Optimum design for double-lap bolted composite joints using a genetic algorithm

This study demonstrates the application of the Genetic Algorithm (GA) to achieve an optimal double-lap bolted joint design with composite laminates. Bolt diameters and the spacing between the bolts along the length and width directions of the joint are considered as design variables. The contact stresses (bolt loads) are determined by a combined complex potential and variational formulation. In this formulation, the equilibrium equations are satisfied exactly and the boundary conditions are enforced by minimizing the total potential. The contact stresses, as well as the contact region, are determined through an iterative procedure as part of a solution method that accounts for the effects of finite geometry and by-pass loading. Failure stress and its mode are predicted by employing the point stress criterion, thus providing the means for the evaluation function necessary in the application of the GA.