Cavitation impact damage of polymer: A multi-physics approach incorporating phase-field

Abstract

The challenge of material surface damage and spalling, caused by high-frequency, high-pressure jets owing to cavitation, remains a substantial concern. To better understand the physical mechanisms of cavitation-induced cyclic impact, we developed a multi-field-coupling framework. This framework encapsulates polymer viscoelastic-viscoplastic deformation, thermal softening, strain softening, and damage evolution represented by phase fields, which are crucial processes in cyclic impact. Particularly, we achieved full coupling between these key physical processes by introducing appropriate functional forms. We emphasize the need to include both plasticity and viscosity in the energy-driving crack propagation, to accurately represent the accumulation of polymer fatigue damage. With this thermodynamically consistent, fully coupled model, we could simulate surface ring cracking, a phenomenon often observed experimentally under cyclical impact loading. In the context of this particular crack morphology, we also discerned distinct fatigue failure mechanisms when variables such as strength, the radial extent of the cavitation impact load, and others were altered. We propose that a key determinant of cavitation flow impact is the combined effect of thermal softening, strain softening, and phase-field degradation within the polymer. Understanding these mechanisms offers a deeper insight into cavitation damage and provides a theoretical basis for cavitation-resistant design.