Abstract:
An aircraft deck support system includes horizontal deck support beams connected to the aircraft&#39;s frames. Each deck support beam has a plurality of machined, generally T-shaped supports. Each T-shaped support includes either a horizontal recess or a raised surface formed in a deck support beam upper chord and a U-shaped aperture formed in a beam web. The T-shaped support matably receives a cross-support beam attachment flange perpendicularly aligned with the deck support beams. Each cross-support beam includes a web perpendicularly connected at an upper end to the attachment flange, and a stiffening flange at a web lower end. Both the web and the stiffening flange are freely suspended within the U-shaped aperture of the T-shaped support. When joined, the cross-support beam seats on the T-shaped support allowing both the cross-support beam and the deck support beam to develop maximum bending moments at a reduced structural weight.

Description:
FIELD OF THE INVENTION 
     The present invention relates to deck support structures adapted for use in mobile platforms, and more specifically to an aircraft deck support structure for seating decks or cargo decks. 
     BACKGROUND OF THE INVENTION 
     An aircraft deck design typically comprises a plurality of deck support beams which run in an inboard/outboard direction and are attached at individual frames to the aircraft. The major components of each deck support beam are an upper chord which supports deck plating, and a lower chord generally arranged in parallel with the upper chord and separated from the upper chord by a web. At selected spaced intervals along each of the deck support beams, each of a plurality of I-shaped, J-shaped, C-shaped or H-shaped beams are positioned at about 90° angles to the deck support beams. For simplicity, the I-shaped, J-shaped, C-shaped or H-shaped beams will hereinafter be referred to as cross-support beams. In many aircraft designs, the cross-support beams are arranged in a fore/aft direction and partially support deck plating in either a passenger compartment or a cargo stowage compartment. The cross-support beams commonly have notches which receive locking rings used to lock-in and support seats in the passenger compartment or cargo container systems in the cargo stowage compartment. 
     In existing aircraft designs, aircraft designers used several concepts to connect the combination of the inboard/outboard running deck support beams and the cross-support beams. Each concept used to date has drawbacks. In the earliest concept, both a lower flange and web of the cross-support beam were cut to make the cross-support beam the equivalent of a pin joint at the connection to the deck support beam. The upper flange of the cross-support beam was supported by the upper chord of the deck support beam. Several drawbacks exist with this concept. By cutting the cross-support beam, its continuous moment carrying capacity is lost. To regain moment carrying capacity, hardware including brackets and fasteners were used to splice the cross-support beam to the deck support beam at each cross-support beam to deck support beam intersection. Both the time to build the deck and the weight of the deck system increase using this design. 
     Another concept used by aircraft designers for deck assembly required the deck support beam be cut to provide clearance for the cross-support beam. Similar to the concept of cutting the cross-support beam, hardware, including fasteners and angle brackets, are required to splice the cross-support beam to the deck support beam at each aperture location in order to regain the moment carrying capability of the deck support beam. This design also has several drawbacks. Some reinforcement of the deck support beam is normally required due to the structural strength lost at the clearance cut. Also, by requiring hardware to re-splice the beam at each intersection with a cross-support beam, the amount of time required to build the deck is increased. Moreover, the weight of the overall deck increases due to both the additional reinforcement and hardware. 
     In more recent aircraft designs, each cross-support beam is entirely supported on the upper surface of each deck support beam upper chord. No cuts in either the deck support beam or the cross-support beam are required. The full moment carrying capacity of both the deck support beam and the cross-support beam are developed. The drawback of this concept is that the combined vertical height of the deck support beam and cross-support beam reduces the overhead clearance (or usable compartment volume) in the particular compartment. If the deck support beam or cross-support beam vertical heights are reduced to improve overhead clearance, structural weight increases due to the reduced moment carrying capability of shallower structures. 
     A need therefore exists for a deck design for joining deck support beams and cross-support beams which maximizes overhead compartment space, reduces the amount of hardware required to assemble the deck system, and optimizes the moment carrying capacity of the combination of the cross-support beams and the deck support beams. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment of the present invention, a deck support beam having a discontinuous upper chord includes an aperture in the deck support beam web to provide clearance for a cross-support beam. An upper support flange of the cross-support beam spans the aperture in the upper chord of the deck support beam. A web and lower stiffening flange of the cross-support beam are suspended in the aperture of the deck support beam. The support flange of the cross-support beam structurally re-splices the upper chord of the deck support beam across the aperture using a plurality of mechanical fasteners. Only the plurality of fasteners is required to join the cross-support beam at each intersection with the deck support beam. The shape of the cross-support beam is also optimized to support the weight of the deck throughout the length of the cross-support beam by changing the geometry of the cross-support beam in each span between deck support beams. 
     The deck support beam of the present invention is formed by machining the desired configuration from a solid block of metal. Both an upper and a lower chord are formed having a beam web joining the upper to the lower chord. A plurality of vertical ribs are also machined into the intermediate web approximately perpendicular to the beam web. At predetermined vertical ribs one end of the rib is bifurcated, thus providing a clearance opening formed as a generally U-shaped aperture through the upper chord and a portion of the beam web of the deck support beam. Adjacent to each U-shaped aperture, either a horizontal recess or a raised surface is also machined into an outer face of the upper chord of the deck support beam. 
     The cross-support beams of the present invention are preferably formed as either I-shaped or J-shaped beams. Each cross-support beam includes an upper support flange formed as a wide flange to span each U-shaped aperture, and a web joining the upper support flange to a stiffening flange. The stiffening flange is narrower than the upper support flange to allow both the stiffening flange and the web to be suspended within the U-shaped aperture formed in the deck support beam. A plurality of mechanical fasteners is used to join each upper support flange of a cross-support beam to a selected horizontal recess or raised surface on the deck support beam, thereby splicing the deck support beam in the area where each U-shaped aperture is formed without requiring additional hardware such as brackets or angles. 
     The size and geometry of both the deck support beam and the cross-support beam of the present invention can vary depending upon the span length and the spacing of the deck support beams and the weight carried by the deck of the aircraft. The gage thickness of the chords of the deck support beam as well as the depth of the deck support beam can be varied to provide the weight and moment carrying capacity necessary for the individual deck. By varying the width of the support flange of each cross-support beam along its fore and aft length as well as varying the depth or thickness of its stiffening flange, the moment carrying capacity and weight of the cross-support beam are optimized. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1A is a perspective view of an aircraft known in the art having a plurality of deck support beams each supported by a sequential frame of the aircraft and a plurality of fore/aft running rails providing seat support; 
     FIG. 1B is an enlarged view from FIG. 1A of a typical intersection between a cross-support beam known in the art at its intersection with a deck support beam; 
     FIG. 2 is an elevation view looking forward showing a single deck support beam intersected by a plurality of cross-support beams of one embodiment the present invention; 
     FIG. 3 is a perspective view including a U-shaped aperture and horizontal recess formed adjacent to a selected vertical rib in a deck support beam of the present invention; 
     FIG. 4 is an enlarged side view of a portion of the deck support beam of FIG. 2, showing a cross-support beam support flange of the present invention seated in the horizontal recess of the deck support beam upper chord, and the web and stiffening flange of the cross-support beam suspended within the U-shaped aperture formed in the deck support beam web of the present invention; 
     FIG. 5 is a perspective view showing a partial section view of a cross-support beam intersecting with a deck support beam showing the features of the present invention; and 
     FIG. 6 is an enlarged side view of another embodiment of the present invention deck support beam of FIG. 2, showing a cross-support beam support flange of the present invention seated on a raised surface of the deck support beam upper chord, and the web and stiffening flange of the cross-support beam suspended within the U-shaped aperture formed in the deck support beam web of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     Referring to FIG. 1A, an aircraft  10  having a support structure known in the art is shown. The aircraft  10  support structure includes a plurality of frames  12 , a plurality of horizontally supported deck support beams  14 , and deck plating  16 . As known in the art, each deck support beam  14  is supported from one of the plurality of frames  12 . A pair of cross-support beams  18  are also shown. The number of cross-support beams  18  can vary depending upon the individual aircraft design. 
     Referring to FIG. 1B, an exploded view of a typical connection known in the art made between a cross-support beam  18  and a deck support beam  14  is shown. In the exemplary configuration shown, a portion of the deck support beam  14  is cut away providing an aperture  26  for at least the lower flange of the cross-support beam  18  to pass through. To structurally splice the deck support beam  14  together, support flanges  20  are mounted from the web of the deck support beam  14  and mechanically fastened to the cross-support beam  18 . In addition, a plurality of fasteners  22  are applied through the cross-support beam  18  to an upper surface of the deck support beam  14 . 
     Referring back to FIG. 1A, a plurality of seats  24  are shown mounted on the deck plating  16  and connectably fastened to the cross-support beam  18  using a plurality of clips (not shown) which are known in the art. A larger cross-support beam (not shown), similar to the cross-support beam  18  is substituted if the deck plating  16  and the deck support system is intended for cargo support rather than for passenger seating support. Minor changes to plate thicknesses, material and beam sizes are commonly made to incorporate the design shown in FIGS. 1A and 1B into a cargo storage deck. 
     Referring now to FIG. 2, a deck support beam  30  according to a preferred embodiment of the present invention is shown. The deck support beam  30  includes an upper chord  32 , joined by a plurality of ribs  33  to a lower chord  34 . In this embodiment, the deck support beam  30  is machined from a single block of metal, and a beam web  36  is provided between the upper chord  32  and the lower chord  34  together with the plurality of ribs  33 . A plurality of generally T-shaped supports  38  are provided in each deck support beam  30 . Each T-shaped support  38  is provided in a location where a cross-support beam  40  is supported. The cross-support beam  40  seats on the upper chord  32  and a portion of the cross-support beam  40  is suspended within the T-shaped support  38  as will be described in further detail below. As noted herein, a plurality of beam shapes can be used for the cross-support beams  40 , including I-shaped beams, C-shaped beams, J-shaped beams and H-shaped beams. In one preferred embodiment shown in FIGS. 2,  4 , and  5 , a generally I-shaped beam is shown. 
     As known in the art, a plurality of deck support beams  30  are provided at one or more predetermined spacing(s). The spacing(s) is/are dependent upon a fore/aft distance between each of a plurality of frames  42  of the aircraft. The plurality of deck support beams  30  are arranged approximately parallel to each other. Each deck support beam  30  is typically mechanically fastened to one of the plurality of frames  42  and can also be supported by one or more vertical stanchions  44 . 
     Referring now to FIG. 3, the machined details of the T-shaped support  38  are shown in greater detail. Each upper chord  32  and each lower chord  34  are formed preferably by machining material from a solid block of metal. When forming the deck support beam  30 , a plurality of ribs  33  are formed. Each rib  33  is formed approximately perpendicular to the beam web  36 . The beam web  36  is approximately centrally located along a chord width B. At periodic locations along the upper chord  32 , each of a plurality of horizontal recesses  46  are machined or otherwise formed, each having a horizontal recess width D. The horizontal recess width D can vary depending upon the deck application. In one preferred embodiment a nominal dimension for the horizontal recess width D is about 13.7 cm (5.4 in). The horizontal recess  46  opens on an outside facing side of the upper chord  32 , i.e., opposite from the beam web  36  side of the upper chord  32 . 
     Bisecting each horizontal recess  46  is a U-shaped aperture  48 . Each U-shaped aperture  48  is formed in one of a plurality of preselected ribs  50  each having a bifurcated end  52 . A plurality of fastener apertures  54  are provided in the horizontal recess  46  on both sides of the U-shaped aperture  48 . Each fastener aperture  54  receives a mechanical fastener shown in greater detail in FIG. 4 to mechanically join the cross-support beam  40  to the horizontal recess  46 . 
     The deck support beam  30  has a support beam height C forming a vertical envelope which will vary depending upon the type of deck design between about 7.6 cm (3.0 in) to about 27.9 cm (11 in) in an exemplary commercial aircraft design. The chord width B can vary in the exemplary embodiment shown between about 5.08 cm (2 in) to about 5.33 cm (2.1 in). A total aperture depth E has an exemplary dimension of about 5.9 cm (2⅓ in) in the embodiment shown. The aperture depth E can range from about 20% to about 50% of the total support beam height C. A chord thickness F is also shown. The chord thickness F can vary depending upon the deck design load, the free span between deck support beam  30  vertical supports and total height of the deck support beam  30 . For the upper chord  32 , the chord thickness F ranges between about 0.28 mm (0.11 in) to about 0.46 mm (0.18 in) for the exemplary embodiment shown. The lower chord  34  thickness is about 0.76 cm (0.30 in) in the exemplary embodiment shown. 
     Referring to FIG. 4, the cross-support beam  40  is shown seated in the horizontal recess  46 . Each cross-support beam  40  includes a support flange  56 , a web  58  and a stiffening flange  60 . The support flange  56  seats within the horizontal recess  46  such that a support flange upper face  62  is in co-planer alignment on a plane A with a chord upper face  64 . The web  58  and the stiffening flange  60  of the cross-support beam  40  are freely suspended within the U-shaped aperture  48 . 
     Each preselected rib  50  includes the bifurcated end  52  having the U-shaped aperture  48  machined therein. FIG. 4 provides an alternate embodiment from that shown in FIG. 3, in that the U-shaped aperture  48  in FIG. 4 is shown having a generally angular shaped lower surface, wherein the U-shaped aperture  48  shown in FIG. 3 has a rounded bottom surface. The cross-support beam  40  has a support flange thickness G and a support flange width H. The support flange thickness G is sized appropriately for the deck support beam upper chord vertical load. Therefore, in the exemplary embodiment shown, the support flange thickness G is about 0.43 cm (0.17 in). In the exemplary embodiment, the support flange width H ranges from preferably about 12.7 cm (5.0 in) to about 13.5 cm (5.3 in). This allows the support flange  56  to fully seat within the horizontal recess  46 . Both the support flange thickness G and the support flange width H can vary depending upon the strength and geometry of the desired deck configuration. 
     In a preferred embodiment, the cross-support beam  40  further includes a C-shaped channel  66 . The C-shaped channel  66  includes a pair of flanges  68  and  70 , respectively. The flanges  68  and  70  provide for a vertical opening  1 . The C-shaped channel  66 , together with the vertical opening  1 , provide a channel forming either a seat track or a cargo track within which an aircraft seating assembly (similar to the seats  24  shown in FIG. 1) is locked, or a stowage container system (not shown) is located and locked as known in the art. The support flange  56  is mechanically connected to the horizontal recess  46  on both sides of the U-shaped aperture  48  using a plurality of fasteners  72 . Each of the plurality of fasteners  72  are positioned within the fastener apertures  54  shown in both FIG.  4  and in FIG.  3 . The combination of the support flange  56  and the plurality of fasteners  72  provide the splicing connection spanning each horizontal recess  46  formed in the upper chord  32 . 
     Referring now to FIG. 5, a partial configuration of one preferred embodiment of the present invention is shown. A cross-support beam  40  is shown in position approximately perpendicular to a deck support beam  30 . The cross-support beam  40  has a support flange maximum width K adjacent to the horizontal recess  46 , to provide a greater seating surface for the plurality of fasteners  72  shown in FIG.  4 . Between each successive pair of deck support beams  30 , a support flange minimum width L and thickness G (shown in Figure 4) are used. The support flange minimum width L is provided to reduce the overall weight of a cross-support beam  40  because the flange width does not add significantly to the vertical moment carrying capacity of the cross-support beam at mid-span between adjacent deck support beams  30 . 
     At each intersection between a cross-support beam  40  and a U-shaped aperture  48  shown in FIG. 4, a stiffening flange minimum vertical cross section M is used. The vertical moment of the cross-support beam at its junction with the deck support beam is carried in part by the support flange maximum width K, therefore allowing the stiffening flange minimum vertical cross section M. The stiffening flange  60  deepens between each successive deck support beam  30  such that a stiffening flange maximum vertical cross section N is used at the mid-span between each successive deck support beam  30 . The stiffening flange maximum vertical cross section N corresponds to the cross-support beam  40  mid-span location where the vertical moment on the cross-support beam  40  from the deck load is greatest, i.e., between each pair of deck support beams  30  where the vertical support from the deck support beams  30  is lowest. 
     FIG. 5 also shows a plurality of notches  74 . The notches  74  are provided to locate and lock-in a seat or cargo locking ring (not shown). The notches  74  and locking rings are well known in the art and will not be discussed further herein. 
     Referring back to FIGS. 2 through 4, the vertical height of the deck support beam  30  can vary to support different deck loads. The support beam height C (identified in FIG. 3) can vary as shown in FIG. 2 along the horizontal length of each deck support beam  30 . In the embodiment shown, each upper chord  32  of each deck support beam  30  identified in FIG. 4 is approximately aligned with the plane A to provide a level deck support surface, requiring the lower chord  34  to change elevation to accommodate a changing support beam height C. 
     Referring to FIG. 6, another preferred embodiment of the present invention provides the T-shaped support  38  as a raised surface  76  bisected by a U-shaped aperture  78 . The U-shaped aperture  78  is similar in shape and function to the U-shaped aperture  48 . In this embodiment the support flange  56  of the cross-support beam  40  is raised above the plane A of the chord upper face  64  to provide corrosion protection between the cross-support beam  40  and the chord upper face  64  by allowing moisture runoff along a pair of tapered shoulders  80 . The support flange upper face  62  is raised to a support flange height P. The support flange height P is approximately 1.2 cm (0.5 in) above the plane A. Deck plating (not shown) will be supported by the support flange upper face  62  above the chord upper face  64  which will provide additional corrosion protection by separating the deck plating from the chord upper face  64 . The U-shaped aperture  78  is formed from a preselected rib  82  which is similar to the preselected rib  50 . 
     Referring back to FIGS. 1A,  4  and  6 , the deck plating  16 , known in the art, is typically positioned adjacent to the outboard (i.e., outside vertical) faces of each C-shaped channel  66 . Each C-shaped channel  66  is therefore exposed after deck plating installation such that the locking rings (not shown, but discussed above) can be applied in each of the notches  74  to retain either the exemplary arrangement of seats  24  shown in FIG. 1B or a cargo container system (not shown). 
     In a preferred embodiment of the present invention, each deck support beam  30  is manufactured by machining the features of the beam from a single piece of aluminum material. However, it will be appreciated that any metal having mechanical properties and weight characteristics suitable for aircraft use can be used for the deck support beam. With appropriate controls during forming/machining, laminate or composite materials can also be used for the deck support beams of the present invention. The cross-support beams of the present invention are also preferably formed from an aluminum material, however alternate materials noted above can also be substituted. Fasteners  72  can be selected from a variety of mechanical fastener types including bolts, studs and rivets. Other methods of building the deck support beam can be used, including weld buildup of the beam from individual parts. Apertures (similar to those shown in FIG. 1) can also be provided within each beam web  36  to reduce deck support beam weight or to provide through-passage of equipment including electrical wire-ways, piping and structure. These apertures are known in the art and will therefore not be described further herein. 
     The stiffening flange minimum vertical cross section M, in a preferred embodiment of the present invention, is preferably about 0.48 cm (0.19 in). The stiffening flange maximum vertical cross section N, in a preferred embodiment of the present invention, is preferably about 0.86 cm (0.34 in). The stiffening flange cross section dimensions can vary, as well as a thickness of the web  58 , depending upon the load to be carried by the cross-support beam  40 , the size and geometry of the deck support beam  30 , and the material selected for both components. 
     The aircraft floor design of the present invention offers several advantages. By initially machining the U-shaped aperture  48  of the present invention into the deck support beam  30 , the cross-support beam  40  can be supported by the deck support beam without making cuts in the beam web  36  or the cross-support beam  40 . Additional fasteners and support flanges known in the art that are used to re-splice the cuts made in either the deck support beam or the cross-support beam are eliminated by the present invention. By providing a T-shaped support in the upper chord of the deck support beam, the support flange of the cross-support beam seats on the support, allowing deck plating to be butted adjacent to the C-shaped channel of the cross-support beam. By varying a width of the support flange of the cross-support beam and a vertical cross section of its stiffening flange, vertical load support provided by the deck support beam is included in the cross-support beam design to locally reduce stiffening flange cross section, while the increased vertical support necessary at mid-span between individual deck support beams is also provided. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. Variations can include use of the support structure of the present invention in non-aircraft applications, including other vehicle types, ships and movable structures where space or weight savings can be realized.