45钢轴的疲劳断裂分析

45钢轴在台架试验过程中发生断裂，对失效件进行外观观察、断口宏微观观察，结合零件在试验过程中的受力状况，判断该轴属扭转疲劳断裂，断裂位于沟槽处，该部位存在应力集中效应，且表面未经强化处理，并对轴的最大切应力和疲劳寿命的安全系数进行计算。结果表明:轴的疲劳开裂与沟槽导致的应力集中系数提高以及表面未经强化有关，随着循环载荷的作用，裂纹不断扩展直至断裂。

Fatigue Fracture Analysis of 45 Steel Shaft

45 steel shaft fractured during bench test.Macro and micro observation, combined with analysis on stress condition during test, was carried out to find out the failure mode and cause.In addition, the shear stress and security coefficient during fatigue test were calculated.The results show that the failure mode of the shaft is torsional fatigue fracture.The crack area has a groove, which resulted in stress-focusing effect, and has no surface hardening treatment.These two factors are the main cause for the fracture of the shaft.