Abstract: To study the damage effects of mortar targets subjected to hypervelocity impact of kinetic-energy projectiles, the ogive-nose steel rods launched from a two-stage light gas gun were experimentally penetrated into mortar targets at 1 200-2 400 m/s. The linear dependences of cratering diameter and depth on the initial impact velocity are found from the experimental results. The penetration depth increases linearly first and then decreases sharply, and again increases slowly with the increase in impact velocity. Three penetration mechanisims, i.e., rigid penetration, semi-fracture penetration and fracture penetration, were observed,respectively, with the increase in impact velocity. A calculation model based on the internal friction penetration theory, in which the mass loss function of projectile is considered, is developed for predicting the penetration depths of rigid penetration and semi-fracture penetration. The calculated results were compared with the experimental results. The results indicate that the calculated results of the proposed model are in well agreement with the experimental results in terms of non-dimensional penetration depth. The special phenomenon of penetration depth reduction in the process of hypervelocity penetration is explained, and the inherent mechanism of variation law of penetration depth is further revealed.

Key words: mortartarget, hypervelocitypenetration, penetrationdepthreduction, massloss, penetrationmechanism