SURROGATE PATCH FOR COMPOSITE REPAIR PROCESS

• US 20110132523A1
• Filed: 12/08/2009
• Published: 06/09/2011
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Evens, Michael W., Watson, Megan N., Vargas, Mary H.
• Granted Patent: US 8,545,650 B2
• Time in Patent Office: Days
• US Class Current: 156/94
• CPC Class Codes: B29C 73/10 using patches sealing on the surface of the article B29C73/14 takes precedence
• CPC Class Codes: B29C 73/12 Apparatus therefor, e.g. for applying B29C73/30 takes precedence
• CPC Class Codes: B29C 73/163 Sealing compositions or agents, e.g. combined with propellant agents
• CPC Class Codes: B29C 73/34 for local heating
• CPC Class Codes: B32B 43/00 Operations specially adapted for layered products and not otherwise provided for, e.g. repairing; Apparatus therefor
• CPC Class Codes: G01K 13/00 Thermometers specially adapted for specific purposes
• CPC Class Codes: G01N 27/00 Investigating or analysing materials by the use of electric, electrochemical, or magnetic means G01N3/00 – G01N25/00 take precedence; measurement or testing of electric or magnetic variables or of electric or magnetic properties of materials G01R
• CPC Class Codes: G01N 33/00 Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00

Abstract

A surrogate patch assembly for a rework area of a structure comprises a surrogate patch body which may be formed of a material for drawing moisture from the rework area. The patch assembly may include a sensor mounted to the surrogate patch body. The sensor may comprise a thermal sensor for sensing the temperature of the rework area and the surrogate patch body. The sensor may comprise a moisture sensor for sensing moisture drawn into the surrogate patch body.

Claims

1. A surrogate patch assembly for a rework area of a structure, comprising:

a surrogate patch body formed of a material for drawing moisture from the rework area; and

at least one sensor mounted to the surrogate patch body and being configured as one of the following;

a thermal sensor for sensing a temperature of at least one of the rework area and the surrogate patch body; and

a moisture sensor for sensing moisture in the surrogate patch body.

2. The surrogate patch assembly of claim 1 wherein:

the moisture sensor comprises at least one of a moisture detection strip and an electrochemical impedance spectroscopy (EIS) sensor.

3. The surrogate patch assembly of claim 1 wherein:

the surrogate patch body includes a top surface having a plurality of moisture sensors mounted thereon.

4. The surrogate patch assembly of claim 1 wherein:

the surrogate patch body has top and bottom surfaces, at least one of the sensors being mounted in one of the following locations;

the top surface, the bottom surface, embedded within the surrogate patch body between the top and bottom surfaces.

5. The surrogate patch assembly of claim 1 wherein:

the surrogate patch body comprises a plurality of layers;

at least one of the sensors being interposed between a pair of the layers.

6. The surrogate patch assembly of claim 1 wherein:

the material comprises one of natural and synthetic material including at least one of the following;

wool, cotton, silk, linen, polyester, nylon, acrylic.

7. The surrogate patch assembly of claim 6 wherein:

the material comprises felt.

8. The surrogate patch assembly of claim 1 wherein:

the surrogate patch body is conformable in three-dimensions such that the surrogate patch body is conformable to the rework area.

9. The surrogate patch assembly of claim 1 wherein:

the rework area is configured to receive a patch;

the surrogate patch body having a specific heat capacity and a thermal conductivity that is substantially equivalent to at least one of the specific heat capacity and thermal conductivity of the patch.

10. The surrogate patch assembly of claim 9 wherein:

the surrogate patch body is formed of material having a thermal conductivity in the range of from approximately 0.01 W/mK to approximately 1.0 W/mK.

11. The surrogate patch assembly of claim 9 wherein:

the surrogate patch body is formed of material having a specific heat capacity in the range of from approximately 600 J/(kgK) to approximately 1100 J/(kgK).

12. A surrogate patch assembly for a rework area of a composite structure, comprising:

a surrogate patch body having top and bottom surfaces and defining a substantially uniform thickness, the surrogate patch body being formed of felt for drawing moisture from the rework area, the felt having a thermal conductivity of approximately 0.01 to 1.0 W/mK and a specific heat capacity of approximately 600 to 1100 J/(kgK);

a plurality of thermal sensors mounted to the surrogate patch body for sensing a temperature of the rework area and the surrogate patch body, at least one of the thermal sensors being embedded within the surrogate patch body between the top and bottom surfaces; and

a plurality of moisture sensors mounted to the surrogate patch body on the top surface for sensing moisture absorbed from the rework area.

13. A surrogate patch system for repairing a structure with a patch receivable within a rework area, the system comprising:

a surrogate patch body formed of non-composite material having thermal properties substantially similar to thermal properties of the patch, the thermal properties comprising at least one of specific heat capacity and thermal conductivity;

at least one thermal sensor mounted on the surrogate patch body for sensing a temperature of the surrogate patch body; and

at least one thermal sensor mounted on the rework area for sensing a temperature of the rework area.

14. The surrogate patch system of claim 13 wherein the surrogate patch body has at least one of the following thermal properties:

a thermal conductivity in the range of from approximately 0.01 W/mK to approximately 1.0 W/mK;

a specific heat capacity in the range of from approximately 600 J/(kgK) to approximately 1100 J/(kgK).

15. The surrogate patch system of claim 13 wherein:

the surrogate patch body is formed of a material for drawing moisture from the rework area.

16. The surrogate patch system of claim 13 wherein:

the surrogate patch body includes a plurality of moisture sensors mounted thereon.

17. The surrogate patch system of claim 16 wherein:

the surrogate patch body comprises a plurality of layers;

at least one of the thermal sensor and moisture sensors being interposed between a pair of the layers.

18. The surrogate patch system of 13 wherein the structure includes upper and lower surfaces and having at least one heat sink mounted on the lower surface adjacent to the rework area, the system further comprising:

at least one thermal sensor mounted on the upper surface opposite the location of the heat sink on the bottom surface.

19. A method of repairing a composite structure having upper and lower surfaces, comprising the steps of:

forming a surrogate patch body of material for drawing moisture from a rework area of the composite structure;

mounting at least one sensor on the surrogate patch body;

installing the surrogate patch body in the rework area; and

performing at least one of the following;

conducting a thermal survey of the rework area;

removing moisture from the rework area.

20. The method of claim 19 further comprising the step of:

mounting at least one thermal sensor in the rework area.

21. The method of claim 19 further comprising at least one of the following steps:

forming the surrogate patch body to have a thermal conductivity in the range of from approximately 0.01 W/mK to approximately 1.0 W/mK;

forming the surrogate patch body to have a specific heat capacity in the range of from approximately 600 J/(kgK) to approximately 1100 J/(kgK).

22. The method of claim 19 further comprising the step of:

forming the surrogate patch body from felt.

23. The method of claim 19 wherein the step of mounting at least one sensor in the rework area comprises:

mounting at least one thermal sensor on the surrogate patch body for sensing a temperature of at least one of the rework area and the surrogate patch body; and

mounting at least one moisture sensor on the surrogate patch body for sensing moisture drawn from the rework area;

24. The method of claim 19 further comprising the steps of:

vacuum bagging the surrogate patch body to the upper surface with a bagging film; and

drawing a vacuum on the bagging film.

25. The method of claim 19 further comprising the step of:

heating the rework area.

26. A method of repairing a composite structure comprised of a plurality of plies, the structure having upper and lower surfaces, the upper surface including a rework area for receiving a patch, the lower surface having at least one heat sink disposed thereon, the method comprising the steps of:

forming a surrogate patch body of material for drawing moisture from the rework area, the surrogate patch body having a specific heat capacity and a thermal conductivity substantially similar to the specific heat capacity and thermal conductivity of the patch;

mounting a thermal sensor on the surrogate patch body for sensing a temperature of at least one of the rework area and the surrogate patch body;

mounting a moisture sensor on the surrogate patch body for sensing moisture drawn from the rework area;

mounting a thermal sensor on the upper surface of the composite structure opposite a location of the heat sink on the lower surface;

mounting a thermal sensor in at least one of a bottom center and a scarf of the rework area;

covering the rework area with a porous parting film;

installing the surrogate patch body in the rework area over the parting film;

covering the surrogate patch body with a breather layer;

installing a heating blanket over the breather layer;

installing a breather layer over the heating blanket;

vacuum bagging the surrogate patch body and heating blanket with a bagging film;

heating the rework area;

drawing a vacuum on the bagging film; and

performing at least one of the following;

conducting a thermal survey of the rework area;

removing moisture from the rework area.