The Radiation Resistance of a Baffled Rectangular Panel

Abstract

The radiation resistance of a panel, vibrating in a single mode, is theoretically determined from the acoustic power radiated. The panel is supported in an infinite baffle. The supports include hinges on all four sides and either hinged or clamped supports on two opposite sides with the other sides unsupported. Asymptotic solutions are found and curves covering the entire frequency range are obtained through numerical integration. Well below the critical frequency, the radiation resistance of a panel hinged on all four sides is a minimum for square intranodal areas. By considering a panel or beam either hinged or clamped at each end and vibrating at a given frequency well below the critical frequency, it is found that the ratio of the radiation resistance of the clamped beam to that of the hinged beam is 0.851 for the first mode and 0.711 for the second mode, and approaches 2 as the mode number tends to infinity. For both hinged and clamped supports, the radiation resistance of all modes increases with the beam width-to-length ratio. [Supported by the National Research Council and the NASA Langley Research Center.]