Abstract:

Topology optimization is a commonly used method to determine the optimal design of damping material layout in train, automotive, and aerospace products. In this study, a coupled system of a flexible face with closed acoustic cavity is established. A unit load is applied to the flexible face, and the response sensitivity and modal participation factor of the filed point are analyzed. Three response sensitivity peaks are found at the low-frequency band (20-180Hz), and the corresponding main modal participation factors are the first, fourth, and eighth orders. The three peaks are reduced by damping treatment. A method for objectively calculating the modal weight of each order using three response sensitivity peaks is proposed. The comprehensive modal loss factor of the mode corresponding to the three peaks is targeted, the position of the damping material is the design variable, and the amount of damping material is the constraint. The evolutionary structural optimisation (ESO) method is used to design the layout of damping materials. Aiming at the checkerboard problem in the optimization process, the calculation sensitivity is filtered to stabilize the optimization. Results show that the response sensitivity of the third peak in 173Hz is reduced by 33.2 and 26.5 dB(A) under free damping and constrained damping treatments, respectively. The two other response sensitivity peaks are also remarkably decreased.

Key words: acoustic-structural systems, ESO method, weighting factor, response sensitivity