AUTOMATIC SHAPE OPTIMIZATION OF 3-DIMENSIONAL SHELL STRUCTURES WITH LARGE SHAPE CHANGES

A finite element-based shape optimization program has been developed for three-dimensional shell structures which allows for large shape changes. The new shape optimization program has been achieved by linking together adaptive mesh generation, substructuring, and linear and nonlinear optimization techniques to a commercial finite element analysis program (MSC/NASTRAN). The program has the capability of optimizing shapes by allowing multiple edges to move. A new procedure was developed to determine the best edge to move at each iteration of the shape optimization. The position of this edge is then determined using nonlinear optimization techniques. This process is incrementally continued until the edges are at their minimum positions, or the change in objective function is less than a tolerance value. This program is presently being applied to weight minimization.