Abstract
A method of repairing a damaged spar cap of a wind turbine blade of a wind turbine, the damaged spar cap including carbon fiber-reinforced plastic and the method having the steps of: removing a damaged carbon fiber-reinforced plastic part from the damaged spar cap to obtain a corresponding recess in the damaged spar cap, applying an adhesive to the recess, and fitting at least one patch including carbon fiber-reinforced plastic into the recess, is provided.
Claims
1. A method of repairing a damaged spar cap of a wind turbine blade of a wind turbine, the damaged spar cap comprising carbon fiber-reinforced plastic, the method comprising: removing a damaged carbon fiber-reinforced plastic part from the damaged spar cap to obtain a corresponding recess in the damaged spar cap; applying an adhesive to the corresponding recess; fitting at least one patch comprising carbon fiber-reinforced plastic into the corresponding recess, wherein the carbon fiber-reinforced plastic of the at least one patch are pultruded carbon elements; and joining the at least one patch with the spar cap to obtain a repaired spar cap.
2. The method according to claim 1, wherein the corresponding recess is tapered in at least one direction with a tapering angle and at least one of the at least one patches is chamfered in at least one direction with a chamfering angle.
3. The method according to claim 2, wherein at least one of the at least one direction of the tapering and/or at least one of the at least one direction of the chamfering is a fiber direction of the carbon fiber-reinforced plastic.
4. The method according to claim 2, wherein the tapering angle corresponds to the chamfering angle.
5. The method according to claim 1, wherein the adhesive is applied continuously on at least 80% of a surface of the corresponding recess.
6. The method according to claim 1, wherein the adhesive is an electrically conductive adhesive film.
7. The method according to claim 1, wherein the at least one patch is provided with a peel-ply on a top surface and/or a bottom surface of the patch, whereby the peel-ply is removed prior to fitting the at least one patch into the corresponding recess.
8. The method according to claim 1, wherein the carbon fiber-reinforced plastic of the damaged spar cap are provided as pultruded carbon elements.
9. The method according to claim 8, wherein the damaged spar cap and/or the at least one patch are provided with an array of at least two pultruded carbon elements arranged parallel to each other in a fiber direction of the carbon fiber-reinforced plastic.
10. The method according to claim 8, wherein the damaged spar cap and/or the at least one patch are provided with a stack of at least two pultruded carbon elements arranged stacked on top of each other.
11. The method according to claim 1, wherein at least two patches are being fitted into the corresponding recess, whereby the adhesive is applied on top of at least one of the at least two patches.
12. The method according to claim 1, wherein the damaged carbon fiber-reinforced plastic is removed from the damaged spar cap by means of abrasion and/or sanding.
13. The method according to claim 1, wherein the at least one patch is joined with the damaged spar cap by means of vacuum bagging using a vacuum bagging assembly.
14. The method according to claim 1, wherein the at least one patch is joined with the damaged spar cap by applying heat to the at least one patch by means of a heating blanket.
15. The method according to claim 1, wherein at least one doubler plate is being arranged on top of the at least one patch and the damaged spar cap and the at least one doubler plate is being joined with the at least one patch and the damaged spar cap.
Description
BRIEF DESCRIPTION
(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
(2) FIG. 1 depicts a sectional view along a transversal plane of a wind turbine blade;
(3) FIG. 2 depicts a perspective view of a patch according to a first embodiment;
(4) FIG. 3 depicts a sectional long side view of the patch from FIG. 2;
(5) FIG. 4 depicts a sectional short side view of the patch from FIG. 2;
(6) FIG. 5 depicts a perspective view of a patch according to a second embodiment;
(7) FIG. 6 depicts a sectional long side view of the patch from FIG. 5;
(8) FIG. 7 depicts a sectional short side view of the patch from FIG. 5;
(9) FIG. 8 depicts a perspective view of a step of the method according to an embodiment;
(10) FIG. 9 depicts a side sectional view of the step of the method according to the embodiment from FIG. 8;
(11) FIG. 10 depicts a side view on a further step of the method according to the embodiment following the step from FIG. 9;
(12) FIG. 11 depicts a side sectional view on yet another step of the method according to the embodiment following the step from FIG. 10; and
(13) FIG. 12 depicts a side view on a patch according to a third embodiment.
(14) Same aspect in FIGS. 1 to 12 are denominated with the same reference number. If there is more than one aspect of the same kind in one of the figures, the aspects are numbered in ascending order with the ascending number of the aspect being separated from its reference number by a dot.
DETAILED DESCRIPTION
(15) FIG. 1 is a sectional view along a transversal plane of a first embodiment of a wind turbine blade 10 according to the embodiment of the present invention. The wind turbine blade 10 has a trailing edge 11 and a leading edge 12. The wind turbine blade 10 comprises a shell 20 and a spar 30. The spar 30 comprises two spar caps 40.1, 40.2, which face each other and are connected to one another by means of a spar web 35.
(16) FIG. 2 is a perspective view of a patch 50 according to a first embodiment, which may be used in the method according to the embodiment of the present invention. The patch 50 is a pultruded carbon element 51 with unidirectional fibers arranged in the direction of the arrow F. The patch 50 comprises a peel-ply 52.1 arranged on a top surface of the patch 50 and a peel-ply 52.2 arranged on a bottom surface of the patch 50. The patch 50 has a thickness T.sub.50 in the range of 1 mm to 5 mm and a width W.sub.50 in the range of 50 mm to 300 mm.
(17) FIG. 3 is a sectional long side view of the patch 50 from FIG. 2 along cutting line III-III. FIG. 4 is a sectional short side view of the patch 50 from FIG. 2 along cutting line IV-IV.
(18) FIG. 5 is a perspective view of a patch 50 according to a second embodiment, which may be used in the method according to the embodiment of the present invention. The patch 50 is a pultruded carbon element 51 with unidirectional fibers in the direction of the arrow F. The patch 50 comprises a peel-ply 52.1 arranged on a top surface of the patch 50 and a peel-ply 52.2 arranged on a bottom surface of the patch 50. The patch 50 has a thickness T.sub.50 in the range of 1 mm to 5 mm and a width W.sub.50 in the range of 50 mm to 300 mm. The patch 50 is chamfered on the bottom surface of the patch 50 in the fiber direction F. The chamfering is provided at the long sides of the patch 50 with a middle portion of the patch 50 not being chamfered, i.e. arranged parallel to the top surface.
(19) FIG. 6 is a sectional long side view of the patch 50 from FIG. 5 along cutting line VI-VI. Here, the chamfering angles Θ.sub.50.1, Θ.sub.50.2 of the chamfers are marked. Both chamfering angles Θ.sub.50, Θ.sub.50.2 are in the range of 1° to 5° and are equal to each other in this embodiment.
(20) FIG. 7 is a sectional short side view of the patch 50 from FIG. 5 along cutting line VII-VII. Because the middle portion of the patch 50 along cutting line VII-VII is not chamfered but arranged parallel to the top surface of the patch 50, FIG. 7 is equal to FIG. 4.
(21) FIG. 8 is a perspective view on a step of the method according to the embodiment of the present invention. In this step, two patches 50.1, 50.2 are fitted into a recess 43 of the spar cap 40, which is one of the spar caps 40.1, 40.2 of the wind turbine blade 10 from FIG. 1. The spar cap 40 comprises an array of a first stack of pultruded carbon elements 41.1, 41.2, 41.3, 41.4 and a second stack of pultruded carbon elements 41.5, 41.6, 41.7, 41.8, the first and second stack being arranged parallel to each other in the fiber direction F of the pultruded carbon elements 41.1 . . . 41.8. Further, the patches 50.1, 50.2 comprise an array of pultruded carbon elements 51.1, 51.2, with the pultruded carbon elements 51 of the patch 50.2 not being visible in this perspective because they are covered by the patch 50.1. Wedge elements 42.1 and 42.2 are arranged in a transverse direction adjacent to the pultruded carbon elements 41.1 . . . 41.8. The recess 43 within both stacks of the pultruded carbon elements 41.1 . . . 41.8 corresponds to fit the patches 50.1, 50.2. In particular, the recess 43 is tapered in the fiber direction F with tapering angles Θ.sub.43.1, Θ.sub.43.2, which are equal to each other in this embodiment. The tapering angles Θ.sub.43.1, Θ.sub.43.2 correspond to chamfering angles Θ.sub.50.1 . . . Θ.sub.50.4 of the patches 50.1, 50.2. The patches 50.1, 50.2 are fitted with their lengths L.sub.50.1, L.sub.50.2 measured in the fiber direction F into the recess 43.
(22) FIG. 9 is a side sectional view on the step of the method according to the embodiment of the present invention from FIG. 8 along cutting line IX-IX of the spar cap 40 and the patch 50. In this embodiment, portions of the first two pultruded carbon elements 41.1, 41.2 of the first array of the spar cap 40 have been removed to form the recess 43. Adhesive 60.1 has been applied between the patches 50.1, 50.2 and adhesive 60.2 has been applied between the patch 50.2 and the spar cap 40. The thickness T.sub.50.1 of the patch 50.1 corresponds to the thickness T.sub.41.1 of the pultruded carbon element 41.1. Further, the thickness of the patch 50.2 corresponds to the thickness of the pultruded carbon element 41.2.
(23) FIG. 10 is a side view on a further step of the method according to the embodiment of the present invention following the step from FIG. 9. Here, the patches 50.1, 50.2 are joined with the spar cap 40 by means of vacuum bagging using a vacuum bagging assembly 80 arranged on top of the patches 50.1, 50.2 and the spar cap 40. The vacuum bagging assembly comprises a vacuum source (not shown), a vacuum bag 81, two vacuum ports 82.1, 82.2 fitted to the vacuum bag 81 and a lay-up consisting of a breather material 83.1, 83.2, 83.3, a non-perforated release foil 86, a bleeder material 87 and a perforated release foil 88. The lay-up is enclosed by the vacuum bag 81, which is sealed by means of sealants 89.1, 89.2, 89.3, 89.4 to the spar cap 40. A thermocouple 84 and a heating blanket 85 are arranged between the breather material 83.1, 83.2, 83.3 and the non-perforated release foil 86. Power and control lines of the thermocouple 84 and heating blanket 85 are led out of the vacuum bag 81. The thermocouple 84 and heating blanket 85 may be connected to a control unit (not shown) for temperature-adjusted control of the heating blanket 85.
(24) In operation, the vacuum bag 81 is evacuated to compact the lay-up under atmospheric pressure. The breather material 83.1, 83.2, 83.3 acts as a continuous vacuum path but does not come in contact with adhesive from the precured patches 50.1, 50.2. The bleeder material 87 allows the escape of excess gas and resin during cure. The effect of the perforated release film 88 is that it restricts the amount of resin bleed that is able to pass through the perforated release film 88. The non-perforated release foil 86 is in direct contact with the heating blanket 85, so that it is not bonded. After operation, the vacuum bag assembly 80 can be removed and the repair has been performed, so that a repaired spar cap 40 is obtained.
(25) FIG. 11 is a side sectional view on a further step of the method according to the embodiment of the present invention following the step from FIG. 10. Here, the patches 50.1, 50.2 have been joined with the spar cap 40 and a repaired spar cap 40 was obtained. Further, doubler plates 70.1, 70.2 made from pultruded carbon elements have additionally been arranged on top of the patch 50.1 and the spar cap 40, in particular on top of the pultruded carbon element 41.1 of the spar cap 40, to strengthen the joint of the patches 50.1, 50.2 with the spar cap 40. By means of adhesive 60.3, 60.4 the doubler plates 70.1, 70.2 are joined with the spar cap 40 and the patch 50.1. The doubler pates 70.1, 70.2 are provided with a tapering having a tapering angle Θ.sub.70.
(26) FIG. 12 is a side view on a patch 50 according to a third embodiment. Here, first chamfers are provided having a first chamfering angle Θ.sub.50.1A, Θ.sub.50.2A being equal to one another at the long sides of the patch 50. Second chamfers having second chamfering angles Θ.sub.50.1B, Θ.sub.50.2B being greater than the first chamfering angles Θ.sub.50.1A, Θ.sub.50.2A are provided adjacent to the first chamfers in a direction pointing towards a middle portion of the patch 50. The bottom surface of the middle portion of the patch 50 is parallel to the top surface of the patch 50.
(27) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
(28) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
