Analytical Model for Dynamic Yield Strength of Metal

Abstract

Strain rate effect of yield strength has been a hot topic for a long time in impact mechanics over decades, and it is important to explore the physical mechanism behind this phenomenon. In this study, a one-dimensional stress bar analytical model for the dynamic yield stress of metal materials under a sinusoidal stress wave pulse is presented based on the structural-temporal failure criterion, and the corresponding numerical results accord well with previous experimental data under the high strain rate. Moreover, the dynamic yield strength can be determined by the nondimensional parameters κ and χ as well as a material parameter α. Specifically, the first nondimensional parameter κ can be determined by the ratio between the loading amplitude and quasi-static yield strength. The second nondimensional parameter χ is calculated by the ratio between the loading period and the incubation time. 0herefore, the dynamic yield strength can be essentially determined by the quasi-static material parameters, incubation time and loading parameters. The so-called strain-rate effect on the yield strength should be treated as an interaction process parameter in a dynamic loading—material system and should not be considered as an intrinsic material property anymore. additionally, this study may help researchers to determine the parameters in the numerical models including the strain rate effect of the dynamic yield surface.