Sub-surface patterning for diffraction-based strain measurement and damage detection in structures

Patent metadata

Field	Value
Publication number	US-11243071-B2
Application number	US-202016780601-A
Country	US
Kind code	B2
Filing date	Feb 3, 2020
Priority date	Feb 3, 2020
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

Systems and methods for assessing strain in structural components are disclosed. Structural components may have geometric patterns of diffraction cavities within the structural component, with the diffraction cavities in the geometric pattern each having a cavity width and being spaced from each other by a cavity spacing distance. The method may include projecting beams of electromagnetic (EM) energy through the structural component to the geometric pattern of diffraction cavities to create diffracted beams of EM energy that are reflected from or transmitted through the geometric pattern of diffraction cavities and have diffracted wavelengths indicating changes in the cavity spacing distances due to strain caused when the structural component is exposed to environmental conditions, detecting the diffracted wavelength of the diffracted beams, and correlating the diffracted wavelengths of the diffracted beams to the strain in the structural components.

First claim

What is claimed is:

1. A structural component comprising:
a first outer surface;
a second outer surface; and
a first geometric pattern of diffraction cavities formed by first surfaces within the structural component, the first geometric pattern of diffraction cavities having a first set of diffraction cavities spaced from each other by a first cavity spacing distance, wherein the diffraction cavities are unfilled spaces within the structural component, and wherein a first projected beam of electromagnetic (EM) energy having a first wavelength corresponding to the first cavity spacing distance is diffracted when the first projected beam of EM energy hits the first set of diffraction cavities and creates a first diffracted beam of diffracted EM energy having a first diffracted wavelength indicating changes in the first cavity spacing distance due to strain caused when the structural component is exposed to an environmental condition, wherein the first geometric pattern of diffraction cavities is a two-dimensional geometric pattern, wherein each of the diffraction cavities of the first set of diffraction cavities is an elongated cavity that defines the same geometric shape, wherein the geometric shapes defined by the diffraction cavities are arranged concentrically about a center of the two-dimensional geometric pattern, and wherein an area of the geometric shape defined by each of the diffraction cavities increases as a distance from the center of the two-dimensional geometric pattern to the diffraction cavities increases.

2. The structural component according to claim 1 , wherein the first geometric pattern of diffraction cavities reflects the first projected beam of EM energy passing through the structural component to transmit the first diffracted beam of diffracted EM energy through the first outer surface.

3. The structural component according to claim 1 , when the first projected beam of EM energy passes through the first outer surface to the first geometric pattern of diffraction cavities, and the first diffracted beam of diffracted EM energy passes through the second outer surface and out of the structural component.

4. The structural component according to claim 1 , wherein the first cavity spacing distance between adjacent diffraction cavities of the first geometric pattern increases as the first geometric pattern extends outward from a central point.

5. A structural component comprising:
a first outer surface;
a second outer surface; and
a first geometric pattern of diffraction cavities formed by first surfaces within the structural component, the first geometric pattern of diffraction cavities having a first set of diffraction cavities spaced from each other by a first cavity spacing distance, wherein the diffraction cavities are unfilled spaces within the structural component, and wherein a first projected beam of electromagnetic (EM) energy having a first wavelength corresponding to the first cavity spacing distance is diffracted when the first projected beam of EM energy hits the first set of diffraction cavities and creates a first diffracted beam of diffracted EM energy having a first diffracted wavelength indicating changes in the first cavity spacing distance due to strain caused when the structural component is exposed to an environmental condition; and
a second geometric pattern of diffraction cavities formed by second surfaces within the structural component between the first geometric pattern of diffraction cavities and the second outer surface, the second geometric pattern of diffraction cavities having a second set of diffraction cavities spaced from each other by a second cavity spacing distance that is different than the first cavity spacing distance, wherein a second projected beam of EM energy having a second wavelength corresponding to the second cavity spacing distance is diffracted when the second projected beam of EM energy hits the second set of diffraction cavities and creates a second diffracted beam of diffracted EM energy having a second diffracted wavelength indicating changes in the second cavity spacing distance due to the strain caused when the structural component is exposed to the environmental condition.

6. The structural component according to claim 5 , wherein the second cavity spacing distance is greater than the first cavity spacing distance and the second wavelength is greater than the first wavelength so that the second projected beam of EM energy passes through the first geometric pattern of diffraction cavities without being diffracted.

7. A structural component comprising:
a first outer surface;
a second outer surface; and
a first geometric pattern of diffraction cavities formed by first surfaces within the structural component, the first geometric pattern of diffraction cavities having a first set of diffraction cavities spaced from each other by a first cavity spacing distance, wherein the diffraction cavities are unfilled spaces within the structural component, and wherein a first projected beam of electromagnetic (EM) energy having a first wavelength corresponding to the first cavity spacing distance is diffracted when the first projected beam of EM energy hits the first set of diffraction cavities and creates a first diffracted beam of diffracted EM energy having a first diffracted wavelength indicating changes in the first cavity spacing distance due to strain caused when the structural component is exposed to an environmental condition, wherein the first geometric pattern of diffraction cavities comprises a two-dimensional geometric pattern having a second set of diffraction cavities each having a second cavity spacing distance and spaced in a second direction that is not parallel to a first direction in which the first set of diffraction cavities is spaced.

8. The structural component according to claim 7 , wherein the second cavity spacing distance is not equal to the first cavity spacing distance, wherein a second projected beam of EM energy having a second wavelength corresponding to the second cavity spacing distance is diffracted when the second projected beam of EM energy hits the second set of diffraction cavities and creates a second diffracted beam of diffracted EM energy having a second diffracted wavelength indicating changes in the second cavity spacing distance due to the strain caused when the structural component is exposed to the environmental condition.

9. A structural component comprising:
a first outer surface;
a second outer surface; and
a first geometric pattern of diffraction cavities formed by first surfaces within the structural component, the first geometric pattern of diffraction cavities having a first set of diffraction cavities spaced from each other by a first cavity spacing distance, wherein the diffraction cavities are unfilled spaces within the structural component, and wherein a first projected beam of electromagnetic (EM) energy having a first wavelength corresponding to the first cavity spacing distance is diffracted when the first projected beam of EM energy hits the first set of diffraction cavities and creates a first diffracted beam of diffracted EM energy having a first diffracted wavelength indicating changes in the first cavity spacing distance due to strain caused when the structural component is exposed to an environmental condition, wherein the first geometric pattern of diffraction cavities has a second set of diffraction cavities each having a second cavity spacing distance, wherein a second projected beam of EM energy having a second wavelength corresponding to the second cavity spacing distance is diffracted when the second projected beam of EM energy hits the second set of diffraction cavities and creates a second diffracted beam of dif

Assignees

• Boeing Co

Inventors

• Georgeson Gary E
• Griess Kenneth H
• Keller Russell L

Classifications

• G01B11/165 Primary

  by means of a grating deformed by the object · CPC title

• G01B11/167

  by projecting a pattern on the object · CPC title

• G01B7/16 Primary

  for measuring the deformation in a solid, e.g. by resistance strain gauge · CPC title

• G01B11/16

  for measuring the deformation in a solid, e.g. optical strain gauge · CPC title

• G01B15/06

  for measuring the deformation in a solid · CPC title