Nonlinear Progressive Failure Analysis Of Thick Composite Laminate Under Biaxial Load

Because of the high performance,fiber-reinforced composites have been widely used in aircraft structures. Thick laminate component emerged as important part of aircraft structure since more and more composites were used in the primary structure of aircraft. How to solve the the problem that classical laminate plate theory becoming inaccurate for determining stress response of thick laminate stucture, coupled with the non-linear behavior has become the key point of application of thick laminate stucture.Firstly, Accurate strength analyses, which contains four steps: choosing the constitutive model, obtaining the stresses response, picking failure criteria and determining the degradation method, was reviewed in this paper. Finally, an incremental solution method was applied based on thick laminate theory coupled with non-linear constitutive model for progressive failure calculation under biaxial load of thick composite laminates. 3D Hashin criterion was employed to predicting the failure of individual ply in the laminates. Degradation was applied when failure was predicted and the stiffness of laminates is updated step by step during the incremental solution. A program written in PCL (Patran Command Language, the secondary development language of commercial FEM software MSC.Patran) was employed to analysis the nonlinear stress-strain variation for different laminates with different materials. The process of progressive stiffness analysis supplies foundations of theory and calculation for stiffness variation analysis during failure process of thick composite laminates. The initial failure and final failure envelop were acquired with varied materials, lay-up and load-ratio, which excellent demonstrated the process of progressive failure and is of great significance to investigation of the failure and failure process of thick composite laminates under biaxial load.