Evaluation of vibration-based method for structural nondestructive inspection

• Main Authors: Wen-Chang Tsao, 曹文昌
• Other Authors: Bor-Tsuen Wang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/37678698179202600302

碩士 === 國立屏東科技大學 === 機械工程系 === 90 === This work presents the evaluation of vibration-based method for structural nondestructive inspection. The finite element analysis (FEA) and the experimental modal analysis (EMA) are applied to a defected free-free plate for structural nondestructive inspection. Three faults defection program are developed to find the defected location based on the change of the mode shape difference method, the slope of mode shape difference method and the strain energy method. First, the structural model verification of both defected and undefected free-free plate is performed. The system modal parameters, including natural frequencies, mode shapes and frequency response function (FRF) can theoretically be determined by FEA. The conventional EMA is also carried out with the use of the impact hammer and accelerometer to obtain FRF as well as the modal paramaters. Both the FEA and EMA results as well as the theoretical solution from the literature are compared and verified. The modal parameters agree reasonably well. Numerical analysis to predict the defected(crack) location is also shown for the case of different crack depth, different crack locations, two cracks and skew cracks. The three faults defection program can reasonably predict the defected area for all cases. This work enhances the vibration-based method for fault diagnosis by utilizing the structural mode shapes.