Analysis and Experimental Measurements on Dynamic Characteristics of Giant Magnetostrictive Material, Layered Piezoelectric/Piezomagnetic Composite Material and Moving Coil Loudspeaker
Date Issued
2014
Date
2014
Author(s)
Chao, Chun-Yu
Abstract
The out-of-plane dynamic characteristics of giant magnetostrictive material (GMM) and moving-coil loudspeaker ,and the three-dimensional dynamic characteristics of layered piezoelectric/piezomagnetic composite material are studied and discussed in this article. The result of out-of-plane dynamic characteristics of giant magnetostrictive material is obtained by experiment measurements and theoretical analysis. The investigation of GMM is provided by using the various excition methods. In order to study the out-of-plane and the in-plane vibrating characteristics of layered piezoelectric/piezomagnetic composite material composed of GMM and piezoceramic rectangular plate, both the results for experimental measurement and theoretical calculation are provided and compared. Finally, we use various experiment techniques to analyze the influence of different material properties of diaphragms on the out-of-plane dynamic response and sound pressure level (SPL) curve. The correlation and the coupling of mechanical vibration and acoustic field are investigated.
Several experimental methods are used to measure the dynamic characteristics of GMM, layered piezoelectric/piezomagnetic composite material and moving-coil loudspeaker. First, the full-field optical technique, amplitude-fluctuationion electronic speckle pattern interferometry (AF-ESPI), is used to measure simultaneously the resonant frequencies and mode shapes for out-of-plane and in-plane vibration. The excited voltages for different mode shapes is referred to the efficiency of resonant vibration. Second, the point-wise measurement system, laser Doppler vibrometer (LDV), is used to obtain the out-of-plane resonant frequency. Third, the correspondent in-plane resonant frequencies and anti-resonant frequencies are obtained by impedance analysis, and the electromechanical coupling coefficients can be calculated from impedance spectrum to perform the efficiency of resonance mode. Infrared thermography is also full-field optical technique to measure the distribution of temperature field. The results of the experimental measurement of the GMM and the layered piezoelectric/piezomagnetic composite material are compared with the theoretical result. The resonant frequency and mode shape obtained from two methods have good agreement. The vibrating characteristics of moving-coil loudspeakers have good correlation for AF-ESPI and SPL curve.
Subjects
超磁致伸縮材料
層狀壓電壓磁複合材料
動圈式揚聲器
共振頻率
振動模態
電子斑點干涉術
雷射都卜勒振動儀
阻抗分析儀
音壓位準曲線
紅外線熱像儀
振動特性
Type
thesis
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