Perforated vacuum membrane for fibre reinforced laminates

Abstract

A composite component for a wind turbine blade is provided. The composite component includes a stack of at least one fiber layer and a membrane which has a first surface and a second surface which is an opposite surface with respect to the first surface. The membrane is arranged with the first surface on top of the stack. The membrane is perforated with openings, wherein the membrane is formed in such a way that the openings are permeable for a fluid flowing along a first direction directing from the first surface to the second surface and impermeable for a fluid flowing along a second direction directing from the second surface to the first surface.

Claims

1. A composite component for a wind turbine blade, wherein the composite component is configured to form at least part of the wind turbine blade, the composite component comprising: a stack of at least one fibre layer, and a membrane which has a first surface and a second surface which is an opposite surface with respect to the first surface, wherein the membrane is arranged with the first surface on top of the stack, wherein the membrane is perforated with openings, wherein the membrane is formed such that the openings are permeable for a fluid flowing along a first direction directed from the first surface to the second surface, and impermeable for a fluid flowing along a second direction directed from the second surface to the first surface wherein the membrane comprises at least one elastic seal lip surrounding one of the openings at the second surface wherein the elastic seal lip is formed such that the seal lip is pressed together to close the respective opening if a second pressure (Pb) of the fluid applied at the first surface is lower than a first pressure (Pa) of the fluid applied at the second surface, and the seal lip is elastically deformed and edges of the seal lip are bent away from the respective opening to open the respective opening if the second pressure (Pb) of the fluid applied at the first surface is higher than the first pressure (Pa) of the fluid applied at the second surface.

2. The composite component according to claim 1, wherein the fluid flowing along the first direction is a first fluid and wherein the fluid flowing along the second direction is a second fluid different than the first fluid.

3. The composite component according to claim 2, wherein the first fluid is resin and the second fluid is air and wherein the at least one fibre layer of the stack is a plurality of fibre layers.

4. The composite component according to claim 1, further comprising a further stack with at least one further fibre layer arranged on the second surface of the membrane.

5. The composite component according to claim 1, wherein the membrane comprises a degradable material.

6. The composite component according to claim 1, wherein at least one of the openings has a cone-like shape with a base area and a cone end, wherein the base area is formed at the first surface and the cone area is formed at the second surface, wherein the seal lip is formed at the cone area.

7. A method for manufacturing the composite component of claim 1, wherein the composite component comprises the membrane and the stack of at least one fibre layer, the method comprising arranging the membrane with the first surface on top of the stack.

8. The method according to claim 7, further comprising: pressing the elastic seal lip together based on the second pressure (Pb) of the fluid applied at the first surface being lower than the first pressure (Pa) of the fluid applied at the second surface; and closing the opening based on the pressing the elastic seal lip together such that the opening is impermeable to the fluid flowing along the second direction.

9. The method according to claim 7, further comprising: deforming the elastic seal lip by bending the edges of the seal lip away from the respective opening based on the second pressure (Pb) of the fluid applied at the first surface being higher than the first pressure (Pa) of the fluid applied at the second surface; and opening the opening based on the deforming the elastic seal lip such that the opening is permeable to the fluid flowing along the first direction.

10. The method according to claim 7, further comprising arranging a further stack of at least one further fibre layer onto the second surface of the membrane.

11. The method according to claim 7, further comprising arranging the stack and the membrane into a mould, and applying an underpressure between the membrane and the mould such that the membrane and the stack are pressed against the mould.

12. The method according to claim 11, further comprising applying a further mould such that the stack and the membrane are located between the mould and the further mould.

13. The method according to claim 7, further comprising injecting resin through the at least one fibre layer of the stack and the membrane along the first direction.

14. The method according to claim 7, further comprising degrading the membrane by a physical and/or chemical degradation of the membrane.

15. A composite component for a wind turbine blade, wherein the composite component is configured to form at least part of the wind turbine blade, the composite component comprising a first stack of at least one fibre layer, a second stack of at least one fibre layer, a membrane which has a first surface and a second surface which is an opposite surface with respect to the first surface, wherein the membrane is arranged with the first surface on top of the first stack and with the second stack arranged on the second surface, wherein the membrane is perforated with openings, wherein the membrane is formed such that the openings are permeable for a fluid flowing along a first direction directed from the first surface to the second surface, and impermeable for a fluid flowing along a second direction directed from the second surface to the first surface; wherein the membrane comprises an elastic seal lip surrounding one of the openings, wherein the elastic seal lip is pressed together based on a second pressure (Pb) of the fluid applied at the first surface being lower than a first pressure (Pa) of the fluid applied at the second surface such that the opening is impermeable for the fluid flowing along the second direction and wherein the elastic seal lip is elastically deformed and edges of the seal lip are bent away from the opening based on the second pressure (Pb) of the fluid applied at the first surface being greater than the first pressure (Pa) of the fluid applied at the second surface such that the opening is permeable for the fluid flowing along the first direction.

16. The composite component according to claim 15, wherein at least one of the openings has a cone-like shape with a base area and a cone end, wherein the base area is formed at the first surface and the cone area is formed at the second surface, wherein the seal lip is formed at the cone area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The aspects defined above and further aspects of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

(2) FIG. 1 shows a schematical view of a layer structure of a composite component between two moulds according to an exemplary embodiment of the present invention;

(3) FIG. 2 shows schematically a membrane in an impermeable state according to an exemplary embodiment of the present invention; and

(4) FIG. 3 shows a schematical view of a membrane in a permeable state according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

(5) The illustrations in the drawings are schematical. It is noted that in different figures, similar or identical elements are provided with the same reference signs.

(6) FIG. 1 shows a composite component 100 for a wind turbine blade, wherein the composite material 100 comprises a stack 101, a membrane 110 and optionally a further stack 106. The stack 101 comprises at least one fibre layer 102, 103, 105. Furthermore, the stack may comprise optionally a core material 104 which may be interposed between the respective fibre layers 103, 105.

(7) In FIG. 1 to FIG. 3, in particular the membrane 110 is shown schematically with a large thickness in order to outline the perforation with openings 113. However, the membrane 110 may comprise the thickness of the fibre layer 102, 103, 105 or may comprise a smaller thickness than the fibre layer 102, 103, 105.

(8) The membrane 110 has a first surface 111 and a second surface 112 which is an opposite surface with respect to the first surface 111. The membrane 110 is arranged with the first surface 110 on top of the stack 101.

(9) The membrane 110 is perforated with openings 113 which are formed in such a way that the openings 113 are permeable for fluid (such as resin) flowing along a first direction 114 directing from the first surface 111 to the second surface 112 and which openings 113 are impermeable for a fluid (such as air) flowing along a second direction 115 directing from the second surface 112 to the first surface 111.

(10) A further stack 106 is optionally arranged on the second surface 112 of the membrane 110. The further stack 106 may comprise further fibre layers 107, 108.

(11) As can be taken from FIG. 1, the stack 101 which may comprise the fibre layers 102, 103, 105 and for example a core material 104 may be arranged onto a surface of the mould 121. The stack 101 is covered by the membrane 110. At this step, the fibre layers 102, 103, 105, 107, 108 and the membrane 110 are dry and also movable with respect to each other. In order to prevent an undesired relative movement e.g. between the stack 101 and the membrane 110, an underpressure is applied between the membrane 110 and the mould 121 for pressing and thus fixing the membrane 110 and the stack 101 to the mould 121.

(12) In order to support the generation of the underpressure between the membrane 110 and the mould 121, the membrane 110 is aligned in such a way that fluid (such as air) is not flowable along the second direction 115 from the surroundings of the membrane 110 to the inner surface of the mould 121. Hence, the membrane 110 functions as a barrier layer for the fluid (air) and is almost airtight. Hence, a proper and temporary fixation of the membrane 110 and the stack 101 onto the mould 121 is achieved.

(13) After positioning the mould 121 at the desired location and/or after locating a further mould 121 onto the membrane 110 or onto the further stack 106, the composite component 100 is fixed between the mould 121 and the further mould 122. If the stack 101, the further stack 106 and the membrane 110 are clamped and thus fixed between the mould 121 and the further mould 122, a transfer moulding procedure may be started. Hence, a fluid, such as a resin, is injected between the mould 121 and the further mould 122. In particular, the resin is injected starting from the mould 121 along the first direction 114 through the stack 101. Because the openings 113 are permeable for the resin flowing along the first direction 114, the resin may flow through the openings 113 such that the fibre layers 102, 103, 105, the membrane 110 itself and optionally the further fibre layers 107, 108 are homogeneously soaked and wetted with the resin. Hence, the membrane 110 does not function as a barrier layer for the fluid (resin) flowing along the first direction 114.

(14) After the stack 101, the membrane 110 and optionally the further stack 106 is soaked sufficiently with resin, the composite component 100 may be cured by applying curing temperature (if necessary) to the composite material 100.

(15) The membrane 110 may comprise elastic seal lips 116 surrounding the openings 113 at the second surface 112. If a fluid flows along the second direction 115, the seal lip 116 surrounding an opening 113 is pressed together such that the opening 113 is impermeable for the fluid. If the fluid flows along the first direction 114, the seal lip 116 is elastically deformed and edges of the seal lip 116 are bent away, such that the fluid is flowable through the openings 113 along the first direction 114.

(16) FIG. 2 shows a detailed view of the membrane 110, wherein the openings 113 are closed by the seal lips 116 and thus impermeable for the fluid flowing along the second direction 115. As can be taken from FIG. 2, the fluid flows along the second direction 115, if a first pressure Pa acting on the second surface 112 of the membrane 110 is higher than the second pressure Pb acting on the first surface 111 of the membrane 110. This situation is generated for example when applying the vacuum pump for sucking air out of a region between the membrane 100 and the mould 121.

(17) The openings 113 are formed with a cone-like shape. In FIG. 2, a cross-sectional view of the membrane 100 and the openings 113 is shown. The cone-like shaped openings 113 have a larger base area and a smaller cone end. The base area is formed at the first surface 111 and the cone area is formed at the second surface 112. Respective seal lips 116 surrounding a respective opening 113 are formed at the cone area.

(18) In FIG. 3, the membrane 110 is shown in a permeable state. The openings 113 are opened because the edges of the seal lips 116 are bended away by the fluid acting on the seal lip 116. Hence, the seal lips 116 are permeable for the fluid flowing along the first direction 114. As can be taken from FIG. 3, the fluid flows along the first direction 114, if the first pressure Pa acting on the second surface 112 of the membrane 110 is lower than the second pressure Pb acting on the first surface 111 of the membrane 110. This situation is generated for example when pressing the resin for soaking and wetting the stack 101 into a region between the membrane 100 and the mould 121.

(19) Summarizing, the membrane 110 is placable on top of the stack 101 for forming a closed barrier to air for providing a vacuum consolidation of the complete stack 101. On the other side, the membrane 110 is permeable in order to ensure a proper soaking of the stack 101, the membrane 110 and the further stack 106. The membrane 110 may be made partially heterogeneous over the thickness in order to be able to react differently depending on pressure differences between the first surface 111 and the second surface 112. This is obtained by introducing valve-like, cone-shaped openings 113. When exposed to a positive pressure difference from Pa to Pb (PaPb as shown in FIG. 2) the membrane is closed and (almost) vacuum tight. However, when a negative pressure difference occurs (PaPb, FIG. 3) e.g. during resin injection, the membrane 110 opens up and a flow of fluid (resin) through the openings 113 is possible. Hence, resin is provided at the stacks 101, 106 where resin is needed.

(20) The membrane 110 may form an integrated part of the final structure of the composite component. The membrane 110 may form a surface layer of the composite component 100, because the membrane 110 may be sufficiently wetted and soaked with resin by the permeability properties of the membrane 110.

(21) It should be noted that the term comprising does not exclude other elements or steps and a or an does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.