Parameter determination of JH-2 model and numerical analysis of repeated penetration of granite

Abstract:

To investigate the dynamic response of granite target plate under repeated penetration, the nonlinear dynamic software AUTODYN along with the FEM-SPH coupling algorithm was used to simulate granite penetration. First, JH-2 model parameters were preliminarily determined through theoretical analysis. Then, the parameters were adjusted and optimized according to the simulation results of single penetration experiment of granite. Finally, under the projectile velocity of 220 m/s≤V_s≤420 m/s, the repeated penetration of granite was simulated and analyzed by using the optimized parameters. Results show that the JH-2 model coupled with tensile fracture softening model could make up for the deficiency of the JH-2 model in describing the dynamic response of rocks in low stress zone due to the action of main tensile stress. The failure mode of “conical crater + tunnel” formed during the initial penetration of the granite target plate provided a prerequisite for the subsequent repeated and stable penetration. With increasing impact times, the absolute penetration depth gradually increased, while the relative penetration depth decreased. The higher the impact times or impact velocity was, the more stable the penetration process of the projectile was. In addition, the concept of relative penetration coefficient and the theoretical formula of repeated penetration depth based on impact times and projectile velocity were given, both of which have certain practical values.