Analysis and testing of the steady-state turning of multiaxle trucks
Authors: C. B. Winkler, John Aurell
The International Standards Organization (ISO) is currently involved in an effort to develop a standard test procedure for evaluating the steady-state turning behavior of heavy vehicles. In the course of developing this standard, a new analysis has evolved which expands the basic understanding of the steady-state turning of all motor vehicles.
The established, simplified analyses of steady-state turning are based on a simple vehicle model in which lateral acceleration is the only motion variable that affects tire slip angles. The new analysis examines a more complex vehicle whose slip angles depend on lateral acceleration plus another motion variable. Basic differences in the steady-state turning behavior of simple and complex vehicles are explained using the handling diagram. It is shown that the complex vehicle can be represented as a simple vehicle with an equivalent wheelbase. Trucks with multiple, nonsteering rear axles are one example of the complex vehicle. An analysis specific to such trucks is presented as is a physical interpretation of the equivalent wheelbase of trucks. Results from simulated and actual track tests which confirm this analysis are presented.