Tyre-pavement contact stress patterns from the test tyres of the Gautrans heavy vehicle simulator (HVS) MK IV+

Abstract

This paper addresses the measurement (i.e. “fingerprinting”) of tyre loading and contact stress patterns associated with slow moving test tyres on the new Heavy Vehicle Simulator (HVS Mk IV+) of Gautrans. The two test tyres used on the HVS are a dual set of 12R22.5 and a single 315/80 R22.5 radial tyres, which represents typical tyres used on heavy vehicles (HV) in South Africa. The aim of this study was to quantify the three-dimensional tyre-road pavement contact stresses for these two types of truck tyres, which is currently employed for accelerated pavement testing (APT) in South Africa. Using the local Stress-In-Motion (SIM) technology, the measurements were done using a specially constructed concrete test facility at Gautrans Koedoespoort premises. A test matrix of five load levels and six inflation pressures was used on both HVS test tyres at creep speed conditions (<6km/hr). The results indicated that at constant inflation pressure the vertical tyre contactpattern (“fingerprint”) is highly non-uniform, and changes from the well known “n”-shape” to the “m-shape” with increased tyre loading. In addition the finger printing of the lateral and longitudinal stresses also appear to be highly non-uniform, but are relatively lower than the associated vertical stresses. In practice these load/stress data sets are crucial, firstly to understand the complex nature of forces within the tyre road contact patch, and secondly, to be used in the planning of loading/inflation pressure conditions for future HVS and APT testing. This is especially critical on roads incorporating thin asphalt surfacings especially during hot and also during wet climates. Finally, the results in this paper can be used to enhance future modeling of tyre-pavement loading in mechanistic-empirical (M-E) pavement design technologies.