Developing effective parameters for Self-pierce rivet insertion.

The car manufacturing industry is going through a time of significant change under pressure to provide stronger crash safe structures while at the same time making car bodies lighter to enable electric drive. This is forcing car designers to choose very high strength materials and to use a mixture of steel for strength and aluminium for lightness. The result is a large number of riveted joint stack configurations on one car body each requiring different riveting parameters. The amount of physical testing required to find solutions has now become much bigger than the testing time available on the vehicle design programs. To solve this car manufacturers are keen to switch from physical lab testing to simulated joint testing.
There is also pressure on rivet suppliers to rapidly develop new rivets designs for making the new joint stack combinations which are increasingly evolving into higher and higher strength materials. Simulation of rivet designs is needed to accelerate rivet development projects and to conduct process window testing to check the proposed new designs can cope with production variables.
This project first created a validated base model for simulating rivet insertion and then applied this model to a number of research tasks.
Through testing a large number of variety of rivet types, this work developed a set of friction parameters that have proven to work reliably for two different coatings, a standard SPR plating as well as low friction lubricant. The project also focused on accurately replicating the mid-clamping method used by AC setters with promising results. The developed base model been succesfully used to simulate several completely new SPR products that have not been simulated to date such as tubular rivets for standard and narrow flange and solid (swage) riveting.
It has also been utilized in studies focusing on creating a process window for materials to account for manufacturing variables. And finally, the model was used in a study supporting rivet design by bringing together the worst possible combination of lowest rivet manufacturing tolerances in order to predict the worst case scenario in rivet production. The results of this study were particularly accurate and allowed for mitigation of the worst combination of tolerances by informing subsequent rivet geometry amendments.
Following completion of this project, the simulation can be seen as particularly useful tool in design of new products by predicting trends and mapping out process windows for manufacturing variables of both geometries and materials and can potentially replace a large part of physical testing.