Numerical Analysis of Hybrid Joining in Car Body Applications

Abstract

Nowadays, there are two fundamental issues in car body design. On the one hand, there is the need for weight reduction in order to reduce fuel consumption and, consequently, pollutant emissions, and on the other hand, there are ever more stringent safety requirements. To meet these targets, the trend is towards using hybrid structures made of unconventional materials, like aluminium, polymeric and composite materials. The use of these materials brings about some problems, one of them is associated with the joining techniques because the traditional resistance spot-welding, used in the assembly of a common steel chassis, cannot be used. Among the different alternative solutions, the most promising is the use of structural adhesives. From this perspective, this work aims to model the behaviour of simplified crash box elements made of different types of materials joined together by structural adhesives. In particular, the attention was focused on the adhesive joint modelling with a cohesive element formulation. Starting from experimental results for the characterization of the adhesive, the cohesive parameters were identified. The results were then applied to model the crushing of simplified crash boxes. The crushing axial compression of these components was investigated considering geometrical and loading conditions. The models were developed and verified by comparing the numerical with experimental results on these components. A good correlation was found in all loading conditions and with different geometries and substrate combinations.