Sensitivity Analysis And Optimization Design Based On The Complex Variable Semi-analytical Method

The competition in the field of machine manufacturing is increased quickly. The design of the products depend on the structure optimization design. In the optimization of gradient method, the accuracy of the sensitivity determines the direction of the optimization search and the accuracy of the optimization results. As common methods, the global finite difference method and the semi-analytical method have inaccuracy problem for shape design sensitivities which need to eliminate errors by correction factors.This paper analyzes the theory of the complex variable semi-analytical method and then come to a conclusion that this method can be used to calculate many structural sensitivities.Truss structure plate structure and shell structure are analysed by finite element method.Writing the truss and shell finite element analysis calculating programs which contain of this new artithmetic are written. Comparing the efficiency with the global finite element method and the semi-analytical method. Studies on the three dimensional structure analysis. Writing eight nodes and hexahedron elements sensitivity analysis program and then do the sensitivity analysis to the thick wall pipe and the tee. At last, in order to test the effect, this approach is used to determine material properties and to optimize the structure of plane truss.The result of the study shows that the complex variable semi-analytical method always can get accurate sensitivities in different kind of elements. The accurate sensitivities are independent on the length of the difference step and as efficiently as the semi-analytical method. this paper expand the reach of the new method to apply to the 3D structural. Iteration times can be further reduced in the design optimization of gradient by this new algorithm. The optimization results are also improved.