38. Sound Transmission of Beam-Stiffened Thick Plates

Beam-stiffened thick plates are the fundamental components of many large engineering structures such as power transformers, ships, and offshore platforms. Vibration and sound transmission properties of beam-stiffened plates due to an external sound pressure excitation on one side of the plate will determine the sound field characteristics on the receiving side of the plate. This paper presents an analytical study on the vibration response and sound transmission of a beam-stiffened thick plate under the excitation of an acoustic plane wave. The sound radiation of the stiffened plates due to the sound excitation and that due to a mechanical excitation force applied on the plate are also compared in the study. It is found that in the mechanical excitation case, the normal quadratic velocity and radiated sound power increase gradually with an increasing frequency, while it is vice versa in the sound excitation case. It is also shown that the averaged sound radiation efficiency of the plate due to sound wave excitation on the plate is generally higher than that due to the mechanical excitation before the critical frequency and vice versa after the critical frequency. Effects of beam insertion on sound transmission of the plate are also investigated in the study. Results obtained from this study can be used to guide the noise and vibration design of power transformer tanks and machine covers.