铸造铝合金镦粗挤压铆接接头失效形式和强度的分析

镦粗挤压铆接是针对铸造件的连接提出的一种铆接技术，从失效形式和强度两个方面对镦粗挤压铆接得到的接头性能进行分析，通过改变冲头直径和深度，采用正交试验，得到不同的试验组合。基于体积不变原理，计算出各个试验组合下需要的铆钉高度，进行镦粗挤压铆接试验，对铆接得到的试件进行剪切和拉伸试验。根据试验结果，分析接头的失效形式，并且绘制出接头的失效极限图，最后分析了冲头尺寸对接头抗剪强度和抗拉强度的影响。研究结果表明：采用镦粗挤压铆接方法得到的接头，其抗剪强度高于抗拉强度；剪切载荷下，接头只发生根部剪断失效；拉伸载荷下，接头发生头部剥离、头部剪断和铆钉根部拉断失效。

Analysis on failure modes and strength for upset protrusion riveted joints of casting aluminum alloy

Upset protrusion riveting method was used to join castings. The performance of joint obtained by the method upsetting-extrusion was analyzed based on the failure modes and strength. The various testing schemes were obtained through orthogonal test method by chan-ging diameters and depths of the punch. Furthermore, based on the principle of constant volume, rivet heights under different test schemes were calculated, and the upset protrusion riveting tests were carried out. Then, it was conducted the shearing and tensile tests of parts. According to the results, the failure modes were analyzed and the failure limit diagram of joints was obtained. At last, the effects of the geometrical dimensions of the punch on the shear strength and tensile strength of joints were studied. The results show that the tensile strength of joints is lower than the shear strength;joints occur to shearing failure on tail under the shear loading. However, joints occur to head peeling, head shearing and joint pulling failure on tail under the tensile loading.