Polymer matrix composite repair

Patent metadata

Field	Value
Publication number	US-11279100-B2
Application number	US-201916387107-A
Country	US
Kind code	B2
Filing date	Apr 17, 2019
Priority date	May 1, 2018
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

A procedure for repairing a polymer matrix composite component is provided. The procedure includes the steps of: providing a polymer matrix composite component having a site prepared for repair by removal of damaged or defective material; locating an uncured, polymer matrix composite repair patch at the site to re-build the component thereat; and curing the polymer matrix of the repair patch by heating the patch using eddy currents induced by one or more alternating current coils. The repair patch is without metallic additives, such that the repaired polymer matrix composite after the curing step is also without metallic additives in the vicinity of the repair patch.

First claim

The invention claimed is:

1. A procedure for repairing a polymer matrix composite component, the procedure comprising:
providing a polymer matrix composite component having a site prepared for repair by removal of damaged or defective material;
locating an uncured, polymer matrix composite repair patch at the site to re-build the component thereat; and
curing the polymer matrix of the repair patch by heating the patch using eddy currents induced by one or more alternating current coils, including a process of determining a desired maximum temperature of the patch and a desired penetration depth of the electromagnetic field produced by the one or more alternating current coils, and using said desired maximum temperature and said desired penetration depth to determine corresponding values of amp-turns and frequency which are then applied to the, or each, coil in the curing process;
wherein the repair patch is without metallic additives, such that the repaired polymer matrix composite after the curing step is also without metallic additives in the vicinity of the repair patch.

2. A procedure for repairing a polymer matrix composite component according to claim 1 , wherein the composite of the repair patch has sufficient intrinsic electrical conductivity without such additives to allow all the eddy currents used to heat the patch to flow only through the composite.

3. A procedure for repairing a polymer matrix composite component according to claim 1 , wherein pressure is applied to the repair patch during the curing.

4. A procedure for repairing a polymer matrix composite component according to claim 1 , wherein the polymer matrix composite of the repair patch is the same material as the polymer matrix composite of the component.

5. A procedure for repairing a polymer matrix composite component according to claim 1 , wherein the polymer matrix composite of the repair patch is a carbon fibre reinforced polymer matrix composite.

6. A procedure for repairing a polymer matrix composite component according to claim 1 , further comprising monitoring the patch temperature during the induction heating and adjusting amp-turns applied to the, or each, coil to attain a desired maximum temperature of the patch.

7. A procedure for repairing a polymer matrix composite component according to claim 1 , including a preliminary step of removing the damaged or defective material from the component to prepare the site.

8. A procedure for repairing a polymer matrix composite component according to claim 1 , in which a look-up table is used to relate the desired maximum temperature and said desired penetration depth to corresponding values of amp-turns and frequency.

9. A procedure for repairing a polymer matrix composite component according to claim 8 , in which the desired maximum temperature and said desired penetration depth are related to corresponding values of amp-turns and frequency by:
(i) providing geometric properties of the patch, geometric properties of the coil, electrical properties of the patch, and thermal properties of the patch;
(ii) determining a desired maximum temperature of the patch and a desired penetration depth of the electromagnetic field of the alternating current coil;
(iii) estimating values for the amp-turns and frequency of the alternating current to be applied to a coil:
(iv) using the provided geometric properties of the patch and the coil, the provided electrical properties, and the estimated values for the amp-turns and frequency to predict an eddy current density distribution in the patch and a corresponding penetration depth of the electromagnetic field produced by the coil,
(v) using the predicted eddy current density distribution, the provided geometric properties of the patch, and the provided thermal properties of the patch to predict the maximum temperature of the patch, and
(vi) repeating steps (iii) to (v) for different estimated values for the amp-turns and frequency of the alternating current until the predicted penetration depth and the predicted maximum temperature converge on the desired maximum temperature of the patch and a desired penetration depth of the electromagnetic field.

10. A method of determining values for amp-turns and frequency of an alternating current to be applied to an alternating current coil used for induction heating of a polymer matrix composite repair patch, the method comprising:
(i) providing geometric properties of the patch, geometric properties of the coil, electrical properties of the patch, and thermal properties of the patch;
(ii) determining a desired maximum temperature of the patch and a desired penetration depth of the electromagnetic field of the alternating current coil;
(iii) estimating values for the amp-turns and frequency of the alternating current to be applied to a coil:
(iv) using the provided geometric properties of the patch and the coil, the provided electrical properties, and the estimated values for the amp-turns and frequency to predict an eddy current density distribution in the patch and a corresponding penetration depth of the electromagnetic field produced by the coil,
(v) using the predicted eddy current density distribution, the provided geometric properties of the patch, and the provided thermal properties of the patch to predict the maximum temperature of the patch, and
(vi) repeating steps (iii) to (v) for different estimated values for the amp-turns and frequency of the alternating current until the predicted penetration depth and the predicted maximum temperature converge on the desired maximum temperature of the patch and a desired penetration depth of the electromagnetic field.

11. A method according to claim 10 , in which the estimated values for the amp-turns and frequency of the alternating current whose predicted penetration depth and the predicted maximum temperature match the desired maximum temperature of the patch and a desired penetration depth of the electromagnetic field are stored in a look-up table as a key-value pair.

12. A method according to claim 10 , in which steps (i) to (vi) are repeated for one or more of:
different geometric properties of the patch;
different geometric properties of the coil;
different electrical properties of the patch;
different thermal properties of the patch.

13. A non-transitory computer-readable medium encoded with one or more look-up tables constructed by the method of claim 11 .

Assignees

• Rolls Royce Plc

Inventors

• Lambourne Alexis
• Smith Alexander C
• Khan Jameel B

Classifications

• B29C35/0805

  using electromagnetic radiation · CPC title

• B29C2791/006

  Using vacuum · CPC title

• H05B6/14

  Tools, e.g. nozzles, rollers, calenders · CPC title

• B29C2035/0816

  using eddy currents · CPC title

• H05B6/44

  having more than one coil or coil segment · CPC title