Comparative analysis of bus rollover protection under existing standards

Both Europe and the United States (US) have enforced the legislations for bus rollover protection: Regulation number 66 of the Economic Commission for Europe (ECE R66) and standard number 220 of the American Federal Motor Vehicle Safety Standards (FMVSS 220) in order to prevent catastrophic rollover accidents. Therefore, this paper studied the legislation for bus rollover protection including both ECE R66 and FMVSS 220. Satisfying the rollover requirements by buses is obligatory by law. However, the scope of those two regulations does overlap for some group of vehicles. Thus, this study firstly presents a physical meaning comparative analysis of the ECE R66 with the FMVSS 220. The LS-DYNA 971/MPP was used for numerical analysis. The analysis models were constructed by the eta/FEMB that is a preprocessing module integrated in the LS-DYNA 971 package. The validation was turned from experimental data of body knots extracted from the real vehicle. This investigation performed the comparative analysis following ECE R66 and FMVSS 220 assessments, then moved to demonstrate the distortion configuration of the vehicle superstructure through the absorbed energy and its distribution in the vehicle and the vehicle frame sections, as well as the violation of the passenger compartment under the rollover testing conditions of both ECE R66 and FMVSS 220. Great differences were found between the rollover strength of bus superstructures depending on which regulations are followed. The results also demonstrate that the passenger compartment and residual space are more violated and more dangerous under the lateral rollover testing condition of the ECE R66 than the other. Above findings could be used for the automobile manufacturers in a new design of bus superstructure, incorporating the rollover safety legislation and lightweight designs.