Effect of large Amplitude Vibration on Fatigue Crack Growth for Simply-Supported Beam with Surface Crack

• Main Authors: Tzu-Yang Lee, 李子揚
• Other Authors: Yan-Shin Shih
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/w9w8vw

碩士 === 中原大學 === 機械工程研究所 === 103 === In this study, the large amplitude free vibration of a simply supported beam with a straight-edge crack at mid-span is considered. The equation of motion and boundary conditions are derived by Hamilton''s principle. The stiffness with opening crack is derived by fracture mechanics. The Mathieu equation and the stiffness of the beam without a crack are derived by Galerkin''s method. And then using Runge-Kutta method to determine the relationship between amplitude and time. About the crack model, both of the opening crack and the breathing crack are considered. And the different way to calculate the stiffness of the opening and breathing crack is provided. In addition, under the premise of large amplitude vibration, with the crack depth ratio in change, the relationship of frequency ratio and crack depth ratio with the opening crack and the breathing crack are discussed in this study. Modified Forman equation is used to calculate the relation of crack growth and loading cycles. Vibration on the crack, and crack growth related vibrations have also been described and discussed.