CONSERVATIVE METHODS FOR STRUCTURAL OPTIMIZATION

Several methods can be used to generate conservative designs when using structural optimization techniques. A method is introduced which adds a padding term to each constraint that is proportional to the gradient of the constraint. One way to implement this approach is to determine the gradients of the constraints at the unpadded optimum design, to modify the constraint allowables, and then to restart the optimization. This approach assumes that these gradients will not change significantly when the new optimum is located. A second implementation is proposed which imbeds the padding calculation into the optimization process by updating the padding term periodically during the optimization process. Numerical experiments indicated that the additional nonlinearity introduced by this method did not affect the solution progress. Finally an implementation which uses nonlinear constraint approximations and a second order update method is described. It was shown that all implementations produced more mass efficient designs than does the more traditional method of adding a constant safety factor to each constraint. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.