A Generalized Algorithm for the Study of Bilinear Vibrations of Cracked Structures

• Main Authors: Tzuo-Liang Luo, 羅佐良
• Other Authors: James Shih-Shyn Wu
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/94279429272720414077

博士 === 國立中興大學 === 機械工程學系 === 94 === Numerical and experimental investigations provide a link to the location and size of cracks caused by natural vibrations. Cracks may generally result in the variation of structural stiffness and hence enable structures to vibrate nonlinearly. In order to understand the vibrational behavior of crack structures accurately, the study proposes a general and efficient algorithm based on the finite element assumptions and the bilinear vibrational theory. All formulae are derived from the time domain properly and may apply to the overall non-linear motion cycle completely. The contact effect is also considered by introducing the degree of penetration on the cracked surface. By assessing the variation of natural frequencies in crack open and closed modes, changes in the dynamic characteristics of cracked structures are investigated. A single beam and a spatial rotor blade structure are used to demonstrate the validity of the current method. Results in estimation with the variation of vibrational behaviors are significant compared with those available from experiments as well as some other numerical algorithms. Conseuqently, it is obviously found that the current algorithm allows the prediction of the location and the magnitude of cracks more efficient and significant than before. Further extension of the current method to other related fields is highly suggested.