Modelling fracture process in a ductile solid under intense impulsive loading using a model of the void growth with temperature-dependency

Abstract

A model of void growth under intense impulsive loading, in which the thermal effect due to high rate of deformation, the inertial effect and rate-sensitive effect are taken into account, is incorporated in a Lagrangian finite-difference dynamic code to model the fracture process in a ductile solid, copper. Plate impact tests are performed for modelling the dynamic damage and fracture process of copper. Microscopic observations of mechanisms of growth and coalescence of voids in a softly recovered specimen are carried out. Computations of fracture process include the nucleation, growth and coalescence of voids. Numerical results show that in the damage cells, voids nucleate unceasingly as long as the tensile stress is greater than the threshold tensile stress σ n in the matrix material as larger voids are growing. Interaction of voids is considered by void nucleation and thermal effect indirectly. One of the major results of temperature-dependency in the model of the void dynamic growth is that the experimentally measured value of the viscosity coefficient η can be used to simulate the behaviour of damage and fracture in ductile solids. A few parameters in the model need to be determined, hence making the model of dynamic damage used in the present work easy to be applied to practical problems. Some computational details are discussed. A comparison of predicted location, and shapes of one and two dimensional spall surfaces in the targets with the experimental data seems reasonably good.