Finite Element Airplane Cost Analysis

A finite element structural analysis was extended to calculate the dollar cost of the structure and then linked to an “optimizer” to minimize the cost.

This paper describes the initial effort to develop a computer program which will analyze a given structure under a known loading envolope and then optimize the member sizes to give a minimum total cost. The output from a structural analysis program forms the input for a linear optimization program. Since the optimizer was linear, and the problem in this case was nonlinear, the program was written using an iteration loop around the three FORTRAN subroutines, STRUCT, CONVRT, and SMPLEX. Iterations stop when the change in two successive cost calculations is within a limit set by the engineer or when the number of iterations exceeds a preset limit. The method is applied to some simple examples, and results are compared with the work of other authors.