De-lamination indicator

1. An indicator device for detecting a delamination of a composite material, including for detecting a delamination of a composite material of a wind turbine, or for detecting a delamination of a composite material of a wind turbine rotor blade, the indicator device comprising:

a first part arranged to fit into a hole in the composite material, wherein the hole spans at least a top layer and exposes a bottom layer of the composite material, and wherein when installed the first part is secured to the bottom layer,

a second part arranged to fit into the hole, wherein when installed the second part is secured to the top layer, and

an electric circuit that defines a loop in the hole,

wherein

the first part comprises at least a part of a lower part of the electric circuit,

the second part comprises at least a part of an upper part of the electric circuit, and

the lower part and the upper part are electrically connected to each other at a predetermined breaking point forming the electric circuit such that when the indicator device is in use in a composite material, if a delamination of the respective composite material occurs, the electric connection between the lower part and the upper part breaks at the predetermined breaking point, thus cutting the electric circuit.

2. The indicator device as set forth in claim 1 , wherein the lower part of the electric circuit is fixed to a bottom part of the first part.

3. The indicator device as set forth in claim 1 , wherein the upper part of the electric circuit is fixed inside the second part.

4. The indicator device as set forth in claim 1 , wherein the second part comprises an electrical connection of the electric circuit, wherein the electrical connection is adapted for being connected to an external monitoring system.

5. The indicator device as set forth in claim 1 , wherein the electric circuit acts a shunt.

6. The indicator device as set forth in claim 1 , wherein when the indicator device is in use in the composite material, if a displacement of two layers of the respective monitored composite material relative to each other occurs, the electric connection between the lower part and the upper part breaks at the predetermined breaking point, thus cutting the electric circuit.

7. The indicator device as set forth in claim 6 , wherein the displacement is caused by a shear stress in a parallel plane to a boundary plane between the respective two layers of the respective composite material.

8. The indicator device as set forth in claim 6 , wherein the displacement is caused due at least a partial separation of the respective two layers of the respective composite material.

9. The indicator device as set forth in claim 6 , wherein the electric connection between the lower part and the upper part breaks at the predetermined breaking point at a displacement of at least 1 mm.

10. A delamination detecting system for detecting a delamination of a composite material, including for detecting a delamination of a composite material of a wind turbine, or for detecting a delamination of a composite material of a wind turbine rotor blade, the delamination detecting system comprising:

the composite material, and

at least one indicator device according to claim 1 ,

wherein

the composite material comprises the bottom layer and the top layer,

a lower part of each indicator device is fixed in the bottom layer,

an upper part of each indicator device is fixed on a surface of the top layer, and wherein

the surface of the top layer is facing away from the bottom layer.

11. The delamination detecting system as set forth in claim 10 , the delamination detecting system comprising:

a plurality of said indicator devices, wherein the plurality of said indicator devices is arranged in the composite material in such a manner, that an area of delamination of the composite material may be localized.

12. A wind turbine rotor blade comprising a delamination detecting system of claim 10 .

13. A wind turbine comprising a wind turbine rotor blade of claim 12 .

14. A method for manufacturing a delamination detecting system, including a delamination detecting system for a wind turbine, or a delamination detecting system for a wind turbine rotor blade, the method comprising:

inserting at least one indicator device of claim 1 into a respective hole of the composite material,

fixedly arranging at least a part of a first part of each indicator device in a bottom layer of the composite material, and

fixedly arranging at least a part of a second part of each indicator device on a surface of a top layer of the composite material, wherein the surface is facing away from the bottom layer of the composite material.

15. The indicator device as set forth in claim 6 , wherein the electric connection between the lower part and the upper part breaks at the predetermined breaking point at a displacement of at least 0.1 mm.

16. The method for manufacturing a delamination detecting system of claim 14 , wherein fixedly arranging comprises gluing.

17. The indicator device as set forth in claim 1 , the second part further comprising a cap that secures to a top surface of the top layer when the first part is installed in the hole such that the cap moves with the top surface of the top layer.

18. The indicator device as set forth in claim 1 , wherein the indicator device is configured as a discrete insert that can be installed through the top layer.