基于裂纹单元法的转子系统裂纹动态扩展与动力学分析

Large-scale rotating machinery often operates in circumstances of high temperature, high pressure, and high loading and multiple disturbances, the propagation process of the initial crack is affected by the multi-source excitation and the dynamic responses of the rotor system, and in return the dynamics of the cracked rotor system are also influenced by the stiffness variation caused by the crack propagation. Thus the accurate analysis of crack propagation behavior and the dynamic characteristics of the rotor system are essential for the early detection of crack and remaining useful life (RUL) prediction. To explore the correlated influence of the dynamic crack propagation and dynamic characteristics, this project focuses on the modeling of crack propagation under multi-source excitation and nonlinear dynamics of the rotor system using the proposed cracked hexahedral element method, to study the coupling mechanism between the crack propagation behavior and the dynamic characteristics of the rotor system. The correlated influence of the dynamic propagation of the crack and the dynamics of the rotor system is further analyzed, to grasp the dynamic propagation rules and evolutionary features of the dynamic system. Finally, the experimental studies are carried out to validate the theoretical analysis. The implementation of this project will provide the theoretical basis for analyzing the crack failure of the rotor system, fault diagnosis and remaining useful life prediction, which are critical for enhancing the reliability and safety of rotating machinery in reality.

大型旋转机械转子系统往往在高温、高压、高负荷和多干扰环境下运行，产生初始裂纹后其扩展过程受多源激励载荷和转子系统动力学响应特性的影响，同时裂纹的扩展改变了局部刚度，反过来影响裂纹转子系统的动力学特性。为此，准确分析裂纹扩展行为和裂纹转子系统动力学特性对裂纹及早识别和剩余寿命预测至关重要。本项目旨在研究转子系统裂纹动态扩展与动力学特性的关联影响，基于裂纹单元法建立多源激励载荷影响下转子系统裂纹扩展模型和裂纹叶片-轮盘-转子系统非线性动力学模型，解析裂纹扩展行为与转子系统动力学特性的耦合机制，进而研究转子系统裂纹动态扩展过程与动力学特性的关联影响机理，掌握叶片裂纹和转子裂纹扩展规律和转子系统动力学演化特性，最后通过实验研究验证理论分析结果。本项目的实施将为裂纹转子系统失效过程分析、故障识别和剩余寿命预测提供理论基础，对提高转子系统可靠性以及保障旋转机械安全运行具有重要的理论和实际意义。

转子系统广泛应用于火箭发动机、航空发动机、燃气轮机等高端动力装备中，运行过程中转子系统往往承受高温、高压、高负荷和多干扰环境条件，转子系统的安全性与可靠性直接关系到装备的安全稳定运行。裂纹是转子系统中较难识别、危害巨大的故障型式，初始裂纹产生后，扩展过程受多源激励载荷和转子系统动力学响应特性的影响，同时裂纹的扩展改变了局部刚度，反过来影响裂纹转子系统的动力学特性。为此，准确分析裂纹扩展行为和裂纹转子系统动力学特性对裂纹及早识别和剩余寿命预测至关重要。本项目建立了考虑裂纹动态扩展过程的三维裂纹建模方法，形成了融入裂纹动态扩展过程的裂纹转子系统动力学特性分析方法。首先，通过引入裂纹单元法，基于三维裂纹的裂纹前端进行应力强度因子等断裂和裂纹扩展参数计算，获得裂纹动态扩展过程，然后通过更新裂纹的刚度矩阵，实现裂纹扩展过程与裂纹转子系统动力学特性的耦合分析。结合实际旋转机械转系结构，分析多转子之间、不平衡相位之间、不平衡量之间不同的组合关系对裂纹转子系统动力学特性的影响，通过研究获得了复杂轴系中裂纹转子系统的振动特征，为实际转子系统在线运行过程中的裂纹识别提供了理论依据。本项目的研究结果可为裂纹转子系统失效过程分析、故障识别和剩余寿命预测提供理论基础，对提高转子系统可靠性以及保障旋转机械安全运行具有重要的理论和实际意义。