Abstract
Lightweight construction methods will make a significant contribution to sustainable CO2 reduction in new car body developments. Multi-material design offers cost-efficient lightweight solutions for car mass production. The key to successfully drive this development trend is a particularly economical, safe and sustainable joining technique: adhesive bonding. In automotive production, the car body must be heated in an oven to ensure the curing process of the adhesives. The increase in temperature leads to different expansion performance of adherends according to their individual thermal expansion behaviour. Stresses occurring may be so great as to cause plastic deformation in the joint area. During cooling of the bonded construction, further relative displacements occur between the joint partners, which can lead to joint failure. These effects influence the usability, sustainability and long-term durability of adhesively bonded components and have not yet been considered for use in automotive car body design. As part of a research project, a test stand was built to allow adhesive bonds to be cured under diverse selected temperature-time profiles e.g. to simulate the cathodic dip-paint process. Various degrees of adhesive curing can be realized and the influence on the joint evaluated in a subsequent tensile test. Parameters such as the maximum strength or displacement at fracture, but also the plastic deformation behaviour of the used toughened adhesive system, depend on the degree of curing. Temperature-related relative displacements are simulated by applying an additional mechanical stress during adhesive curing. Their influence on the mechanical properties of the adhesive bond is evaluated in a subsequent tensile test. There is a significant influence of relative displacement on the mechanical behaviour of the adhesive joint during adhesive curing.
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The IGF research project 369 ZN (FOSTA P 878) by Forschungsvereinigung Stahlanwendung e.V. - FOSTA, Sohnstraße 65, 40237 Düsseldorf, Germany, is funded by the AiF under the programme for promotion of industrial research (IGF) by the Federal Ministry for Economic Affairs and Energy based on a decision of the German Bundestag.
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Doc. IIW-2507, recommended for publication by Commission XVI “Polymer Joining and Adhesive Technology.”
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Meschut, G., Hahn, O. & Teutenberg, D. Influence of the curing process on joint strength of a toughened heat-curing adhesive. Weld World 59, 209–216 (2015). https://doi.org/10.1007/s40194-014-0195-y
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DOI: https://doi.org/10.1007/s40194-014-0195-y