Abstract:
The present application thus provides a method of inspecting composite turbine blade spar caps during lay up. The method may include the steps of applying a layer to a mold, measuring a surface characteristic of the layer with a profilometer, and determining if the layer has an out of plane wave therein based on the measured surface characteristic.

Description:
TECHNICAL FIELD 
       [0001]    The present application and the resultant patent relate generally to wind turbine blades and inspection systems therefore and more particularly relate to a profilometry inspection system for a spar cap of a composite wind turbine blade to detect out of plane waves during manufacturing. 
       BACKGROUND OF THE INVENTION 
       [0002]    Modern wind turbine blades generally combine low weight and low rotational inertia with high rigidity and high resistance to fatigue and wear so as to withstand the various forces in the extreme conditions encountered over a typical life cycle. Generally described, a typical wind turbine blade may be constructed of layers of a composite material outer skin supported by a primary spar. Each layer of the composite material outer skin should be applied in a substantially uniform fashion to ensure that the turbine blade will meet performance and lifetime requirements. Out of plane waves or other types of non-uniformities in the application or the lay up process, however, may reduce the load carrying capacity of the structure and eventually may lead to failure in the field. This may be particularly true with respect to the manufacture of the spar cap and other types of components. 
         [0003]    Current methods for the inspection of assembled, cured turbine blade components include visual inspection and various types of non-destructive imaging inspection techniques such as ultrasonic testing. Such ultrasonic testing, however, may have limited use given the highly attenuative material of the outer skin. Computed tomography techniques also may be available but such testing may be time consuming and costly as well as presenting radiation safety concerns. 
       SUMMARY OF THE INVENTION 
       [0004]    The present application and the resultant patent thus provide a method of inspecting composite turbine blade spar caps during lay up. The method may include the steps of applying a layer to a mold, measuring a surface characteristic of the layer with a profilometer, and determining if the layer has an out of plane wave therein based on the measured surface characteristic. 
         [0005]    The present application and the resulting patent further provide a turbine blade spar cap profilometry inspection system. The turbine blade spar cap profilometry inspection system may include a spar cap mold, a composite material applicator positioned about the spar cap mold, and a profilometer positioned about spar cap mold. The profilometer determines a thickness of each layer applied to the spar cap mold by the composite material applicator so as to detect a layer with an out of plane wave. 
         [0006]    The present application and the resultant patent further provide a method of inspecting composite material turbine blade components. The method may include the steps of applying a composite material layer to a mold, measuring a surface characteristic of the composite material layer with a profilometer, creating a three dimensional surface map of the composite material layer, and determining if the composite material layer has an out of plane wave therein. 
         [0007]    These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic diagram of an exemplary wind turbine blade. 
           [0009]      FIG. 2  is a side sectional view of a portion of the wind turbine blade of  FIG. 1 . 
           [0010]      FIG. 3  is a schematic diagram of a wind turbine blade profilometry inspection system as may be described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring now to the drawings, in which like numerals refer to like elements throughout the several views,  FIG. 1  and  FIG. 2  show an example of a wind turbine blade  100  as may be described herein. The wind turbine blade may extend from a tip  110  to an opposing root  120 . Extending between the tip  110  and the root  120  may be a spar cap  130  and a shear web  140 . The shear web  140  may serve as the main structural support element within the wind turbine blade  100 . The spar cap  130  may be a composite portion running the length of the wind turbine blade  100  coincident with the shear web  140  so as to accommodate the overall tensile load on the wind turbine blade  100  when in use. The wind turbine blade  100  and the components thereof may have any suitable size, shape, or configuration. Other components and other configurations also may be used herein. 
         [0012]    The wind turbine blade  100  may be formed in a pair of shells. For example, a first shell  150  may extend from a first shell leading edge  160  to a first shell trailing edge  170  and may define a suction surface  180 . The first shell  150  may be bonded to a second shell  190 . The second shell  190  may extend from a second shell leading edge  200  to a second shell trailing edge  210  and may define a pressure surface  220 . Each shell  150 ,  190  may have areas that include a fiber reinforced material  230  and other areas that include a core material  240 . The fiber reinforced materials  110  may include E-glass fiber or a carbon fiber bonded with a composite resin. Other potential composite materials include graphite, boron, aramid, and other organic materials and hybrid fiber mixes that can form reinforcing fibers. The reinforcing fibers may be in the form of a continuous strand mat, woven, or unidirectional mat. The core materials  240  may include foam, balsawood, engineered core materials, and the like. Other types of materials may be used herein. 
         [0013]    The shells  150 ,  190  may be applied as multiple thin layers  260  in the form of a fiber resin matrix. The matrix holds the fibers in place and, under an applied load, deforms and distributes stresses to the fibers. The composite layers  260  may be formed into laminated or sandwich structures. Laminated structures include successive layers of composite materials bonded together. Sandwich structures may include a low density core between the layers of composite materials. Any number of the layers  260  may be used herein. 
         [0014]    Likewise, the individual components of the wind turbine blade  100  also made in individual molds. For the example, the lay up of the spar cap  130  may be done in a spar cap mold  300  and the like. As described above, any number the layers  260  may be applied in an automated or manual method to produce the spar cap  130  and other types of components. 
         [0015]    A defect  250  in one or more of the layer  260  may have an impact on the overall operation and lifetime of the components such as the spar cap  130  and the like. The defect  250  may include, for example, an out of plane wave  270  in one or more of the layers  260 . As described above, the out of plane wave  270  may reduce the overall load carrying capacity of the wind turbine blade  100  and the components thereof and eventually may lead to failure in the field. 
         [0016]    The components of the wind turbine blade  100  thus may be inspected via a wind turbine blade profilometry inspection system  280  as may be described herein. The wind turbine blade profilometry inspection system  280  may be a type of non-destructive testing using a profilometer  290  to accurately measure surface characteristics of the layers  260  of the components such as the spar cap  130 . A profilometer  290  is an optical device used to measure height variations on a surface with great precision. From these height differences, a three-dimensional surface map may be created. Specifically, the profilometer  290  may use the wave properties of light to compare an optical path between a test surface and a reference surface. An example of a profilometer suitable for use herein include the profile sensors offered by LMI Technologies of Vancouver, Canada under the “Gocator®” mark. Other types of three-dimensional sensors may be used herein. Other components and other configurations may be used herein. 
         [0017]    As is shown in  FIG. 3 , the wind turbine blade profilometry inspection system  280  may be positioned adjacent to the mold  300  used for the lay up of the components such as the spar cap  130  via a composite material applicator  310  and the like. Alternatively, a manual process also may be used. The profilometer  290  may be positioned adjacent to the mold  300 . The mold  300  thus acts as the reference surface for the profilometer  290 . The profilometer  290  may scan each layer  260  as applied during the lay up process and measure the changes in thickness. The resolution of the profilometer may be about 0.01 to about 0.06 millimeters to measure displacements of about one tenth of a ply thickness. Other types of resolution may be used herein. The profilometer  290  may detect an out of plane wave  270  in a layer  260  and provide an alert when such a wave may be detected so as to stop the lay up process. In addition to the lay up location, the profilometer  290  may be positioned about the layers  260  during curing so as to ensure also that no out of plane displacement occurred after the lay up process. 
         [0018]    The wind turbine blade profilometry inspection system  280  thus may provide fast and efficient inspection of turbine components such as the spar cap  130  during the lay up process and/or during the curing process. The system  280  may monitor changes and component thickness as each layer  260  is added. The system  280  thus may prevent the costly rejection of fully cured turbine blade components. Moreover, the robust system  280  described herein may lead to a reduced risk of field failure. Although the wind turbine blade profilometry inspection station  280  has been discussed in the context of the wind turbine components such as the spar cap  130 , other types of composite material surfaces, structures, and the like also may be inspected herein. 
         [0019]    It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.