Modeling of Material Response

Abstract

In this chapter, a model is proposed for analyzing the response of ductile materials to repetitive cavitation impacts. This model emphasizes those impacts whose amplitudes exceed the material rupture strength and cause material fracture and mass loss. Impacts whose amplitudes are between the material yield stress and rupture strength are assumed to progressively harden the superficial layers of the material and contribute to the erosion acceleration period. The hardening mechanism is described on the basis of hardness profiles measured on cross sections of eroded samples. In particular, a characteristic thickness of the hardened layers is introduced. The model leads to a simple equation for the prediction of the erosion rate during the steady-state period. The equation shows that it is proportional to the characteristic erosion rate defined as the ratio of the hardened layer thickness to the impact coverage time. This approach tends to prove that the length scale and time scale relevant to the erosion process are respectively the hardened layer thickness (mostly a material property) and the impact coverage time (mostly a flow property).