Blast resistance of unidirectional fiber reinforced composites

Three-dimensional transient deformations of a laminate comprised of several unidirectional fiber reinforced layers perfectly bonded to each other and subjected to a blast load are analyzed by the finite element method with an in-house developed, verified and fully validated code with rate-dependent damage evolution equations for anisotropic bodies. The continuum damage mechanics approach employing three internal variables is used to characterize damage due to fiber/matrix debonding, fiber breakage, and matrix cracking. The delamination between two adjoining layers is assumed to ensue when the stress state there satisfies a failure criterion, and may initiate simultaneously at several points. The relative sliding between adjoining layers is simulated by the nodal release technique. The interaction among fiber/matrix debonding, fiber breakage, matrix cracking and delamination, and the possibility of their initiating concurrently at one or more points in the composite are considered. The effect of different material, geometric and loading parameters on the damage development and propagation, and the energy absorbed in each one of the four failure modes have been examined. These results give preliminary information on composite structure's design for maximizing the energy absorption and hence increasing structure's resistance to blast loads. The paper is a sequel to Hassan and Batra's paper [Hassan NM, Batra RC. Modeling damage development in polymeric composites. Composites B, doi:10.1016/j.compositesb.2007.02.001] wherein details of the damage evolution equations, verification of the code, and the validation of the mathematical model are given. (C) 2007 Elsevier Ltd. All rights reserved.