Estimation of LTR rollover index for a high-sided tractor semitrailer vehicle under extreme crosswind conditions through dynamic simulation

Lateral load transfer ratio (LTR) is a criterion that is often used for designing ground vehicle rollover warning technologies to indicate the vehicles rollover status. Generally, LTR index depends on road geometry and vehicle characteristics. However, crosswind loads have the potential to influence the roll stability and therefore the safety of road vehicles particularly large commercial units. This study provides improved methodology for the computation of the LTR index for a high-sided tractor semitrailer vehicle under crosswind conditions. For this purpose, since experiments on real vehicles for active safety technology are difficult to carry out, a coupled simulation of transient crosswind aerodynamics and multi-body vehicle dynamics has been proposed. Based on CFD method, a large-eddy simulation (LES) technique was employed to predict the transient crosswind aerodynamic forces. Then, the predicted aerodynamic forces were input into multi-body dynamic simulations of the tractor semi-trailer vehicle that were performed through ADAMS/Car software. Simulation results show that comparing to the traditional LTR index, the LTR under crosswind is more efficient to detect manoeuvre-induced rollovers. This trailer rollover indicator that has been improved by the proposed methodology can provide more reliable information to the warning or control system in the presence of wind conditions.