Tyre lateral slip effect on off-tracking of a long combination vehicle

Abstract

This paper evaluates the effect of tyre lateral slip on the off-tracking of a long combination vehicle (LCV) consisting of a semi-truck with 28-ft double trailers. A geometric model of LCV motion neglecting tyre slip and a high-order multi-body dynamic model in TruckSim® including tyre slip are developed and validated against other simulation and field test data. Tyre slip effect on off-tracking is measured by comparing the models' estimated off-tracking when the LCV netogiates 50, 75 and 100 ft (15.24, 22.86, and 30.48 m) radius curves at speeds of 1–16mph (1.6–25 km/hr). Two trailer payloads – 6000 lb/trailer and 14,500 lb/trailer – and three tyre-road friction coefficients – 0.85, 0.45 and 0.65 – were simulated. The simulation results indicate that tyre lateral slip increases – and thus off-tracking decreases – approximately to the second-order of vehicle speed for a given curve radius. It is also found that tyre lateral slip is negligible for speeds below 3–4mph (5–6 km/hr) in all simulated conditions. Additionally, as the path radius increases, tyre lateral slip and vehicle off-tracking sensitivity to vehicle speed reduce. The results suggest that for moderate speeds (>7mph (11 km/hr)), increasing vehicle payload and reducing surface friction coefficient result in an increase in tyre lateral slip that consequently reduces off-tracking.