Reinforcing structure for a wind turbine blade
A reinforcing structure for a wind turbine blade A reinforcing structure for a wind turbine blade ( 12 ) is described. The reinforcing structure comprises one or more pultruded strips ( 42 C) having spanwise grooves ( 54 ). The grooves ( 54 ) impart transverse flexibility to the strips ( 42 C), allowing the strips ( 42 C) to conform to the curvature of a wind turbine blade mould ( 44 ). An associated method of making a reinforcing structure for a wind turbine blade ( 12 ) is described. The method comprises providing an elongate mould ( 44 ) extending in a longitudinal direction and defining a mould surface at least part of which is concave-curved in transverse cross section. One or more pultruded strips ( 42 C) with spanwise grooves ( 54 ) are arranged in the mould ( 44 ) to form the reinforcing structure. The pultruded strip(s) are bent along the grooves ( 54 ) so that they substantially conform to the transverse curvature of the mould surface. In preferred embodiments the reinforcing structure is a spar cap ( 36 ).
1. A method of making a reinforcing structure for a wind turbine blade through a moulding process, the method comprising:
providing an elongate mould extending in a longitudinal direction and defining a mould surface at least part of which is concave-curved in transverse cross section;
arranging one or more pultruded strips in the mould to form the reinforcing structure, the one or more pultruded strips having one or more longitudinally-extending grooves; and
bending and/or cracking the one or more pultruded strips along the one or more grooves such that the one or more pultruded strips substantially conform to the transverse curvature of the mould surface to define a plurality of planar strip portions, each of the plurality of planar strip portions having a lower surface that is closest to the mould surface, wherein the lower surface remains flat relative to the transverse curvature of the mould surface upon completion of the moulding process.
2. The method of claim 1 , wherein the reinforcing structure is a spar cap.
3. The method of claim 1 , comprising stacking a plurality of the pultruded strips in the mould to form a stack in which each strip is flat in transverse cross section; and bending and/or cracking the stack of strips in the mould along at least one groove of at least one strip such that the stack of strips conforms to the transverse curvature of the mould surface.
4. The method of claim 1 , further comprising:
at least partially covering the one or more pultruded strips with a vacuum bagging film to form a sealed region in the mould enclosing the one or more pultruded strips; and
removing air from the sealed region such that the vacuum bagging film exerts a force on the one or more pultruded strips and causes the one or more pultruded strips to bend and/or crack along the one or more grooves.
5. The method of claim 1 , wherein the mould is a wind turbine blade mould, and the method comprises forming the reinforcing structure in the mould integrally with a shell of the wind turbine blade.
6. The method of claim 1 , wherein the one or more pultruded strips are made from fibre-reinforced polymeric material.
7. A method of making a reinforcing structure for a wind turbine blade through a moulding process, the method comprising:
providing an elongate mould extending in a longitudinal direction and defining a mould surface at least part of which is concave-curved in transverse cross section;
arranging one or more pultruded strips in the mould to form the reinforcing structure, the one or more pultruded strips having one or more longitudinally-extending grooves; and
cracking the one or more pultruded strips along the one or more grooves such that the one or more pultruded strips substantially conform to the transverse curvature of the mould surface to define a plurality of planar strip portions upon completion of the moulding process.