Measuring Lateral Tire Performance on Winter Surfaces

The Army has approved and funded an Army Technology Objective (ATO) entitled High Fidelity Ground Platform and Terrain Mechanic Modeling. This ATO is being jointly performed by the Engineer Research and Development Center (ERDC) along with the U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC) and the Army Research Laboratory (ARL). Two of the ERDC laboratories are participating in the ATO: The Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH, and the Geotechnical and Structures Laboratory in Vicksburg, MS. One of CRREL's major milestones for the ATO is to extend two-dimensional ground contact models for the TARDEC Real-time Simulator to full three-dimensional functionality by including the lateral forces. Central to that requirement is an understanding of lateral forces on all-seasons terrain. While modeling of vehicle tire lateral force interactions for typical hard paved surfaces is well understood, there is a need to translate that understanding in a consistent manner into off-road terrain and low-friction surfaces. The experimental work described in this paper is fundamental to gaining the required understanding. The experimental work, performed with instrumented vehicles, was accomplished via a contract with the Nevada Automotive Test Center. The testing included both lateral and longitudinal traction tests on winter surfaces. The surfaces included ice, packed snow, and disaggregated snow. The two principal tires tested were an all-season LT235/75R15 that has been the subject of many tests on the CRREL instrumented vehicle, and a tire used on the military's HMMWV, size 37 x 12.50R16.5. For each tire and surface, tests at a minimum of two inflation pressures were conducted. For each surface/tire/inflation variant a minimum of ten replicate data sets were obtained. This paper reports the results of the tests and the analysis conducted to date.