# US 9,038,469 B2 · Reference free inconsistency detection system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,469 B2 - Document ID: US9038469B2 - Status: Granted - Kind: B2 - Application number: 13/312,341 - Filed: 2011-12-06 - Published: 2013-06-06 - Granted: 2015-05-26 - Earliest claimed: 2011-12-06 - Assignees: The Boeing Company - Applicants: Hoon Sohn; Hyung Jin Lim; Chul Min Yeum; Jeong-Beom Ihn - Inventors: Hoon Sohn; Hyung Jin Lim; Chul Min Yeum; Jeong-Beom Ihn - Web page: https://patentgrep.com/patent/US9038469B2 ## CPC - G01N 29/043: {in the interior, e.g. by shear waves} - G01N 29/07: by measuring propagation velocity or propagation time of acoustic waves - G01N 29/4454: {Signal recognition, e.g. specific values or portions, signal events, signatures} - G01N 29/4472: {Mathematical theories or simulation} - G01N 2291/0231: Composite or layered materials - G01N 2291/044: Internal reflections (echoes), e.g. on walls or defects - G01N 2291/2694: Wings or other aircraft parts - 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 and apparatus for identifying an inconsistency. A number of waves that propagate through a structure are generated. A response signal is generated in response to detecting at least a portion of the number of waves that propagate through the structure. A determination is made as to whether the response signal includes a reflected component. A presence of the inconsistency in the structure is indicated when the response signal includes the reflected component. ## Claims ### Claim 1 A method for identifying an inconsistency, the method comprising: generating a number of waves that propagate through a structure; generating a response signal in response to detecting at least a portion of the number of waves that propagate through the structure; determining whether the response signal includes a reflected component; indicating a presence of the inconsistency in the structure when the response signal includes the reflected component; and identifying information about the inconsistency by identifying an m value, wherein the m value is half of a product of a central frequency for the number of waves and a difference in arrival time of a transmitted portion and a reflected portion of the at least a portion of the number of waves detected. ### Claim 2 (depends on 1) The method of claim 1, wherein the at least a portion of the number of waves is detected in one of a pitch-catch mode and a pulse-echo mode. ### Claim 3 (depends on 1) The method of claim 1, wherein determining whether the response signal includes the reflected component comprises: identifying a number of components in the response signal; and determining whether the number of components in the response signal includes the reflected component. ### Claim 4 (depends on 1) The method of claim 1 further comprising: identifying information about the inconsistency using the difference in arrival time of the transmitted portion and the reflected portion of the at least a portion of the number of waves detected. ### Claim 5 (depends on 4) The method of claim 4, wherein the information includes at least one of a size of the inconsistency, an indice for the inconsistency, and a range of possible values for a length of the inconsistency. ### Claim 6 (depends on 4) The method of claim 4, wherein the waves are generated using a first transducer positioned relative to the structure and the response signal is generated using a second transducer positioned relative to the structure in which the inconsistency is located between the first transducer and the second transducer and wherein identifying the information about the inconsistency comprises: identifying an upper limit for a range of possible values for a length of the inconsistency using a first time when the transmitted portion was detected and a second time when the reflected portion was detected and a distance between the first transducer and the second transducer. ### Claim 7 (depends on 4) The method of claim 4, wherein identifying the information about the inconsistency further comprises: identifying a range of possible values for a length of the inconsistency using the m value, a first velocity for the reflected portion through the inconsistency, the central frequency, and an assumption that the first velocity for the reflected portion is lower than a second velocity for the transmitted portion through an area in the structure in which the inconsistency is not present. ### Claim 8 (depends on 1) The method of claim 1, wherein the m value indicates a level of severity of the inconsistency with respect to stiffness. ### Claim 9 (depends on 1) The method of claim 1, wherein generating the number of waves that propagate through the structure comprises: generating a number of Lamb waves that propagate through the structure using a transducer configured to function as a transmitter. ### Claim 10 (depends on 9) The method of claim 9, wherein generating the number of Lamb waves comprises: exciting an asymmetric zero order wave mode for the number of Lamb waves that propagate through the structure using the transducer configured to function as the transmitter. ### Claim 11 (depends on 1) The method of claim 1, wherein the structure is for a platform, and the platform is an aircraft. ### Claim 12 An apparatus comprising: a transducer system configured to be associated with a structure and configured to generate a number of waves that propagate through the structure and generate a response signal in response to detecting at least a portion of the number of waves that propagate through the structure; and an analyzer configured to: control the transducer system to receive the response signal from the transducer system; determine whether the response signal includes a reflected component; indicate a presence of an inconsistency in the structure when the response signal includes the reflected component; and identify information about the inconsistency by identifying an m value, wherein the m value is half of a product of a central frequency for the number of waves and a difference in arrival time of a transmitted portion and a reflected portion of the at least a portion of the number of waves detected. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the transducer system is further configured to detect the at least a portion of the number of waves in one of a pitch-catch mode and a pulse-echo mode. ### Claim 14 (depends on 12) The apparatus of claim 12, wherein in being configured to determine whether the response signal includes the reflected component, the analyzer is configured to identify a number of components in the response signal; and determine whether the number of components in the response signal includes the reflected component. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the analyzer is further configured to identify information about the inconsistency using the difference in arrival time of the transmitted portion and the reflected portion of the at least a portion of the number of waves detected in which the information includes at least one of a size of the inconsistency, an indice for the inconsistency, and a range of possible values for a length of the inconsistency. ### Claim 16 (depends on 12) The apparatus of claim 12, wherein the transducer system comprises: a first transducer configured to be positioned relative to the structure and configured to generate the number of waves; and a second transducer configured to be positioned relative to the structure and configured to generate the response signal, wherein the inconsistency is located between the first transducer and the second transducer. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein in being configured to identify the information about the inconsistency, the analyzer is configured to identify the range of possible values for the length of the inconsistency using the m value, a first velocity for the reflected portion through the inconsistency, the central frequency, and an assumption that the first velocity for the reflected portion is lower than a second velocity for the transmitted portion through an area in the structure in which the inconsistency is not present. ### Claim 18 (depends on 12) The apparatus of claim 12, wherein the m value indicates a level of severity of the inconsistency with respect to stiffness. ### Claim 19 (depends on 12) The apparatus of claim 12, wherein the number of waves takes a form of a number of Lamb waves and wherein the transducer system is configured to excite an asymmetric zero order wave mode for the number of Lamb waves to generate the number of Lamb waves that propagate through the structure.