Development of a Novel Friction Flow Forming Process to Improve Joinability of Lightweight Automotive Structures

This study focuses on addressing the significant challenges faced by the automotive industry in joining lightweight and low ductility materials, such as aluminium and magnesium alloys. These materials are increasingly used to reduce vehicle weight, improve fuel efficiency, and decrease emissions, but pose difficulties in traditional joining techniques due to their mechanical properties.
This research introduces an innovative fastening solution that utilises friction flow forming to enhance the joinability of these challenging material combinations. The novel process generates sufficient heat through friction to locally increase the ductility of the materials at the joint interface, facilitating the formation of robust and reliable joints without the material undergoing fracture and without the bottom sheet being fully pierced, improving corrosion resistance. The study comprehensively evaluates various fastener tip geometries, insertion parameters, and lubrication effects to optimise the joining process for automotive applications.
An extensive experimental setup, including the design and manufacture of prototype fasteners, is employed to assess the performance of the new joining technique under various conditions. Mechanical testing, such as tensile and shear tests, alongside advanced statistical analyses, are conducted to validate the efficacy of the novel fasteners and process parameters. The research findings indicate significant improvements in joinability and understanding of friction forming process behaviours in regards to changes in variables.
Furthermore, the thesis explores the practical application of the developed fasteners in real-world automotive assembly scenarios, highlighting their potential to revolutionise vehicle manufacturing processes. By significantly enhancing the capability to join low ductility materials without compromising structural integrity, this research contributes to the advancement of lightweight automotive design and construction. The research fills gaps in the current body of knowledge in respect to joint geometry contributions to joint performance for flow forming fasteners, the effect of irregularity, process parameters, lubricity and adhesives on joint insertion performance.
Overall, the thesis not only addresses a critical gap in automotive joining technology but also sets the foundation for future innovations in the field, promising more sustainable and efficient vehicle production methods.