Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations (2005) / Chapter Skim
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Appendix C - Investigation of Wheel Flange Climb Derailment Criteria for Transit Vehicles (Phase II Report)
Appendix C - Investigation of Wheel Flange Climb Derailment Criteria for Transit Vehicles (Phase II Report)
Pages 116-137
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From page 116... ...
C-1 APPENDIX C: Investigation of Wheel Flange Climb Derailment Criteria for Transit Vehicles (Phase II Report)
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From page 117... ...
The biparameter distance criterion based on the simulation results was validated by comparison with the research team's TLV test data. The application to two AAR Chapter XI performance acceptance tests and limitations of the biparameter distance criterion are also presented.
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From page 118... ...
• Application of the biparameter distance criterion to a test of a passenger car with an H-frame truck undergoing Chapter XI tests shows that the biparameter distance criterion is less conservative than the Chapter XI criteria, including the 50-msec criterion. • Application of the biparameter distance criterion to an empty tank car derailment test results show that the biparameter distance criterion can be used as a criterion for the safety evaluation of wheel flange climb derailment.
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From page 119... ...
Based on single wheelset simulation results, Phase II proposed a general flange-climb-distance criterion for transit vehicle wheelsets. The general flange-climb-distance criterion was validated by the flange-climb-distance equations in Appendix B, the Phase I report, for each of the wheel profiles with different flange parameters.
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From page 120... ...
based on the simulation data at an L/V ratio of 1.99 for each of these wheel profiles listed in Table C-1. Correlation analysis between the two coefficients m and n and the maximum flange angle and flange length were conducted to generate a general function expression.
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From page 121... ...
Based on the above analysis of the coefficients, a general flange-climb-distance formula with the following AOA and flange parameters is proposed: (C-5) where A and B are coefficients that are functions of maximum flange angle Ang (degrees)
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Table C-2 lists a range of limiting flange-climb-distance values computed using Equation C-5 for a specified range of flange angles, flange lengths, and AOAs. Table C-2 indicates C-8 that at lower AOA of 5 mrad, the limiting flange-climb distance increases as the wheel flange angle and flange length do.
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Figure C-9. Climb distance generated from Equation C-5 for different wheel profiles.
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An L/V ratio of 2.7 was considered conservative for freight cars. The general flange-climb-distance criterion in Chapter 2 of this appendix was derived from simulation results at a fixed L/V ratio of 1.99 for different AOAs, which was considered conservative for transit cars.
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From page 125... ...
3.2 THE BIPARAMETER CLIMB DISTANCE FORMULA AND CRITERION Due to the bilinear characteristics between the function of 1/D and the two variables shown in Figures C-13 and C-14, a gradual linearization methodology including two steps described below was developed to obtain an accurate fitting formula. First, the least squares fitting method for two variables was used to fit the simulation result.
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From page 126... ...
• The biparameter distance criterion is obtained by fitting in the bilinear data range where AOA is larger than Fitting Error Formula Value Simulation Value Simulation Value = − D [0.001411 *
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From page 127... ...
Figures C-16 through C-20 compare the simulation results with results of Equation C-11 for a range of AOA. Figures C-16 and C-17 show that Equation C-11 is conservative for AOA less than 5 mrad, with calculated climb distance shorter than the corresponding values from the simulations.
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Simulation Formula
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To demonstrate these differences, three TLV test cases at 32 mrad AOA were simulated by using the single-wheelset flange climb model. The friction coefficients in these simulations were derived from the instrumented wheelset L/V ratios.
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From page 130... ...
• For AOAs less than 5 mrad, the wheelset took most of the time to climb on the maximum flange angle. C-16 Corresponding to these two situations, the effects of flanging friction coefficients differ: • For AOA greater than 5 mrad, the climb distance decreases with a decreasing flanging friction coefficient µ because the lateral creep force changes direction on the flange tip to resist the derailment.
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From page 131... ...
superelevation, and with the AAR Chapter XI Dynamic Curve perturbation. Simulation results were used to estimate the AOAe during wheelset flange climb.
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Recommended conservative AOAe for practical use. Vehicle and Truck Type Straight Lines 5-Degree Curves 10 Degree Curves Above 10 Degree Curves Vehicle with Independent Rolling Wheel or Worn Three-Piece Bogies Others 10 5 10 15 20 Equation C-6 (Appendix B)
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From page 133... ...
7.1.2 Application of Biparameters Distance Criterion Equation C-11 was used to calculate a climb distance criterion for each run, based on the measured L/V ratios, flange angle, and flange length from the test wheels. Because AOA was not measured during the test, the Equation C-11 D AOAe < + 26 33 1 2 .
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From page 134... ...
Measured Formula, 7.6 mrad AOA Formula, 10 mrad AOA Formula, 13 mrad AOA Formula, 20 mrad AOA 50 msec Criteria at 20mph TABLE C-7 Passenger car test results: distance measured from the L/V ratio higher than 1.13 for friction coefficient of 0.5 Runs Speed L/V Maximum Average L/V Ratio Climb Distance rn023 20.39 mph 19.83 mph 19.27 mph 21.45 mph 1.79 1.39 5.8 ft rn025 2.00 1.45 6.3 ft rn045 1.32 1.23 0.7 ft rn047 1.85 1.52 5 ft
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From page 135... ...
The empty tank car derailment test results show that the biparameter distance criterion can be used as a criterion for the safety evaluation of wheel flange climb derailment. Figure C-31.
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From page 136... ...
• Application of the biparameter distance criterion to an empty tank car derailment test results showed that the criterion can be used in the safety evaluation on the wheel flange climb derailment. Application limitations of the biparameter distance criterion include the following: • The L/V ratio in the biparameter distance criterion must be higher than the L/V limit ratio corresponding to the AOA, because no flange climb can occur if the L/V ratio is lower than the limit ratio.
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From page 137... ...
2. Wu, H., and Elkins, J., "Investigation of Wheel Flange Climb Derailment Criteria," Report R-931, Association of American Railroads, Washington, D.C., July 1999.
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