EXPLOITING DESIGN LENGTH SCALES IN STRUCTURAL OPTIMIZATION

Many structural optimization methods use geometric length scales as well as artiÞcially imposed lengths such as Þnite element dimensions. One considers functions deÞned over these dimensions in characterizing and solving the problem. The natural length scales involved in the proposed design change are generally overlooked. When one proposes an optimization based on change of certain panels in a sheet metal structure, for instance, it might be helpful to use the dimensions of the redesign areas as characteristic lengths. In the present study, a RayleighÐRitz approach is taken where the responses of a structure to pseudo-loads (acting only over speciÞed design-change regions) are employed as basis vectors. It is found that convergence of the optimization process is improved. The method is demonstrated for moderate-sized problems, and as with other modal methods, should become even more helpful for large problems. The new complexity involved is the requirement for a type of problem-dependent linking, in parallel with the conventional design variable linking. This can be automated