THE GROWTH OF MICROVOIDS UNDER INTENSE DYNAMIC LOADING

This paper deals with the analytical study of the dynamic growth of microvoids. A previous model by Carroll and Holt (1972), Static and dynamic pore-collapse relations for ductile porous materials, J. Appl. Phys. 43, 1626 1636, for porous perfectly plastic materials under the action of a purely hydrostatic stress is further developed to include the influence of material viscosity, strain hardening and thermal softening in the tensile fracture behaviour. The results of this analysis are discussed with the help of a numerical study of the void growth relationships derived; the conclusion is that both material viscosity and strain hardening may have an important influence on the tensile strength of ductile materials at high strain rates. It is also shown that, in the conditions of the analysis, thermal softening by itself bas a negligible influence on the dynamic tensile strength at high strain rates due to excessively localized heat generation near the surface of the voids.