“Non-destructive in-place condition assessment ...
Transcript of “Non-destructive in-place condition assessment ...
Sponsored by
William W. Hay Railroad Engineering Seminar
“Non-destructive in-place condition assessment technologies for deterioration in railroad ties”
John PopovicsAssociate Professor University of Illinois at Urbana-Champaign
Date: Friday, February 27, 2015 Time: Seminar Begins 12:20
Location: Newmark Lab, Yeh Center, Room 2311University of Illinois at Urbana-Champaign
John S. PopovicsThe University of Illinois at Urbana-Champaign
RailTEC Hay SeminarFebruary 27, 2015
NON-DESTRUCTIVE IN-PLACE CONDITION ASSESSMENT TECHNOLOGIES FOR DETERIORATION IN RAILROAD TIES
Presentation outline
1) Objective, motivation, review of previous
work
2) Development of data analysis/evaluation
schemes
3) Improvement of ultrasonic testing set-up
4) Experimental results
5) Future Work
3
Motivation
Concrete and timber crossties are important components in the rail bed structure:
* Distribute wheel loads (Support)* Maintain track geometry (Stability)* Electrically isolate rails (Isolation)
<J.R. Edwards>
Material integrity of ties especially important for high speed rail structures
4
Vision for ultrasonic evaluation of rail ties
Concept of implementation for performing cost effective inspection: one-sided, air-coupled ultrasound techniques
carried out from a moving platform
5
Timber rail ties have long been used in rail structures in the US. Structural deficiency arises from natural degradation mechanisms
Deteriorated wood Sound wood
6
A variety of damage
mechanisms can
compromise concrete ties
Microcracks
Delamination
Rail seat deterioration(RSD)
<Walker et al. 2006>
<S. Naar>
<J.R. Edwards>
Concrete rail ties are becoming more prevalent, but can suffer deterioration
Mechanical body waves in solids: P-waves
Direction of Travel
Excitation
Direction of Particle Motion
also: Longitudinal (L-) Waves, Compression Waves
( )( )( )2ν1ν1ρ
ν1EvP −+−
=
Wave Velocity: Governing ParametersYoung’s Modulus EPoisson’s Ratio vDensity ρ
<T. Voigt >
Mechanical body waves in solids: S-waves
Direction of Travel Direction of Particle Motion
Wave Velocity in solids: Governing Parameters
Shear Modulus GDensity ρ
no propagation in liquids or gases !
also: Transverse (T-) Waves, Shear Waves
Excitation
ρGvS =
<T. Voigt >
VP > VS in all known solids
Guided waves: Surface waves
<www.lamit.ro/earthquake-early-warning-system.htm>
Rayleigh surface wave travels along free surface but do not propagate far into the body of the material. Rayleigh waves travel slightly slower than shear waves, and
show coupled longitudinal and shear motion
Guided waves: Lamb waves in plates
<N. Ryden>
Lamb wave are set up in large plates
Multiple (infinite) modes of propagation, with varying motion character and propagation velocity
Can be visualized as a propagating resonance
Increasing frequency or plate thickness
Surface guided wave
Contactless MEMSReceiver
Contactless electrostaticSender
Fully contactless ultrasonic technique
AirConcrete
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2 3 4
x 10-4
-0.01
-0.005
0
0.005
0.01A
mpl
itude
(V)
Time(sec)
MEMS 1 at same locationMEMS 2 at same location
Key feature of contactless sensing: 1) Signal consistency
1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
Am
plitu
de(V
)
Time(sec)
1st Try with same Accelerometer2nd Try with same Accelerometer3rd Try with same Accelerometer
0 1 2 3 4 5 6
x 10-4
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
Am
plitu
de(V
)
Time(sec)
AccelerometerMEMS SensorCondensor MicrophoneDynamic Microphone
Accelerometer(contact)
Smooth
Medium
Extremely Rough
Distance
0 1 2 3 4 5 6 7
x 10-4
-0.4
-0.2
0
0.2
0.4
0.6
Ampl
itude
(V)
Time(sec)
0 1 2 3 4 5 6 7
x 10-4
-0.4
-0.2
0
0.2
0.4
0.6
Am
plitu
de(V
)
Time(sec)
0 1 2 3 4 5 6 7
x 10-4
-0.4
-0.2
0
0.2
0.4
0.6
Ampli
tude
(V)
Time(sec)
Key feature of contactless sensing: 2) Application to rough surfaces
Development of data analysis/evaluation
schemes
Ultrasonic surface wave data scans reveal that signal velocity and
attenuation indicate presence of distributed damage
Amplitude (v)
Wave arrivals
Forward propagating
energy attenuation
0 % 0.6 %0.3 %100 150 200 250 300
0.5
1
1.5
2
x 10-12
Location or distance (mm)
Area
of a
mpl
itude
2 (on
ly th
ree
peak
s)
zero0.30.6
Most attenuated
Characterization of forward propagating signal energy through short-time-interval computation
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-3
-2
-1
0
1
2
3
x 10-3
Time(sec)
ampl
itude
(V)
A short-time-interval average signal a window width equal to the duration of the excitation pulse, of the square of the filtered signal was then constructed
(Weaver & Sachse, 1995).
Δt
1 1.5 2 2.5 3 3.5 4 4.5
x 10-4
-11
-10
-9
-8
-7
-6
-5
Time(sec)ln
(E)
x 160mm
1 1.5 2 2.5 3 3.5 4 4.5
x 10-4
-11
-10
-9
-8
-7
-6
-5
Time(sec)ln
(E)
x 160mm
Shifting of energy envelope indicates energy dissipation from wave scattering
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2
x 10-4
-10
-9.5
-9
-8.5
-8
-7.5
-7
-6.5
-6
Time(sec)
ln(E
)
x 160mm
0 %0.3 %0.6 %
Wave scattering
The reflection of ultrasonic energy away from the original direction of propagation; caused by reflection, refraction and mode conversion from internal
inclusions. Causes signal loss, signal dispersion and scattering “noise”
Detected back-scattered signal
<Oelze 2007>
Can we make use of ultrasonic backscatter measurements to characterize distributed damage in
concrete using surface waves?
10mm
MEMS array
Transmitter
baffle
coherent
12
3
45
6
7
backscattering
coherent
Incoherent (backscattering )
Concrete samples subjected to sets of repeated hot-cold and wet-dry cycles to impart distributed damage
Ultrasonic backscatter and resonant frequency data for concrete samples subjected to many damage cycles
Standard resonance frequencyUT Backscattering variance
68o to ice 80o to ice
120o (dry) to 23o (wet)
Symmetric Lamb
Anti-symmetric Lamb
A0
A1
S0
S1 A2S2
Delamination(defect)
Concrete
Fast MASW
Air-coupled ultrasonic approach to detectdelamination in concrete ties using Lamb waves
<S. Naar>
20 - 100 mm
Improvement of ultrasonic testing set-up
Improved ultrasonic pulse control enables empowered test schemes and data analysis approaches
We have improved output amplitude, voltage biasing control, signal to noise ratio and frequency and bandwidth control of input signal for the transmitting transducer
o Center frequency control between 10-90 kHz
o Improved pulse duration and shape control: chirp and tone burst signals now possible
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Ultrasonic hardware developments
Impr
oved
sen
sor
desi
gn
Crosshair Laser targeting
Contactless capacitance transducer Micro processer
Signal process
Gyro tilt sensor
Contactless sensor bracket
Adjustable height
Contactless MEMS sensor
Scan
ning
sys
tem
s
Increased offset distance between sensors and rail tie is critical for practical application: at least 20 cm (8 inch) offset needed
35mm 10mm
81mm0 0.5 1 1.5 2 2.5
x 10-3
-3
-2
-1
0
1
2
3x 10-3
Time(sec)
Am
plitu
de(V
)
4 5 6 7 8 9 10 11 12
x 10-4
-1
0
1
x 10-4
Time(sec)
Am
plitu
de(V
)
Direct acoustic wave
Surface wave
Surface wave
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Increased transmitter and receiver offsets yield good surface wave signal. However large lateral spacing may require
modification of signal analysis schemes
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2
x 10-3
-5
0
5
x 10-5
Time(sec)
Am
plitu
de(V
)
200mm
200
mm
200
mm
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Experimental Results
Optimal (for concrete) air-coupled configuration applied to samples from timber ties. Contact sensor used for comparison
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Ultrasonic signals from sound timber across varying distance. 100 times averaging used. Both P-waves and surface waves readily generated in timber.
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-5
0
5x 10
-3
ampl
itude
(V)
time(sec)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-5
0
5x 10
-3
ampl
itude
(V)
time(sec)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-5
0
5x 10
-3
ampl
itude
(V)
time(sec)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-5
0
5x 10
-3
ampl
itude
(V)
time(sec)
MicrophoneAcelerometer
4166.6 m/s: P-wave
1388.8 m/s:Surface wave
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0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-2
0
2x 10
-3
ampl
itude
(V)
50mm
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-4
-2
0
2x 10
-3
ampl
itude
(V)
100mm
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-4
-2
0
2x 10
-3
ampl
itude
(V)
150mm
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 10-4
-4
-2
0
2x 10
-3
ampl
itude
(V)
200mm
microphoneacellerometer
4054.1 m/s
1369.8 m/s
Ultrasonic signals from deteriorated timber across varying distance. 100 times averaging used. Both P-waves and surface waves show distinction of material quality.
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The goal is to develop understanding of inter-relation between damage and surface wave behavior
Detection of rail seat damage (RSD) in concrete ties
Rail seat deterioration (RSD)
Concrete crossties are important
components
• Distribute wheel loads (Support)
• Maintain track geometry (Stability)
• Electrically isolate rails (Isolation)
Zeman,2010
degradation at contact interface between the concrete rail seat and the rail pad that can result in track geometry problems
Currently, freeze-thaw cracking, crushing, hydro-abrasive erosion, and hydraulic pressure cracking may contribute to RSD
Zeman,2010
Preliminary RSD testing configuration: small offset
Receiver array
Sender
R1 : no damage R2 : moderate RSD R3 : serious RSD
Test results with and without a bearing pad
2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5
x 10-4
-8
-6
-4
-2
0
2
4
6
8x 10-3
Time(sec)
Ampl
itude
(V)
NoPadSerious RSD damage
2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5
x 10-4
-8
-6
-4
-2
0
2
4
6
8x 10-3
Time(sec)
Ampl
itude
(V)
NoPad
Moderate RSD damage
2.8 3 3.2 3.4 3.6 3.8 4 4.2
x 10-4
-4
-3
-2
-1
0
1
2
3
4x 10-4
Time(sec)
Am
plitu
de(V
)
r0r1r2
r1r2r3
R1 R2 R3
Are individual signal data reliable?
r1r2r3
Integrated signal energy analysis
Spatially averaged signals from multi-sensor array
Savr t =1
𝑁𝑁𝑝𝑝𝑝𝑝𝑝𝑝𝑝�y=1
𝑁𝑁𝑝𝑝𝑝𝑝𝑝𝑝𝑝
Tavr_y t
Statistical analysis for inhomogeneous material
Array averaged = Group = position, p1, p2….
In total seventy signal of each damage region
2 3 4
x 10-4
-16
-15
-14
-13
-12
-11
Time(sec)
ln(E
)
region =3, position =10
Quantification and statistical interpretation
averaged data on position-1 has 7 signals
So, a Box plot hasseven array signals
Area
of l
n(E)
2 3 4
x 10-4
-16
-15.5
-15
-14.5
-14
-13.5
-13
-12.5
-12
-11.5
-11
Time(sec)
ln(E
)2
region =3, position =1
12345678910
10 different positions
-2400
-2300
-2200
-2100
-2000
-1900
1 2 3 4 5 6 7 8 9 10Position
area
of ln
(E)2
range from =0.002s, to =0.0035s
Area
of l
n(E)
ln(E
)
Statistical interpretation of test data shows distinction only of most severe RSD damage
-2400
-2300
-2200
-2100
-2000
-1900
1 2 3 4 5 6 7 8 9 10Position
area
of l
n(E
)2
range from =0.002s, to =0.0035s
-2400
-2300
-2200
-2100
-2000
-1900
1 2 3 4 5 6 7 8 9 10Position
area
of l
n(E
)2
range from =0.002s, to =0.0035s
-2400
-2300
-2200
-2100
-2000
-1900
1 2 3 4 5 6 7 8 9 10Position
area
of l
n(E
)2
range from =0.002s, to =0.0035s
R1 R2 R3
Solid
Rough 1
Rough 2
Follow on RSD testing configuration: large offset
Testing configuration
250 mm250 mm
Ultrasonic ray paths and sensor configuration
Path 1
Path 2
Path 3
Seven different MEMS receivers
1
2
3
4
5
6
7
Energy envelope data collected along path 1 shows clear distinction between damage extent levels
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
x 10-3
-10.5
-10
-9.5
-9
-8.5
Time(sec)
ln(E
)
solidrough1rough2
1.2 1.3 1.4 1.5 1.6 1.7 1.8
x 10-3
-11.5
-11
-10.5
-10
-9.5
-9
-8.5
-8
Time(sec)
ln(E
)
solidrough1rough2
Raw energy envelope data Envelope data with diffusion fits
Future work
Optimize data analysis/evaluation schemes
Test prototype development and evaluation
Develop schemes to target tie regions rather than specific defects, providing overall tie heath index
Incorporate hardware in moving test platform
Evaluate on in-place ties
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Acknowledgments
This research is carried out with the help of support from the Association of American Railroads (AAR), Technology Scanning Program
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