Paul Janiak & Taina Vuoristo

Abstract

This project has studied the fatigu strength of mechanical joints with focus on the automotive industry. The projec included both a short initial literature study on fatigue performance of mechanical joints as well as an experimental part with a comparison of fatigue performance of three different mechanical joints; selfpiercing rivets (SPR), RIVTAC® and flow drill screws (FDS).

The experimental part was made on on common material combination DP800 1,5mm joined to an extruded aluminium alloy, AA6082 2,7mm in thickness. Results show that SPR out-performs both FDS and RIVTAC® samples at low and intermediate load levels. SPR and FDS samples are relatively close to each other in fatigue performance with largely overlapping scatter bands (1 standard deviation). RIVTAC® performs clearly worse than both SPR and FDS.

This indicates that the RIVTAC® joint is much more sensitive to fatigue loading compared to both FDS and SPR joints. Worth mentioning is that the mechanical joining techniques evaluated in this study are often used in combination with adhesives in production applications. Thus the results presented in this report only reflect the performance of the individual mechanical joining techniques and not the complete joining solution in a production
environment.