The development took place within a federally funded research project, Light eBody (2011-2014).
The project included design and simulation testing of an urban electric vehicle. Bonding was a key joining technology for the multi-material body-in-white (BiW) vehicle. The vehicle’s validation included stiffness and crash performance, in conjunction with aggressive mass reduction targets and the most cost-effective use of materials. Leveraging its market and technology leadership in the field, Dow Automotive Systems has been in charge of “structural adhesives for BiW and assembly” aimed at mass production.
A key task has been the development and validation of computer-aided engineering (CAE) models to predict the mechanical behaviour of bonded parts in a crash. The mechanical performance of the bonded substrates has been tested and evaluated, followed by a detailed material characterisation in order to evaluate the different joining concepts and finally develop the CAE -relevant material characterisation.
Different tasks were performed by the project partners Laboratorium für Werkstoff- und Fügetechnik (LWF, Uni Paderborn), Institut für Schweißtechnik und Fügetechnik (ISF, TH Aachen) and the Institut für Kraftfahrzeuge (ika, TH Aachen). Tests and evaluation were coordinated and analysed by Ford and Volkswagen.
Looking back at the results, Eugenio Toccalino, global director strategic marketing at Dow Automotive Systems, pictured here, stated: “All modern vehicle concepts target mass reduction, independently from powertrain solutions, although lightweight is even more critical for electric vehicles based on added battery content and vehicle range limitations. Extreme mass reduction can only be achieved implementing a mix of the most modern lightweight materials and adhesive technology becomes a key, if not the only joining technology for such material mix assembly.
“As a partner in the Light eBody project, Dow Automotive has not only supplied and evaluated different adhesives formulations, but has developed the material models required to design an urban electric vehicle.”
To join the different body materials, a one-component epoxy adhesive, BETAMATE 1422, was applied for conventional grades and then cured during the e-coat process. For high-strength Boron steel types, a modified version of BETAMATE 1820 structural adhesive was used instead. To enable hybrid constructions- such as thermoplastic substrates and coated metal – the two-component polyurethane adhesive BETAFORCE 2850L was chosen.
