FREE-EDGE EFFECTS IN ANISOTROPIC LAMINATES UNDER EXTENSION, BENDING, AND TWISTING .2. EIGENFUNCTION ANALYSIS AND THE RESULTS FOR SYMMETRICAL LAMINATES

The eigenvalue problem associated with the determination of the interlaminar stresses in a laminated strip is examined and physical interpretations are given to the (constant) particular solutions and the complementary solutions of the problem. The case of symmetric laminates is considered in detail, and variational solutions are computed for four-layer, symmetric, cross-ply, and angle-ply laminates subjected to the three fundamental types of strain loads. Solutions based on two sets of stress functions with polynomial expansions of different degrees are compared with each other and with the existing solutions to assess the accuracy. The interfacial values of the stress functions and their derivatives are identified as the resultant peeling and shearing forces over end intervals of the interface.