First Ply Failure of Laminated Composite Plates - A Mixed Finite Element Approach

First-ply failure (FPF) analyses of composite laminated plates have been presented in this paper. A 3-D layer-wise mixed finite element model developed by the authors (Ramtekkar, G. S., Desai, Y.M. and Shah, A. H. (2002). Mixed Finite Element Model for Thick Composite Laminated Plates, Mechanics of Advanced Materials and Structures, 9(2): 133-156.) has been employed for the computation of components of stress and strain. FPF has been predicted by using the maximum stress, the maximum strain, Tsai-Hill, Tsai-Wu and Hoffman failure theories. It has been observed that the 3-D failure theories have yielded approximately the same failure load as their 2-D counterparts because the failure of a lamina (ply) under flexure is primarily associated with the in-plane stress state. It has been demonstrated that the present methodology predicts the FPF load for cross-ply laminated plates very well. Results have been presented for cross-ply-angle-ply, symmetric-anti-symmetric and thin-thick plates to show important observations.