HGA Approach for reliability-based design optimization of non-linear composite structures

Abstract

An approach to reliability-based design of beam reinforced composite shell structures with non-linear geometric behaviour is proposed. The formulation involves probabilistic stress, displacement and buckling constraints. The structural integrity is evaluated through the reliability index. The random variables are the mechanical properties of laminates considered as homogeneous orthotropic materials. A new methodology based on a genetic algorithm (GA) and a hierarchical decomposition searching the global most probable failure point (MPP) is presented. Simultaneously the optimal design is searched through a hierarchical genetic algorithm (HGA) based on weight/cost minimisation under prescribed reliability constraints. The design variables are the ply angle, the ply thickness, the height and the width of the cross sections of the stiffeners. Numerical examples of the new proposed developments are presented.