Woven metallic reinforcement and method of fabricating same

Abstract
A triaxial woven structure is provided including a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs. A second rigid member has a serpentine shape comprising a second plurality of peaks and a second plurality of troughs. A peak of the first rigid member is disposed within a trough of the second rigid member. A third rigid member has a substantially linear shape and is disposed within a trough of the first rigid member and a peak of the second rigid member.
Description
FIELD OF THE INVENTION

The present invention relates to triaxial structures. More specifically, the present invention relates to triaxial structures that provide reinforcement support.


BACKGROUND OF THE INVENTION

The use of reinforcing members in the construction industry is well known. Such reinforcing members include what is commonly known as “rebar” or reinforcing bar made from a heavy gauge wire. In construction, such rebar members are laid out in a pattern with one set of members overlying an orthogonal set of members in a biaxial configuration. These members are then tied together to prevent movement of the members using tie wires.


This approach has drawbacks, however, because of the time necessary to tie together the reinforcing members at each cross point. This structure also has a tendency to shift during assembly or thereafter because the members are not locked together. Furthermore, although these reinforcing members are useful in structures in which the reinforcing members are encased, such as in a concrete support, stand-alone reinforcing members are not adequate to provide support.


There is a need for a structural assembly that is capable of withstanding transverse and lateral loads without shifting, and capable of ease of assembly.


SUMMARY OF THE INVENTION

According to one aspect of this invention, a triaxial woven structure includes a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs. A second rigid member has a serpentine shape comprising a second plurality of peaks and a second plurality of troughs. A peak of the first rigid member is disposed within a trough of the second rigid member. A third rigid member has a substantially linear shape and is disposed within a trough of the first rigid member and a peak of the second rigid member.


According to another aspect of this invention, a triaxial woven structure includes a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs. A second rigid member has a serpentine shape comprising a second plurality of peaks and a second plurality of troughs. The second rigid member is a mirror-image of the first rigid member. A third rigid member has a serpentine shape comprising a third plurality of peaks and a third plurality of troughs. A peak of the first rigid member is disposed within a trough of the third rigid member. A fourth rigid member has a serpentine shape comprising a fourth plurality of peaks and a fourth plurality of troughs. The fourth rigid member is a mirror-image of the third rigid member. A peak of the fourth rigid member is disposed within a trough of the second rigid member. Another peak of the fourth rigid member is disposed within a trough of the third rigid member. A fifth rigid member has a substantially linear shape and is disposed within the troughs of the first rigid member and the third rigid member and the peaks of the second rigid member and the fourth rigid member.


According to yet another aspect of this invention, a composite structure includes a substrate comprising a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs. A second rigid member has a serpentine shape comprising a second plurality of peaks and a second plurality of troughs. A peak of the first rigid member is disposed within a trough of the second rigid member. A third rigid member is disposed within a trough of the first rigid member and a peak of the second rigid member. A first layer of material is coupled to a first surface of the substrate.


According to another aspect of this invention, a triaxial woven structure includes a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs. A second rigid member has a serpentine shape comprising a second plurality of peaks and a second plurality of troughs. A peak of the first rigid member is disposed within a trough of the second rigid member. A third rigid member has a substantially spiral shape and is disposed within a trough of the first rigid member and a peak of the second rigid member.


According to yet another aspect of this invention, a triaxial woven structure includes a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs. A second rigid member has a serpentine shape comprising a second plurality of peaks and a second plurality of troughs. A peak of the first rigid member is disposed within a trough of the second rigid member. A third rigid member has a substantially linear shape and is disposed within a trough of the first rigid member and a peak of the first rigid member, and a trough of the second rigid member and a peak of the second rigid member.


According to another aspect of this invention, a method of forming a triaxial woven structure includes providing a first rigid member and a second rigid member. Each of the first rigid member and the second rigid member is shaped into a serpentine by forming a respective plurality of peaks and a respective plurality of troughs therein. A peak of the first rigid member is placed within a trough of the second rigid member. A third rigid member having a substantially linear shape is inserted within a trough of the first rigid member and a peak of the second rigid member.


According to yet another aspect of this invention, a method of forming a triaxial woven structure includes providing a first rigid member and a second rigid member. Each of the first rigid member and the second rigid member is shaped into a serpentine by forming a respective plurality of peaks and a respective plurality of troughs therein. A peak of the first rigid member is placed within a trough of the second rigid member. A third rigid member having a substantially spiral shape is rotated within a trough of the first rigid member and a peak of the second rigid member.




BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 is a perspective view of an exemplary embodiment of a triaxial woven structure having a substantially planar form according to aspects of this invention;



FIG. 2 is a perspective view of the triaxial woven structure illustrated in FIG. 1 showing the assembly configuration of a first rigid member;



FIG. 3 is a perspective view of the triaxial woven structure illustrated in FIG. 1 showing the assembly configuration of a second rigid member;



FIG. 4 is a perspective view of another exemplary embodiment of a triaxial woven structure having a substantially circular cross-section according to aspects of this invention;



FIG. 5 is an end view of the triaxial woven structure illustrated in FIG. 4;



FIG. 6 is a side view of the triaxial woven structure illustrated in FIG. 4;



FIG. 7 is a perspective view of yet another exemplary embodiment of a triaxial woven structure having a substantially I-shaped cross-section according to aspects of this invention;



FIG. 8 is an exploded end view of the triaxial woven structure illustrated in FIG. 7;



FIG. 9 is an exploded top view of the triaxial woven structure illustrated in FIG. 8;



FIG. 10 is a perspective view of another exemplary embodiment of a triaxial woven structure having a first and second layer of material according to aspects of this invention;



FIG. 11 is a front view of the triaxial woven structure having a first and second layer of material illustrated in FIG. 10;



FIG. 12 is a perspective view of yet another exemplary embodiment of a triaxial woven structure having a substantially planar form according to aspects of this invention;



FIG. 13 is a perspective view of another exemplary embodiment of a triaxial woven structure having a substantially planar form according to aspects of this invention; and



FIG. 14 is a top view of the triaxial woven structure illustrated in FIG. 13.




DETAILED DESCRIPTION OF THE INVENTION

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.


Referring to FIG. 1, there is shown a triaxial woven structure 10 having a substantially planar form. Triaxial woven structure 10 includes first rigid members 12, each having a serpentine shape comprising a first plurality of peaks 14 and a first plurality of troughs 16. Each second rigid member 18 has a serpentine shape comprising a second plurality of peaks 20 and a second plurality of troughs 22. Peaks 14 of first rigid members 12 are disposed within troughs 22 of second rigid members 18. Each third rigid member 24 has a substantially linear shape and is disposed within troughs 16 of first rigid member 12 and peaks 20 of second rigid member 18. Third rigid members 24 lock the first 12, second 18, and third 24 rigid members together.



FIGS. 2 and 3 illustrate the assembly configuration of the rigid members with respect to one another. More specifically, FIG. 2 illustrates that first rigid member 12 is inserted in a downward direction “D,” while FIG. 3 illustrates that the second rigid member 18 is inserted in an upward direction “U.” Peaks 14 of first rigid members 12 are disposed within troughs 22 of second rigid members 18. In other words, first 12 and second 18 rigid members are not interlaced, and first rigid members 12 remain configured on top of second rigid members 18. Such an arrangement creates open spaces between peaks 20 of second rigid members 18 and troughs 16 of first rigid members 12 through which linear-shaped third rigid members 24 may be inserted. The insertion of third rigid members 24 locks the first 12, second 18, and third 24 rigid members together. This locking feature is a key characteristic of the triaxial woven structure 10, providing ease of assembly and structural integrity as will described subsequently.


The configuration of the triaxial woven structure 10 is such that the first 12, second 18, and third 24 rigid members form triangles. The angle between first rigid member 12 and second rigid member 18 is between about 19 degrees and 71 degrees. The angle between first rigid member 12 and third rigid member 24 is between about 19 degrees and 71 degrees. In one exemplary embodiment, the angle between first rigid member 12 and second rigid member 18 is about 60 degrees, and the angle between first rigid member 12 and third rigid member 24 is about 60 degrees.


In one exemplary embodiment, each of the first 12, second 18, and third 24 rigid members has a substantially circular cross-section, The cross-sectional shape of the first 12, second 18, and third 24 rigid members is not limited to circular, as each of first 12, second 18, and third 24 rigid members may have a substantially rectangular cross-section, or any other suitable shape capable of maintaining the structural integrity of the triaxial woven structure 10.


The first 12, second 18, and third 24 rigid members are formed from a solid material. Such material may be steel, aluminum, copper, a polymer, or any other suitable material strong enough to maintain its shape and rigid enough to maintain the structural integrity of the triaxial woven structure 10. The formation of the first 12, second 18, and third 24 rigid members is not limited to solid material, as each of the first 12, second 18, and third 24 rigid members may be formed from a hollow material.


The configuration of the rigid members with respect to one another allows for easy assembly of triaxial woven structure 10. More specifically, the locking feature achieved by the insertion of third rigid members 24 eliminates the necessary step of tying together reinforcing members at each cross point for conventional rebar. Such ease of assembly saves valuable production time. Furthermore, the rigidity of triaxial woven structure 10 due to the material selection combined with the locking feature helps to ensure the structure is capable of withstanding transverse and lateral loads without shifting during assembly or thereafter. The rigid members may be assembled off-site to form triaxial woven structure 10. Alternatively, the rigid members may be assembled at the application site to form triaxial woven structure 10.



FIGS. 4-6 illustrate a triaxial woven structure 40 having a substantially circular cross-section. Similar to the triaxial woven structure 10 described previously with reference to FIGS. 1-3, triaxial woven structure 40 includes first rigid members 42, each having a serpentine shape comprising a first plurality of peaks 44 and a first plurality of troughs 46. Each second rigid member 48 has a serpentine shape comprising a second plurality of peaks 50 and a second plurality of troughs 52. Peaks 44 of first rigid members 42 are disposed within troughs 52 of second rigid members 48. Each third rigid member 54 has a substantially linear shape and is disposed within troughs 46 of first rigid member 42 and peaks 50 of second rigid member 48. Third rigid members 54 lock the first 42, second 48, and third 54 rigid members together.


The assembly and configuration of the rigid members of this embodiment with respect to one another are essentially the same as those of the substantially planar triaxial woven structure 10 described previously with reference to FIGS. 1-3. In other words, triaxial woven structure 40 having a substantially circular cross-section is essentially substantially planar triaxial woven structure 10 rolled into a substantially cylindrical shape.



FIGS. 7-9 illustrate a triaxial woven structure 70 having a substantially I-shaped cross-section. Triaxial woven structure 70 includes first rigid members 72, each having a serpentine shape comprising a first plurality of peaks 74 and a first plurality of troughs 76. Each second rigid member 78 has a serpentine shape comprising a second plurality of peaks 80 and a second plurality of troughs 82. Second rigid members 78 are mirror-images of first rigid member 72. Each third rigid member 84 has a serpentine shape comprising a third plurality of horizontal peaks 86H and vertical peaks 86V and a third plurality of horizontal troughs 88H, 88H′ and vertical troughs 88V. Peaks 74 of first rigid members 72 are disposed within horizontal troughs 88H of third rigid members 84. Each fourth rigid member 90 has a serpentine shape comprising a fourth plurality of horizontal peaks 92H and vertical peaks 92V and a fourth plurality of horizontal troughs 94H, 94H′ and vertical troughs 94V. Fourth rigid members 90 are a mirror-images of third rigid members 84. Horizontal peaks 92H of fourth rigid members 90 are disposed within troughs 82 of second rigid members 78. Vertical peaks 92V of fourth rigid members 90 are disposed within vertical troughs 88V of third rigid members 84. Each fifth rigid member 96 has a substantially linear shape and is disposed within troughs 76, 88H′, 94V/94H′ of first rigid members 72, third rigid members 84, and fourth rigid members 90 respectively, and peaks 80, 86H/V, 92H of second rigid members 78, third rigid members 84, and fourth rigid members 90 respectively.


The assembly and configuration of the rigid members of this embodiment with respect to one another are essentially the same as those of the substantially planar triaxial woven structure 10 described previously with reference to FIGS. 1-3. In other words, triaxial woven structure 70 having a substantially I-shaped cross-section is essentially substantially planar triaxial woven structure 10 configured in substantially perpendicular planes.


Referring to FIGS. 10 and 11, there is shown an exemplary composite structure 98 that includes a substrate 100 comprising first rigid members 112, each having a serpentine shape comprising a first plurality of peaks 114 and a first plurality of troughs 116. Each second rigid member 118 has a serpentine shape comprising a second plurality of peaks 120 and a second plurality of troughs 122. A peak 114 of the first rigid member 112 is disposed within a trough 122 of the second rigid member 118. Each third rigid member 124 has a substantially linear shape and is disposed within a trough 116 of the first rigid member 112 and a peak 120 of the second rigid member 118. A first layer of material 126 is coupled to a top surface of the substrate 100, while a second layer of material 128 is coupled to a bottom surface of the substrate 100. In one exemplary embodiment, the first 126 and second 128 layers of material are adhered to the substrate 100 by welding, for example. The present invention is not limited to welding, however, as the first 126 and second 128 layers of material may be adhered to the substrate 100 via an adhesive, or any other suitable means of adhering the components. The mating areas of the top and bottom surfaces of the substrate 100 that are coupled to the first 126 and second 128 layers of material respectively may be flattened (not shown) if desired to increase the available surface area.


The assembly and configuration of the rigid members of this embodiment with respect to one another are essentially the same as those of the substantially planar triaxial woven structure 10 described previously with reference to FIGS. 1-3.


Referring to FIG. 12, there is shown a triaxial woven structure 130 having a substantially planar form. Triaxial woven structure 130 includes first rigid members 132 having a serpentine shape comprising a first plurality of peaks 134 and a first plurality of troughs 136. Each second rigid member 138 has a serpentine shape comprising a second plurality of peaks 140 and a second plurality of troughs 142. Peaks 134 of first rigid members 132 are disposed within troughs 142 of second rigid members 138. Each third rigid member 144 has a substantially spiral shape and is disposed within troughs 136 of first rigid members 132 and peaks 140 of second rigid members 138.


The assembly and configuration of the rigid members of this embodiment with respect to one another are essentially the same as those of the substantially planar triaxial woven structure 10 described previously with reference to FIGS. 1-3. Unlike linear-shaped third rigid members 24 of triaxial woven structure 10 that are inserted through open spaces as explained previously, however, spiral-shaped third rigid members 144 of triaxial woven structure 130 are rotated through open spaces created between troughs 136 of first rigid members 132 and peaks 140 of second rigid members 138. The rotation of third rigid members 144 through the open spaces locks the first 132, second 138, and third 144 rigid members together.



FIGS. 13 and 14 illustrate another exemplary embodiment of a triaxial woven structure having a substantially planar form. Similar to the triaxial woven structure 10 described previously with reference to FIGS. 1-3, triaxial woven structure 150 includes first rigid members 152, each having a serpentine shape comprising a first plurality of peaks 154 and a first plurality of troughs 156. Each second rigid member 158 has a serpentine shape comprising a second plurality of peaks 160 and a second plurality of troughs 162. Peaks 160 of second rigid members 158 are elongated, and are disposed within troughs 156 of first rigid members 152, which are also elongated. Each third rigid member 164 has a substantially linear shape and is disposed within peaks 154 and troughs 156 of first rigid members 152, and peaks 160 and troughs 162 of second rigid members 158. Third rigid members 164 lock first 152, second 158, and third 164 rigid members together.


The elongated feature of peaks 160 of second rigid members 158 and troughs 156 of first rigid members 152 provides greater surface area for adherence to first and second layers of material to form a composite structure, similar to exemplary composite structure 98 described previously with reference to FIGS. 10 and 11.


The assembly and configuration of the rigid members of this embodiment with respect to one another are essentially the same as those of the substantially planar triaxial woven structure 10 described previously with reference to FIGS. 1-3, with some notable differences. The first 152, second 158, and third 164 rigid members of triaxial woven structure 150 are configured in parallel pairs. Each first 152 and second 158 rigid member is positioned offset relative to its adjacent member. Furthermore, unlike the arrangement of the first 12 and second 18 rigid members of triaxial woven structure 10, which creates open spaces between peaks 20 of second rigid members 18 and troughs 16 of first rigid members 12 through which linear-shaped third rigid members 24 may be inserted, the arrangement of the first 152 and second 158 rigid members of triaxial woven structure 150 creates open spaces between both peaks 154, 160 and troughs 156, 162 of the first 152 and second 158 rigid members, respectively, through which linear-shaped third rigid members 164 may be inserted.


The exemplary embodiments of triaxial woven structures 10, 40, 70, 98, 100, 130, and 150 described herein are typically utilized as rebar encased within concrete structures. Applications include, but are not limited to, highways, bridges, building foundations and support columns, parking garages, and coastal facilities. However, the present invention is not limited to encased rebar. Due to their structural strength and integrity, triaxial woven structures 10, 40, 70, 98, 100, 130, and 150 may be utilized as stand-alone structures.


While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.

Claims
  • 1. A triaxial woven structure comprising: a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs; a second rigid member having a serpentine shape comprising a second plurality of peaks and a second plurality of troughs, a peak of said first rigid member disposed within a trough of said second rigid member; and a third rigid member having a substantially linear shape and disposed within a trough of said first rigid member and a peak of said second rigid member.
  • 2. The structure according to claim 1, wherein said third rigid member locks said first, second, and third rigid members together.
  • 3. The structure according to claim 1, wherein said first rigid member, said second rigid member, and said third rigid member form a triangle.
  • 4. The structure according to claim 3, wherein an angle between said first rigid member and said second rigid member is between about 19 degrees and 71 degrees.
  • 5. The structure according to claim 3, wherein an angle between said first rigid member and said third rigid member is between about 19 degrees and 71 degrees.
  • 6. The structure according to claim 1, wherein each of said first, second, and third rigid members has a substantially circular cross-section.
  • 7. The structure according to claim 1, wherein at least one of said first, second, and third rigid members has a substantially rectangular cross-section.
  • 8. The structure according to claim 1, wherein said first, second, and third rigid members are a reinforcing bar material.
  • 9. The structure according to claim 1, wherein said first, second, and third rigid members are formed from a solid material.
  • 10. The structure according to claim 9, wherein said first, second, and third rigid members are formed from at least one of i) steel, ii) aluminum, iii) copper, and iv) a polymer.
  • 11. The structure according to claim 1, wherein at least one of said first, second, and third rigid members is formed from a hollow material.
  • 12. The structure according to claim 1, wherein said structure has a substantially planar form.
  • 13. The structure according to claim 1, wherein said structure has a substantially circular cross-section.
  • 14. A triaxial woven structure comprising: a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs; a second rigid member having a serpentine shape comprising a second plurality of peaks and a second plurality of troughs, wherein said second rigid member is a mirror-image of said first rigid member; a third rigid member having a serpentine shape comprising a third plurality of peaks and a third plurality of troughs, a peak of said first rigid member disposed within a trough of said third rigid member; a fourth rigid member having a serpentine shape comprising a fourth plurality of peaks and a fourth plurality of troughs, wherein said fourth rigid member is a mirror-image of said third rigid member, a peak of said fourth rigid member is disposed within a trough of said second rigid member, and another peak of said fourth rigid member is disposed within a trough of said third rigid member; and a fifth rigid member disposed within said troughs of said first, third, and fourth rigid member and said peaks of said second, third, and fourth rigid member.
  • 15. The structure according to claim 14, wherein i) a first portion of said plurality of peaks and said plurality of troughs of said third rigid member are substantially orthogonal to a remaining portion of said plurality of peaks and said plurality of troughs of said third rigid member, and ii) a first portion of said plurality of peaks and said plurality of troughs of said fourth rigid member are substantially orthogonal to a remaining portion of said plurality of peaks and said plurality of troughs of said fourth rigid member.
  • 16. The structure according to claim 14, wherein said structure has a substantially I-shaped cross-section.
  • 17. A composite structure comprising: a substrate comprising: i) a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs, ii) a second rigid member having a serpentine shape comprising a second plurality of peaks and a second plurality of troughs, a peak of said first rigid member disposed within a trough of said second rigid member, and iii) a third rigid member having a substantially linear shape disposed within a trough of said first rigid member and a peak of said second rigid member; and a first layer of material coupled to a first surface of said substrate.
  • 18. The structure according to claim 17, wherein said third rigid member has a substantially linear shape.
  • 19. The structure according to claim 17, wherein said third rigid member has a substantially spiral shape.
  • 20. The structure according to claim 17, further comprising a second layer of the material coupled to a further surface of said substrate, wherein said first layer of material is adhered to said substrate by one of welding and an adhesive.
  • 21. A triaxial woven structure comprising: a first rigid member having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs; a second rigid member having a serpentine shape comprising a second plurality of peaks and a second plurality of troughs, a peak of said first rigid member disposed within a trough of said second rigid member; and a third rigid member having a substantially spiral shape and disposed within a trough of said first rigid member and a peak of said second rigid member.
  • 22. The structure according to claim 21, wherein said structure has a substantially planar form.
  • 23. A triaxial woven structure comprising: a pair of first rigid members adjacent one another, each having a serpentine shape comprising a first plurality of peaks and a first plurality of troughs; a pair of second rigid members adjacent one another, each having a serpentine shape comprising a second plurality of peaks and a second plurality of troughs, a peak of said first rigid members disposed within a trough of said second rigid members; and a third rigid member having a substantially linear shape and disposed within a trough of a first one of said pair of first rigid members and a peak of a second one of said first rigid members, and a trough of a first one of said pair of second rigid members and a peak of a second one of said pair of second rigid members.
  • 24. The structure according to claim 23, wherein said third rigid member locks said first, second, and third rigid members together.
  • 25. The structure according to claim 23, wherein said first rigid member, said second rigid member, and said third rigid member form a triangle.
  • 26. The structure according to claim 25, wherein an angle between said first rigid member and said second rigid member is between about 19 degrees and 71 degrees.
  • 27. The structure according to claim 25, wherein an angle between said first rigid member and said third rigid member is between about 19 degrees and 71 degrees.
  • 28. The structure according to claim 23, wherein each of said first, second, and third rigid members has a substantially circular cross-section.
  • 29. The structure according to claim 23, wherein at least one of said first, second, and third rigid members has a substantially rectangular cross-section.
  • 30. The structure according to claim 23, wherein said first, second, and third rigid members are a reinforcing bar material.
  • 31. The structure according to claim 23, wherein said first, second, and third rigid members are formed from a solid material.
  • 32. The structure according to claim 31, wherein said first, second, and third rigid members are formed from at least one of i) steel, ii) aluminum, iii) copper, and iv) a polymer.
  • 33. The structure according to claim 23, wherein at least one of said first, second, and third rigid members is formed from a hollow material.
  • 34. The structure according to claim 23, wherein said structure has a substantially planar form.
  • 35. A method of forming a triaxial woven structure comprising the steps of: a) providing a first rigid member and a second rigid member; b) shaping each of said first rigid member and said second rigid member into a serpentine by forming a respective plurality of peaks and a respective plurality of troughs therein; c) placing a peak of said first rigid member within a trough of said second rigid member; and d) inserting a third rigid member having a substantially linear shape within a trough of said first rigid member and a peak of said second rigid member.
  • 36. The method according to claim 35, further comprising the steps of repeating steps c) and d).
  • 37. A method of forming a triaxial woven structure comprising the steps of: a) providing a first rigid member and a second rigid member; b) shaping each of said first rigid member and said second rigid member into a serpentine by forming a respective plurality of peaks and a respective plurality of troughs therein; c) placing a peak of said first rigid member within a trough of said second rigid member; and d) rotating a third rigid member having a substantially spiral shape within a trough of said first rigid member and a peak of said second rigid member.
  • 38. The method according to claim 37, further comprising the steps of repeating steps c) and d).