Influence of suspension parameters on a tilt angle of passenger bus for the stability test

Abstract

Passenger bus stability testing is frequently conducted in accordance with a regulation standard of the Economic Commission for Europe of the United Nations. Specifically, this standard defines a test that requires the vehicle to be titled to either side at an angle of 28 degrees from the horizontal without overturning. Generally, the stability of a vehicle at this tilt angle is primarily affected by the height of the center of gravity as well as the suspension system. This paper explains a study of several parameters influencing the tilt angle stability test of the passenger bus to avoid bus accident caused by a rollover. The parameters consisted of the spring stiffness, damping coefficient, anti-roll bar stiffness including the static stability factor (SSF). The full factorial design of the experiment was used to analyze the results of the main effects on the tilt angle as evaluated by multibody dynamics simulation software. According to the results, the SSF of the passenger bus displayed higher sensitivity to the tilt angle than the suspension parameter at approximately 82%. The passenger bus with a low SSF tended toward rollover or low tilt stability more than one with a high SSF. For the suspension system, the anti-roll bar stiffness manifested a greater effect on the stability than the spring stiffness and damping coefficient, respectively. The results can be used to make design decisions and improve suspension parameters for improved vehicle stability.