Method for determining the wall thickness and the speed of sound in a tube from reflected and transmitted ultrasound pulses
First Claim
1. A method of determining the wall thickness of a tubular workpiece and the speed of sound within said tubular workpiece from a single set of measured time of flight data, said method comprising the steps of:
- configuring an acoustic couplant medium;
defining a transmission path in said acoustic couplant medium;
selectively disposing said tubular workpiece in said acoustic couplant medium such that said tubular workpiece is in said transmission path;
defining, along said transmission path, an acoustic discontinuity at each interface between a surface of said tubular workpiece and said acoustic couplant medium;
transmitting a plurality of ultrasonic waves through said transmission path, at least one of said plurality of ultrasonic waves being transmitted without the presence of said tubular workpiece in said transmission path;
receiving signals corresponding to;
said plurality of transmitted ultrasonic waves that are reflected from at least one of said acoustic discontinuities; and
said plurality of transmitted ultrasonic waves that traverse the substantial entirety of said transmission path;
measuring time of flight data for each of said received signals;
calculating a speed of sound in said tubular workpiece based on said measured time of flight data; and
calculating a thickness of each wall of said tubular workpiece based on said measured time of flight data and said calculated speed of sound.
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Accused Products
Abstract
A method for the determining ultrasonic sound propagation speed and wall thickness of a tubular object. Time-domain and frequency-domain analyses are used, where the latter can determine acoustic dispersion if the specimen is made up of a dispersive material. Time of flight data is sensed from a series of transmitted ultrasonic waves, some of which are reflected and some of which are transmitted. The time of flight data can be used to calculate speed of sound in the tube, as well as wall thickness. Inherent in the time of flight data is the speed of the ultrasonic wave; accordingly, correction for temperature variations in the tube is not required. The calculations based on measured speed of sound quantities produces more accurate results than in calculations where the speed of sound in the specimen is assumed.
59 Citations
18 Claims
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1. A method of determining the wall thickness of a tubular workpiece and the speed of sound within said tubular workpiece from a single set of measured time of flight data, said method comprising the steps of:
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configuring an acoustic couplant medium;
defining a transmission path in said acoustic couplant medium;
selectively disposing said tubular workpiece in said acoustic couplant medium such that said tubular workpiece is in said transmission path;
defining, along said transmission path, an acoustic discontinuity at each interface between a surface of said tubular workpiece and said acoustic couplant medium;
transmitting a plurality of ultrasonic waves through said transmission path, at least one of said plurality of ultrasonic waves being transmitted without the presence of said tubular workpiece in said transmission path;
receiving signals corresponding to;
said plurality of transmitted ultrasonic waves that are reflected from at least one of said acoustic discontinuities; and
said plurality of transmitted ultrasonic waves that traverse the substantial entirety of said transmission path;
measuring time of flight data for each of said received signals;
calculating a speed of sound in said tubular workpiece based on said measured time of flight data; and
calculating a thickness of each wall of said tubular workpiece based on said measured time of flight data and said calculated speed of sound. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
and said thickness of a second of said walls is calculated using the equation where said speed of sound c is calculated using the equation where cw(T) represents a predetermined value for the speed of sound of said ultrasonic waves in said acoustic couplant medium as a function of temperature, and said measured time of flight data corresponds to Δ
t1, Δ
t2 and Δ
t3, which represent time of arrival differences associated with reflections off the inner and outer surfaces of said first wall, reflections off the inner and outer surfaces of said second wall, and time of arrival differences associated with transmission of said waves through said substantial entirety of said transmission path based on said selective presence of said workpiece in said transmission path, respectively.
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6. A method according to claim 1, wherein said received signals correspond to phase differences of at least a portion of said ultrasonic waves, said received signals configured to effect a frequency-domain analysis.
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7. A method according to claim 6, wherein said thickness of a first of said walls is calculated using the equation
- θ
1 4 π f V p ( f ) and said thickness of a second of said walls is calculated using the equation where said speed of sound is represented by a phase velocity as a function of frequency Vp(f), and is calculated using the equation where cw(T) represents a predetermined value for the speed of sound of said ultrasonic waves in said acoustic couplant medium as a function of temperature, and said measured time of flight data corresponds Δ
θ
1(f), Δ
θ
2(f) and Δ
θ
3(f), which represent phase spectra differences at each frequency associated with reflections off the inner and outer surfaces of said first wall, reflections off the inner and outer surfaces of said second wall, and phase spectra differences associated with transmission of said waves through said substantial entirety of said transmission path based on said selective presence of said workpiece in said transmission path, respectively.
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8. A method according to claim 1, wherein said tubular workpiece is disposed in said transmission path such that during the step of transmitting a plurality of ultrasonic waves, said waves impinge substantially orthogonal to the outer and inner surfaces of said tubular workpiece.
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9. A system for determining the wall thickness of an object and the speed of sound within said object from a single set of measured time of flight data, said system comprising:
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an acoustic couplant medium with a transmission path defined therein, said acoustic couplant medium configured to selectively receive a tubular workpiece disposed in said transmission path such that each interface between a surface of said tubular workpiece and said acoustic couplant medium defines an acoustic discontinuity;
a plurality of ultrasonic wave transducers cooperative with said acoustic couplant medium, said plurality of ultrasonic wave transducers configured to transmit and receive signals, said received signals corresponding to time of flight data from;
reflections of at least a portion of said ultrasonic waves from said acoustic discontinuities; and
transmitted ultrasonic waves that traverse the substantial entirety of said transmission path;
signal processing apparatus operatively coupled to said plurality of ultrasonic wave transducers, said signal processing apparatus configured to;
calculate the speed of sound within said tubular workpiece based on said received signals without having to determine the temperature of said tubular workpiece; and
calculate the thickness of each wall of said tubular workpiece based on said time of flight data and said calculated speed of sound. - View Dependent Claims (10, 11)
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12. A method of determining the wall thickness of and speed of sound within a tubular workpiece, said method comprising the steps of:
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configuring an acoustic couplant medium;
transmitting an ultrasonic wave through said acoustic couplant medium;
receiving said transmitted ultrasonic wave;
measuring a time of flight for said transmitted ultrasonic wave;
placing said tubular workpiece in said acoustic couplant medium;
generating ultrasonic waves within said acoustic couplant medium such that at least a portion of said waves are reflected back from at least one surface of said tubular workpiece, and at least a portion of said waves are transmitted through said couplant medium and said tubular workpiece;
detecting, from said waves, signals corresponding to;
a portion reflected off said at least one surface of said tubular workpiece; and
a portion transmitted through said couplant medium and said tubular workpiece;
measuring time of flight data for each of said detected signals;
calculating a speed of sound in said tubular workpiece based on said measured time of flight data; and
calculating a thickness of each wall of said tubular workpiece based on said measured time of flight data and said calculated speed of sound. - View Dependent Claims (13)
extracting the spectral content of each of said detected signals from said time of flight data; and
generating output signals for a plurality of discrete frequencies within said spectral content, said output signals proportional to the wall thickness of at least one wall of said tubular workpiece.
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14. A method of determining the wall thickness of and speed of sound within a hollow workpiece, said method comprising the steps of:
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configuring an acoustic couplant medium;
defining a transmission path in said acoustic couplant medium;
selectively disposing said hollow workpiece in said acoustic couplant medium such that said hollow workpiece is in said transmission path;
defining, along said transmission path, an acoustic discontinuity at each interface between a surface of said hollow workpiece and said acoustic couplant medium;
transmitting a plurality of ultrasonic waves through said transmission path, at least one of said plurality of ultrasonic waves being transmitted without the presence of said hollow workpiece in said transmission path;
receiving signals corresponding to;
said plurality of transmitted ultrasonic waves that are reflected from at least one acoustic discontinuity; and
said plurality of transmitted ultrasonic waves that traverse the substantial entirety of said transmission path;
measuring time of flight data for each of said received signals;
calculating a speed of sound in said hollow workpiece based on said measured time of flight data; and
calculating a thickness of each wall of said hollow workpiece based on said measured time of flight data and said calculated speed of sound. - View Dependent Claims (15)
extracting, based on said time of flight data, the spectral content of each of said received signals; and
generating output signals for a plurality of discrete frequencies within said spectral content, said output signals proportional to the thickness of said hollow workpiece.
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16. A method of determining the wall thickness of a tubular workpiece and the speed of sound within said tubular workpiece, said method comprising the steps of:
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configuring an acoustic couplant medium;
transmitting a first ultrasonic pulse through said acoustic couplant medium when said tubular workpiece is disposed therein such that at least a portion of said first ultrasonic pulse echoes off at least one surface of said tubular workpiece;
transmitting a second ultrasonic pulse through said acoustic couplant medium when said tubular workpiece is disposed therein such that at least a portion of said second ultrasonic pulse echoes off at least one surface of said tubular workpiece;
transmitting a third ultrasonic pulse through said acoustic couplant medium when said tubular workpiece is disposed therein such that at least a portion of said third ultrasonic pulse passes diametrically through the substantial entirety of both said tubular workpiece and said acoustic couplant medium;
transmitting a fourth ultrasonic pulse through said acoustic couplant medium when said tubular workpiece is not disposed therein such that at least a portion of said fourth ultrasonic pulse passes diametrically through the substantial entirety of said acoustic couplant medium;
detecting signals corresponding to said transmitted first, second, third and fourth ultrasonic pulses;
measuring time of flight data for said detected signals;
calculating a speed of sound in said tubular workpiece based on said measured time of flight data; and
calculating a thickness of each wall of said tubular workpiece based on said measured time of flight data and said calculated speed of sound. - View Dependent Claims (17)
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18. A method of determining the wall thickness of a tube and speed of sound within said tube, said method comprising the steps of:
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selectively disposing said tube in an acoustic couplant medium;
defining a transmission path in said acoustic couplant medium;
defining, along said transmission path, an acoustic discontinuity at each interface between a surface of said tube and said acoustic couplant medium;
generating a plurality of ultrasonic waves at least one of which is generated without the presence of said tube in said transmission path;
measuring the time of flight of the portion of said plurality of ultrasonic waves that reflects off the first of said acoustic discontinuities encountered along said transmission path;
measuring the time of flight of the portion of said plurality of ultrasonic waves that reflects off the second of said acoustic discontinuities encountered along said transmission path;
measuring the time of flight of the portion of said plurality of ultrasonic waves that reflects off the third of said acoustic discontinuities encountered along said transmission path;
measuring the time of flight of the portion of said plurality of ultrasonic waves that reflects off the fourth of said acoustic discontinuities encountered along said transmission path;
measuring the time of flight of the portion of said plurality of ultrasonic waves that passes through said tubular member and across the substantial entirety of said transmission path;
measuring the time of flight of the portion of said plurality of ultrasonic waves that passes across the substantial entirety of said transmission path when said tubular member is not disposed therein;
calculating a speed of sound in said tube based on said measured time of flight data; and
calculating a thickness of each wall of said tube based on said calculated speed of sound and said measured time of flight data.
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Specification