Virtual testing for the assessment of a double-sided roof crush based on the newly updated Federal Motor Vehicle Safety Standard 216

Abstract

The newly updated Federal Motor Vehicle Safety Standard 216 enhances the requirements of the roof crush behaviour as it particularly focuses on the double-sided test protocol. This test will be mandatory from the year 2012 and will replace the single-sided test. The research presented herein aims at investigating the behaviour of a small European vehicle subjected to this newly updated Federal Motor Vehicle Safety Standard 216 and at assessing the effect of the variation in the loading combination of the pitch angle and the roll angle on the roof crush strength to quantify the difference in the performances. A Ford Fiesta FE model developed at the University of Bolton was refined and validated against the roof crush test. Thereafter a full factorial method was employed to the design of the experiment based on varying the pitch angle and the roll angle. The response functions concerning the resistance force of the double-sided roof were hence constructed with the results from a series of virtual tests based on nine levels of the roll angle and four levels of the pitch angle. Parametric studies were then conducted with respect to the effects of the body structural components, the windscreen and the variations in the roll angle and the pitch angle on the roof strength. The results show that the roll angle and the pitch angle are functions of the roof strength. In general, the roof on the near side performs in a stronger way than the roof on the far side and greatly influences the overall collapse behaviour. Within a crush distance of 127 mm (5 in), the strengths on both sides of the roof decrease as the roll angle varies from 10° to 45°. The variation in the pitch angle influences the resistance force. In addition, the windscreen is found to contribute significantly to the roof strength on the far side, hence demonstrating a strength which is artificially high, not quantifiable and not observed in real-world rollover crashes. From the virtual parametric analysis carried out, it shows once again that the recommended loading-angle combinations in the newly updated Federal Motor Vehicle Safety Standard 216 roof crush test should be a roll angle of 45° (and not 25°) and a pitch angle of 10° (and not 5°) for both near-side and far-side roof load application.