考虑裂纹形状变化的TC4钛合金振动疲劳裂纹扩展寿命预测

Vibration fatigue crack growth life prediction of TC4 titanium alloy by considering the influence of crack shape

对TC4板材试件进行振动疲劳裂纹扩展试验,测得裂纹扩展寿命与裂纹长度之间的关系.使用超景深显微镜对裂纹形状进行观测和分析,拟合裂纹形状参数.将拟合表达式应用于应力强度因子幅值的计算中,并对裂纹扩展寿命进行预测.结果显示:裂纹形状参数对预测结果影响较大.当该参数取定值时,预测结果与试验结果误差较大.而所拟合的拟合表达式可以简单、准确地预测裂纹扩展寿命.

Based on the tests about vibration fatigue crack growth of TC4 plate,the relationship between crack growth life and crack length was got.Using the ultra-depth microscope to observe and analyze the crack shape,the crack shape parameter was fitted.The fitted parameter was applied to calculate the stress intensity factor range and predict the crack growth life.Comparing the test results with prediction results,it showed that the crack shape parameter greatly influenced the predicting results.When the parameter was given a constant value,the error between the prediction and tested results was large.However,the fitted crack shape parameter can be used to predicted the crack growth life much more conveniently and accurately.