However, to accept digital healthcare in connection to DEEPs, it should be adaptable and easy to use for everyone. The combination of digital healthcare and on-demand fabricated DEEPs could potentially contribute to higher patient adherence and safety in the future.

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  • 28.
    Chao, Meie
    et al.
    Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark..
    Öblom, Heidi
    Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark.;Abo Akad Univ, Fac Sci & Engn, Pharmaceut Sci Lab, Artillerigatan 6A, Turku 20520, Finland..
    Cornett, Claus
    Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark..
    Bøtker, Johan
    Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark..
    Rantanen, Jukka
    Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark..
    Kälvemark Sporrong, Sofia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark.
    Genina, Natalja
    Univ Copenhagen, Dept Pharm, Univ Pk 2, DK-2100 Copenhagen, Denmark..
    Data-Enriched Edible Pharmaceuticals (DEEP) with Bespoke Design, Dose and Drug Release2021In: Pharmaceutics, E-ISSN 1999-4923, Vol. 13, no 11, article id 1866Article in journal (Refereed)
    Abstract [en]

    Data-enriched edible pharmaceuticals (DEEP) is an approach to obtain personalized medicine, in terms of flexible and precise drug doses, while at the same time containing data, embedded in quick response (QR) codes at a single dosage unit level. The aim of this study was to fabricate DEEP with a patient-tailored dose, modify drug release and design to meet patients' preferences. It also aimed to investigate physical stability in terms of the readability of QR code patterns of DEEP during storage. Cannabinoids, namely, cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), were used as the model active pharmaceutical ingredients (APIs). Three different substrates and two colorants for the ink were tested for their suitability to fabricate DEEP by desktop inkjet printing. Flexible doses and customizable designs of DEEP were obtained by manipulating the digital design of the QR code, particularly, by exploring different pattern types, embedded images and the physical size of the QR code pattern. Modification of the release of both APIs from DEEP was achieved by applying a hydroxypropyl cellulose (HPC) polymer coating. The appearance and readability of uncoated and polymer-coated DEEP did not change on storage in cold and dry conditions; however, the HPC polymer layer was insufficient in preserving the readability of the QR code pattern in the extreme storage condition (40 °C and 75% relative humidity). To sum up, the DEEP concept provides opportunities for the personalization of medicines, considering also patients’ preferences.

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  • 29.
    Chou, Chia-Ying
    et al.
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Holländer Pettersson, Niklas
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Helander, Thomas
    Kanthal AB, Box 502, 734 27 Hallstahammar, Sweden.
    Harlin, Peter
    Sandvik Additive Manufacturing, Sandvik AB, Box 510, 101 30 Stockholm, Sweden.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Odqvist, Joakim
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Lindwall, Greta
    Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
    Precipitation kinetics during post heat treatment of an additively manufactured ferritic stainless steelManuscript (preprint) (Other academic)
  • 30.
    Daly, Colin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Increased build rate by laser powder bed fusion of SSAB steel powder2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    SSAB has built a pilot gas atomization facility looking to expand their expertise of steel into the metal powder and additive manufacturing industry. Laser powder bed fusion is an additive manufacturing method that melts and fuse metal feedstock powder together layer by layer using a high intensity laser. The complex process requires optimization in order to be competitive. The process parameters laser power, scan speed, hatch distance and layer thickness largely govern the build rate and total production time. To increase the build rate, two iterations of test cubes with unique parameters sets were experimentally printed. Evaluation of relative density, porosity, microstructure, hardness and mechanical properties was performed. All results were compared to a reference parameter set previously studied. A candidate parameter set successfully increased the build rate by 116% while maintaining satisfactory material properties.

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    Exjobb SSAB FINAL
  • 31.
    Deepankar Reddy, Attivarapu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Bhat, Hemanth Ramesh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Determining the factors influencing In-House Implementation of Additive Manufacturing versus External Supplier Reliance in the Surgical Field: Quantitative Research2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing (AM), also known as 3D printing, has arisen as a revolutionary technology with the potential to revolutionize numerous industries, including the medical industry. It is a layer-by-layer manufacturing process used to create intricate structures. Numerous industries are planning to implement it on a large scale in order to meet the bespoke market demands as a result of its ability to produce individualized components. This study investigates the determinants influencing the adoption of AM in-house versus reliance on external suppliers for applications involving additive manufacturing.

    The study acknowledges the significant impact that AM has had on the evolution of the medical field, allowing for customized medical devices, patient-specific implants, and sophisticated surgical instruments. The purpose of this study is to determine the factors influencing the adoption of AM in-house versus reliance on external suppliers for applications involving additive manufacturing. This study utilized a quantitative approach with a survey-based methodology. The sample population consisted of university hospital surgeons from various origins. This research aims to gain insight into their preferences, motivations, and concerns when it comes to implementing AM by analysing their perspectives. The study employs the Consolidated Framework for Implementation Research (CFIR) framework to analyse the findings. This theoretical framework offers a comprehensive lens through which to analyse the factors that influence the adoption of AM in the medical setting. Utilizing the CFIR framework, this study investigates the numerous factors that influence the perceptions and decision-making processes of surgeons.

    In conclusion, this research examines the determinants influencing the adoption of AM in-house versus reliance on external suppliers for applications involving additive manufacturing. The quantitative approach, coupled with the application of the CFIR framework, enables a thorough examination of the factors that influence the decision-making processes of surgeons. This study's findings have implications for the future implementation and utilization of AM in the medical field, thereby contributing to the advancement of patient care and surgical procedures.

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    Additive Manufacturing implementation in medical care
  • 32.
    Deole, Dhruva
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    3D Printing of Magnesium- and Manganese-Based Metal-Organic Frameworks for Gas Separation Applications2022Student paper other, 10 HE creditsStudent thesis
    Abstract [en]

    Metal Organic Frameworks (MOFs) are a class of porous materials that are predominantly obtained as powders and have been investigated as a solid sorbent for gas separation or carbon capture applications from combustion exhaust gases. The manufacturing of products with MOFs to use them for real life applications is still a major problem. The most common productization method used is to form pellets of the powder MOFs. This has a limitation on the product shape which makes it difficult for it to be used in gas separation applications. This study focuses on using additive manufacturing technique to give MOFs a lattice (mesh-like) geometry which is useful for gas separation applications as the mixture of gases would be able to pass through the lattice structure and be separated due to the inherent MOF properties and characteristics. Two MOFs based on magnesium and manganese salts have been studied in this project. An extrudable paste developed using alginate gel as a binder with these MOFs. With alterations in paste formulations and 3D printer parameters, lattice structures were printed using the two MOFs. CO2 and N2 gas uptakes were measured showing that the structure adsorbs CO2 gas to a higher extend which results in the separation of N2 gas in both materials. When compared to their pristine powder form, other properties of the MOFs such as crystallinity, microstructure, reusability and surface area remain to be preserved after being 3D printed in both cases. 

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  • 33. Deshmukh, Kaustubh
    Exploratory study on Additive Manufacturing in Urban mobility2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis report presents a comprehensive study on the design and development of an Additively manufactured Unit cell for car door panels, aiming to enhance impact resistance and reduce noise transmission to the vehicle cabin. In order to accomplish these goals, the study focuses on combining two novel techniques namely quasi-zero stiffness (QZS) structures and phononic crystals (both scattering and locally resonating type).The research begins by looking into similar research work, choosing appropriate unit cell topologies, and characterizing the materials suitable for AM. The performance of the unit cell design is then assessed using FEA simulations. To improve noise absorption and impact resistance, optimization techniques can be used.The experimental results demonstrate that the combination of QZS structures effectively enhances the unit cell’s ability to withstand impacts by redistributing and dissipating energy. Additionally, phononic crystal integration that employs both scattering and locally resonating mechanisms proves successful in attenuating noise transmission across a wide frequency range.The projected performance advantages of the 3D printed unit cell prototypes are confirmed by experimental testing. Measurements of noise absorption, impact resistance and mechanical testing confirm the viability of the suggested design.The findings of this research contribute to the advancement of additive manufacturing techniques in the automotive industry. The proposed unit cell design for 3D printing exhibits potential for enhancing occupant safety and acoustic comfort in automotive door panels. The proposed technologies have the potential to be further optimized and integrated to produce enhanced automotive door panels with higher impact resistance and noise reduction capabilities

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  • 34.
    Diez-Escudero, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Andersson, Brittmarie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Carlsson, Elin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Recker, Benjamin
    Waldemar Link GmbH Co KG, D-22339 Hamburg, Germany..
    Link, Helmut
    Waldemar Link GmbH Co KG, D-22339 Hamburg, Germany..
    Järhult, Josef D.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Hailer, Nils
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    3D-printed porous Ti6Al4V alloys with silver coating combine osteocompatibility and antimicrobial properties2022In: Biomaterials Advances, ISSN 2772-9516, E-ISSN 2772-9508, Vol. 133, article id 112629Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing allows for the production of porous metallic implants for use in orthopaedics, providing excellent mechanical stability and osseointegration. However, the increased surface area of such porous implants also renders them susceptible to bacterial colonization. In this work, two trabecular porous Ti6Al4V alloys produced by electron beam melting were investigated for their osteocompatibility and antimicrobial effects, comparing samples with a silver-coated surface to uncoated samples. Dense grit-blasted Ti samples were used for comparison. The porous samples had pore sizes of 500-600 mu m and 5 to 10 mu m surface roughness, the silver-coated samples contained 7 at.% Ag, resulting in a cumulative Ag release of 3.5 ppm up to 28 days. Silver reduced the adhesion of Staphylococcus aureus to porous samples and inhibited 72 h biofilm formation by Staphylococcus epidermidis but not that of S. aureus. Primary human osteoblast adhesion, proliferation and differentiation were not impaired in the presence of silver, and expression of osteogenic genes as well as production of mineralized matrix were similar on silver-coated and uncoated samples. Our findings indicate that silver coating of porous titanium implants can achieve antimicrobial effects without compromising osteocompatibility, but higher silver contents may be needed to yield a sustained protection against fast-growing bacteria.

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  • 35.
    Diez-Escudero, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Andersson, Brittmarie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Hailer, Nils
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Hexagonal pore geometry and the presence of hydroxyapatite enhance deposition of mineralized bone matrix on additively manufactured polylactic acid scaffolds2021In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 125, article id 112091Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) has revolutionized the design of regenerative scaffolds for orthopaedic applications, enabling customizable geometric designs and material compositions that mimic bone. However, the available evidence is contradictory with respect to which geometric designs and material compositions are optimal. There is a lack of studies that systematically compare different pore sizes and geometries in conjunction with the presence or absence of calcium phosphates. We therefore evaluated the physicochemical and biological properties of additively manufactured scaffolds based on polylactic acid (PLA) in combination with hydroxyapatite (HA). HA was either incorporated in the polymeric matrix or introduced as a coating, yielding 15 and 2% wt., respectively. Pore sizes of the scaffolds varied between 200 and 450 um and were shaped either triangularly or hexagonally. All scaffolds supported the adhesion, proliferation and differentiation of both primary mouse osteoblasts and osteosarcoma cells up to four weeks, with only small differences in the production of alkaline phosphatase (ALP) between cells grown on different pore geometries and material compositions. However, mineralization of the PLA scaffolds was substantially enhanced in the presence of HA, either embedded in the PLA matrix or as a coating at the surface level, and by larger hexagonal pores. In conclusion, customized HA/PLA composite porous scaffolds intended for the repair of critical size bone defects were obtained by a cost-effective AM method. Our findings indicate that the analysis of osteoblast adhesion and differentiation on experimental scaffolds alone is inconclusive without the assessment of mineralization, and the effects of geometry and composition on bone matrix deposition must be carefully considered in order to understand the regenerative potential of experimental scaffolds.

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  • 36.
    Diez-Escudero, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Carlsson, Elin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Andersson, Brittmarie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Järhult, Josef D.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Hailer, Nils
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Trabecular Titanium for Orthopedic Applications: Balancing Antimicrobial with Osteoconductive Properties by Varying Silver Contents2022In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 14, no 37, p. 41751-41763Article in journal (Refereed)
    Abstract [en]

    Periprosthetic joint infection (PJI) and implant loosening are the most common complications after joint replacement surgery. Due to their increased surface area, additively manufactured porous metallic implants provide optimal osseointegration but they are also highly susceptible to bacterial colonization. Antibacterial surface coatings of porous metals that do not inhibit osseointegration are therefore highly desirable. The potential of silver coatings on arthroplasty implants to inhibit PJI has been demonstrated, but the optimal silver content and release kinetics have not yet been defined. A tight control over the silver deposition coatings can help overcome bacterial infections while reducing cytotoxicity to human cells. In this regard, porous titanium sputtered with silver and titanium nitride with increasing silver contents enabled controlling the antibacterial effect against common PJI pathogens while maintaining the metabolic activity of human primary cells. Electron beam melting additively manufactured titanium alloys, coated with increasing silver contents, were physico-chemically characterized and investigated for effects against common PJI pathogens. Silver contents from 7 at % to 18 at % of silver were effective in reducing bacterial growth and biofilm formation. Staphylococcus epidermidis was more susceptible to silver ions than Staphylococcus aureus. Importantly, all silver-coated titanium scaffolds supported primary human osteoblasts proliferation, differentiation, and mineralization up to 28 days. A slight reduction of cell metabolic activity was observed at earlier time points, but no detrimental effects were found at the end of the culture period. Silver release from the silver-coated scaffolds also had no measurable effects on primary osteoblast gene expression since similar expression of genes related to osteogenesis was observed regardless the presence of silver. The investigated silver-coated porous titanium scaffolds may thus enhance osseointegration while reducing the risk of biofilm formation by the most common clinically encountered pathogens.

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  • 37.
    Diez-Escudero, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics. Uppsala Univ, Dept Mat Sci & Engn, Div Appl Mat Sci, Dag Hammarskjolds Vag 20, S-75237 Uppsala, Sweden..
    Harlin, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Isaksson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Porous polylactic acid scaffolds for bone regeneration: A study of additively manufactured triply periodic minimal surfaces and their osteogenic potential2020In: Journal of Tissue Engineering, ISSN 2041-7314, Vol. 11, article id 2041731420956541Article in journal (Refereed)
    Abstract [en]

    Three different triply periodic minimal surfaces (TPMS) with three levels of porosity within those of cancellous bone were investigated as potential bone scaffolds. TPMS have emerged as potential designs to resemble the complex mechanical and mass transport properties of bone. Diamond, Schwarz, and Gyroid structures were 3D printed in polylactic acid, a resorbable medical grade material. The 3D printed structures were investigated for printing feasibility, and assessed by morphometric studies. Mechanical properties and permeability investigations resulted in similar values to cancellous bone. The morphometric analyses showed three different patterns of pore distribution: mono-, bi-, and multimodal pores. Subsequently, biological activity investigated with pre-osteoblastic cell lines showed no signs of cytotoxicity, and the scaffolds supported cell proliferation up to 3 weeks. Cell differentiation investigated by alkaline phosphatase showed an improvement for higher porosities and multimodal pore distributions, suggesting a higher dependency on pore distribution and size than the level of interconnectivity.

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    FULLTEXT01
  • 38.
    Dsouza, Erol Christopher
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Hardi, Yash Rajesh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering.
    Factors Affecting the Implementation of Additive Manufacturing Technology in Healthcare.2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing (AM) has made it possible for patients to have personalized healthcare treatment such as implants, surgical guides etc., which was not possible previously. Despite the massive opportunity of custom-made implants, some factors made their use in clinical practice more difficult. Keeping this in focus the purpose of our thesis is i) To identify stakeholders relevant to AM in healthcare ii) Identify barriers for AM in healthcare iii) Propose a business framework based on barriers and stakeholder identification. 

    A literature review delineated current barriers for AM in general as well as specific to healthcare. Additionally, different dimensions that AM impacts in healthcare and the current business frameworks used were explored. A case study design was applied using deductive reasoning. The Data was collected from semi-structured interviews with the help of snowball purposive sampling. Also, a part of the studies relied on archival data. CFIR framework was employed for data collection, and an interview guide was prepared using the same. The stakeholder analysis model and new business concepts were also utilized under the theoretical framework. Data from the interview was analysed by thematic analysis. The main themes were the Inner setting, Intervention characteristics, Network, Individual professional characteristics, and Outer setting.

     

    The study results are categorized based on the technology used for printing, i.e., Metal printing and Polymer printing. Metal printing superseded polymer printing in terms of the number of barriers. Moreover, in terms of the ‘Inner setting,’ common barriers for both printing technologies were lack of training for medical professionals w.r.t AM machines and lack of skilled personal for handling the design software. In terms of ‘Intervention characteristics’, lack of infrastructure (not good enough scanner for scanning patients) and lack of user-friendly software were few common barriers for both printing technologies. The theme ‘Individual professional characteristics’ contained barriers like lack of entrepreneurial mindset (lacking in individuals who take initiatives and invest time), laggard’s attitude (individuals not willing to change the way they work), technological barrier due to generation gap, and lack of practical experience. Lack of demand and lack of legal framework were barriers for metal printing in the context of the ‘Outer setting’.

     Lastly, with evidence of AM facing numerous barriers, it becomes paramount to examine those barriers at different levels critically during its implementation. Addressing and tackling them with a solution regarding business frameworks and knowledge of relevant stakeholders can alleviate some of the hurdles.   

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  • 39. EBI, NIKHIL JOSEPH
    Methodology for evaluation of long-term mechanical properties of viscoelastic materials2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing (AM) enables the fabrication of complex geometries using layer-by-layerdeposition of materials like polymers and metals. However, predicting the long-term viscoelasticcharacteristics of AM polymer parts is challenging due to limited available data. This thesisinvestigates the applicability of time-temperature superposition (TTS) to forecast mechanicalbehaviour over extended timescales beyond experimentally feasible testing durations.Comprehensive stress relaxation testing was systematically conducted on 3D-printed polylacticacid (PLA) samples across a temperature range of 26°C to 34°C using a customised climatechamber. The results demonstrated an increasing rate and extent of stress relaxation at highertemperatures, confirming the viscoelasticity of the printed PLA. Leveraging Python programmingand the Williams-Landel-Ferry (WLF) equation, the individual stress relaxation curves at differenttemperatures were shifted to create master curves. By quantitatively determining the shift factors,a continuous prediction of viscoelastic properties spanning much longer time durations wasachieved. Experimental validation through prolonged relaxation testing showed reasonableagreement between the actual mechanical data and the model predictions, thereby validating thecapability of TTS in expanding the behavioural forecast. This research provides a robustframework and methodology for the accelerated determination of time-dependent viscoelasticcharacteristics of polymers fabricated through additive manufacturing. The computational toolsand experimental techniques established here can be extended to other AM materials likecomposites and metal alloys. Overall, this thesis demonstrates a methodology for timetemperaturesuperposition as a viable and powerful tool for developing comprehensive predictivemodels of the long-term mechanical performance of viscoelastic material.

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  • 40.
    Ericsson, A.
    et al.
    Lund Univ, Div Solid Mech, POB 118, SE-75120 Lund, Sweden..
    Pacheco, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindwall, J.
    Luleå Tech Univ, Mech Solid Mat, SE-97187 Luleå, Sweden..
    Hallberg, H.
    Lund Univ, Div Solid Mech, POB 118, SE-75120 Lund, Sweden..
    Fisk, M.
    Lund Univ, Div Solid Mech, POB 118, SE-75120 Lund, Sweden.;Malmö Univ, Mat Sci & Appl Math, SE-20506 Malmö, Sweden..
    Transient nucleation in selective laser melting of Zr-based bulk metallic glass2020In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 195, article id 108958Article in journal (Refereed)
    Abstract [en]

    The crystallization rate during selective laser melting (SLM) of bulk metallic glasses (BMG) is a critical factor in maintaining the material's amorphous structure. To increase the understanding of the interplay between the SLM process and the crystallization behavior of BMGs, a numerical model based on the classical nucleation theory has been developed that accounts for the rapid temperature changes associated with SLM. The model is applied to SLM of a Zr-based BMG and it is shown that the transient effects, accounted for by the model, reduce the nucleation rate by up to 15 orders of magnitude below the steady-state nucleation rate on cooling, resulting in less nuclei during the build process. The capability of the proposed modelling approach is demonstrated by comparing the resulting crystalline volume fraction to experimental findings. The agreement between model predictions and the experimental results clearly suggests that transient nucleation effects must be accounted for when considering the crystallization rate during SLM processing of BMGs.

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  • 41.
    Ericsson, Anders
    et al.
    Lund University.
    Pacheco, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Marattukalam, Jithin J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Dalgliesh, Robert M.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Fisk, Martin
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Crystallization of a Zr-based metallic glass produced by laser powder bed fusion and suction casting2021In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 571, article id 120891Article in journal (Refereed)
    Abstract [en]

    The crystallization behavior during low-temperature annealing of samples of the Zr59.3Cu28.8Al10.4Nb1.5 (at%) bulk metallic glass produced by suction casting and the laser powder bed fusion (LPBF) process was studied with small-angle neutron scattering (SANS), X-ray diffraction, and scanning electron microscopy. The in-situ SANS measurements during isothermal annealing reveal that the phase separation in the LPBF processed material proceeds at a smaller characteristic length-scale than the cast material. Quantitative analysis of the SANS data shows that, while the crystallization process in both materials proceeds through rapid nucleation followed by diffusion-limited growth, the LPBF processed material crystallizes with a smaller cluster size and at a higher rate. The smaller cluster size is attributed to the elevated oxygen content in the LPBF processed material which reduces the nucleation barrier and thus the thermal stability.

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  • 42.
    Eriksson, Philip
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Evaluation of mechanical and microstructural properties for laser powder-bed fusion 316L2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work was done to get a fundamental knowledge of the mechanical and microstructural properties of 316L stainless steel fabricated with the additive manufacturing technique, laser powder-bed fusion (L-PBF). The aims of the thesis were to study the mechanical and microstructural properties in two different building orientations for samples built in two different machines, and to summarize mechanical data from previous research on additive manufactured 316L.

    Additive manufacturing (AM) or 3D-printing, is a manufacturing technique that in recent years has been adopted by the industry due to the complexity of parts that can be built and the wide range of materials that can be used. This have made it important to understand the behaviour and properties of the material, since the material differs from conventionally produced material. This also adds to 316L, which is an austenitic stainless steel used in corrosive environments.

    To study the effect of the building orientation, samples of 316L were built in different orientations on the build plate. The density and amount of pores were also measured. Tensile testing and Charpy-V testing were made at room temperature. Vickers hardness was also measured. Microstructure and fracture surfaces were examined using light optical microscope (LOM) and scanning electron microscope (SEM).

    The microstructure of the 316L made with L-PBF was found to have meltpools with coarser grains inside them, sometime spanning over several meltpools. Inside these coarser grains was a finer cellular/columnar sub-grain structure. The tensile properties were found to be anisotropic with higher strength values in the orientation perpendicular to the building direction. Also high dense samples had higher tensile properties than low dense samples. The impact toughness was found to be influenced negatively by high porosity. Hardness was similar in different orientations, but lower for less dense samples. Defects due to lack of fusing of particles were found on both the microstructure sample surfaces and fracture surfaces. The values from this study compare well with previous reported research findings.

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  • 43.
    Erol, Burak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Datar, Maitreya Chandrashekhar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Adoption of Additive Manufacturing in the Food Industry: Exploring marketing, sales, and after-sales strategies for the adoption of Additive Manufacturing in the food industry.2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive Manufacturing (AM) is a technology that enables to print three dimensional solid objects which can be metal, plastic, and similar. AM has a lot of advantages such as lead time reduction and reduction in the number of steps required for manufacturing compared to the traditional manufacturing (TM) method. 

     

    This research is focused on adoption of AM in the food manufacturing industry. The use of AM in the food industry currently seems to be low. Therefore, the main aim of the research is to understand adoption of AM through marketing, sales, and after-sales strategies, which can be best suited for introduction and saturation of AM products and applications in the food industry. 

    The primary data is gathered from the potential customers (experts from the food industry), sales personnel who sell products and machinery in the food industry and the employees of the sponsor company, and it consists of thirteen different interviews. Qualitative interviews were conducted to obtain an in-depth knowledge about the perceptions and perspectives of AM in the food industry.

    AM has the potential to be adopted as the main manufacturing method for spare parts in the food industry. But, considering the market today, the potential of adoption seems to be wasted. Three different analyses help in determining the current situation of the AM industry and help to understand the potential that AM brings to the food industry.

    Outcomes of the qualitative interviews present the researchers with in-depth knowledge of facilitators and barriers that AM companies may face when approaching customers from the food industry. Outcomes of the qualitative interviews also suggest that there is limited knowledge about AM in the food industry. There is also a knowledge gap about the regulations and possibilities to use AM in the food industry based on these regulations.

    Indeed, food manufacturers are interested in the adoption of newer technologies and present the researchers with the formation of various themes to develop strategies for adoption of AM, through a recommendable marketing, sales and aftersales strategy that can be employed by AM companies.

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    Adoption of Additive Manufacturing in the Food Industry
  • 44.
    Fakoya, Moyosore Babatomide
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Uppsala University.
    Effect of Heat Treatment on the Microstructure and Hardness Property of Additively Manufactured Ti6Al-4V and Ti-6Al-4V-4.5wt.%316L Componentsfor Biomedical Applications.2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractThe continuous advancement of medical implants technology presents exciting possibilities.Laser Powder Bed Fusion (L-PBF) additive manufactured Ti-6Al-4V alloy implants showtremendous promise as they offer the potential for highly personalized implants, improved implantfunctionality and enhanced long-term outcomes. However, the microstructure and microhardnessproperty of components produced through L-PBF are inferior when compared to theircounterparts manufactured using traditional methods. Recent investigation presents aninnovative method that has potential to address these microstructure and microhardnesschallenges. This method creates a spatially modulated Ti alloy by adding 316L powder into Ti-6Al-4V powder before printing with L-PBF. The resulting alloy shows a reduced formation ofcoarse β columnar grains into more preferred equiaxed grains. However, the effect of heattreatment operation on this spatially modulated alloy has not yet been explored.Thus, this present study reports on the effect of heat treatment operation on the microstructureand hardness property of Laser Powder Bed Fusion (L-PBF)- fabricated Ti-6Al-4V and Ti-6Al-4V-4.5wt.%316L alloys respectively. The heat treatment processes include both super- and sub- betatransus temperature (Tβ). After the heat treatment processes, the samples were either water-quenched or air-cooled. X-ray Diffraction (XRD), Light Optical Microscopy (LOM), and ScanningElectron Microscopy (SEM) were the characterization techniques performed on these alloys andthese qualitative data gathered were correlated with their microhardness measurements. The as-fabricated Ti-6Al-4V alloy exhibited a martensite α՛ microstructure. On the other hand, the Ti-6Al-4V-4.5wt.%316L alloy possessed a β grain structure. Ti-6Al-4V alloy, subjecting it to the 1020˚Csuper-transus treatment followed by water quenching resulted in the formation of new α՛martensite microstructure and fine primary alpha. When the Ti-6Al-4V specimen was subjectedto 1020˚C and then air cooled, a bimodal microstructure comprising coarse primary alpha andα+β lamellar was formed. The 920˚C sub-transus heat treatment also produced α+β lamellarstructure. For the 1020˚C water-quenched Ti-6Al-4V sample, the microhardness value increasedby 7.3% and 11% in the transverse and cross-sections to the build direction axis, respectivelywhen compared to the as-built parts. Conversely, Ti-6Al-4V-4.5wt.%316L alloy exhibited evenlydistributed primary alpha plates in beta matrix for both the water-quenched and air-cooledsamples at 1020˚C and 920˚C. On the other hand, heat treatment at 800 ˚C retains the as-builtbeta grain morphology while alpha plates precipitate along the grain boundaries. Themicrohardness results suggest that performing only transus heat treatment on the Ti-6Al-4V-4.5wt.%316L alloy was insufficient to significantly alter its hardness properties.Key words: Additive manufacturing, Ti-6Al-4V, Laser powder bed fusion, microstructure control.

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  • 45.
    Feldt, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Hedberg, Petra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Jarlöv, Asker
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Persson, Elsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Svensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Vennberg, Filippa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    You, Therese
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Independent Project in Chemical Engineering and Materials Engineering: A literature study of powder-based additive manufacturing2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The focus of this literary study was additive manufacturing (AM) and the purpose was to find general trends for selected materials that have been additively manufactured and compare them to results from other reviews. The raw materials studied were stainless steels 316L, 17-4 PH, 15-5 PH and 420, as well as tool steel H13 and nickel alloys 625, 718 and Hastelloy X. The AM techniques studied were selective laser melting (SLM), electron beam melting (EBM) and binder jetting (BJG). 

    A total of 69 articles have been studied to fulfill the purpose above. The articles were used to write a summary of the techniques, compare them to each other and to conventional methods. They were also used to create a database to compile information on mechanical properties, microstructure and process parameters. Based on the database mechanical properties for SLM tend to be higher compared to EBM. This however varied somewhat depending on the processed material. Furthermore the yield and tensile strength obtained from the database for SLM seemed to be higher compared to the values in review articles for almost all materials. Unfortunately not enough values were found for BJG to compare it to SLM and EBM.AM seems to produce weaker, equal and superior products compared to conventional methods. However due to the limited nature of the project and the research found no conclusions can be drawn about any trends, how to achieve the different results or how parameters affect the finished product. To be able to say anything with more certainty more research has to be done. Not only in general concerning the AM techniques, but more studying of existing articles is needed. Finally a standardization on how to reference properties and process parameters is necessary. Currently it is very difficult to compare results or draw conclusions due to different designations, units and a lot of missing essential information.

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  • 46.
    Feldt, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Hedberg, Petra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Jarlöv, Asker
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Persson, Elsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Svensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Vennberg, Filippa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    You, Therese
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Independent Project in Chemical Engineering and Materials Engineering: A literature study of powder-based additive manufacturing2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The focus of this literary study was additive manufacturing (AM) and the purpose was to find general trends for selected materials that have been additively manufactured and compare them to results from other reviews. The raw materials studied were stainless steels 316L, 17-4 PH, 15-5 PH and 420, as well as tool steel H13 and nickel alloys 625, 718 and Hastelloy X.The AM techniques studied were selective laser melting (SLM), electron beam melting (EBM) and binder jetting (BJG). 

    A total of 69 articles have been studied to fulfill the purpose above. The articles were used to write a summary of the techniques, compare them to each other and to conventional methods. They were also used to create a database to compile information on mechanical properties, microstructure and process parameters. Based on the database mechanical properties for SLM tend to be higher compared to EBM. This however varied somewhat depending on the processed material. Furthermore the yield and tensile strength obtained from the database for SLM seemed to be higher compared to the values in review articles for almost all materials. Unfortunately not enough values were found for BJG to compare it to SLM and EBM.AM seems to produce weaker, equal and superior products compared to conventional methods. However due to the limited nature of the project and the research found no conclusions can be drawn about any trends, how to achieve the different results or how parameters affect the finished product. To be able to say anything with more certainty more research has to be done. Not only in general concerning the AM techniques, but more studying of existing articles is needed. Finally a standardization on how to reference properties and process parameters is necessary. Currently it is very difficult to compare results or draw conclusions due to different designations, units and a lot of missing essential information.

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    fulltext
  • 47.
    Fors, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Hellgren, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Henriksson, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sirén, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sundström, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Wemlén, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Microcrack Analysis in VBN Components AM Steel Alloy: A microcrack characterisation and origin determination study2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Electron beam additive manufacturing (EBAM) offers a high degree of control over highly complex structures. An EBAM alloy in development by the company VBN Components, specialising in wear-resistant AM steel, has been found to develop microcracks which has been partially characterised in this paper.

    EDS analysis of microcracks in the bulk of the alloy samples has indicated that two carbides congregate in and around the cracks. Thermodynamic simulation of the system in the software Thermo-Calc indicated that the carbides are likely to be MC with V and M6C with Fe, Mo, and W. EBSD analysis was performed, but only a small amount of data was achieved due to difficulties with the sample preparation. From the small amount of data it was still observed that there might be a relation between cracking and large misorientation angles between grains, this however needs more research. Since sufficient sample preparation for EBSD analysis finally was achieved, it is strongly suggested that more samples are prepared according to guidelines presented in this work, so that the correlation between cracking and misorientation angle can be further investigated. Hardness measurements through nanoindentation around cracks proved inconclusive in determining statistically significant differences to hardness in crack-free areas. The overall result of the characterisation indicates both grain orientation and precipitated carbides to be linked with microcracks in the alloy; which should be studied further.

  • 48.
    Fuchs, Florian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Parameter Optimization in the Additive Manufacturing Process of High-Performance Polymers2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a simulation based multi print parameter optimization for the FFF printing process of a PEEK filament has been performed. The simulation is based on an in-house developed thermal heat transfer analysis using the Matlab and Abaqus software. The optimization was focused on maximizing the interlayer bonding (tensile) strength and the degree of crystallinity to improve the part performance. In addition, the impact of this optimization on the dimensional accuracy was evaluated. A simulation-based approach was chosen to predict part performance while reducing extensive testing and costly material waste. A full factorial design of experiments was used to evaluate the effects and interactions of several printing parameters, including nozzle temperature, chamber temperature, print speed, and fan setting. Based on the simulation predictions, two linear regression models were derived for the achievable tensile strength and degree of crystallinity. The regression models were used for multiparameter optimization using the MINITAB software. Finally, an optical and mechanical comparison of samples printed with optimized and initial parameters was performed. The optimization resulted in a geometric degradation of the dimensional accuracy of the printed specimens, an increase in the degree of crystallinity, and a significant increase in the average tensile strength of 206%. 

    The full text will be freely available from 2028-07-21 14:32
  • 49.
    Ghandour, Salim
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Novel Materials and Implant Designs for the Treatment of Degenerative Disc Disease2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The overarching objective of this thesis was to develop intervertebral implants for degenerated discs through design, fabrication, and mechanical validation. The research had four primary aims, each addressing different facets of implant development.

    The first aim was to design a structurally optimized fusion intervertebral cage capable of accommodating weak bioactive materials. Topology optimization was employed to design cages using titanium and calcium phosphate. The cage’s integrity was verified using finite element simulations, fabricated using additive manufacturing, and validated using ASTM F2077. Imaging techniques were utilized to assess the quality of the produced cages. These evaluations confirmed the mechanical reliability of the produced cage, able to incorporate around 75% in volume of a bioactive calcium phosphate material, protected by the titanium.

    The second aim was to develop a clinically relevant degeneration model for the biomechanical evaluation of percutaneous cement discoplasty (PCD). To this end, voids were generated in ovine functional spinal units (FSUs) using papain. The results were compared with clinical data where parameters such as void volume percentage, disc height, and morphology of the induced injury were assessed. FSUs were treated with PCD using bone cement, and mechanically evaluated under healthy, injured, and treated conditions to determine if PCD could stabilize the spinal segment. The void induced showed similar parameters compared to the clinical data. Further, the stability of the spine was significantly reduced after degeneration and restored after treatment, highlighting the effectiveness of the degeneration method and PCD treatment.

    The third aim was to evaluate the suitability of novel bone cements for their use in PCD. This study examined the tensile and fatigue properties of a low-modulus cement (VSLA) primarily intended for vertebroplasty. The formulation was tested in tensile and fatigue. VSLA showed a significant decrease in tensile and fatigue properties when compared to commercial cements. This study set a baseline for future low-modulus cements that may be tested for use in PCD.

    The fourth aim was to evaluate an alternative cement due to the low viscosity of VSLA, which may not be suitable for discoplasty. This study assessed the fatigue and long-term properties of a high-viscosity low-modulus cement (hv-LA-PMMA). The hv-LA-PMMA showed a significant reduction of mechanical and fatigue properties when compared to its commercial base. Notably, the fatigue properties were similar to those of the annulus fibrosus in the disc. Additionally, its high viscosity renders it a promising alternative to the bone cements currently utilized in PCD.

    In conclusion, this thesis successfully addressed the design, fabrication, and mechanical validation of two types of intervertebral implants for degenerated discs. The research outcomes contribute with valuable insights into the design of fusion cages, a degeneration model to evaluate PCD, and the assessment of low-modulus cements for use in PCD.

    List of papers
    1. A Topology Optimized Spinal Fusion Cage for the Use of Weak but Osteoinductive Bioceramics as Synthetic Bone Grafts
    Open this publication in new window or tab >>A Topology Optimized Spinal Fusion Cage for the Use of Weak but Osteoinductive Bioceramics as Synthetic Bone Grafts
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biomaterials Science
    Research subject
    Engineering Science with specialization in Biomedical Engineering
    Identifiers
    urn:nbn:se:uu:diva-516529 (URN)
    Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2023-11-24
    2. An ex-vivo model for the biomechanical assessment of cement discoplasty
    Open this publication in new window or tab >>An ex-vivo model for the biomechanical assessment of cement discoplasty
    Show others...
    2022 (English)In: Frontiers in Bioengineering and Biotechnology, E-ISSN 2296-4185, Vol. 10, article id 939717Article in journal (Refereed) Published
    Abstract [en]

    Percutaneous Cement Discoplasty (PCD) is a surgical technique developed to relieve pain in patients with advanced degenerative disc disease characterized by a vacuum phenomenon. It has been hypothesized that injecting bone cement into the disc improves the overall stability of the spinal segment. However, there is limited knowledge on the biomechanics of the spine postoperatively and a lack of models to assess the effect of PCD ex-vivo. This study aimed to develop a biomechanical model to study PCD in a repeatable and clinically relevant manner. Eleven ovine functional spinal units were dissected and tested under compression in three conditions: healthy, injured and treated. Injury was induced by a papain buffer and the treatment was conducted using PMMA cement. Each sample was scanned with micro-computed tomography (CT) and segmented for the three conditions. Similar cement volumes (in %) were injected in the ovine samples compared to volumes measured on clinical PCD CT images. Anterior and posterior disc heights decreased on average by 22.5% and 23.9% after injury. After treatment, the anterior and posterior disc height was restored on average to 98.5% and 83.6%, respectively, of their original healthy height. Compression testing showed a similar stiffness behavior between samples in the same group. A decrease of 51.5% in segment stiffness was found after injury, as expected. The following PCD treatment was found to result in a restoration of stiffness—showing only a difference of 5% in comparison to the uninjured state. The developed ex-vivo model gave an adequate representation of the clinical vacuum phenomena in terms of volume, and a repeatable mechanical response between samples. Discoplasty treatment was found to give a restoration in stiffness after injury. The data presented confirm the effectiveness of the PCD procedure in terms of restoration of axial stiffness in the spinal segment. The model can be used in the future to test more complex loading scenarios, novel materials, and different surgical techniques.

    Place, publisher, year, edition, pages
    Frontiers Media S.A., 2022
    Keywords
    spine, mechanical properties, discoplasty, bone cement, disc degeneration, papain, ex-vivo
    National Category
    Biomaterials Science Applied Mechanics Orthopaedics
    Research subject
    Engineering Science with specialization in Biomedical Engineering
    Identifiers
    urn:nbn:se:uu:diva-491829 (URN)10.3389/fbioe.2022.939717 (DOI)000932957100001 ()36118564 (PubMedID)
    Funder
    EU, Horizon 2020, 812765
    Note

    This research has received funding from EIT Health(SOFTBONE, project nr 20519), supported by EIT, a body of the European Union, and from the European Union’s Horizon2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 812765.

    Available from: 2022-12-24 Created: 2022-12-24 Last updated: 2023-11-24Bibliographically approved
    3. Quasi-static and dynamic mechanical properties of a low-modulus bone cement for spinal applications
    Open this publication in new window or tab >>Quasi-static and dynamic mechanical properties of a low-modulus bone cement for spinal applications
    2023 (English)In: Open Research Europe, E-ISSN 2732-5121, Vol. 3, article id 203Article in journal (Refereed) Published
    Abstract [en]

    Background:

    Polymethylmethacrylate (PMMA) bone cement is extensively used in spinal procedures such as vertebroplasty and kyphoplasty, while its use in percutaneous cement discoplasty (PCD) is not yet widely spread. A main issue for both application sites, vertebra and disc, is the mismatch in stiffness between cement and bone, potentially resulting in adjacent vertebral fractures and adjacent segment disease. Tailoring the cement modulus using additives is hence an interesting strategy. However, there is a lack of data on the tensile and tension-compression fatigue properties of these cements, relevant to the newly researched indication of PCD. 

    Method:

    A commercial PMMA cement (VS) was modified with 12%vol of linoleic acid (VSLA) and tested for quasi-static tensile properties. Additionally, tension-compression fatigue testing with amplitudes ranging from +/-5MPa to +/-7MPa and +/-9MPa was performed, and a Weibull three-parameter curve fit was used to calculate the fatigue parameters. 

    Results:

    Quasi-static testing revealed a significant reduction in VSLA’s Young’s Modulus (E=581.1±126.4MPa) compared to the original cement (E=1478.1±202.9MPa). Similarly, the ultimate tensile stress decreased from 36.6±1.5MPa to 11.6±0.8MPa. Thus, VSLA offers improved compatibility with trabecular bone properties. Fatigue testing of VSLA revealed that as the stress amplitude increased the Weibull mean number decreased from 3591 to 272 and 91 cycles, respectively. In contrast, the base VS cement reached run-out at the highest stress amplitude. However, the lowest stress amplitude used exceeds the pressures recorded in the disc in vivo, and VSLA displayed a similar fatigue life range to that of the annulus fibrosis tissue.

    Conclusions:

    While the relevance of fully reversed tension-compression fatigue testing can be debated for predicting cement performance in certain spinal applications, the results of this study can serve as a benchmark for comparison of low-modulus cements for the spine. Further investigations are necessary to assess the clinical feasibility and effectiveness of these cements.

    Place, publisher, year, edition, pages
    European Commission, 2023
    Keywords
    PMMA, bone cement, vertebroplasty, discoplasty, fatigue, tensile properties
    National Category
    Biomaterials Science
    Research subject
    Engineering Science with specialization in Biomedical Engineering
    Identifiers
    urn:nbn:se:uu:diva-516530 (URN)10.12688/openreseurope.16683.2 (DOI)
    Funder
    EU, Horizon 2020, 812765
    Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2024-06-03Bibliographically approved
    4. Mechanical Characterization and Cytocompatibility of Linoleic Acid Modified Bone Cement for Percutaneous Cement Discoplasty
    Open this publication in new window or tab >>Mechanical Characterization and Cytocompatibility of Linoleic Acid Modified Bone Cement for Percutaneous Cement Discoplasty
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biomaterials Science
    Research subject
    Engineering Science with specialization in Biomedical Engineering
    Identifiers
    urn:nbn:se:uu:diva-516531 (URN)
    Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2023-11-24
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  • 50.
    Goetz, Inga K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Pacheco, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hassila, Carl J.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Schneider, Jochen M.
    Hans, Marcus
    Convective Flow Redistribution of Oxygen by Laser Melting of a Zr-Based Amorphous Alloy2023In: Materials, E-ISSN 1996-1944, Vol. 16, no 11, article id 4113Article in journal (Refereed)
    Abstract [en]

    Oxygen impurities play a crucial role in the glass-forming ability and crystallisation behaviour of metallic glasses. In the present work, single laser tracks were produced on Zr59.3-xCu28.8 Al10.4Nb1.5Ox substrates (x = 0.3, 1.3) to study the redistribution of oxygen in the melt pool under laser melting, which provides the basis for laser powder bed fusion additive manufacturing. Since such substrates are commercially not available, they were fabricated by arc melting and splat quenching. X-ray diffraction revealed that the substrate with 0.3 at.% oxygen was X-ray amorphous, while the substrate with 1.3 at.% oxygen was partially crystalline. Hence, it is evident that the oxygen content affects the crystallisation kinetics. Subsequently, single laser tracks were produced on the surface of these substrates, and the melt pools attained from the laser processing were characterised by atom probe tomography and transmission electron microscopy. Surface oxidation and subsequent convective flow redistribution of oxygen by laser melting were identified as causes of the presence of CuOx and crystalline ZrO nanoparticles in the melt pool. Bands of ZrO likely originate from surface oxides that were moved deeper into the melt pool by convective flow. The findings presented here highlight the influence of oxygen redistribution from the surface into the melt pool during laser processing.

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