Usage of Cohesive Elements in Crash Analysis of Large, Bonded Vehicle Structures - Experimental Tests and Simulation

In order to improve structural crashworthiness and reduce vehicle weight, new or modified materials such as advanced high strength steels are increasingly used in vehicle structures. Therefore, material joining issues have become more important. Among the various joining techniques, adhesive bonding is a very successful approach which has brought significant improvements in body-in-white stiffness and vehicle safety. To accurately predict the mechanical responses of vehicle bonded structures in the virtual development process, it is necessary to consider fracture within a joint. For this purpose, a very finely detailed finite element mesh as well as a suitable material model is required. However, in full car simulations the global response of the adhesive layer with an equivalent representation should be taken into account, giving a reliable numerical prediction within an economically acceptable computation time. The objective of this paper is to present a simple way to model failure of adhesive joints, which can be used in real life applications. The article shows that the usage of interface elements together with a cohesive zone model, is a numerically efficient modeling approach, which provides a reasonable correlation between simulation and experimental tests.