Impact-induced deformation fields in 2D and 3D woven composites

The deformation fields and kinematics of woven composite material systems, due to impact loads, were analyzed and characterized for various structural and load parameters. Target plates comprising of woven composites with 3D and 2D preforms were considered. Kinetic energies in the range of 18–39,000 J, due to projectile velocities in the range of 2–1000 m/s, were investigated. The impact problem model accounts for geometrical details of the flat target plates and the hemispherical projectile. Contact solutions at dissimilar surfaces were modeled with gap elements, and the solution of the nonlinear dynamic problem was obtained by the finite element method. In the present study, we investigated wave propagation effects, and how their spatial and temporal distribution is related to the evolution of multi-dimensional elastic fields and potential damage modes. Unit cells representative of the 2D and 3D woven composites were used to obtain estimates of the overall elastic moduli. It was found that the compression wave induced by impact reflected several times between the free surfaces of the target plate before fiber failure initiated, and that this was one of the major mechanisms leading to penetration. At low velocity impact, the deformations were similar to quasi-static bending deformation modes, and failure is predicted to be due to fiber breakage at the backside of the target plate. At higher impact velocities, wave propagation effects are more significant and lead to penetration at the impact face. For all material systems, localized shear damage in 3D woven systems and extensive shear delamination in 2D woven systems preceded complete penetration.