Accurate Simulation of Door Side Intrusion in Automotive Structures with Progressive Fracture

Door side intrusion (FMVSS 214, Static) is a quasi-static test to determine the sufficiency of door strength and integrity of its mounting in the event of side impact. Explicit nonlinear solutions are often adapted for simulating the side intrusion test performance using the finite element method. The side intrusion performance involves intense rupture at panels as well as their connections such as spot welds, bolts and hems. The load path changes significantly with the material fracture in the panels and at their connections. Conventional finite element models assuming no material separation cannot capture such load path changes and cannot recognize the associated loss in structural integrity. Accordingly, the conventional nonlinear finite element analysis tends to over-predict the intrusion strengths by a large margin and fails to predict the potential separation of the door from the body at the latch and hinge connections.

In this paper, various modes of fractures and their sequence involved in typical side intrusion tests are examined closely, appropriate rupture models are developed for each mode of fracture and an optimal combination of the different rupture models is developed to capture the physical phenomena accurately from structural stiffness, strength and integrity perspectives. The method is tested with many vehicle designs for its accuracy in replicating the material separations and their sequence, and in predicting the door stiffness and strength against side intrusion when in comparison with the corresponding physical tests.