Composite structure with optical fiber embedded in one of its surface layers and a process for its connection and repair

1. In a composite structure ( 11 ) for a primary structure of an aircraft, the composite structure comprising at least a surface layer ( 13 ), another layer ( 15 , 17 , 19 , 21 , 23 ) and an optical fiber ( 25 ) for structural monitoring purposes at least partly embedded in one of the layers, the improvements characterized in that:

a) the embedded part of the optical fiber ( 25 ) is integrated in a the surface layer ( 13 ) of the composite structure ( 11 ) to be susceptible to requiring repair; and

b) the composite structure ( 11 ) includes insulation means of at least areas of the embedded part of the optical fiber ( 25 ) with respect to the surface layer ( 13 ) said insulation means including a top separating film ( 31 ) and a bottom separating film ( 33 ), the top separating film ( 31 ) also comprising a laminar protective cover ( 27 ) arranged on the top of said top separating film ( 31 ).

2. A composite structure according to claim 1 , characterized in that said protective cover ( 27 ) is made of preimpregnated fiberglass fabric.

3. A composite structure according to claim 2 , characterized in that all of the optical fiber ( 25 ) is embedded in a surface layer ( 13 ) of the structure ( 11 ).

4. A composite structure according to claim 2 , characterized in that the part of the optical fiber ( 25 ) not embedded in the surface layer ( 13 ) of the structure ( 11 ) is embedded in the layer ( 15 ) adjacent to it or deeper.

5. A process of repairing the optical fiber ( 25 ) embedded in a composite structure ( 11 ) according to claim 3 , characterized in that it comprises the following steps:

a) Removing the protective cover ( 27 ) and the top separating film ( 31 ) from the optical fiber ( 25 ) area in need of repair;

b) Extracting the optical fiber ( 25 ) area in need of repair from the composite structure ( 11 );

c) Repairing the optical fiber ( 25 );

d) Relocating the repaired optical fiber ( 25 ) area in the composite structure ( 11 );

e) Providing a new protective cover ( 27 ) on the repaired optical fiber ( 25 ) area.

6. A process of repairing the optical fiber ( 25 ) embedded in a composite structure ( 11 ) according to claim 5 , characterized in that step d) includes the following additional steps:

d′) providing a new top separating film ( 31 ) on the repaired optical fiber ( 25 ) area;

d″) supplying adhesive ( 29 ) on the new separating film ( 31 ).

7. A process of repairing the optical fiber embedded in a composite structure according to claim 5 , characterized in that the repaired optical fiber ( 25 ) area connects ends ( 41 , 43 ) of optical fiber ( 25 ) embedded in the composite structure.

8. A process of repairing the optical fiber embedded in a composite structure according to claim 5 , characterized in that the repaired optical fiber ( 25 ) area connects one end ( 51 ) of optical fiber ( 25 ) embedded in the composite structure ( 11 ) with one end ( 53 ) of an optical fiber ( 55 ) located outside the composite structure ( 11 ).

9. A process of repairing the optical fiber ( 25 ) embedded in a composite structure ( 11 ) according to claim 4 , characterized in that it comprises the following steps:

a) Removing the protective cover ( 27 ) and the top separating film ( 31 ) from the optical fiber ( 25 ) area in need of repair;

b) Extracting the optical fiber ( 25 ) area in need of repair from the composite structure ( 11 );

c) Repairing the optical fiber ( 25 );

d) Relocating the repaired optical fiber ( 25 ) area in the composite structure ( 11 );

e) Providing a new protective cover ( 27 ) on the repaired optical fiber ( 25 ) area.

10. A process of repairing the optical fiber embedded in a composite structure according to claim 6 , characterized in that the repaired optical fiber ( 25 ) area connects ends ( 41 , 43 ) of optical fiber ( 25 ) embedded in the composite structure.

11. A process of repairing the optical fiber embedded in a composite structure according to claim 6 , characterized in that the repaired optical fiber ( 25 ) area connects one end ( 51 ) of optical fiber ( 25 ) embedded in the composite structure ( 11 ) with one end ( 53 ) of an optical fiber ( 55 ) located outside the composite structure ( 11 ).

12. A process of repairing the optical fiber ( 25 ) embedded in a composite structure ( 11 ) according to claim 11 , characterized in that step d) includes the following additional steps:

d′) providing a new top separating film ( 31 ) on the repaired optical fiber ( 25 ) area;

d″) supplying adhesive ( 29 ) on the new separating film ( 31 ).

13. A process of repairing the optical fiber embedded in a composite structure according to claim 9 , characterized in that the repaired optical fiber ( 25 ) area connects ends ( 41 , 43 ) of optical fiber ( 25 ) embedded in the composite structure.

14. A process of repairing the optical fiber embedded in a composite structure according to claim 12 , characterized in that the repaired optical fiber ( 25 ) area connects ends ( 41 , 43 ) of optical fiber ( 25 ) embedded in the composite structure.

15. A process of repairing the optical fiber embedded in a composite structure according to claim 9 , characterized in that the repaired optical fiber ( 25 ) area connects one end ( 51 ) of optical fiber ( 25 ) embedded in the composite structure ( 11 ) with one end ( 53 ) of an optical fiber ( 55 ) located outside the composite structure ( 11 ).

16. A process of repairing the optical fiber embedded in a composite structure according to claim 12 , characterized in that the repaired optical fiber ( 25 ) area connects one end ( 51 ) of optical fiber ( 25 ) embedded in the composite structure ( 11 ) with one end ( 53 ) of an optical fiber ( 55 ) located outside the composite structure ( 11 ).