Pultruded fibrous composite strips having corrugated profiles for wind turbine blade spar caps

A spar cap for a wind turbine rotor blade, the spar cap comprising a plurality of pultruded fibrous composite strips stacked with one or more similar strips to form a stack of pultruded fibrous composite strips, wherein each pultruded fibrous composite strip comprises a substantially constant cross-section defined by a first longitudinally extending side that is mutually opposed by a second longitudinally extending side and by a first longitudinal edge and a second longitudinal edge, wherein the first longitudinally extending side and the second longitudinally extending side include a first abutment surface and a second abutment surface, respectively, wherein, at least one of the first abutment surface and the second abutment surface has a corrugated profile such that a plurality of longitudinally extending grooves are defined on the first abutment surface and/or the second abutment surface, wherein the corrugated profile is defined by a series of curved ridges adjacent to the plurality of longitudinally extending grooves, wherein the first abutment surface and/or the second abutment surface having the corrugated profile comprises one or more trenches formed therein and extending between at least two adjacent longitudinally extending grooves of the plurality of longitudinally extending grooves, wherein the one or more trenches are configured to fluidly connect the two adjacent longitudinally extending grooves, and

• an interstitial space between the plurality of pultruded fibrous composite strips, the interstitial space comprising the plurality of longitudinally extending grooves and a space between the plurality of pultruded fibrous composite strips in a transverse direction to each strip and adjacent the plurality of longitudinally extending grooves;
• wherein the stack of the plurality of pultruded fibrous composite strips are oriented such that one of the first abutment surface and the second abutment surface of one of the plurality of pultruded fibrous composite strips of the stack faces abutment surfaces of an adjacent strip of the stack.

A method for making a spar cap for a wind turbine rotor blade, the method comprising:

• providing a plurality of pultruded fibrous composite strips, wherein each pultruded fibrous composite strip comprises a substantially constant cross-section defined by a first longitudinally extending side that is mutually opposed by a second longitudinally extending side and by a first longitudinal edge and a second longitudinal edge, wherein the first longitudinally extending side and the second longitudinally extending side include a first abutment surface and a second abutment surface, respectively, wherein, at least one of the first abutment surface and the second abutment surface has a corrugated profile such that a plurality of longitudinally extending grooves are defined on the first abutment surface and/or the second abutment surface, wherein the corrugated profile is defined by a series of curved ridges adjacent to the plurality of longitudinally extending grooves, wherein the corrugated profile is defined by a series of curved ridges adjacent to the plurality of longitudinally extending grooves such that an interstitial space is created between each pultruded fibrous composite strip and a neighboring strip, the interstitial space comprising the plurality of longitudinally extending grooves and a space between each pultruded fibrous composite strip and the neighboring strip that extends in a transverse direction to each pultruded fibrous composite strip and adjacent the plurality of longitudinally extending grooves, wherein the first abutment surface and/or the second abutment surface having the corrugated profile comprises one or more trenches formed therein and extending between at least two adjacent longitudinally extending grooves of the plurality of longitudinally extending grooves, wherein the one or more trenches are configured to fluidly connect the two adjacent longitudinally extending grooves;
• stacking the plurality of pultruded fibrous composite strips in a mould to form a stack of pultruded fibrous composite strips such that, in the stack, one of the first abutment surface and the second abutment surface of one of the plurality of pultruded fibrous composite strips of the stack faces abutment surfaces of an adjacent strip of the stack to define longitudinally extending resin flow channels therebetween, wherein each of the resin flow channels comprises at least one of the plurality of longitudinally extending grooves defined on one of the first abutment surface and the second abutment surface facing each other in the stack;
• supplying resin to the stack and causing the resin to infiltrate into the longitudinally extending resin flow channels;
• and
• curing the resin to bond adjacent strips together.