Experimental and Numerical Investigation of Cyclic Creep and Recovery Behavior of Bovine Cortical Bone

Abstract An experimental and numerical study of the creep behavior of the bovine metatarsal cortical bone is presented. The experimental procedure included the multiple cycle tensile creep-recovery tests at eleven creep stress levels between 20 and 120 MPa. The threshold values of stress above which viscoplastic strain and damage start to accumulate are determined. Furthermore, based on the experimental data, a one-dimensional constitutive model has been developed. We demonstrate that Abdel-Tawab's viscoelasticity/damage model combined with the viscoplastic model proposed by Zapas and Crissman can predict the nonlinear behavior of cortical bone tissue subjected to creep-recovery loading conditions. Within the framework of numerical investigations, an efficient algorithm for the integration of the proposed constitutive model at the material point level is derived and implemented into the finite element software ABAQUS using user subroutines. The computational algorithm shows a good capability to describe the tensile behavior of bovine cortical bone for the specific mechanical conditions analyzed.