Microscopic strain fields at crack tips in porous materials analyzed by a gradient-enhanced elasticity theory. (December 2016)

• Record Type: Journal Article
• Authors: Joffre, T.; Chen, S.; Isaksson, P.
• Is Part Of: Engineering fracture mechanics. Volume 168:Part A(2016)
• Page Start: 160
• Page End: 173
• Publication Date: 2016-12
• Subjects: Porous materials -- Fracture -- Gradient enhanced elasticity; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2016.10.005
• Languages: English
• ISSNs: 0013-7944

Abstract

Abstract: 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.