Investigation of the friction conditions of self-pierce rivets by means of a compression-torsion tribometer

Abstract

Lightweight design is an effective lever for achieving fuel consumption and emission-oriented goals. Therefore micro-alloyed steels and high-strength aluminium materials are included in the multi-material mix of the car body. In this context self-pierce riveting has become established for joining in body-in-white production. For the dimensioning of the joint, numerical simulation is increasingly being used. In order to make reliable predictions about joint quality, knowledge of the friction in the joining process is necessary and needs to be identified experimentally. In previous investigations, the process parameters in the friction test were not comparable to the joining process. Therefore, a new friction test method is presented in this paper, where the process conditions are comparable between joining and friction testing especially regarding the interface pressure. The local joining process parameters between rivet and sheet are derived numerically. In the framework of the investigations, the influences of the local joining process parameters, like interface pressure, relative velocity and temperature, on the friction are investigated and mapped close to the joining process. Additionally a comparison of different rivet coatings is carried out. The rivet contact to the sheet metal HX340LAD as well with aluminium EN AW-5182 is taken into account.

Experimental and Numerical Investigations on the Impact of Surface Conditions on Self-Piercing Riveted Joint Quality

“…It was found that friction coefficients between the die and bottom sheet and between the rivet and top sheet had the most significant influences on the joint quality. Suitable friction coefficients for the studied SPR To overcome the disadvantages of the experimental approach, numerical analyses with a finite element (FE) model have also been conducted in some studies to explore the impact of surface conditions [15,16]. It has been widely proved that a properly calibrated FE model of the SPR process can accurately predict the riveting force [17], material deformation behaviour [18] and final joint quality [19].…”