Download - Norma Pitch Bounce
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Shock and Vibration in Rail and other Transport Modes
William C. Shust
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2007OBJECTIVE ENGINEERS, INC.
Acknowledgements
z AAR / TTCIz ASF-Keystone, Union Pacificz FRAz Chicago Transit Authorityz Norfolk Southernz Monsanto Companyz International Truck & Engine
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2007OBJECTIVE ENGINEERS, INC.
No, No, No
That regular rock.
Me need Phillips.
Bills
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2007OBJECTIVE ENGINEERS, INC.
Broad overview of shock & vibration issues in railroading
z Vibration issues z Typical mechanical shocksz Various industry test standardsz Mitigation techniquesz Brief comparison of other transport modes to
the rail shipping environment.
z Technical conclusionsz Future trends for S&V in railroading
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2007OBJECTIVE ENGINEERS, INC.
SHOCK & VIBRATION ISSUES
Overall car stability Component strength Human comfort Cargo damage
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2007OBJECTIVE ENGINEERS, INC.
A closer look at the railcar environment: dynamic excitations
VehicleVehicle
Bogie and Unsprung Mass
Bogie and Unsprung Mass
Irregular running surfaces of wheel and rail[Wheelflats, out-of-round wheels, wheel corrugation,
rail corrugation, dipped welds and joints, shelling, etc]
Irregular running surfaces of wheel and rail[Wheelflats, out-of-round wheels, wheel corrugation,
rail corrugation, dipped welds and joints, shelling, etc]
Track components[Rail bending, railpads, tie bending,
ballast and subgrade]
Track components[Rail bending, railpads, tie bending,
ballast and subgrade]
Wheel/rail noise[Rolling and impact noises from irregularities on
wheel and rail, and squeal from stick-slip vibration]
Wheel/rail noise[Rolling and impact noises from irregularities on
wheel and rail, and squeal from stick-slip vibration]
0 - 20 Hz0 - 20 Hz
0- 500 Hz0- 500 Hz
0 - 1500 Hz0 - 1500 Hz
0 - 1500 Hz0 - 1500 Hz
0 - 5000 Hz0 - 5000 Hz
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2007OBJECTIVE ENGINEERS, INC.
At the low frequency end: rigid carbody motions
z Pitch & bounce, yaw & sway, twist & roll, lateral hunting all under 4 Hz
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2007OBJECTIVE ENGINEERS, INC.
60 Wavelength
Right RailVerticalPosition
Left RailVerticalPosition
0.75 Amplitude
Roll Input for AAR Chapter XI spec.(Left and right track vertical profiles)
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2007OBJECTIVE ENGINEERS, INC.
0
1
2
3
4
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0 20 40 60 80Simulated operating speed (mph) over repeated 3/4-inch twist and
roll perturbations
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60ft D.C.32ft Flatcar
0.6 Hz resonance -- Carbody roll(constant amplitude cross-level deviations)
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2007OBJECTIVE ENGINEERS, INC.
Typical Twist & Roll resonance (generic tank car, 18 mph, 39 cusps)
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2007OBJECTIVE ENGINEERS, INC.
More low freq. behavior ~ 2 Hz Wheelset Lateral Hunting
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2007OBJECTIVE ENGINEERS, INC.
At the high frequency end -- potential fatigue of & on circuit boards
Small mechanical fittings on a high frequency source (100-200 Hz)
PC Board bending (70-150 Hz)
Tiny cantilevered components (up to 1500 Hz if small enough)
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2007OBJECTIVE ENGINEERS, INC.
A few peculiarities related to certain car types
z Covered hoppers high CG, car rock-offz Tank Cars tors. stiff, track twist sensitivez Conversion of 89 flats to early car haulersz Heavy duty span bolster cars (8+ axles)z Lighter weight coal cars
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2007OBJECTIVE ENGINEERS, INC.
Example project A: Infrequent top chord yielding of coal cars
Suspension bottoming, or component strength?
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2007OBJECTIVE ENGINEERS, INC.
-5000
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0 10 20 30 40 50 60Train Speed (mph)
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6000 miles later; several dozen data bursts in 5 general groups
-3500ueDesignLimit
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2007OBJECTIVE ENGINEERS, INC.
Vertical Bounce Detail ~ 1.9 Hz: Strain, neg(Accel.), Spring Deflection
Time (Secs)4 4.5 5 5.5 6 6.5 7
0.6
0.4
0.2
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Vibration issue: Over time, a little bounce leads to more bounce
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2007OBJECTIVE ENGINEERS, INC.
Quasi-static event: Rotary Car Dumper Coal Unloading ~ highest strains of test
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2007OBJECTIVE ENGINEERS, INC.
Example project B: Development of a test spec. for aftermarket hardware
ABCD
TOR nozzle location at end of sand bracketTruck frameElectrical control cabinetCompressor room floor
(Note: Locationsvary slightly withlocomotive type)
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2007OBJECTIVE ENGINEERS, INC.
1
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1000
1 2 3 4 5 6 7 8 9 10Correlation with Field Environment
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Lab tests are always a compromise between reality and cost
Over-the-Road Simulation, Whole Vehicle
Sine Sweep or Dwell, Single Axis
Multiple Axes, Shaped Random
Single Axis, Shaped Random Single Axis, Shaped Random
0 500 1000 1500 2000
10-4
10-3
10-2
10-1
100
810F Min. Integrity = 7.6 grms
MIL-STD-810F and IEC61373 Vibration Spectra
Frequency (Hz)
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810F Rail 0.49 grms
IEC bogie long. 2.0 grms
IEC bogie lat. 3.8 grms
IEC bogie vert. 4.3 grms
Single Shaker, Random Flat PSD
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2007OBJECTIVE ENGINEERS, INC.
Mid-cost & moderately real: Random Shaker Input With Same Frequency Content As Field
time (secs)232 233 234 235 236 237
10
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-10
-15
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CD12_072 Y
time (secs)70 71 72 73 74 75
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-15
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CD3_072 Y
time (secs)215 216 217 218 219 220
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CD6_121 Y
97th Percentile Data Records
Random shaker drive file with similar energy distribution; similar
but more frequent peaks
66
72.080.1250
=
=
fieldRMS
labRMS
gg
5 second segment0
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Random Vibration with similar Energy Distribution as SideFrame
(e.g. Time Compression 250X)
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2007OBJECTIVE ENGINEERS, INC.
Data collection on locomotive type A: Sander Bracket
Tri-axial access. on sander bracket:
at side frame (upper)
at free end (lower)
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2007OBJECTIVE ENGINEERS, INC.
Data collection on locomotive type B: Sander Bracket
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2007OBJECTIVE ENGINEERS, INC.
Revenue Service Routesfor Locomotive Vibration Tests
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2007OBJECTIVE ENGINEERS, INC.
Overall Comparison PeakAccelerations versus Location
1
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100
1000
Contr
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Fron
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Lube
Res
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Journ
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Field Data to Lab Test Conversion Process
z Reduce field data Using all valid files, compute aggregate (damage-
equivalent) side frame RMS accelerations Envelope resulting shape of severe PSDs (power
spectral densities)z Simplify PSD envelope, amplify to compress shake
table time Select 10-20 breakpoints for PSD shape Scale for 250:1 time compression vs. field
z Augment 8-hour shaker period (per axis) with brief segments achieving similar g level extremes as found in field data
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2007OBJECTIVE ENGINEERS, INC.
Locomotive Bearing Box Raw Vibration
time (secs)327.4 327.5 327.6 327.7 327.8
120
80
40
0
-40
-80
-120
time (secs)327.4 327.5 327.6 327.7 327.8
120
80
40
0
-40
-80
-120
251. g peak-to-peak, vertical direction
Almost all energy around 500 Hz
Estimated 0.01double amplitude displacement
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2007OBJECTIVE ENGINEERS, INC.
Locomotive Bearing Box Same data in freq. domain (PSD)
Block length = second
Bandwidth = 2 Hz
N=144 blocksFrequency (Hz)
0 100 200 300 400 500 600 700 800 900 1000
101
100
10-1
10 -2
10 -3
10 -4
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Frequency (Hz)0 100 200 300 400 500 600 700 800 900 1000
101
100
10-1
10 -2
10 -3
10 -4
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2007OBJECTIVE ENGINEERS, INC.
Most Severe Spectra from 2 loco. types and two service routes
Frequency (Hz)25 50 75 100 125 150 175 200 225 250
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
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Lateral Spectra (Auto Parts Service)10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
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10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
Frequency (Hz)25 50 75 100 125 150 175 200 225 250
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
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Lateral Spectra (Coal Service)10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
10 0
10 -1
10 -2
10 -3
10 -4
10 -5
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2007OBJECTIVE ENGINEERS, INC.
PSD Envelope of Many Field Spectraand simplified shake table Breakpoints
200 400 600 800 1000
10-4
10-3
10-2
10-1
100g
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Freq. (Hz)
Overall lateral ampl. using breakpoints: 1.8 g RMS
200 400 600 800 1000
10-4
10-3
10-2
10-1
100g
*
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/
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Freq. (Hz)
Overall lateral ampl. using breakpoints: 4.47 g RMS
200 400 600 800 1000
10-4
10-3
10-2
10-1
100g
*
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Freq. (Hz)
Overall lateral ampl. using breakpoints: 1.8 g RMS
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2007OBJECTIVE ENGINEERS, INC.
Summary of Shake Table Amplitudes (compared to MIL & Euro. specs)
Location 120-day Simulations Brief Field ExtremesCab Vertical 0.26 1.32 0.81Compressor Vertical 0.52 1.31 0.81Plow Longitudinal 0.26 1.44 0.40Sideframe Lateral 1.80 4.32 3.77Unsprung Vertical 10.5 44.5 30.6MIL-STD-810F Rail Transport
0.49
MIL-STD-810F "Minimum Integrity" 7.7
Proposed Shake Table Vibration (g RMS) IEC 61373
"Long Life"
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2007OBJECTIVE ENGINEERS, INC.
Finally Add Representative Thermal Cycling (-40 to 130 F)
012345
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0306090
120150
Time
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LateralDay 1
Long.Day 2
Vert.Day 3
Lat.Day4
Record Vibr. andSample Spray 2-Minute Field Extremes
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2007OBJECTIVE ENGINEERS, INC.
Proof of test: freezing, shaking & baking a locomotive rail friction-modifier nozzle.
Electro-magnetic shaker with 15000 pounds of force
Heating/cooling source
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2007OBJECTIVE ENGINEERS, INC.
Collection Grid Pans to check Spray Pattern and Application Amount
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2007OBJECTIVE ENGINEERS, INC.
Final product: AAR spec. of minimum performance, before fleet installations
Clean nozzle After build-up
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2007OBJECTIVE ENGINEERS, INC.
0 5 10 15 20 25 3010
-3
10-2
10-1
100
Human Comfort Issues ISO-2631 (empirical weighting of spectra)
Original Signal 0.83 g rms
Energy Spectrum
Weighting Values
Final Area 0.63 g weighted
0 30 Hz
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Time (sec)PSD
Similar process for noise dBA
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2007OBJECTIVE ENGINEERS, INC.
TYPICAL SHOCKS
Car coupling In-train forces (slack action) Wheel imperfections Suspension bottoming out Rattling pieces
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2007OBJECTIVE ENGINEERS, INC.
Coal Car Project A -- revisitedZero Speed Yard Data, Unattended (unexplained)
0.2
0
-0.2-1
-1.2
-400-1000-1600-2200
Time (Secs)993600 10 6 1.02*10 6
10
5
0
Vertical Car Body Accel.
Vert. Spring Defl.
Top Chord Strain
Train Speed
1 4 1 5 1 6
-1 6 0 0
-2 0 0 0
-2 4 0 0
-2 8 0 0
-3 2 0 0
-3 6 0 0
-4328 ue for 1/15th sec, then 2 hours at 2000 ue before relaxing
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2007OBJECTIVE ENGINEERS, INC.
0 1 2 3 4 5 6 7
x 104
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Accel
Shock events produce accelerations with energy into higher frequencies
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2007OBJECTIVE ENGINEERS, INC.
0 1 2 3 4 5 6 7
x 104
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Strain Gage
But unlike car bounce, the shock accelerations are not scaled duplicates of strains
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2007OBJECTIVE ENGINEERS, INC.
And thus, a common 4g Design spec. willbe exceeded by high-freq. accel. data
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2007OBJECTIVE ENGINEERS, INC.
One coupling shock: accel. filtered at 4 freqs., and coupler load cell trace
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2007OBJECTIVE ENGINEERS, INC.
Similar sampling/filtering questions for various impacts related to passing wheels.
_ _ _
Collection Time(secs)20 40 60 80 100 120
-300-200-1000
100200300
Filter_010.sif - [email protected]_1.f.f
Collection Time(secs)20 40 60 80 100 120
-300-200-1000
100200300
Original Data Lowpassed at 333Hz=fc
After instead applying 10 Hz Lowpass filter
Revenue Train Sampled at 1000 Hz
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2007OBJECTIVE ENGINEERS, INC.
Zoom in on only 6 seconds
Original Data 333Hz=fc
Filter_010.sif - [email protected]_1.f.f
Collection Time(secs)60 61 62 63 64 65 66
-300-200-1000
100200300
After applying 10 Hz Lowpass filter
_ _ _
Collection Time(secs)60 61 62 63 64 65 66
-300-200-1000
100200300
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2007OBJECTIVE ENGINEERS, INC.
Rail Strain Gage with various lowpass filtering
0%10%20%30%40%50%60%70%80%90%
100%
0 50 100 150 200 250 300 350
Filter cutoff Frequency (Hz)
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Max is 95%
Min is 41%, Whats going on?
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2007OBJECTIVE ENGINEERS, INC.
Answer found by again zooming in on the original data
Collection Time(secs)60.00 60.25 60.50 60.75 61.00
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-300
-200
-100
0
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200
300
Different frequency content !
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2007OBJECTIVE ENGINEERS, INC.
A SAMPLING OF INDUSTRY STANDARDS (S&V and related issues)
Car body stability & healthTrack health
Car component health
Cargo stability & healthLongitudinal shock
Human stability & comfort
Locomotive specific issues
z FRA 213 Track Geometryz AAR Chapter XI, and M-
976 specsz Wheel Impact Detectorsz AAR S-4200 ECP brake
specz pending AAR brake beam
workz IEC-61373z AAR Dam. Prev. Stds.z MIL-STD-810z ISO-2631 ride comfortz AAR on-board rail
lubricator vibration spec
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2007OBJECTIVE ENGINEERS, INC.
Another recent example, AAR S-4200 ECP brake spec
Design to withstand:z Vibrations 0.4 g rms 1-150 Hz (with +/-3 g
peaks)z Half-sine shocks of 10g peak (20 50 msec)z If on car strength members, local
resonances can raise levels to: 15g (100-150 Hz) 50g (200-500 Hz)
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2007OBJECTIVE ENGINEERS, INC.
S & V MITIGATION TECHNIQUES
z Limit input energy availableTrack geometry standardsWheel flat limits, wheel impact detectors
z Interrupt transmission paths Spring/elastomer isolators
between car components between loco. structure & crew track to ground
z Add damping, stiffness, mass
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2007OBJECTIVE ENGINEERS, INC.
Limit the dynamic excitations to carsvia geometry or speed limits
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2007OBJECTIVE ENGINEERS, INC.
Title 49 CFR, Part 213Track Safety Stds. (track geometry specs.)
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2007OBJECTIVE ENGINEERS, INC.
WILD Detectors: maintain wheels based on revenue track impacts
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2007OBJECTIVE ENGINEERS, INC.
Transmission and reflections of rail vibration are highly site dependent
from Transit Noise and Vibration Impact Assessment, Hanson, Towers, and
Meister, Fed.Transit.Admin. 2006
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2007OBJECTIVE ENGINEERS, INC.
Earth vibration due to freight trains
50556065707580859095
0 10 20 30 40 50Distance from Track (m)
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2007OBJECTIVE ENGINEERS, INC.
Noise, Squeal and Corrugation(A human perception problem)
z Potential Solutions Grinding to remove
corrugation Improve curving via
W/R profile Lubrication Reduce surface
roughness of wheel turning and rail grinding
Structural or surface changes to wheel (block or cut sound transmission path)
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2007OBJECTIVE ENGINEERS, INC.
Chicago Transit Authority: Wheel screech damper
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2007OBJECTIVE ENGINEERS, INC.
More costly transit N&V mitigation
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2007OBJECTIVE ENGINEERS, INC.
Example project C: (rarely) we come across a beneficial use of vibration
z Civil engineers brought us dynamic track stabilization for after tamping operations
z Essentially a combination of adding stiffness/strength via aggregate material
change delaying the time when small bounces will
beget bigger bounces
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2007OBJECTIVE ENGINEERS, INC.
Ballast Stabilization (Use of vibration to control track settlement)
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2007OBJECTIVE ENGINEERS, INC.
Track stabilization worth about 10-20 trains of otherwise slow ordered traffic
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2007OBJECTIVE ENGINEERS, INC.
Thus, the desired vibration lessens chances of this: Lateral Track (Panel) Shift
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2007OBJECTIVE ENGINEERS, INC.
Another potential beneficial use
z From this campus, Dr. Weavers research on rail neutral temperature
zWavelength of high frequency rail vibrations changes with longitudinal stress on the rail
z Goal: Non-destructive determination of rail neutral temperature.
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2007OBJECTIVE ENGINEERS, INC.
RAIL VIBRATION COMPARED TO
OTHER TRANSIT MODES
(Example projects C & D)
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2007OBJECTIVE ENGINEERS, INC.
First some
antique video
footage
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2007OBJECTIVE ENGINEERS, INC.
Moving Cargo, Containers and Operators
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2007OBJECTIVE ENGINEERS, INC.
Evolved from two projects involving weld failures on ISO tank containers
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2007OBJECTIVE ENGINEERS, INC.
Unattended Container Shock Record(Does/does not exceed 4g Design Std?)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-30
-20
-10
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SN 13392 Event 39, Long.
Original extremum value: 20.4
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-10
-5
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Time (sec)
8.6 = extremum after 90 Hz lowpass3.5 = " " 40 Hz "2.5 = " " 30 Hz "1.3 = " " 16 Hz "
-20.4 g raw data?
-2.5g after 30 Hz lowpass filter
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2007OBJECTIVE ENGINEERS, INC.
Well then, this is a much lower frequency event, surely it is abusive
-30.0
-22.5
-15.0
-7.5
0.0
+7.5
+15.0
+22.5
+30.0
0.0 0.1 0.199 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
g
Seconds
g ggX Y Z
Integrating the accel. signal yields a velocity change of 102 mph in 1/3 second. Invalid data!
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2007OBJECTIVE ENGINEERS, INC.
Vibration for many vehicles
compared
(Bob Fries, N.Cooper-rider 1993)
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2007OBJECTIVE ENGINEERS, INC.
TECHNICAL OBSERVATIONSz The highway truck environment is generally more
harsh on cargo & humans than rail. Shipboard environment is generally less harsh than rail. Ship environment is more like a factory floor.
z Low frequencies (
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2007OBJECTIVE ENGINEERS, INC.
Observed & periodic opportunity for engineering confusion
CarModel
+VA
Load Measuring Axle
+Y
+LB+LA +T
+VB
+Z+X
+T
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2007OBJECTIVE ENGINEERS, INC.
Another test risk: small populations
Four strain gages at same locations on cantilever beam next to fixed end.
(22 long, 3 wide,
1/16 thick)
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2007OBJECTIVE ENGINEERS, INC.
Strain variations, even with careful attention to similar gage placement
Time (secs)25.3 25.4 25.5 25.6 25.7
300250200150100500
-50-100-150-200-250
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)
4 gages at 1st bending freq. ~ 3 Hz
300250200150100500-50-100-150-200-250
g
a
g
e
4
(
m
i
c
r
o
s
t
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a
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n
)
13% Variation in
Peak-to-peak
g3 = 543ue
g4 = 502ue
g7 = 477ue
g8 = 521ue
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2007OBJECTIVE ENGINEERS, INC.
What about variations on a railcar?Structural member strains, Left vs. Right
time(secs)245 250 255
-200
-100
0
100
200
300
50% difference in amplitude.
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2007OBJECTIVE ENGINEERS, INC.
Final reminder: accelerations vs. strains
CB_VT_SQBURST.SIF Channel 4
-8-6-4-2024
CB_VT_SQBURST.SIF - Channel 5
-200
-100
0
100
200
300
CB_VT_SQBURST.SIF - Channel 6
time(secs)245 250 255 260 265
-400
-200
0
200
400
600
Low freq. correlation, but not at high freqs.
L
t
.
S
t
r
a
i
n
R
t
.
S
t
r
a
i
n
A
c
c
e
l
.
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2007OBJECTIVE ENGINEERS, INC.
Wrap-up: industry trends relating to S&V
z Perfect engineering specification would fail 100.0% of latent bad designs or processes, while passing 100.0% of the good.
z Actual specifications tended to promote certain dimensional tolerances, minimum design strengths, or perfunctory initial performance not perfect.
z For about a decade, advances in technology have gradually begun to provide operational feedback, largely due to monitoring shock and/or vibration (or close cousins).
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2007OBJECTIVE ENGINEERS, INC.
Implementation risksThis monitoring of S&V (or close cousins) can be
infinitely more complex than the old visual inspection. Thus, there is much concern about the false positives or negatives.
Fortunately, the industry is gradually moving ahead:z Wheel Impact Monitorsz Acoustic Bearing Signaturesz Excessive Railcar Bouncez Peak Wheel Forcesz Yard Coupling Shocks, or desired lack thereofz etc.
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2007OBJECTIVE ENGINEERS, INC.
Two opinions about S&V work in railroading
z PLUS: In an otherwise mature industry, further exploiting shock and vibration to assist business decisions holds great opportunity for rail engineers.
z MINUS: Fostering adoption of these technologies requires great patience and persistence. (Railroads, suppliers, shippers, car owners, and the FRA have a complicated and symbiotic relationship. In some cases, these newer and more effective specifications redistribute costs. This may be unpopular.)
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2007OBJECTIVE ENGINEERS, INC.
Example project E: 1994 brake beam tests. Adoption of standards is still in-process
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2007OBJECTIVE ENGINEERS, INC.
Give an engineer just a simple request
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2007OBJECTIVE ENGINEERS, INC.And the engineer will aim to please
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2007OBJECTIVE ENGINEERS, INC.
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2007OBJECTIVE ENGINEERS, INC.
Engineering Information is not the same thing as test (or analysis) data
Like Dilbert, we need to provide information, not just data, Here is $7.14, you owe
me five & a quarter.