Mechanism on hypervelocity penetration of a tungsten alloy projectile into a concrete target

Abstract

To investigate the hypervelocity impact mechanism of a tungsten alloy projectile on a concrete target, a new dynamic plasticity-based failure model for metal was developed by introducing Lode angle, dynamic enhancement factor, temperature softening term and stress triaxiality, and a new constitutive model for concrete was proposed by introducing strain rate effect, pressure dependence, Lode angle and free water effect. The advanced measurement technologies were introduced to determine the dynamic mechanical behaviors of materials, then the materials parameters were used to numerically simulate the hypervelocity penetration of a tungsten alloy projectile into a concrete target. Based on a 57/10 two-stage light gas gun, the experiments were carried out on the hypervelocity impact of the tungsten alloy projectile on the concrete target. And according to the computed tomography scanning images of the damaged concrete targets, the crater characteristics in the targets were analyzed. Then the relationships of the total penetration depth and the residual length of the projectile with the initial impact velocity of the projectile were obtained. The penetration of the projectile and the stress wave propagation in the concrete target were analyzed by the theoretical method. The achieved results are as follows. (1) By utilizing the new constitutive models for the metal and concrete, the failure morphology of the concrete derived from numerical simulation is consistent with that from the experiment. (2) The craters are structured by spalling areas and projectile holes, the transverse failure effect shows a significant advantage over low-velocity penetration, and the volume of craters is approximately proportional to the kinetic energy of projectiles. (3) The penetration depth increases at first and then decreases with the increase of the impact velocities, the decrease of the penetration depth under high velocity is due to the decrease of the rigid penetration stage after the erosive penetration stage. (4) A theoretical penetration model is proposed, which can be used to predict the depth of penetration, the residual length of the projectile and the diameter of the mushroom-like head, et al. (5) A theoretical stress wave propagation model is developed and the theoretical results of stress waves are in good agreement with the experimental ones.