Crash-modified two-component adhesives for joining CFRP and aluminium in automotive body in white

Abstract

In this paper, the results of a publicly funded project will be presented. The aim of this project is to investigate the use of two-component (2C), crash-modified (CM) adhesives for joining fibre-reinforced plastics (FRPs) in the process of body in white (BIW). For the assembly of car bodies, special structural adhesives are necessary, combining high strength with the ability to dissipate energy in case of crashes. Most of the used adhesives are single-component (1C) and cure thermally. 2C adhesives which cure at room temperature and are currently used for maintenance and repair feature many benefits compared to hot curing 1C systems in the online BIW production process. However, until now, the application of CM 2C adhesives used to join FRP has not been sufficiently examined, especially with regard to the cataphoretic process. Therefore, this work investigates different process parameters in the BIW production process, which influence the properties of the selected crash-optimised 2C adhesives as well as the characteristics of the bond. The selected 2C adhesives were characterised with respect to their quasi-static and dynamic properties under conditions that occur in the cataphoretic process and application. For mixed materials and the temperature program in the CDP process, shear stresses and strains influence the performance of the bond. Therefore, measurements were carried out to evaluate the effects caused by the temperature program. Furthermore, the methods of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to demonstrate effects of the BIW process on the adhesive properties as well as the ability of 2C adhesives to be fast cured at elevated temperatures.