Discrete optimization of composite structures under fatigue constraints

An optimization design methodology of composite materials and structures subjected to fatigue life constraints is presented and discussed in the paper. It is assumed that laminates are made of plies having three different fiber orientations: 0°, ±45°, 90°. A special type of new, discrete design variables is introduced in order to find optimal stacking sequences for laminated structures. The results of the optimization of buckling loads for compressed plates are demonstrated herein. The accuracy of the prediction procedure depends directly on the selected stiffness degradation model based on the experimental data. The existence of fatigue constraints may change both optimal stacking sequences and buckling modes.