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  • 151.
    Hjälte, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Fredin, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Minimiarmering enligt Eurokod: En jämförelse mellan EKS 9 och EKS 102016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis deals with the minimum reinforcement inconcrete structures and the changes made in theregulations on this with the introduction of EKS 10. EKS10, which was introduced January 1, 2016, is theswedish national annex to the common Eurocode. Theintroduction of EKS 10 has meant that more chaptersfrom Eurocode have been adapted to swedishconditions and that the requirements for minimumreinforcement has been mitigated.As part of the thesis a calculation template has beencreated in Microsoft Excel designed to facilitate thecalculation of minimum reinforcement forByggnadstekniska byrån in Stockholm. In addition tocreating the template, common concrete sections havebeen analyzed with respect to the reinforcementquantities and the economy.The results show that the minimum amount ofreinforcement has been reduced in all of the crosssectionexamined in this thesis. The amendedprovisions have had the consequence that the minimumquantity of rienforcement in respect to reduction ofcrack width in beams and slabs have been decreased bybetween 10 and 32 percent. For walls the minimumamount of vertical reinforcement fallen by 50 percent inslender walls and by 100 percent non slender walls,while the minimum horizontal rienforcement decreasedby 75 and 100 percent respectively.According to the calculations done for a supposedexample floor, this causes a potential reduction inmaterial costs of up to 65 or 118 SEK per square meter,depending on whether or not the walls are regarded asslender.

  • 152.
    Holm, Jenny
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Precisering av vindlastens fördelning på en byggnad: Jämförelse av beräkningsmetodernas korrekthet2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The wind load represents the biggest of the horizontal loads when calculating the

    stability of a building. It is important to design the building for this load so it does not

    tip over. How the wind load is distributed on the stabilizing walls can be calculated in

    different ways. In this report some of these methods are investigated. In those

    different calculations the walls take different amount of loads depending on their

    stiffness, placement or length etc. A reference house was used to appreciate which

    calculation method gives the best result.

    In method 1 the stiffness ratio between the floor and the walls decides how the

    distribution should be made. If the floor is stiffer than the walls, case 1, the loads are

    distributed to the walls depending on their stiffness. Stiffer wall means more loads.

    But if the walls are stiffer than the floor, case 2, the load will distributed on the walls

    like a beam on fixed supports. If the walls and the floor have relatively the same

    stiffness, case 3, the load will be distributed proportionally to the section of the

    facades carried by the walls.

    Method 2 is a simplified method where only the length of the wall decides how much

    load it will take. The longer the wall the more loads it will get.

    The reference house is then put into a computer based program, FEM-Design, where

    every floor in each direction is calculated one by one. This method is considered the

    most correct method in this report, and therefore the results from the other

    methods compared by this one to check their correctness.

    The results from the reference house show that one of the ways to calculate is more

    accurate than the others when compared to the model from FEM-Design. One of the

    cases from method 1 seems to be the most correct way to calculate, but it is not the

    same case as the one using the recommended method based on the stiffness ratio.

    Furthermore, the report shows that none of these methods reflect the realistic

    distribution fairly enough. They are all missing some aspect that should be into

    consideration. In method 1, case 1, the distance between the point of application of

    the force and the wall are not considered. And for case 2 and 3, method 1, the

    properties of the walls are not taken into account in the calculation. The results show

    that both the distance to the point of application of the force and the walls properties

    have a big impact on the wind load distribution.

    Keywords: Building stability, Wind load distribution, FEM, Stiffness ratio

  • 153.
    Holm, Mathias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Engström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Logistik i byggbranschen: För förbättrad arbetsmiljö och effektivitet2013Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Logistics and supply chain management in the construction sector is an area with great potential for improvements. Today, a lot of the workers time is spent on non-value adding activities. Research has shown that waste is a large proportion of the total production cost in building projects today.

    The purpose of this report is to analyze problems concerning logistics in the construction sector. Two of Skanska’s construction projects in Uppsala have been analyzed to identify problems. The goal of the thesis is to suggest solutions regarding logistics that will improve the work environment and efficiency.

    The result shows that companies would benefit from using smart logistic services like just in time deliveries and third party logistics. Services like this should be used even if the circumstances of the project don’t require it, as they are conducive to a better working environment and heightened effectivity.

    Recommendations include having well defined routines and selecting a person responsible for receiving deliveries. Communication and cooperation with other parties in the supply chain is also important. Planning and any subsequent follow-ups have to be carried out effectively and efficiently. 

  • 154.
    Holmberg, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Linjärstyrning för aluminiumprofiler: Framtagning av prototyp2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis describes the development ofa linear guidance system suited for NORCAN's aluminium profiles. The work took place at LP Innovation, a small technical consulting company, located in Uppsala. The work started with gathering and searching for information. A lot of the information was found in product catalogs, but my supervisor was also a great source of knowledge, as well as the other engineers at the company. I also had the opportunity to work with the rea lprofiles, to get a feeling and greater understanding how they were supposed to be used. With the use of sketching and CAD, a number of concepts were generated. One of those concepts, that me and my supervisor thought, looked good were later on made into a prototype. The prototype was tested and the results were compared to one of the current solutions. An experimental design was applied to the prototype to look for improvements. When a working solution was made, some examples of applications were given, for example two different height adjustable tables.

  • 155.
    Holmquist, Jakob
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Stafström, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Dimensionering av stödmur med utgångspunkt i Lean design2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This examination paper has been commissioned by the Tunnel and Bridge unit of Ramböll in Stockholm. The purpose of the report is to describe the procedure of constructing a calculation template in Excel for the designing of a retaining wall, based on the principles of Lean design. The intention of making processes more efficient in order to save time and improve quality exists within most businesses. In management literature, one reappearing tool for making processes more efficient in the construction consulting industry is called Lean design. Lean design can be applied to all design and calculation processes for different types of bridges and structures. This report describes the background to Lean design and the process of trying to implement its principles in the making of a calculation template for the designing of a retaining wall. The purpose is to enable a more efficient designing process, where calculations are standardized, and the results of the process are comprehensibly presented to other actors within the consulting business, such as reviewers and CAD designers. The template is to be used for designing retaining walls in different situations depending on, for instance, construction and soil material, geometry and loads. Consequently, a major part of this report has been devoted to standardizing calculations for load effects and bearing capacity in the construction, depending on different possible settings. Designing is regulated by Eurocodes and national annexes, why it is important to refer to relevant chapters in the regulations. The regulations depend on settings and the field of application for the construction. Therefore, some generalizations of the design process have been made. However, during the process it has been clear that implementation of Lean design is one possible way of making construction design more efficient when it comes to time and quality.

  • 156.
    Hovemyr, Edwin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Rostvik, Ludvig
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Prioriterade studentbostäder: Ett projekteringsunderlag för kostnadseffektivare utformning utifrån studenters egna prioriteringar2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report examines what students prioritize and value in student housing. The content of the report can be used as a basis for designing new student housing to better match students' wishes, while the production of student housing can be made more cost effective. This report examines which functions of a home that students prioritize and value, and which functions students may consider sharing with others. Additionally, the report studies whether the designing of student housing needs to be differentiated to better suit different groups of students. The examination has been conducted primarily with an internet-based survey that 839 Swedish students responded to. There after an interview study was conducted with selected students representing different groups of students. The work has been carried out in cooperation with the Swedish real estate company Rikshem AB. An interview study was also conducted with other parties who are involved in and has influencing over the design of student housing. This was done in order for the proposals presented in the report to be useful to all involved, be feasible and contribute to a more cost-effective construction of student housing. As a background to the report lies the current housing shortage and the economical difficulty in getting new construction projects with student housing to be profitable. At the same time, there are dissatisfaction among many students over the student housing units that exist because of its lack of functionality and over high rents in new housing. The result of the study shows that students primarily prioritize the so-called “buddy-apartment” with two students sharing a common area, bathroom and kitchen. Secondly, students prioritize a student apartment where they alone have all the functions in the apartment. The result of the work also shows that students primarily prioritize larger social areas, having their own balconies and dishwashers in their homes. However, the former is not economically realistic to put into practice. Students do not prioritize having a washing machine in the apartment, larger workplace or additional storage. Finally, recommendations are submitted for the design of new student housing projects, and it is noted that the differences between different groups of students do not require new housing types than those otherwise mentioned in the report.

  • 157.
    Huc, Sabina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Hozjan, Tomaž
    Univ Ljubljana, Fac Civil & Geodet Engn, SI-1000 Ljubljana, Slovenia.
    Numerical analysis of moisture-induced strains and stresses in glued-laminated timberIn: Article in journal (Refereed)
  • 158.
    Huc, Sabina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Univ Boras, Fac Text Engn & Business, S-50190 Boras, Sweden.
    Hozjan, Tomaz
    Univ Ljubljana, Fac Civil & Geodet Engn, Ljubljana 1000, Slovenia.
    Svensson, Staffan
    Univ Boras, Fac Text Engn & Business, S-50190 Boras, Sweden.
    Rheological behavior of wood in stress relaxation under compression2018In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, no 3, p. 793-808Article in journal (Refereed)
    Abstract [en]

    Rheological behavior of wood under uniaxial compression along and perpendicular to the grain in constant environment was examined. Tests with constant deformation rate until failure and stress relaxation tests with constant deformation applied stepwise were carried out. The experimental results of stress relaxation showed nonlinear material behavior over time that got more prominent under high deformation levels. Considerable amount of stress relaxed during applying the deformation. Wood experienced greater stress relaxation along the grain than perpendicular to it. Three rheological models for orthotropic material were calibrated to the experimentally determined stress-time curves in longitudinal and transverse directions simultaneously. Small deformation levels assuming linear strains were accounted for in the models. Required elastic material parameters were determined from the tests with constant deformation rate. A model including the highest number of viscoelastic material parameters was the most successful in predicting stress relaxation of wood under stepwise deformation. Modeling indicated that wood behavior was very close to linear viscoelastic in relaxation under small deformation. The obtained material parameters made the model suitable for predicting rheological behavior of wood comprehensively, under sustained deformation or load in constant conditions.

  • 159.
    Huc, Sabina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Univ Boras, Fac Text Engn & Business, S-50190 Boras, Sweden.
    Svensson, Staffan
    Univ Boras, Fac Text Engn & Business, S-50190 Boras, Sweden..
    Coupled two-dimensional modeling of viscoelastic creep of wood2018In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, no 1, p. 29-43Article in journal (Refereed)
    Abstract [en]

    Three coupled two-dimensional viscoelastic creep models for orthotropic material are analyzed. The models of different complexity are mathematically formulated and implemented in a finite element software. Required viscoelastic material parameters are determined by calibration procedure, where numerical results are compared against experimentally obtained viscoelastic strains caused by tensile or shear loading. Finally, a comparison method is used to evaluate the accuracy of strain predictions of each particular model. The analysis shows that all the models are able to accurately predict viscoelastic creep simultaneously in two perpendicular directions for various periods of time and wood species. Calculated numerical values of the viscoelastic material parameters suitable for the three models and wood species, i.e., Douglas fir (Pseudotsuga menziesii), Norway spruce (Picea abies), Japanese cypress (Chamaecyparis obtusa), and European beech (Fagus sylvatica L.), under constant tensile loading are also given.

  • 160.
    Huc, Sabina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Svensson, Staffan
    Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Influence of grain direction on the time-dependent behavior of wood analyzed by a 3D rheological model: A mathematical consideration2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 10, p. 889-897Article in journal (Refereed)
    Abstract [en]

    A three-dimensional (3D) rheological model for an orthotropic material subjected to sustained load or deformation under constant climate has been mathematically formulated. The elastic and viscoelastic compliance matrices are symmetric, where the mathematical derivation of the latter is shown. The model is linear and requires constant numerical values for the elastic and viscoelastic material parameters. The model's ability to predict the natural time-dependent response in three material directions simultaneously is demonstrated on a Douglas fir (Pseudotsuga menziesii) specimen subjected to a constant uniaxial tensile load. The material extends in a longitudinal direction and contracts in the transverse directions with time. The required material parameters are taken from the literature when possible, otherwise they are assumed. Furthermore, the influence of misalignment between the directions of observation and wood material directions on induced time-dependent strains is analyzed. The analyses show that the misalignment has a large effect on the material behavior. In some cases, the specimen under constant uniaxial tension even extends in the perpendicular transverse direction with time. The obtained results clearly demonstrate the high importance of considering the alignment of material directions precisely in order to be able to interpret the time-dependent behavior of wood correctly.

  • 161.
    Huc, Sabina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Svensson, Staffan
    Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Hozjan, Tomaz
    Univ Ljubljana, Fac Civil & Geodet Engn, SI-1000 Ljubljana, Slovenia.
    Hygro-mechanical analysis of wood subjected to constant mechanical load and varying relative humidity2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 10, p. 863-870Article in journal (Refereed)
    Abstract [en]

    A hygro-mechanical (H-M) analysis of a wooden specimen sustaining a mechanical load while subjected to varying relative humidity was performed to predict the long-term rheological behavior of wood. The numerical analysis was based on the experimental results of total strains, monitored in two orthotropic material directions on oak wood specimens under constant uniaxial compression and with moisture content (MC) variation. For the moisture analysis, a multi-Fickian moisture transport model (MFMTM) was used to obtain temporal and spatial MC fields, which were the input data in the mechanical analysis. The presented mechanical model assumed a decomposition of the total strains into the elastic, viscoelastic and mechanosorptive strains and the strains due to shrinkage and swelling. The moisture and mechanical analyses required material parameters, which were taken from the literature or were empirically obtained by a fitting procedure. The performed H-M analysis gave accurate numerical predictions of the experimentally obtained total strains in two orthotropic directions simultaneously. Thus, the analysis developed has a high potential for predicting the long-term rheological behavior of timber structures, assuming that the material parameters are determined previously, based on specific, extensive, multidimensional experimental analyses.

  • 162.
    Hultgren, Olov
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Dammsäkerhetsanalys via stabilitetsberäkningar för Långströmmens kraftverk: En jämförelse mellan olika dimensioneringsmetoder2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A detailed dam safety evaluation (in Sweden called FDU) was performed in 2009 by WSP where stability control was performed for Långströmmen power plant with associated spillways. This evaluation concluded that stability could not be ensured, and risk of sliding occurred. The evaluation is based entirely on the recommendations outlined in RIDAS, the power companies guidelines for dam safety, and it is clear that extensive renovations are necessary to stabilize the dam.

    In this work, the stability will also be checked with guidance through new proposals on guidelines for concrete dams sliding stability, ELFORSK’s report 08:59. This report considered the guidelines in RIDAS as oversimplified, both from an international perspective, but also with regard to the current state of knowledge regarding dam safety. They also believe that RIDAS gives inconclusive results, since for some dams provide conservative results and for other dams result in the unsafe side. This report should therefore check the effect of calculating stability with use of the two dimension methods to get results that can then be analyzed for discussion regarding the appropriateness of using the new proposals on guidelines provided in ELFORSK.

    Via the use of ELFORSK requires that most material parameters are decided through further examinations of the rock in situ. These material parameters are then used to determine the shear strength of the interface between concrete and rock in the foundation section of the dam. Where the sliding safety be determined with respect to the contact surface both with and without the influence of adhesion.

    The results of the calculations through both RIDAS and ELFORSK are presented in the following report. Results are based on the screening of Långströmmen spillways, and one of its monoliths. The results show that for cases where no adhesion counted obtained results that do not meet standards of sliding stability. This also applies to the calculation under RIDAS which also shows results that do not meet standards of sliding stability. In the comparison of methodologies related to the need for tensioning cables to achieve the necessary safety against sliding, thus given results that are directly comparable because methodologies relate to different safety factors. In the event that the adhesion counted achieved results well on the safe side.

    For use of ELFORSK’s proposed new guidelines, there are no objections to not be able to use these. Whether to include the adhesion of the contact area is seen as risky as this assumes that the adhesion is constant and thus is not lost along the dam’s life. Whereupon this method, including adhesion, is recommended to not be included in the calculation.

  • 163.
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Biomechanical Analysis of Stress and Stiffness of New Load-Bearing Implants2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Medical implants are essential products for saving lives and improving life quality. Nowadays, the demand for implants, especially biocompatible and personalized ones, is increasing rapidly to deal with factors like congenital malformations, aging, and increasing prevalence of cancer. To facilitate their clinical applications, better understanding of their biomechanical properties is important. This thesis focuses on tubular and mandibular implants, and aims at studying stiffness properties and assessing stress distributions.

    Tubular implants with coupled helical-coil structure, which can be potentially used as tubular organ constructs, were manufactured by winding polycaprolactone filaments. Tensile and bending stiffnesses were evaluated through mechanical testing and finite element simulations. By increasing the number of helical coils, we could realize a new type of tubular implants which could be used in applications like trachea and urethra stents. Stiffness properties of such implants were investigated analytically, due to the geometrical periodicity. Through computational homogenization, the discrete mesh structures were converted to equivalent continua, whose structural properties were studied using composite beam theories. The numerical and analytical models developed can serve as tools for the mechanical design of implants.

    A patient-specific mandibular implant, additively manufactured of titanium alloys, failed shortly after surgery. The failure was studied using a numerical approach. Finite element models were generated from the 3D bone reconstructed from computed tomography data and implants processed by computational homogenization. The failure location and that of the numerically predicted largest von Mises stress agree well, which confirms the feasibility of using finite element simulations to quantitatively analyze implant failures and assist in implants design.

    For implant failures caused by local bone loss, analytical studies were also carried out to assess the stress distribution around screw-loaded holes in bones. The mandibular bone was treated as a laminate of which elastic properties were obtained by classical laminate theory. The stress profiles were predicted using a complex stress function method. The loading direction was found to have a minor influence on the stress distributions, while the friction coefficient has non-negligible influence. The stress state can serve as starting point to predict bone remodeling and be compared with criteria for bone strength.

    List of papers
    1. Parametric elastic analysis of coupled helical coils for tubular implant applications: Experimental characterization and numerical analysis
    Open this publication in new window or tab >>Parametric elastic analysis of coupled helical coils for tubular implant applications: Experimental characterization and numerical analysis
    Show others...
    2014 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 29, p. 462-469Article in journal (Refereed) Published
    Abstract [en]

    Coupled helical coils show promising mechanical behavior to be used as tubular organ constructs, e.g., in trachea or urethra. They are potentially easy to manufacture by filament winding of biocompatible and resorbable polymers, and could be tailored for suitable mechanical properties. In this study, coupled helical coils were manufactured by filament winding of melt-extruded polycaprolactone, which was reported to demonstrate desired in vivo degradation speed matching tissue regeneration rate. The tensile and bending stiffness was characterized for a set of couple helical coils with different geometric designs, with right-handed and left-handed polymer helices fused together in joints where the filaments cross. The Young's modulus of unidirectional polycaprolactone filaments was characterized, and used as input together with the structural parameters of the coupled coils in finite element simulations of tensile loading and three-point bending of the coils. A favorable comparison of the numerical and experimental results was found, which paves way for use of the proposed numerical approach in stiffness design under reversible elastic conditions of filament wound tubular constructs.

    Keywords
    Coupled helical coils, Finite element simulation, Structural stiffness, Tubular implants
    National Category
    Natural Sciences Engineering and Technology
    Research subject
    Engineering science with specialization in Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-218968 (URN)10.1016/j.jmbbm.2013.09.026 (DOI)000330085700042 ()
    Available from: 2014-02-20 Created: 2014-02-20 Last updated: 2017-12-06Bibliographically approved
    2. Elastic analyses of periodic rhombic mesh structures
    Open this publication in new window or tab >>Elastic analyses of periodic rhombic mesh structures
    (English)Manuscript (preprint) (Other academic)
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-262684 (URN)
    Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2015-10-27
    3. Applicability of a two-stage analytical model of the stiffness of mesh tubes
    Open this publication in new window or tab >>Applicability of a two-stage analytical model of the stiffness of mesh tubes
    (English)Manuscript (preprint) (Other academic)
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-262685 (URN)
    Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2015-10-27
    4. Failure location predictoin by finite element analysis for an additive manufactured mandible implant
    Open this publication in new window or tab >>Failure location predictoin by finite element analysis for an additive manufactured mandible implant
    Show others...
    2015 (English)In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 37, no 9, p. 862-869Article in journal (Refereed) Published
    Abstract [en]

    In order to reconstruct a patient with a bone defect in the mandible, a porous scaffold attached to a plate, both in a titanium alloy, was designed and manufactured using additive manufacturing. Regrettably, the implant fractured in vivo several months after surgery. The aim of this study was to investigate the failure of the implant and show a way of predicting the mechanical properties of the implant before surgery. All computed tomography data of the patient were preprocessed to remove metallic artefacts with metal deletion technique before mandible geometry reconstruction. The three-dimensional geometry of the patient's mandible was also reconstructed, and the implant was fixed to the bone model with screws in Mimics medical imaging software. A finite element model was established from the assembly of the mandible and the implant to study stresses developed during mastication. The stress distribution in the load-bearing plate was computed, and the location of main stress concentration in the plate was determined. Comparison between the fracture region and the location of the stress concentration shows that finite element analysis could serve as a tool for optimizing the design of mandible implants.

    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-262683 (URN)10.1016/j.medengphy.2015.06.001 (DOI)000361409100005 ()
    Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2017-12-04Bibliographically approved
    5. An analytical study of stress distributions around screws in mandibular bone
    Open this publication in new window or tab >>An analytical study of stress distributions around screws in mandibular bone
    (English)Manuscript (preprint) (Other academic)
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-262686 (URN)
    Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2015-10-27
  • 164.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Dérand, Per
    Department of Oral and Maxillofacial Surgery, Skåne University Hospital.
    Rännar, Lars-Erik
    Sports Tech Research Centre, Mid Sweden University.
    Hirsch, Jan-Michaél
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Oral and Maxillofacial Surgery.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Failure location predictoin by finite element analysis for an additive manufactured mandible implant2015In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 37, no 9, p. 862-869Article in journal (Refereed)
    Abstract [en]

    In order to reconstruct a patient with a bone defect in the mandible, a porous scaffold attached to a plate, both in a titanium alloy, was designed and manufactured using additive manufacturing. Regrettably, the implant fractured in vivo several months after surgery. The aim of this study was to investigate the failure of the implant and show a way of predicting the mechanical properties of the implant before surgery. All computed tomography data of the patient were preprocessed to remove metallic artefacts with metal deletion technique before mandible geometry reconstruction. The three-dimensional geometry of the patient's mandible was also reconstructed, and the implant was fixed to the bone model with screws in Mimics medical imaging software. A finite element model was established from the assembly of the mandible and the implant to study stresses developed during mastication. The stress distribution in the load-bearing plate was computed, and the location of main stress concentration in the plate was determined. Comparison between the fracture region and the location of the stress concentration shows that finite element analysis could serve as a tool for optimizing the design of mandible implants.

  • 165.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Applicability of a two-stage analytical model of the stiffness of mesh tubesManuscript (preprint) (Other academic)
  • 166.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Hirsch, Jan-Michaél
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Oral and Maxillofacial Surgery.
    Deránd, Per
    Lund University.
    Rännar, Lars-Erik
    Mittuniversitetet.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Finite Element Investigation of the In - Vivo Failure of a Titanium Alloy HumanJaw Implant2014Conference paper (Refereed)
    Abstract [en]

    In order to reconstruct a patient with a bone defect in the right lower jaw, a scaffold attached to a reconstruction plate, both in a titanium alloy, was designed and manufactured using three-dimensional printing technique. Regrettably the implant fractured in situ several months after surgery. This paper is orientated to investigate the reason for the implant’s failure and provide a way of predicting the mechanical properties of the implant before surgery. Preoperative, postoperative and implant-break computed tomography data of the patient were provided by the responsible surgeon. Metallic artifacts introduced by previous dental implants were removed with metallic deletion technique software beforehand. Three-dimensional volume of the patient’s jaw was thereafter reconstructed with trabecular bone removed based on the cleaned computed tomography data. The implant, screws and jaw were assembled together and meshed with triangular elements in Mimics 16.0. The assembly was imported into in-house software with surface mesh converted to linear tetrahedral mesh. Simulations were implemented under simplified but suitable loading conditions with the assumption that jaw was a linear elastic and homogeneous material. The stress distribution on the implant plate was calculated and the location of stress concentration on the plate was determined and then verified by the clinical data of the patient. This validated model could serve in the future as a tool for optimizing the design of jaw implants.

  • 167.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Hirsch, Jan-Michaél
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Oral and Maxillofacial Surgery.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    An analytical study of stress distributions around screws in mandibular boneManuscript (preprint) (Other academic)
  • 168.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Rojas, RamiroKTH Royal Institute of Technology.Bohlin, JanUppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.Hilborn, JönsUppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.Gamstedt, E. KristoferUppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Parametric analysis of stiffness properties of coupled helical coils for implant application2013Conference proceedings (editor) (Refereed)
  • 169.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Rojas, Ramiro
    Bohlin, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Gamstedt, E Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Parametric elastic analysis of coupled helical coils for tubular implant applications: Experimental characterization and numerical analysis2014In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 29, p. 462-469Article in journal (Refereed)
    Abstract [en]

    Coupled helical coils show promising mechanical behavior to be used as tubular organ constructs, e.g., in trachea or urethra. They are potentially easy to manufacture by filament winding of biocompatible and resorbable polymers, and could be tailored for suitable mechanical properties. In this study, coupled helical coils were manufactured by filament winding of melt-extruded polycaprolactone, which was reported to demonstrate desired in vivo degradation speed matching tissue regeneration rate. The tensile and bending stiffness was characterized for a set of couple helical coils with different geometric designs, with right-handed and left-handed polymer helices fused together in joints where the filaments cross. The Young's modulus of unidirectional polycaprolactone filaments was characterized, and used as input together with the structural parameters of the coupled coils in finite element simulations of tensile loading and three-point bending of the coils. A favorable comparison of the numerical and experimental results was found, which paves way for use of the proposed numerical approach in stiffness design under reversible elastic conditions of filament wound tubular constructs.

  • 170.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    van Dijk, Nico
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Elastic analyses of periodic rhombic mesh structuresManuscript (preprint) (Other academic)
  • 171.
    Huo, Jinxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Sandvik Min & Rock Technol, R&D Dept Min Tools, SE-81181 Sandviken, Sweden.
    van Dijk, Nico P.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Elastic properties of rhombic mesh structures based on computational homogenisation2018In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 172, p. 66-75Article in journal (Refereed)
    Abstract [en]

    Flat mesh structures are used in a wide variety of applications. In particular, meshes with a rhombic unit cell are frequently employed due to their simplicity and relative ease of manufacture. This paper studies the in-plane elastic properties of such a structure as a function of the geometrical parameters by means of homogenisation techniques. We compare predicted elastic in-plane properties (i) including only bending mode of the struts, cf. Gibson-Ashby model, (ii) including both bending and stretching modes of the struts, obtained by homogenisation using beam elements and (iii) by homogenisation using beam-spring elements accounting additionally for strut joint deformation, and (iv) numerical results of elastic properties obtained by homogenisation using solid elements. The expressions of the predicted elastic properties are presented in analytical form. The homogenised elastic properties accounting for both bending and stretching matches very well with those from the model including only bending. The axial deformation of struts thus has negligible impact on the overall elastic behaviour. The complex deformation in the strut joint was also captured in the homogenised using beam-spring elements, and the results agree better with the solid element results. It is concluded that a finite-element-based homogenisation approach could serve as a straightforward analytical method to obtain elastic properties of mesh structures. This approach automatically includes all deformation mechanisms as opposed to the classical unit cell analyses of bending beams.

  • 172.
    Husain, Musleh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    KONTROLLBERÄKNING AV ETT TAKRAS PÅ EN TENNISHALL I NYKÖPING: En jämförelse mellan Eurokod och BKR2013Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    “Boverket” the Design Regulations in Sweden, also called BKR has for a long time

    been the mandatory standard that has guided and regulated construction design. But

    at the end of 2010 BKR was replaced with Eurocode. This report deals with the

    comparison of these two standards when it comes to wood construction. During

    winter 2009/2010 there were many roof collapses due to excessive loads on the

    roofs across Sweden. The majority of these roofs were made during 1980 when BKR

    was the existing norm, therefore, this report will investigate whether there is a big

    difference between designing of such roofs according to Eurocode instead of BKR.

    These two norms were compared by looking at the design of roof structures that

    consist of beams and columns. The roof beam was checked for buckling which is

    designed to support the tennis center in Nyköping, and also a centrally loaded pillar

    holding up the roof beam and superimposed loads.

    The result of this investigation showed that to design according to Eurocode would

    be more substantively economically because the design load bearing capacity becomes

    slightly larger.

    It was also observed that, there isn’t a big difference between designing according to

    BKR or Eurocode, therefore these roof collapses couldn’t occur due to designing

    according to BKR. Designing according to BKR is even safer, but not substantively

    economically as Eurocode. A comparison between the results indicate that the slight

    difference is mostly caused by the the differences between the parameters/coefficients

    used for design.

    The roof collapse in Nyköping was caused by carelessness or ignorance, this tennis

    center is undersized.

  • 173.
    Huč, Sabina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Moisture-Induced Strains and Stresses in Wood2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To design safe, reliable and durable timber structures subjected to varying natural outdoor or indoor climates, understanding the long-term behavior of wood when mechanically loaded or restrained to deform is crucial. The present thesis focuses on the numerical modeling of the long-term mechanical behavior of wood. The numerical analysis is divided in the moisture transport and the mechanical analyses. In the moisture analysis, the multi-Fickian moisture transport model is used to determine spatial and temporal moisture content fields over the analyzed domain due to changing relative humidity (RH) of the ambient air. The obtained moisture contents are taken into the mechanical analysis where a new mechanical model is applied for predicting rheological response of wood in three orthotropic directions simultaneously. Experimental results of different authors are used to support numerous numerical analyses performed for various wood species, deformation and loading modes in constant or changing RH conditions. The performed analyses show that the new mechanical model adequately predicts the viscoelastic behavior of hardwood and softwood species in two orthotropic directions simultaneously under a sustained load or deformation. A significant influence of grain orientation in relation to the applied mechanical load on the viscoelastic creep behavior of wood is observed. The mechanical model is also able to predict accurately the rheological behavior of hardwood subjected to a sustained compressive mechanical load and changing moisture content. Applying the moisture and the mechanical models to the glued-laminated timber specimens during wetting and drying shows good agreement with the experimental results. The magnitudes of moisture-induced stresses perpendicular to the grain indicate a possibility of crack initiation during drying. The influence of characteristic material parameters required in the models on the mechanical state of the analyzed specimens is also determined. A quantification of the viscoelastic and the mechanosorptive material parameters required in the mechanical model is the additional outcome of the performed numerical analyses. The mechanical model presented in this thesis in combination with the multi-Fickian moisture transport model enables a full two- or three-dimensional long-term mechanical analysis of timber members exposed to natural climate with RH variations.

    List of papers
    1. Coupled two-dimensional modeling of viscoelastic creep of wood
    Open this publication in new window or tab >>Coupled two-dimensional modeling of viscoelastic creep of wood
    2018 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, no 1, p. 29-43Article in journal (Refereed) Published
    Abstract [en]

    Three coupled two-dimensional viscoelastic creep models for orthotropic material are analyzed. The models of different complexity are mathematically formulated and implemented in a finite element software. Required viscoelastic material parameters are determined by calibration procedure, where numerical results are compared against experimentally obtained viscoelastic strains caused by tensile or shear loading. Finally, a comparison method is used to evaluate the accuracy of strain predictions of each particular model. The analysis shows that all the models are able to accurately predict viscoelastic creep simultaneously in two perpendicular directions for various periods of time and wood species. Calculated numerical values of the viscoelastic material parameters suitable for the three models and wood species, i.e., Douglas fir (Pseudotsuga menziesii), Norway spruce (Picea abies), Japanese cypress (Chamaecyparis obtusa), and European beech (Fagus sylvatica L.), under constant tensile loading are also given.

    Place, publisher, year, edition, pages
    SPRINGER, 2018
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-341318 (URN)10.1007/s00226-017-0944-3 (DOI)000419587400002 ()
    Available from: 2018-02-07 Created: 2018-02-07 Last updated: 2019-01-28Bibliographically approved
    2. Rheological behavior of wood in stress relaxation under compression
    Open this publication in new window or tab >>Rheological behavior of wood in stress relaxation under compression
    2018 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, no 3, p. 793-808Article in journal (Refereed) Published
    Abstract [en]

    Rheological behavior of wood under uniaxial compression along and perpendicular to the grain in constant environment was examined. Tests with constant deformation rate until failure and stress relaxation tests with constant deformation applied stepwise were carried out. The experimental results of stress relaxation showed nonlinear material behavior over time that got more prominent under high deformation levels. Considerable amount of stress relaxed during applying the deformation. Wood experienced greater stress relaxation along the grain than perpendicular to it. Three rheological models for orthotropic material were calibrated to the experimentally determined stress-time curves in longitudinal and transverse directions simultaneously. Small deformation levels assuming linear strains were accounted for in the models. Required elastic material parameters were determined from the tests with constant deformation rate. A model including the highest number of viscoelastic material parameters was the most successful in predicting stress relaxation of wood under stepwise deformation. Modeling indicated that wood behavior was very close to linear viscoelastic in relaxation under small deformation. The obtained material parameters made the model suitable for predicting rheological behavior of wood comprehensively, under sustained deformation or load in constant conditions.

    Place, publisher, year, edition, pages
    SPRINGER, 2018
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-352579 (URN)10.1007/s00226-018-0993-2 (DOI)000430010200011 ()
    Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2019-01-28Bibliographically approved
    3. Influence of grain direction on the time-dependent behavior of wood analyzed by a 3D rheological model: A mathematical consideration
    Open this publication in new window or tab >>Influence of grain direction on the time-dependent behavior of wood analyzed by a 3D rheological model: A mathematical consideration
    2018 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 10, p. 889-897Article in journal (Refereed) Published
    Abstract [en]

    A three-dimensional (3D) rheological model for an orthotropic material subjected to sustained load or deformation under constant climate has been mathematically formulated. The elastic and viscoelastic compliance matrices are symmetric, where the mathematical derivation of the latter is shown. The model is linear and requires constant numerical values for the elastic and viscoelastic material parameters. The model's ability to predict the natural time-dependent response in three material directions simultaneously is demonstrated on a Douglas fir (Pseudotsuga menziesii) specimen subjected to a constant uniaxial tensile load. The material extends in a longitudinal direction and contracts in the transverse directions with time. The required material parameters are taken from the literature when possible, otherwise they are assumed. Furthermore, the influence of misalignment between the directions of observation and wood material directions on induced time-dependent strains is analyzed. The analyses show that the misalignment has a large effect on the material behavior. In some cases, the specimen under constant uniaxial tension even extends in the perpendicular transverse direction with time. The obtained results clearly demonstrate the high importance of considering the alignment of material directions precisely in order to be able to interpret the time-dependent behavior of wood correctly.

    Place, publisher, year, edition, pages
    WALTER DE GRUYTER GMBH, 2018
    Keywords
    grain direction, linear elasticity, linear viscoelasticity, material orthotropy, symmetry of compliance matrix, three dimensional rheological model, uniaxial tension, wood
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-363211 (URN)10.1515/hf-2017-0180 (DOI)000445777000008 ()
    Available from: 2018-10-17 Created: 2018-10-17 Last updated: 2019-01-28Bibliographically approved
    4. Hygro-mechanical analysis of wood subjected to constant mechanical load and varying relative humidity
    Open this publication in new window or tab >>Hygro-mechanical analysis of wood subjected to constant mechanical load and varying relative humidity
    2018 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 10, p. 863-870Article in journal (Refereed) Published
    Abstract [en]

    A hygro-mechanical (H-M) analysis of a wooden specimen sustaining a mechanical load while subjected to varying relative humidity was performed to predict the long-term rheological behavior of wood. The numerical analysis was based on the experimental results of total strains, monitored in two orthotropic material directions on oak wood specimens under constant uniaxial compression and with moisture content (MC) variation. For the moisture analysis, a multi-Fickian moisture transport model (MFMTM) was used to obtain temporal and spatial MC fields, which were the input data in the mechanical analysis. The presented mechanical model assumed a decomposition of the total strains into the elastic, viscoelastic and mechanosorptive strains and the strains due to shrinkage and swelling. The moisture and mechanical analyses required material parameters, which were taken from the literature or were empirically obtained by a fitting procedure. The performed H-M analysis gave accurate numerical predictions of the experimentally obtained total strains in two orthotropic directions simultaneously. Thus, the analysis developed has a high potential for predicting the long-term rheological behavior of timber structures, assuming that the material parameters are determined previously, based on specific, extensive, multidimensional experimental analyses.

    Place, publisher, year, edition, pages
    WALTER DE GRUYTER GMBH, 2018
    Keywords
    compression perpendicular to grain, mechanical model, mechanosorption, multi-Fickian moisture transport model, varying climate conditions, viscoelasticity, wood
    National Category
    Wood Science Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-363210 (URN)10.1515/hf-2018-0035 (DOI)000445777000005 ()
    Available from: 2018-10-17 Created: 2018-10-17 Last updated: 2019-01-28Bibliographically approved
    5. Numerical analysis of moisture-induced strains and stresses in glued-laminated timber
    Open this publication in new window or tab >>Numerical analysis of moisture-induced strains and stresses in glued-laminated timber
    (English)In: Article in journal (Refereed) Submitted
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-375147 (URN)
    Available from: 2019-01-28 Created: 2019-01-28 Last updated: 2019-01-28
  • 174.
    Hähle, Philip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Bengs Davies, Sebastian
    Etappsamordning: En studie för att effektivisera kommunikationen och samordningen vid stadsutvecklingsprojekt2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden, there are currently many ongoing city development projects that aim to improve the housing and work office situation. Due to the scope of these projects, they are generally divided into smaller stages. Within these stages there are many different entrepreneurs working on their own projects, but still share common ground for construction-related deliveries. However, there is currently a lack of incentive for the involved entrepreneurs to improve communication and coordination between themselves. The result of this leads to an increased difficulty to handle the logistics planning. As of late, some projects have an assigned work role, a stage coordinator, whose purpose is to communicate and coordinate with the involved entrepreneurs. However, the concept of this role hasn’t been sufficiently established within the construction sector yet. The concept is relatively new and because of this there hasn’t surfaced a proper working model yet.

    The purpose of this study is to examine and acquire knowledge about the underlying problems that reside between the entrepreneurs within the subject construction stage-coordination. The methodology of gathering information for the study was mainly carried out through interviews with professionals of the construction sector directly affiliated with the subject. Furthermore, the remaining information was gathered through literature about Lean, logistics and visual planning. Lastly, the remaining information were self-conducted study visits of affiliated stages.

    The results showed that there currently is very limited communication and coordination between the entrepreneurs. The respondents from the interviews claimed that there is a reluctance towards cooperating between the parties. The respondents explained that the reasoning behind this was that they wanted to conduct their own operations without having to involve other entrepreneurs. This usually leads to additional maintenance costs which they do not wish to be held accountable for, which they instead want the common client to be responsible over. However, they were positive towards utilisation of a visual planning software that could help them organize planning in-between themselves to help reduce unnecessary workload.

    When the conclusions for the above-mentioned information were made, the authors presented their own suggestions of how the visual planning software could be designed to alleviate communication and coordination in-between the entrepreneurs.

  • 175.
    Härd, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Skoglund, Mårten
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Trafikbelastade gårdsbjälklag: En undersökning av beräkningsmetoders lämplighet och möjliga förenklingar i projekteringsprocessen2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As a structural designer, you are sometimes required to design structures carrying traffic loads, but which are not, for example, bridges or parking garages. In practice, this usually applies to drivable floor layers and culverts under roads. When designing structures such as bridges and parking garages, there are clear standards and regulations to follow. These types of guidelines are not as comprehensive when it comes specifically to dimensioning traffic-load-bearing constructions in connection with building construction. Frequently, an evenly distributed load of 20 kN/m2 is used.

    The purpose of this work is to investigate which regulations house construction designers should relate to when designing structures that carry traffic loads which are not bridges or parking garages. The work also includes an investigation of how suitable different calculation methods are for different types of load cases. The goal is to make recommendations that can streamline the work for construction designers.

    The material for this work has been obtained through three different methods. In order to gain an understanding of the subject and the current state of knowledge in the field, a literature study has been made. The main part of the work has included qualitative interviews with people who have good experience and knowledge in the field, as well as practical modeling and calculation of load cases. The focus has been on investigating which transverse forces occur for some specific load cases. The study also includes the effect of the fill layer’s thickness on the load spread.

    For larger floor spans, it is confirmed that an evenly distributed load of 20 kN/m2 is a bit heaped. To dimension after this covers most of the load cases that may occur on a floor layer or similar construction. In some cases, this value could be halved without problem. It also turns out that the shorter the span of the floor, the more the evenly distributed load differs between the different fill layer thicknesses. 

  • 176.
    Håkansson, Lisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Dannfors, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    BIM i produktion: En undersökning om hur BIM kan implementeras  i produktion2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The object of this report is to investigate how to implement BIM into the production part of the construction industry. How NCC should act to make the transformation as smooth and easy as possible. BIM, Building Information Modelling, is a way of working where you gather all information in one place. All disciplines work in a 3Dmodel and have information about their component in that model. For example, you can create a specific wall with its different layers, that will make it easier to calculate offers from subcontractors and also make the daily work with other orders easier if you know what the wall is build of. You can also use the model for collision controles. This make everything more efficient and make it easier to collaborate between different disciplines.By interviewing people from the industry, mainly from the production, we found that there already are softwares on the market that NCC are using that is easy to use even if you haven't worked a lot with digital tools before. The problem is how to spread the information about these softwares so that more projects can use them. Another difficulty is how to get the craftsmen to use these softwares. The people we interviewed thought that the lack of interest for digital tools, and the older generation, is the main reason why the implementation will be challenging. Our conclusion is that NCC need to find a systematic way to educate their employees in the digital tools that they are using. They need to get better to spread the word about those digital tools within the company so that their employees understand how much they can help and will start to use them. The craftsmen should use the tools to help visualize what they are building and the on-site manager should have a software with more features.

  • 177.
    Håkansson, Maja
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Andersson, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Modellering av mark i beräkningsmodeller: En jämförelsestudie mellan tre beräkningsmetoder2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Computerized programs which perform calculations have developed rapidly over the past 30 years. The programs have progressed from performing basic calculations to more advanced ones which gives an opportunity to perform more accurate calculations. Even though advanced calculation programs exist, many calculations are still done by hand or in simple programs when designing foundations.

    The purpose of this thesis is to study the differences in results of ground pressure and settlements when using two different programs. The programs that have been used are WIN-Statik Foundation (which is an easier program) and FEM-Design (which is a more advanced program). Two methods are used to describe the soil in FEM-Design. The first involves springs with a predetermined stiffness (bedding modulus). The second method involves modelling the soil as a solid mass (3D-soil) along with the stratigraphy and its properties. The programs are evaluated from a usability point of view and how easy it is to understand the results, in order to understand why many construction engineers choose to use simpler programs than FEM-Design. The objective of the thesis is to produce a user manual for FEM-Design’s 3D-soil module to increase the usage of FEM-Design throughout the whole design process.

    Three different constructions have been modelled in order to perform the calculations: an individual footing, a group of three individual footings and a foundation slab. The results from the calculations were compared between the programs but also between the constructions. The comparison showed that FEM-Design with 3D-soil is recommended when preforming calculations of foundations placed close to each other. This is because the other methods do not take into consideration the impact the foundations have on each other. The biggest settlement of the foundation group more than doubled compared to the single foundation when the calculations were done with 3D-soil. The two other methods gave the same result of settlement for both constructions. When the foundation slab was calculated with 3D-soil the ground pressure became more than twice as big compared to the calculation with the bedding modulus. The advantage of WIN-Statik is that only a few input values are needed and the calculation is easy to perform. In most cases the simplification of the calculations in WIN-Statik creates bigger foundations than needed.

  • 178.
    Högberg, Robert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Holtug, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Skog eller gruva: En kostnads- och miljöjämförelse mellan limträ och stål som bärande stomme i en hallbyggnad2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis provides a cost and environmental comparison between an industrial building with glulam or steel as structural frame. Based on the project Kungsleden Industrihotell, by the company Kungsleden AB we make a comparison of two alternative bearing structures. The total length of the building is 96 meters and has a width of 25 meters. The dimensions of both a structural system frame of glulam and steel were calculated according to Eurocode standards. Based on this, the bill of materials has been calculated. Furthermore, for the quantities and dimensions of the two buildings, a cost calculation for materials, labour, fire protection and demolition have been performed. An environmental analysis with determination of carbon dioxide equivalent emission from production, transportation and recycling was carried out.

    The results of this thesis shows a price difference between the structural frame of the respective materials of about 200 000 SEK in the glulam's advantage. The simplified environmental analysis demonstrates that the glulam frame releases 1/3 of the equivalent carbon dioxide emissions in relation to the steel frame. 

  • 179.
    Höjenfält, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Larsson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Tidig dialog vid detaljplanering: Mindre kommuners möjligheter att föra en effektiv dialog med exploatörer2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden a requirement for a zoning plan is a must before any construction of larger scale can take place. The process leading up to a zoning plan has been criticized for being both time consuming and often leading to complications between the developer and municipality. There are a handful of factors to take in consideration, but the most prominent one is the lack of communication between developers and the municipality. This thesis is focused on trying to find the most suitable way to achieve a successful early dialogue between developers and municipalities before a zoning plan exists. Primarily on finding successful methods for smaller municipalities on how they should act when reaching out to developers and the most important factors for a successful thriving cooperation. By studying literature regarding the subject and carrying out interviews with both workers on the municipality- and developer side, different methods on how to implement an early dialogue and factors of great importance for a successful long-lasting cooperation was able to be established. Trust, competence, honesty and a smarter use of resources was pointed out as the most important factors according to the interviewed. With the different methods on how to establish an early dialogue, it is safe to say that there is no absolute way in telling which method a specific municipality should be using. Different municipalities are simply to unique with their own prerequisites and limitations. The right method for each municipality can only be found by trying them out.

  • 180.
    Isaksson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    A note on stress fields and crack growth in porous materials subjected to a contact load2015In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 64-65, p. 62-70Article in journal (Refereed)
    Abstract [en]

    In materials where inherent heterogeneities like cells and pores are relatively large compared to other relevant mechanical dimensions, such as the contact surface in indentation tests or the length of an existing crack, stress and strain fields predicted by classical continuum elasticity theories may become too harsh because of absence of internal lengths in the equations that characterize the underlying microstructure. To overcome this deficiency a gradient enhanced elasticity continuum theory may be applied, which include length parameters in the constitutive equations that limit the magnitude of deformation gradients and is able to capture internal length effects. In this study, microscopic stress fields in porous materials subjected to a cylindrical contact load are estimated with such a gradient enhanced continuum model. To judge the model's ability to capture the mechanical behavior in this class of materials, calculated stress fields in the contact region, given by the gradient theory, are contrasted with microscopic stress fields computed in discrete high-resolution finite element models of cellular wood-like structures having varying average pore sizes but identical macroscopic geometry and boundary conditions as the gradient model. X-ray computed tomography experiments on wood illustrate the phenomenon. It is observed, in both experiment and finite element models, that the region of high shear stresses, where a crack may grow despite a confining pressure, is located deeper down in the material than what is predicted in classical continuum theories. On the other hand, the gradient enhanced model produces remarkably similar stress/strain fields as the finite element models and experiment and is thus seemingly able to capture microstructural size effects.

  • 181.
    Isaksson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    A simplified probabilistic macroscopic model for estimating microscopic fracture development in idealized planar fiber network materials2012In: Mathematics and mechanics of solids, ISSN 1081-2865, E-ISSN 1741-3028, Vol. 17, no 4, p. 364-377Article in journal (Refereed)
    Abstract [en]

    The overall aim of this study is to derive a simplified probabilistic theory to reveal the 'hidden' mechanisms controlling random fracture evaluation in idealized network structures observed as diffuse material failure on the macro scale. The model is based on the classical theory of combinatorics and the practical implications for understanding material failure in network materials, such as non-woven felts made of nanofibers or glass fibers, is addressed. The simplified theory reveals a number of important results regarding the evolution of microscopic fractures in planar random fiber networks where the only active microscopic fracture mechanism is bond fracture and the network is loaded so that a homogeneous macroscopic mechanical field is present. A simple probabilistic expression is derived that estimates the fraction of fractured bonds achieved during the loading history. The equation includes a term for potential energy and assumes that there exists an inherent characteristic bond-strength parameter that is the same for all bonds. Subsequent finite element analyses confirm the simplified probabilistic theory and lend confidence in the rather rough assumptions made. The model is justified by observations in acoustic emission monitored tensile experiments performed elsewhere.

  • 182.
    Isaksson, Per
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Carlsson, L. A.
    Florida Atlantic Univ, Dept Mech Engn, Boca Raton, FL 33431 USA..
    Analysis of the out-of-plane compression and shear response of paper-based web-core sandwiches subject to large deformation2017In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 159, p. 96-109Article in journal (Refereed)
    Abstract [en]

    The mechanical response of three different structural core sandwich panels in out-of-plane compression and shear has been analyzed. Specific core shapes examined are arc-tangent, wavy trapezoidal and hemispherical. Unit cells consisting of representative elements of the core attached to face sheets were selected for analysis. Both face sheets and core were assumed made from paper. Finite element analysis employing large deformation and rotations and orthotropic elastic-plastic behavior was used. The results show that the arc-tangent and trapezoidal cores are prone to collapse by extensive bending and buckling, whereas the hemispherical core behaved more stably in compression and shear. Core sheets with a hemispherical shape were prepared from copy paper sheets in a specially designed forming machine. Sandwich test specimens were prepared from this core and tested in out-of-plane compression, and the load-displacement response was compared to predictions from finite element simulations. The experimental and finite element results were consistent.

  • 183.
    Isaksson, Per
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Dumont, P. J. J.
    Approximation of mode I crack-tip displacement fields by a gradient enhanced elasticity theory2014In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 117, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Gradient theories are capable of describing deformation of heterogeneous elastic materials better than classical elasticity theory since they are able to capture internal length effects. Here, crack-tip displacement fields at the tip of a mode I crack in gradient enhanced elastic materials are derived in closed form and contrasted with experiments. Heterogeneous materials, represented by discrete fiber networks, are analyzed in finite element models to judge the theory. It is shown that using a classical continuum approach to describe macroscopic singular-dominated deformation fields in heterogeneous materials lead to erroneous results because a structural effect that alters the displacement field becomes pronounced and results in severe blunting of crack-tips. A key conclusion is that the average segment length in the material gives the internal length scale parameter, used in the gradient enhanced continuum theory, hence allows for bridging between scales.

  • 184.
    Isaksson, Per