直斜裂纹转轴的时变刚度特性研究*

本文采用有限元方法建立了裂纹转子系统的动力学方程，利用应变能释放率方法得到了裂纹单元的刚度矩阵，采用应力强度因子为零法模拟裂纹的呼吸效应，详细研究了不同深度的直裂纹和45°斜裂纹转子，在一个稳态旋转周期内，裂纹开闭规律以及转轴刚度时变特性。研究表明裂纹深度的增大使裂纹转轴的刚度变化增大，直裂纹与斜裂纹转轴的刚度变化特性具有明显差异，斜裂纹引起更多与更强的耦合振动，使转子的动力学性能更复杂。

Time-varying stiffness characteristics of rotating shaft with transverse and slant crack

The dynamic equations of the cracked rotor system were established using finite element method. Based on the approach of strain energy release rate, the stiffness matrix of the crack element was derived. The breathing behavior of the crack was represented by taking into account the opening and closing of the crack using stress intensity factor. The detailed researches were done on the characteristics of the breathing rules of transverse and slant cracks and the time-varying stiffness of the cracked element in a steady rotating period. The increase on the surface crack depth raises the variation of the stiffness of the cracked shaft. The characteristics of stiffness variation of the shaft with transverse or slant crack are not the same. Compared with the transverse crack, the slant crack will lead to more and greater coupled vibration. And the dynamic performance of the rotor will be more complicated.