Experimental investigation of dynamic forces of driven and driving off-road tires traversing rigid obstacles with different shapes

The main objectives of this study is to determine the dynamic impact force imparted on a lugged tire due to vertical load, travel speed of the tire, shape and height of the obstacles, and slippage of tire. The tests have been carried out by means of a soil bin facility. Three shapes of triangular, trapezoidal and curved obstacles were used in the study each at three heights of 2, 3 and 4 cm while two wheel load levels of 1 and 2 kN were considered. These results show that by increasing vertical pre-load on the tire, the total dynamic impact force is increased. This increase could be attributed to dependence of vertical inertial forces to the dead load of the wheel axle. The result of analysis shows linear relation between the tire travel speed and total dynamic force. At constant obstacle shape and height, as travel speed increases, the impact force imparted to tire increases. The dynamic force generated in vertical and horizontal directions have shown significant differences. In the other words, increasing height of obstacles result in the increase of vertical component of tire velocity and then increasing momentum of tire which led to enhancement of vertical force.