纵波回形变幅杆的研究

Study on Longitudinal Vibration of a Folded Acoustic Horn

由于在回形变幅杆中,纵向振动通过中间圆盘耦合,传统纵振变幅杆的设计方法已经不能完全适用,根据回形变幅杆的结构特点和振动传播特性,分析了纵波在变幅杆圆盘中发生的模态形式变化。在圆盘部位振动以切向振动模态为主,类似于柱面波径向传插,耦合后又转换为纵波形式输出。基于波动方程建立了回形变幅杆的频率方程,并讨论了利用频率方程结合有限元进行变幅杆结构尺寸的设计方法。试验结果表明,回形变幅杆的频率和变幅比与理论计算结果基本一致,且机械阻抗较小。

Since longitudinal vibration is coupled with the middle disk in a folded acoustic horn,the conventional design method of longitudinal acoustic horn is no longer applicable to it.According to the structure characteristics and the vibration propagating feature of the folded acoustic horn,the change of modal forms of longitudinal wave in the folded acoustic horn was analyzed.The vibration model of the disk is mainly the tangential vibration which is similar to the cylindrical radial wave propagation.It converts to longitudinal wave after coupling.Based on the wave equation,the frequency equation of the folded acoustic horn was built and a method for designing the horn dimension was presented using the frequency equation and finite element analysis.The experimental result shows that the horn frequency and amplitude ratio are basically consistent with the theoretical calculation result,and the mechanical impedance is small.