WO2006031813A2 - Systeme et procede de detection de fissures et de leur emplacement - Google Patents

Systeme et procede de detection de fissures et de leur emplacement Download PDF

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Publication number
WO2006031813A2
WO2006031813A2 PCT/US2005/032568 US2005032568W WO2006031813A2 WO 2006031813 A2 WO2006031813 A2 WO 2006031813A2 US 2005032568 W US2005032568 W US 2005032568W WO 2006031813 A2 WO2006031813 A2 WO 2006031813A2
Authority
WO
WIPO (PCT)
Prior art keywords
circuit
resonant frequency
magnetic field
region
resonant
Prior art date
Application number
PCT/US2005/032568
Other languages
English (en)
Other versions
WO2006031813A3 (fr
Inventor
Stanley E. Woodard
Qamar A. Shams
Original Assignee
United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/229,438 external-priority patent/US7255004B2/en
Application filed by United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration filed Critical United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
Publication of WO2006031813A2 publication Critical patent/WO2006031813A2/fr
Publication of WO2006031813A3 publication Critical patent/WO2006031813A3/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/24—Investigating the presence of flaws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws

Definitions

  • This invention relates to crack detection in structures. More specifically, the invention is a system and method for detecting cracks and their location in materials/structures.
  • Another object of the present invention is to provide a system and method of in-situ crack determination that does not affect the material or structure to which it is coupled.
  • Another object of the present invention is to provide a system and method for determining if material has been torn or damaged.
  • a system and method are provided for detecting cracks and their location in a structure. At least one circuit is coupled to a structure where each such circuit has a plurality of capacitive strain sensors coupled sequentially and in parallel to one another and in parallel to at least one inductor.
  • the circuit When excited by a variable magnetic field, the circuit has a resonant frequency that is (i) a first resonant frequency when the circuit is in an unstrained state, (ii) one of a plurality of second resonant frequencies when the circuit is in a strained state, (iii) a third resonant frequency when the circuit has been broken and the remaining active circuit is in an unstrained state that is substantially different in frequency from the first resonant frequency, and (iv) one of a plurality of fourth resonant frequencies when the circuit is broken and the remaining active circuit is in a strained state that are substantially different in frequency than the plurality of second frequencies when at least a portion of the circuit is strained but not broken.
  • a magnetic field response recorder wirelessly transmits the variable magnetic field to the inductor and senses the resonant frequency of the circuit so- excited by the variable magnetic field.
  • FIG. 1 is a schematic view of a system for detecting cracks in a structure in accordance with the present invention
  • FIG. 2 is an isolated, enlarged view of a capacitive strain sensor used in the present invention
  • FIG. 3 is a plan view of a structure having crack-sensing circuits coupled to a surface thereof in accordance with an embodiment of the present invention
  • FIG. 4 is a side schematic view of a multi-layer structure having crack-sensing circuits disposed between the structure's layers;
  • FIG. 5 is a schematic view of another crack- sensing circuit embodiment that includes a substrate;
  • FIG. 6 is a side schematic view of the FIG. 5 crack-sensing circuit embodiment immersed in a curing material.
  • FIG. 7 is a schematic view of a crack-sensing circuit embodiment useful for package tampering detection.
  • FIG. 1 a system for monitoring strain in a structure in order to detect cracks and their location in the structure is shown and is referenced generally by numeral 10.
  • system 10 can be placed in-situ on and/or in a wide variety of structures to include static structures, mobile vehicle structures, structures made from previously-cured homogenous or multi-layer materials, and homogenous or multi-layer structures that are in a curing phase. Accordingly, it is to be understood that any reference made herein to particular types of structures is done so for purposes of illustration and not limitation.
  • Crack detection and location system 10 uses a circuit arrangement 12 of capacitive strain sensors (“CSS") 14 electrically coupled in parallel to an inductor 18 (e.g., a spiral inductor) at one end of circuit arrangement 12 and a magnetic field response recorder 20 capable of inductive coupling to inductor 18. More specifically, circuit arrangement 12 is defined by a plurality of CSS 14 that are coupled in sequence to one another in an electrically parallel fashion by electrical leads 16. Each CSS 14 can be constructed from interdigitated electrodes 140/142 as illustrated in FIG. 2 where a separation distance "d" is defined between any two electrodes 140 and 142. The separation distance d affects the capacitance of CSS 14 so that changes in d causes capacitance changes in CSS 14.
  • CCS capacitive strain sensors
  • the separation distance d is affected by any strain that the surface, to which any CSS 14 is affixed, experiences. If circuit 12 is resonating, the resonant frequency thereof is dependent on the capacitance of CSS 14. Accordingly, changes in the capacitance of CSS 14 produce an attendant change in the resonant frequency of circuit 12.
  • Circuit arrangement 12 is coupled to a structure to be monitored such that circuit arrangement 12 has minimal structural integrity (i.e., the circuit strains/breaks in correspondence with the structure to which it is coupled) .
  • Circuit arrangement 12 could be realized through a variety of thin-film fabrication techniques to include deposition directly on an electrically non-conductive structure or on a thin-film insulating substrate that is coupled to an electrically conductive structure.
  • circuit arrangement 12 is in place on a structure, the circuit is excited to resonance by application of a variable-magnetic field (e.g., a broadband time-varying magnetic field or a single harmonic magnetic field) .
  • a variable-magnetic field e.g., a broadband time-varying magnetic field or a single harmonic magnetic field
  • circuit arrangement 12 will have a resonant frequency attributable to the capacitance of each unstrained CSS 14.
  • the strain develops in the structure beneath one of CSS 14 (hereinafter referred to as the "affected CSS 14"), the strain will impose a corresponding strain on the affected CSS 14. If the strain is sufficient, it can affect the separation distance d (FIG.
  • circuit arrangement 12 is calibrated so that a strain/break at each CSS 14 creates a unique and known corresponding resonant frequency of circuit arrangement 12.
  • a crack as well as the approximate location thereof in/on the structure.
  • the application of the variable magnetic field to circuit arrangement 12 and reading of the induced resonant frequency thereof is accomplished by inductively coupling magnetic field response recorder 20 to inductor 18.
  • the operating principles and construction details of recorder 20 are provided in U.S. Patent Application Serial No. 10/839,445, the contents of which are hereby incorporated by reference.
  • magnetic field response recorder 20 generates and wirelessly transmits a variable magnetic field that is inductively coupled to inductor 18.
  • a current is induced in circuit 12 as a result of Faraday induction.
  • a harmonic magnetic field is produced in inductor 18.
  • the magnetic field frequency in inductor 18 is that of the resonant frequency of circuit 12.
  • the resonant frequency of the entirety of circuit arrangement 12 is thus "read” by recorder 20.
  • a strain or break in a particular location or region along circuit arrangement 12 produces a unique resonant frequency. When a break occurs, the frequency is indicative of the location/region that experienced the break.
  • each of circuit arrangements 12 has a total of N CSS 14 with CSS IA 1 through CSS 14( N -i) being coupled to surface 100 and CSS 14 N remaining uncoupled from surface 100.
  • the inboard CSS 14 i.e., CSS 14 N
  • circuit arrangement 12 will always yield a resonant frequency response regardless of where the structure cracks.
  • circuit arrangement 12 can be positioned anywhere on surface 100 in any desired orientation.
  • the present invention can also be used to detect cracks in layers of a multi-layer structure. For example, as shown in FIG. 4, the connected ones of CSS 14 forming one of the above-described circuit arrangements can be positioned/interposed between layers 202 of a multi-layer structure 200. Thus, the present invention can be used to provide a three-dimensional "view" of crack detection and localization.
  • circuit arrangement 12 would typically be mounted on a substrate 30 such as a thinyfilm or mesh. Substrate 30 and circuit arrangement 12 would then be immersed in a material 300 prior to the curing thereof.
  • the present invention can be used to determine whether package tampering has occurred.
  • a repetition of inductors 18 and CSS 14 are electrically coupled in parallel, forming circuit 500, and deposited on a substrate 400 (e.g., tape with a low in- plane strength) that can be easily broken.
  • Each CSS 14 can be constructed from sets of interdigitated electrodes 140/142.
  • the circuit 500 should contain at least two inductors and three CSS 14 such that a CSS 14 is placed between the inductors and on either side of each inductor. The circuit 500 will thus result in one or more resonant circuits should the circuit 500 be broken anywhere on the circuit.
  • the substrate 400 has an adhesive on at least one side for adherence to the surface (e.g., a package) to be monitored.
  • the circuit 500 has a unique resonant frequency- indicative of no damage/tampering. The resonant frequency is measured using a magnetic field response recorder 20 once the circuit 500 and substrate 400 are affixed on or in a package.
  • the substrate 400 will be broken, thus breaking the circuit 500 resulting in one or more new resonant frequencies.
  • the new resonant frequencies are indicative of package tampering.
  • the substrate 400 is monitored using the magnetic field response recorder 20 to ascertain if the resonant frequency has changed, thus indicating whether the circuit has been broken. Such monitoring can indicate, for example, whether package tampering has occurred.
  • the advantages of the present invention are numerous. Cracks are detected and localized by a simple, in- situ system. Crack detection can be continuously or periodically monitored as needed. The system and method utilizes thin-film devices so that structure integrity and performance are not affected.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

L'invention concerne un système et un procédé de détection de fissures et de leur emplacement dans une structure. Un circuit couplé à une structure comprend des capteurs de contrainte capacitifs couplés séquentiels et parallèles les uns aux autres. Lorsqu'il est excité par un champ magnétique variable, le circuit présente une fréquence de résonance différente pour des états contraints ou pour des états non contraints. Pour les états contraints, la fréquence de résonance indique une zone du circuit qui subit une contrainte induite par une contrainte dans une zone de la structure se trouvant à proximité de cette zone du circuit. Une bobine d'induction est couplée électriquement à une extrémité de chaque circuit. Un enregistreur de réaction à un champ magnétique transmet sans fil le champ magnétique variable à la bobine d'induction, et détecte la fréquence de résonance du circuit ainsi excité par le champ magnétique variable.
PCT/US2005/032568 2004-09-13 2005-09-13 Systeme et procede de detection de fissures et de leur emplacement WO2006031813A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US61117004P 2004-09-13 2004-09-13
US60/611,170 2004-09-13
US11/229,438 2005-09-12
US11/229,438 US7255004B2 (en) 2004-09-13 2005-09-12 Wireless fluid level measuring system

Publications (2)

Publication Number Publication Date
WO2006031813A2 true WO2006031813A2 (fr) 2006-03-23
WO2006031813A3 WO2006031813A3 (fr) 2007-04-26

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PCT/US2005/032568 WO2006031813A2 (fr) 2004-09-13 2005-09-13 Systeme et procede de detection de fissures et de leur emplacement

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105960648A (zh) * 2014-02-03 2016-09-21 寇特·路达尔 道路、车道及铁道障碍的早期警示系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3918299A (en) * 1973-03-23 1975-11-11 Siderurgie Fse Inst Rech Arrangement for use in the study of the propagation of cracks
US4579004A (en) * 1983-09-24 1986-04-01 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Instrument for detecting the instant at which a crack begins in a mechanical strength test of a ferromagnetic metal
US7082833B2 (en) * 2003-06-06 2006-08-01 Luna Innovations Method and apparatus for determining and assessing a characteristic of a material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3918299A (en) * 1973-03-23 1975-11-11 Siderurgie Fse Inst Rech Arrangement for use in the study of the propagation of cracks
US4579004A (en) * 1983-09-24 1986-04-01 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Instrument for detecting the instant at which a crack begins in a mechanical strength test of a ferromagnetic metal
US7082833B2 (en) * 2003-06-06 2006-08-01 Luna Innovations Method and apparatus for determining and assessing a characteristic of a material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105960648A (zh) * 2014-02-03 2016-09-21 寇特·路达尔 道路、车道及铁道障碍的早期警示系统

Also Published As

Publication number Publication date
WO2006031813A3 (fr) 2007-04-26

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