An Investigation on the Roll-Over Crashworthiness of an Intercity Coach, Influence of Seat Structure and Passenger Weight

A roll-over event is one of the most crucial hazards for the safety of passengers and the crew riding in a bus. In the past years it was observed after the accidents that the deforming body structure seriously threatens the lives of the passengers, thus the roll-over strength has become an important issue for bus and coach manufacturers. Today the European regulation “ECE-R66” is in force to prevent catastrophic consequences of such roll-over accidents thereby ensuring the safety of bus and coach passengers. According to the said regulation the certification can be gained either by full-scale vehicle testing, or by calculation techniques based on advanced numerical methods(i.e. non-linear explicit dynamic finite element analysis). The quantity of interest at the end is the bending deformation enabling engineers to investigate whether there is any intrusion in the passenger survival space(residual space) along the entire vehicle. In this paper, explicit dynamic ECE-R66 roll-over crash analyses of a stainless-steel bus under development were performed and the strength of the vehicle is assessed with respect to the requirements of the official regulation. Subsequently, different considerations which are not currently mentioned in the regulation (i.e. passenger and luggage weight) and some worst case assumptions such as the influence of the seat structure were investigated. The non-linear explicit dynamics code LS-DYNA as a solver and ANSA and LS-PREPOST softwares as FEA pre/post- processors were utilized throughout the bus roll-over analysis project. The FEA model was generated by using PCs running on Linux Suse operating system whereas the LS-DYNA solutions were performed on a multiple-processor workstation running on an AIX UNIX operating system. During the first stage, a verification of the calculation procedure following regulation ECE-R66 was performed. The verification of calculation is a compulsory requirement of the regulation, as it is the technical service’s responsibility(TÜV Süddeutschland in this case) to verify the assumptions used in the finite element analysis.