# US 2019/0170677 A1 · Method for non-intrusively detecting imperfections in a test object > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170677 A1 - Document ID: US20190170677A1 - Status: Published application - Kind: A1 - Application number: 16/156,172 - Filed: 2018-10-10 - Published: 2019-06-06 - Earliest claimed: 2017-12-05 - Assignees: Airbus Helicopters - Applicants: Airbus Helicopters - Inventors: Laurent BIANCHI; Sebastien BERNIER; John ENDERBY; Mark BOWES; Dawood PARKER - Web page: https://patentgrep.com/patent/US20190170677A1 ## CPC - G01N 27/24: Investigating the presence of flaws - G01N 27/221: {by investigating the dielectric properties (using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26)} - G01N 27/9046: {by analysing electrical signals} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method for non-intrusively detecting imperfections in a test object made from metallic, non-conductive, and/or composite materials. The method uses a database with predetermined reference values and a probe that comprises a capacitive measuring apparatus with at least two coplanar electrodes. The method includes the operations of placing the at least two coplanar electrodes into a first position that is at a predetermined distance from the test object, performing a capacitive measurement to determine an effective dielectric constant, retrieving a reference value of the predetermined reference values from the database based on the test object and the predetermined distance, and detecting imperfections in the test object based on a comparison of the effective dielectric constant with the reference value. ## Claims ### Claim 1 A method for non-intrusively detecting imperfections in a test object made from metallic, non-conductive, and/or composite materials, using a database with predetermined reference values and a probe that comprises a capacitive measuring apparatus with at least two coplanar electrodes, the method comprising: placing the at least two coplanar electrodes into a first position that is at a predetermined distance from the test object, performing a capacitive measurement to determine an effective dielectric constant, retrieving a reference value of the predetermined reference values from the database based on the test object and the predetermined distance, and detecting imperfections in the test object based on a comparison of the effective dielectric constant with the reference value. ### Claim 2 (depends on 1) The method of claim 1, wherein performing the capacitive measurement further comprises: driving one of the at least two coplanar electrodes with an oscillating voltage, and measuring an electric charge that is transferred between the at least two coplanar electrodes. ### Claim 3 (depends on 2) The method of claim 2, wherein performing the capacitive measurement further comprises: determining a capacitance between the at least two coplanar electrodes based on the measured electric charge, and determining the effective dielectric constant based on the capacitance and the test object. ### Claim 4 (depends on 1) The method of claim 1, wherein detecting imperfections in the test object based on the comparison of the effective dielectric constant with the reference value further comprises: determining whether the effective dielectric constant is different than the retrieved reference value, in response to determining that the effective dielectric constant is not different than the retrieved reference value, determining an absence of measurable imperfections in the test object, and in response to determining that the effective dielectric constant is different than the retrieved reference value, determining a presence of an imperfection in the test object. ### Claim 5 (depends on 1) The method of claim 1, further comprising: moving the at least two coplanar electrodes relative to the test object from the first position into a second position that is at the predetermined distance from the test object. ### Claim 6 (depends on 5) The method of claim 5, further comprising: using a separation device to maintain the predetermined distance when moving the at least two coplanar electrodes relative to the test object from the first position into the second position. ### Claim 7 (depends on 5) The method of claim 5, wherein the at least two coplanar electrodes have the shape of disks that are mounted on a roller, and wherein a step is moving at least two coplanar electrodes relative to the test object from the first position into a second position further comprises: using a roller to roll the at least two coplanar electrodes over a surface of the test object. ### Claim 8 (depends on 6) The method of claim 6, further comprising: determining an additional effective dielectric constant at the second position. ### Claim 9 (depends on 8) The method of claim 8, further comprising: moving the at least two coplanar electrodes from the second position into a third position that is at the predetermined distance from the test object. ### Claim 10 (depends on 9) The method of claim 9, further comprising: adjusting a spatial separation of the at least two coplanar electrodes relative to each other to emulate a variation in the predetermined distance between the at least two coplanar electrodes and the test object. ### Claim 11 (depends on 9) The method of claim 9, further comprising: determining a second additional effective dielectric constant at the third position. ### Claim 12 (depends on 11) The method of claim 11, further comprising: determining a shape of the imperfection in the test object based on the effective dielectric constant, the additional dielectric constant, and the second additional dielectric constant. ### Claim 13 (depends on 11) The method of claim 11, further comprising: determining a location of the imperfection in the test object based on the first, second, and third positions. ### Claim 14 (depends on 1) The method of claim 1, wherein determining the effective dielectric constant further comprises: determining a real part and an imaginary part of a complex dielectric constant based on the capacitive measurement. ### Claim 15 (depends on 1) The method of claim 1, further comprising: selecting a reference test object without defects, performing another capacitive measurement to determine a reference effective dielectric constant, storing the reference effective dielectric constant as one of the predetermined reference values in the database.