Modeling of competition between shear yielding and crazing in amorphous polymers' scratch

An effective approach to investigate the complex scratch damage mechanisms of polymers, based on a suitable material constitutive model, is important to understand the damage evolution during scratch process. For the constitutive model capable of the description of the competition between shear yielding and crazing of amorphous polymers, a crazing initiation criterion was proposed. The scratch damage mechanisms of ductile polycarbonate (PC) and brittle poly (methylmethacrylate) (PMMA) were experimentally and numerically investigated. It can be found that, the shear yielding dominates the scratch process of PC, while the coexistence and competition between shear yielding and crazing are the main damage mechanisms for PMMA scratch. The effect of scratch velocity was also investigated. Those findings are helpful for the designing of scratch-resistant polymers.