Multiscale Finite Element Modeling of Wheel–Rail Rough Normal Contact Measurements Using Pressure Measurement Film

Lekue, Jagoba; Dörner, Florian; Schindler, Christian

doi:10.1080/10402004.2018.1460433

Cited by 5 publications

(8 citation statements)

References 13 publications

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“…Additionally, the impact of roughness on the measured contact area was simulated. As already demonstrated, the increase in nominal contact area due to roughness, which is indeed detected by HS films, can be reproduced with great precision within the load range considered here if an appropriate interaction characteristic is defined [27]. The hard contact interaction between film and wheel was replaced accordingly by an experimentally obtained pressureoverclosure law that incorporates microscopic asperity interaction between film and roughened steel with an approximate roughness arithmetic average of Ra & 1.5 lm.…”

Section: Wheel-rail Contactmentioning

confidence: 66%

“…Alternatively, a conventional material model can be assigned to the elements by defining a constitutive law [31], as done in this work. The finite element model employed so far to replicate the Hertzian experiments conducted in the laboratory [26,27] was accordingly adapted for the material calibration procedure as depicted in Fig. 1.…”

Section: Film Model Calibrationmentioning

confidence: 99%

“…By generating detailed finite element models of the Hertzian experiments including the film, a relation between measurement error and capsule size (and thus film type) could be established [26]. Furthermore, microscopic roughness was implemented in the macroscopic models of the experiments in order to demonstrate that the lack of sensitivity of HHS films to roughness variations is perfectly consistent with the governing contact mechanics [27]. Said studies considered the plastic nature of PET by defining linear Drucker-Prager material behavior [28], which was originally conceived for soil materials but has found wide use in polymer modelling as it considers their characteristic dependence of yield stress on hydrostatic pressure [29].…”

Section: Introductionmentioning

confidence: 99%

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Calibration of a finite element model of Prescale film for wheel-rail normal contact area measurements

2021

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This article presents the latest of a series of research activities aimed to determine the deviation originated when Prescale pressure measurement film is used to measure the size and shape of the wheel-rail contact area. Despite being an attractive solution due to the simplicity of the measurement procedure, it is well known that the contact interaction is altered by the presence of the film. Consequently, characterizing and filtering out the systematic measurement error is a fundamental requirement for accurate quantitative assessments. Nevertheless, the complexity of the wheel-rail contact problem, which lacks an analytical solution, hinders the direct determination of correction values. The approach presented here builds on error corrections for simpler Hertzian geometries to calibrate a film model for further use in the wheel-rail contact scenario. The results highlight the marked dependency of the measurement error on wheel and rail roughness and underline the importance of including the film into finite element models that are validated by comparison with experimental observations.

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Section: Wheel-rail Contactmentioning

confidence: 66%

Section: Film Model Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calibration of a finite element model of Prescale film for wheel-rail normal contact area measurements

2021

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“…It was originally developed to calculate soil. 73 Such a model was utilized by Lekue et al 74 to simulate rough surfaces of Hertzian bodies. 74 They identified a correction factor for the three measurement films used.…”

Section: Comparison Of Pressure Measurement Film With Fea And/ or Hertzmentioning

confidence: 99%

“…73 Such a model was utilized by Lekue et al 74 to simulate rough surfaces of Hertzian bodies. 74 They identified a correction factor for the three measurement films used. However, these factors were only valid for smooth surfaces, because the measurement error increased with a higher surface roughness.…”

Section: Comparison Of Pressure Measurement Film With Fea And/ or Hertzmentioning

confidence: 99%

Overview of methods to identify the static normal wheel-rail contact

Stratmann

Goersch

Schindler

2021

Proceedings of the Institution of Mechanical Engineers, Part F:

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Determining the shape and size of a wheel-rail contact area is required to calculate fatigue and wear of wheel and rail. Fatigue and wear are influenced by high pressures of up to 1000 MPa that act on the small contact area of approximately 1 cm². One problem in identifying the contact patch is the inaccessibility of the contact point. Therefore, numerical and experimental methods have been applied to identify the shape and size of the contact area in the static wheel-rail contact. Here, we summarize and compare methods to identify the static wheel-rail contact area, in particular the Hertzian calculation, the use of carbon paper, the use of pressure measurement film, the finite element method, the use of ultrasonic testing, and a semi-Hertzian method called STRIPES. Our review revealed that several methods exist to determine the static wheel-rail contact, which were introduced as well as results of some research projects. However, the partly incomplete description of methods studied impeded a detailed assessment of the results. Furthermore, due to the non-comparable parameters applied in the different studies, it was impossible to contrast the results and methods presented in the different publications. Hence, it is recommended that future results in the field of static wheel-rail contact should be directly contrasted with a detailed finite element model. This proceeding will allow to directly compare different methods on the bases of finite element analysis and thus the identification of a method for each situation.

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Micro-scale deterministic asperity contact FEM simulation

Kolli¹,

Winkler²,

Wartzack³

et al. 2022

Surf. Topogr.: Metrol. Prop.

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There are numerous stochastic approaches to indirectly couple solid asperity contact with the fluid hydrodynamics in the region of boundary or mixed lubrication. In contrast, deterministic approaches for calculating solid contact pressure curves offer advantages in terms of flexibility and accuracy. This contribution aims at providing a publicly available, automated method to derive solid asperity contact pressure curves for given surfaces, implemented in commercial software based upon Finite Element Method (FEM). Solid asperity pressure curves were calculated and compared to various established stochastic models for artificially generated surfaces and surfaces measured via laser scanning microscopy. Thereby, it was shown that the usage of artificially generated surfaces based on stochastic parameters only allowed an approximate representation of real measured surfaces as well as to lower calculated pressures, so that 3D measurement data is preferred to calculate the contact pressure. Moreover, the values of the FEM model were in a similar region but slightly below the stochastic models over a wide range of gap distances and the asperity pressure graphs were more curved/convex. At very small gap height values, the pressure in the FEM model reached values similar to the stochastic models. This was attributed to the fact that real surface topographies were considered, also allowing for peak-to-valley pairings instead of merely asperity-to-asperity contacts, as well as to the fact that the roughness and mean planes were re-calculated in each simulation step, while most stochastic approaches neglect the elastic deformation of asperities when determining the distances between the rough surfaces.

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Multiscale Finite Element Modeling of Wheel–Rail Rough Normal Contact Measurements Using Pressure Measurement Film

Cited by 5 publications

References 13 publications

Calibration of a finite element model of Prescale film for wheel-rail normal contact area measurements

Calibration of a finite element model of Prescale film for wheel-rail normal contact area measurements

Overview of methods to identify the static normal wheel-rail contact

Micro-scale deterministic asperity contact FEM simulation

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