ABSTRACT

Pavements—an important part of worldwide infrastructure—are exposed to increasing traffic loads, new tire and vehicle concepts, and climate change. The future design of durable pavement structures requires a deep knowledge of the interactions in the coupled system of vehicle, tire, and pavement and the structural behavior of each subsystem. This paper includes recent research results in the field of tire and pavement modeling and their interaction. Furthermore, the concept for a holistic analysis of the coupled vehicle-tire-pavement system for the design of durable pavements is presented.

For a realistic and numerical efficient computation of tire-pavement interaction that considers rolling contact, both subsystems are modeled using the finite element (FE) method based on an arbitrary Lagrangian Eulerian (ALE) formulation that includes inelastic material descriptions. Additionally, thermo-mechanical effects are considered for the tire computation. The base of the structural FE-ALE pavement model is the realistic numerical description of the elastic, viscous, and plastic behavior of asphalt mixes.

Although initial results in the field of tire-pavement interaction were reached, much research has to be carried out to gain deeper knowledge of the coupled vehicle-tire-pavement system that includes detailed models of the subsystems and their interaction, as well as experimental investigations. The research group FOR 2089 will deal with this topic and will take the different length and timescales in particular into account.

ABSTRACT

This paper presents the design and development of a stationary microtexture road profiling system using the photometric stereo (PS) technique. The structure of the developed system is simple, mainly consisting of a digital single-lens reflex (DSLR) camera with a macro lens and multiple light-emitting diodes (LEDs). The camera with the lens is oriented perpendicularly to the pavement texture and takes images each with a different LED turned on at a time. With the pavement texture images with diverse shadings, the PS technique is applied by inverting the image-forming process locally (pixel-wise) to associate the measured image intensities with the known lighting directions to estimate the gradients for each pixel-corresponding surface patch of the pavement texture. Surface normal integration (SNI) is then employed to reconstruct the three-dimensional (3D) road surface in the microtexture scale. The PS-based system has several intrinsic advantages. First, it could achieve high accuracy for surfaces with most diffuse reflection. Second, the measurement speed is fast because of its area-scanning nature. Third, the spatial resolution is high because of the usage of a high-resolution complementary metal-oxide semiconductor DSLR camera. In addition, it can be less sensitive to effects from specularities and shadows compared with most optical-based methods, since images captured under diverse lighting directions in PS provide more cues for detection purposes. Last but not least, the hardware of the system can be made compact at low cost because of its simple structure and can be adapted for direct measurement on the pavement. Parametric studies for the Lambertian-based PS technique were first investigated analytically and numerically, and these investigations yielded the design of the system having eight LEDs with the same zenith angle of 30 degrees and uniformly distributed azimuth angles in 360 degrees. Several experimental results on various types of surfaces have demonstrated that the developed system could achieve the accuracy in the order of 10 microns.

ABSTRACT

Maintaining proper tire inflation is the number one issue facing commercial fleets today. Common, slow-leaking tread area punctures along with leaking valve stems and osmosis through the tire casing lead to tire underinflation with a subsequent loss in fuel economy, reduction in retreadability, tread wear loss, irregular wear, and increase in tire-related roadside service calls.

Commercial truck tires are the highest maintenance cost for fleets second only to fuel. This article will examine tire footprint analysis, rolling resistance data, and the effect on vehicle fuel economy from tires run at a variety of underinflated, overinflated, and recommended tire pressures. This analysis will also include the tire footprint impact by running tires on both fully loaded and unloaded trailers. The footprint analysis addresses both standard dual tires (295/75R22.5) along with the newer increasingly popular wide-base tire size 445/50R22.5.

ABSTRACT

Tires represent a crucial leverage for reducing CO₂ emissions: in the future, the importance of analyzing power losses under real-vehicle-driving conditions and conflicts between optimizing power loss, longitudinal dynamics, lateral dynamics, and comfort will increase.

The objective of the present study is to develop both the set of physical characteristic values (CV-set) and the genetic algorithm used to generate Magic Formula parameter sets that have the desired physical characteristics. To this purpose, improvements concerning the genetic algorithm are presented and a definition for the power loss of tires is derived and validated through measurements on an outer drum test bench. Then, four physical characteristic values describing the power loss are added to the existing CV-set. This CV-set, in combination with a genetic algorithm, allows us to generate virtual tires (e.g., Magic Formula model) with defined physical characteristics of longitudinal force, lateral force, aligning moment, and power loss.