Optimized spar cap structure for wind turbine blade
The present disclosure relates to a spar cap ( 10 ) for a wind turbine blade ( 1000 ) comprising: a plurality of spar cap layers ( 20 ) and a first interlayer ( 30 ) arranged between the first spar cap layer ( 20 a ) and the second spar cap layer ( 20 b ) and comprising: a number of first interlayer areas ( 31 ), including a first primary interlayer area ( 31 a ), comprising a first number of interlayer sheets ( 33 ) comprising a first plurality of fibres ( 35 ); and a number of second interlayer areas ( 32 ), including a second primary interlayer area ( 32 a ), comprising a second number of interlayer sheets ( 34 ) comprising a second plurality of fibres ( 36 ), wherein the first number of interlayer sheets ( 33 ) is of a different characteristic than the second number of interlayer sheets ( 34 ).
1. A spar cap ( 10 ) for a wind turbine blade ( 1000 ) comprising:
a plurality of spar cap layers ( 20 ) each including:
a first spar cap layer ( 20 a ) comprising a first number of pre-cured fibre-reinforced elements ( 21 ), including a first primary pre-cured fibre-reinforced element ( 21 a ); and
a second spar cap layer ( 20 b ) comprising a second number of pre-cured fibre-reinforced elements ( 22 ), including a second primary pre-cured fibre-reinforced element ( 22 a ),
wherein each of the first and second number of pre-cured fibre reinforced elements ( 21 , 22 ) has a length (L), a width (W) and a thickness (T),
wherein a first interlayer ( 30 ) is arranged between the first spar cap layer ( 20 a ) and the second spar cap layer ( 20 b ), the first interlayer ( 30 ) comprising:
a number of first interlayer areas ( 31 ), including a first primary interlayer area ( 31 a ), comprising a first number of interlayer sheets ( 33 ) comprising a first plurality of fibres ( 35 ); and
a number of second interlayer areas ( 32 ), including a second primary interlayer area ( 32 a ), comprising a second number of interlayer sheets ( 34 ) comprising a second plurality of fibres ( 36 );
wherein the first number of interlayer sheets ( 33 ) is of a different characteristic than the second number of interlayer sheets ( 34 ), and
wherein the first spar cap layer ( 20 a ) further comprises a first secondary pre-cured fibre-reinforced element ( 21 b ) arranged adjacent to the first primary pre-cured fibre reinforced element ( 21 a ), such that a first side of the first primary pre-cured fibre-reinforced element ( 21 a ) is defined by the thickness and length of the first primary pre-cured fibre-reinforced element ( 21 a ), and is further positioned adjacent to a second side of the first secondary pre-cured fibre-reinforced element ( 21 b ), which is defined by the thickness and length of the first secondary pre-cured fibre-reinforced element ( 21 b ).
2. The spar cap according to claim 1 , wherein the different characteristic is fibre type and/or fibre density and/or fibre ratio.
3. The spar cap according to claim 1 , wherein the first spar cap layer ( 20 a ), the second spar cap layer ( 20 b ) and the first interlayer ( 30 ) each have a length (La, Lb, Lc), a width (Wa, Wb, Wc) and a thickness (Ta, Tb, Tc), wherein the width (Wc) and length (Lc) of the first interlayer are the same as the width (Wa, Wb) and length (La, Lb), respectively, of the first and/or second spar cap layer.
4. The spar cap according to claim 1 , wherein the first spar cap layer ( 20 a ), the second spar cap layer ( 20 b ) and the first interlayer ( 30 ) each have a first surface area ( 20 aa , 20 ba , 30 a ) and an opposite second surface area ( 20 ab , 20 bb , 30 b ), wherein the first surface area ( 20 aa , 20 ba , 30 a ) of the first spar cap layer ( 20 a ), the second spar cap layer ( 20 b ) and the first interlayer ( 30 ) is defined by the width and length of the first spar cap layer ( 20 a ), the second spar cap layer ( 20 b ) or the first interlayer ( 30 ), respectively, and wherein the first surface area ( 30 a ) of the first interlayer ( 30 ) is in contact with the second surface area ( 20 ab ) of the first spar cap layer ( 20 a ) and the second surface area ( 30 b ) of the first interlayer ( 30 ) is in contact with the first surface area ( 20 ba ) of the second spar cap layer ( 20 b ).
5. The spar cap according to claim 1 , wherein the first primary interlayer area ( 31 a ) extends along a first part of a length of the first interlayer ( 30 ) and wherein the second primary interlayer area ( 32 a ) extends along a second part of the length of the first interlayer ( 30 ).
6. The spar cap according to claim 1 , wherein the first primary interlayer area ( 31 a ) extends along a first part of a width of the first interlayer ( 30 ) and wherein the second primary interlayer area ( 32 a ) extends along a second part of the width of the first interlayer ( 30 ).
7. The spar cap according to claim 1 , wherein the second primary interlayer area ( 32 a ) is positioned adjacent to the first primary interlayer area ( 31 a ).
8. The spar cap according to claim 1 , wherein the first primary interlayer area ( 31 a ) forms at least part of a perimeter of the first interlayer ( 30 ).
9. The spar cap according to claim 1 , wherein the first interlayer ( 30 ) comprises a plurality of second interlayer areas ( 32 ), including the second primary interlayer area ( 32 a ).
10. The spar cap according to claim 9 , wherein the number of first interlayer areas ( 31 ) and the plurality of second interlayer areas ( 32 ) each extends along part of a length of the first interlayer ( 30 ), and wherein the number of first interlayer areas ( 31 ) and the plurality of second interlayer areas ( 32 ) are alternating along the length of the first interlayer ( 30 ).
11. The spar cap according to claim 9 , wherein the first plurality of interlayer areas ( 31 ) and the second plurality of interlayer areas ( 32 ) each extends along part of a width of the first interlayer ( 30 ), and wherein the first plurality of interlayer areas ( 31 ) and the second plurality of interlayer areas ( 32 ) are alternating along the width of the first interlayer ( 30 ).
12. The spar cap according to claim 1 , wherein the first number of interlayer sheets and the second number of interlayer sheets are arranged adjacent to each other such that adjacent edges of the interlayer sheets are contacted with each other or wherein the first number of interlayer sheets and the second number of interlayer sheets overlap each other in areas where the first and second number of interlayer sheets meet.
13. The spar cap according to claim 1 , wherein the first plurality of fibres ( 35 ) comprises polymeric filaments.
14. The spar cap according to claim 1 , wherein the second plurality of fibres ( 36 ) comprises glass fibres and/or carbon fibres.
15. The spar cap according to claim 1 , wherein the first and/or second number of interlayer sheets ( 33 , 34 ) are veils comprising randomly oriented fibres.
16. The spar cap according to claim 1 , wherein the first and/or second number of interlayer sheets ( 33 , 34 ) are nets, comprising woven fibres.
17. The spar cap according to claim 1 , wherein the first number of interlayer sheets ( 33 ) are polyester veils and the second number of interlayer sheets ( 34 ) are bidirectional glass-fibre fabrics.
18. The spar cap according to claim 1 , wherein each of the first and second number of pre-cured fibre reinforced elements ( 21 , 22 ) are pultruded carbon fibre reinforced plastic planks.
19. A wind turbine blade comprising the spar cap according to claim 1 .