Dynamic strength evaluations for self-piercing rivets and resistance spot welds joining similar and dissimilar metals

This paper summarizes the dynamic joint strength evaluation procedures and the measured dynamic strength data for 13 joint populations of self-piercing rivets (SPR) and resistance spot welds (RSWs) joining similar and dissimilar metals. A state-of-the-art review of the current practice for conducting dynamic tensile/compressive strength tests in different strain rate regimes is first presented, and the generic issues associated with dynamic strength test are addressed. Then, the joint strength testing procedures and fixture designs used in the current study are described, and the typical load versus displacement curves under different loading configurations are presented. Uniqueness of the current data compared with data in the open literature is discussed. The majority of experimental results indicate that joint strength increases with increasing loading rate. However, the strength increase from 4.47 m/s (10 mph) to 8.94 m/s (20 mph) is not as significant as the strength increase from static to 4.47 m/s. It is also found that with increasing loading velocity, displacement to failure decreases for all the joint samples. Therefore, ‘brittleness’ of the joint sample increases with impact velocity. Detailed static and dynamic strength data and the associated energy absorption levels for all the samples in the 13 joint populations are also included.