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为评估某航空星形活塞发动机主连杆结构强度,建立曲柄连杆机构运动学和动力学分析模型,得到主连杆载荷特性。建立了考虑结构接触非线性因素的主连杆应力计算有限元模型,通过由模拟装置得到的实测应力数据对模型进行了标定,进而计算得到整个工作循环内的动态应力场。结果表明:副连杆引起的附加弯矩是影响主连杆杆身危险部位应力过高的主导因素。在此基础上,考虑结构表面工艺状态等因素的影响,基于临界平面法对主连杆多轴疲劳强度进行了校核。结果表明:该连杆杆身与大头过渡区域处疲劳安全系数较低,计算危险点与实际疲劳裂纹位置一致。
In order to evaluate the structural strength of the main connecting rod of an aerospace radial piston engine, the kinematics and dynamics analysis model of the crank connecting rod mechanism was established and the main connecting rod load characteristics were obtained. The finite element model of stress calculation of main link considering the nonlinearity of structure contact was established. The model was calibrated by the measured stress data from the simulation device, and the dynamic stress field of the whole working cycle was calculated. The results show that the additional moment caused by the secondary connecting rod is the main factor that affects the stress of the dangerous part of the main connecting rod shaft. On this basis, considering the influence of the technological condition of the structure surface and other factors, the multiaxial fatigue strength of the main connecting rod was checked based on the critical plane method. The results show that the safety factor of fatigue between the connecting rod shaft and the bulkhead is low, and the calculation of the dangerous point coincides with the actual fatigue crack location.