Sound radiation by a simply supported unbaffled plate

Sound radiation by a simply supported unbaffled plate is presented using a double layer integral representation of the acoustic pressure. Both the pressure jump and the plate displacement are developed in series of the simply supported plate modes. This leads to modal coupling coefficients, which are numerically calculated for this specific unbaffled problem. The unbaffled problem is then transformed in the presentation of the baffled one which allows us to define original modal radiation impedance coefficients to the unbaffled plate. Baffled and unbaffled radiation impedances are then compared versus nondimensional frequency, in real and imaginary parts for a set of representative modes. An approximate expression for the direct unbaffled radiation impedance is presented, which is useful for light fluid loading. Finally, the influence of the baffle on sound radiation both in light and in heavy fluid, on the acoustic radiated power, the plate velocity, and the radiation factor is investigated.