一种新的多轴疲劳寿命预测模型及其应用

A NEW MULTIAXIAL FATIGUE LIFE PREDICTION MODEL AND ITS APPLICATION

机械部件在运行过程中承受多轴循环加载时易发生附加强化效应,采用单轴疲劳寿命计算公式对其寿命进行预测会产生较大误差,而现有多轴疲劳寿命预测模型由于含有大量材料常数也不便于工程应用。针对上述问题,基于不同应力对疲劳微裂纹的萌生、促进作用机制,结合剪切损伤模型,提出一种新的损伤参量表达形式,并结合Manson-Coffin-Basquin方程推导得到对应的多轴疲劳寿命预测模型。采用两种材料在非比例加载、比例加载路径下的实验数据对提出的寿命预测模型进行验证,并与FS(Fatemi-Socie)模型的预测结果进行对比,结果表明,提出的模型具有良好的预测效果。最后将该模型应用于大摆锤吊臂疲劳寿命预测,结果说明吊臂满足疲劳寿命要求。

When mechanical components are subjected to multiaxial cyclic loading during operation,the additional strengthening effect is easy to occur.Using uniaxial fatigue life calculation formula to predict their life will produce large errors.However,the existing multiaxial fatigue life prediction models are not convenient for engineering applications because it contains a large number of material constants.To solve the above problems,based on the initiation and promotion mechanism of fatigue microcracks under different stresses,combined with the shear damage model,a new expression of damage parameters is proposed,and the corresponding multiaxial fatigue life prediction model is derived combined with the Manson⁃Coffin⁃Basquin equation.The test data of two materials under the non⁃proportional loading and proportional loading path are used to verify the proposed life prediction model,and compared with the prediction results of the FS model.The results show that the proposed model has a good prediction effect.Finally,the model is applied to the fatigue life prediction of a big pendulum boom,and the results show that the boom meets the fatigue life requirements.