Janus-Helmholtz换能器与Janus-Hammer Bell换能器的振动模态研究

Study on vibration modes of Janus-Helmholtz transducer and Janus-Hammer Bell transducer

Janus-Helmholtz(JH)换能器和Janus-Hammer Bell(JHB)换能器外观结构类似,但两者振动模态不同。为明确二者振动模态的不同,分析了其结构参数对振动模态的影响。结果表明:在其他参数确定的条件下,JH换能器中圆环壳轴向长度L与圆环壳内侧半径a的关系应满足2<L/a<5.7,JHB换能器对应圆环壳长径比L/a的取值范围为0.1<L/a<0.3。利用有限元方法并设置特殊边界条件分析了JH换能器与JHB换能器谐振峰对应的振动模态,发现JH换能器中较低频振动模态为Janus纵振模态,高频振动模态为液腔谐振模态;JHB换能器中较低频振动模态为Janus纵振模态,较高频振动模态为圆环呼吸模态。进一步对比了JH换能器和JHB换能器的径向与轴向发送电压响应,发现JH换能器可以实现更宽的工作带宽和更高的发送电压响应;JHB换能器工作带宽较窄,但径向方向发射电压响应起伏较小。

Janus-Helmholtz(JH)transducers and Janus-Hammer Bell(JHB)transducers have similar appearance and structure,but their vibration modes are different.This article firstly analyzes the structural parameters corresponding to different vibration modes in JH transducer and JHB transducer.Under the conditions determined by other parameters,through theoretical calculation,it is concluded that the relationship between the axial length L of the ring shell in the JH transducer and the inner radius a of the ring shell should satisfy 2<L/a<5.7.The value range corresponding JHB transducer is 0.1<L/a<0.3.Then the finite element special boundary condition setting method is used to analyze the vibration modes corresponding to the resonance peaks of the JH transducer and the JHB transducer.It is concluded that the lower-frequency vibration mode in the JH transducer is the Janus longitudinal vibration,and the high-frequency vibration mode is the cavity resonance mode.The lower-frequency vibration mode in the JHB transducer is the Janus longitudinal resonance,and the higher-frequency vibration mode is the ring breathing mode.Finally,the radial and axial transmitting voltage responses of the JH transducer and the JHB transducer are compared to analyze work performance under different working modes,and it is concluded that the JH transducer can achieve a wider operating bandwidth and a higher transmitting voltage response.The working bandwidth of JHB transducer is narrow,but the transmitting voltage response in the radial direction has small fluctuations,and the transmitting voltage response in the axial direction has large fluctuations.