APPROXIMATION AND ANALYSIS OF TIRE/PAVEMENT CONTACT INFORMATION RESULTING FROM ROAD SURFACE ROUGHNESS (FORCE, ENVELOPMENT, SAFETY, NOISE)

Road surface texture influences tire noise, skid resistance, vehicle performance, and rolling resistance. The effect of surface texture in tire/pavement interaction is investigated by approximating the contact pressure, contact length, and depth of penetration created by surface roughness in the tire/pavement contact region.; An approximation method is developed to predict the vertical contact stress or pressure produced by a rigid indentor contacting an elastic half-plane using elasticity theory and a spline approximation of the pressure. Only discrete samples of the deformed half-plane or contact surface are required as input information into the method. The methodology is validated by comparing approximated, analytic, and finite element contact results using symmetrical, nonsymmetrical, and multiple indentors.; The approximation method is applied to tire/pavement interaction by requiring only road surface profile data and tire inflation pressure to be the input information. An algorithm is developed for predicting a 2-D contact pressure profile associated with a 2-D surface profile. Information of individual contact pressures and lengths are contained in the pressure profiles. The depth of penetration and an approximated deformed tire geometry are also generated when the approximated pressure profile is equated to an equilibrium pressure.; The spectral energy contained in the pressure profiles is correlated with tire noise spectral energy and pavement skid resistance to examine the tradeoffs between pavement skid resistance and noise reduction. The correlation results show that an increase in texture-induced pressure energy in the frequency range below 1250 Hz increases tire noise, and an increase in pressure spectral energy at frequencies above 1250 Hz has no effect or reduces tire noise. The entire pressure frequency range is positively related to pavement skid resistance. The correlation results imply that tire noise is reduced or unaffected and pavement skid resistance is improved by increasing the spectral energy contained in the texture-induced contact pressure at frequencies above 1250 Hz at normal highway speeds.