PREDICTION OF FREE-EDGE STRESSES IN COMPOSITE LAMINATES USING FULL-LAYERWISE-THEORY-BASED FINITE ELEMENTS

This paper deals with the 3D analysis of free-edge stresses in laminated composite plates using Reddy’s full-layerwise-theory-based finite element model (FLWT-FEM). The theory assumes a piece-wise linear variation of all displacement components and quadratic variation of interlaminar stresses within each layer. The free-edge effects are related to singular stress states at the interfaces between dissimilar layers along the free edges of the laminar composite. Stress concentrations at free edges can further lead to delamination and the significant drop in stiffness, with failure occurring at lower loads than expected. Starting from the strong formulation of the FLWT, a family of layered finite elements has been derived and implemented in original object-oriented MATLAB code. Free-edge stress field under axial strain has been analyzed. A validation example of cross-ply composite has been presented, and the results are compared against the existing analytical solutions and those obtained using the commercial software. The accuracy of the model is verified, and the possibilities for the further improvement and applications are provided.