基于简单缺口件等效的发动机关键零件疲劳极限预测方法研究

疲劳极限是动载下机械零件的重要物理量，表现为机械零件对周期应力的承受能力。本项目开展机械零件疲劳极限预测方法的研究，构建交变应力场与疲劳源产生进而形成微裂纹的对应关系，提出疲劳极限预测等效理论，揭示零件与缺口试件的等效机理，寻求零件与缺口试件的应力集中处应力场拟合及等效方法，完善疲劳极限预测等效理论，并以发动机关键零部件机体、曲轴和连杆为例，试验验证准确性。项目提出疲劳极限预测等效理论，将复杂零件疲劳极限求解问题转化为简单缺口件疲劳极限求解问题，解决现有直接估算复杂零件疲劳极限的局限，为复杂零件疲劳极限预测提供一种新思路。

As an important phsical parameter of mechanical parts in dyanmic loading, fatigue limit refers to parts' capacity to cycle stress. This research project focuses on the prediction methods of parts' fatigue limit, planning to find out the correspondence between alternative stress field and emergence of fatigue source as well as the microcracks formed. Based on the research, researchers are able to put forward equivalence theory of fatigue limit prediction, reveal the equivalence mechanism between parts and notch specimen, and consequently seek the stress field fitting and equivalence methods between parts and the stress concentration spot of notch specimen. The accuracy of the research will be further tested with the block, crankshaft and connecting rod of core engine parts. With an equivalence theory proposed on fatigue limit prediction, the research could tranfer the complex problems of parts fatigue limit solution into simple problems of notch fatigue limit solution and breach the current limitation on direct estimation of complex parts' fatigue limit, providing a new line of thinking in this field.