Numerical simulation of fatigue crack propagation in WC/Co based on a continuum damage mechanics approach

摘要

WC/Co referred also as hardmetal is one of the most widely used composite materials because of its high strength and wear resistance. The two interpenetrating phases of this advanced material have different mechanical properties: the brittle (elastic) WC phase contributes to the very high hardness whereas the ductile (elasto-plastic) Co phase contributes to the increased toughness of the material. There is a common agreement in literature that the hardmetals exhibit high fatigue sensitivity and the fatigue occurs predominantly in the ductile binder phase featuring ductile failure mechanisms. In this study the main focus was given to the numerical study of the microscale fatigue crack development in WC/Co. In this respect a damage model based on a continuum damage mechanics approach was implemented in commercial solver Abaqus/Explicit for simulating the crack propagation in the material. Separate damage laws based on brittle failure and fatigue are implemented for the WC and the Co phases, respectively. In order to evaluate the performance of the approach a numerical model based on a real damaged microstructure was generated. Based on the simulation results, the numerical model reflected strong agreement in comparison with the real crack pattern generated during the experiment. Results of this study indicate a strong dependence of the fatigue crack on accumulated plasticity within the binder phase; this suggests a novel understanding of the fatigue mechanism of this material and provides a basis for larger microstructural models.