转子系统常开裂纹故障信息提取方法的研究

Research on Fault Diagnosis Information of Open Crack for Rotor System

针对由于横向常开裂纹引起的裂纹故障转子系统,根据Paris理论,运用由应力强度因子及应变能密度函数推导得到的裂纹柔度系数矩阵,建立了裂纹转子系统动力学模型.由于含有横向裂纹故障的转子系统的刚度矩阵会发生相应变化,因此,在已知柔度系数矩阵的基础上,通过对比无故障转子系统与裂纹转子系统的动力学方程,可以推导出裂纹转子系统的剩余量动力学方程.分析裂纹所在轴段两端的受力情况,结合剩余量动力学方程,从振动信号中提取出常开裂纹发生的位置及裂纹深度信息.结果表明,本文运用的常开裂纹信息提取方法理论上只需要采集两个不同转速下,三个节点的振动信号进行诊断分析,简便可行,并可为转子系统、悬臂梁、桁架结构等常开裂纹故障诊断提供一定的理论依据.

According to the rotor system with crack fault caused by transverse open crack,the dynamic model of crack rotor system was established using the crack compliance coefficient matrix that is derived from the stress intensity factors and strain energy density function based on the Paris theory.Since the stiffness matrix of rotor system with transverse crack fault will have corresponding changes,the surplus dynamics equation of cracked rotor system can be deduced by comparing the dynamics equations of the fault-free rotor system with that of the crack rotor system based on the flexibility coefficient matrix.Moreover,the information of open crack’s location and depth can be extracted from the vibration signal by analyzing stress condition at both ends of the shaft segment where crack exists and combining with the surplus dynamics equation.The results show that the open crack information extraction method used in this paper only needs to collect the vibration signal of three nodes at two different speeds to make diagnostic analysis.This method is simple and feasible,which may provide certain theoretical basis for the open crack fault diagnosis of the rotor system,cantilever beam and truss structure.