单轴非线性连续疲劳损伤累积模型的研究

首先在连续疲劳损伤理论的基础上，根据疲劳损伤过程中金属材料韧性的变化特点，建立一种新的非线性疲劳损伤累积模型。该模型考虑了疲劳极限、平均应力以及损伤参量与加载参数的不可分离的特点，并且能够反映出加载顺序的影响。然后推导出该疲劳损伤累积模型在多级加载下的递推公式。经３种金属材料的疲劳试验数据验证结果表明，用该模型预测疲劳寿命，其结果令人满意的。

STUDY ON NONLINEAR CONTINUOUS DAMAGE CUMULATIVE MODEL FOR UNIAXIAL FATIGUE

On the basis of the continuum fatigue damage theory, a new nonlinear fatigue damage cumulative model is proposed by the defined fatigue damage variable by means of the varying behavior of the material ductility in the process of fatigue damage. The fatigue limit, mean stress and the unseparable characteristic for the damage variables and the loading parameter are considered by the proposed fatigue damage cumulative model, and the effect of the loading sequence is also included. The characteristic of the nonlinear accumulation for fatigue damage may be reflected in this model. A fatigue damage evolution equation is derived, which can describe the fatigue damage evolution behaviour well. The recurrence formula of the fatigue damage model is derived under multilevel loading, and the loading case below the fatigue limit is also considered. The fatigue test data for three kinds of material were used to verify the model proposed in this paper. The results show that good agreement is achieved with this model to predict fatigue life, compared with that of Miner's rule.