NUMERICAL MODELING OF NORMAL IMPACT ON CERAMIC COMPOSITE ARMORS

In this paper, the penetration of ceramic targets backed by thin metallic plates when impacted by cylindrical projectiles is studied. To achieve this, a two-dimensional axisymmetric numerical analysis of the normal impact problem is performed. The macroscopic material behaviour in the zone of finely pulverized ceramic ahead of the penetrator is modelled by means of a constitutive model taking into account internal friction and volumetric expansion. The amount of comminution at the computational cells is evaluated through a damage evolution equation, and the yield stress is assumed to be a function of the hydrostatic pressure, internal friction and amount of comminution. For the metallic materials involved, an elasto-plastic behaviour with a rupture condition was considered. Moreover, an erosion condition was included as a limit situation when the ruptured material limits its role in the penetration process to purely inertial effects. In this way, a detailed picture of the penetration process of the target by the impacting projectile was obtained. Then, the results of the numerical analysis were compared with the experimental observations of the projectile-target interaction, previously made by Reijer by using a flash X-ray technique. Under certain conditions, remarkable agreement between computations and experiments is encountered, thus suggesting the adequacy of the main assumptions made in the numerical approach to the physical situation.