RADIATED SOUND FROM A CLAMPED CIRCULAR PLATE EXCITED IN THREE DIRECTIONS

An experimental and theoretical study of the sound radiated from a centrally driven clamped circular plate was performed to gain information about the acoustic transfer function of this model. This was a phase of a study of parameters which influence the radiated sound due to a vibration source mounted inside a ship hull. The relative acoustic importance of vibrational force and torque inputs was investigated for three principle directions: normal to the plate, parallel to the plate, and rotationally flexing the plate. The experimental results indicated that contributions from motion in the plane of the plate were negligible. At low frequencies, the normal input direction was dominant, but the rotational input became more important at higher frequencies (above 1000 cps for this model). The theoretical treatment yielded the velocity distribution over the plate for the modes excited by a normal drive and the near and distant radiated sound fields. The solutions were integrated numerically for points on the axis of the plate. The ratio of the axial far-field to near-field radiated sound was computed to permit deducing the far-field acoustic transfer function from near-field data. (Author)