Abstract

A technique for measuring the dynamic three-dimensional contact profile between a tyre and deformable soil has been developed. The method involves measuring incremental lateral arc lengths of the profile at discrete locations along the contact length and fitting the coefficients of a model of soil deformation at the soil-tyre interface to the experimental data using a nonlinear constrained optimization algorithm (SUMT). Two representations of the measured contact area were compared: (i) the two-dimensional surface which is the union of all points on the original undeformed soil surface which undergo deformation by the tyre; (ii) the final three-dimensional deformed surface. Contact area measurements were made for two different sized tyres at two levels of inflation pressure, dynamic load and slip in two different soil conditions. The contact width, length and area predicted by the technique were compared with corresponding values for static contact between a tyre and a rigid surface.