裂纹倾斜角度对呼吸裂纹转子非线性刚度及动力学特性的影响

The stiffness matrix of inclined crack elements was established based on the stress intensity factor, and time-varying characteristics of cracked rotors stiffness during a steady rotation period were compared under different crack inclination angles. Due to the dynamic model of cracked rotors, dynamic response of inclined cracked rotors was simulated. Results show that rotor systems with inclined cracks exhibit strong nonlinear characteristics. What’s more, coupling stiffness in the bending direction of rotor systems with inclined cracks is significantly greater than that of the rotor systems with transverse cracks. Under the influence of nonlinear change of stiffness of cracked rotors, the vibration amplitude of cracked rotors in bending direction in fundamental frequency, 2 times frequency and 3 times frequency rises with the increase of crack inclination angle. In contrast, the vibration amplitude of 5 times frequency decreases with the increase of the crack inclination angle. With the change of crack inclination angle, the vibration amplitude of fundamental frequency changes about 1%, the vibration amplitude of 2 times frequency changes about 20%, the vibration amplitude of 3 times frequency changes about 4.7%, and the vibration amplitude of 5 times frequency changes about 25%.