考虑缺口效应的多轴疲劳寿命预估模型

为研究缺口构件的多轴疲劳问题,基于损伤力学理论,结合von Mises等效准则的思想,建立一个考虑缺口效应的多轴损伤本构方程,综合考虑正应力和切应力在多轴损伤过程中所起的作用,提出一种适用于缺口件的多轴疲劳寿命预估模型.采用GH4169镍基高温合金、SAE1045钢和LY12CZ铝合金3种材料的缺口件多轴疲劳实验数据对所提出的模型进行评估和验证.结果表明:新模型的精度要高于传统的局部应力应变法,且与实验结果相吻合;同时新模型计算方便,便于工程应用.

A fatigue life prediction model of multi-axial notched specimens with notch effect

In order to study the multi-axial fatigue of notched specimens, based on the theory of damage mechanics and the idea of von Mises equivalent rule, a multi-axial damage constitutive equation considering notch effect was established, which comprehensively considers the effect of normal stress and shear stress in the multi-axial damage process; and further, a multi-axial fatigue life prediction model that can be applied to metal notched parts was proposed in this paper. The model was evaluated by the multi-axial notched fatigue test data of GH4169 nickel-based superalloy, SAE1045 steel and LY12CZ aluminium alloy. The results show that the multi-axial fatigue life predicted by the proposed model was in good agreement with the test results, and the prediction accuracy was significantly improved compared with the traditional local stress strain approach. At the same time, the model is easy to calculate and is convenient for engineering application.