Free-Edge Interlaminar Stress Analysis of Composite Laminates Using Interface Modeling

Abstract

Interlaminar stresses near free edges in composite laminates were analyzed by considering interface modeling. Previous regular analytical solutions for free edge stress are not rigorous in their linear elastic modeling with dissimilar interfaces between homogeneous plies of laminated composites. Singular stress is not practical in reality at the free edge because it nearly never occurs in real situations. Until now, the analytical nonsingular approximate solutions have been accepted even though they cannot show the rigorous singular behavior at the free edges; this shortcoming is corrected within linear elasticity dissimilar interface modeling. In this study, a regular analytical solution is provided, which is rigorous within the linear elastic model featuring smoothly varying material properties through the thickness of the laminates. This interface modeling provides not only nonsingular stresses but concentrated finite interlaminar stresses using the principle of complementary virtual work and the stresses that satisfy the traction-free conditions not only at the free edges but also at the top and bottom surfaces of laminates are obtained. Significant reductions in stresses at the free edge were observed compared with the results without interface modeling. Various stress analyses were performed and the results demonstrate the usefulness of the proposed interface modeling.