DISTRIBUTED CIRCLE METHOD FOR GUIDED WAVE BASED CORROSION DETECTION IN PLATE-LIKE STRUCTURES
First Claim
1. A method for characterizing a thickness deviation in at least a portion of a plate-like structure, the method comprising:
- deploying adjacent to at least a portion of a plate-like structure a sensor network comprising a plurality of transducers, the at least a portion of the plate-like structure having a presumed substantially uniform pristine thickness and formed of an presumed substantially homogenous material and characterized by a known dispersion curvatures that depend on the plate thickness and material properties;
propagating guided waves through the at least a portion of the plate-like structure within the sensor network, wherein the sensor network provides at least four discrete wave transmission paths that traverse the at least a portion of the plate-like structure;
determining the velocity of the guided waves along each discrete wave transmission path based on a predetermined distance between sensors that define the path and the time of flight of the transmitted waves along the wave transmission path;
detecting within the at least a portion of the plate-like structure the presence of any deviation in thickness from the presumed pristine thickness, wherein a deviation in thickness is present when the determined velocity along at least one of the wave transmission paths deviates from an expected pristine guided wave velocity provided by the known wave mode velocities that depend on the relationship between wavelength and plate thickness; and
estimating the location and approximate area of any deviation in the thickness within the at least a portion of the plate-like structure, wherein a deviation in thickness is present when at least four wave transmission paths traverse the deviation as evidenced by a detected deviation of velocity from expected pristine guided wave velocities along at least four wave transmission paths, and whereby the location and size of a patch of thickness deviation is estimated as a circle based on the determined velocities and predetermined distances for each of the transmission paths, and the expected pristine guided wave velocity provided by the known wave mode velocities that depend on the relationship between wavelength and plate thickness.
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Abstract
A system and methods for defect detection and characterization in plate-like structures, more particularly to detect corrosion in complex plate-like structures that result in a deviation in thickness in at least a patch of the structure. The system comprises a plurality of transducers configured to be adjacent to at least a portion of a plate-like structure. A controller is coupled to the plurality of transducers. The method includes propagation of guided waves through the plate-like structure and capture of data to detect the presence of at least one defect using at least a pair of transmitting/receiving transducers based on a change in the velocity of wave transmission as compared to the velocity predicted for a pristine structure. The method also includes estimated localization, and estimation in size and change in thickness of one or more patches using at least four discrete wave transmission paths that traverse the defect by using optimization of a proposed error function to estimate based on distributed circles using a derivative free optimization based algorithm.
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Citations
21 Claims
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1. A method for characterizing a thickness deviation in at least a portion of a plate-like structure, the method comprising:
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deploying adjacent to at least a portion of a plate-like structure a sensor network comprising a plurality of transducers, the at least a portion of the plate-like structure having a presumed substantially uniform pristine thickness and formed of an presumed substantially homogenous material and characterized by a known dispersion curvatures that depend on the plate thickness and material properties; propagating guided waves through the at least a portion of the plate-like structure within the sensor network, wherein the sensor network provides at least four discrete wave transmission paths that traverse the at least a portion of the plate-like structure; determining the velocity of the guided waves along each discrete wave transmission path based on a predetermined distance between sensors that define the path and the time of flight of the transmitted waves along the wave transmission path; detecting within the at least a portion of the plate-like structure the presence of any deviation in thickness from the presumed pristine thickness, wherein a deviation in thickness is present when the determined velocity along at least one of the wave transmission paths deviates from an expected pristine guided wave velocity provided by the known wave mode velocities that depend on the relationship between wavelength and plate thickness; and estimating the location and approximate area of any deviation in the thickness within the at least a portion of the plate-like structure, wherein a deviation in thickness is present when at least four wave transmission paths traverse the deviation as evidenced by a detected deviation of velocity from expected pristine guided wave velocities along at least four wave transmission paths, and whereby the location and size of a patch of thickness deviation is estimated as a circle based on the determined velocities and predetermined distances for each of the transmission paths, and the expected pristine guided wave velocity provided by the known wave mode velocities that depend on the relationship between wavelength and plate thickness. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for identifying corrosion in at least a portion of a plate-like structure, comprising:
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arranging a plurality of transducers along a boundary of a corrosion detection area of the planar structure, the transducers paired to transmit and receive between them along a rectilinear communication path along the planar structure; actuating the transducers to propagate guided waves between each of the transducer pairs; capturing and processing the data obtained from the transmissions between the transducer pairs; analyzing the resultant data, and wherein, discrete diminution in wall thickness is detected and corrosion patch size is estimated when the boundary of a corrosion patch falls within an area of the plate-like structure that is traversed by at least four transducer pair communication paths. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A sensor network for corrosion detection in a plate-like structure, comprising:
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a plurality of at least four pairs of transducers arranged along a boundary of a detection area of at least a portion of a plate-like structure, each transducer configured as one of; a transmitter that transmits guided ultrasound wave signals; a receiver that receives guided ultrasound wave signals; and a transmitter and a receiver (a dual mode transducer) the plurality of transducers configured to enable communication of guided ultrasound waves through the wall of the plate-like structure along a rectilinear path between paired transmitter and receiver transducers; the boundary defining a detection area that is at least the size of a preselected minimum detection area, such that at least four independent transducer pair paths cross the preselected minimum detection area; and a transducer controller system for actuating the transducers, capturing and processing data obtained from the transmissions between paired transducers, and analyzing the data to do one or more of; detect and provide an estimated location of each of one or more corrosion patches within the detection area of the plate-like structure; provide an estimated size of each of the one or more detected corrosion patches; and provide an estimated reduction in thickness of the wall of the plate-like structure within each of the one or more detected corrosion patches, such estimating provided using optimization of a proposed error function. - View Dependent Claims (15, 16, 17, 18, 19)
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- 20. The sensor network according to claim 20, wherein arrangement of each transducer relative to the others is adjustable to enable variable adjustment of the boundary of the detection area.
Specification