“…To demonstrate the use of these results, a boundary model as described in 34 is used. The model uses FASTSIM algorithm to predict contact surface tractions.…”
Section: Methodsmentioning
confidence: 99%
“…26 Plasticity behaviour is calculated using Voce's hardening law 35 as is used in the study. 30 The model 34 uses an elliptical contact area and the parameters for limiting elastic (τ c1 ) and plastic (τ c2 ) shear stress are extended to incorporate temperature dependence, see equation (7). The model is simplified to assume that the coefficient of friction is independent of contact pressure.…”
Section: Mathematical Modelmentioning
confidence: 99%
“…The amounts applied for the model were selected based on the realistic friction values, as well as the assumption that SFM should in practice have less total consumption per distance applied. These parameters, as described in equation ( 7) and previous publication, 34 are summarized in Table 2. The temperature coefficients k 1 and k 2 have the same value due to a similar trend in the change of the limiting elastic and plastic coefficient of friction.…”
Top-of-rail product assessment in terms of frictional properties plays a key role in the evaluation of desired benefits for wheel-rail contact. In this study, a high-pressure torsion device is used to study the friction-displacement properties of three types of top-of-rail products. The effects of applied amount and increased temperature were investigated. All tested products were very sensitive to the amount applied. For the water-based substance, the evaporation of water created a solid-like film that provided very low friction. The increase in temperature lowered the coefficient of friction for dry contact but had a negligible effect on the applied products. A FASTSIM-based numerical model is used to demonstrate the application of these results.
“…To demonstrate the use of these results, a boundary model as described in 34 is used. The model uses FASTSIM algorithm to predict contact surface tractions.…”
Section: Methodsmentioning
confidence: 99%
“…26 Plasticity behaviour is calculated using Voce's hardening law 35 as is used in the study. 30 The model 34 uses an elliptical contact area and the parameters for limiting elastic (τ c1 ) and plastic (τ c2 ) shear stress are extended to incorporate temperature dependence, see equation (7). The model is simplified to assume that the coefficient of friction is independent of contact pressure.…”
Section: Mathematical Modelmentioning
confidence: 99%
“…The amounts applied for the model were selected based on the realistic friction values, as well as the assumption that SFM should in practice have less total consumption per distance applied. These parameters, as described in equation ( 7) and previous publication, 34 are summarized in Table 2. The temperature coefficients k 1 and k 2 have the same value due to a similar trend in the change of the limiting elastic and plastic coefficient of friction.…”
Top-of-rail product assessment in terms of frictional properties plays a key role in the evaluation of desired benefits for wheel-rail contact. In this study, a high-pressure torsion device is used to study the friction-displacement properties of three types of top-of-rail products. The effects of applied amount and increased temperature were investigated. All tested products were very sensitive to the amount applied. For the water-based substance, the evaporation of water created a solid-like film that provided very low friction. The increase in temperature lowered the coefficient of friction for dry contact but had a negligible effect on the applied products. A FASTSIM-based numerical model is used to demonstrate the application of these results.
“…Current wheel-rail adhesion models will be explored in the next sub-section.Figure 6.wheel-rail adhesion under water. 126 …”
Section: Wheel-rail Frictionmentioning
confidence: 99%
“…137 Ohyama 125 and Chen et al 139 are the scholars who earlier introduced the hydrodynamic lubrication theory 140 to study the adhesion problem with water in the wheel-rail interface. To reduce computation duration, EHL empirical equations 125,126,141 are employed to determine the adhesion coefficient directly in consideration of rough surfaces using the viscosity of water reported by Bett and Cappi. 142 Chen and her coworkers also 127 proposed an improved 3D numerical model using partial EHL theory at 3D contact to estimate the adhesion coefficient between wheel and rail by considering the surface roughness amplitude and roughness orientation parameters.…”
Rail transportation is regarded as a reliable, quick, and secure mode of transportation. The wheel-rail contact interaction is crucial to the railway operation since it is responsible for supporting, traction, braking, and steering of railway vehicles. Improper wheel-rail interactions may produce or exacerbate wheel-rail interface issues such as rolling contact fatigue (RCF) and wear, which can threaten the vehicle’s running safety and stability. A review of the evolution and recent literature on wheel-rail contact mechanics and tribology is presented here. Topics covered include the basics of wheel-rail contact problem and methodologies for modeling both the normal contact (Hertzian and non-Hertzian) and tangential contact (Kalker’s theories including CONTACT and FASTSIM algorithms, Polach’s theory, USETAB program, etc.). The paper also reviewed various effects of contaminants and environmental conditions (water, leaves, sand, temperature, humidity, etc.) in wheel-rail contact. Various wheel-rail empirical adhesion models like the Water-induced low adhesion creep force model (WILAC) model and adhesion models based on elastohydrodynamic lubrication (EHL) theory (Greenwood-Tripp [GT] and Greenwood-Williamson [GW] models) are also reviewed. Lastly, the paper discusses the need and challenges for developing and integrating the wheel-rail non-Hertz contact model and adhesion model, as well as open areas for further research.
Wheel‐rail adhesion is important to the traction and braking of railway vehicles. This paper develops a three‐dimensional numerical model considering surface roughness and temperature to investigate water‐contaminated adhesion characteristics. A simplified elastohydrodynamic lubrication model considering the thermal effect is developed to obtain the normal load carried by liquid film and asperities. Meanwhile, a third body layer (3BL) model, which considers the effects of pressure and temperature on 3BL, is used to calculate the tangential stress and friction coefficient of asperity contact. To verify the numerical model, firstly, the results are compared with the existing experimental results at low and high speeds. In addition, the effects of surface roughness and temperature on adhesion coefficient are investigated. Furthermore, the elastoplastic behaviour of the tangential stress and the adhesion characteristics for large creepages are studied. The obtained adhesion‐creepage curve can represent the decreasing trend after reaching saturation because of temperature.
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