多轴疲劳寿命预测及验证

Fatigue Life Prediction Under Multiaxial Loading

以薄壁管试件为研究对象 ,分析了拉扭联合加载作用下的多轴疲劳应变变化特性·根据多轴疲劳临界平面法原理 ,以临界平面上最大剪应变幅、正应变幅以及表征材料总体损伤水平的非比例度为参数建立多轴疲劳损伤参量 ,结合Manson Coffin方程建立了多轴疲劳寿命预测模型·该模型考虑了材料总体损伤程度·模型中表征材料总体损伤的非比例度是加载参数的函数 ,与多轴疲劳应变变化特性密切相关·试验验证 ,预测寿命误差因子小于 1 5 ·

The strain varying characteristics of multiaxial fatigue were analyzed under the condition of combined tensional and torsional loading for thin walled tubuar specimens. Based on the principle of multiaxial critical plane approach, a multiaxial fatigue damage parameter was established, which takes account for the effect of not only the maximum shear strain amplitude and normal strain amplitude on the critical plane but also the parameter of non proportionality. The non proportionality can indicate the whole damage level of materials and is the function of loading parameters which is closely contact with the strain varying characteristics of multiaxial fatigue. The experiments under the tension-torsion proportional and non proportional loading were conducted to verify the multiaxial fatigue life model. The life prediction has a good correlation with the experimental results.