BESO of Structures with Constrained Damping

Abstract

Optimization of structures with constrained layer damping by bi-directional evolutionary structural optimization???BESO???was studied in this paper. The sensitivity equation of the objective function about deleted and added elements was built for maximization of modal loss factor of constrained layer damping structure. Firstly the FEA model of the metal structure without constrained layer damping are built, and the mode shapes are calculated. Secondly substitute the mode shapes into the sensitivity formula, to calculate the sensitivity of the elements of the metal structure with supposed constrained damping. Thirdly sort to find the element with negative or minimum modulus sensitivity, and stick the material to where those elements are to initialize the optimization configuration. BESO then was import into the optimization base on the initial optimization configuration. If a pair of deleted and added elements increase the certain stage modal damping ratio, the pair then should be implemented until no such pairs, then the optimal layout of the constrained layer damping materials we get. The mass added should be equal to the deleted to assure the mass of the constrained layer damping material. The example shows that BESO can get the optimal layout of the given mass of damping materials to maximize the certain stage loss factor and save 90% time compared to ESO. The reasonable result demonstrates the effectiveness and engineering value of the method.