Wind turbine (WT) gearbox bearings experience premature failures. Damage characterisation of failed bearings has shown that subsurface micro cracks and butterfly-wing cracks are associated with non-metallic inclusions in the bearing raceways. The existing studies are unable to predict crack propagation under rolling contact fatigue considering shakedown and ratchetting when the material around an inclusion experiences sufficiently high levels of stresses. In this study, a finite element (FE) damage model based on the Continuum Damage Mechanics (CDM) is developed, integrated with the modelling of plastic deformation and kinematic hardening when the material around inclusion is subjected to alternating tension and compression. Two damage types of manganese-sulphide inclusions are investigated, showing significant effects of inclusion boundary separation and internal cracking on the subsurface RCF crack evolution. The modelling results also show that higher surface traction, overloads and varied loading sequences, commonly experienced by WTs in operation, have significant effects on the increase of the subsurface butterfly-wing crack lengths, because of early crack initiation and accelerated crack propagation. The developed CDM FE model has shown its effectiveness in predicting the damage evolution to gain new insights of complex interactions of a number of critical factors that can lead to the premature failure of bearings.

中文翻译：

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预测滚动接触疲劳下表面下夹杂物引发的蝶翼裂纹


风力涡轮机 (WT) 齿轮箱轴承会过早失效。失效轴承的损伤特征表明，表面下微裂纹和蝶翼裂纹与轴承滚道中的非金属夹杂物有关。当夹杂物周围的材料承受足够高的应力时，考虑到安定和棘轮作用，现有研究无法预测滚动接触疲劳下的裂纹扩展。在本研究中，开发了一种基于连续损伤力学 (CDM) 的有限元 (FE) 损伤模型，该模型与夹杂物周围的材料受到交替拉伸和压缩时的塑性变形和运动硬化建模相结合。研究了硫化锰夹杂物的两种损伤类型，显示了夹杂物边界分离和内部裂纹对次表面 RCF 裂纹演化的显着影响。模拟结果还表明，水轮机在运行中通常会经历较高的表面牵引力、过载和变化的加载顺序，由于早期裂纹萌生和加速裂纹扩展，对地下蝴蝶翼裂纹长度的增加有显着影响。开发的 CDM FE 模型已显示出其在预测损坏演变方面的有效性，以获得对可能导致轴承过早失效的许多关键因素的复杂相互作用的新见解。