Accurate prediction of three-dimensional free edge stress field in composite laminates using mixed-field multiterm extended Kantorovich method

Abstract

An accurate prediction of the three-dimensional (3D) and often singular stress field at the free edges of composite laminates has been the subject of intense research since the pioneering numerical work of Pipes and Pagano (J. Compos. Mater. 4:538–548, 1970). In this work, we present an accurate 3D elasticity-based solution for determining the free edge stress field in laminates under uniaxial extension, bending, twisting and thermal loading, using the mixed-field multiterm extended Kantorovich method (MMEKM), which is a powerful iterative analytical method, developed recently by the author group. Unlike the existing 3D elasticity-based solutions, the present solution satisfies all the boundary conditions and the interfacial continuity conditions exactly at all points. The results are compared with various existing solutions reported for symmetric cross-ply and angle-ply laminates. New results are presented for the free edge stress field in antisymmetric angle-ply laminates for the four different load cases. The results show a rapid convergence and excellent accuracy of the MMEKM solution in all cases. The solution successfully captures the stress singularity at the free edge by predicting a steadily increasing peak value with increasing number of terms. The presented results will serve as useful benchmarks for assessing the accuracy of other approximate 3D and 2D theory-based solutions.