modeling the plastic deformation of dense and porous biomaterials using modified yield criteria by lode angle

In this research, the von mises and gurson models were modified by incorporating the lode angle and void volume fraction to predict the mechanical behavior of materials with non-uniform geometry or porous (cellular) structures, where the stress state affects yield behavior. the yield functions were enhanced multiplying them by a function of the lode angle, and the voce model was employed to account for the hardening or softening of various materials. the material parameters of the voce model were determined by fitting the experimental data for steel, elk antler, polyurethane foam, and bioscaffold. to improve alignment with experimental data, the void volume fraction was treated as a function of the trace of the plastic strain tensor. it was observed that by varying the lode function parameters, different shapes for the yield surface were achieved, allowing for the selection of tailored yield function for specific materials. results of finite element (fe) constitutive modeling showed that by selecting an appropriate yield function and determining suitable values for the lode angle function parameters, the modified yield function can accurately predict the mechanical behavior of various materials. it was observed that the barreling of porous compressed materials depends on the porosity and friction.