钛合金疲劳小裂纹扩展行为预报方法研究

Prediction method of the small crack growth and life for titanium alloys

针对小裂纹扩展阶段裂纹尖端塑性区域尺寸相对于小裂纹长度是不可忽略的问题,在考虑小裂纹效应裂纹扩展速率修正模型基础上,对该模型中裂纹尺寸进行修正,即裂纹长度等于真实裂纹长度加上平面应变状态下裂纹尖端塑性区域一半;并利用修正后的模型对钛合金材料不同情况下疲劳小裂纹扩展速率和寿命进行预报,同时将预报结果与试验值比较。结果表明:修正后的预报模型对小裂纹扩展速率和寿命均有很好的预报效果。

The prediction method of the small crack growth is modified based on the life prediction model produced by Wang Ke. The characteristics and mechanism of short fatigue cracks propagation are systematically considered, the modi- fied crack size equals the real crack length plus a half of the crack tip plastic area, which is in the plane strain state. Further- more, the small crack growth rates and lives of titanium alloy smooth specimens in different conditions are predicted by us- ing this relation, which are compared with the test data. The results show that the modified model has a good effect on pre- dicting the small crack growth rate and life.