Patent Publication Number: US-2015071701-A1

Title: Insert and Method of Attaching Insert to Structure

Description:
BACKGROUND 
     1. Field 
     Example embodiments relate to an insert and a method of attaching the insert to a structure. 
     2. Description of the Related Art 
     In the wind turbine industry, T-bolts are often used to attach a wind turbine blade to a hub.  FIGS. 1A and 1B  are views of a conventional T-bolt  10 . As shown in  FIGS. 1A and 1B , the conventional T-bolt  10  includes a threaded stud  2  having threads  4  at a first end thereof and a cross-nut  5  having a threaded hole  7 . In the prior art, the hole  7  may be sized to receive the threaded end of the stud  2  so that the threads  4  of the stud  2  engage the threads of the hole  7 . The threads of the stud  2  and the cross-nut  5  may be engaged with one another simply by rotating the stud  2  with respect to the cross-nut  5  as is well known in the art. 
       FIG. 1C  is a partial cross-section view of a wind turbine blade  50  illustrating a T-bolt arranged in a root  20  thereof. In the prior art, the T-bolt may be installed by drilling a first hole through material of the root  20  from an outside surface SO of the root  20  through to an inside SI of the root  20 . Alternatively, a first hole may be drilled from an inside surface SI to an outside surface SO. The first hole may or may not be drilled completely through the thickness of the root  20 . A second hole may then be drilled in a face F of the wind turbine blade root  20  to expose the first hole. The cross-nut  5  may then be inserted into the first hole. The stud  2  may then be inserted into the second hole and pushed through the second hole until the threads  4  of the stud  2  bear up against the threads of the hole  7 . The stud  2  may then be rotated to advance the threads  4  of the stud  2  into the hole  7  of the cross-nut  5  thus securing the stud  2  to the cross-nut  5 . In  FIG. 1C , the stud  2  has a second threaded end with second threads  4 ′ that enable the stud  2  to attach to a nut  95  thus allowing a secondary structure  90 , for example, a hub or a bearing of a wind turbine, to be connected to the wind turbine blade  50  as shown in  FIG. 1D . 
     As an alternative to T-bolts, some artisans have used inserts as a means for attaching a wind turbine blade to a wind turbine hub. For example, in WO 20111035548A1 a plurality of inserts is attached to a root of a wind turbine blade during a lamination process and a plurality of studs is used to connect the wind turbine blade to a hub using the plurality of inserts. Other artisans have turned to metal inserts as part of an assembly system. The metal inserts are often bonded into fiber-reinforced plastic composite structures, for example, a root of a wind turbine blade. A common method of fabrication is to drill a hole in the composite structure, position the insert in the hole using a fixture, and inject the adhesive into the hole around the insert through either a secondary hole drilled into the first hole or through the gap in the face of the structure. Another method of fabrication is to drill a hole in the composite structure, apply the adhesive to the outer surface of the metal insert and/or the inside of the hole, and position the insert in the hole using a fixture. In the aforementioned methods an artisan may assist the application and/or cure of the adhesive by sealing the open end of the first hole in the structure. 
     SUMMARY 
     The inventor has noticed several problems associated with conventional methods for attaching a wind turbine blade to a wind turbine hub. Such problems are also suffered in other industries and, as such, are not limited to the wind turbine industry. For example, when T-bolts are used, relatively large compressive stresses may be present in the root near the cross-nuts of the T-bolts. These stresses may lead to failure, for example by cleaving of fibers near the cross-nuts. To alleviate this problem, a larger diameter cross-nut may be used, but this increases the perforations of the root which may result in increased warping in the cross-nut holes and/or root cylinder when the structure is subjected to loads. With regard to laminating inserts in place, this process results in a root having voids created near the inserts which act as stress concentrators leading to delamination near the inserts. With regard to bonding metal inserts, it is extremely challenging to ensure thorough fill of the space around the insert without macroscopic voids created by trapped air. Macroscopic voids are to be distinguished from microscopic voids due to air entrained into the adhesive due to the mixing process, the latter being accounted in the nominal properties of the adhesive. Macroscopic voids create stress concentrations when the structure and insert are subjected to loads. The method has a second short-coming in that it can be challenging to fixture the insert concentrically in the hole to ensure a uniform bond thickness. Nonuniform bond thickness can also create stress concentrations. Stress concentrations can cause premature failure of the part. 
     With the above in mind, the inventor has set out to design a method which may be used to embed an insert, for example, a female-threaded insert, into a structure, for example, a composite structure, that does not suffer the aforementioned problems. As a result, the inventor has developed a novel and nonobvious insert, system, and method for bonding an insert, for example, a female-threaded metal insert, into a composite structure. Such a method is useful in various industries. For example, the novel method may be used to connect a wind turbine blade to a hub of a wind turbine. Application to the wind turbine industry and wind turbine structures is not intended to be a limiting feature of the invention since the invention may be applied to a variety of industries and/or structures. For example, other applications include, but are not limited to, the aerospace, automobile, construction, and/or boating industries or any industry where it is desired to bond an insert into a structure. 
     Example embodiments of the invention include an insert. In example embodiments the insert may be placed in a cavity formed in a structure, for example, a composite structure. In example embodiments, various sealing members may be provided to make the hole an airtight chamber. In example embodiments, a vacuum may be applied to the hole to remove air therefrom. Under vacuum, an adhesive may be applied inside the cavity to bond the insert therein. Because the adhesive is applied under a vacuum, macroscopic voids in the adhesive may be eliminated thereby leading to a bond having a relatively long service life in comparison to the conventional art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments are described in detail below with reference to the attached drawing figures, wherein: 
         FIG. 1A  is a view of a T-bolt in accordance with the prior art; 
         FIG. 1B  is an exploded view of the T-bolt in accordance with the prior art; 
         FIG. 1C  is a partial cross-section of a wind turbine blade root with a T-bolt therein in accordance with the prior art; 
         FIG. 1D  is a partial cross-section of a wind turbine blade root attached to a second structure in accordance with the prior art; 
         FIG. 2A  is a front view of an assembly accordance with example embodiments; 
         FIG. 2B  is a side view of the assembly in accordance with example embodiments; 
         FIG. 2C  is a cross-section view of the assembly in accordance with example embodiments; 
         FIG. 2D  is a cross-section view of an assembly in accordance with example embodiments 
         FIG. 3A  is a front view of an insert in accordance with example embodiments; 
         FIG. 3B  is a side view of the insert in accordance with example embodiments; 
         FIG. 3C  is a cross-section view of the insert in accordance with example embodiments; 
         FIG. 3D  is a cross-section view of an insert in accordance with example embodiments; 
         FIG. 4A  is a front view of a sealing member in accordance with example embodiments; 
         FIG. 4B  is a side view of the sealing member in accordance with example embodiments; 
         FIG. 5A  is a side view of an applicator unit in accordance with example embodiments; 
         FIG. 5B  is a perspective view of an applicator unit in accordance with example embodiments; 
         FIGS. 6A-6C  illustrate example assembly steps for forming the assembly in accordance with example embodiments; 
         FIGS. 6D and 6E  illustrate examples of assemblies in accordance with example embodiments; 
         FIG. 7A  illustrates a partial section view of a structure in accordance with example embodiments; 
         FIG. 7B  illustrates the structure having a cavity in accordance with example embodiments; and 
         FIGS. 8A-8B  illustrate an assembly being inserted into the cavity in the structure in accordance with example embodiments; 
         FIG. 8C  illustrates a vacuum system and an adhesive supply unit attached to the assembly inserted into the cavity of the structure in accordance with example embodiments; 
         FIGS. 8D-8I  illustrate an adhesive filling a space between the insert and the structure to bond the insert to the structure in accordance with example embodiments; 
         FIG. 8J  illustrates tubes of the assembly in a cut configuration in accordance with example embodiments; 
         FIGS. 9A and 9B  illustrate a stud being attached to an insert bonded to a structure in accordance with example embodiments; 
         FIGS. 10A-10D  illustrate operations of bolting a second structure to a first structure using the inserts and studs according to example embodiments; 
         FIG. 11  illustrates a root of a wind turbine blade with a plurality of inserts in accordance with example embodiments; 
         FIGS. 12A-12C  illustrate an assembly in accordance with example embodiments; 
         FIGS. 13A-13C  illustrate an assembly in accordance with example embodiments; 
         FIGS. 14A-14C  illustrate assemblies with spacers in accordance with example embodiments; 
         FIGS. 15A-15B  illustrate an assembly in accordance with example embodiments; 
         FIGS. 16A-16D  are views of an assembly in accordance with example embodiments; and 
         FIGS. 17A-17D  illustrate an operation of inserting and bonding an insert to a structure. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings, in which example embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the sizes of components may be exaggerated for clarity. 
     In this application, it is understood that when an element or layer is referred to as being “on,” “attached to,” “connected to,” or “coupled to” another element or layer, it can be directly on, directly attached to, directly connected to, or directly coupled to the other element or layer or intervening elements that may be present. In contrast, when an element is referred to as being “directly on,” “directly attached to,” “directly connected to,” or “directly coupled to” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     In this application it is understood that, although the terms first, second, etc. may be used herein to describe various elements and/or components, these elements and/or components should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section. Thus, a first element, component region, layer or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the structure in use or operation in addition to the orientation depicted in the figures. For example, if the structure in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The structure may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     Embodiments described herein will refer to planform views and/or cross-sectional views by way of ideal schematic views. Accordingly, the views may be modified depending on manufacturing technologies and/or tolerances. Therefore, example embodiments are not limited to those shown in the views, but include modifications in configurations formed on the basis of manufacturing process. Therefore, regions exemplified in the figures have schematic properties and shapes of regions shown in the figures, and do not limit example embodiments. 
     The subject matter of example embodiments, as disclosed herein, is described with specificity to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different features or combinations of features similar to the ones described in this document, in conjunction with other technologies. Generally, example embodiments relate to an insert and a method for attaching the insert to a structure. 
       FIG. 2A  is a front view of an assembly  1000  in accordance with example embodiments,  FIG. 2B  is a side view of the assembly  1000  in accordance with example embodiments, and  FIG. 2C  is a cross-section view of the assembly  1000  in accordance with example embodiments. Referring to  FIGS. 2A-2C , the assembly  1000  may be comprised of an insert  100 , a sealing member  200 , and an applicator unit  300 . As shown in  FIGS. 2A-2C , the sealing member  200  may be arranged on an outside of the insert  100  and the applicator unit  300  may be enclosed, at least partially, by the insert  100 . 
       FIG. 3A  is a front view of the insert  100  in accordance with example embodiments,  FIG. 3B  is a side view of the insert  100  in accordance with example embodiments, and  FIG. 3C  is a cross-section view of the insert  100  in accordance with example embodiments. Referring to  FIGS. 3A-3C , the insert  100  may include a cylindrical body  120  with a flange  110  at one end thereof. In example embodiments, the flange  110  may resemble an annular disk having an inner diameter of D1, an outer diameter of D3, and a thickness t1. Although the flange  110  is illustrated as resembling an annular disk, example embodiments are not limited thereto as the flange  110  may resemble another shape such as, but not limited to, a square or rectangular plate having a circular hole having the diameter D1. 
     In example embodiments, the cylindrical body  120  may resemble a substantially hollow cylinder having a length L1, an inner diameter D1, and an outer diameter D2. In example embodiments, an internal surface of the cylindrical body  120  may be threaded as shown in  FIG. 3C . In example embodiments, the threads  122  of the cylindrical body  120  may be configured to engage threads of a stud (as will be explained later). In example embodiments, the outer diameter D2 of the cylindrical body  120  may be smaller than the outer diameter D3 of the flange  110  and the flange  110  may thus serve as a structure upon which the sealing member  200  may bear. In example embodiments, the threads  122  may extend along a discrete length of the internal surface of the body  120  (as shown in  FIG. 3C ) or along the entire length of the body  120 . Thus, the position and length of the threads  122  illustrated in the figures is not intended to limit the invention. 
       FIGS. 4A and 4B  are views of the sealing member  200  in accordance with example embodiments. In example embodiments, the sealing member  200  may resemble an o-ring having an inner diameter of D4 and an outer diameter of D5. In example embodiments, the inner diameter D4 may be about the same size as the outer diameter D2 of the cylindrical body  120 . In example embodiments, the sealing member  200  may be made of a flexible material, for example, rubber or plastic, and thus may be stretched. In the event the sealing member  200  is made of a flexible material, the sealing member  200  may stretch somewhat. Thus, in example embodiments, the inner diameter D4 of the sealing member  200 , in an unstressed state, may be smaller than the outer diameter D2 of the cylindrical body  120 . Example embodiments, however, are not limited thereto as the inner diameter D4 of the sealing member  200  may be about the same size as, or larger than, the outer diameter D2 of the cylindrical body  120 . In some views the sealing member  200  is illustrated as having a circular cross section. This, however, is not meant to be a limiting feature since a cross section of the sealing member  200  may have a different shape such as, but not limited to, a square or rectangular shape. 
       FIGS. 5A and 5B  are views of the applicator unit  300  in accordance with example embodiments. In example embodiments, the applicator unit  300  may include a body  310  and first and second tubes  320  and  330  that penetrate the body  310 . In example embodiments the body  310  may be made of a flexible material such as, but not limited to, rubber or a cork type material. In example embodiments, the body  310  may resemble a partial cone having a first diameter D6 and a second diameter D7 which may be about the same size as, or smaller than the first diameter D6. In example embodiments, the second diameter D7 may be smaller than the inner diameter D1 of the cylindrical body  120  and the first diameter D6 may be larger than the inner diameter D1 of the cylindrical body  120 . As a consequence, the body  310  may be partially inserted into the cylindrical body  120  with application of little to no force. In example embodiments, because the body  310  may be made of a flexible material, the body  310  may be pushed into the cylindrical body  120  thereby reducing the first diameter D6 to that of the inner diameter D1 of the cylindrical body  120 . In doing so, the body  310  may create a seal in the cylindrical body  120 . In this particular nonlimiting example, the seal is created at an end of the cylindrical body  120 . 
       FIGS. 6A-6C  illustrate operations of assembling the assembly  1000 . As shown in  FIG. 6A , the sealing member  200  may moved along the cylindrical body  120  until it reaches the flange  110  as shown in  FIG. 6B . Then, the applicator unit  300  may be pushed into the second end of the cylindrical body  120  as shown in  FIG. 6B  until the second end of the cylindrical body  120  is sealed as shown in  FIG. 6C . In example embodiments, the first and second tubes  310  and  320  may be exposed at a first end of the cylindrical body  120  and at the second end of the cylindrical body  120 . The order of assembly is relatively unimportant. For example, in  FIGS. 6A-6C  it is illustrated that the sealing member  200  is placed on the cylindrical body  120  before the applicator unit  300  is installed. However, in example embodiments, the applicator unit  300  may be installed before the sealing unit  200  is moved along the cylindrical body  120 . 
     The embodiment of  FIGS. 2A-2C  is not intended to limit the invention. For example,  FIG. 2D  shows a cross-section of a similar assembly  1000 M. In example embodiments, the assembly  1000 M may be substantially identical to the assembly  1000 . For example, the assembly  1000 M may have a sealing member  200 M and an applicator unit  300 M which may be substantially identical to the earlier described sealing member  200  and applicator unit  300 . Furthermore, the assembly  1000 M may include an insert  100 M which is substantially similar to the insert  100 . However, in  FIG. 2D , the insert  100 M only has threads  122 M running along a portion of cylindrical body  120 M. All other aspects of the assembly  1000  and  1000 M may be identical. A benefit of the assembly  1000 M, however, is that it allows for the pretensioning of a stud if such pretensioning is desired.  FIG. 3D  illustrates a cross-section of the insert  100 M clearly showing a lack of threads near an opening of the insert  100 M near a face of the flange  110 M of the insert  100 M. 
       FIG. 7A  illustrates a structure  2000  and  FIG. 7B  illustrates the structure  2000  with a cavity  2100  formed therein. In example embodiments, the structure  2000  may be, but is not limited to, a root of a wind turbine blade. The structure  2000 , however, may be something other than a wind turbine blade. For example, the structure  2000  may be a panel of an automobile or an airplane wing or any other structure that has a cavity formed therein. In example embodiments the structure  2000  may be a composite material, however, the invention is not limited thereto. For example, the structure  2000  may be made from another material such as, but not limited to, a metal or a ceramic. In example embodiments, the cavity  2100  may be formed therein by a conventional method such as, but not limited to, a boring method, a drilling method, a pressing method, a punching method, a printing method, or a casting process. In example embodiments, the cavity  2100  may have a depth L2 and a diameter D8. In example embodiments, the depth L2 should be longer that the length L1 of the cylindrical body  120  (see  FIG. 3B ) and the diameter D8 should be larger than the outer diameter D2 of the cylindrical body  120  but smaller than the outer diameter D5 of the sealing member  200 . 
       FIGS. 8A and 8B  illustrate a portion of the assembly  1000  being inserted into the cavity  2100  formed in the structure  2000 . In example embodiments, the cylindrical body  120  of the insert  100  may be inserted into the cavity  2100  until the sealing member  200  contacts the structure  2000  as shown in  FIG. 8B . 
     In example embodiments, the first tube  320  may be attached to a vacuum system  3000  and the second tube  330  may be attached to an adhesive supply unit  4000 . In order to attach the insert  100  to the structure  2000 , the second tube  330  may be initially clamped or shut off (for example, by closing valve  4100 ) so that adhesive may not flow through the second tube  330 . At this point, a vacuum may be applied to the first tube  320  by activating the vacuum system  3000 . This vacuum may draw air out of the cavity  2100  thereby creating a vacuum in the cavity  2100 . Due to the presence of the sealing member  200 , the cavity  2100  may maintain a vacuum state as shown in  FIG. 8C  even when the vacuum system  3000  is shut off. After the air from the cavity  2100  is drawn out, a valve  3100  associated with the vacuum system  3000  may be closed and an adhesive from the adhesive supply unit  4000  may be provided to the cavity  2100  through the second tube  330  which may fill the cavity  2100 .  FIGS. 8E-8I  illustrate an adhesive  4300  flowing through the assembly  1000  and into and throughout the cavity  2100  so that the adhesive  4300  may bond the insert  100  to the structure  2000 . Because the adhesive  4300  is provided in a vacuum, macroscopic voids in the adhesive  4300  are eliminated, thus producing a bond having superior strength characteristics when compared to the conventional art. After the adhesive  4300  has cured, the first and second tubes  320  and  330  may be cut as shown in  FIG. 8J . Although  FIGS. 8A-8J  illustrate the assembly  1000  being inserted into the cavity  2100 , it is understood the assembly  1000 M may be used in lieu of the assembly  1000  without departing from the teachings of  FIGS. 8A-8J  and the above discussion. 
       FIGS. 9A and 9B  illustrate a stud  400  being arranged near an insert  100  which is bonded to the structure  2000 . In example embodiments, the stud  400  may have a first end with first threads  410  and a second end with second threads  420 . In example embodiments, the stud  400  may be arranged near the insert  100  as shown in  FIG. 9A  so that the first threads  410  bear against the threads  122  of the insert  100 . Once in contact, the stud  400  may be rotated so that the stud  400  advances along the cylindrical body  120  of the insert  100  due to the threads  410  of the stud  400  being engaged with the threads  122  of the cylindrical body  122 . In example embodiments, the stud  400  may be advanced along the insert  100  until the stud  400  is at a desired location, for example, as shown in  FIG. 9B . 
       FIG. 10A  illustrates the insert  100  embedded in a structure  2000  as described above.  FIG. 10A  also shows a stud  400  attached to the insert  100  as provided above. In example embodiments, the structure  2000  with the insert  100  embedded therein and the stud  400  may be moved to a second structure  2500  that has a hole  2550  large enough for the stud  400  to pass through. In example embodiments, the structure  2000  with the insert embedded therein and the stud  400  attached thereto may be moved so that the stud  400  passes through the hole  2550  of the second structure  2500  as shown in  FIG. 10B . Once in position, a nut  470  may be attached to the stud  400  to secure the second structure  2500  to the first structure  2000  as shown in  FIGS. 10C and 10D . 
       FIG. 11  illustrates a root of a wind turbine blade attached at the root end to a hub through the use of a series of studs  400  and nuts  450  arranged in a circle. The studs  400  extend from the root of the blade in a manner consistent with that described above and are secured with a nut to a bearing on the hub. This particular nonlimiting example illustrates at least one practical application of example embodiments. 
       FIG. 12A  illustrates another example of an assembly  1000 ′ in accordance with example embodiments and  FIG. 12B  is a cross-section of the assembly  1000 ′ in accordance with example embodiments. As shown in  FIGS. 12A and 12B , the assembly  1000 ′ is substantially similar to the assembly  1000  in that it includes a sealing member  200 , and an applicator unit  300  which may be substantially similar to the sealing member  200  and the applicator unit  300  of the assembly  1000 . However, in example embodiments, the assembly  1000 ′ includes an insert  100 ′ that does not include a flange. Rather, the insert  100 ′ includes only a cylindrical body  120 ′ similar to the previously described cylindrical body  120 . Also, rather than having a flange, the insert  100 ′ includes a washer  110 ′ and a snap ring  115 ′ at one end of a cylindrical body  120 ′. In example embodiments, the snap ring  115 ′ may reside in a groove which may extend around a circumference of the insert  100 ′. In example embodiments, the assembly  1000 ′ may be placed in a cavity  2100  of a structure  2000  as shown in  FIG. 12C . In this case, the sealing member  200  is sandwiched between the washer  110 ′ and the structure  2000  rather than between a flange and the structure  2000 . In example embodiments, an adhesive may be provided under vacuum to secure the insert  100 ′ to the structure  2000  in a manner similar to that provided above. Thus, a detailed description thereof is omitted for the sake of brevity. Also, in example embodiments, the cylindrical body  120 ′ of the insert  100 ′ may include threads  122 ′ as shown in  FIG. 12B  so that a stud may be attached thereto. In example embodiments, the threads  122 ′ may run along an entire length of the cylindrical body  120 ′ or portion of the cylindrical body  120 ′ as shown in  FIG. 12C . On the other hand, the threads may not extend to an end of the cylindrical body  120 ′ and may, instead, resemble the arrangement illustrated in  FIGS. 2D and 3D . 
       FIG. 13A  illustrates another example of an assembly  1000 ″ in accordance with example embodiments and  FIG. 13B  is a cross-section of the assembly  1000 ″ in accordance with example embodiments. As shown in  FIGS. 13A and 13B , the assembly  1000 ″ is substantially similar to the assembly  1000  in that it includes a sealing member  200 , and an applicator unit  300  which may be substantially similar to the sealing member  200  and the applicator unit  300  of the assembly  1000 . However, in example embodiments, the assembly  1000 ″ includes an insert  100 ″ having a cylindrical body  120 ″ and no flange. Rather than having a flange, the insert  100 ″ includes a washer  110 ″ and a nut  115 ″ which interfaces with a threaded end of the insert  100 ″. In example embodiments, the assembly  100 ″ may be placed in a cavity  2100  of a structure  2000  as shown in  FIG. 13C . In this case, the sealing member  200  is sandwiched between the washer  110 ″ and the structure  2000  rather than between a flange and the structure  2000 . In example embodiments, an adhesive may be provided under a vacuum to secure the insert  100 ″ to the structure  2000  in a manner similar to that provided above. Thus, a detailed description thereof is omitted for the sake of brevity. Also, in example embodiments, the cylindrical body  120 ″ of the insert  100 ″ may include threads  122 ″ as shown in  FIG. 13B  so that a stud may be attached thereto. In example embodiments, the threads  122 ″ may run along an entire length of the cylindrical body  120 ″ or portion of the cylindrical body  120 ″ as shown in  FIG. 13B . On the other hand, the threads  122 ″ may not extend to an end of the cylindrical body and may, instead, resemble the arrangement illustrated in  FIGS. 2D and 3D . 
       FIGS. 14A-14C  illustrate the assemblies  1000 ,  1000 ′, and  1000 ″ with a slight modification thereto. In  FIGS. 14A-14C  the assemblies  1000 ,  1000 ′, and  1000 ″ are fitted with spacers  180 ,  180 ′, and  180 ″ to maintain separation between walls of the structure  2000  forming the cavity  2100  and the bodies  120 ,  120 ′, and  120 ″ of the inserts  100 ,  100 ′, and  100 ″. In example embodiments, the spacers  180 ,  180 ′, and  180 ″ may be, but are not limited to, ring type structures or protrusions that may protrude from the outside surfaces of the bodies  120 ,  120 ′, and  120 ″. The spacers  180 ,  180 ′, and  180 ″ may be attached to or directly attached to the bodies  120 ,  120 ′, and  120 .″ 
     Thus far, example embodiments disclose various assemblies  1000 ,  1000 ′, and  1000 ″ with inserts  100 ,  100 ′, and  100 ″ having insert bodies  120 ,  120 ′, and  120 ″ and bearing structures  110 ,  110 ′, and  110 ″ near an end of the insert bodies  120 ,  120 ′, and  120 ″. Each of the assemblies  1000 ,  1000 ′, and  1000 ″ may include an applicator unit  300  in the insert bodies  120 ,  120 ′, and  120 ″, wherein the applicator unit  300  includes a first tube  320 , a second tube  330 , and a sealing body  310  configured to seal the insert bodies  120 ,  120 ′, and  120 ″. Although example embodiments illustrate the insert bodies  120 ,  120 ′, and  120 ″ as being cylindrical structures, example embodiments are not limited thereto. For example, the insert bodies  120 ,  120 ′, and  120 ″ may resemble any tube shaped structure (for example, square tube or rectangular tube or a tube having a hexagonal or octagonal cross section) and the sealing body  310  may be configured to seal an end of the insert consistent with the above description. In each of the assemblies  1000 ,  1000 ′, and  1000 ″ the first tube  320  and the second tube  330  may be arranged in the insert bodies  120 ,  120 ′, and  120 ″. In example embodiments, the sealing members  200  may surround the insert bodies  120 ,  120 ′, and  120 ″ as shown in the figures. In example embodiments, the sealing members  200  may be o-rings. 
       FIGS. 15A and 15B  illustrate a modification of the assembly  1000 . In  FIGS. 15A and 15B , the assembly  1000 M 1  is substantially identical to the assembly  1000  except that the assembly  1000 M 1  does not have a sealing member  200  around the cylindrical body  120 . Rather, in  FIGS. 15A and 15B , a sealing member  200 M 1  (for example, an O-ring) is attached to the structure  2000 . In this latter embodiment, an air tight seal is made when the flange of the assembly  1000 M 1  presses against the sealing member  200 M 1  as shown in  FIG. 15B . In either case, however, the sealing member  200  and the sealing member  200 M 1  are sandwiched between the flanges of the assemblies  1000  and  1000 M 1  and the structure  2000  when the assemblies  1000  and  1000 M 1  are inserted into the cavities  2100 . 
     Other modifications also fall within the inventive concepts of this application. For example, in the assemblies  1000 ′ and  1000 ″ the washers  110 ′ and  110 ″ may be omitted and the snap ring  115 ′ and the nut  115 ″ may serve as bearing structures upon which the sealing member  200  may bear against. In addition, although example embodiments illustrate the applicator unit  300  as being comprised of a sealing body  310  that may be made of an elastic material such as, but not limited to, rubber or a cork type material, example embodiments are not limited thereto. For example, in example embodiments the sealing body  310  may actually be formed by dipping an end of the cylindrical body  120  in rubber to create, at the second end, the sealing body  310 . In the alternative, the sealing body  310  may be expandable foam which is injected into the end of the cylindrical body  120 . As yet another example, the sealing body  310  may be a plate welded to an end of the cylindrical body  120  with two holes through which the tubes  320  and  330  may pass. As yet another example, the insert  100  may be formed through a casting process wherein an end of the insert  100  is closed with at least one hole, for example, two holes, through which the tubes  320  and  330  may pass. In this latter embodiment, it is understood that the portion of the insert closing the end may be considered a sealing body  310 . 
       FIG. 6D  illustrates a cross section of an alternative assembly  1000 * which includes some of the aforementioned alternative features. For example,  FIG. 6D  illustrates the assembly  1000 * as being comprised of a flange  110 *, sealing member  200 *, first tube  320 * and second tube  330 * which may be substantially identical to the previously described flange  110 , sealing member  200 , and first and second tubes  320  and  330 . However, unlike the previously described embodiment, the assembly  1000 * of example embodiments includes a cylindrical body  120 A* having a closed end  120 B*. In this latter example, the cylindrical body  120 A* and closed end  120 B* may be integrally formed as through a casting process. In this nonlimiting example of an assembly  1000 *, the closed end  120 B* may be provided with at least one aperture, for example, a first and second aperture, through which the first and second tubes  320 * and  330 * may pass. 
       FIG. 6E  illustrates a cross section of an alternative assembly  1000 ** which includes some of the aforementioned alternative features. For example,  FIG. 6E  illustrates the assembly  1000 ** as being comprised of a flange  110 ″, sealing member  200 **, a first tube  320 ** and second tube  330 ** which may be substantially identical to the previously described flange  110 , sealing member  200 , and first and second tubes  320  and  330 . However, unlike the previously described embodiment, the assembly  1000 ** of example embodiments includes a cylindrical body  120 A** having an end closed by a plate  120 B** which may be attached to the cylindrical body  120 A** by a conventional method such as, but not limited to, gluing or welding. In this latter example, the cylindrical body  120 A** and the plate  120 B* may be separately formed and then joined together. In this nonlimiting example of an assembly  1000 ″, the plate  120 B* may be provided with at least one aperture, for example, a first and a second aperture, through which the first and second tubes  320 ** and  330 ** may pass. 
       FIGS. 16A-16D  illustrate another nonlimiting example of an assembly  5000 . In particular,  FIG. 16A  represents a first perspective view of the assembly  5000 ,  FIG. 16B  illustrates a second perspective view of the assembly  5000 ,  FIG. 16C  illustrates an exploded view of the example assembly  5000 , and  FIG. 16D  illustrates a cross section view of the assembly  5000 . 
     Referring to  FIGS. 16A-16D , the assembly  5000  may include a sealing member  5100 , an insert  5200 , and an applicator unit  5300 . In example embodiments, the applicator unit  5300  may be substantially identical to the earlier described applicator unit  300 . For example, the applicator unit  5300  may include a body  5310 , a first tube  5320 , and a second tube  5330  which may be substantially identical to the body  310 , the first tube  320 , and the second tube  330  of the applicator unit  300 . Because the applicator unit  5300  may be substantially identical to the applicator unit  300 , a detailed description thereof is omitted for the sake of brevity. 
     In example embodiments, the insert  5200  may resemble a hollow tube, for example, a hollow cylindrical tube and may resemble an insert body. For example, the insert  5200  may resemble a hollow cylinder having an annular cross section. The annular cross section may have an inner diameter D12 and an outer diameter D13. In example embodiments, the inner diameter D12 of the insert  5100  may be large enough to allow a portion of the body  5310  of the applicator unit  5300  to fit therein so that a body  5310  may have a snug fit within the insert  5200  as is consistent with the earlier described example embodiments. The body  5310 , for example, may create an air tight seal at an end of the insert  5200 . 
     Though not shown in the figures, an inner surface  5210  of the insert  5200  may be fully threaded or partially threaded. For example, the inner surface  5210  may include threads similar to the threads  122  of the insert  100  or threads  122 M of the insert  100 M. In example embodiments, the inner surface  5210  may be partially threaded or fully threaded depending on how the insert  5200  is intended to be used. 
     In example embodiments, the sealing member  5100  may include a flange  5120  and a foot  5150 . In example embodiments, the flange  5120  and the foot  5150  may be made of a relatively flexible material, for example, rubber. In example embodiments the foot  5150  may resemble a cylinder having an inner diameter D9 and an outer diameter D10. In example embodiments, the inner diameter D9 may be about the same size as the outer diameter D13 of the insert  5200 . In example embodiments, the inner diameter of the foot  5150 , however, may, in an unattached state, be smaller than the outer diameter D13 of the insert  5200 . However, because the foot  5150  may be made of a resilient material, for example, rubber, the foot  5150  may be deformed to accommodate the insert  5200  therein as is shown in the figures. This may cause a snug tight fit between the foot  5150  and the insert  5200 . 
     In example embodiments, the flange  5120  may extend from the foot  5150 . The flange  5120  may resemble a tapered disk having an outer diameter of D11. As will be explained shortly, ends of the flange  5120  may contact a structure to position the insert  5200  within a cavity of the structure. 
     In example embodiments, the sealing member  5100  may be formed as one integral structure, for example, through a casting or machining process. On the other hand, the foot  5150  and the flange  5120  may be formed separately and then joined together through a joining process, for example, using an adhesive or welding, or another means such as pinning or bolting. 
       FIGS. 17A-17D  illustrate various operations for inserting the assembly  5000  into a cavity  2100  formed in a structure  2000 . In example embodiments, the structure  2000  may be, but is not limited to, a wind turbine blade or any other structure having a cavity  2100  therein. Consistent with the earlier examples, the cavity  2100  may be formed in the structure  2000  via a conventional means, for example, boring or drilling, however the invention is not limited thereto. For example, the structure  2000  may be produced via a casting process and the cavity  2100  may be formed during the casting process. In the alternative, the cavity  2100  may be formed using a punching process. 
     Referring to  FIG. 17A , the cavity  2100  may be formed as a cylindrical cavity having a diameter D8. In order to fit within the cavity  2100 , the outer diameter D13 of insert  5200  may be smaller than the diameter D8 of the cavity. Also, in example embodiments, the outer diameter D10 of the foot  5150  may be about the same size as the diameter D8 of the cavity  2100 . Thus, the foot  5150  may not only position the insert  5200  within the cavity  2100 , but may also act as a seal. In example embodiments, the outer diameter D10 of the foot  5150  may be slightly larger than the diameter of the cavity D8. However, since the foot  5150  may be made of a resilient material, the foot  5150  may be deformed to reduce its outer diameter to ensure a snug fit between the structure  2000  and the foot  5150 . 
     Referring to  FIG. 17B , the insert  5200  of the assembly  5000  may be inserted into the cavity  2100  until ends of the flange  5120  contact the structure  2000 . In this configuration (and consistent with earlier described examples), the space between the insert  5200  and the structure  2000  may be subject to a vacuum through one of the first tube  5320  and second tube  5330 . Under the vacuumed state, an adhesive  5300  may fill spaces between the insert  5200  and the structure  2000  by providing the adhesive through the other of the first tube  5320  and the second tube  5330 . Because the adhesive is provided under a vacuum, macroscopic voids in the adhesive may be eliminated. After the adhesive is cured, the sealing member  5100  may be removed producing the structure illustrated in  FIG. 17D . 
     Certain features of example embodiments are not intended to limit the invention. For example, while the bodies  120 ,  120 M,  120 ′,  120 ″, and  5200  are described and illustrated as cylinders, the bodies  120 ,  120 M,  120 ′,  120 ″, and  5200  may have another shape such as, but not limited to, square or rectangular tubes or tubes having an elliptical cross-section, a hexagonal cross section, or an octagonal cross-section. Similarly, the cavity  2100  in the structure  2000  described above are not required to be cylindrical holes formed in a structure. For example, the cavity  2100  may have a square, rectangular, elliptical, hexagonal, or octagonal profile. In addition, the inserts need not be hollow. For example, the inserts may be substantially solid members with channels running therethrough to provide vacuum and adhesive as described above. 
     Example embodiments of the invention have been described in an illustrative manner. It is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of example embodiments are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.