Abstract
When a motor vehicle is circulating in a curve, its road safety depends on different parameters related to vehicle. design, operation conditions (speed, load state, etc.) and the roadway geometry (curve radius, lateral adherence, etc.).
All of them may be summarized in a main parameter: the rollover limit or the highest lateral acceleration that a vehicle can reach without overturning.
Experimental test for dynamic measurement of rollover limit of a bus is almost impossible and very expensive. Also, its determination from the Tilt Table Ratio suffers from reduced normal forces acting on the suspension when inclining the gravitational acceleration.
Most of the rollover calculation models are based on two-dimensional system. Those models don't consider that one of the wheels of the shafts lifts prematurely. This simplification is only acceptable when all the shafts elevate simultaneously due to a high rigidity body. Three-dimensional models don't have into account the lateral rigidity of the tires (a very important parameter for estimating of rollover lateral acceleration) or they don't consider some terms of the equations (for example sinus and cosines of high angles). Also, they disregard the possibility that the roll center or the center of gravity is far from the longitudinal middle plane of the vehicle.
In this paper a calculation procedure is presented. First, the dynamics lateral conditions when a bus circulates in curve are represented, second, the rollover limit after some dynamics experiments are calculated. The knowledge of this value will increase the safety of these vehicles.