Dynamic roll instability analysis of heavy vehicles using energy approach

In this paper, roll plane models of heavy vehicles are proposed to study th eir dynamic rollover properties. Equations of motions are derived using an energy approach. These equations are considered valid until the vehicle app roaches its tip-over position. Dynamic rollover indicators in terms of Roll over Prevention Energy Reserve Factor (RPERF) and Critical Distance Ratio ( CDR) are discussed. Dynamic rollover limits of a straight truck subject to different evasive manoeuvres are investigated using the proposed energy app roach and the indicators. The dynamic rollover limits predicted by RPERF ar e slightly smaller than those predicted by CDR. It is concluded that the dy namic rollover limit of a vehicle is manoeuvre dependent, and the rollover limits at relatively high steering frequencies are considerably larger than the corresponding static rollover threshold of the vehicle. The dynamic ro llover limits of the vehicle approaches the SRT from the upper side as the excitation frequency decreases. The SRT thus provides an underestimate of t he anti-roll ability of the heavy vehicles under transient steering manoeuv res.