断裂力学在直升机桨毂上的应用

 本文用实验方法,得出了计算弯曲载荷下含表面裂纹圆轴、圆筒的应力强度因子（K_I）的表达式,并按照裂纹面积扩展率公式,分析了直升机桨毂转轴轴颈的临界裂纹面积和剩余疲劳寿命。为了校核断裂力学分析的可靠性,模拟飞行状况进行了实际桨毂支臂转轴轴颈的疲劳试验。实验结果与计算结果相当符合。

APPLICATION OF FRACTURE MECHANICS TO HUB-ARMS OF HELICOPTER

The fracture of journal in hub-arms of helicopter has been analyzed on the basis of fracture mechanics. For simplicity the journal can be regarded as a cylinder with a transverse surface crack under bending load. Taking the crack area S0 as a main parameter, we have obtained the compliance of the cylinder λ , the energy release rate G and the stress intensity factor KI from the experimental data.It was found that （da）/（dN） could not give a complete expression forthe features of the fatigue crack propagation in the cylinder with a transverse surface crack, so it was suggested to adopt the area rate of fatiguecrack propagation （ds）/（dN） = C （△W1）n for this purpose. The experimentalinvestigation on the fatigue surface propagation of different specimens confirmed this formula.The critical crack propagation area and the residual life expectancy of the journal were discussed on the basis of the theoretical analysis and experimental investigation. Structural fatigue tests verified that the results obtained by the presented method were in good agreement with tests data.