Composite Test Procedure for Side impact Protection 871117

The current proposals for defining a test procedure for side impact can be divided into two general groups:

• Component/Sub-System Tests
• Full-Scale Tests.

The advantage of the former test procedure is that it provides a statement on a manageable group of vehicle components or sub-assemblies. This means that they can be designed in such a way that they are more suitable for the wide range of accidents which occur (collision directions, impact points) than a full-scale test, which provides an exact simulation of only one single defined accident. The advantage of the full scale test is that it provides an integrated statement about the protective potential of the structural stiffness of the impacting and impacted vehicle in conjunction with the padding features for the selected type of collision and the selected collision speed. This is the reason why many of the automobile manufacuters have come out in in favour of the full-scale test. The evaluation of the protective potential of vehicle characteristics in the full-scale test however also depends on the quality of the dummies used. The requirement here is that the mechanical behaviour of the dummy should be as close as possible to that of human occupants in the event of a collision. However, the better a dummy meets these requirements, the more complex is its mechanical structure, and there is a greater risk that reproducibility of full-scale tests will deteriorate.

Another consequence of more complex dummies is the increased demand for calibration and repair. This will result in an increase in the time required to develop a vehicle and the overall cost of development will increase.

The test procedure presented in this paper is an attempt to combine the advantages of component and full-scale tests, without having to accept any of their inherent disadvantages.

In accordance with the component test procedure proposed by MVMA, a deformable ram is initially used in a separate test to load the side structure from the exterior until the door makes contact with the seat. In a subsequent phase, a stiff body ram is pressed against the door from the interior and the force-deflection curve is measured. In a third phase, the exterior ram is driven further into the side structure until the integral of the measured force-deflection curve corresponds to the deformation energy of a full-scale test to be simulated. With the exterior and interior stiffness obtained in this way, the full-scale test is simulated using computer simulation and the load on the dummy is calculated.

In contrast to the MVMA proposal, the effect of structure and padding features for enhancing existing occupant protection and the interactions thereof is considered in the new composite test procedure. This gives the designer access to more options for maximising side impact protection.