Analysis of Sound Pressure Radiated from Vibrating Beam

This investigation is the fundamental study to clear the mechanism of sound radiation from a machine structure and an architecture. In this paper, the sound radiation of an unbaffled beam of rectangular cross section is cleared. The relation between the amplitude of velocity and the sound pressure of an unbaffled beam is theoretically analyzed in consideration of the following cases. 1) The plane wave is radiated from a vibrating beam. 2) The mechanism of sound radiation from a vibrating beam is equivalent to that from two spherical sound sources. The analytic results are verified by experiments. It is concluded that in these experimental results, the sound pressure of an unbaffled beam is influenced by the amplitude of velocity, excitation frequency, the dimension of rectangular cross section of beam, and the distance from origin to observation point. In the latter, an agreement between the experimental results and the numerical results is obtained, but it is not so in the former.