Santosh Kumar Srirangam

Development of a thermomechanical tyre–pavement interaction model

Tyre operating temperature is an important concern for both tyre manufacturers and highway agencies which is known to have a major influence on the tyre traction. Most of the past tyre–pavement interaction studies were focused on the performance of the tyre while giving limited importance to the effect of the pavement texture profile. This paper presents a methodology of coupled thermomechanical finite element (FE) model to determine the progressive temperature development in tyre cross section. The model is developed for a test tyre rolling over an FE mesh of an asphalt pavement surface, and the effect of the developed temperature on the hysteretic friction is evaluated. Such a model will enable tyre manufacturers to come up with optimised tyre design; on the other hand, road agencies can design their friction test protocol. In this study, an attempt has been made to examine the developed tyre–temperature in time at different regions of tyre.

Influence of Temperature on Tire–Pavement Friction: Analyses

Past experimental studies show that tire–pavement friction values are related to conditions surrounding the tire such as pavement temperature, ambient temperature, contained air temperature, and surface characteristics of the pavement. For measurements taken in different temperature conditions, road agencies generally apply correction factors. These correction factors are based primarily on experience and previous field test measurements that have very limited transferability under different conditions. This paper studies frictional behavior of test tires under different surrounding temperature conditions using finite element analysis. The scope of this research is to analyze the effect of pavement temperature, ambient temperature, and contained air temperature on frictional measurements. Finite element analysis of fully and partially skidding tires over different asphalt pavement surfaces, namely, porous asphalt, ultrathin surface, and stone mastic asphalt, is considered. Observation showed that a higher pavement temperature, ambient temperature, and contained air temperature resulted in a lower hysteretic friction for a given pavement surface and a given tire slip ratio. In contrast, a lower tire slip ratio and a pavement with higher macrotexture resulted in higher friction. This study highlights that a critical combination of these factors will decrease friction significantly.

Safety Aspects of Wet Asphalt Pavement Surfaces Through Field and Numerical Modeling Investigations

Good pavement macrotexture has a direct influence on vehicle safety during wet weather conditions by improving vehicle traction and braking ability. Apart from the macrotexture, several other factors, such as environmental, tire, and pavement-related characteristics, affect the wet friction. Most experimental studies had a limited scope of reusability as soon as there was a change in any of the other factors. In recent years, the development of powerful finite element tools has made it possible to simulate complex wet tire–pavement interaction as close as possible to the actual field conditions. However, to the best of the authors’ knowledge, none of the past analytical and numerical studies were able to include the actual pavement surface texture in their analysis. This paper describes an approach to study the effect of actual surface morphologies of asphalt pavements on the wet friction coefficient by using the finite element method. Asphalt surface morphologies representative of open-graded mix to close-graded mix were used in the finite element analysis. The finite element model was duly calibrated with the field investigations conducted with state-of-the-art field equipment. The extreme loss of wet friction, which ultimately led to the risk of hydroplaning, was also studied. The analyses were performed for two water film thicknesses, two tread patterns, and two tire slip ratios. The results from the current study can be used as safety indicators of in-service asphalt pavements under wet and flooded conditions.

Study of Influence of Operating Parameters on Braking Friction and Rolling Resistance

Tire–road interaction addresses safety with respect to braking friction and energy efficiency in the context of rolling resistance. These phenomena are coherent, but their engineering solutions can be contradictory. For example, highly skid-resistant surfaces may not be ideal for fuel economy, but surfaces with low rolling resistance may be prone to skidding. Several experimental and numerical studies have investigated the individual phenomena, but insufficient attention has been paid to studying them coherently. The present study computed braking friction and rolling resistance for various operating parameters and their coherent response for each parameter with the use of a thermomechanical contact algorithm. Micromechanical finite element simulations of a rolling or braking pneumatic tire against selected asphalt concrete surfaces were performed for various operating conditions, such as tire load, inflation pressure, speed, and ambient air and pavement temperatures. The coefficients of braking friction and rolling resistance were found to decrease with the inflation pressure and the temperature and to increase with the wheel load. The braking friction coefficient was found to decrease with the speed, in contrast to the rolling resistance coefficient, which increases with the same parameter. A full-skidding tire registered lower braking friction than a 20% slipping tire. Also, an asphalt surface with higher macrotexture offered higher braking friction and higher rolling resistance, and vice versa.

Study of Cornering Maneuvers of a Pneumatic Tire on Asphalt Pavement Surfaces Using the Finite Element Method

Field experience shows that most road accidents that occur during turning maneuvers are caused by the loss of vehicle control. The loss of vehicle control is often related to a lack of sufficient friction between the tire and the pavement surface. In experiments and analytical studies, the overall antiskidding performance of a pneumatic tire has been observed to be affected by operating conditions, road texture, and surrounding temperatures. Interactions of these parameters create a complex relationship between their combined effect and the tires ability to combat skidding. One way to analyze the cornering maneuvers of a vehicle is by means of a validated finite element tool that can carry both the tire and the pavement properties. Few computational studies have been conducted to study the cornering performance of a rolling pneumatic tire, and none of these studies included the role of pavement surface morphologies in their analysis. In this study, a thermomechanical framework was used to analyze the influence of temperature on cornering friction. The cornering friction coefficient was found to decrease with an increase in the loads and the speeds. The cornering friction coefficient was found to increase with an increase in inflation pressure, sideslip angle, and pavement surface texture depth. The proposed study contributes to an understanding of the cornering performance of passenger car tires.

Hydroplaning of Rolling Tires under Different Operating Conditions

In the present study, a three dimensional hydroplaning model was developed to quantify the hydroplaning speed at different operating conditions of tire under flooded pavement conditions. The hydroplaning speed was simulated for no slip and partial slip cases of tire. The hydroplaning speed was also computed for different yaw angles for rolling cases. Loss of braking traction due to hydroplaning is characterized by computing longitudinal friction force with respect to a variety of slip speeds up to hydroplaning. Impending hydroplaning risk on directional stability of vehicle was studied by plotting the cornering force against a range of rolling speeds up to hydroplaning. The fluid-structure-interaction was performed by means of the Coupled Eulerian Lagrangian approach in the finite element context. The proposed model provides insight on the influence of hydroplaning conditions on braking and steering efficiency of a vehicle.

Evaluation of Structural Performance of Poroelastic Road Surfacing Pavement Subjected to Rolling–Truck Tire Loads

Road traffic is a major source of noise pollution. Road authorities and pavement researchers have been trying to reduce this noise pollution by laying quieter pavement surfaces. Poroelastic road surfaces (PERS) have been found to be the most effective solution because they are very porous and elastic in nature compared with conventional dense asphalt surfaces. However, the structural performance of PERS pavement under heavy traffic loads is still unknown. The aim of this study was to determine the critical stresses experienced by PERS pavement under heavy loads applied by a wide-base truck tire. For this purpose, finite element (FE) simulations of a wide-base truck tire rolling over a PERS pavement system were performed for various material properties of PERS and adhesive layers, speeds, tire loads, and inflation pressures. From the FE model results, the critical stress envelopes were constructed by using the concept of stress invariants. Stress invariants represent normal and shear stresses that might cause the PERS layer to fail under the critical combination of material, loading, and operating variables and therefore act as design indicators. The FE results showed that the higher contact pressures and the lower material stiffness resulted in higher stress invariants. It was also determined that the stiffness of the adhesive layer influenced the response of the PERS layer. The current study demonstrated a robust methodology for assessing the performance of a thin PERS layer pavement system under rolling–truck tire operating conditions.

A Durability Analysis of Super-Quiet Pavement Structures

Poro Elastic Road Surfacings (PERS) as a substitute for conventional noise barriers or other traditional pavement surfacings like open graded mixes are currently attracting significant attention. Ascertaining the durability of PERS material itself and its bonding with the underlying pavement layer against high traffic and high load intensities is of primary importance. In this contribution, results are presented of nonlinear finite element simulations of a high volume pavement profile comprised of a PERS top layer bonded to a conventional open asphalt top layer. Traffic loading was applied by means of a simulated truck tire moving load for various operating conditions. The paper focuses on investigation of the influence on the structural pavement response of various loading conditions and material properties of PERS and adhesive layer. The study concludes with guidelines for the optimum combination of design parameters that lead to increased durability of pavements constructed with a PERS top layer.