中文摘要：

纵振换能器与薄圆盘组成的复合系统在实际中有诸多应用。笔者利用有限元法，研究了不同激励面积的纵振换能器激励薄圆盘中心，该激励源频率与圆盘弯曲振动基频相等时，在产生的弯振模式中，激励源面积大小对该圆盘节圆位置的影响。结果表明：激励源面积保持不变时，频率越高的弯振模式，节圆半径越大；对同一纵振激励源面积，振动系统有多个振动模式，纵振激励源面积在一定大小范围内，该振动系统存在一个与纵振换能器频率相近的纵弯共振模式。在纵弯共振模式下，随着激励源面积的增大，节圆半径减小，最终消失，进一步计算发现该节圆的消失与激励源面积和圆盘面积的比值有关。实验与理论计算基本吻合。

英文摘要：

The integrated system of longitudinal transducer and thin circular plate has a wide range of applications. In this paper, by using finite element method, when a longitudinal transducer with different areas excites the center of a thin circular plate whose fundamental flexural frequency is the same as the transducer, the effect of different exciting area of the longitudinal transducer on the location of nodal circle of the plate in its flexural mode is ana- lyzed. The results show that when the area of excitation remain unchanged, the higher the frequency of the flexural vibration mode, the greater the radius of the nodal circle. One exciting area of longitudinal transducer can produce many different vibration modes, in which there is one resonant mode of longitudinal-flexural vibration whose frequency is close to the frequency of the longitudinal transducer when the scope of the exciting area is in a certain range. In the resonant mode of longitudinal-flexural vibration, as the area of excitation increase, the radius of nodal circle decreases and finally vanishes. Further study shows that the disappearance of nodal circle is related to the ratio of exciting area and plate area. The experimental results agree well with those of theoretical calculations.