3-DIRECTIONAL CONTACT STRESS DISTRIBUTIONS FOR A PNEUMATIC TRACTOR TIRE IN SOFT SOIL

Three-directional contact stresses were investigated at three location s on a lug of a pneumatic tractor tire in a completely soft rotary-til led soil overlying a hardpan about 250 mm below the surface. The 12.4R 28 pneumatic tractor drive tire was operated at two dynamic loads and two inflation pressures at 20% slip. Three transducers were embedded i n the lug face near the tire centerline, approximately the center of t he lug, and near the outside edge of the lug. The general trend of str ess distributions reflected the effect of tire inflation pressure more than dynamic load in this experiment. Increased dynamic load increase d the levels of stresses. The maximum normal stress occurred near the tire centerline at high inflation pressure. The maximum tangential str ess occurred near the tire centerline and decreased as the position mo ved from the tire centerline to the edge of the tire. At the high infl ation pressure, the maximum lateral stress was concentrated near the b ottom center position for each transducer.