Contact elasto-plasticity of inhomogeneous materials and a numerical method for estimating matrix yield strength of composites

For inhomogeneous materials such as case carburized steels, the localized micro-plasticity is induced at the scale of the inhomogeneity even if the stress field is elastic at the global scale. The matrix yield strength is a critical measure of integrity of such materials but is largely unknown and difficult to be directly measured due to the disturbances from distributed inhomogeneities. A numerical method is proposed to estimate the matrix yield strength of an inhomogeneous material. This allows for extracting matrix yield strength of the carburized bearing steel M50-NiL. The results show that, the difference between the macroscopic yield strength and matrix yield strength is small, suggesting that the direct strengthening from carbides as particle reinforcement is limited.