Dynamic Analysis and Vibration Suppression of Elastic Structures Possessing Rocking Modes

• Main Authors: Chen, Sin-Yan, 陳信諺
• Other Authors: Lin, Yih-Hwang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/42347563614294858332

碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 104 === This study deals with rocking mode vibration suppression of micro-speakers due to the assembly defects from the production process, poor quality of materials, or the other factors. Because micro-speakers are very small in size, piezoelectric materials will be used to tackle this problem. First of all, by referring to a simulation example of a piezo-fan from the finite element analysis software ANSYS, the inverse piezoelectric effect of the piezoelectric material is utilized to provide the excitation voltage to deform and drive the blade. The same operation principle is applied in this study, but the use of the piezoelectric effect is to suppress the structure vibration. To investigate whether this method can effectively suppress the vibration of structures, it is applied to suppress bending mode vibration of a simply supported beam and it shows that this technique is feasible for vibration suppression. The approach is further introduced to deal with the rocking mode vibration problems of micro-speakers. The micro-speaker cone’s rocking mode, being an out of phase vibration mode, must be treated by properly setting the positive and negative polarities of the piezoelectric material. As can be seen from the deformation of the cone in this analysis, the vibration suppression performance is superior by using the proposed strategy in this study, the higher the voltage, the better the vibration suppression. The micro-speaker’s rocking modes possess out of phase vibration characteristics, similar to the acoustic dipole source. This study further explores the dipole source phenomenon by using the finite element analysis software ANSYS and Wolfram Mathematica. Experimental observation is conducted as well to investigate the natural of the dipole source to enhance the understanding of the sound and vibration characteristics for structures possessing out of phase motion.