The effect of Crack-Friction Damping on the Vibration and Fatigue Crack Growth of Beams with Breathing Crack

• Main Authors: Chao-Tien Chang, 張肇殿
• Other Authors: Yan-Shin Shih
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/hcvbmp

碩士 === 中原大學 === 機械工程研究所 === 92 === ABSTRACT In this study, the beam of circular or square cross section subjected to a cyclic loading is considered as Euler’s beam.The straight-edge type of crack locates at the center of beam.The damping due to the friction of crack surface is considered in which the damping ratio or loss factor is simulated as the model provided by Sanliturk and Imregun. The equation of motion is derived by Hamilton’s principle, and the shape function is applied to satisfy the boundary conditions. The equation of motion is simplified to Mathieu equation by Galerkin’s method. For the crack, the breathing model of crack is used, and the stiffness corrected. In a cycle of vibration , the fourth order of Runge – Kutta method is applied to determine the amplitude of vibration, and The modified Forman model is applied to determine the rate fatigue crack growth. Both vibration and fatigue analyses are coupled cycle by cycle. The effects of crack-friction damping on the vibration and fatigue crack growth is determined and discussed in this study. The results can be concluded that the crack-friction damping does not influence at the excite frequency 0.1 ~0.2 ,.and does evidently influence at 0.5 ~ 2 . keywords:damping, fatique crack, loss factor, breathing crack, exciting frequency, amplitude,vibration.