Case studies on structural-acoustic optimization of a finite beam

This paper presents a case study on structural-acoustic optimization. It demonstrates the potential of the application of normal modes in external acoustics for optimization of radiating structures. Herein, a radiating beam is investigated in half space (baffled beam) and in free space. Optimization is run for different cases of excitation and bearing conditions. The radiated sound power level is minimized in a frequency range of approximately eight modes of the structure. The frequency range under consideration starts above the lowest elastic mode. Density, thickness and Young's modulus account for the optimization variables. A number of interesting results are reported. Substantial improvements may be achieved in cases where the a point force is applied. In cases of distributed load, gains are much more moderate. Density and thickness seem to be well suited for these optimization purposes whereas the Young's modulus seems to influence the objective function much less. Essentially, the results of optimization appear very sensitive with respect modification of the load's location but robust with respect to bearing conditions.