Optimum design of structures with multiple constraints

Automated design of large aerospace structures requires efficient optimization algorithms because of a large number of design variables and design constraints. Most of the difficulties associated with large structural design are solution convergence and computer resources requirements. Practical aerospace structures generally involve limitations on gage sizes, displacements, stresses, and frequencies. The objective of this study was to determine what techniques are reliable and efficient for optimization of a complex design problem. The study examined the relative numerical performance of various optimization methods as candidates for a hybrid algorithm using optimality criteria and mathematical programming methods. Several optimization programs were used to design truss- and wing-type structures, and the iteration history for each technique is presented. The computer programs using the method of feasible directions and a modified Newton's method of unconstrained minimization were the most reliable mathematical programming methods.