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为了对裂纹静子叶片在共振激励下的损伤容限寿命潜力进行初步探索,采用接触有限元法研究了共振状态下裂纹梁的振动与疲劳裂纹扩展的耦合问题。裂纹梁采用二维平面应力单元离散,接触模型模拟呼吸裂纹开合过程中的弯曲刚度变化。振动分析中,分别使用解析法预估和瞬态响应扫频计算得到系统一阶共振频率。断裂力学参量在有限元法中使用线弹性断裂力学方法进行求解。耦合分析中,模拟了耦合现象中的两个典型问题——裂纹止裂和失稳扩展,通过在共振激励下扫描裂纹长度计算应力强度因子曲线,通过该曲线与断裂韧度、裂纹扩展门槛值对比判断裂纹扩展的稳定性、计算裂纹扩展寿命。最后使用耦合分析结论基于Campbell图对假设静子叶片进行了定性的共振分析。
In order to explore the potential of damage tolerance life of cracked stator blade under resonance excitation, the contact finite element method was used to study the coupling of cracked beam vibration and fatigue crack growth under resonance condition. The crack beam is discretized by two-dimensional plane stress element, and the contact model simulates the change of bending stiffness during the opening and closing of respiratory crack. In the vibration analysis, the first-order resonance frequency of the system is calculated by using analytical method and transient response sweep respectively. The fracture mechanics parameters are solved by the method of linear elastic fracture mechanics in the finite element method. Coupling analysis simulates two typical problems in the coupled phenomena - crack arrest and instability propagation. The stress intensity factor curve is calculated by scanning the crack length under resonant excitation, and by the curve and the fracture toughness, the crack growth threshold Compare the stability of crack propagation and calculate the crack propagation life. Finally, the results of coupled analysis were used to conduct qualitative resonance analysis of hypothetical stator blades based on Campbell plots.