Bonded joint inspection of wind turbine blades

Abstract

The invention relates to a method of manufacturing a wind turbine blade (10) and a method of inspecting a glued assembly (100) of a first wind turbine blade component and a second wind turbine blade component. A first blade member (36) and a second blade member (50) are provided, and at least one ultrasound imaging marker (70) is attached to the second blade member (50). A second blade member (50) is bonded to the first blade member (36) along at least one adhesive joint (72), and an ultrasound image (74) of the adhesive joint (72) and at least a portion of the bonded first and second blade members is obtained. An ultrasound imaging marker (70) may be identified on the ultrasound image to verify the integrity of an adhesive joint (72) between the first blade member and the second blade member.

Description

Technical Field

[0001] The invention relates to a wind turbine blade, a method of manufacturing a wind turbine blade, a system for inspecting a wind turbine blade and a method of inspecting a glued assembly of a first wind turbine blade component and a second wind turbine blade component. Background Art

[0002] Climate change has created an urgent need for sustainable energy, bringing wind energy to the forefront as a cost-effective and clean energy source. A wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades that capture the kinetic energy of the wind using the known airfoil principle. As energy demands increase, modern wind turbines may have power ratings of over 10 MW and may have rotor blades that exceed 100 meters in length.

[0003] Wind turbine rotor blades are typically made of fiber reinforced polymer materials and include a pressure side shell half and a suction side shell half, also referred to as a blade half. The cross-sectional profile of a typical blade includes an airfoil for generating air flow resulting in a pressure difference between the two sides. The resulting lift generates torque for generating electricity.

[0004] The shell halves of rotor blades are typically manufactured using blade molds. First, a blade gel coat or primer is applied to the mold. Subsequently, fiber reinforcements and / or fabrics are placed in the mold, followed by resin infusion. A vacuum is typically used to draw the epoxy resin material into the mold. Alternatively, prepreg technology may be used, in which fibers or fabrics pre-impregnated with resin form a uniform material that can be introduced into the mold. Several other molding techniques, including compression molding and resin transfer molding, are known for manufacturing wind turbine blades. The resin is allowed to cure, and then one or more shear webs or box spars are positioned in the shell before the shell halves are joined. The shell halves containing the shear webs are then assembled together by bonding them together along corresponding bond lines between the inner shell surface (such as the spar cap surface) and the (one or more) shear webs, as well as along the trailing and leading edges of the blade. The bond lines are generally formed by applying a suitable bonding paste or adhesive along the specified bonding locations.

[0005] High quality bond lines are crucial to the performance and service life of wind turbine blades. Separation of bond lines within a blade may lead to damage or complete failure of the wind turbine. Therefore, precise process control and subsequent bond line inspection are important.

[0006] However, once the blade halves are assembled, it may be difficult to precisely control the adhesive bond lines of the respective joints due to limited access. Therefore, it is necessary to inspect such bond lines during and / or after blade manufacture. To this end, it is known to use ultrasonic testing (such as ultrasonic testing B-scan techniques) to inspect the bond lines along the length of the blade. As used herein, the term "B-scan image" may refer to a reconstructed 2-D image based on raw data of a sample 2-D slice collected during imaging. By inspecting the resulting thickness cross-section of the blade at any given location, bond line defects may be observed as deviations from the expected thickness and / or depth of the joint.

[0007] However, such known inspection techniques are prone to false positive bonding inferences, which may result in defective blades. This is particularly true where there is considerable variation or tolerance regarding acceptable bond joint thickness. For example, if the bond line thickness is in a similar mm range to the thickness of the part bonded to the shell (such as the mounting flange of the shear web), the thickness / depth measurement obtained by ultrasonic testing may be inconclusive.

[0008] Therefore, a first object of the present invention is to provide a method of manufacturing and inspecting a wind turbine blade which allows an unambiguous verification of the integrity of the bonded joint.

[0009] Another object of the present invention is to provide a wind turbine blade which can be inspected more effectively with respect to the integrity of the bond joints. Summary of the invention

[0010] The present invention solves one or more of the above objects by providing a method for manufacturing a wind turbine blade, the method comprising the following steps: providing a first blade member and a second blade member, attaching at least one ultrasound imaging marker to the second blade member, bonding the second blade member to the first blade member along at least one bond joint, An ultrasound image of the bonded joint and at least a portion of the joined first and second blade components is obtained, and an ultrasound imaging marker is identified on the ultrasound image to verify the integrity of the bonded joint between the first and second blade components.

[0011] It was found that the method allows ultrasonic testing of bonded joints, wherein improved differentiation between ultrasonic signals is provided. It was found that this reduces or avoids false positive bond inferences, and leads to an overall improvement in quality control and blade structural stability. In particular when bonded joints within wind turbine blades are used to join blade components having a partial thickness similar to the acceptable thickness tolerance of the bonded joint, the measurement of the depth of the back wall echo signal is not sufficient to exclude detachment of the blade component. Therefore, the use of ultrasonic imaging markers attached to the blade component allows the blade component to be unambiguously identified on the ultrasonic image, and thus the integrity of the bonded joint to be unambiguously verified.

[0012] A wind turbine blade manufactured according to the method of the present invention typically has a profile contour comprising a pressure side and a suction side, and having a chord leading edge and a trailing edge, wherein the chord has a chord length extending between the leading edge and the trailing edge, wherein the wind turbine blade extends in a spanwise direction between a root end and a tip end. The method will typically include molding a suction side shell half and a pressure side shell half, each shell half may be a first blade component, and the suction side shell half and the pressure side shell half adhesively connected along corresponding join lines at the leading edge and the trailing edge. Preferably, the suction side shell half and the pressure side shell half are produced by vacuum assisted resin transfer molding. Typically, the shell molding operation includes arranging a fiber layup (e.g., including glass fibers), which includes one or more fiber layers on a mold surface to form a shell half structure including an aerodynamic outer side surface and an opposing inner side surface. The fiber layup is typically injected or infused with resin and then cured.

[0013] Typically, the blade structure is further reinforced using a plurality of support members, such as shear webs or box beams, which are arranged within the blade and to which the two shell halves can be joined. The shear webs typically serve to reinforce the blade structure and prevent excessive bending or buckling. Each of the shear webs or box beams can be a second blade member. Typically, the shear webs are placed on a spar cap or main laminate that forms part of the inner surface of the shell halves. Typically, each shear web will include a body and two opposing mounting flanges for mounting the shear web between the two shell halves. One mounting flange can be joined to an open first shell half, and then when the two shell halves are joined together, a second opposing mounting flange of the shear web is joined to the second shell half.

[0014] In a preferred embodiment, the first blade component is a blade shell portion, such as a suction side shell half or a pressure side shell half, and the second blade component is a shear web, wherein preferably a mounting flange of the shear web is bonded to the inner surface of the shell portion. Preferably, the shear web is an I-shaped shear web having a web body, and a first mounting flange at a first end of the web body and a second mounting flange at a second end of the web body. In some embodiments, the shear web has a C-shaped cross-section.

[0015] In other embodiments, the first blade component is a suction side shell half, and the second blade component is a pressure side shell half. In some embodiments, the first blade component is a blade shell portion, such as a shell half, and the second blade component is a shear web flange. In some embodiments, the first blade component is a blade shell portion, such as a shell half, and the second blade component is a receiving box of a split blade.

[0016] At least one ultrasonic imaging marker is attached to the second blade member, such as to the shear web mounting flange. In a preferred embodiment, the step of attaching at least one ultrasonic imaging marker to the second blade member includes adhesively bonding the ultrasonic imaging marker to the outer surface of the second blade member. Preferably, the ultrasonic imaging marker is attached to the mounting flange surface opposite to the surface for bonding the mounting flange to the shell portion, that is, to the surface facing away from the mounting area on the shell portion. Preferably, the ultrasonic imaging marker is attached to the second blade member, such as to the shear web mounting flange, before the step of bonding the second blade member to the first blade member along at least one adhesive joint. However, in other embodiments, the ultrasonic imaging marker may be attached to the second blade member, such as to the shear web mounting flange, after the step of bonding the second blade member to the first blade member along at least one adhesive joint.

[0017] In another preferred embodiment, the step of attaching at least one ultrasonic imaging marker to the second blade component comprises integrating the ultrasonic imaging marker into the second blade component. If the second blade component is a shear web having a web body and two opposing mounting flanges, the ultrasonic imaging marker may be integrated into the web body, for example as a portion having an arched or domed surface extending along the length of the web body. According to a preferred embodiment, the ultrasonic imaging marker is a structural embedded core segment of the shear web, the core segment comprising a curved, arched or domed surface, preferably wherein the curved, arched or domed surface faces towards the bonded joint between the shear web and the shell portion.

[0018] In some embodiments, the ultrasonic imaging marker comprises a foam element or is constituted by a foam element. In a preferred embodiment, the foam element has an arched or semicircular cross-section. In some embodiments, the foam element is shaped as a hemisphere, preferably wherein the flat surface of the hemisphere is adhered to the second blade member. Preferably, the hemisphere has a diameter of 5-25 mm. In other embodiments, the ultrasonic imaging marker is box-shaped or has a prism shape. In some embodiments, the ultrasonic imaging marker may have a rectangular or triangular cross-section. In some embodiments, the ultrasonic imaging marker may have a circular or semicircular cross-section. Preferably, the ultrasonic imaging marker extends substantially along the entire length of the second blade member, for example, along substantially the entire length or span-wise range of the shear web.

[0019] In a preferred embodiment, the ultrasound imaging marker comprises or consists of a polymer foam material (such as PET foam), which preferably has a strength of 40-60 kg / m 3 In a preferred embodiment, the ultrasound imaging marker has a diameter or maximum dimension of 5-25 mm. In a preferred embodiment, the ultrasound imaging marker includes at least one arched or dome-shaped surface. In one embodiment, the ultrasound imaging marker includes a substantially flat first surface and a second surface having an arched shape, such as a dome-shaped surface. It is believed that such an arched shape (such as a dome-shaped surface) provides a particularly advantageous scattering pattern that can be used as a characteristic pattern on an ultrasound image to clearly identify the marker.

[0020] It is particularly preferred that the ultrasound imaging marker is a relatively lightweight element which does not significantly increase the weight of the wind turbine blade. In some embodiments, the weight of the ultrasound imaging marker is less than 10 kg, preferably less than 5 kg, such as less than 3 kg. The density of the ultrasound imaging marker is preferably 60 kg / m 3 or less, preferably 50kg / m 3 or smaller.

[0021] In a preferred embodiment, the ultrasound imaging marker is capable of attenuating ultrasound waves. In a preferred embodiment, the ultrasound imaging marker is capable of absorbing ultrasound waves. In a preferred embodiment, the ultrasound imaging marker is capable of scattering ultrasound waves.

[0022] It is particularly preferred that the first blade component is a blade shell portion, wherein the second blade component is a shear web, the shear web comprising at least one mounting flange for adhesively attaching the shear web to a shear web mounting area on the inner surface of the blade shell portion, wherein the mounting flange comprises a first surface facing the shear web mounting area and an opposing second surface, wherein the ultrasonic imaging marker is attached to the second surface of the mounting flange. For an I-shaped shear web, the second surface will typically be subdivided into two opposite parts separated by the web body of the shear web, i.e., typically subdivided into a first part closer to the trailing edge of the blade and a second part closer to the leading edge of the blade. In some embodiments, corresponding ultrasonic imaging markers are attached to both parts of this subdivided second surface of the mounting flange. In other embodiments, the ultrasonic imaging marker is attached to only one of the two parts of this subdivided second surface of the mounting flange.

[0023] In a preferred embodiment, the second blade member comprises a portion having a thickness of 2-30 mm, preferably 2-20 mm, most preferably 2-10 mm, wherein said portion is bonded to the adhesive joint. It is particularly preferred that one or more ultrasound imaging markers are attached to or incorporated into said portion. In a preferred embodiment, the mounting flange of the shear web has a thickness of 2-10 mm.

[0024] The second blade member is bonded to the first blade member along at least one bonded joint, such as along a glued flange. The bonded joint may be a leading edge bonded joint, a trailing edge bonded joint, or most preferably a blade shell portion / shear web bonded joint. The bonded joint may be formed by a suitable glue or bonding paste. In a preferred embodiment, the bonded joint has a thickness in the range from 1 mm to 25 mm, such as from 1 mm to 15 mm, preferably from 3 mm to 10 mm. Simultaneously or after bonding the second blade member to the first blade member, the wind turbine shell may be closed, preferably by joining the pressure side shell half to the suction side shell half.

[0025] Preferably, after closing of the wind turbine shell, an ultrasound image, preferably a cross-sectional image, of the bonded joint and at least a portion of the combined first and second blade members is obtained. In a preferred embodiment, the ultrasound image is obtained by ultrasonic scanning, preferably through the first blade member, and preferably through the bonded joint and through the second blade member. Preferably, the ultrasound image is obtained during an ultrasound scan over the outer blade surface at the area of ​​the bonded joint, such as at the area of ​​the bonded joint between the shell and the shear web, using an ultrasound probe, typically comprising an ultrasound transducer. The ultrasound probe may comprise one or more elements for transmitting and receiving ultrasound waves.

[0026] One or more ultrasound images of the bond joint and the adjacent first and second blade components may be obtained during an ultrasound scan, the ultrasound scan comprising moving an ultrasound probe along the outer surface of the wind turbine blade (e.g. along a scan line). One or more cross-sectional ultrasound images are thereby preferably obtained. The cross-sectional image(s) thus obtained advantageously comprises information about the integrity of the bond joint between the first blade component and the second blade component.

[0027] Therefore, in a preferred embodiment, the ultrasound image is a cross-sectional image obtained by moving the ultrasound probe along the scanning path along the outer blade surface. Preferably, the cross-sectional image is obtained by performing a B-scan. The B-scan image is preferably a vertical cross-sectional image of the relevant area containing the bonded joint, typically containing information about the probe position and depth. Therefore, the ultrasound scan will typically include obtaining data about the position of the ultrasound probe and depth data obtained by the probe, wherein the cross-sectional image can be created by correlating the data.

[0028] Preferably, during ultrasound scanning, echo amplitudes are obtained and stored digitally, usually along with transducer positions. The ultrasound images are preferably viewable on a connected screen, such as a portable computer device. In some embodiments, the cross-sectional ultrasound images are displayed in real time on a display device such as a monitor. In some embodiments, a handheld monitor may be used, or a wirelessly connected computer that can display the images.

[0029] In a preferred embodiment, the ultrasound image is a two-dimensional ultrasound image. In a preferred embodiment, the ultrasound image is an ultrasound B-scan image.

[0030] An ultrasound imaging marker is identified on the ultrasound image to verify the integrity of the bonded joint between the first blade member and the second blade member. Therefore, preferably, verifying the integrity of the bonded joint includes confirming the presence of the second blade member connected to the bonded joint. In a preferred embodiment, the step of identifying the ultrasound imaging marker on the ultrasound image includes visually observing a characteristic pattern of the ultrasound imaging marker on a cross-sectional ultrasound image (such as a B-scan image). The step of identifying the ultrasound imaging marker (preferably by observing the characteristic pattern) can be performed by an operator, or by using a computer device (preferably using an image analysis program for performing cross-sectional image analysis). In some embodiments, the step of identifying the ultrasound imaging marker (preferably by observing the characteristic pattern) may include detecting a signal whose echo level is greater than a predetermined threshold. The predetermined threshold may be an absolute value, or it may be determined relative to a background echo level. The step of visually observing the characteristic pattern of the ultrasound imaging marker on the ultrasound image may include visually confirming the presence of the characteristic pattern on the ultrasound image.

[0031] In a preferred embodiment, the characteristic pattern of the ultrasound imaging marker on the ultrasound image may include a characteristic shape, such as a characteristic two-dimensional shape on a cross-sectional ultrasound image. In another preferred embodiment, the characteristic pattern of the ultrasound imaging marker on the ultrasound image may include a characteristic signal intensity. In a particularly preferred embodiment, the characteristic pattern of the ultrasound imaging marker on the ultrasound image includes a combination of a characteristic shape (such as a characteristic two-dimensional shape on a cross-sectional ultrasound image) and a characteristic intensity.

[0032] In some embodiments, an operator or an image analysis program running on a computer device may compare a reference characteristic shape and / or a reference characteristic signal intensity stored on the computer device with a shape and / or a signal intensity detected on the ultrasound image to confirm the presence or absence of the ultrasound imaging marker on the ultrasound image. Preferably, the characteristic pattern of the ultrasound imaging marker includes an attenuated ultrasound echo, such as a scattered ultrasound echo, or an ultrasound echo having an intensity lower than that of an ultrasound wave generated by an ultrasound probe.

[0033] In some embodiments, identifying a characteristic pattern of an ultrasound imaging marker on an ultrasound image involves comparing two images including a first image showing a reference image without the marker and a second image with the marker.

[0034] In a preferred embodiment, the step of identifying ultrasound imaging markers on the ultrasound image further comprises visually observing a characteristic pattern at a predetermined location (such as within a predetermined depth interval) of the cross-sectional ultrasound image.

[0035] The ultrasound image may be a B-mode ultrasound image obtained by using a B-scan technique. The ultrasound probe may include an ultrasound transceiver, in which the reflected echo of the ultrasound wave is sensed. The ultrasound probe may be operated using a "pulse echo" method. Therefore, preferably, the ultrasound wave generated by the transceiver bounces off the ultrasound imaging marker and reflects. Therefore, in a preferred embodiment, ultrasound examination is performed using an ultrasound transceiver operating in a pulse echo mode.

[0036] In another aspect, the invention relates to a wind turbine blade comprising a first blade component and a second blade component joined to each other along at least one bonded joint, wherein the second blade component comprises an ultrasonic imaging marker permanently attached to the second blade component. Such a wind turbine blade differs structurally from known blades in that it comprises one or more ultrasonic imaging markers, typically located inside the blade, as a permanent part. This has the advantage that the integrity of the bonded joint can be effectively checked over the service life of the blade using the method of the invention.

[0037] In a preferred embodiment, the first blade component is a blade shell portion, and wherein the second blade component is a shear web, the shear web comprising at least one mounting flange for adhesively joining the shear web to a shear web mounting area on an inner surface of the blade shell portion, wherein the mounting flange comprises a first surface facing the shear web mounting area and an opposing second surface, wherein the ultrasonic imaging marker is attached to the opposing second surface of the mounting flange. The above-mentioned features and embodiments of the respective parts (such as the ultrasonic imaging marker) are equally applicable to the blade of this aspect of the invention.

[0038] In another aspect, the invention relates to a system for inspecting a wind turbine blade having a pair of shell portions surrounding a second blade component adhesively bonded to one or both of the shells, the system comprising: an ultrasound imaging marker attached to the second blade member, and An ultrasound machine for taking ultrasound images of an interior portion of a shell of a wind turbine blade including ultrasound imaging markers.

[0039] The ultrasound imaging marker is preferably attached to the blade member in the vicinity of the bond joint between the blade member and the shell.The above described features and embodiments of the various parts (such as the ultrasound imaging marker) are equally applicable to the system of this aspect of the invention.

[0040] In another aspect, the present invention relates to a method of inspecting a glued assembly of a first wind turbine blade component and a second wind turbine blade component, the method comprising obtaining an ultrasonic image of the glued assembly, comprising receiving an ultrasonic image of the glued assembly, preferably a cross-sectional ultrasonic image, such as a B-scan ultrasonic image, and identifying an ultrasonic imaging marker attached to the second wind turbine blade component on the ultrasonic image to verify the integrity of the bonded joint between the first blade component and the second blade component.

[0041] In a preferred embodiment, the first blade component is a blade shell portion, such as a suction side shell half or a pressure side shell half, and the second blade component is a shear web, wherein preferably a mounting flange of the shear web is bonded to the inner surface of the shell portion. The above-described features and embodiments of the respective parts (such as ultrasonic imaging markers) are equally applicable to the method of inspecting a glued assembly of this aspect of the invention.

[0042] The ultrasound machine used to obtain ultrasound images may include multiple phased array probes capable of generating cross-sectional images without mechanical scanning, or it may include a single element probe with a mechanical scanning mechanism.

[0043] In another aspect, the present invention relates to a method of manufacturing a wind turbine blade, comprising the steps of providing a first blade component and a second blade component; attaching at least one imaging marker to the second blade component; bonding the second blade component to the first blade component along at least one bond joint; obtaining an image of the bond joint and at least a portion of the bonded first and second blade components; and identifying the imaging marker on the image to verify the integrity of the bond joint between the first blade component and the second blade component.

[0044] The image is preferably obtained by non-invasive imaging techniques, such as radar, infrared thermography or X-ray imaging.

[0045] It should be appreciated that the term "adhesive" or "glue" as used herein encompasses any type of adhesive or bonding material that is preferably applied in an initially flowable state. Any suitable type of epoxy resin, compound or other material may be used in this regard.

[0046] It will be understood that any embodiments and features described above in relation to the method of manufacturing a wind turbine blade are equally applicable to the wind turbine blade, the system for inspecting a wind turbine blade and the method of inspecting a glued assembly, and vice versa.

[0047] As used herein, the term "longitudinal" means an axis or direction extending substantially parallel to the largest linear dimension of the element in question (eg, a wind turbine blade). BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The invention is explained in more detail below with reference to the embodiments shown in the accompanying drawings, in which: Figure 1 A wind turbine is shown, Figure 2 shows a schematic diagram of a wind turbine blade, Figure 3 A schematic diagram showing a cross section of a wind turbine blade, Figure 4 is a cross-sectional view of a glued assembly including a bonded joint between a shell portion and a shear web, Figure 5 is a cross-sectional view of a glued assembly showing a defective bonded joint between the shell section and the shear web, Figure 6 is an ultrasound image of a glued assembly with a bonded joint showing the posterior wall echo detected at a certain depth, Figure 7 is a cross-sectional view of a glued assembly having a bonded joint between a shell portion and a shear web marked using ultrasonic imaging according to one embodiment of the present invention, Figure 8 is a cross-sectional view of a glued assembly having a bonded joint between a shell portion and a shear web marked using ultrasonic imaging according to another embodiment of the present invention, and Fig. 9 is an ultrasound image of a glued assembly having a bonded joint showing a characteristic pattern created by ultrasound imaging markings in accordance with the present invention. DETAILED DESCRIPTION

[0049] Figure 1 A conventional modern upwind wind turbine according to the so-called "Danish concept" is shown, having a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor axis. The rotor comprises a hub 8 and three blades 10 extending radially from the hub 8, the blades each having a blade root 16 closest to the hub and a blade tip 14 farthest from the hub 8.

[0050] Figure 2 A schematic diagram of an embodiment of a wind turbine blade 10 according to the invention is shown. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 30 closest to the hub, a profile or airfoil region 34 furthest from the hub, and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10 when the blade is mounted on the hub, and a trailing edge 20 facing in the opposite direction of the leading edge 18.

[0051] The airfoil region 34 (also referred to as the profile region) has an ideal or almost ideal blade shape with respect to generating lift, while the root region 30 has a substantially circular or elliptical cross section for structural considerations, for example, which makes it easier and safer to mount the blade 10 to the hub. The diameter (or chord) of the root region 30 can be constant along the entire root region 30. The transition region 32 has a transition profile that gradually changes from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 generally increases with increasing distance r from the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

[0052] The shoulder 40 of the blade 10 is defined as the location where the blade 10 has its maximum chord length. The shoulder 40 is generally provided at the boundary between the transition region 32 and the airfoil region 34. It should be noted that the chords of the different sections of the blade generally do not lie in a common plane, because the blade may be twisted and / or curved (i.e. pre-bent), thus providing the chord plane with a corresponding twisted and / or curved course, which is to compensate for the most common case of the local velocity of the blade depending on the radius from the hub.

[0053] Figure 3 A schematic diagram of a cross section of a blade is shown. As previously mentioned, the blade 10 comprises a pressure side shell portion 36 and a suction side shell portion 38. The pressure side shell portion 36 comprises a spar cap 41, also referred to as a main laminate, which constitutes the load-bearing portion of the pressure side shell portion 36. The spar cap 41 comprises a plurality of fiber layers 42, which mainly comprise unidirectional fibers aligned in the longitudinal direction of the blade so as to provide stiffness to the blade. The suction side shell portion 38 further comprises a spar cap 45, which comprises a plurality of fiber layers 46. The spar cap 45 has a leading edge side 61, which is closer to the leading edge than the opposite trailing edge side 63 of the spar cap 45. The pressure side shell portion 36 may also comprise a core material 43, which is typically made of balsa wood or foamed polymer and is sandwiched between several fiber reinforced skin layers. The core material 43 is used to provide stiffness to the shell so as to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell portion 38 may also comprise a core material 47.

[0054] The spar caps 41 of the pressure side shell portion 36 and the spar caps 45 of the suction side shell portion 38 are connected via a first shear web 50 and a second shear web 55. In the illustrated embodiment, the shear webs 50, 55 are formed as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web foot flanges. The shear web body comprises a core material 51, such as balsa wood or foamed polymer, covered by several skin layers 52 made of several fiber layers. The blade shells 36, 38 may comprise other fiber reinforcements at the leading and trailing edges. Typically, the shell portions 36, 38 are bonded to each other via glued flanges.

[0055] Figure 4 is a cross-sectional view of the glued assembly 100, which includes the bonded joint 72 between the shell portion 36 and the shear web 50, both of which are as described above with reference to Figure 3 The general type discussed. Figure 4 An ultrasonic probe 81 (e.g., a handheld ultrasonic transceiver) is used to obtain an ultrasonic image of the region of the bonded joint, where incoming ultrasonic waves 82 may be reflected and where reflected waves 84 are detected by the ultrasonic probe 81. In the example shown, the surface 78 of the mounting flange 76 of the shear web 50 may produce a back wall echo.

[0056] Figure 6 A possible ultrasound image 74 is shown in FIG. 8 , wherein the area highlighted by the black frame 86 corresponds to the posterior wall echo signal. Figure 6 The x-axis 87 represents the position of the ultrasonic probe along the scan line on the outer blade surface, and Figure 6 The y-axis 85 of the diagram represents the depth at each location. The ultrasonic signal is generated by the reflection of the ultrasonic waves emitted by the ultrasonic probe, which is displayed in different tones depending on the intensity. By using the depth gauge 85, the depth of the back wall echo can be determined, which can allow inferences about the presence of the shear web and therefore the integrity of the adhesive joint of the glued assembly 100.

[0057] However, it is challenging to precisely control the thickness of the bonded joint 72 and there is usually a certain tolerance, which may be on the order of several millimeters, such as 1-25 mm. Similarly, the mounting flange 76 of the shear web 50 may have a thickness on the order of several millimeters. This means that Figure 6 The ultrasound image 74 may correspond exactly to Figure 5 , which shows a defective bonded joint between the shell portion 36 and the shear web 50. Here, the shear web 50 is separated from the shell portion 36 due to the bonding defect. Moreover, the thickness t2 of the bonded joint 72 is slightly higher than Figure 4 The thickness t1 of the bonded joint 72 is shown in FIG. Figure 6The back wall echo signal 86 shown in FIG. 8 may well correspond to the back wall of the bond joint 72 rather than the back wall created by the shear web mounting flange 76. Therefore, the same ultrasonic signal measured at the same profile depth may be ambiguous and the integrity of the bond joint may not be verified using this technique.

[0058] Therefore, in the method for manufacturing a wind turbine blade according to the present invention, if Figure 7 and Figure 8 As shown in FIG. 5 , at least one ultrasound imaging marker 70 is attached to the second blade member 50. Figure 7 In the embodiment shown in FIG. 1 , the shear web 50 includes at least one mounting flange 76 for adhesively joining the shear web to a shear web mounting area 80 on the inner surface of the blade shell portion, wherein the mounting flange includes a first surface 77 and an opposing second surface 78, wherein the first surface 77 is bonded to the shear web mounting area 80, and wherein the ultrasonic imaging marker 70 is attached to the second surface 78 of the mounting flange. The ultrasonic imaging marker 70 is preferably adhesively bonded to the surface 78 of the shear web 50.

[0059] Figure 7 The ultrasound imaging marker 70 in the embodiment can be made of a polymer foam material capable of absorbing and / or scattering ultrasound waves, such as PET foam. The ultrasound imaging marker 70 is shaped as a hemisphere or dome in the example shown, and is preferably relatively light and small, with a preferred diameter 73 of 5-25 mm. Therefore, Figure 7 The ultrasound imaging marker 70 includes a dome-shaped surface 71 .

[0060] The second blade component (ie, the shear web 50 of the illustrated embodiment) is then bonded to the first blade component (ie, the shell portion 36) along the bond joint 72 using a suitable bonding paste or adhesive.

[0061] An ultrasound probe 81 , which may be a handheld ultrasound transceiver, may be used to obtain an ultrasound image 74 of the bond joint 72 and at least a portion of the joined first and second blade components.

[0062] exist Figure 8 In the embodiment shown in , an ultrasonic imaging marker 70 is integrally incorporated into the second blade member 50. Here, the marker 70 has an arcuate end surface 71 that points toward the shell portion 36 and is capable of scattering ultrasonic waves to produce an identifiable ultrasonic signature 88.

[0063] Fig. 9 A representative ultrasound image 74 is shown, which is a two-dimensional cross-sectional image. Fig. 9 The x-axis 87 represents the position of the ultrasonic probe along the scan line on the outer blade surface, and Fig. 9The y-axis 85 of FIG. 8 represents the depth at each position. Again, the ultrasound signal is generated by the reflection of the ultrasound wave emitted by the ultrasound probe, which is displayed in different tones depending on the intensity. Fig. 9 As can be seen in FIG. 1 , the ultrasonic imaging marker 70 will change the resulting ultrasonic image compared to the known techniques discussed above. The step of identifying the ultrasonic imaging marker 70 on the ultrasonic image 74 may preferably include visually observing a characteristic pattern 88 created by the ultrasonic imaging marker 70 at a predetermined position of the two-dimensional ultrasonic image. Thus, the resulting ultrasonic image can be used to verify the integrity of the bonded joint 72 between the first blade component and the second blade component. A wind turbine blade produced according to the method of the present invention will typically include an ultrasonic imaging marker 70 permanently attached to the second blade component 50.

[0064] The invention is not limited to the embodiments described herein and may be varied or modified without departing from the scope of the invention.

[0065] Reference Mark List 2. Wind Turbines 4 Tower 6. Cabin 8 Hub 10 blades 14 Leaf tip 16 Blade root 18 Leading Edge 20 trailing edge 22 Pitch axis 30 Root Zone 32 Transition Zone 34 Airfoil area 36 Pressure side shell 38 Suction side shell 40 Shoulder / Maximum Chord Location 41 Spar cap 42 Fiber Layer 43 Sandwich material 45 Spar cap 46 Fiber Layer 47 Sandwich material 50 First shear web 51 core parts 52 Skin layer 55 Second shear web 56 Core material of the second shear web 57 Skin layer of the second shear web 60 Filling rope 62 Shell surface 64 Inner shell surface 70 Ultrasound imaging markers 71 Arched Surface 72 Bonded joints 73 Diameter 74 Ultrasound images 76 Mounting flange 77 First surface of mounting flange 78 Second surface of mounting flange 80 Shear web installation area 81 Ultrasound probe 82 Ultrasound 84 Reflected Ultrasonic Wave 85 Depth Ruler 86 Back wall echo 87x Axis / Scanner Position L Blade length r local radius, radial distance from the blade root

Claims

1. A method for manufacturing a wind turbine blade (10), comprising the following steps providing a first blade member (36) and a second blade member (50), attaching at least one ultrasound imaging marker (70) to the second blade member (50), bonding the second blade member (50) to the first blade member (36) along at least one bonded joint (72), obtaining an ultrasound image (74) of the bonded joint (72) and at least a portion of the joined first and second blade members, and An ultrasound imaging marker (70) is identified on the ultrasound image to verify the integrity of the bonded joint (72) between the first blade component and the second blade component.

2. The method of claim 1, wherein the first blade component (36) is a blade shell portion, and wherein the second blade component (50) is a shear web.

3. The method according to claim 2, wherein the shear web (50) includes at least one mounting flange (76) for adhesively joining the shear web to a shear web mounting area (80) on the inner surface of the blade shell portion, wherein the mounting flange includes a first surface (77) and an opposing second surface (78), wherein the first surface (77) is bonded to the shear web mounting area (80), and wherein the ultrasonic imaging marker (70) is attached to the second surface (78) of the mounting flange.

4. The method according to any of the preceding claims, wherein the ultrasound image (74) is a two-dimensional ultrasound image, preferably a cross-sectional ultrasound image, such as an ultrasound B-scan image.

5. The method of claim 4, wherein the step of identifying the ultrasound imaging marker (70) on the ultrasound image (74) comprises visually observing a characteristic pattern created by the ultrasound imaging marker (70) at a predetermined location on the two-dimensional ultrasound image.

6. The method according to any of the preceding claims, wherein the ultrasound imaging marker (70) is capable of absorbing ultrasound waves.

7. The method according to any of the preceding claims, wherein the ultrasound imaging marker (70) is capable of scattering ultrasound waves.

8. The method according to any of the preceding claims, wherein the ultrasound imaging marker (70) comprises a polymer foam material, preferably polyethylene terephthalate (PET) foam.

9. The method according to any of the preceding claims, wherein the ultrasound imaging marker (70) has a diameter (73) or maximum dimension of 5-25 mm.

10. The method according to any of the preceding claims, wherein the ultrasound imaging marker (70) comprises at least one arcuate surface (71).

11. The method according to any of the preceding claims, wherein the step of attaching at least one ultrasound imaging marker (70) to the second blade member (50) comprises adhesively bonding the ultrasound imaging marker (70) to an outer surface of the second blade member (50).

12. The method according to any one of claims 1 to 10, wherein the step of attaching at least one ultrasound imaging marker (70) to the second blade member (50) comprises integrally incorporating the ultrasound imaging marker (70) into the second blade member (50).

13. A wind turbine blade comprising a first blade component (36) and a second blade component (50) bonded to each other along at least one bond joint (72), wherein the second blade component (50) comprises an ultrasonic imaging marker (70) permanently attached to the second blade component (50).

14. A wind turbine blade according to claim 13, wherein the first blade component (36) is a blade shell portion, and wherein the second blade component (50) is a shear web, wherein the shear web includes at least one mounting flange (76) for adhesively joining the shear web to a shear web mounting area on an inner surface of the blade shell portion, wherein the mounting flange includes a first surface (77) and an opposing second surface (78), wherein the first surface is bonded to the shear web mounting area, and wherein the ultrasonic imaging marker (70) is attached to the second surface (78) of the mounting flange.

15. A method of inspecting a glued assembly (100) of a first wind turbine blade component and a second wind turbine blade component, the method comprising obtaining an ultrasound image (74) of the glued assembly, which includes receiving a cross-sectional ultrasound image, such as a B-scan ultrasound image, of the glued assembly, and An ultrasonic imaging marker (70) attached to the second wind turbine blade component is identified on the ultrasonic image to verify the integrity of a bonded joint (72) between the first blade component and the second blade component.

Images