Shape Optimization

An optimization method wherein the outer boundary of the structure is modified to solve the optimization problem.

Using finite element models, the shape is defined by the grid point locations and shape optimization modifies these locations to update the shape.

Shape variables are required to implement shape optimization. Each shape variable is defined by using a DESVAR Bulk Data Entry. If a discrete design variable is desired, a DDVAL Bulk Data Entry needs to be referenced for the design variable values. DVGRID Bulk Data Entries define how much a particular grid point location is changed by the design variable. Any number of DVGRID Bulk Data Entries can be added to the model. Each DVGRID Bulk Data Entry must reference an existing DESVAR Bulk Data Entry if it is to be a part of the optimization. The DVGRID data in OptiStruct contains grid location perturbations, not basis shapes.

The OUTPUT, DVGRID option creates shape variable definitions for displacement or eigenvector results of linear static, normal modes, or linear buckling analyses. These shape variable definitions can then be used in subsequent optimizations. This process facilitates the use of "natural" shape functions.

The generation of the design variables and of the DVGRID Bulk Data Entries is facilitated by the HyperMorph utility, which is part of the HyperMesh software.

Shape optimization is typically applicable for both small and large shape changes. Small shape change implies that the connectivity between parts in the design space are not updated iteratively.