一种引入材料循环本构的单轴疲劳平均应力模型

A mean-stress model including material cyclic constitutive in uniaxial fatigue

为更精准地考虑平均应力对单轴恒幅疲劳寿命的影响,在等效驱动力类平均应力模型的基础上,引入材料循环本构并提出了一个新的平均应力模型。定性地,该模型能够在更广泛寿命值范围和应力比范围内描述多种材料的等寿命线形状;定量地,该模型能够用来预测其他应力比下的疲劳寿命值,且预测值与试验数据符合良好。随后,还提出了一种获取模型系数的方式,能够在保证数据拟合可靠度的前提下进一步减少试验成本。所提出的平均应力模型有潜力为材料性能手册的编纂提供支持,并对相关工程方法提供改进方向。

To precisely consider the effects of mean stress in evaluating uniaxial constant-amplitude fatigue lifetime, this paper proposes a mean-stress model on the basis of driving-force models, and the main idea of proposed model is to introduce material cyclic constitutive. Qualitatively, the model is capable of describing the shapes of constant-life curves for various materials in broader range of given fatigue lifetime as well as cyclic stress ratio;quantitatively, the model is capable of predicting fatigue lifetime under other cyclic stress ratios with satisfying agreements. Moreover, a method to obtain model parameters is also proposed, which further reduces test costs while ensuring the reliability of fitted data. The proposed mean-stress model possesses the potential to provide supports for compiling handbooks of material fatigue properties, and to offer guidelines for improvements of relevant engineering approaches.