A CONTINUUM DAMAGE MECHANICS MODEL OF THE MICRODAMAGE PROCESS ZONE DURING CORTICAL BONE FRACTURE

During fracture, cortical bone develops a large micro-damage process zone, which is thought to be vital to bone's intrinsic fracture toughness. Willett et al. (2017) measured the micro-damage process zone using micro-computed tomography and barium sulphate staining after sub-critical loading of single edge notch (bending) (SEN(B)) specimens. Recently, we sought to provide a computational model of this important mechanism. A finite element (FE) model of a SEN(B) specimen was developed in ABAQUS using continuum damage mechanics (CDM) to simulate non-linear behavior due to micro-damage. Elastic behavior was modeled as linear, transversely isotropic. Micro-damage initiation was incorporated using the Hashin failure criterion. Failure behavior was modeled using a damage law based on fracture energies. CDM-FE can model the micro-damage process zone with good fidelity if relatively high viscous regularization settings are used. The process zone was found to mimic that measured experimentally. The load-deflection curve from the FE model was similar to experimental curves within <3% error. CDM-FE may be a robust means for modeling micro-damage in cortical bone with potential application towards understanding how bone quality affects fracture. (C) 2018 Elsevier Ltd. All rights reserved.