基于损伤权重的混合多钉连接件疲劳寿命预测方法

复合材料与金属材料混合多钉连接形式是当代飞机结构中最常见的连接形式，因此对于混合多钉连接件疲劳性能的研究有助于提高对飞机结构疲劳损伤的认知。针对以Ti-6Al-4V钛合金为螺栓的ZT7H/QY9611碳纤维增强树脂基复合材料连接板与30CrMnSiNi2A金属连接板混合多钉连接结构进行数值分析和试验研究。利用有限元方法，分别对复合材料和紧固件进行疲劳损伤预测，估算复合材料连接板上螺栓孔附近的损伤，依据复合材料和紧固件的损伤量所占权重，提出了以紧固件分布和复合材料连接板铺层层数为参数的经验公式，进而有效提高混合多钉连接结构疲劳寿命的预测精度。利用试验结果将螺栓孔损伤形式进行分类讨论，探索混合多钉连接件的损伤演化方式；利用C扫描技术得到复合材料分层损伤结果，与模拟结果进行对比分析，进一步解释了模型的合理性。与试验结果对比可以看到，考虑损伤权重的寿命预测值与试验值的对数误差仅为1.1%，相对于不考虑损伤权重方法的8.4%的对数误差，该模型寿命预测精度显著提高。

Fatigue life prediction method for hybrid multi-bolted joints based on damage weight

The composite and metal material hybrid multi-bolted joints are the most common connection form in contemporary aircraft structures. Research on the fatigue performance of the hybrid multi-bolted joints helps to improve the understanding of the aircraft structure fatigue damage. A numerical analysis and an experimental study on the multi-nail connection structure of the ZT7H/QY9611 carbon fiber reinforced resin matrix composite plate and the 30CrMnSiNi2A metal plate with Ti-6Al-4V titanium alloy as bolts are conducted. The finite element method is used to predict the fatigue damage of the composite materials and fasteners, respectively, and simulate the damage near the nail holes on the composite material plate. An empirical formula with the distribution of fasteners and the number of layers of the composite material plate as parameters is proposed to accurately estimate the damage weight of the composite materials and fasteners, thereby effectively improving the accuracy of fatigue life prediction of hybrid multi-bolted joint structures. Through categorization and discussion of the damage patterns of nail holes based on the experimental results, the damage evolution of hybrid multi-nail connectors is explored; C-scan technology is adopted to detect layered damage of the composite materials which is compared with the simulation results to further verify the model. Compared with the experiment value, the logarithmic error of the life prediction simulation value considering the damage weight is only 1.1%, which is a significant increase from 8.4% of the method without considering the damage weight.