Numerical Simulation of Spall Behavior of Metal Under Strong Impact Loading

When the metal material undergo complex loading processes, such as strong impact loading, unloading, backward drawing and reloading, they are likely to spall in the reverse tension stage. In this paper, the following four items are considered in the modeling of material spallation:(1) the damage variable in the spallation modeling adopts the concept of porosity; (2)the equation of state containing hole material is calculated by the solid component in the damage unit;(3) when the porosity of the unit reaches the critical porosity, it is considered that the pores are interpenetrated with each other to form a macro crack, and the material is fractured as a whole; (4) When the macro fracture unit is compressed again, if the average compression ratio of the unit reaches the closed critical value, it is considered that the unit is compressed into holed hole. In the existing the two dimension Lagrange fluid dynamics program, we have added the hole fracture growth, polymerization and collapse effect of spallation processing function, and verify the model and program code through a numerical example. The damage evolution analysis of the unit near a single measuring point shows that the platform area in the velocity curve corresponds to the damage fracture zone in the metal. It is considered that the unit of the location has undergo the physical process of unload-stretching-damage fracture -free flight-recompression. (C) 2018 The Authors. Published by Elsevier B.V.