Effects of excitation area of longitudinal transducer on the flexural vibration characteristics of a rectangular plate in stripe mode

• The nodal lines keep approximate straight if the excitation area is small.
• The nodal lines bend obviously if the excitation area is greater.
• The farther distance from excitation center, the greater deformation of nodal lines.
• Resonant frequency of rectangular plate increases with increase of excitation area.
• Deformed nodal lines may affect the highly directive sound radiated by plate.

The flexural vibration characteristics of a rectangular plate in stripe mode, driven at its center by a different longitudinal vibration ultrasonic transducer (LVUT) with different excitation area are investigated. The variation in the nodal lines and corresponding resonant frequency of the rectangular plate under different excitation area are calculated by using finite element method (FEM). The results show that the resonant frequency increases with the excitation area of the LVUT increasing, and the nodal lines bend obviously when the radius r of excitation area is greater than a certain value. The experimental tests are carried out by the aid of Polytec PSV-400 Scanning laser Vibrometer, and the results agree well those of numerically calculated. It indicates that the larger excitation area of longitudinal transducer may affect the ultrasonic field radiated by the rectangular plate.