Minimizing Stress Concentrations in Laminated Composites by Genetic Algorithm

Design optimizations using a genetic algorithm (GA) are well suited for problems having many design variables and local optimum design points. Concomitant with recent manufacturing advances, the concept is utilized here to minimize the tensile stress concentration in a perforated laminated composite by orientating the fibers locally both within the plies and from ply-to-ply. The current optimization approach is advantageously conducted in conjunction with FEA. The geometry is discretized into general 3D solid 20-node isoparametric layered composite elements of our own design. Solid, rather than plate, elements enable one to reliably account for features such as stress variations within and between individual plies. A parallel computing scheme is implemented between the FEA and GA optimization. Design optimization variables are local fiber directions within discrete finite elements and within respective plies of the laminate. Since fiber orientations are optimized locally within individual plies, the technique provides more than just a favorable stacking sequence of various rectilinearly orthotropic plies having different fiber orientations.