超声振动对5A06铝合金自冲铆接头静力学性能影响

Effect of ultrasonic vibration on static properties of 5A06 aluminum alloy self-piercing riveting joints

自冲铆接工艺作为一种性能优异、绿色、高效的连接新技术,可实现同种、异种和多层轻合金薄板材料的连接,广泛应用于新能源汽车等领域,成为实现车身轻量化的关键技术之一。但由于自冲铆接头是典型的紧密连接构件,在交变应力或振动作用下,易发生微动损伤,致使接头提前疲劳失效。本文选用5A06铝合金薄板材料,分别进行自冲铆接和不同超声焊接工具头下的超声自冲铆复合连接试验,基于拉伸-剪切和电子显微镜测试,研究超声振动对5A06铝合金自冲铆接头静力学性能的影响。研究表明:超声振动可有效提高自冲铆接头的静力学性能;超声金属焊接与自冲铆接复合连接时会在板材之间形成固相焊接,这是提高复合接头力学性能的根本原因;超声金属焊接头的焊接面积影响自冲铆接头的力学性能,焊接面积较大时超声固相焊的程度较高;超声焊接会使铆钉温度升高,一定程度影响接头稳定性。

Self-piercing riveting process is a new connection technology with excellent performance,green,and high efficiency.It can realize the connection of the similar,different,and multi-layer light alloy sheet materials and is widely used in new energy vehicles and other fields.Furthermore,it is becoming one of the critical technologies for achieving a lightweight body.However,because the self-piercing riveting joint is a typical tight connection component,fretting damage is prone to occur under the action of alternating stress or vibration,resulting in premature joint fatigue failure.This paper uses 5A06 aluminum alloy sheet material to carry out self-piercing riveting and ultrasonic self-piercing riveting composite connection tests under different ultrasonic welding tool heads.Based on the tensile-shear and electron microscope tests,the effect of ultrasonic vibration on the static properties of 5A06 aluminum alloy self-piercing riveted joints was studied.The results show that:ultrasonic vibration can effectively improve the static properties of self-piercing riveted joints;the ultrasonic metal welding will form a solid phase of welding between the sheets during the compostite self­piercing riveting,which is the fundamental reason for improving the mechanical properties of the combined joint;the area of ultrasonic metal welding joints affects the mechanical properties of self-piercing riveted joints;the degree of ultrasonic solid-phase welding is higher when the welding area is more extensive;ultrasonic welding will increase the temperature of the rivet,which will affect the stability of the joints to a certain extent.