金属夹层对自冲铆接头强度和失效形式的影响

基于自冲铆技术,分别制备了铝-铝(A0)、铝-泡沫铁镍夹层-铝(A1)和铝-涂胶泡沫铁镍夹层-铝(A2)的3种自冲铆接头。为研究泡沫金属夹层以及涂胶泡沫金属夹层对自冲铆接头强度及失效形式的影响,通过力学试验测试接头静力学性能,从宏观角度分析接头失效形式,并采用扫描电子显微镜(SEM)对接头失效断口进行微观分析。研究表明:泡沫铁镍金属夹层和涂胶泡沫铁镍金属夹层可有效提高接头静失效载荷,但接头能量吸收值呈下降趋势,A0组接头最大平均失效载荷为3586 N,能量吸收值为11.779 J,A1组和A2组接头静失效载荷比A0组分别提高了9.9%和30%,能量吸收值比A0组分别降低了0.9%和7.2%;3组接头均为拉脱失效,且上板搭接区均出现不同程度的曲翘,A0组接头铆钉从下板拉脱,而A1和A2组接头下板底部与铆钉一并从下板拉脱;3组接头失效模式微观特征为:铆钉腿与铆接孔一侧发生剧烈摩擦和挤压,最终铆钉在拉剪载荷下完全从下板拉脱。

Effect of metal interlayer on strength and failure mode of self-piercing riveting joint

Based on self-piercing riveting technology, three self-piercing riveting joints, aluminum-aluminum (A0), aluminum-foam iron-nickel interlayer-aluminum (A1) and aluminum-coated foamed iron nickel interlayer-aluminum (A2), were prepared. To study the effect of foam metal interlayer and rubber-coated foam metal interlayer on the strength and failure mode of self-piercing riveted joints, the static properties of the joints were examined by mechanical tests, and the failure mode of the joints was clarified from macroscopic viewpoint. Finally, the fracture of the joints was analyzed by scanning electron microscopy (SEM). The results show that the foamed iron-nickel metal interlayer and the rubberized foamed iron-nickel metal interlayer causes a great increase in the static failure load of the joint, and a decrease in the energy absorption value of the joints. The maximum average failure load, and the energy absorption value of the A0 group joint is 3 586 N, and 11.779 J, respectively. The static failure load of the joints of the A1 group and the A2 group is 9.9% and 30% higher than that of the A0 group, respectively whereas the energy absorption value is reduced by 0.9% and 7.2% compared with the A0 group, respectively. All the three groups of joints exhibit pulled out failure feature, and the upper plate overlap area has different levels of warping. The A0 group joint rivets are pulled off from the lower plate whereas the bottom plates of the A1 and A2 joints are pulled together with the rivets from the lower plate. The micro-features of the three groups of joint failure modes are: the rivet leg and the side of the rivet hole experience strong friction and extrusion, and finally the rivet is completely pulled off from the lower plate under the tensile shear load.