影响AlSi9Cu2Mg微动疲劳条件的磨损因素及其寿命预测

Wear numerical assessment on AlSi9Cu2Mg cast aluminum alloy and life prediction

为了探究影响AlSi9Cu2Mg铝硅合金微动磨损的因素以及对磨损状态下该材料的微动寿命进行预测,本文建立了基于Archard弹性理论的网格自适应算法,并进行了摩擦疲劳有限元模拟,讨论了滑移幅度以及磨损分区因子对微动磨损的影响;使用SWT、F多轴疲劳损伤参数与临界距离理论(theory of critical distance)对磨损状态下的微动疲劳寿命进行预测.有限元仿真结果显示,滑移幅度以及磨损分区因子对微动磨损量均产生影响,接触表面在微动接触后缘总是出现压力的峰值,由于接触后缘的应力梯度较大,证明微动裂纹总是发生在接触后缘,与实验观察到的现象一致.通过两种多轴疲劳参数及临界距离理论得到的寿命预测分布显示,无论哪一个参数,考虑磨损时的预测寿命均优于不考虑磨损时的预测寿命,且多轴疲劳参数F在考虑磨损状态下的寿命预测值与实验更为吻合.最终的结果表明,基于Archard磨损定律的自适应网格算法的有限元分析与临界距离理论的损伤参数法相结合的分析流程,可以更为有效地预测AlSi9Cu2Mg的微动疲劳寿命.

To investigate the factors affecting the fretting wear of Al-Si alloys and predict the fretting fatigue life of the material under wearconditions, a finite element simulation of friction fatigue was conducted according to the Archard elastic theory and using theadaptive mesh algorithm. The effects of slip amplitude and wear zone factor on fretting wear were explored. The Smith-Watson-Topper and F multiaxial fatigue damage parameters and the theory of critical distance were used to predict the fretting fatigue lifeunder wear conditions. The results of the finite element simulation showed that the slip amplitude and the wear zone factor bothaffected the fretting wear. The contact surface featured a peak pressure at the fretting contact trailing edge. Because the contacttrailing edge featured a large stress gradient, a fretting crack occurred at the contact trailing edge, consistent with the experimentallyobserved phenomenon. The life prediction distribution obtained according to the two multiaxial fatigue parameters and the criticaldistance theory showed that irrespective of the parameter used for the prediction, the results of life prediction considering wear weremore accurate than the results of life prediction disregarding wear, and the predicted life obtained using the multiaxial fatigueparameter F considering wear was more consistent with the experimental results. Finally, the fretting fatigue life of AlSi9Cu2Mgcould be more effectively predicted via the finite element analysis process combining the adaptive mesh algorithm of Archard’s wearlaw and the F-parameter life equation of the critical distance theory.