Rolling resistance of a vehicle plays an important role in the vehicle's fuel consumption. There are different mechanisms involved in the rolling resistance, namely, vehicle dynamics, tire bending and deformation, and tire tread deformation. Pavement surface profile is one of the factors that influences the rolling resistance and it can be divided into four scales of roughness, mega-, macro- and micro-texture. These scales influence different mechanisms of the rolling resistance. The micro-texture scale, which has the shortest wavelengths (less than 0.5 mm), despite being very important for friction and safety, has a negligible effect on the rolling resistance of the tire. The macro-texture scale, with wavelengths smaller 50 mm, mostly affects the tread deformation and tire bending mechanisms of rolling resistance. The mega-texture scale, which includes both wavelengths within and beyond the tire contact patch (between 50 and 500 mm), affects the vehicle dynamics and suspension system in addition to the tire deformation and bending. The roughness scale consists of any wavelengths larger than 500 mm and therefore mostly affects the deformation in the vehicle's suspension. The main aim of this study is to evaluate the effect of these scales on the vehicle's rolling resistance. For capturing the effect of the full surface profile on rolling resistance a model is required such that it is capable of evaluating all of the mechanisms involved in the rolling resistance. Such a model should include the tire as well as the suspension system of the vehicle. Here, for modeling the deformations within the tire, including tire bending and tread deformation, a full 3D finite element tire model is developed and verified. For investigating the energy dissipation in the vehicle suspension system, the tire model is combined with a quarter-car mechanical model, which is a simplified system of a spring and a dashpot in parallel. After decomposition of the surface profile into the above-mentioned scales, the root mean square or RMS is chosen as a common parameter for surface profile characterization to have a robust comparison of the effect of these scales. The effect of each scale of the profile on the rolling resistance is then evaluated separately using the developed models. For each scale, the effect of profile on the tire as well as the suspension is assessed. Then the effects of different scales are compared with each other. The macro-texture scale is found to mostly affect the tire deformations and have a negligible influence on the suspension system. The effect of mega-texture is found to be considerable, influencing the rolling resistance within the tire more than the vehicle's suspension. The roughness scale, however, affects the suspension system more than the tire. For low values of RMS, all of the scales, regardless of their wavelength, influence the rolling resistance similarly. However, for higher RMS values, the mega-texture shows a higher total rolling resistance than roughness. Although high values of RMS for mega-texture can be related to local events in the road profile, they can influence the rolling resistance noticeably.In addition, a good agreement is found between the developed model and the existing empirical studies for different scales. Moreover, the influences of vehicle operating conditions including applied load, driving velocity, tire temperature, and inflation pressure on the effect of surface profile on rolling resistance are investigated.
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