Abstract
The usage of new power propulsion systems in buses such as hybrid or electric systems change the weight layout inside the bus and therefore modify the bus lateral dynamics. The bus lateral dynamic is greatly influenced by the height of its centre of gravity. If the components used for the new propulsion system are placed higher than in the original vehicle, the height of the centre of gravity of the bus will be increased and its lateral behavior will be worsen. The lateral behavior of a bus is usually characterized by the acceleration threshold which is the maximum lateral acceleration above which the bus would begin the rollover process. In order to evaluate the lateral stability of buses the static rollover threshold (SRT) is usually employed to estimate the lateral threshold acceleration of the bus. The SRT is a function of B, which is the wheeltrack, and h, which is the height of the centre of gravity of the bus. In addition, the new components of the propulsion system might overstress certain beams of the bus structure. In order to evaluate this influence different loading configurations have been implemented in a finite element model of a real bus structure. It is worth outlining that this model has been previously validated by means of static and dynamic experimental tests. The results show that some of the beams cross sections might have to be changed in order to absorb the loading condition derived from the components of the propulsion system.
Keywords: Bus structure, lateral rollover threshold, hybrid power system