本文以有限元素法來分析連桿含裂縫之速回機構的動態行為。撓性連桿以Timoshenko樑來模擬，即考慮連桿的旋轉慣性以及剪應變效應；考慮曲柄為剛體，且以定轉速旋轉帶動撓性連桿。撓性連桿上的裂縫假設為開啟狀態的橫向裂縫，並利用裂縫之應力強度因子及卡氏定理推導出含裂縫元素的局部柔度矩陣。本文以有限元素法和Lagrange 方程式推導系統的運動方程式，並以Runge-Kutta數值積分方法求解系統的動態響應，探討當撓性連桿上的裂縫位置不同和裂縫深度不同時，對系統之動態響應的影響。數值結果顯示，裂縫位置越靠近平移旋轉套筒處，連桿端點位移之動態響應的振幅越大。另外裂縫的深度越大，系統動態響應的振幅也越大。

　Dynamic response of a quick-return mechanism with a crack in the flexible linkage is investigated in this thesis. The flexible linkage of the system is modeled as a Timoshenko beam, which includes the effects of rotary inertia and shear deformation. The rigid crank drives the flexible linkage at a constant angular speed. The crack in the flexible linkage is modeled as a transverse open crack whose local flexibilities are calculated by using a fracture mechanics approach and the Castigliano’s theorem. The finite element method and Lagrange equation are employed to derive the equations of motion of the system. Dynamic responses are obtained by using the Runge-Kutta method. Influences on dynamic response of the system due to different depths and locations of the crack on flexible linkage are investigated.

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