U.S. patent application number 11/724025 was filed with the patent office on 2007-09-20 for system and methods to determine and monitor changes in rail conditions over time.
Invention is credited to Shane M. Farritor, Joseph Alan Turner.
Application Number | 20070214892 11/724025 |
Document ID | / |
Family ID | 38516355 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070214892 |
Kind Code |
A1 |
Turner; Joseph Alan ; et
al. |
September 20, 2007 |
System and methods to determine and monitor changes in rail
conditions over time
Abstract
The present invention is directed to a system and methods with
which changes in rail conditions can be determined and monitored
over time. The present invention includes a database of data,
wherein a first set of data is used for comparison with a second
set of data to determine the stress state of rail.
Inventors: |
Turner; Joseph Alan;
(Lincoln, NE) ; Farritor; Shane M.; (Lincoln,
NE) |
Correspondence
Address: |
VALAUSKAS & PINE LLC
Suite 4130
One North Wacker Drive
Chicago
IL
60606
US
|
Family ID: |
38516355 |
Appl. No.: |
11/724025 |
Filed: |
March 14, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60782608 |
Mar 15, 2006 |
|
|
|
Current U.S.
Class: |
73/602 ; 73/786;
73/862.41 |
Current CPC
Class: |
G01N 29/04 20130101;
G01N 2291/105 20130101; G01N 29/2418 20130101; G01L 1/255 20130101;
G01N 29/4445 20130101; G01N 29/12 20130101; G01N 2291/102 20130101;
B61K 9/08 20130101; G01N 2291/2623 20130101; G01N 2291/02881
20130101 |
Class at
Publication: |
073/602 ;
073/786; 073/862.41 |
International
Class: |
G01N 29/04 20060101
G01N029/04; G01L 5/00 20060101 G01L005/00 |
Claims
1. A system for determining and monitoring stress in rail,
comprising: a signal generator device for generating a signal; a
first energy conversion device coupled to said signal generator
device, said first energy conversion device in response to said
signal generates ultrasonic waves for propagation through the rail;
a second energy conversion device for receiving the ultrasonic
waves propagated trough the rail; a navigation device to determine
position information of the ultrasonic waves at specific time
intervals; an electronic test device for capturing data including
the position information; and a computing device for analyzing the
data in order to calculate ultrasonic wave information and for
comparison to a grouping of ultrasonic wave information to
determine the stress in the rail.
2. The system of claim 1 wherein said signal generator device is a
pulser-receiver.
3. The system of claim 1, wherein said signal generator device is a
laser.
4. The system of claim 1, wherein said first energy conversion
device is a transducer.
5. The system of claim 1, wherein said second energy conversion
device is a receiving transducer.
6. The system of claim 1, wherein said navigation device is a
Global Positioning System.
7. The system of claim 1, wherein said electronic test device is an
oscilloscope.
8. The system of claim 1, wherein said computer device is a laptop
computer.
9. A method for determining and monitoring stress in rail,
comprising: generating a signal; converting the signal to an
ultrasonic sound wave; propagating the ultrasonic sound wave
through the rail; receiving the ultrasonic sound wave; resolving
position information at specific time intervals of the ultrasonic
sound wave; capturing data including the position information at
specific time intervals; storing the data in a database; computing
the data to produce wave speed data; comparing the wave speed data
to a grouping of wave speed data; and detecting longitudinal rail
stress.
10. The method of claim 9, wherein said generating step includes
producing the signal with a signal generator device.
11. The method of claim 9, wherein said converting step includes
producing the ultrasonic sound wave with a first energy conversion
device.
12. The method of claim 9, wherein said receiving step includes
configuring the ultrasonic sound wave with a second energy
conversion device.
13. The method of claim 9, wherein said resolving step includes
determining the position information with the use of a navigation
device.
14. The method of claim 9, wherein said capturing step uses an
electronic test device.
15. The method of claim 9, wherein said computing step uses a
handheld device.
16. The method of claim 9, wherein said comparing step includes an
increase in value of the wave speed data indicating an increase in
longitudinal rail stress.
17. The method of claim 9, wherein said comparing step includes a
decrease in value of the wave speed data indicating a decrease in
longitudinal rail stress.
Description
[0001] This application claims priority of U.S. Provisional
Application No. 60/782,608 filed Mar. 15, 2006.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a system and
methods with which changes in rail conditions, including conditions
related to stress, can be determined and monitored over time. In
particular, the present invention relates to a system and methods
for measuring rail stress over large regions of rail track to
mitigate stress-related issues, such as rail breaks and rail
buckling.
BACKGROUND OF THE INVENTION
[0003] Rail tracks are used on railways, otherwise known as
railroads, which guide trains without the need for steering. As
shown in FIG. 1 rail tracks 20 typically consist of two parallel
rails, 22, 23. Rails are typically made from steel, which can carry
heavier loads than other materials. Rails 22, 23 are laid upon
cross ties 24 that are embedded in ballast 26. Cross ties 24, also
known as sleepers, ensure the proper distance, or gauge, between
the rails 22, 23. Cross ties 24 also distribute the load, or force,
on the rails 22, 23 over the ballast 26. Plates 28 are positioned
on top of cross ties 24 to receive rails 22, 23. The rails 22, 23
are then fastened to the cross ties 24 by a fastener 30, for
example with rail spikes, lag screws, bolts or clips. The fastener
30 is driven through the plate 28 and into the cross tie 24.
[0004] Shown in FIGS. 2 and 3 is a representative rail. Rail 22
consists of rail sections 22', 22'' Rail sections 22', 22'' can be
aligned and secured together by joint bars 32 (FIG. 2) or welding
34 (FIG. 3). Most modern railways use welding to align a secure
rail sections, known as continuous welded rail ("CWR"), to form one
continuous rail that may be several miles long. In this form of
track, the rails are welded together such as by thermite reaction
or flash butt welding.
[0005] Longitudinal stress is a problem over large regions of rail
track. Stress is a measure of force per unit area, typically
expressed in pound-force per square inch (psi). The term,
longitudinal means "along the major (or long) axis" as opposed to
latitudinal which means "along the width", transverse, or
across.
[0006] Longitudinal rail stress ("LRS") is usually related to rail
contractions and expansions, due to changes in temperature.
Longitudinal rail stress leads to failure, which is loss of
load-carrying capacity. Examples of failure include, for example,
buckling and fracture. Rail experiences tensile stress in cold
temperatures, which can lead to fracture or separation of a rail
into two or more pieces. In hot temperatures, rail experiences
compression stress, which can lead to buckling or warping. Tensile
stress is stress state causing expansion (increase in volume) where
as compression stress is stress state causing compaction (decrease
in volume). It should be noted that a zero stress state is when the
material does not experience any stress. Failures, among other
things, cause derailments and service disruption.
[0007] The ability to measure longitudinal rail stress is a primary
challenge in the railway industry. The presence of large regions of
rail track reduces the ability of rail to expand and contract
easily due to daily and seasonal temperature changes. Thus, high
longitudinal stresses can develop, which in turn leads to possible
failure.
[0008] In the United States, from years 2001-2003, there were over
98 derailments associated with track buckling. Damage estimates for
these derailments exceed $37 million. In addition, over 900
additional incidents associated with rail stress were reported. LRS
is an on-going major difficulty for railroads.
[0009] There has been extensive research to develop a
non-destructive method to measure LRS. Current techniques include
strain gauges (e.g., available from Salient Systems) and rail
uplift (e.g., the VERSE system by Vortok, Inc.). There are
downfalls to these current techniques. Strain gauges only provide
measurements related to stress in a local, or confined, area.
Additionally, strain gauges present difficulty in determining the
zero stress state. Measurement by rail uplift is costly and
requires a section of rail to be detached from the ties. Techniques
such as these are single-point measurements making it difficult to
obtain measurements on large regions of rail track.
[0010] There is a demand therefore, for reliable, practical and
cost effective system and methods with which changes in rail
conditions can be determined and monitored over time, including
conditions related to longitudinal rail stress. The present
invention satisfies that demand.
SUMMARY OF THE INVENTION
[0011] For purposes of this application, the present invention is
discussed in reference to rail tracks on railways, but the present
invention is applicable to any structure, including geological
structures. For example, the present invention can determine and
monitor changes in conditions of buildings, bridges, fault lines
for predicting earthquakes and land mass for prospecting oil.
[0012] The present invention is directed to a system and methods
with which changes in rail conditions can be determined and
monitored over time. In the broadest form, the present invention
includes a signal generator device, an energy conversion device, an
electronic test device, a database, a computing device, and a
navigation device.
[0013] The present invention includes a signal generator device
that is useful to non-destructively assess material conditions in
rail. One embodiment of a signal generator device is a
pulser-receiver. A pulser-receiver includes a pulser that generates
electrical signals, and thereby ultrasonic sound waves, and a
receiver to receive them. Another signal generator device includes
a laser, which generates heat creating an ultrasonic sound
wave.
[0014] An energy conversion device converts signals from one form
to another. One such type of energy conversion device is a
transducer, which includes such types as electromagnetic,
electrochemical, electromechanical, electroacoustic, photoelectric,
electrostatic, or thermoelectric. Transducers typically communicate
from a transducer to a receiving transducer.
[0015] One embodiment of the invention includes a system and
methods wherein the energy conversion device is securable to the
rail track of a railway.
[0016] Another embodiment of the invention includes a system and
methods in which the energy conversion device is securable to the
wheels of a railway car to implement a "rolling" system. A
"rolling" system allows the present invention to become mobile,
thereby allowing rail conditions to be determined and monitored
over large regions of rail track. It is further contemplated that a
"rolling" system can be integrated with other rail measurement
techniques, such as the rail deflection system developed by Shane
Farritor, or defect detection vehicles, such as those used by
Sperry Rail Service or Herzog Services, for example.
[0017] An electronic test device captures data, such as voltage,
current, ultrasonic wave information, temperature, date, time,
position, or any measurement to name a few. Such equipment may
include a voltmeter, ohmmeter, ammeter, power supply, signal
generator, pulse generator, oscilloscope and frequency counter, for
example. Ultrasonic wave information can include speed, amplitude,
and wavelength
[0018] The present invention also includes a database for the
storage of a grouping of data. A grouping of data can include one
or more sets of data. One or more sets of data can be compared with
one or more sets of data, as well as utilized for various
calculations. For example, a first set of data can be compared with
a second set of data. Likewise, data can be computed and analyzed,
for example to determine the stress state of rail. The database can
be retained on the computer used to conduct much of the analyses or
on a separate computer or on a computing device.
[0019] A computing device is a machine for manipulating data
according to a list of instructions. For example, a computer can be
a laptop computer, handheld device, or personal digital
assistant.
[0020] A navigation device is a device with position, or location,
capability, such as a Global Positioning System ("GPS").
[0021] The improved system and methods of the present invention
permit changes in rail conditions, most specifically longitudinal
rail stress to be assessed and monitored over time dynamically and
non-destructively. One embodiment of the system includes a signal
generator device that generates a signal that is transmitted to an
energy conversion device. The energy conversion device converts the
signal to a sound wave that propagates through the rail to a
receiving energy conversion device. The navigation device
determines position of the sound wave at specific time intervals.
An electronic test device captures this data, and stores the data
to a database. The computing device processes the data pertaining
to position of the sound wave at specific time intervals to compute
wave speed. The wave speed at specific intervals of time as a
function of position is also stored in the database for comparison
to previous or subsequent data to determine and monitor changes in
rail conditions.
[0022] According to the present invention, increasing wave speeds
indicates an increase in longitudinal rail stress potentially
leading to rail breaks while decreasing wave speeds indicates a
decrease in longitudinal rail stress potentially leading to rail
buckling.
[0023] The present invention has an objective of providing a system
and methods to determine and monitor changes in rail conditions,
including conditions related to stress.
[0024] Another object of the present invention is to measure rail
stress over large regions of rail track to mitigate stress-related
issues, such as fractures and buckling.
[0025] The present invention increases rail track safety by
predicting failures before they occur.
[0026] Another object of the present invention is to provide a
system and method for rail track maintenance.
[0027] While current technology is focused on single-position
measurements; the present invention provides multiple position
measurements of stress in rail.
[0028] Another object of the present invention is to provide a
database for mass storage of data. The database can be accessed for
analysis of the data including various calculations to determine
and monitor changes in rail conditions over time.
[0029] Another object of the present invention is to utilize a
navigation system to accurately determine position of the
failure.
[0030] These and other advantages, as well as the invention itself,
will become apparent in the details of construction and operation
as more fully described and claimed below. Moreover, it should be
appreciated that several aspects of the invention can be used in
other applications where monitoring of stress would be
desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 illustrates rail tracks;
[0032] FIG. 2 illustrates rail tracks aligned and secured together
by joint bars;
[0033] FIG. 3 illustrates rail tracks aligned and secured together
by welding;
[0034] FIG. 4 is a flow chart for determining and monitoring stress
in rail according to the present invention;
[0035] FIG. 5 illustrates a system for determining and monitoring
stress in rail according to the present invention; and
[0036] FIG. 6 illustrates the measurements taken from the system of
FIG. 5.
DETAILED DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT
[0037] The present invention will now be described in detail with
reference to certain embodiments thereof as illustrated in the
accompanying drawings. In the following description, numerous
specific details are set forth in order to provide a thorough
understanding of the present invention and how it may be applied.
It will be apparent, however, to one skilled in the art, that the
present invention may be practiced without some or all of these
specific details. In other instances, well-known process steps
and/or structures have not been described in detail to prevent
unnecessarily obscuring the present invention.
[0038] An embodiment of the system and methods of the present
invention are illustrated as a flow chart 100 in FIG. 4. In this
embodiment, a pulser-receiver 110 generates an electrical signal
that is transmitted 113 to a transducer 122. The transducer 122
converts the electrical signal to an ultrasonic wave 115 that
propagates through the rail to a receiving transducer 124.
Ultrasonic refers to sound with a frequency greater than 20
kilohertz. The GPS 130 determines position of the sound wave 115 at
specific time intervals. An oscilloscope 140 captures measurements
of data transmitted 117, such as ultrasonic wave information,
temperature, date, time, and position, and provides the data via
transmission 119 to the computer 150 for processing. The computer
150 can further include a database 160 for storage of the data.
[0039] In another embodiment, a laser is used to generate a signal
by firing the laser at a rail, thereby generating heat and an
ultrasonic wave which may be picked up by a receiving transducer
124.
[0040] The computer 150 includes an autocorrelation component 152
by which the travel time of the ultrasonic wave may be calculated.
The travel time is then used to calculate the ultrasonic wave
speed, which is then correlated to longitudinal rail stress. If the
initial electrical signal generated from the transducer 122
includes a set of voltages V.sub.i at times t.sub.i, then the
autocorrelation formula is defined as: r k = i = 1 N - k .times. (
V i - V _ ) .times. ( V i + k - V _ ) i = 1 N .times. ( V i - V _ )
2 , .times. where ##EQU1## V _ = 1 N .times. i = 1 N .times. V i .
##EQU1.2##
[0041] Maxima in the vector r determines the travel times,
otherwise referred to herein as the speed, of the ultrasonic wave.
The travel times are dictated by the peak(s) of the ultrasonic wave
(see FIG. 6). These travel times are stored in the database 160 and
used for comparison with other measurements (past or
subsequent).
[0042] The computer utilizes the autocorrelation formula to
calculate the wave speed of the ultrasonic sound wave. The wave
speed is calculated by dividing transducer separation distance by
the travel time of the sound wave. This wave speed data, along with
other data such as temperature, date, time, and position of the
sound wave at specific intervals determined by the navigation
device, are stored onto a database 160.
[0043] The data stored within the database 160 includes wave speed
at specific intervals of time as a function of position. This data
is compared to a grouping of data stored within the database 160 to
determine and monitor changes in rail conditions. Changes in wave
speed can be attributed to changes in LRS.
[0044] FIG. 5 illustrates an embodiment of a system 200 for
determining and monitoring stress in rails according to the present
invention. A transducer 122 and receiving transducer 124 are sized
and shaped such that each may be positioned on a surface of the
rail 25 such as a side surface 25A, or top surface 25B of a rail 25
through an applicator 27. The applicator 27 may be in the form of a
wedge 27 or other shape to permit easy adherence to the rail
surface 25A, 25B. The applicator 27 is preferably formed of a
material to facilitate the transmission of the ultrasonic wave by
the transducer 122 and the receptor of the ultrasonic wave by the
receiving transducer 124. Acrylic is one of the many materials that
may be sued for this purpose. Other embodiments of the system and
methods utilize the positioning of the transducers 122, 124 on the
wheels of a railway car.
[0045] An ultrasonic pulser-receiver 110 sends a voltage signal to
the transducer 122. The transducer 122 converts the voltage signal
to an ultrasonic sound wave that propagates through the rail 25 to
the receiving transducer 124. The receiving transducer 124 and
amplifies and digitizes the sound wave into signals. The signals
from the receiving transducer 124 may be acquired such as with an
oscilloscope 140, and conveyed to a database, for example within a
laptop or equivalent computer (not shown). The database is used for
data analysis of the signals. The computer utilizes an
autocorrelation formula to calculate the travel time of the sound
wave. The wave speed is then calculated by dividing transducer
separation distance by the travel time of the sound wave.
[0046] This wave speed data, along with other data such as
temperature, date, time, and position of the sound wave at specific
intervals determined by the navigation device, are stored onto a
database. Data such as temperature can be taken by the transducers
122, 124 on the rail 25. Likewise, the navigation device (not
shown) can take the position data where the temperature data is
taken.
[0047] The database 160 stores the data, including wave speed at
specific intervals of time as a function of position. The database
160 can be on the computer 150 or on a separate computer.
[0048] The computer 150 compares data of the database 160. A first
set of data can be compared to other sets of data. The first set of
data can be one data point, a plurality of data points, a base line
or control data points. A second set of data points can be one data
point or a plurality of data points for comparison with the first
set of data points. The comparison between data points determines
abnormalities or changes, if any, between the data over time.
[0049] According to the present invention, a first set of data
points, such as wave information, is compared to a second set of
data points. A comparison resulting in an increase in wave speeds
indicates an increase in longitudinal rail stress potentially
leading to rail breaks while a comparison resulting in a decrease
in wave speeds indicates a decrease in longitudinal rail stress
potentially leading to rail buckling.
[0050] Ultrasonic wave speed at specific time intervals as a
function of position in graphically illustrated in FIG. 6.
[0051] While endeavoring in the foregoing specification to draw
attention to those features of the invention believed to be of
particular importance it should be understood that the Applicants
claim protection in respect of any patentable feature or
combination of features hereinbefore referred to and/or shown in
the drawings whether or not particular emphasis has been placed
thereon. While the apparatus and method herein disclosed forms a
preferred embodiment of this invention, this invention is not
limited to that specific apparatus and method, and changes can be
made therein without departing from the scope of this invention,
which is defined in the appended claims.
[0052] Therefore, the foregoing is considered as illustrative only
of the principles of the invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and operation shown and described, and accordingly,
all suitable modifications and equivalents may be resorted to,
falling within the scope of the invention.
* * * * *