Stiffness Influencing Factors Analysis of the Fully Opened Slant Crack Rotor

Based on material mechanics and fracture mechanics theory, the stiffness matrix of a shaft with slant transverse crack under the common action of axial force, moment and torque was derived by strain energy release rate method. The relationships between the stiffness and some parameters such as the crack inclination, the crack depth and the slenderness ratio are discussed in a static situation fully open crack. The studies have shown that, the stiffness of crack centerline and tangent crack was increased with the decrease of crack inclination when the crack is fully open in the static case. The change of crack shaft stiffness was increased with the decrease of crack depth. The stiffness of shaft has not been reduced, but has some breathing characteristics of fluctuations with increasing crack depth in the steady state crack axis of rotation cycle. Moreover, the coupled vibration was easily caused so that dynamic characteristic of shaft is more complex.