Investigations on a material-specific joining technology for CFRP hybrid joints along the automotive process chain

Abstract

Due to the excellent mechanical properties fiber-reinforced plastics (FRP) are increasingly being used in technical lightweight products in order to achieve a multimaterial design. Due to different melting temperatures, the use of conventional thermal joining technologies is restricted, and the demand of efficient mechanical and adhesive joining technologies is increasing. Within the scope of this publication, the damage behavior of self-piercing riveted hybrid joints using carbon fiber reinforced plastics and metals is analyzed and evaluated in detail regarding the requirements of the automotive industry. Subsequently, hybrid joints are subjected to a thermal profile, which is modelled on the cathodic dip coating drying process in the automotive paint shop. It is shown that the oven process induces damage in the CFRP to self-piercing full riveted joints, which is shown in the form of fiber breaks as well as inter-fiber breaks and delamination. Also, with regard to these effects, geometric optimizations of the self-piercing rivet are carried out, which prevent damages occurring during the oven process. A combination of both optimizations, resulting from the joining and the oven process, leads to a material- and requirement-compliant joining technology, which enables the low-damage joining of CFRP with metals along the automotive process chain.