Potential of functional image processing technique for the measurements of contact area and contact pressure of a radial ply tire in a soil bin testing facility

• Functional application of image processing technique for measurement of contact area is introduced.
• Contact pressure was assessed owing to its correlation with contact area in soil bin facility.
• Contact pressure was also measured by use of sufficient load cells in a housing at soil–tire interface.
• Measured and predicted values were compared to verify the potential of image processing obtained model.

The exploration principally deals with a promising applicability of image processing method for contact area determination. A digital camera mounted on a single-wheel tester was utilized to take images of contact area at four levels of tire inflation pressure (i.e. 70, 100, 140, and 175 kPa) and six levels of wheel load (i.e. 0.75, 1.75, 2.75, 3.75, 4.75, and 5.75 kN). Contact pressure measurements, subsequently, were performed utilizing seven embedded load cells incorporated in an instrumented housing in longitudinal and perpendicular direction of traversing. It was observed that contact area is a polynomial (with order of two) function of wheel load while there was a reverse linear relation between contact area and inflation pressure. Furthermore, contact pressure has linear relation with vertical load and inflation pressure. Models for contact area and contact pressure were developed by multiple regression analysis while a classical predicting model was assessed using contact area results of image processing technique. The models indicated acceptable coefficient of determinations amounts of 0.974 and 0.953 for contact area and contact pressure models, respectively. However, applied image processing method denoted R2-value of 0.988 for contact pressure equation.