Analysis the dynamic rollover threshold and roll safety thresholds of 4-axle truck vehicle: a simulation approach

The purpose of this article is to determine the Dynamic Rollover Threshold (DRT) and Roll Safety Thresholds (RSTs) of 4-axle truck vehicle when turning maneuvers. A 30-degree-of-freedom (DOF) dynamic model of 4-axle truck vehicles is built based on the Newton–Euler equation systems and the Multibody System analysis method. 6 DOFs are used to characterize the motion of the vehicle body. 2 DOFs are used to characterize the roll motion of the front and rear masses of the vehicle’s body. This considers the impact of the vehicle frame’s torsional stiffness on the vehicle’s dynamics. 2 DOFs are used to characterize the motion of the 2 rigid beams of the “Walking Beam” suspension system. The road steering wheel steer angles are calculated from the steering wheel angle while ignoring the elasticity of the steering system. The Burckhardt tire model calculates the tire forces that interact between the tires and the road. The simulation is conducted using MATLAB-Simulink software, with a vehicle speed range from 20 to 90 km/h and an amplitude of steering wheel angle range from 12.5 degrees to 350 degrees. 3D data of the maximum of Load Transfer Ratio (LTR_max), and the maximum of lateral acceleration of the vehicle body (a_ymax) are generated from the simulation cases. From these 3D data and the proposed LTR values (LTR_prop), the DRT, the Safety Roll zones, and the RSTs of the lateral acceleration are determined. For LTR_prop of 1, the DRT ranges from 4.633 to 4.920 m/s². For LTR_prop of 0.9, the RST ranges from 4.384 to 4.570 m/s². For LTR_prop of 0.75, the RST is between 4.011 and 4.254 m/s². And for LTR_prop of 0.6, the RST is between 3.396 and 3.454 m/s². These DRT and RSTs can be used as the basis for designing warning and anti-roll control systems of multi-axle truck vehicle.