High velocity impact of thick composites

Abstract

An impact/penetration model for thick composites was developed for predicting the response of thick composite targets subjected to high velocity impact of projectiles. The model was based on phenomenological observation from ballistic tests at impact velocity range of 610 - 1,830 m/s. Three mechanisms, each of which represents one of the three stages of the penetration process in sequence: (i) punching; (ii) fiber breaking; and (iii) delamination, were identified to have provided the major energy absorption of the penetration process, which accounts for the deceleration of the projectile. This model, based on a continuum approach, was built on the framework of an orthotropic constitutive behavior with stress-based failure criteria and a simplified degradation scheme. The three major failure mechanisms were modeled by three independent failure criteria. Damage of the composites was progressed using a degradation model of the failure of the composites. The model was implemented into a hydrodynamic finite element code. A one-way eroding contact algorithm with which composites could be eliminated from the model upon the occurrence of certain failure combination was utilized to facilitate the penetration calculations. Correlation between numerical modeling and available test parameters from several ballistic tests was acceptable.