Geometric and Normal Contact Stress Analysis of a Rolling Tire Footprint

An optical method based on white light refraction and reflection is described for the measurement of normal contact stress between “soft” structures and a rigid transparent surface. The objective is to provide information on the background of the method used and on the practical aspects of the application of the method to the experimental tire analysis. The method used allows visualization of tire contact patch geometry as well as of the normal stress distribution in the contact. Experimental setup, calibration, data collection, and data analyses are presented. Footprint contact analysis of static and rolling tires are illustrated on several examples.