NASA Langley Res. Ctr., MS 463, Hampton, VA 23681-0001
Analytical Services and Mater., Inc., Hampton, VA 23369
Northwestern Univ., Evanston, IL 60201
The response of an acoustically excited flexible surface together with the resulting sound radiation was considered. A model was employed that accounts for the full coupling between the surrounding fluid and the vibrating surface in three dimensions as well as two dimensions. The model couples the nonlinear Euler equations with an equation describing the nonlinear vibration of the plate. Different regimes of plate vibration and acoustic radiation were described, including linear, nonlinear, quasiperiodic, and apparently chaotic dynamics. It was found that, in the linear regime, the effect of the fluid/structure coupling is not significant. In the nonlinear regime, the effect of the coupling is to significantly reduce the harmonic content in both the plate vibration and the acoustic field. Furthermore, the nonlinear radiation exhibits a relative increase in harmonic content and an overall reduction in level as the acoustic propagation distance increases.