Method of manufacturing a composite laminate structure of a wind turbine blade part and related wind turbine blade part

1. A method of manufacturing a composite laminate structure of a wind turbine blade part by means of resin transfer moulding, where fibre-reinforcement material is impregnated with liquid resin in a mould cavity, wherein the mould cavity comprises a rigid mould part having a mould surface defining a surface of the wind turbine blade part, the method comprising the following steps:

a. alternately stacking on the rigid mould part:

i. a number of fibre-reinforcement layers comprising electrically conductive fibres, and

ii. a flow strip layer in form of a layer of flow strips, each having a strip width, and which are arranged so as to form spacings having a spacing width between two juxtaposed strips, wherein the strip width is larger than the spacing width,

b. sealing a second mould part against the rigid mould part in order to form the mould cavity,

c. optionally evacuating the mould cavity,

d. supplying a resin to the mould cavity, and

e. curing or hardening the resin in order to form the composite laminate structure,

wherein the fibre-reinforcement layers and the layer of flow strips are arranged such that at least a number of electrically conductive fibres on a first fibre-reinforcement layer on a first side of one of the flow strip layers have sufficient contact with a number of electrically conductive fibres on a second fibre-reinforcement layer on a second side of the flow strip layer through the spacings to conduct a current across a thickness of the composite laminate structure.

2. The method according to claim 1 , wherein the composite laminate structure is a load-carrying structure of the wind turbine blade, the composite laminate structure having a longitudinal direction, and wherein the flow strips are aligned in a desired flow direction and fibres of the fibre-reinforcement layers are aligned substantially in the longitudinal direction.

3. The method according to claim 2 , wherein the load-carrying structure is a spar cap integrated in a shell of the wind turbine blade.

4. The method according to claim 1 , wherein the flow strips are secured to one of the fibre-reinforcement layers.

5. The method according to claim 1 , wherein the layers of flow strips are arranged so that flow strips of a first flow strip layer overlap flow strips of a second flow strip layer.

6. The method according to claim 1 , wherein at least a number of flow strips are made of a bi-axial mesh.

7. The method according to claim 1 , wherein at least a number of flow strips are made of an open-meshed fabric.

8. The method according to claim 1 , wherein the fibre-reinforcement material is a hybrid material comprising glass fibres and carbon fibres, and wherein a spacing between carbon fibres is smaller than the spacing width.

9. The method according to claim 1 , wherein the number of fibre-reinforcement layers of step a.i. is between 3 and 9.

10. The method according to claim 1 , wherein said resin transfer moulding comprises vacuum-assisted resin transfer moulding.

11. The method according to claim 1 , wherein the electrically conductive fibres comprise carbon fibres.

12. A wind turbine blade part comprising a composite laminate structure, wherein the composite laminate structure comprises alternately stacked layers of:

i. a number of fibre-reinforcement layers comprising electrically conductive fibres, and

ii. a flow strip layer in form of a layer of flow strips having a strip width and which are arranged so as to form spacings having a spacing width between two juxtaposed strips, wherein the strip width is larger than the spacing width, and wherein

the alternately stacked layers are embedded in a polymer matrix material, wherein the fibre-reinforcement layers and the layer of flow strips are arranged such that at least a number of electrically conductive fibres on a first fibre-reinforcement layer on a first side of one of the flow strip layers have sufficient contact with a number of electrically conductive fibres on a second fibre-reinforcement layer on a second side of the flow strip layer through the spacings to conduct a current across a thickness of the composite laminate structure.

13. A wind turbine comprising the wind turbine blade part according to claim 12 .

14. The wind turbine blade part according to claim 12 , wherein the electrically conductive fibres comprise carbon fibres.

15. A method of manufacturing a composite laminate structure of a wind turbine blade part by means of resin transfer moulding, where fibre-reinforcement material is impregnated with liquid resin in a mould cavity, wherein the mould cavity comprises a rigid mould part having a mould surface defining a surface of the wind turbine blade part, the method comprising the following steps:

a. alternately stacking on the rigid mould part:

i. a number of fibre-reinforcement layers comprising electrically conductive fibres, and

ii. a flow strip layer in form of a layer of flow strips, each having a strip width, and which are arranged so as to form spacings having a spacing width between two juxtaposed strips, wherein the strip width is larger than the spacing width, wherein at least a number of flow strips are made of a material selected from the group consisting of a bi-axial mesh and an open-meshed fabric,

b. sealing a second mould part against the rigid mould part in order to form the mould cavity,

c. optionally evacuating the mould cavity,

d. supplying a resin to the mould cavity, and

e. curing or hardening the resin in order to form the composite laminate structure,

wherein the fibre-reinforcement layers and the layer of flow strips are arranged such that at least a number of electrically conductive fibres on a first fibre-reinforcement layer on a first side of one of the flow strip layers have sufficient contact with a number of electrically conductive fibres on a second fibre-reinforcement layer on a second side of the flow strip layer through the spacings to conduct a current across a thickness of the composite laminate structure.