动车铝合金车体焊接接头非线性疲劳累积损伤模型

Nonlinear Fatigue-cumulative Damage Model for Welded Aluminum Alloy Joint of EMU

动车铝合金车体焊接接头疲劳寿命对加载顺序比较敏感,而传统的Miner法无法考虑载荷加载顺序。本文在损伤曲线法的基础上,提出非线性累积损伤模型的数学表达式及参数拟合算法,给出平均应力情况下使用此模型的扩展算式,并对铝合金焊接的对接接头、角接接头进行两级加载实验。实验结果证明:本文模型计算误差小于10%,比传统的Miner模型有更高的精确度,说明这一模型可用于铝合金焊接结构疲劳寿命计算。

The fatigue life of welded joints of EMU aluminum alloy car body is sensitive to loading sequence.The traditional Miner Rule is not able to take into account the loading sequence.On the basis of the damage curve method,the mathematical expression of the nonlinear fatigue-cumulative damage model and the parameter fitting algorithm were put forward in this paper.The extended equation was given when the model was applied with average stresses.Two-step loading tests were made to study the butt joint and corner joints.The results show that the proposed model is featured by a computational error less than 10% in case of any error,a better prediction precision as compared with the traditional Miner Rule,and it is suitable to be applied in life prediction of welded aluminum alloy joints of EMU.