夹层结构自冲铆接头疲劳性能的研究  

Fatigue properties of self-piercing riveted joint with sandwich structure

作　　者：丁文有 何晓聪[1] 刘佳沐 刘洋[1] DING Wenyou;HE Xiaocong;LIU Jiamu;LIU Yang(Faeuhy of Mechanical and Electrical Engineering,Kunming University of Science and Technology,Kunming 650500,China)

机构地区：[1]昆明理工大学机电工程学院,云南昆明650500

出　　处：《兵器材料科学与工程》2019年第1期118-122,共5页Ordnance Material Science and Engineering

基　　金：国家自然科学基金(51565023;51565022)

摘　　要：以不同泡沫金属为夹层进行自冲铆接头疲劳试验,采用二参数威布尔分布检验疲劳数据,并拟合各组试样的S-N曲线。用扫描电子显微镜观测不同疲劳区接头的典型疲劳断口,分析裂纹萌生形式,研究接头在不同应力下的失效机理。结果表明:以泡沫镍为夹层的接头疲劳寿命明显优于泡沫铁镍为夹层的接头;泡沫镍在微动过程中迁移流动能力较强,在磨屑床中起第三体润滑承载作用;接头的疲劳裂纹萌生于接头的铆接点下板或铆孔中心的下板一侧区域;铝合金疲劳源区晶粒滑移呈不均匀性,疲劳裂纹萌生于金属夹杂物、第二相处;接头的裂纹扩展区可观察到大量密集分布的疲劳条带,并伴有较深的二次裂纹;在瞬断区,铝合金自冲铆接头呈韧窝形貌。Fatigue experiments were carried out on self-piercing riveted(SPR)joints with different foam metal as inter-layers.The obtained data were tested by two-parameter Weibull distribution method.The S-N curve of each specimen was fitted by S-N curve fitting method.In addition,the fatigue crack initiation mode of the joint was analyzed.Typical fatigue fractures of joints located in different fatigue life zones were observed by scanning electron microscopy(SEM).The failure mechanism of the joint under different stress levels was explored.The results show that the foam metal inter-layer significantly affects the fatigue characteristics of the self-piercing riveted joint.The fatigue life of the joint with nickel foam as the inter-layer is obviously higher than that of the joint with iron and nickel foam.The nickel foam has a strong ability to migrate and flow during the fretting process,and plays a lubrication role in the grinding bed as a third body.The fatigue crack of the joint is initiated in the lower plate of the riveting area of the joint or the lower plate area on the side of the riveting area.The slip behavior of the grain of the aluminium alloy in the fatigue source region exhibits an uneven characteristic.Fatigue cracks are initiated at the location of the metal inclusions and the second phase particles.A large number of densely distributed fatigue strips are observed in the crack propagation region of the joint,accompanied by deep secondary cracks.The aluminum alloy SPR joint presents a dimple morphology in the instantaneous break area.

关 键 词：自冲铆 泡沫夹层 扫描电子显微镜 疲劳特性 疲劳断口 

分 类 号：TG386.41[金属学及工艺—金属压力加工]