基于临界平面法的多轴疲劳寿命估算模型研究

基于临界平面法，分析了WB模型的缺陷，发现：WB模型中的法向应变变程不能很好的反映材料非比例循环加载下的附加强化现象，且模型中的经验常数是一个与寿命相关的参数，该参数不能简单的利用拉伸和扭转疲劳极限来确定。为克服WB模型的缺陷，提出了一个新的多轴疲劳损伤参量，引入了一个新的应力相关因子，建立了新的寿命估算模型。新的损伤参量不含经验常数，应力相关因子能够反映材料非比例循环加载下的附加强化现象，所建模型能够精确估算材料的多轴疲劳寿命，便于工程应用。

Study on the multiaxial fatigue life prediction model based on the critical plane approach

Based on the critical plane approach, the drawbacks of the WB model are analyzed. It is discovered that, the normal strain excursion between adjacent turning points of the maximum of shear strain cannot reflect the effects of the additional cyclic hardening well; in the meantime, the empirical constant contained in the WB model is a life-correlated parameter which cannot be completely determined by the tensional and torsional fatigue limit. In addition, a new multiaxial fatigue damage parameter is developed to overcome the drawbacks of the WB model. The new damage parameter integrates the strain parameter with the energy parameter which the normalized stress range is used, and moreover, a new stress-correlated factor is introduced to account for the additional cyclic hardening which were caused by the non-proportional loading. It is convenient for engineering application because of no empirical constants in this parameter.