Structural repair having optical witness and method of monitoring repair performance

Patent metadata

Field	Value
Publication number	US-9931827-B2
Application number	US-201514722149-A
Country	US
Kind code	B2
Filing date	May 27, 2015
Priority date	May 5, 2011
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A structural repair includes a tell-tale optical witness that allows the health of the repair to be visually monitored. The optical witness includes a stress sensitive fluorescent dye that shows changes in local strain/stress patterns when the repair is subjected to electromagnetic energy of a particular wavelength. The dyes fluoresce more or less strongly as a function of the local stress/strain.

First claim

What is claimed is:

1. A structural repair, that comprises:
a patch adapted to be adhesively bonded to a structure that requires a repair; and
a dye, incorporated directly into a resin within a polymer network in the patch, configured to indicate a current stress and load carrying ability of the patch, such that the dye comprises:
a sensitivity to both tensile and compressive stresses;
an end group that controls a combination of the dye with the polymer network; and
an aggregation sensitivity that comprises fluorescent molecules that, responsive to a change in an aggregation behavior of the dye, visually indicates at least one of partial failure or degradation in the repair such that each fluorescent molecule, in the fluorescent molecules, respectively comprises the end group configured to control an electron density of the fluorescent molecules and reactivity with components of the polymer network.

2. The structural repair of claim 1 , wherein:
the dye comprises a mechanochromatic dye that comprises an electromagnetic response.

3. The structural repair of claim 2 , further comprising the patch configured to bond to the structure, such that the fluorescent molecules comprise a molecular mobility configured to control, responsive to deformation of the structure, a proximity between dye molecules within the resin.

4. The structural repair of claim 2 , wherein the mechanochromatic dye comprises the fluorescent molecules, which comprise a fluorescence and positions in the resin, the fluorescent molecules configured via selection of their respective end group, such that responsive to a change in a localized stress in the repair, a change in molecules of the fluorescent molecules comprises a change in the fluorescence of the fluorescent molecule, such that responsive to electromagnetic energy on the patch, the change in the fluorescence becomes visible.

5. A system that monitors changes in a patch bonded to a structure, such that the system comprises:
a patch that comprises a number of fiber reinforced resin plies;
a resin ply cocured within the patch and configured to indicate a current stress and load carrying ability of the patch, such that the patch comprises a polymer network configured to attach over a portion of skin of the structure, such that the resin ply comprises:
fiber reinforced resin; and
an electromagnetic responsive dye incorporated directly into the resin that comprises:
a sensitivity to both tensile and compressive stresses;
an end group that controls a combination of the electromagnetic responsive dye with the polymer network; and
an aggregation sensitivity that comprises a fluorescent molecule that comprises:
a molecular mobility of the fluorescent molecule relative to the polymer network in the patch configured to control, responsive to deformation of the structure, a proximity between molecules of the electromagnetic responsive dye;
the end group configured to control, responsive to changes in stress in the patch, an electron density and reactivity, with components of the polymer network, of the fluorescent molecule; and

a device configured to:
record a baseline image that represents an optical behavior of the resin ply at a time that the resin ply and the patch are cocured, such that the baseline image comprises a first stress profile for the patch as indicated by the resin ply; and
produce an image that represents, responsive to a change in at least one of: a quenching, and an aggregation induced emission from the electromagnetic responsive dye, a new optical behavior of the resin ply that represents a new stress profile in the resin ply, such that the new stress profile in the resin ply comprises arises from at least one of:
a delamination in the number of fiber reinforced resin plies; and
a disbanding of the patch; and

subject the resin ply to electromagnetic energy of a preselected wavelength;
record the optical behavior of the resin ply;
collect photoluminescent quantum yield and fluorescence emission spectra from the resin ply;
compare the first stress profile and the new stress profile.

6. The system of claim 5 , further comprising the device comprising a photoluminescent device.

7. The system of claim 5 , further comprising the device configured to:
mark, responsive to the optical behavior comprising an indication that indicates a change, responsive to a delamination between the number of fiber reinforced resin plies of the patch, in the stress in the patch, an area of the structure containing the patch; and
perform, based upon a traditional nondestructive evaluation technique that comprises one of: bond testing, and ultrasonic inspection, further non-destructive evaluation of the patch.

8. A system configured to repair an area of an aircraft component, such that the system comprises:
a patch configured to bond to the aircraft component and occupy a portion of the aircraft component over the area, such that the patch comprises a polymer network and a number of composite plies that comprise fiber reinforced resin;
a composite ply, in the number of composite plies, that comprises:
an electromagnetic responsive dye incorporated directly into the fiber reinforced resin configured to indicate a current stress and a current load carrying ability in the patch, such that the electromagnetic responsive dye comprises:
a sensitivity to both tensile and compressive stresses;
an end group that controls a combination of the electromagnetic responsive dye with the polymer network; and
an aggregation sensitivity that comprises a fluorescent molecule that, responsive to a change in an aggregation behavior of the electromagnetic responsive dye, presents an optical behavior that varies in response to changes in the current stress in the patch, that comprises a customized end group configured to control an electron density of the fluorescent molecule and reactivity with components of the polymer network and the electromagnetic responsive dye comprises a functionalized stilbene dye that comprises tert-butyl dimethyl silane end groups;
a photoluminescent device configured to:
record a baseline image that represents the optical behavior of the patch at a time that the patch bonds to the aircraft component, such that the baseline image comprises a first stress profile for the patch;
record subsequent images of the patch that represent the optical behavior of the patch;
obtain a new image of the patch, such that the new image represents the optical behavior of the patch and comprises a new stress profile, based upon a delamination between the number of composite plies, for the patch;
compare the new image to the baseline image and the first stress profile to the new stress profile; and
identify any abnormalities in the new stress profile, such that the first stress profile and the new stress profile each comprises a mapping of a fluorescence, unique to the respective stress profile of the patch, to areas that exhibit the fluorescence.

9. The system of claim 8 , further comprising the photoluminescent device configured to record each new image via being configured to:
subject the patch to electromagnetic energy of a preselected wavelength; and
collect photoluminescent quantum yield and fluorescence emission spectra from the patch.

10. The system of claim 8 , further comprising the photoluminescent device configured to: mark an area of the aircraft component containing the patch when comparison of the new image to the baseline image indicates a change in the current stress in the patch, and perform further non-destructive evaluation of the patch using a traditional nondestructive evaluation technique comprising one of bond testing and ultrasonic inspection.

Assignees

• Boeing Co

Inventors

• Georgeson Gary E
• Griess Kenneth Harlan
• Keller Russell Lee
• Westerman Everett A

Classifications

• B29C73/10

  using patches sealing on the surface of the article (B29C73/14 takes precedence) · CPC title

• G01L5/00

  Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes · CPC title

• Y10T428/28

  Web or sheet containing structurally defined element or component and having an adhesive outermost layer · CPC title

• B32B2605/18

  Aircraft · CPC title

• B23P6/00

  Restoring or reconditioning objects (straightening or restoring form of sheet metal, metal rods, metal tubes, metal profiles, or specific articles made therefrom B21D1/00, B21D3/00; repairing defective or damaged objects by casting techniques B22D19/10) · CPC title