Vibration Analysis of Liquid Coupled Circular Piezoelectric Laminates

• Main Authors: En-Chih Teng, 鄧恩智
• Other Authors: Ching-Chung Yin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/75761829859577988817

碩士 === 國立交通大學 === 工學院碩士在職專班精密與自動化工程組 === 96 === A coordinated experimental and numerical investigation of vibration characteristics of liquid coupled circular piezoelectric laminates is presented in this thesis. The circular piezoelectric buzzers clamped at their borders in horizontal and vertical set-ups, respectively, are loaded by liquid on one side. Resonant frequencies of the buzzer immersed in liquid are usually reduced to lower values than those measured in its free state. The contributions due to both adding mass of liquid and structural damping are verified through experiments and simulation carried out by ANSYS commercial code. Resonant frequencies and their corresponding natural modes of the buzzer which is free of damping were determined first by ANSYS. Numerical result reveals that the difference between resonant frequencies of free buzzer and the one immersed in water tends to monotonically decrease with the increase of liquid level in either vertical or horizontal set-up. The addition of liquid to the buzzer has significant influence on the drifts of resonant frequencies. The variation becomes a constant if liquid layer approaches a limited thickness. Resonant frequencies were measured by use of a SigLab spectrum analyzer in experiments. The measured values have the same trends as numerical results. Based on hypothesis of proportional damping, the damping factors related to mass and stiffness are determined through measurement. The influence of structural damping is much less than adding mass in simulation by ANSIS. The contribution of structural damping can be ignored in most cases. The simulated resonant frequencies are lower than measured ones. The agreement can be remedied if hydrostatic pressure-induced radial pre-stress is included in calculating resonant frequency values of the buzzer.