Optimization with non-homogeneous failure criteria like Tsai–Wu for composite laminates

In designing composite laminates, minimization of a suitable failure criterion is sometimes selected as the objective function. However, for non-homogeneous criteria, e.g., the Tsai–Wu criterion, this objective function will not maximize the failure load, when it is carried at a load which is different from the failure load. We suggest that the use of a safety factor for the objective function is more appropriate for maximizing for the faiure load. In fact we show losses of more than 40% in the load carrying capacity even when the load carrying capacity of the optimal laminate is 75% of the applied load.