Effects of curvature on high-velocity impact resistance of thin woven fabric composite targets

As structural elements with shielding requirements often feature nontrivial curvatures, their effective use in many engineering applications must undergo a precise evaluation of the effects of curvature on their resistance to impacts. In this work, an analytic formulation aimed at estimating the effects of curvature on the ballistic limit of thin woven fabric composite targets given their mechanical and geometric properties, as well as the projectile shape and initial velocity, is proposed. The described approach consider two-dimensional woven fabric composites and is based on wave propagation theory. The energy transfer occurring from the projectile to the target encompasses various energy-absorbing mechanisms. The tensile deformation of the yarns beneath the impact area, the tension and bending-induced deformation of the yarns constituting the region surrounding the impacted zone, the delamination onset and propagation and matrix cracking are considered in the model. The conical deformation on the back face of the composite target as result of the impact and the shear-driven generation of a plug are also taken into account. Ballistic limit, damage size and impact duration are then obtained through enforcement of the energy balance, showing that a nontrivial correlation exists between the curvature and the impact resistance of the target. (C) 2016 Elsevier Ltd. All rights reserved.