# US 10,768,128 B2 · Systems and methods of monitoring a thermal protection system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,128 B2 - Document ID: US10768128B2 - Status: Granted - Kind: B2 - Application number: 14/337,622 - Filed: 2014-07-22 - Published: 2016-01-28 - Granted: 2020-09-08 - Earliest claimed: 2014-07-22 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Gary Georgeson; Morteza Safai - Web page: https://patentgrep.com/patent/US10768128B2 ## CPC - G01N 25/72: Investigating presence of flaws - G01K 11/12: using changes in colour, translucency or reflectance - 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) - G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00) ## Abstract A method of monitoring a thermal protection system coupled to a structural component is provided. The thermal protection system includes a thermally insulative body and at least one layer of thermochromatic material applied thereon such that the at least one layer is positioned between the thermally insulative body and the structural component. The method includes determining a value of a thermochromatic property of the at least one layer of thermochromatic material, wherein the value of the thermochromatic property is responsive to an amount of heat applied to the at least one layer of thermochromatic material, comparing the value to a baseline value of the thermochromatic property, and determining degradation of the thermal protection system when the value of the thermochromatic property deviates from the baseline value. ## Claims ### Claim 1 A thermal protection system comprising: a thermally insulative body; and at least one layer of thermochromatic material applied to the thermally insulative body, wherein a value of a thermochromatic property of the at least one layer of thermochromatic material includes at least one of an intensity or a frequency of light emitted from the at least one layer of thermochromatic material when exposed to non-visible light and is responsive to an amount of heat applied to the at least one layer of thermochromatic material, wherein the value of the thermochromatic property irreversibly changes based on the amount of heat applied, and wherein the at least one layer of thermochromatic material is between the thermally insulative body and a substrate to be thermally protected. ### Claim 2 (depends on 1) The system in accordance with claim 1, wherein the at least one layer of thermochromatic material includes photoluminescent material configured to be activated by non-visible light. ### Claim 3 (depends on 1) The system in accordance with claim 1, wherein the at least one layer of thermochromatic material is configured such that the value of the thermochromatic property is modified to a first level when a temperature of the at least one layer is greater than a first predetermined threshold. ### Claim 4 (depends on 3) The system in accordance with claim 3, wherein the at least one layer of thermochromatic material is configured such that the value of the thermochromatic property remains at the first level when the temperature of the at least one layer reduces to below the first predetermined threshold. ### Claim 5 (depends on 3) The system in accordance with claim 3, wherein the at least one layer of thermochromatic material is configured such that the value of the thermochromatic property is permanently modified to a second level as the temperature of the at least one layer progressively increases above a second predetermined threshold. ### Claim 6 (depends on 1) The system in accordance with claim 1, wherein the at least one layer of thermochromatic material is configured such that the value of the thermochromatic property is substantially uniform across the at least one layer when the temperature of the at least one layer is less than a predetermined threshold. ### Claim 7 (depends on 1) The system in accordance with claim 1, wherein the at least one layer of thermochromatic material includes a plurality of portions each applied to a predetermined region of the thermally insulative body. ### Claim 8 (depends on 1) The system in accordance with claim 1, wherein the thermally insulative body is fabricated from a plurality of heat-resistant fibers. ### Claim 9 (depends on 1) The system in accordance with claim 1, wherein the thermal protection system is removably coupleable to the substrate. ### Claim 10 (depends on 1) The system in accordance with claim 1, wherein the thermally insulative body includes a first surface and a second surface, and the at least one layer of thermochromatic material is applied to the second surface, and wherein when the thermal protection system is exposed to a first amount of heat, the thermally insulative body is configured to inhibit heat transfer through the thermally insulative body from the first surface to the second surface so that only, a second amount of heat reaches the second surface and thereby the at least one layer of thermochromatic material. ### Claim 11 (depends on 1) The system in accordance with claim 1, wherein the thermally insulative body is a woven or nonwoven material formed of a plurality of heat-resistant fibers. ### Claim 12 (depends on 1) The system in accordance with claim 1, wherein the thermochromatic material is fabricated from one or more thermochromatic dyes responsive to temperatures above a predetermined threshold. ### Claim 13 (depends on 1) The system in accordance with claim 1, wherein the value of the thermochromatic property irreversibly changes a plurality of different levels as a temperature of the at least one layer of thermochromatic material progressively increases above a predetermined threshold so that an amount of heat that reaches the at least one layer of thermochromatic material is determinable based on which of the plurality of different levels the value has reached. ### Claim 14 (depends on 1) The system in accordance with claim 1, wherein the thermochromatic material includes photoluminescent material. ### Claim 15 (depends on 1) The system in accordance with claim 1, wherein the thermochromatic property is only visible to a human eye when activated by non-visible light.