Prediction of sinkage and rolling resistance for off-the-road vehicles considering penetration velocity

The use of plate pressure tests is common for the prediction of sinkage and rolling resistance for off-the-road vehicles. Most of these penetration tests are carried out with small penetration bodies in a quasi-static way. However, when vehicles are rolling on soft soil, the soil is charged dynamically. Consequently, this dynamic effect should be considered by the prediction of sinkage and rolling resistance. At the Institute of Automotive Engineering at Hamburg, tests were carried out with penetration bodies in sizes up to 900 cm², which is comparable to the contact area of wheels. The results confirm the influence of the penetration velocity. With a constant load, the body sinkage is smaller at a higher penetration velocity. Also shear tests with shear rings of different sizes have been carried out and an exponential equation for the shear strength, not depending on the shear ring size, was found. A dynamic pressure-sinkage relationship depending on the penetration velocity or driving speed was derived and transferred to the sinkage and rolling resistance of a rigid wheel.