Influences of Angular Position of Unbalanced Force on Crack Breathing Mechanism

摘要

In this study, a new mathematical model is developed to study crack breathing behaviours considering effect of angular position of unbalanced force at different crack locations. Crack breathing behaviours are determined by using effectual bending angle and studying the transient change of the crack area. Different crack breathing behaviours of the unbalanced shaft are observed for different combinations of angular position of unbalanced force with crack location, except for two crack locations at 0.3 L and 0.8335 L, in which L is the total length of the shaft, where unbalanced shaft behaves completely like a balanced shaft. Based on different combinations of angular position of unbalanced force with crack location, the stiffness of unbalanced shaft varies accordingly. An unbalanced shaft is stiffer than a balanced shaft when angular position of unbalance force is between 90° to 270° and crack located between 0.3 L and 0.8335 L and it is flexible when the crack is located outside of this crack region. On the other hand, it is flexible when angular position of unbalanced force is between 0° and 90° or 270° to 360° and the crack is located in the middle region and it is stiffer when the crack is located outside of this crack region.