Research And Development Of Instrumented Tensile Impact Tester For Spot Welding

Spot welding impact performance testing is an important method to evaluate joints’ dynamic strength, the welding joints’ dynamic strength is also an important indicator to evaluate vehicle’s safety performance. With the development of the times and technology, people’s requirements are increasing on vehicle safety performance. Therefore, it is necessary to carry out reasonable assessment to the dynamic strength of welding joints. The purpose of this study to develop new Spot Impact Tester is to make a reasonable assessment of joints’ dynamic strength.This paper aiming at the research status between our country and abroad about the technology and equipment of spot welding impact testing. Pointed out some problems of spot welding impact testing. Proposed systemic solutions of spot welding impact performance testing, developed an instrumented pendulum impact tester for spot welding impact testing including the body transformation of tester, the welding fixture’s design of specimen, the installation fixture’s design and the impacting fixture’s design, the mechanical test system of spot welding tester is made up of these devices. It is convenient and rapid to prepare specimen and the efficiency of sample preparation is improved.According to the high speed and instantaneous of impact test, configurate and choose a versatile high-speed synchronous data acquisition card, High-speed and high-response force sensor, charge amplifier, High-frequency and high-precision dynamic strain gauge and high-resolution rotary encoder. These devices are compose of data acquisition hardware system of impact tester, It made the test results more accuracy and reliability.According to the requirements of the spot impact test, designed the tester’s control and data acquisition software system, It not only make the tester automatically take pendulum, retreat bolt, impacting, put pendulum and secondary take pendulum come true, but also can draw force-time, velocity-time, displacement-time, force-displacement and impact energy-time curves based on measured data. Obtained the effectively parameters to evaluate the welding joints’ dynamic performance.This study put the developed impact tester into preliminary application, obtained the impact failure modes under different welding conditions, and also received a series of effective parameters and curves characterizing the dynamic performance of the spot welding materials. It is found that the experimental results is basically the same after compared quasi-static tensile test results with the impact test results. That is the bigger nugget size, the better mechanical properties. It is proved that the development of spot welding impact tester has succeed.