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---==~ --Tr~opgrlaliow\ - llllO l"wbbo, Colocsdo 11001 Test
Cenrer
Mr. RobertS. Spratling Cont.ra.cting Officer
Federal Ra.1lroa.d Administration
1\ 55()( \ATIUN OF AJ,!EIUCAl'\
RAilROADS
Office of Acquisition s.nd Grants Services, RAD-30 400 Seventh street, S.W. Washington, DC 20590
Februa:ry 10, 1995 CON/ERW /95-()27
Tflc!u:(71Q) 58J-D672
Suqj: Dra.ft Fina.l Report - •weARS Modeling in SUpport of Freight ca.r Tolerance Side Bearing Clea.ra.nce Test •
Refr: Contract DTFR53-93-c-DOOO l, Task Order No. l 0 l, Modification No. 2
Dea.r Mr. Spratling:
Here. is the ~ect report for FRA review a.nd comment. It is AAR's intent to furnish the f'inaJ version within ten (10) da;ys from receipt of FRA's comments. Please fax
any ·changes to me on 719.584.0711 and we'll ma.ke a best efforts attempt to meet
our contractual obligation submission date of February 28, 1995 for the rmsJ version.
ERW;jp
oo: G. Deily, T~hultz,
y<!. Spons,
D. Cackovic P. Conlon
RDV-31 RDV-32(;L) RTC-Ql
K. Ha.wthorne C.Sha.nk
Sincerely,
ASSOCIATION OF AMERIC.A:ti R.AU..Jl.OADB
-;r~;Jt._· "7
Edward R. Walsh Contra.cts, Ma.n&ger
U.S. Department of Transportation
Federal Railroad Administration
Office of Research and Development Washington D.C. 20590
DOT/FRA/ORD-
NUCARS MODELING IN SUPPORT OF FREIGHT CAR TOLERANCE SIDE BEARING CLEARANCE TEST
Steven M. Belport
Association of American Railroads Transportation Technology Center Pueblo, Co 81001
February 1995 -DRAFT This document is available to the U.S. public through the National
Technical Information Service Springfield, Virginia 22161
DISCLAIMER
This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this report.
j_!.: . H·l·,,.
METRIC CONVERSION FACTORS Approximate Conversions to Metric Measures Approximate Conversions from Metric Measures
9 - 23 Symbol When You Multiply by To Find Symbol - Symbol When You Multiply by To Find Symbol
Know ___ 22 Know
LENGTH - - 21 LENGTH 8 - -
in inches *2.50 centimeters em - :::::::_---20
mm millimeters 0.04 inches in ft feet 30.00 centimeters em - em centimeters 0.40 inches in yd yards 0.90 meters m --- - 19 m meters 3.30 feet ft mi miles 1.60 kilometers km -= _ m meters 1.10 yards yd
7 - 1 B km kilometers 0.60 miles mi
A.BI;.A - - 17
--:= _ AREA in2 square inches 6.50 square centimeters cm2 --= 16 ft2 square teet 0.09 square meters m2
6 - cm2 square centim. 0.16 square inches in2
yd2 square yards 0.80 square meters m2 - - 15 m2 square meters 1.20 square yards yd2
mi2 square miles 2.60 square kilometers km2 - km2 square kilom. 0.40 square miles mi2
acres 0.40 hectares ha : ::- 14 ha hectares 2.50 acres (10,000 m2
) - 13
MASS {weight) 5 -= MASS lweiaht\ - 12
oz ounces 28.00 grams g ----:= g grams 0.035 ounces oz lb pounds 0.45 kilograms kg - - 11 kg kilograms 2.2 pounds lb
short tons 0.90 tonnes t : t tonnes (1 000 kg) 1.1 short tons (2000 lb) 4 - 10
: VOLUME - - 9
VOLUME ....::. ml milliliters 0.03 fluid ounces fl oz = - 8 I liters 2.10 pints pt
tsp teaspoons 5.00 milliliters ml 3 - I liters 1.06 quarts qt Tbsp tablespoons 15.00 milliliters ml -= - 1 I liters 0.26 gallons gal fl oz fluid ounces 30.00 milliliters ml : m3 cubic meters 36.00 cubic feet ft3 c cups 0.24 liters I _ - 6 m3 cubic meters 1.30 cubic yards y& pt pints 0.47 liters I qt quarts 0.95 liters I 2 - - 5 gal gallons 3.80 liters 1 TEMPERATURE (exact) ft3 cubic feet 0.03 cubic meters m3
- - 4 y& cubic yards 0.76 cubic meters m3
- 'C Celsius' 9/5 (then Fahrenheit 'F -
3 temperature add 32 temperature
TEMEERAIUBE (exact) 1 = - 2
'F Fahrenheit 5/9 (after Celsius 'C --= - 1 oF 32 9 6 ;:2 temperature subtracting temperature : -40 o 140 so a~. 120 160 200 I
32) inches -= em 1 I I I I 1 I 1. I 1 I I I I _ I I I 1 I I I II I . - I I I I I I I I I I -40 -20 20 40 60 80 100 oc 0 37 oc
• 1 in. = 2.54 em (exactly)
Table of Contents
1.0 INTRODUCTION ..................................................................................................... 1
2.0 OBJECTIVE ................................................................................................................ 1
3.0 PROCEDURE ............................................................................................................ 1
3.1 NUCARS DESCRIPTION .................................................................................. 1
3.2 MODEL DEVELOPMENT ................................................................................ 2
3.2.1 System File .................................................................................................. 2
3.3 MODELING MATRIX ....................................................................................... 2
3.4 NUCARS INPUT FILE PARAMETERS ........................................................... 3
3.4.1 Input File ..................................................................................................... 3
3.4.2 Wheel/Rail Geometry File ....................................................................... 4
3.4.3 Data File ...................................................................................................... 5
4.0 RESULTS .................................................................................................................... 6
4.1 MODELING ANALYSIS ................................................................................... 8
4.1.1 D5 Configuration ....................................................................................... 8
4.1.2 D5 Configuration With Suspension Damping ..................................... 12
4.1.3 D7 Configuration (Long Travel Suspension) ......................................... 16
4.2 VARIATION IN COEFFICIENT OF FRICTION ............................................ 20
4.3 VARIATION OF TRACK GAGE ...................................................................... 22
4.4 COMPARISON TO CHAPTER XI LIMITS ..................................................... 23
5.0 CONCLUSIONS ....................................................................................................... 25
5.1 GENERAL OBSERVATIONS- CAR BODY ROLL ....................................... 25
5.2 GENERAL OBSERVATIONS-- WHEEL LOADS ......................................... 26
6.0 RECOMMENDATIONS .......................................................................................... 26
DRAFT REPORT
1.0 INTRODUCTION
The Federal Railroad RA) sponsered a research project with the Associ-ation of American Ra' (AAR~anaged Transportation Technology Center (TTC), Pueblo, Colorado, to investigate th~ effects of varia_tions in side bearing clearance on the vechicle dynamics of a loaded freight car with a relatively high center of gravity. AAR's computer program NUCARS was used to simulate the car's dynamic behavior.
This investigation was a continuation of another project (T0101,1993), which also tested a loaded freight car with a high center of gravity (e.g.), but on the Vibration Test Unit in TIC's Rail Dynamics Laboratory and on track.1 These early comparisons, between on-track tests and limited computer simulations, found in the analysis performed by Volpe National Transportation Systems Center (VNTSC) provided a basis for the studies included in this report.2
2.0 OBJECTIVE
The objective of this investigation was to support previous (1993) on-track testing and analytical modeling to further determine the effect of side bearing clearance in the presence of various secondary suspension configurations on high e.g. cars. Further parameters investigated were track gage, wheel/rail coefficient of friction, secondary spring stiffness, and the effect of hydraulic damping. All vehicle configurations were simulated using various track input amplitudes.
Prior to modeling, a preliminary review of all test data was conducted to obtain a better understanding of the overall test results and to help in the direction of the modeling effort.
3.0 PROCEDURE
The modeling effort involved various model configurations including side bearing clearance, wheel/ rail coefficients of friction, car suspension, track input amplitude and track gage. The configurations modeled were based on comments from FRA and discussions with VNTSC personnel.3 Review of the test plan resulted in modifications of the test matrix. These changes were made to better suit the overall objectives of the test program. All configurations were modeled on mathematically generated 39-foot staggered joints using standard wheel/rail profiles on a high e.g. covered hopper car.
3.1 NUCARS DESCRIPTION
NUCARS is a generalized vehicle dynamics program used to aid in vehicle design and testing. Vehicles are simulated in NUCARS as an assembly of body masses linked by connections representing actual suspension components. The flexible
DRAFT REPORT 1
7
structure of the model allows the user to simulate the response of any vehicle to any
track input. Simulation output includes predicted body and wheel set displacements, suspension forces and strokes, wheel/rail interaction forces, and wheel and rail wear indices.
The required input to accurately describe a specific vehicle includes masses
and dimensions of major body components, moments of inertia, and detailed information on all suspension locations, stiffness, damping characteristics and the e.g. height.
The model simulated the NUCARS mode of predicting forces and car body response resulting from the dynamics of the rolling wheel on rail.
3.2 MODEL DEVELOPMENT
Development of the initial NUCARS model for this application was performed by
personnel from VNTSC. This information was used as a baseline for the TTC model
ing effort to eliminate duplication of effort.
The following changes were made to the NUCARS system file provided by VNTSC for the D5 spring configuration._ All changes were agreed to by VNTSC per
sonnel and TTC engineers.
3.2.1 System File
- .003 inch was added to the desired side bearing clearance due to the center plate
spring stiffness (ie .. 250 to .253), which then allowed proper settling of the car
body center bowl.
- The side frame wedge angle on the Barber truck was changed from 37.5 degrees
to 35 degrees, appropriate for this truck design.
- The vertical spring rate for the bolster spring nest was changed to a standard
100-ton spring rate for the D-5 simulations.
3.3 MODELING MATRIX
Table 1 summarizes the test matrix configurations used for the NUCARS modeling.
DRAFT REPORT 2
Table 1. Modeling Configurations
I Parameter II Configuration I Classification Covered Hopper
Loaded Car Body Weight 266,000 lbs
C.G Height 93.0 inches
Side Bearings Roller 688B
Truck Type Barber, Variable Damped S-2-C
Truck Spacing 40.5'
Side Bearing Clearance 1/4" and 3/8"
Truck Suspension D5, D5 w /Hydraulic Damping, and D7
Speed 10 to 20 and 20 to 10 mph
10 to 30 and 30 to 10 mph
Track Gage 56; 56.5, and 57 inches
Wheel Profile Standard AAR-1B
Rail Profile AREA136
Input Amplitudes 0.75, 1.0 and 1.25 inches
Wheel/Rail Coefficient of 0.1, 0.3 and 0.5
Friction
The basis for this model is the AAR102 covered hopper car. This car has a history of testing dating back to when it was part of the Norfolk Southern Car Rocker Test Facility for testing trucks and snubbing devices. AAR102 is used by AAR/TTC for the conduct of specification testing. The car is currently loaded with packed cement powder.
3.4 NUCARS INPUT FILE PARAMETERS
3.4.1 Input File
Track inputs based on a rectified sine waveform, shown in Figure 1, were used during all of the modeling cases. Three input amplitudes (0.75, 1.0 and 1.25)
DRAFT REPORT 3
were selected based on the test data review and consultation with VNTSC per
sonnel. The length of the input was sufficient to clearly identify resonant speeds,
generally 1250 to 2500 feet. The distance-based rate of the input was set at 0.0085
mph/ foot of distance traveled. This is equivalent to a 10 mph change in velocity over 1170 feet.
PRE:VU PREVU Uersion Z.OO Association of Anerican Railroads
Copyright (c) 1992
0.0,_------------~.~--~.-~~~~~--~~--~.-~~--~~--
-o.z
-0.4
, ' ' ' ' '
l ---------------------~----- ------ - ------' ' ' ' ' ' ' ' ' : _____________________ i _____ _
' '
-0.6 ---------------------~------- ,------ ------- ----' ' ' ' ' '
i ! -0.8+---~~--~--;---~~--~--1---~~--~---r' --~--~~--~
50 100 150 PLOTTING LEFT VERT & RIGHT VERT uersus DISTAHCE
200 FEET
Chp XI Twist & Roll Input; 10 staggered low joints (3/4 in) on 39 ft rail
Figure 1. NUCARS Input File -- 3/4"
3.4.2 Wheel/Rail Geometry File
A description of the contact between the wheels and rails is required to run a
railroad track simulation using NUCARS. This is contained in the wheel/ rail geometry (WRG) file. The WRG file used for all modeling cases consisted of a standard AAR 1B wheel profile on an AREA 136-pound rail. Track gage variation in the WRG file included standard, narrow, and wide gage configurations.
Figure 2 shows a NUCARS plot of rolling radius change with wheel set lateral
position for this combination of wheel and rail at standard gage. The 1:20
tapered tread region is apparent during tread contact. The transition up the
flange is fairly continuous until two point contact occurs.
DRAFT REPORT 4
PRE:VU PREVU Version 2.00 Association of A~erican Railroads
Copyright (c) 1992
25.0,_---------,.---------~---------.---------.---------.~--------, ' ' ' ' '
ze.e __________ -L--------------~--------------~--------------~--------------~- -----------, ' ' ! : : : I I I I
: : : : 15.0 --------------~--- ---------~--------------~--------------~--------- ----~--------------1 I I I I
I I I I I I I I I I
:
1 I I I I
I : : : :
10.0 --------------:---- ---------:--------------:--------------:--------- ----:--------------1 I I I I I I I I I I I I I I I I I I I
s.e --------------L------- -----L--------------L--------------L---- --------L--------------l : i : i ' ' ' 0.0 ______________ : ---------~- ---- -- : --------------
' ' ' ' ' -5.0+-~~~~~~~~~~~~~~~r' ~~~~-+~~~~~r-~~~~ -15.0 -10.0 -5.a 0.0 5.0 10.0 15.0
PLOTTING Wheel Rolling Radius L uersus Lateral DisplaceMent
WHEELSET AAR1BWF MEASURED 06/08/93 ON RAILS AREA1364 MEASURED 06/29/91
Figure 2. Wheel Rolling Radius versus Lateral Displacement
3.4.3 Data File
Table 2lists the primary measurements which were evaluated using the
NUCARS model. Additional measurements were also collected for diagnostic
purposes during preliminary analysis. All data channels collected during simu
lations were high-pass filtered at 15 Hz.
DRAFT REPORT 5
Table 2. VTU Test Measurements Predicted by NUCARS
I Description II Location
Car Body Roll Rotation Center
Vehicle Velocity n/a
Vertical Wheel Force Axle 1,2,3 & 4
Axle Roll Rotation Axle 1,2,3 & 4
Bolster Roll Rotation A &BEnd
4.0 RESULTS
Simulations were performed based upon the model and input criteria described in Section 3.0 of this report. The primary mode of data reduction was conducted by combining the peak-to-peak roll angles with speed for each major run configuration.
I
Figures 3 and 4 show typical NUCARS plots of car body roll; the peak-to-peak roll angle of 5.5 degrees occurred at 12 mph. Figure 5 shows a typical history plot of speed versus distance during a downward sweep from 20 to 10 mph.
DRAFT REPORT 6
PLOTVU X17.0UT NUCARS Version 2.055 27-Dec-94 Transportation Test Center, Pueblo, Colorado
degrees 3.0,_-----------.-----------.------------.-----------.-----------,
I I
' ' ' ' ' ' ' ' ' ' 2. 0 ----------- -- ~-----------------~------------------~-----------------
1.0
···wJ --------
-1.0 --------- - - -
1 • I I
' ' ' ' ' ' ' ' ' ' ' ' ~ ' ' ' ' ' ' '
' ' ' ' ' '
r-- --r ------ r
' ' ' ' - - - -- - ' -~-- --
' ' ' ' -2.0 ------------ - - ----------------~------------------~-----------------' ' ' ' ' ' ' ' ' ' ' ' ' '
-3.0+-----~------+-----~------~----~----~:,_----~-----+:------~----~ 10.0 12.€1 14.€1 16.€1 18.€1
Car Body Roll Gyro uersus Forward Velocity 3/8" sbc, 3/4" input amplitude (RECTIFIED sine), 2e TO 1e mph, mu =.5
Figure 3. Time History-- Car Body Roll Versus Speed
2e.e mph
PLOTVU X17.0UT NUCARS Version 2.055 27-Dec-94 Transportation Test Center, Pueblo, Colorado
degrees 3.0,_-----------.-----------.------------.-----------.-----------~
' ' ' ' ' ' ' ' ' ' 2.0 ------------------~-----------------~-----------------~- -
1.0
··~ -1.0 ----------- -
' ' ' ' ' ' ' ' ' ' ' ' '
- - - - -
' ' ' ' ' '
H· - - -
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' -2.0 ------------------!-----------------:----------------- - -- - - - - -! - -------------' ' ' '
-3.a+-~--~-.-,--+:--~-.-,--~-+:--,-~~--~~-,--~-r~,-4·--~-r--~~~ 25€1 see 75e 100€1
Car Body Roll Gyro uersus Distance along the Track 3/8" sbc, 3/4" input amplitude (RECTIFIED sine), 20 TO 1e mph, mu =.5
Figure 4. Time History -- Car Body Roll Versus Distance
DRAFT REPORT 7
1250 feet
X17.0UT NUCARS Version 2.055 27-Dec-94 PLOTVU Transportation Test Center, Pueblo. Colorado
20.0 lllph ~~~------:------------:1 -----------,-----------------------,
I I I I I I I I I I I 18.3 ------------------L- --------------~-----------------~------------------L-----------------1
I I I I I I I I I
: : : I I I I I I I I I I I I I I I I I I I I I
I I
---------------~------------------r-----------------------------------~-----------------i I I
16.0 I I I I I I I I I I I I I I I I
: I I I I I I I 14.0 ------------------~-----------------~----------------- -----------------~-----------------1 I
I I I I I I I I I I
: : I I I I
------------------L-----------------~-----------------~----------------12.0
1 I I I I I I I I I I I I I I I I I I I I I I I I I I
10.0+-~~~--~~:--~~~~--r: ~~~~~-+:~--~~~-+~--~~~~ o 250 500 750
Forward Velocity uersus Distance along the Track
3_...;8" she, 3/4" input a111plitude (RECTIFIED sine), 20 TO 10 111ph. 111u =.5
Figure 5. Time History-- Speed Sweep Versus Distance
4.1 MODELING ANALYSIS
1250 feet
Two performance measures were selected to analyze roll response from this modeling effort. The first is the maximum peak-to-peak roll angle. AAR freight certifica
tion standards place a limit of 6 degrees on this value. The second criterion is the
minimum vertical wheel load expressed as a percentage of the static wheel load.
AAR standards state that this value should not fall below 10 percent at any speed up
to the maximum operating speed.4 Values below this threshold identify potential
loss of wheel/rail contact and guidance. The following sections contain summary
plots from reduced data showing peak-to-peak car body roll versus speed of each
model configuration.
4.1.1 05 Configuration
Figures 6 through 8 show plots from the D5 truck spring configuration. Each
figure includes side bearing clearances of 1/4- and 3/8-inch side bearing
clearance. The figures are presented in order from 0.75, 1.00 and 1.25 track input
amplitudes respectively.
DRAFT REPORT 8
DRAFT REPORT
12
1/4' S.B. CLEARANCE X5.Xl4
14 16
SPEED(MPH)
--UPWARD SWEEP --e- DOWNWARD SWEEP
12
3/8" S.B. CLEARANCE X8,X17
14 16
SPEED(MPH)
--UPWARD SWEEP --e- DOWNWARD SWEEP
18
18
Figure 6. Car Body Roll Versus Speed 3/4" Input
9
20
20
14
8 12 ~
e. ~ 10 -l 0 z < -l -l 0 0:: ~ < ~ Q.,
0 f-~ < ~ Q.,
0
DRAFT REPORT
10 12
1/4' S.B. CLEARANCE X89,X90
14 16
SPEED (MPH)
--UPWARD SWEEP --DOWNWARD SWEEP
12
3/8" S.B. CLEARANCE X9l,X92
14 16
SPEED(MPH)
-- UPWARD SWEEP -- DOWNWARD SWEEP
18
18
Figure 7. Car Body Roll Versus Speed 1.0" Input
10
20
20
14
G' 12 r.LI 8 r.LI 10 -l 0 z < -l -l 0 ~
:.:: < r.LI ~
6 r-~ < r.LI ~
0
14
G' 12 r.LI 8 r.LI 10 -l 0 z < -l -l 0 ~
:.:: < r.LI ~
6 r-~ < r.LI ~
0
DRAFT REPORT
10
10
12
1/4' S.B. CLEARANCE X93,X94
14 16
SPEED (MPH)
--- UPWARD SWEEP --- DOWNWARD SWEEP
12
3/8" S.B. CLEARANCE X95,X96
14 16
SPEED (MPH)
--- UPWARD SWEEP --- DOWNWARD SWEEP
IS
18
Figure 8. Car Body Roll Versus Speed 1.25" Input
11
20
20
4.1.2 05 Configuration With Suspension Damping
Figures 9 through 11 contain plots from the D5 with hydraulic damping truck spring configuration. Each figure includes side bearing clearances of 1 I 4- and 3/8-inch side bearing clearance. The figures are presented in order from 0.75, 1.00 and 1.25 track input amplitudes respectively.
DRAFT REPORT 12
DRAFT REPORT
IS
1/4" S.B. CLEARANCE X77,X65
20
SPEED (MPH) 25
--UPWARD SWEEP --DOWNWARD SWEEP
3/8" S.B. CLEARANCE X78,X66
30
0 L_ ____________ L_ ____________ L_ ____________ L_ __________ ~
10 IS 20
SPEED (MPH) 2S
--UPWARD SWEEP --DOWNWARD SWEEP
Figure 9. Car Body Roll Versus Speed 3/4" Input
13
]0
DRAFT REPORT
1/4" S.B. CLEARANCE X79,X67
0 L_----------~-------------L------------~----------~ 10 15 20
SPEED(MPH) 25
-- UPWARD SWEEP --DOWNWARD SWEEP
3/8" S.B. CLEARANCE X80,X68
30
0 L_----------~-------------L------------~------------10 15 20 25 30
SPEED(MPH)
-- UPWARD SWEEP --DOWNWARD SWEEP
Figure 10. Car Body Roll Versus Speed 1.0" Input
14
DRAFT REPORT
15
1/4" S.B. CLEARANCE X81,X69
20
SPEED (MPH) 25
--- UPWARD SWEEP --- DOWNWARD SWEEP
15
3/8" S.B. CLEARANCE X82,X70
20
SPEED (MPH) 25
--- UPWARD SWEEP --- DOWNWARD SWEEP
Figure 11. Car Body Roll Versus Speed 1.25" Input
15
30
30
4.1.3 07 Configuration (Long Travel Suspension)
Figures 12 through 14 contain plots from the D7 truck spring configuration. Each figure includes side bearing clearances of 1 I 4- and 3 I 8-inch side bearing clearance. The figures are presented in order from 0.75, 1.00 and 1.25 track input amplitudes respectively.
DRAFT REPORT 16
1/4" 8.8. CLEARANCE X83,X71
14
6 12 ~ e ~ 10 ..J 0 z ..: ..J ..J 0 ~
::.:: ..: ~ ~
$ 4
::.:: ..: ~ ~
0 10 15 20 25 30
SPEED(MPH)
...._ UPWARD SWEEP -e- DOWNWARD SWEEP
3/8" 8.8. CLEARANCE X84,X72
14
6 12 ~
e ~ 10 ..J 0 z ..: ..J ..J 0 ~
::.:: ..: ~ ~
6 4 E-~ < ~
: t ~
• • 10 15 20 25 30
SPEED(MPH)
...._ UPWARD SWEEP -e- DOWNWARD SWEEP
Figure 12. Car Body Roll Versus Speed 3/4" Input
DRAFT REPORT 17
14
0 12
~
8 ~
10 ...J 0 z <: ...J ...J 0 0:: ::..: <: ~ Q.,
6 E-;' ::..: <: ~ Q.,
0
14
0 12
~
8 ~
10 ...J 0 z <: ...J ...J 0 0:: ::..: <: ~ Q.,
6 f-. ~ <: ~ Q.,
DRAFT REPORT
10
1/4" S.B. CLEARANCE X85,X73
15 20 25
SPEED(MPH)
--UPWARD SWEEP -- DOWNWARD SWEEP
15
3/8" S.B. CLEARANCE X86,X74
20
SPEED (MPH) 25
-- UPWARD SWEEP -- DOWNWARD SWEEP
Figure 13. Car Body Roll Versus Speed 1.0" Input
18
30
30
1/4" S.B. CLEARANCE X87,X75
I~ '
G " f [J..l Q
[J..l I ..J 10
0 z -< ..J ..J 0 0::: ::.:: -< [J..l r:>...
6 f-~ -< [J..l r:>...
0 10 15 20 25 30
SPEED (MPH)
--UPWARD SWEEP -- DOWNWARD SWEEP
3/8" S.B. CLEARANCE X88,X76
14
G 12 [J..l
B -~ 10
0 z -< ..J ..J 0 0::: ::.:: -< [J..l r:>...
6 4 !-;' ::.:: -< [J..l r:>...
0 10 15 20 25 30
SPEED (MPH)
-- UPWARD SWEEP -- DOWNWARD SWEEP
Figure 14. Car Body Roll Versus Speed 1.25" Input
DRAFT REPORT 19
4.2 VARIATION IN COEFFICIENT OF FRICTION
Figures 15 through 17 show history plots of car body roll versus speed for each variation of the wheel/rail coefficient of friction (0.1, 0.3, and 0.5.). Results from these plots show that no significant differences in car body roll were detected when the wheel/rail coefficient of friction was changed. This analysis, conducted at the beginning of the modeling runs, concluded.that a wheel/rail coefficient of friction of 0.5 would be used for the remainder of the modeling runs.
DRAFT REPORT 20
PLOTVU I X16.0UT liUCARS Version 2.055 27-Dec-9"1 Tr~tnsportat. ton Test Center~ Pueblo~ Co lorado
3.0 degrees
2.0
~iii"~M~~MM~r:-~it[~:~~:~ 1.0
0.0
-1.0
-2.0
: : : : -3.0 ! : i
Hl.O 12.0 11.0 16.0 16.0 20.0
l!i.mii~DJmDI.~II;a•'l~i11~JU:I; 1 SiiZ:.!mm::IU!I nph
1/-t" sbc, 3/"''" input. anplit.ude <RECTIFIED sine), 20 TO 10 r.ph. nu ::;:;.1
Figure 15. Time History -- Car Body Roll Versus Distance COF = .1
PLOTVU X15.0UT liUCARS Version 2.055 26-Dec-9"1 Transportation Test Center~ Pueblo, Colortt.do
degrees 3.0,_--------~--------~------~--------~---------,
2. 0 ------------------t·------ - - -r-----------------:-----------------1. e __________________ L:, ____ • •
!" -
-1.0 ----------------·-t··- -
~:::+-------------~-------------~~-----------~-----~----~-----~r_-_--_--_--~--------------+r------------~----------~--10.0 12.0 11.0 16.0 16.0 20.0
l!ttr!MitijfTWIGJIMhiiQ•Mii3f11f¥§•iQ161J,Wif9ti!S!I0 nph 1/4" sbc, 3/4." input anplitude (RECTIFIED sine), 29 TO 10 r.ph. n~u =.3
Figure 16. Time History -- Car Body Roll Versus Distance COF = .3
PLOTVU XH.OUT liUCARS Version 2.055 26-Dec-9"1 Transport.at fen Test Center, Pueblo, Co lorado
Figure 17.
DRAFT REPORT
degrees 3.0,_--------,---------~------~--------~---------,
2. 0 ------------------t··----- - - -:------------------:-----------------1.0 -----------------+---- ' - - - - - '
o.o
10.0 12.0 H.O 16.0 16.0
•ftt!W:nr;rrw:m••n••A·*'I4f1'f'-Mi"'4'6'J·••mmaum "Ph 1/"'1" sbc, 3/4" inJIUt anaplit.ude <RECTIFIED sine), 20 TO 10 RJlh, nu "'.5
Time History -- Car Body Roll Versus Distance COF = .5
21
4.3 VARIATION OF TRACK GAGE
Figures 18 and 19 show x-y plots of peak-to-peak car body roll versus speed during the two test modes (sweep-up and sweep-down). Configurations of narrow (56 inch), standard (56.5 inch), and wide (57 inch) track gage are included in each plot. Both test modes consistently defined that the greatest peak-to-peak car body roll occurred when a narrow track gage of 56-inches was used. Since the change in the peak-to-peak roll angle was typically less than 1 degree, the remainder of the modeling runs were conducted using an standard track gage (56.5 inches).
CARBODY ROLL ANGLE X5,X25,X5W (SWEEP UP)
IL-------~------~--------~------~------~ 10 12 14 16 18 20
SPEED(MPH)
-- 56.5 GA -+- 56 GA ......- 57
Figure 18. Variation of Track Gage-- Sweep Up
DRAFT REPORT 22
CARBODY ROLL ANGLE Xl4,X34,X44 (SWEEP DOWN)
I L--------L--------~------~--------~------~ 10 12 14 16 18 20
SPEED (MPH)
--- 56,5 GA --+- 56 GA -r- 57
Figure 19. Variation of Track Gage -- Sweep Down
4.4 COMPARISON TO CHAPTER XI LIMITS
Figures 20 through 22 show plots of compiled wheel loads and peak-to-peak car
body roll angles for each of the three input amplitudes, 0.75 inch, 1.0 inch and 1.25
inch. Each plot shows a comparison between the values obtained from selected sim
ulations and the allowable AAR specification limits for car body roll and minimum
vertical wheel load.
DRAFT REPORT 23
DRAFT REPORT
15
;;;-U.l U.l 0:: CJ U.l e 10
...l
...l 0 0:: ~ < U.l c.. 6 f-~ < U.l c..
DS SPRINGS
b.
b.
b.
--- -
l/4UP 3/l! UP l/4DN 3/RDN
• PEAK-TO-PEAK ROLL
_CHI! LIMIT
0.751NPUT DS W/DAMPING
b. b. b. b.
- - - -I/4DN 3/RDN
1/4 UP 3/l! UP
CONFIGURATION
D7 SPRINGS
b.
b.
b.
-- -
I/4UP 3/8 UP 1/-lDN
6 MIN. VERT. WHEEL LOAD
25
;;;-c..
20 :;;: U.l u
b. 0::
15 0 "-...l U.l
= 10 §: - ...l
< u 1= 0:: U.l >
3/8DN
Figure 20. Wheel Loads and Car Body Roll Plot-- 3/4" Input
DS SPRINGS 1.00 INPUT
DS W/DAMPING D7 SPRINGS 15 r--------------,-----------------,--------------0
I/4UP 3/8 UP l/4DN 3/8DN
• PEAK-TO-PEAK ROLL
_CHI! LIMIT
b.
b.
b. b.
b.
l/4DN 3/8DN 1/4 UP 3/8 UP 114 UP 3/8 UP l/4DN 3/SDN
CONFIGURATION
6 MIN. VERT. WHEEL LOAD
25
;;;-c..
20 :;;: U.l u 5
15 L.:..
~ :iS :c
10 :::: ...l < u 1= 0:: U.l >
Figure 21. Wheel Loads and Car Body Roll Plot --1.00" Input
24
1.25 INPUT 05 SPRINGS 05 W/DAMPING 07 SPRINGS
15 25
"' ~ (J..l (J..l - 20 ~ c:::: 0 :..t..l (J..l - u e 10 c::::
0 ...l 15 ~ ...l
"' ...l 0 WJ c:::: "' w..::
)<! :t -< 10 ~ (J..l Q.. ...l 6 "' -< u c- ;:: 1= ~ c:::: -< (J..l (J..l > Q..
I/4UP 3/8UP I/4DN 3/8DN I/4UP 318UP I/4DN 3/SDN 1/4UP 318UP l/4DN 3/SDN
CONFIGURATION
- PEAK-TO-PEAK ROLL "'
MIN. VERT. WHEEL LOAD
_CHI! LIMIT
Figure 22. Wheel Loads and Car Body Roll Plot -- 1.25" Input
5.0 CONCLUSIONS
The following observations are based on the modeling configurations included only in this report. These observations may not, in some cases, directly apply to the previous test data where a much wider spectrum of testing was analyzed. Typical examples include prior test data from configurations of 1/8 inch, 1/2 inch and 3/4 inch side bearing clearance, compared to observations of 1/4 inch and 3/8 inch included in this report.
5.1 GENERAL OBSERVATIONS- CAR BODY ROLL
Downward sweep runs always produce a lower frequency peak roll angle when compared to the upward sweep. Typically, it is of greater amplitude than the upward sweep.
Vehicle roll angle increases with input amplitude; the largest, increased between 0.75- and 1.0-inch input amplitude.
The variation of side bearing clearance modeled, 1/4 inch and 3/8 inch, had little influence on roll angle. Previous test results showed that larger side bearing clearance gap changes did affect car body roll angles.1
Spring type (D5 vs D7) has a very small effect on peak-to-peak roll angle.
DRAFT REPORT 25
Hydraulic damping significantly reduces the peak-to-peak roll angle. Wheel/ rail coefficient of friction and track gage have a negligible impact on roll angle.
0.75-inch input produced no roll angle in excess of the AAR 6-degree limit. For the 1.00-inch input amplitude, D5 and D7 undamped configurations, 6 of 8 simulations produced peak-to-peak roll angles above the 6-degree specification limit.
At 1.25-inch input amplitude, all configurations without additional damping exceeded the 6-degree limit. All cases produced peak-to-peak roll angles between 10 and 12 degrees.
5.2 GENERAL OBSERVATIONS-- WHEEL LOADS
For 0.75-inch input amplitude, the minimum wheel load is never less than 30 percent of static wheel load regardless of spring/ damper arrangement. For the D5 damped arrangement it is never less than 60 percent of the static load. It is anticipated that very worn trucks with lower damping capability as tested previously, could have produced wheel unloading of greater significance if modeled.
With 1.0-inch input amplitude, half of the cases produced wheel lift although none of these were with hydraulic damping. At 1.25-inch input amplitude, all D5 and D7 configurations without hydraulic damping generated wheel lift.
With 1.25-inch input amplitude, D5 configuration with hydraulic damping maintained at a minimum of 18 percent of static wheel load.
6.0 RECOMMENDATIONS
This study covered only a small range of possibilities in terms of harmonic roll response for high e.g. vehicles. The repeated jump response detected with the upward and downward sweeps illustrate the difficulty in identifying a safe, low operating speed.
The different side bearing clearances modeled, 1/4 inch and 3/8 inch, provide little or no additional margin of safety. Hydraulic damping at its optimal level can greatly reduce the risk of wheel lift and therefore derailments. The durability of hydraulic dampers may still be questionable in addition to these benefits given purchase, installation, and maintenance expense.
If the roll performance is a proven safety concern, then additional investigation of roll moderation techniques should be performed. This should also include a survey of the track geometry for amplitude, wavelength, and repeat distance.
DRAFT REPORT 26
A vehicle survey with regard to the population of vehicles equipped with vertical damping would also be of value. An estimate of high e.g. limits typically produced should be tabulated. Upon completion, a program consisting of testing and computer modeling should be developed to verify new railcar designs and track safety standards.
DRAFT REPORT 27
References 1. Cackovic, Dave L., Kerry Hopkins, David Tyrell. "Side Bearing Clearance Testing
Research." Federal Railroad Administration, FRA/ORD/94-11, May 1994. 2. Dorsey, C., David Tyrell, Herb Weinstock, R. Greif. "Analysis of Tests Conducted to
Determine the Influence of Side Bearing Clearance of Freight Car Harmonic Roll Behavior." U.S. Department of Transportation Volpe National Transportation Systems Center, Cambridge, MA, 1994 ASMEPaper.
3. Weinstock, Herbert, E-Mail Message to Tom Schultz (FRA)--AAR-Modification to T0101. U.S. Department of Transportation Volpe National Transportation Systems Center, Cambridge, MA, October 13, 1994.
4. Association of American Railroads, Manual of Standards and Recommended Practices. "Chapter XI Service-Worthiness Tests and Analysis for New Freight Cars." Washington, DC., 1991.
DRAFT REPORT 28