拉杆疲劳裂纹导致的组合转子性能退化研究

Research on performance degradation of combined rotor considering the fatigue crack in the rod

组合转子作为燃气轮机等的核心部件,其性能退化机理并不明确,揭示其性能退化机理并有效地进行性能退化评估对燃气轮机等长期安全运行具有重要意义.为此,从结构损伤导致性能退化的角度出发,分析拉杆裂纹引起的组合转子性能退化特性.分别建立了组合转子有限元模型和弯曲、扭转刚度模型,利用有限元模型对拉杆上含初始裂纹的组合转子进行裂纹扩展分析,得到拉杆裂纹扩展速率;利用弯曲和扭转刚度模型分析了不同深度的裂纹对组合转子振动的影响,得到组合转子固有频率随裂纹尺寸的变化规律;并提出了衡量由微裂纹导致的组合转子性能退化的度量指标,实现了拉杆裂纹引起的组合转子性能退化的定量评估.研究表明:随着拉杆裂纹尺寸的增大,裂纹的扩展速率变快;拉杆裂纹的存在对组合转子的弯振影响较大,对扭振影响相对较小.

Revealing the mechanism of performance degradation and assessing the degradation de-gree of a combined rotor ,one of the main parts in engine ,are important to maintain the engine for long-term safety operation .Performance degradation characteristics of combined rotor were discussed ,from the perspective view of performance degradation caused by rod crack .Finite ele-ment model ,bending stiffness model and torsion stiffness model of the combined rotor were es-tablished .The crack extension rate of the rod was gotten by using the finite element model .Al-so ,the influence of different depth of crack to the vibration on combined rotor was analyzed using the bending and torsion stiffness model to obtain the relations between natural frequency and crack size .Then ,the measurement of performance degradation which was caused by micro cracks was put forward ,and the assessment of performance degradation was completed as well .The re-sults showed that the micro crack extension rate got faster when the size of crack increased and the rod crack made much effect on the bending vibration of the combined rotor comparing with the torsional vibration .