Optimization of the frequency averaged input power into plates with dynamic vibration absorbers using the Wave Based Method

When it comes to the vibro-acoustic analysis of panels there is a strong interest in reducing the radiated sound power which can be effectively decreased by minimizing the power injected into the plate. In this paper, a thin plate with Dynamic Vibration Absorbers (DVA) attached to it, is considered and optimized in order to reduce the average input power injected. Instead of classic numerical quadrature schemes, the residue theorem is used to evaluate the average input power over a frequency band. This results into a considerable reduction of computational efforts, as it requires only few function evaluations at complex frequencies, regardless of the bandwidth considered. Properties and location of the DVAs are chosen as design variables to minimize the average power injected into the plate by using genetic algorithms. The dynamic system behaviour is simulated by using the Wave Based Method (WBM). Next to an increased convergence rate as compared to classical element based techniques, the WBM is also free in determining the optimal position of the DVAs unlike the element based approaches, which restrict the optimum position to nodal grid locations. Moreover, when point connections are taken into account, only a small part of the WB system matrices needs to be recomputed at each iteration, resulting in a strong reduction of the computational effort. Numerical examples illustrate the benefits and the efficiency of the proposed optimization strategy.status: publishe