The free vibration response of a thin rectangular plate in contact with fluid is experimentally studied by Acoustic and Modal tests. To this purpose, a series of experiments are done on rectangular plates contacting fluid, with different dimensions and materials, wherein the plate is connected on one side of a heavy solid container by certain number of bolts, where are situated near to each other on the boundaries of the plate to make clamped support. In Acoustic test, the plate in contact with an inviscid fluid is stimulated by a hammer and the produced sound from free vibration of the plate is sampled by microphone. Thereafter by transforming of sound pressure signal to frequency domain, the natural frequencies of the plate are acquired in different spectrum. To verify the method, some Modal tests are performed and also an analysis is done via Rayleigh-Ritz method. Comparing results of experiments and theory shows good agreement between them. Finally by considering frequency response function, natural frequency of the plate is extracted in different height of the fluid and effects of some parameters on the natural frequencies such as fluid height and dimensions of the plate are studied.
