On the hybridization of double-flush riveting with adhesive bonding

¹ IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Portugal
² CIMOSM, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, Portugal

^* Corresponding author: joao.pragana@tecnico.ulisboa.pt

Abstract

This paper investigates the feasibility of combining the principles of a novel joining-by-forming process, known as double-flush riveting, with those of adhesive bonding to produce hybrid joints with enhanced characteristics. The study focuses on unit cells consisting of lap joints between 2 mm steel sheets, fabricated using: (i) commercial high-performance adhesives, (ii) solid rivets, or (iii) a combination of both. The experimental workplan begins with identifying the optimal conditions for surface preparation and curing to achieve sound adhesive-bonded unit cells. A similar approach is applied to double-flush riveted unit cells, focusing on the geometric variables of the process. Hybrid unit cells are constructed following a sequence that starts with adhesive bonding and concludes with double-flush riveting. Results are supported by finite element analysis using an in-house computer program and focus on the construction of the unit cells as well as destructive testing through lap-shear tests. The findings confirm that, although hybrid joints are more complex to produce due to the integration of two distinct joining processes, they ultimately provide greater joint strength making them promising solution for demanding applications where durability and reliability are paramount.