Dynamic rail longitudinal stress measuring system

• US 5,386,727 A
• Filed: 03/03/1993
• Issued: 02/07/1995
• Est. Priority Date: 06/02/1992
• Status: Expired due to Fees

• Current Assignee: Herzog Contracting
• Original Assignee: Herzog Contracting
• Inventors: Searle, Donald S.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Finley, Rose M.
• Application Number:
  US08/025,937
• Time in Patent Office: 706 Days
• Field of Search: 73/597, 73/599, 73/602, 73/624, 73/625, 73/627, 73/628, 73/636, 73/639, 73/635, 73/641, 73/642
• US Class Current: 73/602
• CPC Class Codes: G01L 1/255 using acoustic waves, or acoustic emission G01L1/10 and G01L1/16 take precedence
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/103 one emitter, two or more receivers
• CPC Class Codes: G01N 2291/262 Linear objects
• CPC Class Codes: G01N 2291/2623 Rails; Railroads
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/0618 synchronised with scanning, e.g. in real-time
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/2412 using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18
• CPC Class Codes: G01N 29/2468 Probes with delay lines
• CPC Class Codes: G01N 29/2493 Wheel shaped probes
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: G01N 29/326 compensating for temperature variations
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

A system and method for dynamically and non-destructively measuring the longitudinal stresses in a rail of a continuous rail track includes an ultrasonic transmitter which transmits a signature coded pulse pattern through a rail which pulse pattern is altered by the rail section dependent upon the longitudinal stress within the rail. The altered pulse pattern is then received and a data processor, in conjunction with a rail height detector, a rail temperature detector, and a rail splice detector, dynamically determines the longitudinal stresses in the rail as a function of the received pulse characteristics and calculates the stress free temperature (SFT) of the rail. A rail marker marks portions of the rail having unacceptable SFT values. Stress and related rail data are recorded on a data log. A position sensor provides milepost positions to three decimal places.

Claims

1. An apparatus for measuring the longitudinal stress in a section of railroad rail, comprising:

(a) transmitting means for transmitting an ultrasonic signature signal into said section of rail;

(b) receiving means spaced from said transmitting means for receiving the transmitted ultrasonic signature signal from said section of rail, said received signature signal having been altered by said rail section depending upon the longitudinal stress within said rail section;

(c) means for processing the altered ultrasonic signature signal to generate a variable dependent upon the longitudinal stress in said rail section; and

(d) means for calculating the longitudinal stress in the rail section based upon said generated variable.

2. An apparatus as in claim 1, and further including:

(a) a vehicle for moving said apparatus along said rail, said apparatus making repeated measurements of longitudinal stress at different testing points within each of multiple rail sections of said rail.

3. An apparatus as in claim 2, and further including:

(a) a rail temperature detector for detecting the temperature of said rail.

4. An apparatus as in claim 3, wherein:

(a) said rail temperature detector utilizes infrared measuring techniques.

5. An apparatus as in claim 3, and further including:

(a) a rail height detector for continuously determining the height of said rail.

6. An apparatus as in claim 5, wherein:

(a) said rail height detector includes an ultrasonic transmitter and detector.

7. An apparatus as in claim 5, and further including:

(a) a rail position detector for continuously determining the position of said apparatus along said rail.

8. An apparatus as in claim 7, wherein:

(a) said calculating means further includes means for calculating the stress free temperature of said rail section at each testing point.

9. An apparatus as in claim 8, and further comprising:

(a) means for maintaining a continuous log of rail conditions as said apparatus is moved along said rail section.

10. An apparatus as in claim 9, wherein:

(a) said log includes one or more of the following;

(i) longitudinal rail stress;

(ii) rail stress free temperature;

(iii) rail temperature;

(iv) rail height;

(v) rail position; and

(vi) rail events such as crossings, curves, rail boundaries, etc.

11. An apparatus as in claim 2, wherein:

(a) said transmitting means transmits a series of ultrasonic signature signals, each ultrasonic signature signal being composed of a plurality of ultrasonic pulses; and

(b) said processing means generates said variable from a measured differential pulse transit time between selected pulses of at least two different signature signals in said series.

12. An apparatus as in claim 11, wherein:

(a) said receiving means comprises at least one sensor spaced from said transmitting means along said rail.

13. An apparatus as in claim 12, wherein:

(a) the spacing of said at least one sensor from said transmitting means is variable.

14. An apparatus as in claim 12, wherein:

(a) said receiving means comprises noise suppression means for suppressing extraneous signals not related to said signature series.

15. An apparatus as in claim 12, wherein said transmitting means comprises:

(a) an ultrasonic generator means; and

(b) a wheel containing said generator means, said wheel being in contact with said rail and being filled with a fluid adapted to provide a reliable conduction medium for said ultrasonic signals from said generator means into said rail section.

16. An apparatus as in claim 1, wherein:

(a) said transmitting means and said receiving means are contained at either end of an elongate portable, hand-held frame; and

(b) said frame is adjustable lengthwise such that the spacing between said transmitting means and said receiving means can be varied.

17. An apparatus as in claim 16, wherein:

(a) said hand-held frame comprises means for attaching said apparatus to said rail section.

18. An apparatus as in claim 17, wherein:

(a) said means for attaching said apparatus to said rail section includes a surface which can be selectively magnetized and demagnetized.

19. An apparatus as in claim 16, wherein:

(a) said apparatus further includes a rail temperature sensor.

20. An apparatus as in claim 16, wherein:

(a) said processing means and said calculating means are removably attachable to said transmitting means and said receiving means.

21. An apparatus as in claim 16, wherein:

(a) said transmitting means transmits a series of ultrasonic signature signals, each signature signal being composed of a plurality of ultrasonic pulses; and

(b) said processing means generates said variable from the differential transit time between selected pulses of at least two different signals of said series which reaches said receiving means.

22. An apparatus as in claim 16, wherein:

(a) said transmitting means transmits a series of signature pulses into said rail section; and

(b) said processing means generates said variable from the number of pulses reaching said receiving means.

23. An apparatus as in claim 16, wherein:

(a) said transmitting means transmits a series of ultrasonic waves into said rail; and

(b) said processing means generates said variable from the amplitude of one or more of the waves reaching said receiving means.

24. An apparatus for dynamically measuring the longitudinal stress in a section of railroad rail, comprising:

(a) transmitting means for transmitting a series of ultrasonic signature signals into said section of rail;

(b) receiving means spaced from said transmitting means for receiving the transmitted ultrasonic signature signals from said section of rail, said received signature signals having been altered by said rail section depending upon the longitudinal stress within said rail section;

(c) means for processing the received, altered ultrasonic signature signals to generate a variable dependent upon the longitudinal stress in said rail section, said variable being determined from said alteration of said signature signals;

(d) means for calculating the longitudinal stress in the tested rail section based upon said generated variable; and

(e) a vehicle for moving said apparatus along said rail, said apparatus making repeated measurements of longitudinal stress within each section of said railroad rail as said vehicle moves along the rail.

25. An apparatus as in claim 24, and further including:

(a) a rail temperature detector for detecting the temperature of said rail.

26. An apparatus as in claim 25, and further including:

(a) a rail height detector for continuously determining the height of said rail.

27. An apparatus as in claim 26, and further including:

(a) a rail position detector for continuously determining the position of said apparatus along said rail.

28. An apparatus as in claim 27, and further including:

(a) means for maintaining a continuous log of rail conditions as said apparatus is moved along said rail.

29. An apparatus as in claim 28, wherein:

(a) said log includes one or more of the following;

(i) longitudinal rail stress;

(ii) rail stress free temperature;

(iii) rail temperature;

(iv) rail height;

(v) rail position; and

(vi) rail events such as crossings, curves, rail boundaries, etc.

30. An apparatus as in claim 24, wherein:

(a) the spacing of said receiving means from said transmitting means is variable.

31. An apparatus as in claim 24, wherein:

(a) said receiving means comprises noise suppression means for suppressing extraneous signals not related to said signature series.

32. An apparatus as in claim 24, wherein:

(a) each of said ultrasonic signature signals is composed of a plurality of ultrasonic pulses; and

(b) said processing means generates said variable from a measured differential pulse transit time between selected pulses of at least two different signature signals in said series.

33. An apparatus as in claim 24, wherein:

(a) each of said ultrasonic signature signals is composed of a plurality of ultrasonic pulses; and

(b) said processing means generates said variable from the number of pulses reaching said receiving means.

34. An apparatus as in claim 24, wherein:

(a) each of said ultrasonic signature signals is composed of at least one ultrasonic wave; and

(b) said processing means generates said variable from the amplitude of one or more of the waves reaching said receiving means.

35. A method of determining the longitudinal stress in a section of railroad rail, comprising the steps of:

(a) transmitting a series of ultrasonic signature signals into said rail at a point in said rail section;

(b) receiving said ultrasonic signature signals from said rail at another point in said rail section, said received signature signals having been altered by said rail section depending upon the longitudinal stress within said rail section;

(c) processing said received altered signals to yield a variable dependent upon the alteration of said signature signals by said longitudinal stress within said rail section; and

(d) calculating said longitudinal stress based upon said variable.

36. A method as in claim 35, and further comprising the steps of:

(a) detecting the temperature within said rail section;

(b) detecting the rail height of said rail section; and

(c) using said rail temperature, said rail height and said calculated stress to calculate the stress free temperature of said rail section.

37. A method as in claim 35, and further comprising the steps of:

(a) repeatedly transmitting and receiving said signals while moving said points at which said signature signal series transmitted and received;

whereby

(b) said longitudinal stress and said stressfree temperature are repeatedly calculated for the entire length of said rail section.

38. A method as in claim 37, and further comprising the step of:

(a) maintaining a log of rail conditions as said transmitting and receiving points are moved.

39. A method as in claim 36, and further comprising the steps of:

(a) using said rail height to adjust the distance between the point at which said signature series signal is transmitted and the point at which said series is received.

40. A method as in claim 35, wherein:

(a) each of said ultrasonic signature signals comprises a plurality of ultrasonic pulses; and

(b) said variable is generated from a measured differential pulse transit time between selected pulses of at least two different ultrasonic signature signals in said series.

41. A method as in claim 35, wherein:

(a) each of said ultrasonic signature signals comprises a plurality of ultrasonic pulses; and

(b) said variable is generated from the number of received pulses.

42. A method as in claim 35, wherein:

(a) each of said ultrasonic signature signals comprises a plurality of ultrasonic waves; and

(b) said variable is generated from the amplitude of one or more of the received waves.

43. A method as in claim 35, and further comprising:

(a) initially transmitting and receiving said series along a length of stress free rail to provide a base value for said variable.