On simultaneous failure of cross-ply and angle-ply composite laminates

This paper presents a particular class of bidirectional laminated composites where all layers fail simultaneously. The loading conditions, laminate configurations and the corresponding failure envelopes for simultaneous failure are obtained for cross-ply and angle-ply laminates under in-plane loads. The stiffness and strength characteristics of the laminates are discussed based upon the concept of lamination parameters. The optimal laminate configurations to maximize the in-plane strength are also obtained using the Tsai-Wu criterion as a first ply failure strength criterion. The failure surfaces of the studied laminates in stress space and in strain space are drawn and the optimal configurations are then determined. It is shown that the existance of laminate configurations for simultaneous failure depends mainly on the loading conditions.