Boundary-Layer Effects in Composite Laminates: Part 1—Free-Edge Stress Singularities

A study of boundary-layer stress singularities in multilayered fiber-reinforced composite laminates is presented. Based on Lekhnitskii’s stress potentials and the theory of anisotropic elasticity, formulation of the problem leads to a pair of coupled governing partial differential equations (P.D.E.’s). An eigenfunction expansion method is developed to obtain the homogeneous solution for the governing P.D.E. ’s. The order or strength of boundary-layer stress singularity is determined by solving the transcendental characteristic equation obtained from the homogeneous solution for the problem. Numerical examples of the singular strength (or singular eigenvalues) of boundary-layer stresses are given for angle-ply and cross-ply composites as well as the cases of more general composite lamination.