Numerical analysis of three-dimensional thermo-elastic rolling contact under steady-state conditions

In this study, a three-dimensional thermo-elastic model that considers the interaction of mechanical and thermal deformation is developed using a semi-analytic method for steady-state rolling contact. Creepage types in all directions are considered in this model. For verification, the numerical analysis results of shear traction and temperature increase are compared separately with existing numerical results, and the consistency is confirmed. The analysis results include heat flux, temperature increase, contact pressure, and shear traction. Under severe rolling conditions, the thermal effect changes the behavior of the contact interface significantly. Furthermore, the effects of creepage, rolling speed, and conformity under different rolling and creep conditions are investigated.

The Analysis of Stone Trapping in Tire Tread for Various Road Conditions

A tire tends to trap stones in its tread pattern when the vehicle is on a move and this might affects the tire balance due to uneven tread wear of tread portion. The study aims to simulate stone trapping performance under various tire tread patterns and road conditions as well as assessing the performance of tires with stones trapped. The stone trapping phenomena on different tire tread pattern were analyzed under dry and wet road conditions. The tire models chosen were the symmetrical tire, asymmetrical tire, and directional tire. The model of these tires, stone and a flat road surface were created using SolidWorks and Fusion360 software and the static structural simulation is performed by using finite element analysis method. Tire inflation analysis and steady state rolling analysis were conducted to evaluate three parameters: total deformation, Von-Mises stress and equivalent elastic strain of the tires. It found that all three parameters are higher when stone trapped in tire for all tread pattern types. Symmetrical tread pattern provides the least wear and tear since it has the lowest increment of maximum equivalent elastic strain in both road conditions. Stone trapping in tire grooves would impact on the lifespan of the tire.

Modeling of Surface Drainage during the Service Life of Asphalt Pavements Showing Long-Term Rutting: A Modular Hydromechanical Approach

This paper presents a modular hydromechanical approach to assess the short- and long-term surface drainage behavior of arbitrarily deformable asphalt pavements. The modular approach consists of three steps. In the first step, the experimental characterization of the thermomechanical asphalt material behavior is performed. In the second step, information about the long-term material behavior of the asphalt mixtures is integrated on the structural scale via a finite element (FE) tire-pavement model for steady-state rolling conditions and time homogenization in order to achieve a computationally efficient long-term prediction of inelastic deformations of the pavement surface (rut formation). In the third step, information regarding the current pavement geometry (deformed pavement surface) is used to carry out a surface drainage analysis to predict, e.g., the thickness of the water film or the water depth in the pavement ruts as a function of several influencing quantities. For chosen numerical examples, the influence of road geometry (cross and longitudinal slope), road surface (mean texture depth and state of rut deformation), and rainfall properties (rain intensity and duration) on the pavement surface drainage capacity is assessed. These parameters are strongly interrelated, and general statements are not easy to find. Certain trends, however, have been identified and are discussed.

The transient response of high-speed wheel/rail rolling contact on “roaring rails” corrugation

A high-speed wheel/rail finite element model is developed to focus on the non-steady-state rolling contact. The wheel/rail contact is solved based on the surface-to-surface contact algorithm, and the explicit finite element method is used to simulate the dynamic high-speed wheel/rail rolling contact. Considering the track–vehicle coupling system dynamics and the wheel/rail geometric nonlinearities, the wheel/rail contact on the short wave rail corrugation under the high-frequency vibration and the influence of train passing frequency on the track–vehicle system dynamics are studied. The explicit finite element method can be used to simulate the non-steady-state rolling contact process of the high-speed wheel/rail. After the initial load condition, the wheel/rail contact state tends to be stable in a short period of time. The short wave corrugation causes the high-frequency vibration of the track–vehicle system; the slightly advanced phase of the wheel/rail contact force promotes the development of rail corrugation in the rolling direction. When the train passing frequency is close to the rail pinned–pinned frequency, the pinned–pinned resonance occurs. The overall vibration near the fastening is relatively large and accelerates the damage of components. The longitudinal force is clearly affected by the traction torque with a periodic wheel/rail stick-slip vibration. The pinned–pinned resonance will promote the sliding wear at the wave trough near the fastening and it will become severe with the increase of the traction.

Analysis of steady-state frictional rolling contact problems in Schapery–nonlinear viscoelasticity

In the context of an updated Lagrangian formulation, a computational model is developed for analyzing the steady-state frictional rolling contact problems in nonlinear viscoelastic solids. Schapery's nonlinear viscoelastic model is adopted to simulate the viscoelastic behavior. In addition to the material nonlinearity, the model accounts for geometrical nonlinearities, large displacements, and rotations with small strains. To satisfy the steady-state rolling contact condition, a spatially dependent incremental form of the viscoelastic constitutive equations is derived. Consequently, the dependence on the past history of the strain rate in the stress–strain law is expressed in terms of the spatial variation of the strain. The contact conditions are exactly satisfied by employing the Lagrange multiplier approach to enforce the contact constraints. The classical Coulomb's friction law is used to simulate friction. The developed model is verified and compared and good agreement is obtained. The applicability of the developed model is demonstrated by analyzing the steady-state rolling contact response of viscoelastically walled-wheel over rigid foundation. Moreover, the obtained results show remarkable effects of the rotational velocity and the viscoelastic material parameters on the mechanical response of steady-state frictional rolling contact.

Finite Element Based Analysis of Reinforcing Cords in Rolling Tires: Influence of Mechanical and Thermal Cord Properties on Tire Response

ABSTRACT Tires of passenger cars and other special tires are made of rubber compounds and reinforcing cords of different type to form a composite with distinct mechanical and thermal properties. One of the major load cases is the steady state rolling operation during the tire's service. In this contribution, attention is paid to the strain and force state as well as the temperature distribution in the carcass cord layer of a steady state rolling tire. A simple benchmark tire geometry is considered, which is made of one rubber compound, one carcass cord layer (textile), and two belt cord layers (steel). From the given geometry, two tire designs are derived by using two distinct types of reinforcing cords (polyester and rayon) for the carcass cord layer. Subsequently, the two tire designs are subjected to three load cases with different inner pressure, vertical force, and translational velocity. The strain and the force state as well as the temperature distribution in the cords are computed via a thermomechanically coupled finite element simulation approach for each tire design and load case. To realistically capture the thermomechanical behavior of the cords, a temperature- and deformation-dependent nonlinear elastic cord model is proposed. The cord model parameters can be directly derived from data of cord tensile tests at different temperatures. Finally, cord design parameters (minimum and maximum strains and forces in the cords, maximum strain and force range per cycle, and maximum cord temperature) are summarized and compared. Additionally, the global vertical stiffness and the rolling resistance for each tire design are addressed.