多轴疲劳寿命模型建立新方法

A new establishing method of multi-axial fatigue life model

摘要:

为解决多轴疲劳寿命估算问题,提出一种建立多轴疲劳寿命预测模型的新思路和新方法. 采用对单轴和多轴疲劳试验数据的共同拟合和优化方法建立多轴疲劳寿命模型,减少了对多轴疲劳损伤参数构造和疲劳试验数据类型的限制. 基于最大剪应变幅及最大剪应变幅平面上的法向应力和应变构造了一种新的多轴疲劳损伤参数. 采用ZTC4铸造钛合金、纯Ti、BT9钛合金3种材料的多轴疲劳试验数据对上述多轴疲劳寿命模型建立方法进行了评估和验证. 结果表明提出的多轴疲劳寿命模型建立方法是可行的,所建立的寿命模型对多轴疲劳试验数据的预测能力基本在2倍分散带之内.

Abstract:

To solve the problem of prediction of multi-axial fatigue life, a new thought and method of establishing multi-axial fatigue life model is proposed. The multi-axial fatigue life model is established by fitting and optimizing axial and multi-axial test data both. This method reduces the restrictions of the formation of multi-axial fatigue damage parameters and the type of multi-axial fatigue test data. On this basis, a new multi-axial fatigue damage parameter based on maximum shear strain amplitude and normal strain and stress on the plane of maximum shear strain amplitude is proposed. The establishing method of multi-axial fatigue life model is evaluated by the multi-axial fatigue test data of ZTC4 cast titanium alloy, pure titanium and BT9 titanium alloy. The result shows that the new method is feasible. The prediction ability of the establishing life model is almost within a factor of two scatter band.