The Performance of Adhesive-Bonded Thin-Gauge Sheet Metal Structures with Particular Reference to Box-Section Beams

Abstract

In an effort to reduce vehicle weight, the automotive industry is developing car body structures made from light-weight materials such as composites, plastics and aluminium alloys. Fabrication of these materials in high volume automotive applications using traditional welding techniques is not feasible and adhesive bonding is now being investigated as a potential assembly method. In order to assess performance characteristics of bonded vehicles, thin-gauge sheet-metal box-section beams have been used to simulate structural details in automotive applications such as car bodies and commercial vehicles. Beams were fabricated from flanged strips by different joining methods to form box-section structures approximately lm. long x 60mm. square. Tests were carried out to determine torsional and flexural rigidity and ultimate flexural strengths, and in the majority of tests, bonded structures gave better characteristics than the equivalent riveted or spot-welded beams. The failures of beams under 3-point bending have been related to buckling of the side webs and further experimental tests have shown that collapse is critically dependant on flange-bend radius. Finite element techniques have been used to analyse stress distribution in the beam section and this confirms the experimental observations of beam collapse.