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采用5052铝合金单搭自冲铆接头进行疲劳试验,研究了微动疲劳损伤对单搭自冲铆接头疲劳寿命的影响。并运用扫描电镜和能谱仪对接头微动损伤区域进行了微观分析,研究了接头微动疲劳损伤机理。结果表明:在应力比为0.1、最大疲劳载荷为接头拉剪强度的80%时,接头疲劳寿命为36826次;最大疲劳载荷为接头拉剪强度的30%时,达到疲劳寿命极限200万次。接头疲劳寿命与其微动疲劳损伤程度有关,微动疲劳损伤会减弱接头的疲劳寿命。接头疲劳失效形式主要为下板沿铆钉扣处断裂,断裂方向与加载方向垂直。接头微动疲劳损伤过程可分为微动损伤阶段和微动疲劳阶段。在微动损伤阶段,微动磨屑在接头微动接触面不断产生。在微动疲劳阶段,脱层和微裂纹的出现导致接头失效。
The fatigue test of 5052 aluminum single-tap self-piercing riveted joint was carried out to study the influence of fretting fatigue damage on the fatigue life of single-tap self-piercing riveting joint. The microscopic analysis of fretting damage area was carried out by SEM and EDS, and the fretting fatigue mechanism of the joint was studied. The results show that the fatigue life of joints is 36,826 times when the stress ratio is 0.1 and the maximum fatigue load is 80% of the joint tensile strength. When the maximum fatigue load is 30% of the joint tensile strength, the fatigue life reaches 2 million times. Joint fatigue life and its fretting fatigue damage degree, fretting fatigue damage will weaken the joint fatigue life. Fatigue joint failure mainly in the form of the lower plate along the rivet buckle fracture, fracture direction perpendicular to the loading direction. Joint fretting fatigue damage process can be divided into fretting damage stage and fretting fatigue stage. In the stage of fretting damage, fretting fretting constantly occurs on the fretting contact surface of the joint. In the fretting fatigue phase, delamination and the appearance of micro-cracks lead to failure of the joint.