Abstract:
The present invention is a general structural member assembly. A basic structural unit of the present invention has two adjacent shafts, both further having a cross sectionally triangular shape with a longitudinal side completely or substantially mostly removed to form legs. The leg ends are formed or machined such that they present two outward surfaces generally parallel to the the open face of a first adjacent shaft. The outward surfaces of the leg ends are then positionally fixed, albeit with some flexible movement in some embodiments, to generally have a parallel and longitudinal interface with the longitudinal outside edges of a solid side of a second shaft. Additional shafts may be added in this open side opposed to solid side assembly.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to structural members. 
     In a previously filed application, an invention was disclosed relating to rods and shafts which are suitable for use in the construction of tapered and parallel edged fishing rods, golf shafts, yacht masts, sailboard masts and the like. 
     Fishing rods, golf shafts, yacht masts, sailboard masts, and the like are generally constructed of fibre-resin composites or metal in the form of solid rods or tubes. Hollow composite rods are accepted as being superior in performance to solid composite rods in light weight uses but they are delicate and easily damaged. Solid metal rods and metal tubes are generally inferior in flexural characteristics to the composite rods. It will be apparent to the skilled person that the teaching of rod or shaft construction in the above arts may be effectively applied to other heavier, industrial or civil engineering uses as well. 
     Tapered, tubular composite rods require expensive, accurately ground metal mandrels to produce the taper necessary for the desired performance and there are considerable difficulties in manufacturing with uniform wall thickness. An attempt to overcome to some extent the problems associated with tubular rod manufacture from composite materials is the subject of U.S. Pat. Nos. 4,582,758 and 5,229,187 (referred to herein respectively as Bruce &amp; Walker and McGinn), the enabling teaching of which are incorporated herein. 
     Both patents relate to the provision of rods of polygonal cross-section formed by a plurality of elements of certain geometrical cross-section. Bruce &amp; Walker describes that each of the elements has a base part of a fibre reinforced plastic material and an apex of part of a rigid plastic material foam. 
     McGinn, on the other hand, adopted a method of using T-sections made from fibre reinforced plastic material. The method by which the joints of the top ends of T-sections in McGinn are joined is shown in FIG. 5 of that patent. It is seen that the top ends of the T-sections must be molded or machined to a relatively small tolerance to accommodate matching of the several faces of the T-sections to each other. Both these rods, while they solve wall thickness variation problems and obviate the need for expensive mandrels for forming are difficult to make in the required thickness. 
     Bruce &amp; Walker experience difficulties in the required stiffness for heavy load application such as are encountered in deep sea fishing and similar application without resorting to excessive composite wall thickness. The technology applied by McGinn addresses the stiffness required in heavy load application, but the mere nature of this technology reduces the ability to make the rods flexible for fly rod application in the various line weights required. Neither invention has adequately addressed the problem of torque encountered in small structures such as golf shafts. 
     The problem is severe in the case of Bruce &amp; Walker. The McGinn technology has gone some way to addressing this problem with sufficient torque being removed from fishing rods to make them user acceptable. However, the problem of torque is highlighted when both products are used as golf shafts. Any torque in the shafts alters the angle of the golf club head when it comes in contact with the ball, which is unacceptable to the playing golfing public. 
     It is therefore one object of the present invention to provide a rod, shaft, etc., which obviates or at least minimizes the aforementioned disadvantages of conventional rods and those of Bruce &amp; Walker and McGinn. 
     SUMMARY OF THE INVENTION 
     The present invention is a general structural member assembly. Two embodiments of a a basic structural unit of the present invention have two adjacent shafts, both further having a cross sectionally triangular shape with a longitudinal side completely or substantially mostly removed. The “open” side, i.e., the side completely or substantially mostly removed, in cross section presents two “leg” ends, i.e., the ends distal to the vertex of the longitudinal sides that at structurally intact and maintain the vertex of the two solid sides and such that the legs are approximately equal in length. The leg ends are formed or machined such that they present two outward surfaces generally parallel to the the open face of a first adjacent shaft. The outward surfaces of the leg ends are then positionally fixed, albeit with some flexible movement in some embodiments, to generally have a parallel and longitudinal interface with the longitudinal outside edges of a solid side of a second shaft. Additional shafts may be added in this open side opposed to solid side basic assembly unit to form a single joined polygonal shaft assembly where all of the open sides are enclosed with a solid side, the additions proceeding in a circular fashion to form a polygonal cross section of exceptional strength and torsional resistance. Where a more extensive structure is desired, additional whole or partial sections of these joined polygonal shafts may be joined along one or more of their solid faces longitudinally along the solid faces of a first joined polygonal shaft, or portion thereof, at least preserving one basic structural unit of an open side positionally fixed to a closed side. 
     In the first of the two above embodiments, the open side completely lacks any portion of the longitudinal face of the triangular cross section of the adjacent shafts. The second of the two above embodiments comprises two short opposing extensions from the ends of the solid sides without such in the first embodiment, such that a short portion of the open side is formed along those legs to improve flexing strength. 
     In a third embodiment of a basic structural unit, two adjacent shafts also have open sides, a first adjacent shaft having solid sides and legs similar to those of the first embodiment except that an outside facing solid side has a cross section first length that is longer than that of the joined polygon enclosed solid side by about the thickness of a solid side. A second adjacent shaft also has an outside facing solid side of about the same cross section length and leg surface as that of the first adjacent leg. The joined polygon enclosed solid side of the second adjacent shaft also has the same length as its outside facing solid side, although it is further extended from its leg end in a direction such that the leg surface of the shortened leg of the first adjacent shaft presses in a force transmitting connection on an inside surface of the extension of the second adjacent shaft in an assembled arrangement as a basic structural unit. The assembled and combined cross section length of the shortened joined polygon enclosed solid side of the first adjacent shaft with the thickness of the extension of the joined polygon enclosed solid side of the second adjacent shaft then presents an outside surface of the extension as a leg surface effective with the leg surface of the outside facing solid side of the first adjacent shaft to then fixedly oppose the outside surface of a joined polygon enclosed solid side of another adjacent shaft such as that of the second adjacent shaft. 
     It is a further improvement of the present three basic structural units to provide single layer or laminar binding around the outside facing solid sides of a joined polygonal shaft assembly without any further securement, gluing, welding, bolting, soldering or the like between the adjacent shafts such that the adjacent shafts remain in positions sufficiently fixed to effect the support required of their application. This wrapped, un-secured embodiment is useful when sliding flexure of the adjacent shafts are desired, especially when a type of bending or twisting force is not so great as to break down the surrounding support. 
     It is a further improvement of the present three basic structural units to provide a single bonded axial connection to the central axis of the joined polygonal shafts, whereby the bonding may be accomplished with glues, expoxies, weld connections, solder or other methodologies (such as bolting and piercing/riveting methods) appropriate for securement of the central axis formed by the zone of leg ends of the joined polygon enclosed solid sides. Such joined polyonal shafts may then be bundled and secured together or with other longitudinal supports about their periphery such as described in the previous paragraph. 
     It is a further improvement of the present three basic structural units to provide bonding as described in the previous paragraph is provided only for the interface between the leg surface of the outside facing solid side and the abutting vertex zone of the joined polygon enclosed solid side of the adjacent shaft. A joined polygon shaft of this embodiment thus comprises an outer edge of longitudinally bonded adjacent shafts while leaving free for sliding movement the zone of leg ends of the joined polygon enclosed solid sides during flexing or torsional movement. 
     It is a further improvement of the present invention to combine the wrapping securement, central axis or outside facing seam bonding in combination with each other to obtain specific performance characterisitics of flexing and torsional response. For example, the combination of a wrapping securement and the central axis bonding permits some slidable flexion in the interface between the leg surface of the outside facing solid side and the abutting vertex zone of the joined polygon enclosed solid side of the adjacent shaft while stiffening the overall structure with a non-bonding sleeve under the stiffening wrapping securement. 
     It is yet another embodiment of the present invention to form joined polygonal shafts with at least three or more sides. Any of the basic structural units are easily adapted to form joined polygonal shafts of any number of cross section outside solid sides so long as that number is three or more. 
     Additional inventive supports for the basic structural units comprise inserts into or fills for the void between the outer face of a polygon enclosed solid side of a first adjacent shaft and the inside faces of a the outside facing solid side and a polygon enclosed solid side of a second adjacent shaft, forming a longitudinal void with a roughly triangular shape. Longitudinal support inserts or fills into this void may have a cross section shape of a plane, trangle, circle (or oblate), separate solid rods, solid fill (urethane foam, epoxy, solder or metal), or fusible structurally supportive material. Appropriately smaller adjacent shafts of the present invention are also adaptable to be inserted alone or in a nesting relationship as longitudinal support for insertion into such a longitudinal void. Another class of inventive supports comprise planar inserts longitudinally interposed between and along the outer face of the joined polygon enclosed solid side of a first adjacent shaft and the leg surfaces of a second adjacent shaft. It has been found in prototype models of this planar insert embodiment that very thin, even flexible plastic material may comprise the basic structural unit while providing a planar insert bonded to the outer face of a joined polygon enclosed solid side that creates a joined polygon shaft of superior strength. 
     The basic structural units of the present invention may be used in such a wide number of applications that the types of additional supports described in the preceding paragraph may be applied separately or in combination along the length of any single longitudinal void. For example, in an antenna, ship mast or hull, or building joist where variable strength, flexibility and resistance to torsion may be desirable, a nested set of smaller adjacent shafts in one section of the longitudinal void may be easily reduced to an identical set of such supports less the innermost nested adjacent support shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a somewhat exploded cross-sectional view of the rod of the present invention, wherefore V sections and reinforcing V sections are shown in unsecured relationship. 
     FIG. 2 is a closer view of the V trough point of a V section, wherein the V section is filled with strengthening filler, as described below, and an exterior surface is shown with supporting laminates to be arranged in wrapping support about the assembled V sections. 
     FIG. 3 is the assembled and secured cross-sectional view of the V sections and reinforcing V-sections shown in FIG.  1 . 
     FIG. 4 is a first embodiment of the basic structural unit of the present invention. 
     FIG. 5 is a second embodiment of the basic structural unit of the present invention. 
     FIG. 6 is a third embodiment of the basic structural unit of the present invention. 
     FIG. 7 is a joined polygonal shaft of the first embodiment of the basic structural unit of the present invention with a hexagonal circumferential shape. 
     FIG. 8 is a joined polygonal shaft of the second embodiment of the basic structural unit of the present invention. 
     FIG. 9 is a joined polygonal shaft of the third embodiment of the basic structural unit of the present invention. 
     FIG. 10 is a joined polygonal shaft of the first embodiment of the basic structural unit of the present invention with a triangular circumferential shape. 
     FIG. 11 is a joined polygonal shaft of the first embodiment of the basic structural unit of the present invention with a hexagonal circumferential shape and further showing longitudinal insert supports for the longitudinal void. 
     FIG. 12 is a joined polygonal shaft of the first embodiment of the basic structural unit of the present invention with a hexagonal circumferential shape, whereby an adjacent shaft is withdrawn to illustrate the positioning of planar longitudinal supports that may be effectively applied about the inner and outer faces of an adjacent shaft. 
     FIG. 13 is a set of joined polygonal shafts of the first embodiment of the basic structural unit of the present invention with a hexagonal circumferential shape forming an enlarged structural member. 
     FIG. 14 is an upper front view of a weld mesh formed as the first embodiment of the present invention. 
    
    
     DESCRIPTION OF THE INVENTION 
     According to the present invention, there is provided a rod comprising a plurality of elongated V section elements wherein the open end of the V section element is joined to one leg of the adjacent V section elements. The other leg of the V section element forms the outer surface of the polygonal shape. The extremities of the inner leg of the V section element extend in a direction towards a common axis. 
     Practical consideration in rod construction will generally limit the number of V section elements to 12 and most preferably to 6. Hexagonal structures are the most preferred. 
     The elongate V section elements may have parallel or tapered edges depending on the particular end use to which the rod, shaft etc. is to be put. The V section elements may be fabricated from a wide range of materials, the preferred materials being those which provide maximum longitudinal stiffness and have low weight. Particularly suitable materials are fibre reinforced plastics materials such glass, carbon, polyimide and boron fibre in admixture with polyester, epoxy, phenol and thermoplastic resins. Metals such as aluminum, brass, titanium and fibre reinforced metals, and metal composites such as fibre reinforced aluminum and silicon carbide filled magnesium, are also useful are anisotropic polymers such as liquid crystal polymers. 
     In constructing the rod, it is not necessary for all the elongated V section elements to be fabricated from the same material and, in fact, it can be advantageous in certain circumstances to use different materials having different mechanical properties. Thus, in the case where the rod is to be placed under load in only one bending direction, elongate V section elements of high compressive strength may he employed on the inside of the curve and elements of high tensile strength may be employed on the outside of the curve. This will minimize the weight of the rod shaft etc. and the quantity of materials required to produce a particular stiffness or action. 
     Additional strength characteristics may be provided by filling one or more of the cavities within the rod with one or more suitable fillers. Preferred fillers include expanded structural foams such as polyurethanes, polyvinylchloride, polyimide, polystyrenes and composites such as resinous mixtures of glass bubbles and microspheres, silicates, carbonates, chopped strand fibres and fibre whiskers. The filler may be placed into the cavities after the V section elements have been joined together or into the space between the legs of the V section element prior to joining. 
     To form a polygonal structure of 6 sides, a combination of 6 accurately machined composite V section elements and extending the full length of the element: The V section elements are glued together lengthwise with the open end of the V section element glued to one of the legs of the adjacent V section element with the apex of the V section element facing outwards. 
     An outer fibre/resin composite skin is then added by tape winding or filament winding or composite cloth wrapping around the tapered rod formed from the V section elements to give a structure similar to that above. Further strengthening of the hexagonal structure can be achieved by gluing a similar angled shaped object into the triangular hollows having the apex of this structure covering the outermost joint of the V section element. One leg of the structure being glued to the surface of the inner leg of the adjacent V section element. The other of the structure is glued to the inner surface of the V section element that forms the outer surface. These V shaped reinforcing structures can be of composite material, or aluminum, brass, steel or expanded structural foam etc. 
     The jointing together of the elongate V section elements may be achieved by the use of an adhesive which is compatible with the materials of the element; for instance, epoxy resin, or, in the case of some thermoplastics by the use of ultrasonic welding. 
     The present invention is now described with respect to the above Figures. In FIGS. 1,  2  and  3 , accurately machined elongate V section element  100  may be fabricated from a wide range of materials such as fibre reinforced plastics which include glass, carbon, polyimide and boron fibre in admixture with polyester, epoxy, phenol or thermoplastic resins. 
     In FIGS. 1 and 3 are shown accurately machined elongate V section reinforcing element  101  fabricated from composite material or metal, such as brass, aluminum, steel, titanium and metal composites, bonded to inside of outer leg of elongate V section element and the to the outer surface of the inner leg of the adjacent V section element, so that the reinforcing V section element covers the glued joint  102 . The radius  103  of reinforced V section structure  101  can be sharp or rounded depending on design and performance of product. The inner leg ends  104  of the elongate V sections  100  are intended to be glued or likewise secured together generally in axial securing zone  108 . FIG. 3 shows such securing. Extra laminates  105  of compatible material added to the outer surface of the V section element  100  depending on the requirements of the product. Cavity fill  106  such as expanded structural foam, polyurethanes, polyvinylchloride, polyimide, polystyrenes and composites such as resinous mixtures of glass bubbles and microspheres, silicates, chopped stressed fibres and fibre whiskers. 
     Tape winding or filament winding around structure not shown in full detail although the skilled person is informed by the disclosure herein of its advantages and application. 
     The present invention is now discussed with reference to the figures, whose reference numbers indicate substantially similar aspects of the figure when the same reference number is used in separate figures. With reference to FIG. 4, a first embodiment of the basic structural unit  400  is shown in cross section comprising a first adjacent shaft  401  and second adjacent shaft  402 . Shaft  401  comprises: 
     inner face  407 ′ of an outside facing solid side, 
     outer face  408 ′ of an outside facing solid side, 
     inner face  406 ′ of a joined polygon enclosed solid side, 
     outer face  403 ′ of a joined polygon enclosed solid side, 
     leg surface  404 ′ of a joined polygon enclosed solid side, 
     leg surface  405 ′ of a an outside facing solid side, and 
     longitudinal void  414 . 
     Shaft  402  comprises: 
     inner face  407  of an outside facing solid side, 
     outer face  408  of an outside facing solid side, 
     inner face  406  of a joined polygon enclosed solid side, 
     outer face  403  of a joined polygon enclosed solid side, 
     leg surface  404  of a joined polygon enclosed solid side, 
     leg surface  405  of an outside facing solid side, and 
     longitudinal void  413 . 
     Leg surfaces  404  and  405  are shown to be adapted to be roughly parallel with an outer face  403 ′, thereby having between them spaces  409  and  410  respectively. Spaces  409  and  410  are optionally separately bondingly closed as described in one of the several manners described in the Summary of the Invention. The leg surfaces of this first embodiment are preferably formed or machined to achieve an edge or face appropriate for force transmitting contact the outer face  403 ′ of the joined polygon enclosed solid side. This force transmitting abutment or connection is critical to the present invention. 
     With reference to FIG. 5, a second embodiment of the basic structural unit  500  is shown in cross section comprising a first adjacent shaft  501  and second adjacent shaft  502 . Shaft  501  comprises: 
     inner face  507 ′ of an outside facing solid side, 
     outer face  508 ′ of an outside facing solid side, 
     inner face  506 ′ of a joined polygon enclosed solid side, 
     outer face  503 ′ of a joined polygon enclosed solid side, 
     leg surface  504 ′ of a joined polygon enclosed solid side, 
     leg surface  505 ′ of an outside facing solid side, 
     leg extension  511 ′ of an outside facing solid side, and 
     leg extension  512 ′ of a joined polygon enclosed solid side. 
     Shaft  502  comprises: 
     inner face  507  of an outside facing solid side, 
     outer face  508  of an outside facing solid side, 
     inner face  506  of a joined polygon enclosed solid side, 
     outer face  503  of a joined polygon enclosed solid side, 
     leg surface  504  of a joined polygon enclosed solid side, 
     leg surface  505  of an outside facing solid side, 
     leg extension  511  of an outside facing solid side, and 
     leg extension  512  of a joined polygon enclosed solid side. 
     Leg surfaces  504  and  505  are shown to be adapted to be roughly parallel with an outer face  503 ′, thereby having between them spaces  509  and  510  respectively. Spaces  509  and  510  are optionally separately bondingly closed as described in one of the several manners described in the Summary of the Invention. The leg surfaces of this second embodiment are preferably formed or machined to achieve an edge or face appropriate for force transmitting contact the outer face  503 ′ of the joined polygon enclosed solid side by inward extension from the ends of an outside facing solid side and a joined polygon enclosed solid side. The leg extensions provide additional resistance to bending and twisting without obtaining the additional stiffness of a fully triangular shaft. 
     With reference to FIG. 6, a third embodiment of the basic structural unit  600  is shown in cross section comprising a first adjacent shaft  601  and second adjacent shaft  602 . Shaft  601  comprises: 
     inner face  607 ′ of an outside facing solid side, 
     outer face  608 ′ of an outside facing solid side, 
     inner face  606 ′ of a joined polygon enclosed solid side, 
     outer face  603 ′ of a joined polygon enclosed solid side, 
     leg surface  604 ′ of a joined polygon enclosed solid side, and 
     leg surface  605 ′ of an outside facing solid side, 
     leg extension  611 ′ of an outside facing solid side, and 
     leg extension  612 ′ of a joined polygon enclosed solid side. 
     Shaft  602  comprises: 
     inner face  607  of an outside facing solid side, 
     outer face  608  of an outside facing solid side, 
     inner face  606  of a joined polygon enclosed solid side, 
     outer face  603  of a joined polygon enclosed solid side, 
     leg surface  604  of an inside face of leg extension  611 , 
     leg surface  605  of an outside facing solid side, 
     leg surface  609 ′ of leg extension  611 , and 
     leg extension  611  of a joined polygon enclosed solid side. 
     Leg surface  605  is shown to be adapted to be roughly parallel with an outer face  503 ′, thereby having between them space  610 . Leg surface  604  is shown to be adapted to be roughly parallel with an leg surface  604 ′, thereby having between them space  609 . Shaft  601  has a joined polygon encloses solid side shorter than its outside facing solid side by about the thickness of leg extension  611 . Spaces  609  and  610  are optionally separately bondingly closed as described in one of the several manners described in the Summary of the Invention. The presentation of leg surface  609 ′ has a parallel form the force transmitting equivalent of leg surface  404 ′ of FIG.  1 . 
     It is clear from this disclosure that the bending and twisting forces on the basic structural unit of this third embodiment will be distributed substantially differently than those of the first embodiment. In a twisting motion, of the first embodiment spaces  409  or  410 , one space will tend to compress and the other will tend to separate. With the third embodiment in a twisting motion, of the third embodiment spaces  609  or  610 , when space  610  tends to compress, space  611  will also tend to compress. Alternately, when space  609  tends to separate, space  609  will tend to remain about the same with the abutment of the shorter solid side end against the vertex of the adjacent shaft solid side and leg extension. 
     With the above disclosure, it will apparent that the embodiments of the basic structural units of the present invention may be advantageously abutted against each other to obtain a larger variety of flexural characteristics. For example, outer face  403  of FIG. 1 may be joined against leg surfaces  605 ′ and  609 ′ of FIG. 6 to continue the circular build-up of the basic structural units into a joined polygonal shaft. FIGS. 7-10 show just such circular build-up assemblies for the three embodiments of the present invention. 
     FIG. 7 shows the shafts  401  and  402  of a unit  400  duplicated three times and continued in a circular build-up method to provide a single joined polygon shaft. Central axis bonding zone  411  shows a preferable zone in which to provide one of the methods of bonding together the free ends of the joined polygon enclosed solid sides. Outside seam bonding zone  412  shows a preferable zone in which to provide one of the methods of bonding together the leg surface of the outside facing solid side and the abutting vertex zone of the joined polygon enclosed solid side of the adjacent shaft. 
     FIG. 8 shows the shafts  501  and  502  of a unit  500  duplicated three times and continued in a circular build-up method to provide a single joined polygon shaft. Central axis bonding zone  514  shows a preferable zone in which to provide one of the methods of bonding together the free ends of the joined polygon enclosed solid sides. Outside seam bonding zone  513  shows a preferable zone in which to provide one of the methods of bonding together the leg surface of the outside facing solid side and the abutting vertex zone of the joined polygon enclosed solid side of the adjacent shaft. It is seen in the figures that the preferred second embodiment comprises filleting of at least the edges of the outer faces of the adjacent shafts. Where heavier materials, such as metals, alloys and reaction settable or heat formable sheets of polymers are used or where machining is preferably to be avoided on the leg surfaces, the forming or bending processes preferably leave filleted edges to improve the ease of fabrication and bonding. The outside face seams between the adjacent shafts present an area to which welded connections are more easily made. Zone  514  edge filleting creates a central void into which may be forced adhesive bonding means with reaction or heat setting action. 
     FIG. 9 shows the shafts  601  and  602  of a unit  600  duplicated three times and continued in a circular build-up method to provide a single joined polygon shaft. Central axis bonding zones  612  and  613  show a preferable zone in which to provide one of the methods of bonding together the free ends of the joined polygon enclosed solid sides. Outside seam bonding zone  614  shows a preferable zone in which to provide one of the methods of bonding together the leg surface of the outside facing solid side and the abutting vertex zone of the joined polygon enclosed solid side of the adjacent shaft. 
     FIG. 10 is an alternate embodiment of this first embodiment with a joined polygonal shaft comprising adjacent shafts  401 A and  402 A. Central axis bonding zone  411 A shows a preferable zone in which to provide one of the methods of bonding together the free ends of the joined polygon enclosed solid sides. Outside seam bonding zone  412 A shows a preferable zone in which to provide one of the methods of bonding together the leg surface of the outside facing solid side and the abutting vertex zone of the joined polygon enclosed solid side of the adjacent shaft. 
     It will be seen that joined polygonal shafts, as opposed to basic structural units, experience compression of, for example, space  410  shown in FIG. 1, regardless of the rotation of twisting force. In some embodiments, It is preferable to provide a more elastic and flexible bonding means for the central axis bonding zones than the outside seam bonding zones so that during twisting motion the free ends of the joined polygon enclosed sides may radially slightly expand without rupturing the bonding means while the bonding on the outside seam bonding zones is simple compressed. 
     In FIG. 12 are shown some of the several types of support means insertable into the longitudinal voids, such as voids  413  and  414  of the basic structural unit. Triangular support  415  and circular support  418  are shown in external side contact with the inside faces of a first adjacent shaft and the outside face of the joined polygon enclosed solid side. First and second nested adjacent shafts  416  and  417  are shown nested within the inside faces of the adjacent shafts of the first embodiment. Shaft  416  is shown and preferably has a solid side fully contact and engage at least an inside face of a first adjacent shaft and the outside face of the joined polygon enclosed solid side of a second adjacent shaft. Shaft  417  is preferably nested such that a solid side engages and fully contacts the remaining open inside face of the first adjacent shaft. The potential of additional nesting of smaller shafts of the types shown in this FIG. 11 will be apparent with this description. 
     FIG. 12 shows three embodiments of planar supports to an adjacent shaft of the first embodiment of the present invention. Inter-adjacent shaft planar insert  419  is adapted to be held fixed in spaces  409  and  410 , as those spaces are shown in FIG. 1, thus requiring a shortening  420  of the solid sides of adjacent shaft  402  to accommodate the insert thickness. Longitudinal void planar inserts  423  preferably abut just below the vertex on the inside face of an outside facing solid side of a first adjacent shaft and extend to abut at the other edge of the insert against the outer face of a joined polygon enclosed solid side of a second adjacent shaft immediately adjacent to the inside edge of the leg surface of the joined polygon enclosed solid side of the first adjacent shaft. An insert  423  extends the effective thickness of a joined polygon enclosed solid side with respect to force transmission from one adjacent shaft to another. External planar supports  422  preferably lie just above the outer face of the outside facing solid side of an adjacent shaft. Supports  422  provide greatest additional resistance to bending against bending in the direction parallel to the face of supports  422 . 
     Basic structural unit  400  with shafts  401  and  402  is shown multiplied in an enlarged structure in FIG.  13 . Space  424  indicate spaces in which the outside faces of solid sides longitudinally must abut with a minimum frequency to increase the size of several assembled basic structural units above the cross section size of a joined polygonal shaft, which has no such abutments. The wide distribution of compression, bending and twisting forces into such a structure provides a strong and lightweight structure. 
     The composition of the solid sides and insert means is limited only to those materials, alloys, composites and the like with sufficient longitudinal strength such that the skilled person would obtain with the above description effective resistance to bending, lateral compression and twisting within the temperature range required for effective operation of a device incorporating the basic structural unit of the present invention. It is another embodiment of the present invention that the composition of the solid sides and/or insert means comprise a high tensile strength weld mesh, effective for fabricating structures according to the present invention with a length of up to several hundred feet. FIG. 14 shows a first embodiment weld mesh  1400  whose resulting longitudinal void may appropriately be filled with structural carbon foam, and whose free ends may be extended in a manner to achieve adjacent shaft cross section shapes of the second and third embodiments. 
     It will be understood that the solid sides of the present invention are effectively so fabricated. Such adaptations as longitudinal, lateral or slanted slots, perforations, access openings and the like may be provided in the longitudinal surface of the solid surfaces of the present invention, albeit only to the extent that a desired flexural, compression or torsional characteristic is not substantively impaired by such piercing of the solid sides. 
     The above design options will sometimes present the skilled designer with considerable and wide ranges from which to choose appropriate apparatus and method modifications for the above examples. However, the objects of the present invention will still be obtained by that skilled designer applying such design options in an appropriate manner.