Numerical Simulation of the Protection System of Explosive Reaction Armor

There are some extreme conditions in the process of metallic jet penetrating the explosive reaction armor (ERA), such as high instantaneity, large deformation, et al. Based on the smoothed particle hydrodynamics (SPH) method, the generalized density approximate formula is proposed and the Held criterion is introduced. Then the numerical SPH model of metallic jet penetrating the explosive reaction armor is built to study its protection mechanics. The calculation result meets well with the theoretical value. The influences of some parameters, such as thickness of plate and attacking angle, on the protecting effect of explosive reaction armor are analyzed, aiming at providing references for the related engineering application. Keywords-numerical simulation;ERA; protection mechanics; SPH; generalized density approximate I. INTRODUCTION The explosive reaction armor (ERA) (1), which consists of a sandwich explosive and two plates, can considerably decrease the penetration and damage effects of the metal jet by cutting it continuously under the explosion of the sandwich explosive and the movement of plates (2). Most research on the explosive reaction armor (ERA) at present is based on the simulation using the finite element software, such as LS-DYNNA (3-5). Some relevant experiments are also conducted to study the protection effect of the ERA (6-8). However, the numerical methods based on finite element mesh need to estimate expansion of the detonation products before calculation, and then dimension of background mesh can be set. The excessive mesh domain will lead to the great increase of calculation amount while the smaller one may cause the larger calculation result error. Meanwhile, another question in the application of finite element software for the simulation of ERA is the impact detonation of the sandwich explosive. However, the defects of finite element methods mentioned above can be properly solved by the smoothed particle hydrodynamics (SPH) method (9). So the numerical simulation model of the explosive reaction armor (ERA) under the impact of metal jet is built using the SPH method to study the protection mechanism of the ERA.