A pressure-sinkage model for small-diameter wheels on compactive, deformable terrain

Traditional terramechanics theorems utilize pressure-sinkage models based on the assumption that the contact area between a tire and soil can be approximated as a flat plate. Examples include work by Bernstein–Goriatchkin, Bekker, Reece, and Ishigami. Recently, the authors have demonstrated that (1) this assumption does not hold for wheels with a diameter less than approximately 50 cm and (2) an improved diameter-dependent pressure-sinkage model can yield more accurate results. Further improvements to the pressure-sinkage model for small diameter wheels are presented here that account for both wheel width and diameter on compactive soils. Results from 125 pressure-sinkage tests using 35 wheel geometries on a clay/silt mix are presented. X-ray images of sub-surface soil deformation are used to visually validate the model.

► A key assumption of flat-plate pressure-sinkage models is highlighted. ► A review of previous diameter-dependent pressure-sinkage modeling is given. ► A dependence of the pressure-sinkage relationship on wheel width is determined. ► A modified pressure-sinkage model is proposed.