Wheel forces during flange climb. II. NUCARS simulations

Elkins, J A; Shust, William

doi:10.1109/rrcon.1997.581395

Cited by 3 publications

(6 citation statements)

References 4 publications

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“…As shown in Figure 16, the critical derailment coefficients calculated according to the simplified formula (29) mentioned in this paper and the quasistatic formula (8) under critical derailment conditions are close to each other, especially when the wheelset yaw angle is high, and the two results approach each other. As shown in Figure 17, with increase of the friction coefficient, the error rate between the critical derailment coefficients calculated according to the simplified formula (29) and the quasistatic formula (8) under critical derailment conditions will increase to a certain extent; however, both of the errors are controllable within −5%∼5%, meeting the requirement of engineering application.…”

Section: Verification Of Accuracysupporting

confidence: 54%

“…Therefore, he pointed out that the sum of the derailment coefficients at both sides of the wheelset could be adopted as a criterion in evaluating wheel derailment, and, to a certain extent, corrected the conservative Nadal derailment evaluation criterion under small attack angles. Elkins and Shust [7,8] investigated the influence of friction coefficient and wheel-rail attack angle on rail climbing of wheels. They argued that rail climbing of wheels depended on the vehicle running distance when derailment coefficient is out of safe region rather than the duration of the unsafe derailment coefficient.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical 3D Model for Quasistatic Critical Derailment Coefficient of Railway Vehicles and a Simplified Formula

Wang

et al. 2018

Mathematical Problems in Engineering

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The formula for the critical derailment coefficient concerning wheelset yaw angles and wheel-rail creep forces is deduced based on the three-dimensional (3D) force equilibrium relationship in the critical wheel derailment state under quasistatic assumption. The change of critical derailment coefficient and wheel-rail contact patch normal force/creep force as wheelset yaw angles change under the influence of the friction coefficient, maximum flange angle, and net wheel weight is analyzed according to the Kalker linear creep theory and Shen-Hedrick-Elkins creep theory. Analysis shows that the wheel-rail friction coefficient and maximum wheel flange contact angle can significantly influence the critical wheel derailment coefficient, further proving the conservative results when the critical Nadal derailment coefficient is adopted in analyzing wheel derailment under small wheelset yaw angles. To realize easy calculation and application of critical 3D derailment coefficients, the ratio of lateral creep force to longitudinal creep force of wheel-rail contact patches under critical quasistatic wheel derailment conditions is deduced. A simplified calculation method of critical derailment coefficients is presented based on this. The calculation accuracy is verified, proving that it can satisfy engineering application.

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Section: Verification Of Accuracysupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Theoretical 3D Model for Quasistatic Critical Derailment Coefficient of Railway Vehicles and a Simplified Formula

Wang

et al. 2018

Mathematical Problems in Engineering

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“…There have been several successful experiments on flange climbing derailment, and reliable results on the effects of angle of attack on derailment coefficient at incipient derailment have been presented in the literature. 2,4,5,8 Thus, to check the effectiveness of the proposed criterion, the scaled tests conducted at Japanese National Railways (JNR) and the fullscale field tests conducted by the Transportation Technology Center, Inc. (TTCI) of the Association of American Railroads (AAR) are chosen to make the comparisons.…”

Section: Comparisons Of Proposed Criterion With Test Resultsmentioning

confidence: 99%

“…2,3 The validity of Nadal's criterion at small or negative values of the angle of attack has been extensively verified in the literature. [2][3][4][5][6][7][8][9][10][11][12] There have been numerous attempts to introduce new factors and improve Nadal's formula. For instance, Yokose 2 proposed a formula based on Levi and Chartet's results on the relationship between slip ratio and tangential force during flange climbing, and the formula was validated using 1/10 and 1/5 scaled experiments.…”

Section: Introductionmentioning

confidence: 99%

An angle of attack-based derailment criterion for wheel flange climbing

Guan

Zeng

Jin

2013

Proceedings of the Institution of Mechanical Engineers, Part F:

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A three-dimensional equilibrium model of a wheelset is created that takes the geometrical contact and non-linear creep force between the wheel and rail into account. This model can thus be used to study derailment conditions during flange climbing. To ensure the validity of Nadal’s criterion at small and negative angles of attack, the effects of the angle of attack and friction coefficient on an “equivalent friction coefficient”, which is defined as the ratio of the lateral creep force to the normal force, are studied. Using the results of the wheelset equilibrium equation, two curve-fitted formulas for the equivalent friction coefficient are generated in terms of the angle of attack and friction coefficient using, respectively, the Shen–Hedrick–Elkins creep theory and FASTSIM approach. A derailment criterion is proposed based on the curve-fitted equivalent friction coefficients, which takes the angle of attack, friction coefficient and contact angle into consideration. The effectiveness of the proposed criterion is verified through numerical comparisons with wheelset equilibrium equations for different contact angles and friction coefficients, and through experimental comparisons with scaled tests made by Japanese National Railways and full-scale field testing at the Transportation Technology Center, Inc.

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“…This relationship leads to the Nadal limit for the prediction of the onset of wheel climb. The difficulty of completely understanding wheel climb is illustrated by the large number of papers that have been written on this subject through the years including Gilchrist and Brickle [2], Weinstock [3], Elkins and Shust [4], [5] and Blader [6], [7]. It should be noted that the Nadal limit is accurate for high angle of attack (AOA) conditions associated with F tan > F long , as the wheelset rolls forward in quasi-static steady motion leading to a flange climbing scenario.…”

Section: Introductionmentioning

confidence: 99%

Application of Nadal Limit for the Prediction of Wheel Climb Derailment

Marquis

Greif

2011

2011 Joint Rail Conference

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Application of the Nadal Limit to the prediction of wheel climb derailment is presented along with the effect of pertinent geometric and material parameters.Conditions which contribute to this climb include wheelset angle of attack, contact angle, friction and saturation surface properties, and lateral and vertical wheel loads. The Nadal limit is accurate for high angle of attack conditions, as the wheelset rolls forward in quasi-static steady motion leading to a flange climbing scenario. A detailed study is made of the effect of flange contact forces F tan and N, the tangential friction force due to creep and the normal force, respectively. Both of these forces vary as a function of lateral load L. It is shown that until a critical value of L/V is reached, climb does not occur with increasing L since Ftan is saturated and the flange contact point slides down the rail. However, for a certain critical value of L/V (i.e. the Nadal limit) F tan is about to drop below its saturated value and flange climb (rolling without sliding) up the rail occurs. Additionally, an alternative explanation of climb is given based on a comparison of force resultants in track and contact coordinates.

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Wheel forces during flange climb. II. NUCARS simulations

Cited by 3 publications

References 4 publications

Theoretical 3D Model for Quasistatic Critical Derailment Coefficient of Railway Vehicles and a Simplified Formula

Theoretical 3D Model for Quasistatic Critical Derailment Coefficient of Railway Vehicles and a Simplified Formula

An angle of attack-based derailment criterion for wheel flange climbing

Application of Nadal Limit for the Prediction of Wheel Climb Derailment

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