WO2018093855A1 - Vérification de l'intégrité structurale de matériaux par stimulation par champ magnétique - Google Patents

Vérification de l'intégrité structurale de matériaux par stimulation par champ magnétique Download PDF

Info

Publication number
WO2018093855A1
WO2018093855A1 PCT/US2017/061737 US2017061737W WO2018093855A1 WO 2018093855 A1 WO2018093855 A1 WO 2018093855A1 US 2017061737 W US2017061737 W US 2017061737W WO 2018093855 A1 WO2018093855 A1 WO 2018093855A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrical
crack
inductor
electrical loss
defect
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/US2017/061737
Other languages
English (en)
Inventor
David H. Redinger
Christopher R. Yungers
Ronald D. Jesme
Jennifer F. Schumacher
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
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
Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of WO2018093855A1 publication Critical patent/WO2018093855A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/20—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
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
    • 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
    • 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
    • G01N27/83—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields
    • G01N27/87—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields using probes

Definitions

  • the disclosure relates to techniques for verifying structural integrity of materials.
  • Ceramic body plating is used to protect soldiers, police officers, and other security personnel from projectiles. Ceramic body plating may be useful when undamaged, but may be replaced after being damaged, e.g., after cracking.
  • X-ray scanning including X-ray radiography and X-ray computed tomography (CT scanning) may be used to detect cracks or other defects in materials.
  • CT scanning X-ray computed tomography
  • X-ray scanning and X-ray CT scanning may be relatively expensive, relatively slow, or both.
  • this disclosure describes systems and techniques for verifying structural integrity of a material using magnetic field stimulation.
  • Cracks in a material may affect conductivity (and resistivity) of the material, which in turn may affect parameters of the material induced using magnetic field stimulation, including electrical loss and formation of induced currents in the material.
  • a magnetic field stimulation-based measurement may be used to determine if the material includes a crack or other defect.
  • the parameter measured using magnetic field stimulation may include electrical loss of the inductor, induced voltages, induced currents, or the like.
  • the parameter measurement induced using magnetic field stimulation may be used to determine whether the material is damaged or intact.
  • the disclosure describes a method for detecting a crack or defect in a material.
  • the method may include applying an electrical signal to an inductor adjacent to the material; determining an electrical loss in the inductor due to the material; and determining whether the material includes a crack or other defect based on the electrical loss.
  • the disclosure describes a system including a material; an inductor adjacent to the material; an electrical signal source configured to apply an electrical signal to the at least one inductor; and a computing device.
  • the computing device may be configured to determine an electrical loss in the inductor due to the material and determine whether the material includes a crack or other defect based on the electrical loss.
  • the disclosure describes a system including an electrical signal source; an inductor electrically coupled to the electrical signal source; a pair of electrical contacts; and a computing device.
  • the computing device may be configured to cause the electrical signal source to apply an electrical signal to the inductor when a material is adjacent to the inductor.
  • the computing device also may be configured to determine an induced voltage or current across the pair of electrical contacts, wherein the electrical contacts are electrically coupled to a pair of electrodes electrically coupled to the material. Further, the computing device may be configured to determine whether the material includes a crack or other defect based on the induced voltage or current.
  • the disclosure describes a method for detecting a crack or defect in a material.
  • the method may include applying an electrical signal to an inductor adjacent to a material; determining an induced voltage or current across a pair of electrical contacts electrically coupled to the material; and determining whether the material includes a crack or other defect based on the induced voltage or current.
  • a crack detection system utilizing magnetic field stimulation may offer at least one of improved portability, speed, or cost compared to an X-ray radiography or X-ray computed tomography system, while offering sufficient accuracy and detail to enable detection of cracks or other defects in a material being used in the field.
  • a crack detection system utilizing magnetic field stimulation may allow relatively computationally cheap analysis techniques to be used to analyze the parameter measurements and determine whether the material includes a crack or other defect.
  • FIG. 1 is a conceptual and schematic diagram block illustrating an example system for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • FIG. 2 is a conceptual and schematic diagram block illustrating another example system for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • FIG. 3 is a conceptual and schematic diagram block illustrating another example system for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • FIG. 4 is flow diagram illustrating an example technique for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • FIG. 5 is a conceptual and schematic diagram block illustrating another example system for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • FIG. 6 is a conceptual and schematic diagram block illustrating another example system for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • FIG. 7 is flow diagram illustrating another example technique for determining whether a material includes a crack or other defect using magnetic field stimulation.
  • the disclosure describes systems and techniques for verifying structural integrity of a material.
  • the techniques may utilize magnetic field stimulation to induce voltage or current in a material and determine a related parameter to determine whether the material includes a crack or other defect.
  • an electrical signal source may apply an electrical signal to an inductor adjacent to the material and a computing device may determine the resulting magnetic field stimulation-related parameter.
  • the magnetic field stimulation-related parameter may include, for example, electrical loss in the inductor due to the material, induced voltage in the material, induced current in the material, or the like.
  • a reduction in the electrical loss in the inductor compared to a control electrical loss or a reduction in induced voltage or current in the material compared to a control voltage or current may indicate that the material includes a crack or other defect.
  • the control electrical loss and the control induced voltage or current may be determined using one or more techniques. For example, the electrical loss and the control induced voltage or current may be determined for the material when the material is known to be intact (undamaged), the control electrical loss and the control induced voltage or current may be determined using a model of the material in an intact
  • the control electrical loss and the control induced voltage or current may be determined as an average (e.g., mean) of a plurality of similar materials (e.g., in geometry and composition) that are known to be intact (undamaged).
  • the determined magnetic field stimulation-related parameter instead of comparing the determined magnetic field stimulation-related parameter to a control magnetic field stimulation-related parameter, the determined magnetic field stimulation-related parameter may be compared to a predetermined threshold magnetic field stimulation-related parameter.
  • the predetermined threshold magnetic field stimulation-related parameter may be selected so that a determined magnetic field stimulation-related parameter below the threshold magnetic field stimulation- related parameter value is indicative of a crack or other defect and a determined magnetic field stimulation-related parameter above the threshold magnetic field stimulation-related parameter value is not indicative of a crack or other defect.
  • a magnetic field stimulation-related parameter measurement for verifying structural integrity may provide advantages compared to other techniques for verifying structural integrity.
  • Using resistivity measurement using a current directly applied to the material may be affected not only by electrical property variations in the material under test, but also in any electrical connections between the measurement apparatus and the material, such as within electrical leads, in electrical contact between the leads and the material, or the like.
  • variations in electrical properties of these components may complicate measurement of resistivity of the material under test, as these electrical properties may vary differently (in magnitude, direction, or both) than the electrical properties of the material under test.
  • one or more of these electrical properties may actually vary to a greater extent than the change in resistivity in the material due to a crack, which may obscure the change in resistivity in the material due to a crack.
  • a magnetic field stimulation-related parameter measurement may facilitate detection of cracks or other defects in a material.
  • X-ray radiography or X-ray computed tomography may be used to detect cracks in a material.
  • CT computed tomography
  • X-ray radiography and X-ray CT utilize relatively large, relatively expensive equipment to perform the crack detection. This may prevent X-ray radiography and X-ray CT from being portable, such as being used to test materials in the environments in which they are used.
  • X-ray radiography and X-ray CT may be relatively time consuming and computationally expensive.
  • a magnetic field stimulation-related parameter measurement utilizes relatively smaller, relatively less expensive equipment.
  • the equipment may enable portable crack detection systems, which may be used to detect cracks in materials in situ rather than requiring removing the materials to be tested to the testing equipment.
  • a magnetic field stimulation-related parameter measurement crack detection system may allow relatively
  • FIG. 1 is conceptual and schematic diagram block illustrating an example system 10 for determining presence of a crack or other defect in a material 16 using a magnetic field stimulation-related parameter measurement.
  • System 10 of FIG. 1 includes a computing device 12, an electrical signal source 14, and an inductor 18.
  • Inductor 18 is adjacent to material 16, which is being tested using the inductor- related parameter measurement.
  • Material 16 may be any material for which detection of a potential crack or other defect is desired.
  • material 16 may be an electrically conductive material, an electrically semiconductive material, or a magnetically permeable material.
  • material 16 may include a metal, an alloy, a metalloid, a semiconductor, an electrically conductive or semiconductive ceramic, or the like.
  • material 16 may include a ceramic such as boron carbide (B4C), silicon carbide (SiC), alumina (AI2O3), composites thereof, or the like.
  • Material 16 may be used in any one of a wide variety of applications.
  • material 16 may be a ceramic that has relatively high hardness, a relatively high Young's modulus, a relatively high tensile strength, and may be used in ceramic armor plating.
  • Ceramic armor plating may be used in body armor for military and police personnel, vehicle armor, or the like.
  • Example materials for ceramic armor plating include boron carbide (B 4 C), silicon carbide (SiC), alumina (AI 2 O3), composites thereof, or the like.
  • Material 16 may define any geometry, and the geometry of material 16 may be based at least in part on the use for material 16.
  • ceramic armor plating may have a geometry defined by the surface that the armor plating will be applied to.
  • Example geometries for material 16 include, but are not limited to, polygonal solids, such as rectangular solids or solids with more sides.
  • Electrical signal source 14 may include any device configured to output an electrical signal to inductor 18.
  • the electrical signal may include a current signal or a voltage signal.
  • the electrical signal may include an alternating current (AC) voltage or an AC current.
  • electrical signal source 14 may include a power source, such as a battery, a capacitor, a supercapacitor, a transformer electrically connected to a mains voltage, or the like.
  • electrical signal source 14 may include analog or digital circuitry configured to receive an electrical signal from the power source and modify the electrical signal into a format suitable for output to inductor 18, e.g., to a selected electrical signal, including frequency, amplitude, phase, and the like.
  • Inductor 18 may include an electrical conductor arranged in any geometry suitable for an inductor.
  • inductor 18 may include a substantially planar coil, as shown in FIG. 1.
  • inductor 18 may include any number of windings.
  • Inductor 18 may include any suitable electrically conductive material, including, for example, copper, aluminum, silver, gold, or the like. Inductor 18 may be any size, and in some examples, may be shaped and sized to that a perimeter of inductor 18 is approximately the same size and shape as a perimeter of the surface of material 16 near which inductor 18 will be positioned. This may allow relatively complete coverage of material 16 when testing for a crack or other defect.
  • Inductor 18 may be mechanically attached to material 16.
  • inductor 18 may be mechanically attached to material 16 using an adhesive.
  • inductor 18 may be mechanically attached directly to material 16 with no intervening materials (except any adhesive used to mechanically attach inductor 18 to material 16).
  • one or more layers of material may be between inductor 18 and material 16.
  • the object of which material 16 is a part may include one or more layers of other materials on a surface of material 16, and inductor 18 may be indirectly mechanically attached to material 16, i.e., may be mechanically attached to a layer of material that is attached to material 16.
  • Inductor 18 may be attached to any surface of material 16.
  • the surface to which inductor 18 is attached may affect the direction in which induced electrical current (also referred to as eddy current) flows within material 16. Cracks or other defects may affect the magnitude of the induced electrical current more significantly when the induced electrical current flows across a plane of the crack (e.g., normal to a surface of the crack).
  • the likely locations of cracks or other defects and the likely orientation of cracks or other defects may be predicted based on the use for material.
  • inductor 18 may then be attached to material 16 so that the induced current within material 16 from current conducted through inductor 18 flows substantially normal to a predicted orientation of the crack or other defect.
  • an inductor 18 may be attached to more than one surface of material 16.
  • a respective inductor 18 may be attached to three orthogonal surfaces of the cube. By attaching a respective inductor 18 to three orthogonal surfaces, current may be induced to flow in one of three orthogonal directions depending on the inductor 18 through which current is driven. This may increase a likelihood that induced current will flow within material 16 normal to the plane of any crack in material 16. Other examples are possible for other shapes.
  • Computing device 12 is configured to control operation of system 10, including electrical signal source 14.
  • Computing device 12 may include any of a wide range of devices, including computer servers, desktop computers, notebook (i.e., laptop) computers, tablet computers, embedded computers, and the like.
  • computing device 12 may include a processor.
  • the processor may include one or more microprocessors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other digital logic circuitry.
  • DSP digital signal processors
  • ASIC application specific integrated circuits
  • FPGA field programmable gate arrays
  • computing device 12 may include an analog -to-digital converter (ADC), or system 10 may include an ADC separate from computing device 12. In examples in which the ADC is separate from computing device 12, the ADC may be electrically coupled between inductor 18 and computing device 12.
  • ADC analog -to-digital converter
  • Computing device 12 is electrically coupled to the pair of inductor 18 and communicatively coupled to electrical signal source 14.
  • Computing device 12 may be configured to cause electrical signal source 14 to apply an electrical signal to inductor 18.
  • Computing device 12 also may be configured to determine a magnetic field stimulation-related parameter in response to the electrical signal. For example, computing device 12 may be configured to determine electrical loss in inductor 18 due to material 16 being adjacent to inductor 18.
  • Computing device 12 may be configured to determine the electrical loss in inductor 18 due to material 16 in any manner. For example, computing device 12 using a resonant circuit including inductor 18 in series with a capacitor and electrical signal source 14. One terminal of electrical signal source 14 may be coupled to ground and one terminal coupled to the inductor. Similarly, one terminal of the capacitor may be attached to ground and one terminal attached to inductor 18. Computing device 12 may measure an input voltage amplitude output by electrical signal source 14 and an output voltage amplitude across the capacitor. Computing device 12 then may estimate the electrical losses in inductor 18 due to material 16 according to the following equation (1), shown in Han et al, "Evaluation of Magnetic Materials for Very High Frequency Power Applications," IEEE Power Elecgtronics Specialists
  • R CO re is the core loss due to material 16
  • V in is the input voltage amplitude output by electrical signal source 14
  • V out is the output voltage amplitude across the capacitor
  • R c is the resistance across the capacitor
  • co s is the angular frequency of the input voltage
  • C is the capacitance of the capacitor
  • Ra is the resistance across inductor 18.
  • Equations (1), (2), and (3) and the resonant circuit are one example for determining electrical loss through inductor 18 due to material 16. Other techniques also may be used to determine electrical loss through inductor 18 due to material 16.
  • Computing device 12 may be configured to determine whether material 16 includes a crack or other defect based on the determined electrical loss (e.g., either R cor e in equation (2) or Rmductor in equation (3)). For example, computing device 12 may be configured to compare the determined electrical loss to a control electrical loss. In some examples, computing device 12 or another similar device may have determined the control electrical loss at a first time. The first time may be a time at which material 16 is known to be intact, undamaged, or to not include a crack.
  • the first time may be a time at which material 16 is known to be intact, undamaged, or to not include a crack.
  • the first time may be a time at which material 16 is manufactured, or a time at which an independent measurement (e.g., X-ray radiology or X-ray CT scan) may be used to verify that material 16 is intact, undamaged, or does not include a crack.
  • computing device 12 or another device may determine the control electrical loss using a model of the material in an intact (undamaged) state, or may determine the control electrical loss as an average (e.g., mean) of a plurality of similar materials (e.g., in geometry and composition) that are known to be intact (undamaged). This control electrical loss may be stored (e.g., in a memory device associated with computing device 12) for later use.
  • system 10 then may be used to determine an electrical loss of inductor 18 due to material 16 at the later time.
  • computing device 12 may control electrical signal source 14 to apply an electrical signal to inductor 18 and determine the electrical loss, for example, using the voltage measurements and equation (2) or (3) described above.
  • Computing device 12 may then determine whether material 16 includes a crack or other defect based on the determined electrical loss, for example, by comparing determined electrical loss to the control electrical loss.
  • computing device 12 may determine a difference between a magnitude of the determined electrical loss and a magnitude of the control electrical loss.
  • the electrical loss may be less than when material 16 is intact or undamaged, as eddy currents may not flow as easily through material 16 when material 16 includes a crack or other defect.
  • Computing device 12 may compare the difference between the determined electrical loss and the control electrical loss to a threshold difference value, and may determine that material 16 includes a crack or other defect in response to the difference being greater than the threshold difference value.
  • the threshold difference value may be selected to be a meaningful difference value dividing materials that include cracks or other defects from materials that are intact (do not include cracks or other defects).
  • computing device 12 may compare the determined electrical loss to a control electrical loss to a
  • the predetermined threshold electrical loss may be selected so that a determined electrical loss below the threshold electrical loss value is indicative of a crack or other defect and a determined electrical loss above the threshold electrical loss value is not indicative of a crack or other defect.
  • an electrical loss measurement crack detection system may allow relatively computationally cheap analysis techniques to be used to analyze the electrical loss measurements and determine whether the material includes a crack or other defect.
  • a single inductor may not provide sufficient coverage for detecting cracks having at all locations and with all orientations within material 16.
  • system 10 may include a respective inductor 18 attached to each of two or more surfaces of material 16, which may improve detection of cracks having different orientations within material 16.
  • a system may include at least two inductors attached to a single surface of material 16.
  • FIG. 2 is a conceptual and schematic diagram block illustrating another example system 20 for determining whether a material 16 includes a crack or other defect using an electrical loss measurement.
  • system 20 in FIG. 2 includes computing device 12, electrical signal source 34, and material 16.
  • Each of computing device 12, electrical signal source 34, and material 16 may be similar to or substantially the same as computing device 12, electrical signal source 14, and material 16 described with reference to FIG. 1, aside from electrical signal source 14 in FIG. 2 including four terminals instead of the two terminals illustrated in FIG. 1.
  • electrical signal source 14 may include any number of terminals, or may include two terminals that are electrically coupled to inputs of a switch network whose outputs are coupled to leads of respective inductors.
  • system 20 in FIG. 2 includes a plurality of inductors.
  • system 20 includes a first inductor 28A and a second inductor 28B (collectively, "inductors 28").
  • system 20 may include any number of inductors 28, e.g., at least two inductors 28.
  • each of first inductor 28A and second inductor 28B are positioned adjacent to the same surface of material 16.
  • Each of inductors 28 may include any suitable inductor geometry, as described above with respect to inductor 18 of FIG. 1.
  • each of inductors 28 may have a similar construction (e.g., geometry, material composition, or the like), or at least one of inductors 28 may have a different construction than at least one other of inductors 28.
  • Each of inductors 28 may be mechanically attached directly to material 16 or to a layer on material 16.
  • first inductor 28A partially overlaps second inductor 28B.
  • a portion of the coil of first inductor 28A overlaps the coil of second inductor 28B.
  • the sensitivity of system 20 to crack lying in a region near the end of the coils (where the coils overlap) may be increased compared to examples in which first inductor 28A does not overlap second inductor 28B.
  • the portions of inductors 28 in which the coil is substantially vertical in FIG. 2 may have be less sensitive to cracks as the eddy currents may be less likely to flow normal to a plane of a crack.
  • first inductor 28A partially overlaps second inductor 28B the portions of inductors 28 in which the coil is substantially vertical in FIG. 2 are overlapped by a horizontal portion of the other inductor.
  • inductors 28 may be attached to multiple surfaces of material 16, e.g., orthogonal surfaces or surfaces for which normal vectors extending from the surfaces intersect. This may provide improved sensitivity for cracks at arbitrary orientations within material 16.
  • Computing device 12 may be configured to determine whether material 16 includes a crack or other defect based on the respective determined electrical loss (e.g., either R cor e in equation (2) or Rmductor in equation (3)) for each respective inductor of inductors 28. For example, computing device 12 may be configured to compare the respective determined electrical loss to a respective control electrical loss. In some examples, computing device 12 or another similar device may have determined the respective control electrical loss for each inductor of inductors 28 at a first time. The first time may be a time at which material 16 is known to be intact, undamaged, or to not include a crack.
  • the first time may be a time at which material 16 is known to be intact, undamaged, or to not include a crack.
  • the first time may be a time at which material 16 is manufactured, or a time at which an independent measurement (e.g., X-ray radiology or X-ray CT scan) may be used to verify that material 16 is intact, undamaged, or does not include a crack.
  • computing device 12 or another device may determine the control electrical loss using a model of the material in an intact (undamaged) state, or may determine the control electrical loss as an average (e.g., mean) of a plurality of similar materials (e.g., in geometry and composition) that are known to be intact (undamaged). These respective control electrical losses may be stored (e.g., in a memory device associated with computing device 12) for later use.
  • system 20 then may be used to determine a respective electrical loss associated with each of inductors 28 due to material 16 at the later time.
  • computing device 12 may control electrical signal source 14 to apply a respective electrical signal to each inductor of inductors 28 and determine the respective electrical loss, for example, using the voltage measurements and equation (2) or (3) described above.
  • Computing device 12 may then determine whether material 16 includes a crack or other defect based on the respective determined electrical losses, for example, by comparing the respective determined electrical loss to the respective control electrical loss.
  • computing device 12 may determine a difference between a magnitude of the respective determined electrical loss and a magnitude of the respective control electrical loss associated with the same inductor of inductors 28. If material 16 includes a crack or other defect in a volume in which eddy currents are induced, the respective electrical loss may be less than when material 16 is intact or undamaged, as eddy currents may not flow as easily through the volume of material 16 when material 16 includes a crack or other defect. Computing device 12 then may compare the respective differences between the respective determined electrical loss and the respective control electrical loss to a threshold difference value, and may determine that material 16 includes a crack or other defect in response to at least one of the differences being greater than the threshold difference value.
  • computing device 12 may determine that a volume of material 16 adjacent to the inductor for which the respective determined electrical loss is less than the respective control electrical loss by more than the threshold value includes a crack or other defect.
  • the threshold difference value may be selected to be a meaningful difference value dividing materials that include cracks or other defects from materials that are intact (do not include cracks or other defects).
  • computing device 12 may determine that material 16 includes a crack or other defect in response to at least a threshold number of the differences being greater than the threshold difference value .
  • computing device 12 may compare the determined electrical loss to a control electrical loss
  • the predetermined threshold electrical loss may be selected so that a determined electrical loss below the threshold electrical loss value is indicative of a crack or other defect and a determined electrical loss above the threshold electrical loss value is not indicative of a crack or other defect.
  • FIG. 3 is a conceptual and schematic diagram block illustrating another example system 30 for determining whether a material 16 includes a crack or other defect using an electrical loss measurement.
  • system 30 in FIG. 3 includes computing device 12, electrical signal source 14, and material 16.
  • Each of computing device 12, electrical signal source 14, and material 16 may be similar to or substantially the same as computing device 12, electrical signal source 14, and material 16 described with reference to FIG. 1.
  • electrical signal source 14 may include any number of terminals, or may include two terminals that are electrically coupled to inputs of a switch network whose outputs are coupled to leads of respective inductors.
  • system 30 includes a first inductor 38A and a second inductor 38B (collectively, “inductors 38") electrically coupled in series. This may reduce the number of electrical couplings between electrical signal source 14 and inductors 38 compared to examples in which each inductor of inductors 38 are electrically coupled to electrical signal source in parallel.
  • system 30 may include any number of inductors 38 electrically coupled in series, e.g., at least two inductors 38.
  • each of first inductor 38A and second inductor 38B are positioned adjacent to the same surface of material 16.
  • Each of inductors 38 may include any suitable inductor geometry, as described above with respect to inductor 18 of FIG. 1.
  • each of inductors 38 may have a similar construction (e.g., geometry, material composition, or the like), or at least one of inductors 38 may have a different construction than at least one other of inductors 38.
  • Each of inductors 38 may be mechanically attached directly to material 16 or to a layer on material 16.
  • inductors 38 may be attached to multiple surfaces of material 16, e.g., orthogonal surfaces or surfaces for which normal vectors extending from the surfaces intersect. This may provide improved sensitivity for cracks at arbitrary orientations within material 16.
  • inductors 38 on a single surface of material 16 are electrically coupled to electrical signal source 14 in series, and inductors on one surface of material 16 are electrically coupled to electrical signal source 14 in parallel with inductors on another surface of material 16.
  • inductors 38 on multiple surfaces of material 16 are electrically coupled to electrical signal source 14 in series.
  • first inductor 38A does not overlap second inductor 38B. However, in other examples, first inductor 38A may partially overlap second inductor 38B, e.g., as shown with inductors 28 of FIG. 2.
  • Computing device 12 may be configured to determine whether material 16 includes a crack or other defect based on the determined electrical loss (e.g., either R core in equation (2) or Redactor in equation (3)) for inductors 38. As inductors 38 are coupled in series, inductors 38 may not be individually addressable. For example, computing device 12 may be configured to compare the determined electrical loss to a control electrical loss. In some examples, computing device 12 or another similar device may have determined the respective control electrical loss for inductors 38 at a first time. The first time may be a time at which material 16 is known to be intact, undamaged, or to not include a crack.
  • the first time may be a time at which material 16 is known to be intact, undamaged, or to not include a crack.
  • computing device 12 or another device may determine the control electrical loss using a model of the material in an intact (undamaged) state, or may determine the control electrical loss as an average (e.g., mean) of a plurality of similar materials (e.g., in geometry and composition) that are known to be intact (undamaged). This control electrical loss may be stored (e.g., in a memory device associated with computing device 12) for later use.
  • system 30 then may be used to determine an electrical loss associated with inductors 38 due to material 16 at the later time.
  • computing device 12 may control electrical signal source 14 to apply an electrical signal to inductors 38 and determine the respective electrical loss, for example, using the voltage measurements and equation (2) or (3) described above.
  • Computing device 12 may then determine whether material 16 includes a crack or other defect based on the determined electrical loss, for example, by comparing the determined electrical loss to the control electrical loss. Computing device 12 then may compare the difference between the determined electrical loss and the control electrical loss to a threshold difference value, and may determine that material 16 includes a crack or other defect in response to the difference being greater than the threshold difference value.
  • computing device 12 may compare the determined electrical loss to a predetermined threshold electrical loss.
  • the predetermined threshold electrical loss may be selected so that a determined electrical loss below the threshold electrical loss value is indicative of a crack or other defect and a determined electrical loss above the threshold electrical loss value is not indicative of a crack or other defect.
  • FIG. 4 is flow diagram illustrating an example technique for determining presence of a crack or other defect in a material using a magnetic field stimulation-related parameter measurement.
  • the technique of FIG. 4 will be described with reference to system 10 and computing device 12 of FIG. 1 for clarity. However, it will be appreciated that the technique of FIG. 4 may be performed by other systems and computing devices (such as system 20 of FIG. 2 or system 30 of FIG. 3), and that system 10 and computing device 12 may be used to perform other techniques.
  • the technique of FIG. 4 includes applying an electrical signal to an inductor 18 adjacent to (e.g., mechanically attached to) material 16 (42).
  • computing device 12 may be configured to cause electrical signal source 14 to generate an electrical signal with a predetermined voltage or current.
  • the predetermined voltage or current may include an AC voltage or current.
  • Computing device 12 also may control electrical signal source 14 to generate the electrical signal with a selected amplitude, duration, phase, frequency, and other signal characteristics.
  • the technique of FIG. 4 also includes, while applying the electrical signal to inductor 18, determining an electrical loss in inductor 18 due to material 16 (44).
  • computing device 12 may be configured determine the electrical loss in inductor 18 using the voltages and equation (2) or (3) described with reference to FIG. 1.
  • the technique of FIG. 2 further includes determining whether material 16 includes a crack or other defect based on the electrical loss (46).
  • computing device 12 may be configured to determine whether material 16 includes a crack or other defect by comparing the determined electrical loss to a control electrical loss determined for material 16 when material 16 is known to be intact or undamaged.
  • Computing device 12 may compare the difference between the determined electrical loss and the control electrical loss to a threshold difference value, and may determine that material 16 includes a crack or other defect if the difference between the determined electrical loss and the control electrical loss is greater than the threshold difference value.
  • computing device 12 may determine that material 16 includes a crack or other defect if the determined electrical loss is less than the control electrical loss by more than the threshold difference value.
  • computing device 12 may compare the determined electrical loss to a control electrical loss
  • the predetermined threshold electrical loss may be selected so that a determined electrical loss below the threshold electrical loss value is indicative of a crack or other defect and a determined electrical loss above the threshold electrical loss value is not indicative of a crack or other defect.
  • a system may determine whether a material includes a crack or other defect based on another magnetic field stimulation-related parameter, such as an induced current or voltage.
  • another magnetic field stimulation-related parameter such as an induced current or voltage.
  • the inductor may be physically separate from the material, and the material may include at least one electrode at which an induced voltage or current is measured.
  • FIG. 5 is a conceptual and schematic diagram block illustrating another example system 50 for determining whether a material 16 includes a crack or other defect using a magnetic field stimulation-related parameter measurement, in this case, an induced voltage or current.
  • System 50 includes computing device 52, electrical signal source 14, switch network 54, enclosure 56, and inductor 60.
  • Electrical signal source 14 may be similar to or substantially the same as electrical signal source 14 of FIGS. 1-3.
  • Material 16 may be similar to or substantially the same as material 16 described with reference to
  • FIGS. 1-3 In the example of FIG. 5, plurality of electrodes 62 are attached to material 16.
  • computing device 52 in FIG. 5 may be configured to control switch network 54 to selectively couple a pair of electrodes from plurality of electrodes 62 to computing device 52 to allow computing device 52 to measure a voltage across the pair of electrodes.
  • Plurality of electrodes 62 are electrically coupled to material 16, which is being tested using an inductor -related parameter measurement.
  • Each electrode of plurality of electrodes 68 is electrically coupled to material 16 using any suitable type of electrical coupling, including, for example, an electrically conductive adhesive, an electrically conductive solder, embedding electrodes 62 in material 16, a dielectric adhesive and capacitive coupling, or the like.
  • Each electrode of plurality of electrodes 62 is electrically coupled to switch network 54 using a respective electrically conductive lead.
  • the plurality of electrodes 62 are distributed across a surface of material 16, as shown in FIG. 5.
  • the plurality of electrodes 62 may be distributed around a perimeter of material 16 (e.g., on multiple sides of material 16).
  • plurality of electrodes 62 may be referred to as a set of N electrodes 62.
  • system 50 may include one or more electrodes not electrically coupled to material 16, which may be used as a reference electrode for single-ended voltage measurements between one electrode or plurality of electrodes 62 and the reference electrode.
  • the reference electrode may be at a selected voltage, such a ground or an offset voltage.
  • the single-ended voltages may be used in the techniques described herein to determine whether material 16 includes a crack or other defect.
  • computing device 52 may determine differential voltages between two electrodes 62 electrically coupled to material 16 by comparing (e.g., subtracting) single ended voltages associated with the two electrodes, and computing device 52 may utilize these differential voltages in the techniques described herein to determine whether material 16 includes a crack or other defect.
  • Switch network 54 includes a plurality of inputs and a plurality of outputs, with respective inputs electrically coupled to each respective output by the network of switches.
  • switch network 54 may include a pair of inputs electrically coupled to electrical signal source 14, and at least a pair of inputs electrically coupled to computing device 52.
  • Switch network 54 may include at least as many outputs are there are electrodes 62.
  • system 50 includes seven electrodes, and switch network 54 thus includes at least seven outputs. Each electrode of electrodes 62 is electrically coupled to a respective output of switch network 54.
  • Computing device 52 is configured to control operation of system 50, including electrical signal source 14 and switch network 54.
  • Computing device 52 may include any of a wide range of devices, including computer servers, desktop computers, notebook (i.e., laptop) computers, tablet computers, embedded computers, and the like.
  • computing device 52 may include a processor.
  • the processor may include one or more microprocessors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other digital logic circuitry.
  • DSP digital signal processors
  • ASIC application specific integrated circuits
  • FPGA field programmable gate arrays
  • Computing device 52 is communicatively coupled to electrical signal source 14 and electrically coupled to switch network 54.
  • Computing device 52 may be configured to control electrical signal source 14 to output an electrical signal, and may be configured to control switch network 54 to couple a selected pair of electrodes from plurality of electrodes 62 to computing device 52 to serve as a pair of
  • computing device 32 may measure a magnetic field stimulation-related parameter (e.g., induced voltage or current) across material 16 in response to the electrical signal output by electrical signal source 14.
  • a magnetic field stimulation-related parameter e.g., induced voltage or current
  • Electrical signal source 14 is electrically coupled to inductor 60, which is part of support 56.
  • Support 56 provides support for inductor 60 so that inductor 60 may be positioned adjacent to material 16.
  • support 56 may define a slot 58 or other area in which material 16 may be positioned.
  • the shape of slot 58 may be complementary to the shape of material 16
  • support 56 may include one or more locating features, of the like, to facilitate positioning of material 16 relative to inductor 60.
  • support 56 is sized and shaped so that, when material 16 is positioned correctly relative to support 56, inductor 60 is contacting or nearly contacting a surface of material 16. This may result in a better signal-to-noise ratio than if inductor 60 is further from material 16.
  • Inductor 60 may include an electrical conductor arranged in any geometry suitable for an inductor.
  • inductor 60 may include a substantially planar coil, as shown in FIG. 5.
  • inductor 60 may include any number of windings.
  • Inductor 60 may include any suitable electrically conductive material, including, for example, copper, aluminum, silver, gold, or the like. Inductor 60 may be any size, and in some examples, may be sized and shaped so that a perimeter of inductor 60 is approximately the same size as a perimeter of the surface of material 16 near which inductor 60 will be positioned. This may allow relatively complete coverage of material 16 when testing for a crack or other defect. In other examples, inductor 60 may include another shape or size, such as a solenoid sized so that material 16 may be placed in the bore of the solenoid. The solenoid may have any shape, such as rectangular prism, cylindrical, elliptical cylinder, or the like.
  • support 56 may include a plurality of electrical contacts, which are arranged on support so that, when material 16 is positioned properly with respect to inductor 60, respective ones of the electrical contacts contact respective electrodes of plurality of electrodes 62. This may facilitate electrical coupling of plurality of electrodes 62 to switch network 54 and computing device 52.
  • system 50 may facilitate sequential testing of multiple samples of material 16 using the same system 50. This may be useful in manufacturing contexts, e.g., for quality control, for testing of large numbers of samples of materials 16, e.g., by an end user of material 16 after use of material 16, or the like.
  • inductor 60 may be attached to material 16, as shown in FIG. 6.
  • FIG. 6 is a conceptual and schematic diagram block illustrating another example system 70 for determining whether a material includes a crack or other defect using a magnetic field stimulation-related parameter measurement.
  • System 70 is similar to system 50 of FIG. 5, but does not include support 56. Rather, inductor 72 is mechanically attached to material 16, e.g., using an adhesive.
  • FIG. 7 is flow diagram illustrating an example technique for determining whether a material includes a crack or other defect using a magnetic field stimulation-related parameter measurement, in this case induced voltage or current.
  • the technique of FIG. 7 will be described with reference to system 50 of FIG. 5 for clarity. However, it will be appreciated that the technique of FIG. 7 may be performed by other systems and computing devices (such as system 70 of FIG. 6), and that system 50 may be used to perform other techniques.
  • the technique of FIG. 7 includes applying an electrical signal to an inductor 60 (82).
  • computing device 52 may cause electrical signal source 14 to apply the electrical signal to inductor 60 (82).
  • the electrical signal may include an AC voltage or current.
  • Computing device 52 also may control electrical signal source 14 to generate the AC voltage or current with a selected amplitude, duration, frequency, phase, and other signal characteristics.
  • the technique of FIG. 7 also includes, while applying the electrical signal to inductor 60, measuring a respective induced voltage or current between a respective pair of electrodes 62 electrically coupled to material 16 (84).
  • computing device 52 may cause switch network 54 to electrically couple computing device 52 to a selected pair of electrodes from plurality of electrodes 62.
  • the selected pair of electrodes may be any two electrodes from plurality of electrodes 62.
  • the two electrodes in the selected pair of electrodes may be directly adjacent to each other with no other electrodes in between.
  • the two electrodes in the selected pair of electrodes may be spaced apart from each other with one or more electrodes in between.
  • computing device 52 may measure a respective induced voltage or current across the selected pair of electrodes (84) while electrical signal source 14 is applying the electrical signal to inductor 60 (82).
  • computing device 32 may be configured to measure a respective magnetic field stimulation-related parameter for a plurality of pairs of electrodes from electrodes 62.
  • the technique of FIG. 7 further includes determining whether there is an additional pair of electrodes at which to measure a respective induced voltage or current (86).
  • each pair of measurement electrodes is a unique pair of electrodes.
  • no two pairs of measurement electrodes share a common electrode.
  • a first pair of electrodes may not share any electrodes with a second, different pair of electrodes.
  • different pairs of electrodes may include one common electrode.
  • a first pair of electrodes may share exactly one electrode with a second, different electrode pair.
  • computing device 52 may control switch network 54 to couple the selected additional pair of electrodes to computing device 52.
  • Computing device 52 then may measure the induced voltage or current across the selected additional pair of electrodes (84).
  • Computing device 52 may repeat this determination (86), coupling of a selected pair of electrodes, and measurement of a respective induced voltage or current across the selected pair of electrodes (84) until computing device 52 determines there are no more additional pairs of electrodes from plurality of electrodes 62 to be used as a pair of measurement electrodes
  • computing device 52 may determine whether material 16 includes a crack or other defect based on the respective induced voltages or currents (88). In some examples, computing device 52 may determine whether material 36 includes a crack or other defect based on a comparison between respective induced voltages or currents. For example, computing device 52 or another computing device may perform steps (82)-(86) of the technique of FIG. 7 on material 16 at a first time at which it is known that material 16 is intact, i.e., does not include a crack or other defect.
  • the first time may be a time at which material 16 is manufactured, or a time at which an independent measurement (e.g., X-ray radiology or X-ray CT scan) may be used to verify that material 16 is intact, undamaged, or does not include a crack.
  • computing device 52 or another device may determine the control induced voltages or currents using a model of material 16 in an intact (undamaged) state, or computing device 12 or another device may determine the control induced voltages or currents as an average (e.g., mean) of a plurality of similar materials (e.g., in geometry and composition) that are known to be intact (undamaged).
  • control induced voltages or current may be stored (e.g., in a memory device associated with computing device 52) for later use.
  • the respective control induced voltages or currents may be stored in a data structure in which each respective control induced voltage or current is associated with a pair of electrodes with which the respective control induced voltage or current was measured.
  • Computing device 52 may compare the respective measured induced voltages or currents to respective control induced voltages or currents and determine whether material 16 includes the crack or other defect based on the comparison. For example, computing device 52 may compare each respective measured induced voltage or current with a corresponding (i.e., associated with the same pair of electrodes) control induced voltage or current. As an example, computing device 52 may subtract the respective measured induced voltage or current from the corresponding control induced voltage or current. In some examples, computing device 52 may compare the respective induced voltage or current difference (between the respective measurement induced voltage or current and the respective control induced voltage or current) to a threshold difference value.
  • the threshold difference value may be selected so that an induced voltage or current difference above the threshold difference value is meaningful (e.g., indicative of a crack or other defect) and an induced voltage or current difference below the threshold difference value is not meaningful (e.g., is not indicative of a crack or other defect).
  • the threshold difference value may be selected to be a difference value that is slightly greater than a noise floor of the measurement, such that any induced voltage or current difference that exceeds the noise floor is determined by computing device 52 to be indicative of a crack or other defect.
  • computing device 52 may determine whether a crack or other defect is present in material 16 based on the plurality of indications. For example, computing device 52 may determine a number of differences that are indicative of a crack and compare this number of differences to a threshold number of differences to determine if material 16 includes a crack or other defect. As another example, computing device 52 may determine that material 16 includes a crack of other defect in response to at least one respective magnetic field stimulation-related parameter difference being greater than the threshold magnetic field stimulation-related parameter.
  • computing device 52 may compare the measured induced voltages or currents to a predetermined threshold induced voltage or current.
  • the predetermined induced voltage or current threshold may be selected so that a measured induced voltage or current below the threshold induced voltage or current value is indicative of a crack or other defect and a measured induced voltage or current above the threshold induced voltage or current value is not indicative of a crack or other defect.
  • computing device 52 may calculate an approximate impedance distribution utilizing the respective control induced voltages or currents, and the respective measured induced voltages or currents to determine whether material 16 includes a crack or other defect (88).
  • reconstruction of the impedance distribution may be achieved by minimizing difference between the output of a physics-based simulation tool with the respective control voltages, and the respective measurement voltages.
  • computing device 52 may be programmed with a finite element model (FEM) of material 16 which implements the physics-based simulation.
  • FEM finite element model
  • the FEM of material 16 may include substantially accurate (e.g., accurate or approximately accurate) geometry of material 16 (e.g., the shape and volume of material 16), and also may include substantially accurate (e.g., accurate or approximately accurate) locations of electrodes 38 attached to material 36 and position of inductor 60 relative to material 16.
  • the FEM of material 16 may additionally include representative properties of material 16, including, for example, conductivity, resistivity, other related electrical properties, and the like.
  • the FEM of material 16 may include representative properties of material 16 for each respective node representing material 16.
  • Calculating the approximate impedance distribution to determine whether material 16 includes a crack of other defect is an ill-posed inverse problem, in which the outputs (the respective measurement voltages) are known but the properties of material 16 that produce the outputs are unknown. Moreover, more than one set of properties of material 16 may produce the outputs. Hence, computing device 52 may utilize a regularization technique to constrain the solution to solutions more likely to represent the properties of material 16 that would produce the respective measurement voltages.
  • computing device 52 may generate an objective function which combines outputs of the physics-based model, respective control voltages, the respective measurement voltages, and the regularization term. For example: ar where x is the approximate change in impedance distribution, f is an operator calculating the simulated difference in voltages based on input x utilizing the physics-based simulation, y is the measured difference in voltages, h is a chosen norm, R is the regularization matrix, and ⁇ is the chosen weight of the regularization or regularization parameter. Computing device 52 may determine respective model control voltages based on the physics-based model and inputs representative of the electrical signal(s) applied to inductor 60. The respective model control voltages may be associated with respective pairs of measurement electrodes used to collect the control voltages from material 16.
  • Computing device 52 may determine, using the physics-based model and inputs representative of the electrical signal(s) applied to inductor 60, respective model measurement voltages.
  • the respective model measurement voltages may be associated with respective pairs of measurement electrodes used to collect the measurement voltages from material 16.
  • computing device 52 may determine a respective difference between the respective model measurement voltage and the respective model control voltage (f(x) in the equation above).
  • Computing device 52 also may determine a respective difference between the respective measurement voltage and the respective control voltage for each respective measurement voltage measured using material 16 to generate a set of actual voltage differences (y in the equation above).
  • Computing device 52 then may minimize the objective function by updating one or more parameters of the physics-based model. Computing device 52 may continue to iterate the model until a stopping criterion is reached. Computing device 52 then may determine the approximate impedance distribution (or approximate change in impedance distribution) that is representative of the condition of material 16. When iteration completes the input to the model is the approximate impedance distribution.
  • Computing device 52 may then determine whether material 16 includes a crack or other defect based on the approximate change in impedance distribution. For example, computing device 52 may determine whether material 16 includes a crack or other defect based on the magnitude and location of the approximate impedance change within the material. In some examples, only the real portion of the impedance— the conductivity or resistivity— may be used by computing device 52 to determine whether material 16 includes a crack or other defect.
  • computing device 52 may determine an approximate impedance distribution using an absolute form of the objective function, in which x is the impedance distribution, f is an operator calculating a set of the simulated voltages based on input x utilizing the physics-based simulation, y is a set of the measured voltages, h is a chosen norm, R is the regularization matrix, and ⁇ is the chosen weight of the regularization or regularization parameter.
  • Computing device 52 may output a representation of the determination of whether material 16 includes a crack or other defect.
  • the representation may include a simplified output, such as an indication of ' es" or “No,” “Crack” or “No Crack,” “Damaged” or “Intact,” or the like.
  • the representation may be textual, icon-based, color-based, or the like.
  • the representation may include a green light to represent that material 16 is still intact or a red light to represent that material 16 is damages or includes a crack or other defect.
  • computing device 52 may output a visual representation of the
  • computing device 52 may output a visual representation of material 16 and locations of the crack or other defect. For example, computing device 52 may output a false-color representation of the inductor-related parameter overlaid on a representation of material 16.
  • a magnetic field stimulation-related parameter measurement may facilitate detection of cracks or other defects in a material utilizing relatively smaller, relatively less expensive equipment, which may be portable and be used to detect cracks in materials in situ rather than requiring removing the materials to be tested to the testing equipment. Additionally or alternatively, a magnetic field stimulation-related parameter measurement crack detection system may allow relatively
  • processors including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components.
  • DSPs digital signal processors
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays
  • processors may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry.
  • a control unit including hardware may also perform one or more of the techniques of this disclosure.
  • Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various techniques described in this disclosure.
  • any of the described units, modules or components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware, firmware, or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware, firmware, or software components, or integrated within common or separate hardware, firmware, or software components.
  • the techniques described in this disclosure may also be embodied or encoded in an article of manufacture including a computer-readable storage medium encoded with instructions. Instructions embedded or encoded in an article of manufacture including a computer-readable storage medium encoded, may cause one or more programmable processors, or other processors, to implement one or more of the techniques described herein, such as when instructions included or encoded in the computer- readable storage medium are executed by the one or more processors.
  • Computer readable storage media may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a compact disc ROM (CD- ROM), a floppy disk, a cassette, magnetic media, optical media, or other computer readable media.
  • RAM random access memory
  • ROM read only memory
  • PROM programmable read only memory
  • EPROM erasable programmable read only memory
  • EEPROM electronically erasable programmable read only memory
  • flash memory a hard disk, a compact disc ROM (CD- ROM), a floppy disk, a cassette, magnetic media, optical media, or other computer readable media.
  • an article of manufacture may include one or more computer-readable storage media.
  • a computer-readable storage medium may include a non-transitory medium.
  • the term "non-transitory” may indicate that the storage medium is not embodied in a carrier wave or a propagated signal.
  • a non-transitory storage medium may store data that can, over time, change (e.g., in RAM or cache).
  • Clause 1 A method for detecting a crack or defect in a material, the method comprising:
  • Clause 2 The method of clause 1, wherein determining whether the material includes the crack or other defect based on the electrical loss comprises determining that the material includes the crack or other defect in response to the electrical loss being less than a threshold electrical loss value.
  • Clause 3 The method of clause 1, wherein determining whether the material includes the crack or other defect based on the electrical loss comprises determining that the material includes the crack or other defect in response to the electrical loss being less than a control electrical loss.
  • Clause 4 The method of any one of clauses 1 to 3, wherein: the inductor comprises a first inductor; the electrical loss comprises a first electrical loss; the method further comprises: applying the electrical signal to a second inductor adjacent to the material; and determining a second electrical loss in the second inductor due to the material; and determining whether the material includes the crack or other defect comprises determining whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss.
  • Clause 5 The method of clause 4, wherein determining whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss comprises determining that the material includes the crack or other defect in response to the first electrical loss being different than the second electrical loss.
  • Clause 6 The method of clause 4, wherein determining whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss comprises: determining that the material includes the crack or other defect in response to at least one of the first electrical loss or the second electrical loss being less than a threshold electrical loss value.
  • Clause 7 The method of clause 4, wherein determining whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss comprises: determining that the material includes the crack or other defect in response to at least one of the first electrical loss being less than a first control electrical loss or the second electrical loss being less than a second control electrical loss.
  • Clause 8 The method of any one of clauses 1 to 7, wherein the inductor comprises at least two inductors electrically coupled in series.
  • Clause 9 The method of any one of clauses 1 to 8, wherein the material comprises at least one of a semiconductive ceramic material, an electrically conductive ceramic material, or a magnetically permeable material.
  • Clause 10 The method of clause 9, wherein the material comprises a semiconductive ceramic armor piece or an electrically conductive ceramic armor piece.
  • a system comprising: a material; an inductor adjacent to the material; an electrical signal source configured to apply an electrical signal to the at least one inductor; and a computing device configured to: determine an electrical loss in the inductor due to the material; and determine whether the material includes a crack or other defect based on the electrical loss.
  • Clause 12 The system of clause 11, wherein the computing device is configured to determine whether the material includes the crack or other defect in response to the electrical loss being less than a threshold electrical loss value.
  • Clause 13 The system of clause 11, wherein the computing device is configured to determine whether the material includes the crack or other defect in response to the electrical loss being less than a control electrical loss.
  • Clause 14 The system of any one of clauses 11 to 13, wherein: the inductor comprises a first inductor; the electrical loss comprises a first electrical loss; the electrical signal source is further configured to applying the electrical signal to a second inductor adjacent to the material; and the computing device is further configured to: determine a second electrical loss in the second inductor due to the material; and determine whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss.
  • Clause 15 The system of clause 14, wherein the computing device is configured to determine whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss in response to the first electrical loss being different than the second electrical loss.
  • Clause 16 The system of clause 14, wherein the computing device is configured to determine whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss in response to at least one of the first electrical loss or the second electrical loss being less than a threshold electrical loss value.
  • Clause 17 The system of clause 14, wherein the computing device is configured to determine whether the material includes the crack or other defect based on the first electrical loss and the second electrical loss in response to at least one of the first electrical loss being less than a first control electrical loss or the second electrical loss being less than a second control electrical loss.
  • Clause 18 The system of any one of clauses 11 to 17, wherein the inductor comprises at least two inductors coupled in series.
  • Clause 19 The system of any one of clauses 11 to 18, wherein the material comprises at least one of a semiconductive ceramic material, an electrically conductive ceramic material, or a magnetically permeable material.
  • Clause 20 The system of clause 19, wherein the material comprises a semiconductive ceramic armor piece or an electrically conductive ceramic armor piece.
  • a system comprising: an electrical signal source; an inductor electrically coupled to the electrical signal source; a pair of electrical contacts; and a computing device configured to: cause the electrical signal source to apply an electrical signal to the inductor when a material is adjacent to the inductor; determine an induced voltage or current across the pair of electrical contacts, wherein the electrical contacts are electrically coupled to a pair of electrodes electrically coupled to the material, and wherein at least one electrode of the pair of electrodes is; determine whether the material includes a crack or other defect based on the induced voltage or current.
  • Clause 22 The system of clause 21, further comprising the material and the pair of electrodes electrically and mechanically coupled to the material, each respective electrode electrically contacting a respective electrical contact of the pair of electrical contacts, and wherein the material comprises at least one of a semiconductive ceramic material, an electrically conductive ceramic material, or a magnetically permeable material.
  • Clause 23 The system of clause 22, wherein the material comprises a semiconductive ceramic armor piece or an electrically conductive ceramic armor piece.
  • Clause 24 The system of any one of clauses 21 to 23, wherein the computing device is configured to determine whether the material includes the crack or other defect based on the induced voltage or current by at least comparing the induced voltage or current to a control induced voltage or current.
  • Clause 25 The system of any one of clauses 21 to 24, wherein: the pair of electrical contacts comprises a plurality of electrical contacts; and the computing device is further configured to: determine a respective induced voltage or current between each respective pair of electrical contacts of a plurality of unique pairs of electrical contacts while applying the electrical signal to the inductor; and determine whether the material includes the crack or other defect based on the respective induced voltages or currents.
  • Clause 26 The system of clause 25, further comprising the material, and wherein: a plurality of electrodes are distributed across a surface area of the material and are positioned on the material to electrically contact a respective electrical contact of the plurality of electrical contacts.
  • Clause 27 The system of clause 25, further comprising the material, and wherein: a plurality of electrodes are distributed around a perimeter of the material and are positioned on the material to electrically contact a respective electrical contact of the plurality of electrical contacts.
  • Clause 28 The system of any one of clauses 25 to 27, wherein the computing device is configured to determine whether the material includes the crack or other defect by at least comparing the respective induced voltages or currents to respective control induced voltages or currents.
  • Clause 29 The system of any one of clauses 25 to 28, wherein the computing device is configured to determine whether the material includes the crack or other defect based on the respective induced voltages or currents by at least: calculating an approximate change in impedance distribution within the material based on a physics-based simulation, inputs representative of the electrical signal(s) applied to the inductor, the respective induced voltages or currents, and respective control induced voltages or currents; and determining that the material includes the crack or other defect based on the approximate change in the impedance distribution.
  • Clause 30 The system of clause 29, wherein calculating the approximate change in impedance
  • x is the approximate change in impedance distribution
  • f is an operator calculating a set of simulated differences in induced voltages or currents based on input x utilizing the physics-based simulation
  • y is a set of differences between the respective induced voltages or currents and the respective control induced voltages or currents
  • R is a regularization matrix
  • ⁇ is a chosen weight of the regularization or a regularization parameter.
  • Clause 31 The system of any one of clauses 21 to 30, wherein the inductor is mechanically attached to the material.
  • Clauses 32 The system of any one of clauses 21 to 30, wherein the inductor is not mechanically attached to the material.
  • Clause 33 A method comprising: applying an electrical signal to an inductor adjacent to a material; determining an induced voltage or current across a pair of electrical contacts, wherein at least one of the electrical contacts is electrically coupled to the material; and determining whether the material includes a crack or other defect based on the induced voltage or current.
  • Clause 34 The method of clause 33, further comprising the material and a pair of electrodes, wherein at least one electrode of the pair of electrodes is electrically and mechanically coupled to the material, each respective electrode positioned to electrically contact a respective electrical contact of the pair of electrical contacts, and wherein the material comprises at least one of a semiconductive ceramic material, an electrically conductive ceramic material, or a magnetically permeable material.
  • Clause 35 The method of clause 34, wherein the material comprises a semiconductive ceramic armor piece or an electrically conductive ceramic armor piece.
  • Clause 36 The method of any one of clauses 33 to 35, wherein determining whether the material includes the crack or other defect based on the induced voltage or current comprises determining whether the material includes the crack or other defect by at comparing the induced voltage or current to a control induced voltage or current.
  • Clause 37 The method of any one of clauses 33 to 38, wherein: the pair of electrical contacts comprises a plurality of electrical contacts; and the method further comprises: determining a respective induced voltage or current between each respective pair of electrical contacts of a plurality of unique pairs of electrical contacts while applying the electrical signal to the inductor; and determining whether the material includes the crack or other defect based on the respective induced voltages or currents.
  • Clause 38 The method of clause 37, further comprising the material, and wherein: a plurality of electrodes are distributed across a surface area of the material and are positioned on the material to electrically contact a respective electrical contact of the plurality of electrical contacts.
  • Clause 39 The method of claim 37, further comprising the material, and wherein: a plurality of electrodes are distributed around a perimeter of the material and are positioned on the material to electrically contact a respective electrical contact of the plurality of electrical contacts.
  • Clause 40 The method of any one of clauses 37 to 39, wherein determining whether the material includes the crack or other defect comprises comparing the respective induced voltages or currents to respective control induced voltages or currents.
  • Clause 41 The system of any one of clauses 37 to 40, wherein determining whether the material includes the crack or other defect based on the respective induced voltages or currents comprises:
  • Clause 42 The method of claim 41, wherein calculating the approximate change in impedance distribution within the material comprises minimizing an output of an objective function: wherein x is the approximate change in impedance distribution, f is an operator calculating a set of simulated differences in induced voltages or currents based on input x utilizing the physics-based simulation, y is a set of differences between the respective induced voltages or currents and the respective control induced voltages or currents, h is a chosen norm, R is a regularization matrix, and ⁇ is a chosen weight of the regularization or a regularization parameter.
  • Clause 43 The method of any one of clauses 33 to 42, wherein the inductor is mechanically attached to the material.
  • Clause 44 The method of any one of clauses 33 to 42, wherein the inductor is not mechanically attached to the material.

Landscapes

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

Abstract

L'invention concerne des techniques et des systèmes visant à détecter une fissure ou un défaut dans un matériau. Dans certains exemples, un procédé de détection d'une fissure ou d'un défaut dans un matériau peut comprendre l'application d'un signal électrique à un inducteur adjacent au matériau ; la détermination d'une perte électrique dans l'inducteur du fait du matériau ; et la détermination de la présence ou pas d'une fissure ou d'un autre défaut dans le matériau sur la base de la perte électrique. Dans d'autres exemples, un procédé de détection d'une fissure ou d'un défaut dans un matériau peut comprendre l'application d'un signal électrique à un inducteur adjacent à un matériau ; la détermination d'une tension ou d'un courant induit à travers une paire de contacts électriques, au moins l'un des contacts électriques étant électriquement relié au matériau ; et la détermination de la présence ou pas d'une fissure ou d'un autre défaut dans le matériau sur la base de la tension ou du courant induit.
PCT/US2017/061737 2016-11-16 2017-11-15 Vérification de l'intégrité structurale de matériaux par stimulation par champ magnétique Ceased WO2018093855A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201662422933P 2016-11-16 2016-11-16
US62/422,933 2016-11-16

Publications (1)

Publication Number Publication Date
WO2018093855A1 true WO2018093855A1 (fr) 2018-05-24

Family

ID=62145796

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2017/061737 Ceased WO2018093855A1 (fr) 2016-11-16 2017-11-15 Vérification de l'intégrité structurale de matériaux par stimulation par champ magnétique

Country Status (1)

Country Link
WO (1) WO2018093855A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102021117043A1 (de) 2021-07-01 2022-08-11 Carl Zeiss Smt Gmbh Verfahren zum zerstörungsfreien Prüfen eines keramischen Bauteils

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4785243A (en) * 1987-01-29 1988-11-15 Ltv Steel Company Electronically scanned eddy current flaw inspection
US6150809A (en) * 1996-09-20 2000-11-21 Tpl, Inc. Giant magnetorestive sensors and sensor arrays for detection and imaging of anomalies in conductive materials
US7705589B2 (en) * 2008-02-19 2010-04-27 Korea Research Institute Of Standards And Science Sensor for detecting surface defects of metal tube using eddy current method
US20110060536A1 (en) * 2009-09-09 2011-03-10 Maria Qing Feng Method and Apparatus for Inspecting Crack in Ceramic Body
CN101832970B (zh) * 2010-05-07 2012-08-29 江苏大学 交流电位法测算平板合金疲劳裂纹扩展速率的装置和方法
US20150308980A1 (en) * 2012-12-31 2015-10-29 Halliburton Energy Services, Inc. Apparatus and method of defects inspection
CN205003121U (zh) * 2015-09-22 2016-01-27 杭州浙达精益机电技术股份有限公司 一种用于钢轨轨底缺陷检测的磁致伸缩式剪切导波换能器

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4785243A (en) * 1987-01-29 1988-11-15 Ltv Steel Company Electronically scanned eddy current flaw inspection
US6150809A (en) * 1996-09-20 2000-11-21 Tpl, Inc. Giant magnetorestive sensors and sensor arrays for detection and imaging of anomalies in conductive materials
US7705589B2 (en) * 2008-02-19 2010-04-27 Korea Research Institute Of Standards And Science Sensor for detecting surface defects of metal tube using eddy current method
US20110060536A1 (en) * 2009-09-09 2011-03-10 Maria Qing Feng Method and Apparatus for Inspecting Crack in Ceramic Body
CN101832970B (zh) * 2010-05-07 2012-08-29 江苏大学 交流电位法测算平板合金疲劳裂纹扩展速率的装置和方法
US20150308980A1 (en) * 2012-12-31 2015-10-29 Halliburton Energy Services, Inc. Apparatus and method of defects inspection
CN205003121U (zh) * 2015-09-22 2016-01-27 杭州浙达精益机电技术股份有限公司 一种用于钢轨轨底缺陷检测的磁致伸缩式剪切导波换能器

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
RUAN, T, DEVELOPMENT OF AN AUTOMATED IMPEDANCE TOMOGRAPHY SYSTEM AND ITS IMPLEMENTATION IN CEMENTITIOUS MATERIALS, August 2016 (2016-08-01), pages 46 - 47, Retrieved from the Internet <URL:https://tigerprints.clemson.edu/cgi/viewcontent.cgi?article-2758&contoxt-all_dissertations> [retrieved on 20180220] *
ZAOUI, A ET AL.: "Inverse Problem in Nondestructive Testing Using Arrayed tddy Current Sensors", SENSORS, vol. 10, 10 September 2010 (2010-09-10), pages 8696 - 8707, XP055486028 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102021117043A1 (de) 2021-07-01 2022-08-11 Carl Zeiss Smt Gmbh Verfahren zum zerstörungsfreien Prüfen eines keramischen Bauteils

Similar Documents

Publication Publication Date Title
US11609202B2 (en) Electrode placement for verifying structural integrity of materials
US11946891B2 (en) Temperature-corrected control data for verifying of structural integrity of materials
US11609203B2 (en) Suppressing thermally induced voltages for verifying structural integrity of materials
CN101460808A (zh) 确定在导电基底上导电涂层的层厚的方法
US11255807B2 (en) Verifying structural integrity of materials
JP2016524138A (ja) 電磁特性を計測する装置及び方法
US11150209B2 (en) Verifying structural integrity of materials using electrical properties
US7443177B1 (en) Characterization of conductor by alternating current potential-drop method with a four-point probe
EP3555606B1 (fr) Controle de l&#39;integrite structurelle d&#39;un materiau moyennant une impedance de reference
CN105319444B (zh) 一种导电材料电导率均匀程度评估方法
WO2018093863A2 (fr) Vérification de l&#39;intégrité structurelle de matériaux à l&#39;aide de mesures de paramètres réactifs
EP3555607A2 (fr) Vérification de l&#39;intégrité structurale de matériaux
Ma et al. Pipelines inspection using magnetic induction tomography based on a narrowband pass filtering method
WO2018093855A1 (fr) Vérification de l&#39;intégrité structurale de matériaux par stimulation par champ magnétique
WO2018093871A1 (fr) Procédé et appareil pour la détection d&#39;une fissure ou d&#39;un défaut dans un matériau conducteur ou semi-conducteur
US11181498B2 (en) Temperature-independent verifying of structural integrity of materials using electrical properties
Gordon et al. Eddy current validation of Euro-coins
WO2018093906A1 (fr) Vérification de l&#39;intégrité structurale de matériaux à l&#39;aide de multiples points d&#39;injection de courant et d&#39;un ou plusieurs points d&#39;extraction de courant
Sheldon et al. An interdigital capacitive sensor for quantitative characterization of wire insulation
Martens et al. High-accuracy eddy current measurements of metals
Hu Imaging of hidden objects by planar capacitive and magnetic sensor arrays for security applications
WO2018093882A1 (fr) Vérification de l&#39;intégrité structurale de matériaux à l&#39;aide d&#39;un ou plusieurs points d&#39;injection de courant et de multiples points d&#39;extraction de courant
Sheldon Electrical and capacitive methods for detecting degradation in wire insulation
Bettini et al. Direct and inverse electromagnetic methodologies: the proposal of MADEND project for ECT analysis
Chady et al. Multilayer transducer for impulse eddy current testing system

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17872696

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17872696

Country of ref document: EP

Kind code of ref document: A1