Microscopic strain fields at crack tips in porous materials analyzed by a gradient-enhanced elasticity theory
2016 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 168, 160-173 p.Article in journal (Refereed) Published
The microstructural influence on the strain field at opening mode crack tips in porous materials, and especially its practical implication for understanding macroscopic failure, i.e. on a scale above, is investigated. Theoretical subscale microstrain fields are approximated using a gradient-enhanced elasticity theory and compared to microstrain fields computed in discrete high-resolution finite element microstructural models having varying pore densities but similar macroscopic geometry and boundary conditions as the theoretical gradient-enhanced model. The numerical elastic microstrain and microstress fields are non-singular in strong contrast to the singular macroscopic fields in classical linear elastic fracture theories. Experimentally approximated microstrain fields, estimated with a digital image correlation algorithm on images obtained in X-ray computational tomography fracture tests on a small wood specimen, are used to contrast the.numerical analyses. A key observation is that an internal length parameter, used in the gradient-enhanced model, seems to be linked to the average pore diameter, allowing for direct bridging between scales.
Place, publisher, year, edition, pages
2016. Vol. 168, 160-173 p.
Porous materials, Fracture, Gradient enhanced elasticity
IdentifiersURN: urn:nbn:se:uu:diva-311485DOI: 10.1016/j.engfracmech.2016.10.005ISI: 000389093900011OAI: oai:DiVA.org:uu-311485DiVA: diva2:1060580
FunderSwedish Research Council Formas, 232-2014-202