Patent Publication Number: US-11377849-B2

Title: Composite panel

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 16/224,702 filed on Dec. 18, 2018 which issues as U.S. Pat. No. 10,612,237 on Apr. 7, 2020. Each of the aforementioned patent applications, and any applications related thereto, is herein incorporated by reference in their entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable to this application. 
     BACKGROUND 
     Field 
     Example embodiments in general relate to a composite panel for replacing multi-part assemblies, such as floor boards or other parts of RVs, buses, aircraft, boats, etc. 
     Related Art 
     Any discussion of the related art throughout the specification should in no way be considered as an admission that such related art is widely known or forms part of common general knowledge in the field. 
     Structural panels have been in use for many years in constructing floor, ceiling, and wall panels for vehicles such as RVs, buses, tractor-trailers, boats, trains, and aircraft. 
     In the past, such panels have been manufactured from multiple components and fastened or bonded together to add strength, weather resistance, and other characteristics only where needed to save weight and cost. For example, it has been common in manufacturing RV floors to start with a bottom layer of plywood, onto which a series of welded tubes are placed in a particular pattern to allow holes to be drilled in the tubes to secure items such as cabinets, appliances, fixtures, etc. with screws or other fasteners. 
     Styrofoam has also typically been used in such panels to fill the open space between the welded tubes and to provide some additional support for a top plywood sheet that was placed on top of the welded tubes and Styrofoam. The top sheet was then fastened to the bottom sheet and the tubes. Next, the bottom sheet, which may be exposed to the road and weather, was coated to seal the floor system from moisture, dirt, etc. 
     Such RV floors may be costly, heavy and also require multiple assembly steps and a relatively high number of components, fasteners, etc., to be kept in inventory. Further, these panels are obviously not inherently water or weather resistant, and so must be treated to resist the elements, and they are still susceptible to interior parts deteriorating and possibly failing if water or dirt does eventually penetrate the exterior surfaces. 
     SUMMARY 
     An example embodiment is directed to a composite panel. The composite panel generally includes a first panel surface and a second panel surface, and at least one internal preform positioned within the panel between the first panel surface and the second panel surface, wherein the at least one internal preform is spaced apart from the first panel surface and the second panel surface and is positioned to at least partially create a patterned structural portion. The patterned structural portion comprises a cured composite matrix material that substantially surrounds the internal preform on at least two sides. The patterned structural portion is formed in part by a maze of voids in the mold cavity, and is generally stronger than the part of the panel system where the internal preform is positioned. The internal preform is generally very low density compared to the composite matrix material. 
     In another example embodiment of the composite panel, the patterned structural portion substantially surrounds the internal preform on at least four sides, and may surround it on six sides. The composite panel may further include a reinforcing layer (such as fiberglass scrim or other material) proximate the first panel surface, and may also include a second reinforcing layer proximate the second panel surface. In another example embodiment where a high quality finish is required, the composite panel may further include a gel coat layer over the first panel surface or the second panel surface. 
     In still another example embodiment, the first panel surface and the second panel surface of the composite panel are substantially coplanar. Further, the at least one internal preform may have two surfaces that are substantially coplanar with the first panel surface and the second panel surface. The composite panel may further comprise a plurality of spacers positioned between the internal preform and the first panel surface and between the internal preform and the second panel surface, and thus help to maintain the position of the internal preform within the composite panel. 
     In another example embodiment, the composite panel may include a reinforcing element between the first panel surface and the second panel surface, away from the internal preform, wherein the reinforcing element is substantially surrounded by the patterned structural portion in at least one plane. 
     In still another example embodiment, the internal preform of the composite panel comprises a plurality of “chimneys” or channels adapted to allow uncured composite matrix material to flow from one side of the internal preform to the opposite side of the internal preform when the matrix material is infused into the mold. Further, the composite panel can include a plurality of internal preforms to form a complex structure with multiple patterned structural areas. Optionally, the patterned structural portion may comprise at least one substantially rectangular shape, although many shapes and sizes are possible. 
     Another example embodiment is directed to a method of making a composite panel in a closed mold. The method may include providing a mold bottom having a first surface, providing a mold top having a second surface, and positioning a mold body on the mold bottom. Next, reinforcing material, such as fiberglass scrim, can be positioned on the first surface of the mold bottom. One or more spacers can then be positioned on the reinforcing material to support an internal preform and to space the internal preform apart from the first surface. 
     Next, an internal preform is placed on the one or more spacers in a position to create a patterned structural region comprising void areas in the mold, and then positioning reinforcing material (such as fiberglass scrim) proximate the second surface of the mold top. After the reinforcing material is installed, the mold top may be placed on the mold body, creating an enclosed cavity. In this example embodiment, the mold can then be filled with a composite matrix material, wherein the composite matrix material flows around the internal preform and the first spacer and substantially fills the void areas in the mold. The composite matrix material is then allowed to cure, forming a patterned structural region around the internal preform. 
     In another example embodiment, one or more spacers can also be positioned between the internal preform and the reinforcing material on the mold top. The spacers may be pre-cured composite matrix material of the same type that is used to fill the mold, to better create a chemical and mechanical bond between the materials. 
     Another example embodiment of the method includes positioning a reinforcing element having a first thickness within the void areas in the mold, which may be used to provide high strength areas of the panel where heavy components may be attached with fasteners. For example, such components may be bolted to the panel, with the bolt extending through the reinforcing element. 
     In a further example embodiment of the method, filling the mold comprises pumping composite material into the mold under pressure. In addition, filling the mold may further comprise creating a vacuum within the mold to draw the uncured material into the mold. The method may further comprise applying a layer of gel coat to the mold bottom prior to positioning the reinforcing material on the first surface of the mold bottom, to produce panels with a high quality exterior finish. 
     There has thus been outlined, rather broadly, some of the embodiments of the composite panel in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional embodiments of the composite panel that will be described hereinafter and that will form the subject matter of the claims appended hereto. In this respect, before explaining at least one embodiment of the composite panel in detail, it is to be understood that the composite panel is not limited in its application to the details of construction or to the arrangements of the components set forth in the following description or illustrated in the drawings. The composite panel is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will become more fully understood from the detailed description given herein below and the accompanying drawings, wherein like elements are represented by like reference characters, which are given by way of illustration only and thus are not limitative of the example embodiments herein. 
         FIG. 1  is a perspective view of a composite panel in accordance with an example embodiment. 
         FIG. 2  is a front view of a composite panel in accordance with an example embodiment. 
         FIG. 3  is a sectional view of a composite panel in accordance with an example embodiment. 
         FIG. 4  is an alternative sectional view of a composite panel in accordance with an example embodiment. 
         FIG. 5  is a floorplan for which a composite panel in accordance with an example embodiment can be used. 
         FIG. 6  is a perspective view of a mold body usable for making a composite panel in accordance with an example embodiment. 
         FIG. 7  is a perspective view of a mold body with a reinforcing layer in place, usable for making a composite panel in accordance with an example embodiment. 
         FIG. 8  is another perspective view of a mold body with a reinforcing layer and internal preforms in place, usable for making a composite panel in accordance with an example embodiment. 
         FIG. 9  is a perspective view of a mold top with a reinforcing layer in place, usable for making a composite panel in accordance with an example embodiment. 
         FIG. 10  is a perspective view of a mold bottom, mold body, and mold top in place, usable for making a composite panel in accordance with an example embodiment. 
         FIG. 11  is a perspective view of an assembled, closed mold body showing tubing for infusing composite matrix material into the mold, usable for making a composite panel in accordance with an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A. Overview. 
     An example panel system generally comprises a composite panel  10  having lightweight internal preforms  20  that create a patterned structural portion  30  of the panel  10 . The composite panel  10  has a first panel surface  18  and a second panel surface  19 , and at least one internal preform  20  positioned within the composite panel between the first panel surface  18  and the second panel surface  19 . The internal preforms  20  may be spaced apart from the first panel surface and the second panel surface to create a composite “skin” or layer of the panel  10 . The internal preforms  20  are positioned to at least partially create a patterned structural portion  30  that is generally stronger than the portion of the panel where the internal preforms  20  are located. The patterned extra-strength areas are suitable for placement of heavy fixtures, furniture, etc., as well as fasteners to hold them in place, depending on the application for which the panel  10  is used. 
     The patterned structural portion  30  comprises a cured composite matrix material  32  that substantially surrounds the internal preforms  20  on at least two sides, and can surround them on all sides, as required. The patterned structural portion  30  is formed in part by a maze of voids in the mold cavity, and is generally stronger than the part of the panel system where the internal preform is positioned. The internal preforms  20  are generally very low-density material compared to the composite matrix material. 
     The composite panel system may further include a reinforcing layer  14  (such as fiberglass scrim or other reinforcing material) near the first panel surface  18 , and may also include a second reinforcing layer near the second panel surface  19 . In applications where a high-quality exterior finish is required, the panel system may optionally include a gelcoat layer  16  over the first panel surface  18  or the second panel surface  19 . 
     The first panel surface  18  and the second panel surface  19  of the panel  10  may be substantially coplanar, for use as floor or wall panels, or even as boat transoms, to name just a few possible examples. Other shapes are possible as well. For example, the manufacturing process and components disclosed here could even be used to create spheres and other shapes. Further, the internal preforms  20  may also have two surfaces that are substantially coplanar with the first panel surface  18  and the second panel surface  19 . The panel system may further include one or more spacers  40  positioned between the internal preforms  20  and the first panel surface  18  and between the internal preforms  20  and the second panel surface  19 , and thus help to maintain the position of the internal preform within the panel during the closed molding process, or any other process by which the panels are made. 
     In addition to the basic panel  10  shown in  FIG. 1 , the panel system may also include a reinforcing element  12  between the first panel surface and the second panel surface, away from the internal preform, wherein the reinforcing element  12  is substantially surrounded by the patterned structural portion  30  in at least one plane. 
     In still another example embodiment, the internal preform  20  of the panel  10  comprises a plurality of “chimneys” or channels  28  adapted to allow uncured composite matrix material  32  to flow from one side of the internal preform  20  to the opposite side when the matrix material is infused into the mold  50 . Further, the panel  10  can include a plurality of internal preforms  20  to form a complex patterned structural portion  30 . Optionally, the patterned structural portion  30  may comprise at least one substantially rectangular shape, although many shapes and sizes are possible. 
     Another example embodiment is directed to a method of making a composite panel  10  in a closed mold  50 , or alternatively, in an open mold. The method may include providing a mold bottom  51 , providing a mold top  55 , and positioning a mold body  52  on the mold bottom. Next, reinforcing material, such as fiberglass scrim, can be positioned on the mold bottom  51 . One or more spacers  40  can then be positioned on the reinforcing layer  14  to support an internal preform  20  and to space the internal preform  20  apart from the first surface  18  of the panel. 
     Next, an internal preform  20  is placed on the one or more spacers in a position to create a patterned structural portion  30  corresponding to void areas in the mold, and then positioning another layer of reinforcing material (such as fiberglass scrim) proximate the mold top. After the reinforcing layer  14  is in place, the mold top  55  may be placed on the mold body  52 , creating a substantially enclosed cavity. In this example embodiment, the mold  50  can then be filled with a composite core matrix/resin material  32 , wherein the composite matrix material flows around the internal preform(s)  20  and the first spacer  40  and substantially fills the void areas in the mold  50 . The composite matrix material  32  is then allowed to cure, forming a patterned structural region  30  around the internal preform  20 . 
     In another example embodiment, one or more spacers  40  can also be positioned between the internal preform  20  and the reinforcing layer  14  on the mold top. The spacers  40  may be pre-cured composite matrix material of the same type that is used to fill the mold, to better create a chemical and mechanical bond between the materials. 
     Another example embodiment of the method includes positioning a reinforcing element  12  within the void areas in the mold, which may be used to provide high-strength areas of the panel where heavy components may be attached with fasteners. For example, such components may be bolted to the panel, with the bolt extending through the reinforcing element. 
     In a further example embodiment of the method, filling the mold comprises filling the mold with composite matrix material  32 . For example, the material can be pumped into the mold  50  under pressure. In addition, filling the mold may further comprise creating a vacuum within the mold  50  to draw the uncured material  32  into the mold. The method may further comprise applying a layer of gelcoat to the mold bottom prior to positioning the reinforcing layer on the mold bottom, to produce panels with a high quality exterior finish. 
     B. Panel. 
       FIG. 1  illustrates a lightweight panel  10  comprising two lightweight internal preforms  20  surrounded by cured composite matrix material  32 , which forms a patterned structural portion  30 . For illustration purposes,  FIG. 1  shows a cutaway view panel  10  so that the internal preforms are visible. An actual finished panel  10  will appear to be simply a solid composite panel, but will be much lighter in weight, as described herein. Internally, a panel  10  may also include high strength reinforcing elements  12  for supporting fasteners, such as nuts and bolts, etc., as shown in  FIG. 4 . The reinforcing elements  12  may be made of virtually any structural material capable of being imbedded in the panels, such as wood, cured resin, or preformed composite materials. The reinforcing elements  12  may be used, for example, where very high strength is required, such as mounting motors on boat transoms, as well as other applications. 
     As shown in  FIGS. 3 and 4 , as with conventional panels, the panels  10  of the example embodiments may include a reinforcing layer  14  near one or both panel surfaces  18  and  19 . For example, the reinforcing layers  14  may comprise fiberglass scrim. When the composite core matrix material  32  surrounds the reinforcing layers and is subsequently cured, a composite panel  10  is formed, albeit one with internal regions with lower density than a panel made in a conventional way, with a continuous cured matrix material and uniform density throughout. 
     C. Internal Preform. 
     To help reduce the overall weight of the composite panel, one or more internal preforms  20  may be used, as best shown in  FIGS. 1 and 2 . The internal preforms can be made from urethane foam, Styrofoam, etc. For example, urethane foam boards with about the same density of Styrofoam can provide a good chemical and mechanical bond to the composite matrix material that surrounds the preforms  20 . As an example of the weight savings that may be achieved, the internal preforms may have a density that is only about ten percent of the density of the surrounding composite matrix material, which provides strength where needed, but is also heavier than the internal preforms  20 . 
     As shown in  FIG. 2 , any number of internal preforms  20  may be used to create a pattern of lightweight portions and stronger patterned structural portions  30  of the panels  10 . As also shown, the internal preforms  20  may be rectangular, substantially board-shaped components with surfaces that are or may be coplanar with the surfaces of the panels, although very complex shapes are also possible, and it is not even necessary that the internal preforms are flat, or have parallel sides. 
     When the internal preforms  20  are shaped as shown in  FIGS. 1 and 2 , they may include a first preform side  22 , a second preform side  24 , and a perimeter  26 . In any shape, they may also include multiple “chimneys” or channels  28 . The chimneys  28  are useful when the panels are being formed, as they allow composite matrix material to flow from one side of the panel to the other, and thus aid in ensuring that the matrix material  32  flows from one side of the preform to the other during the molding process. 
     The first preform side  22  may face panel surface  18 , and the second preform side  24  may face panel surface  19 , while cured composite matrix material  32  fills the space between the internal preform  20  and the outer surfaces  18  and  19  of the panel  10 . 
     D. Patterned Structural Portion. 
     As best shown in  FIGS. 1 and 2 , by using molding techniques but with extremely lightweight internal preforms  20  held in place during the molding process, a very lightweight composite panel can be formed. However, the lightweight panels are not merely placed wherever they will fit, but are instead shaped and placed accurately so that the remaining portion of the panel  10  will comprise a patterned structural portion  30 . For example,  FIG. 2  shows, in simplified form, patterned structural portion  30  in the general shape of a rectangle surrounding two squares (formed by the internal preforms) that do not make up part of the patterned structural portion  30 . 
     In the example embodiment of  FIG. 2 , if the panel were used as a floorboard (or transom) in a boat, mobile home, or recreational vehicle, for example, the preforms  20  might represent areas where high relative strength is not required, such as a portion of the floor with nothing mounted or supported above it. In contrast, the patterned structural portion  30  may represent a portion of the floor where more strength is required, such as mounting an appliance or piece of equipment. Potential fastener locations are also shown in  FIG. 2 . The patterned structural portions of the panels  10  can be used to receive fasteners to hold down appliances or walls, in addition to supporting greater weights than would be desirable for the lightweight portions formed by the internal preforms  20 . 
     The patterned structural portion  30  of panel  10  can have a highly complex shape, and may be made using, for example, a closed-mold process where a composite core matrix/resin material is pumped into a mold that already has the internal preforms  20  held in place or positioned as needed.  FIG. 2  shows a simplified pattern for illustration purposes, while  FIG. 5  illustrates a much more complex pattern of the type that is possible. As shown in  FIG. 5 , the patterned structural portion can replicate a frame constructed with wood, metal, or other materials, but can be made from the composite matrix/resin materials and internal preforms as described herein. In  FIG. 5 , the patterned structural portion  30  appears as the thinner elements that make up the pattern, similar to wooden studs in a stud wall. 
     In some example embodiments, the composite core matrix/resin material that comprises the patterned structural portion  30  may comprise one or more hollow or solid microsphere discontinuous portions disposed in a continuous encapsulating resin. In certain embodiments, the hollow or solid microspheres are selected from the group consisting of plastic microspheres, glass microspheres, ceramic microspheres, polyvinyl chloride (PVC) microspheres, acrylic microspheres, and any combinations thereof. 
     Hollow plastic microspheres are small spherical plastic particles. The microspheres consist of a polymer shell encapsulating a gas. When the gas inside the shell is heated, it increases its pressure and the thermoplastic shell softens, resulting in a dramatic increase in the volume of the microspheres. In certain embodiments, when fully expanded, the volume of the microspheres increases more than about 40 times. Glass microspheres are microscopic spheres of glass manufactured for a wide variety of uses in research, medicine, consumer goods and various industries. 
     Glass microspheres are usually between 1 and 1000 micrometers in diameter, although the sizes can range from 100 nanometers to 5 millimeters in diameter. Hollow glass microspheres, sometimes termed microballoons or glass bubbles, have diameters ranging from 10 to 300 micrometers. The use of hollow microspheres to form the patterned structural portion  30 , as well as the thinner layers above and below the internal preforms, further reduces density and improves the thermal and acoustic insulation of the panels, while increasing the relative stiffness of the original polymer. 
     E. Operation and Construction of Preferred Embodiment. 
     In use, the panel  10  is first created in a closed mold  50 , such as the mold shown in  FIG. 6 . The mold comprises a mold body  52  that rests on a mold bottom  51 . The mold body  52  may be made of silicone or similar material to aid in removing the cured panels from the mold, since many matrix materials will not adhere to the silicone. Initially, a reinforcing layer  14 , such as fiberglass scrim, is installed in the portion of the mold in which the panel will be formed, as shown in  FIG. 7 . Next, multiple spacers  40  are installed or positioned where the internal preforms  20  are to be placed. The internal preforms  20  serve the purpose of holding the internal preforms  20  away from what will be the surface of the finished panel, thus creating a layer of cured composite matrix/resin material  32  between the internal preforms  20  and the outer surfaces of the panel  10 . Because of the spacers  40 , the layers thus formed will have a relatively uniform thickness. The spacers  40  may be used on one or both sides of the internal preforms  20 . As shown in  FIG. 3 , the panel  10  thus includes a first layer portion  34  and a second layer portion  36 , which are formed at the same time, and from the same material, as the patterned structural portion  30  that flows into the mold  50 . 
     The spacers may be made by molding a flat sheet out of the same or a similar matrix material that will be used to form panel  10 , thus allowing for a strong chemical and mechanical bond between the spacers  40  and the layers formed by the matrix material. Once such a flat sheet is formed and cured, the spacers may be made by scoring the sheet and separating the spacers. 
     As is known, the reinforcing layer  14  adds strength to the panels, as with many composite construction techniques where a matrix material surrounds and encapsulates a reinforcing material. 
     After the first set of spacers  40  are positioned, as shown in  FIG. 7 , the internal preforms  20  are positioned on the spacers  40  so as to create a “maze” of voids where the matrix material  32  will be infused into the mold  50  to create the patterned structural portion  30 . In the illustrative pattern of  FIG. 8 , the patterned structural portion  30  is in the shape of a generally rectangular frame with a crossbar. Next, another set of spacers  40  are placed on top of the internal preforms  20 , as shown in  FIG. 8 .  FIG. 3  also shows, in cross-section, the resulting internal features of the panel  10  that is thus formed. 
     Next, another reinforcing layer  14  is installed on a mold top  55 , which may be a glass top to allow users to view the process and ensure quality. Alternatively, the second reinforcing layer may simply be positioned between the internal preform or spacers and the mold top  55 .  FIG. 9  illustrates an example embodiment of fiberglass scrim installed on a mold top  55  prior to placement on the mold body  52 . 
     Next, the mold top  55  is placed on the mold body  52  with the other reinforcing layer  14 , spacers  40 , and internal preforms  20  placed and positioned as needed to form a panel  10  with a patterned structural portion  30  of the desired shape, as shown in  FIGS. 10 and 11 . 
     As noted above, the patterned structural portions  30  may be significantly stronger than the panel portions that include the internal preforms  20 , which are extremely light and serve to help form the patterned structural portions  30  by forming a maze or void pattern where composite matrix material can flow during the closed mold process. 
     When the uncured composite core matrix material is introduced into the mold (for example, infused into the mold by a supply tube  56  coupled to infusion port  53 ), it flows into the voids in the mold, and may be aided in flow by a vacuum tube connected to vacuum port  54  at the end of the mold body opposite the infusion port  53 . In addition, the flow of the composite matrix material can be improved by the chimneys  28  in internal preforms  20 , which allow the matrix material to flow from one side of the preform to another, such as from the bottom to the top. 
     Thus, the uncured composite matrix material can flow within the mold to all the spaces/voids not occupied by other structures within the panel  10 . The composite matrix material will later cure to form a bottom sheet, the patterned structural portion, and a top sheet. The other structures that may be in the panels  10  are best shown in  FIG. 4 , and include a reinforcing element  12 , reinforcing layer  14 , internal preform  20 , and spacers  40 . 
     When panels  10  are formed as shown in  FIG. 3  (although other configurations are possible), the outer surfaces of the panel are substantially coplanar with the surfaces of the internal preforms  20 , which are also panel shaped. Due to the spacers  40  and the mold shape, the composite core matrix material will form sheets or layer portions between the outer surfaces of the panel and the internal preforms, so that from the outside, the panels appear to be made as a single, unitary structure that does not reveal the internal differences shown in  FIGS. 3 and 4  (for example). 
     Once the mold is filled with matrix material, the infusion is stopped and the material is allowed to cure due to elevated pressure, temperature, moisture, time, chemical reaction, etc. 
     If desired for an improved, high-quality finish, or for additional environmental protection, an optional gelcoat layer  16  can be applied to one or both exterior surfaces of the panel  10 . 
     In addition to the relatively high-strength patterned structural portions  30  formed by the cured matrix material, the panels may also include special reinforcing elements  12  that are encapsulated/surrounded by the matrix material. As shown in  FIG. 4 , such reinforcing elements  12  may be used where additional strength is required to support heavy structures (a portion of which is shown as item  64 ), or to accommodate additional fasteners, such as screws, bolts, nails, etc.  FIG. 4  illustrates a mounting portion  64  of a mounted component supported by a bolt  60 , nut  62 , and reinforcing element  12 . 
     The panels  10  made as described here have several advantages over other types of panels. For example, once the panels are cured, they require no further assembly and thus comprise fully assembled, solid one piece formed composite panels that are lightweight, strong, resistant to the outside environment, and have good thermal and sound insulating properties. 
     The preceding descriptions and accompanying figures are merely exemplary embodiments of panels  10 . Other structures may be made using the techniques and material described herein, and may not necessarily even be in the form of flat panels. As another example, the internal preforms and resulting patterned structural portions do not have to have the forms and shapes shown (e.g., rectangles, squares, and “stud” shapes), but can instead have complex shapes and different proportions, such as stars, triangles, or other geometric shapes and patterns. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the composite panel, suitable methods and materials are described above. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety to the extent allowed by applicable law and regulations. The composite panel may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive. Any headings utilized within the description are for convenience only and have no legal or limiting effect.