First-Ply Failure Analysis of Bioinspired Double and Cross-Helicoidal Laminated Sandwich Plates

Inspired from the helicoidal schemes available from biological creatures, the present paper aims to predict the first-ply load for laminated composite and sandwich plates inspired from biological creatures. The laminated composite and sandwich plates are assumed to be made up of double- and cross-helicoidal lamination schemes. The first-ply failure load is determined using the recently proposed higher-order zigzag theory. Five different failure criteria (namely, maximum stress, maximum strain, Tsai-Hill, Tsai-Wu, and Hoffman's theory) are used to predict the first-ply failure load. The performance of the helicoidal plate is compared with the cross-ply and quasi-isotropic lamination schemes. The influences of the end conditions, the ratio of the thickness of the core to the face layers, and the thickness-to-side ratio on the first-ply failure load are carried out. It has been observed that for helicoidal plates, a higher value of the first-ply failure load is observed as compared to quasi-isotropic and cross-ply laminates, especially for plates having free edges. The maximum strain theory should not be used for predicting the failure load for helicoidal laminated plates because it undermines the strength of the plate.