Impact-induced deformation fields in 3D cellular woven composites

Abstract

Abstract The deformation fields and kinematics of nonporous and porous three-dimensional (3D) woven composite material systems were analyzed and characterized under an incident impact energy of 560 J caused by a 78 g projectile at a velocity of 120 m/s. The analysis quantifies experimental observations of the effects of porosity on the impact resistance and behavior of 3D woven composites. The dynamic nonlinear impact solution was obtained by the finite element method, in which contact between the projectile and the target plate was modeled with gap elements. In the present study, we investigated the spatial and temporal evolution of multi-dimensional elastic fields and potential damage modes in the target plates. A unit cell, representative of the 3D woven composite, was used to obtain estimates of the overall elastic moduli. These estimates were then used with two material models to represent the porous system in the finite element analysis of the target plate. One material model, which had explicit geometrical distributions of 3D voids, was used in the impact region, and the other material model, which was based on a representation of smeared voids, was used in regions removed from the impact zone. The analysis indicates that wave propagation effects at the incident energy applied here are significant, and these effects can lead to projectile penetration at the impact face. Localized shear damage in the 3D woven system precedes penetration in both the nonporous and the porous systems. Experimental observations, which indicate that a porous system can dissipate more energy than the nonporous system before penetration, are found to be mainly attributed to the confinement of local damage fields, which emanate from the boundaries of the embedded voids.