The Influence of Ply Waviness with Nonlinear Shear on the Stiffness and Strength Reduction of Composite Laminates

Abstract

The influence of ply waviness with nonlinear shear material response on the mechanical performance of composite laminates is studied. An analytic model, based on a three-dimensional laminated media analysis, is developed to predict the effective nonlinear laminate behavior associated with ply waviness. An undulating [0] ply in a [90/0/90] sublaminate configuration and undulating [±β] plies in a [90/±β/90] sub laminate configuration are two types of ply waviness considered. An incremental loading strategy is employed wherein piece-wise linear solutions are superimposed to obtain the overall nonlinear stress/strain response of composite laminates with wavy plies. The anal ysis also predicts individual ply stress and strain distributions within the wavy ply con figuration. The maximum stress failure criterion is used to predict ply failure in local re gions within the wavy ply configuration and a progressive failure methodology is adopted to permit local load redistribution. Results are presented that offer fundamental insight into the dominant mechanisms for stiffness and strength reduction in composite laminates exhibiting ply waviness and nonlinear shear material behavior.

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