COMPARATIVE-EVALUATION OF DIFFERENT OPTIMIZATION ALGORITHMS FOR STRUCTURAL DESIGN APPLICATIONS

Non-linear programming algorithms play an important role in structural design optimization. Fortunately, several algorithms with computer co des are available. At NASA Lewis Research Centre, a project was initia ted to assess the performance of eight different optimizers through th e development of a computer code CometBoards. This paper summarizes th e conclusions of that research. CometBoards was employed to solve sets of small, medium and large structural problems, using the eight diffe rent optimizers on a Cray-YMP8E/8128 computer. The reliability and eff iciency of the optimizers were determined from the performance of thes e problems. For small problems, the performance of most of the optimiz ers could be considered adequate. For large problems, however, three o ptimizers (two sequential quadratic programming routines, DNCONG of IM SL and SQP of IDESIGN, along with Sequential Unconstrained Minimizatio ns Technique SUMT) outperformed others. At optimum, most optimizers ca ptured an identical number of active displacement and frequency constr aints but the number of active stress constraints differed among the o ptimizers. This discrepancy can be attributed to singularity condition s in the optimization and the alleviation of this discrepancy can impr ove the efficiency of optimizers.