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对取自退役飞机机翼蒙皮的光滑试件进行了等幅疲劳试验,通过疲劳断口分析得到了服役环境下飞机主体材料LY12CZ铝合金蚀坑的拓扑特征。基于飞机结构的实际腐蚀尺寸,将蚀坑的宽度和深度作为等效裂纹的长轴和短轴,并应用Stress Check软件对蚀坑等效为裂纹的可行性进行了有限元分析。结果表明:实际蚀坑与等效裂纹对结构应力分布的影响十分相似;应力强度因子在蚀坑等效前后数值大小和变化趋势不大。在分析蚀坑对典型试件疲劳寿命影响时将蚀坑等效成半椭圆形裂纹,选取Walker公式作为扩展速率模型,并与试验值进行了对比。结果表明:预测值与试验值比较吻合,最大误差为9.23%,满足工程需求。
The fatigue test of the smooth specimens taken from the wing skin of decommissioned aircraft was carried out. The topological characteristics of LY12CZ aluminum alloy corrosion pits of aircraft main body under service environment were obtained by fatigue fracture analysis. Based on the actual corrosion size of the aircraft structure, the width and depth of the pits are taken as the long and short axes of the equivalent cracks. Stress Crack software is used to analyze the feasibility of the equivalent pits crack. The results show that the influence of actual pits and equivalent cracks on the structural stress distribution is very similar. The values of stress intensity factor before and after the equivalent pits are not significant. In the analysis of the influence of pits on the fatigue life of the typical specimens, the pits are equivalent to semi-elliptical cracks. The Walker’s formula is chosen as the model of the extended velocity and compared with the experimental data. The results show that the predicted value is in good agreement with the experimental value, the maximum error is 9.23%, which meets the engineering requirements.