Patent Publication Number: US-2010122763-A1

Title: Composites and Methods of Making the Same

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to an apparatus and method for molding parts. Specifically, it is an apparatus and method for making multi-layer parts. 
     BACKGROUND 
     There is a growing demand by industry, governmental regulatory agencies and consumers for durable and inexpensive products that are functional comparable or superior to metal products. This is particularly true in the automotive and transportation industry. Developers and manufacturers of these products are concerned with the strength parameters, such as impact, bending, stretching, and twisting resilience, while minimizing weight. To meet these demands, a number of reactive thermoplastic and thermoset composite pre-pregs, thermoset and thermoplastic based fully polymerized and consolidated sheets (together called composite sheets), and sandwich materials based on various composite sheets and core materials have been engineered. These materials are usually processed slowly in molds or presses primarily because it takes a long time to heat and cool the mold or press. This long time ends up increasing cost. Therefore there is a need for an improved apparatus and method for making multi-layer parts that is quick to heat yet holds its shape during processing. 
     SUMMARY OF THE INVENTION 
     A first aspect of the present invention provides an apparatus for forming a shape of a composite assembly, comprising: a mold having a first surface and a vacuum bag thereon, wherein the vacuum bag comprises a plurality of vacuum bag sheet(s), and a composite assembly therein, wherein the composite assembly comprises a plurality of bondable layers, wherein at least one of the plurality of sheet(s) of the vacuum bag is between the plurality of bondable layers and the first surface of the mold, and wherein the plurality of bondable layers are able to retain a shape which is the negative image of the mold when the pressure of the inside of the vacuum bag is reduced, even if the bag and plurality of bondable layers of the composite assembly are removed from the mold. 
     A second aspect of the present invention provides a method for forming a shape of a composite assembly, comprising: providing a mold having a first surface and a vacuum bag thereon, wherein the vacuum bag comprises a plurality of vacuum bag sheet(s); providing an apparatus, such as a composite assembly, comprising a plurality of bondable layers, wherein the plurality of bondable layers of the composite assembly are contained within the plurality of sheets of the vacuum bag, wherein at least one of the plurality of sheet(s) of the vacuum bag are between the plurality of bondable layers of the composite assembly and the first surface of the mold; and reducing the pressure inside the plurality of sheet(s) of the vacuum bag so that the plurality of bondable layers are able to retain a shape which is the negative image of the first surface of the mold when the pressure of the inside of the vacuum bag is reduced even when the plurality of bondable layers of the composite assembly are removed from the mold. 
     A third aspect of the present invention provides An apparatus for forming a composite assembly having a composite material support structure (web), comprising: a mold having first and second surfaces; an outer vacuum bag, a plurality of inner vacuum bag(s) and a composite assembly having a composite material support structure (web) therebetween, wherein the composite material support structure (web) runs along an axis orthogonal to a longitudinal axis of the composite assembly, wherein the outer vacuum bag has a shape of a tube, wherein the outer vacuum bag comprises a first sheet conformed against the first surface of the mold and a second sheet conformed against a second surface of the mold, wherein the composite assembly comprises at least one bondable layer(s) L n , wherein n=0, −1, −2 . . . −i, and wherein a first surface of the at least one bondable layer(s) L n=0  of the composite assembly faces and conforms to either a shape of the first surface of the mold and a shape of the first sheet of the outer vacuum bag or to a shape of the second surface of the mold and to a shape of the second sheet of the outer vacuum bag, wherein each successive underlying at least one bondable layer(s) L n , wherein n=−1, −2, . . . −i, conforms to the respective overlying layer L i+n , wherein n=−2, −3, . . . −i, wherein L n , wherein n=−1, −2, . . . −i+1, represents successive underlying at least one bondable layer(s) (L n ) of the composite assembly, wherein n=−i, represents a bottom underlying at least one bondable layer(s) (L n ) of the composite assembly, wherein the first and second sheet(s) of the vacuum bag separate the at least one bondable layer(s) (L n ) of a composite assembly from the first and second surfaces of the mold, wherein the plurality of inner vacuum bag(s) comprise first and second radially expandable sheet(s), disposed about the web&#39;s axis, orthogonal to the longitudinal axis of the composite assembly, conformable to a shape of the at least one L (−i)  layer(s) of the composite assembly, and wherein the at least one bondable layer(s) of the composite assembly being conformed to the shape of the respective shape first sheet of the outer vacuum bag and the first surface of the mold or the shape of the second sheet of the outer vacuum bag and the second surface of the mold are able to retain a shape which is the negative image of the respective first and second surfaces when the vacuum bag is evacuated even if the bag and plurality of bondable layers of the composite assembly are removed from the mold. 
     A fourth aspect of the present invention provides an apparatus for retaining a shape of a hollow composite assembly, comprising: a mold having an internal surface; an outer vacuum bag, at least one inner vacuum bag(s) and the hollow composite assembly, therebetween, wherein the hollow composite assembly comprises i bondable layer(s) L X  between the inner at least one vacuum bag(s) and the outer vacuum bag, wherein the i bondable layer(s) L x  comprise i 1  bondable layer(s) L x  of a first type and i 2  bondable layer(s) L x  of a second type, wherein circumferential portions C x  of the i bondable layer(s) L x  surround a common point within the hollow composite assembly, wherein x=1, 2, 3, . . . (i−1), i; wherein the i bondable layer(s) L X  of the first and second types are denoted as L 1 , L 2 , L 3  . . . , L (i−1) , L i , in order of decreasing distance between a respective point within the circumferential portions of the bondable layer(s) L x  of the first and second types and the common point, wherein i is any positive integer greater than or equal to 1, wherein i=i 1 +i 2 , wherein i 1 ≧0, and i 2 ≧0, wherein i 1 +i 2 ≧1, wherein each i 2  bondable layer(s) L x  of the second type comprises at least one radial portion(s) R x  that are coextensive with each respective circumferential portion C x  of the bondable layer(s) L x  of the second type, wherein the circumferential portions C x  of the i 1  bondable layer(s) L x  of the first type and the circumferential C x  and radial R x  portions of the i 2  bondable layer(s) L x  of the second type have outer and inner surfaces, wherein a distance between points along each outer surface of the circumferential portions C x  of the i bondable layer(s) L X  and the common point is greater than a distance between a respective point along the inner surface of the circumferential portions C x  of the i bondable layer(s) L X  of the first and second types and the common point, wherein a first space separates a wall of the outer vacuum bag from the internal surface of the mold, and wherein a second space separates the hollow composite assembly from the wall of the outer vacuum bag and a wall of the at least one inner vacuum bag(s), wherein, when the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (i−1) , L i  of the hollow composite assembly are conformed to the internal surface of the mold, a shape of the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (i−1) , L i  of the first and second types of the hollow composite assembly is the negative image of the internal surface of the mold, when the first space between the internal surface of the mold and the wall of the outer vacuum bag and the second space separating the composite assembly from the wall of the outer vacuum bag and a wall of the at least one inner vacuum bag(s) are under vacuum, wherein the at least one radial portion(s) R x  that are coextensive with each respective circumferential portion C x  of the bondable layer(s) L x  of the second type establish or fix a distance between points within each circumferential portion C x  of the i bondable layer(s) L X  of the first and second types and the common point so that a distance between respective points and the common point is essentially the same when the hollow composite assembly and the outer and inner vacuum bags are within the mold as when they are removed from the mold. 
     A fifth aspect of the present invention provides an apparatus for retaining a shape of a hollow composite assembly, comprising: an outer vacuum bag, at least one inner vacuum bag(s) and the hollow composite assembly, therebetween, wherein the hollow composite assembly comprises i bondable layer(s) L X  between the inner at least one vacuum bag(s) and the outer vacuum bag, wherein the i bondable layer(s) L X  comprise i 1  bondable layer(s) L X  of a first type and i 2  bondable layer(s) L X  of a second type, wherein circumferential portions C X  of the i bondable layer(s) L X  surround a common point within the hollow composite assembly, wherein x=1, 2, 3, . . . (i−1), i; wherein the i bondable layer(s) L X  of the first and second types are denoted as L 1 , L 2 , L 3  . . . , L (i−1) , L i , in order of decreasing distance between a respective point within the circumferential portions of the bondable layer(s) L X  of the first and second types and the common point, wherein I is any positive integer greater than or equal to 1, wherein i=i 1 +i 2 , wherein i 1 ≧0, and i 2 ≧0, wherein i 1 +i 2 ≧1, wherein each i bondable layer(s) L X  of the second type comprises at least one radial portion(s) R x  that are coextensive with each respective circumferential portion of the bondable layer(s) L X  of the second type, wherein the circumferential portions of the i 1  bondable layer(s) L X  of the first type and the circumferential and radial portions of the i 2  bondable layer(s) L X  of the second type have outer and inner surfaces, wherein a distance between points along each outer surface of the i bondable layer(s) L X  and the common point is greater than a distance between a respective point along the inner surface and the common point, wherein a first space separates a wall of the outer vacuum bag from the internal surface of the mold, and wherein a second space separates the composite assembly from the wall of the outer vacuum bag and a wall of the at least one inner vacuum bag(s), wherein, when the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (i−1) , L i  of the hollow composite assembly are conformed to an internal surface of a mold, a shape of the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly is the negative image of the internal surface of the mold, when the first space between the internal surface of the mold and the wall of the outer vacuum bag and the second space separating the composite assembly from the wall of the outer vacuum bag and a wall of the at least one inner vacuum bag(s) are under vacuum, wherein the at least one radial portion(s) R X  that are coextensive with each respective circumferential portion of the bondable layer(s) L X  of the second type establish or fix a distance between points within each circumferential portion of the i bondable layer(s) L X  and the common point so that a distance between respective points and the common point is essentially the same when the hollow composite assembly and the outer and inner vacuum bags are within the mold as when they are removed from the mold. 
     A sixth aspect of the present invention provides a method of making a hollow composite assembly, comprising: providing a mold having an inner surface; providing an outer vacuum bag, at least one inner vacuum bag(s) and the hollow composite assembly, therebetween, wherein the hollow composite assembly comprises i bondable layer(s) L X  between the inner at least one vacuum bag(s) and the outer vacuum bag, wherein the i bondable layer(s) L X  comprise i 1  bondable layer(s) L X  of a first type and i 2  bondable layer(s) L X  of a second type, wherein circumferential portions C X  of the i bondable layer(s) L X  surround a common point within the hollow composite assembly, wherein x=1, 2, 3, . . . (i−1), i; wherein the i bondable layer(s) L X  of the first and second types are denoted as L 1 , L 2 , L 3  . . . , L (i−1) , L i , in order of decreasing distance between a respective point within the circumferential portions of the bondable layer(s) L X  of the first and second types and the common point, wherein i is any positive integer greater than or equal to 1, wherein i=i 1 +i 2 , wherein i 1 ≧0, and i 2 ≧0, wherein i 1 +i 2 ≧1, wherein each bondable layer(s) L X  of the second type comprises at least one radial portion(s) R X  that are coextensive with each respective circumferential portion of the bondable layer(s) L X  of the second type, wherein the circumferential portions of the i 1  bondable layer(s) L X  of the first type and the circumferential and radial portions of the i 2  bondable layer(s) L X  of the second type have outer and inner surfaces, wherein a distance between points along each outer surface of the i bondable layer(s) L X  and the common point is greater than a distance between a respective point along the inner surface and the common point, wherein a first space separates a wall of the outer vacuum bag from the internal surface of the mold, and wherein a second space separates the composite assembly from the wall of the outer vacuum bag and a wall of the at least one inner vacuum bag(s), providing a vacuum to a first and second spaces, wherein, the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly are conformed to an internal surface of the mold, a shape of the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly is the negative image of the internal surface of the mold, when the first space between the internal surface of the mold and the wall of the outer vacuum bag and the second space separating the composite assembly from the wall of the outer vacuum bag and a wall of the at least one inner vacuum bag(s) are under vacuum, removing the hollow composite assembly from the mold, wherein, the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly retain the shape of the wall of the outer vacuum bag and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly that is the negative image of the internal surface of the mold, and wherein the at least one radial portion(s) R X  that are coextensive with each respective circumferential portion of the bondable layer(s) L X  of the second type establish or fix a distance between points within each circumferential portion of the i bondable layer(s) L X  and the common point so that a distance between respective points and the common point is essentially the same when the hollow composite assembly and the outer and inner vacuum bags are within the mold as when they are removed from the mold. 
     In one embodiment, the method of making a hollow composite assembly, further comprises removing the composite assembly and the vacuum bag from the mold and heating the composite assembly inside the vacuum bag between about 80° C. and 260° C. 
     A seventh aspect of the present invention provides A method for fixing the solid geometric shape of a hollow composite assembly, comprising: withdrawing air from a first space, in antiparallel directions, resulting in conforming a wall of an inner vacuum bag to a surface of a mold; withdrawing air from a second space, in antiparallel directions, resulting in conforming a wall of an outer vacuum bag to a wall of the hollow composite assembly; said conforming the wall of the outer vacuum bag to the wall of the hollow composite fixing the geometric shape of the hollow composite assembly, resulting in the hollow composite assembly having a shape in the negative image of the surface of the mold 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the invention are set forth in the appended claims. The invention itself, however, will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  depicts a cross-sectional view of an assembly, having a plurality of layers, before bending; 
         FIG. 2  depicts a cross-sectional view of the assembly depicted in  FIG. 1 , after bending, without clamping or bonding adjacent layers; 
         FIG. 3  depicts a cross-sectional view of the assembly depicted in  FIG. 1 , wherein adjacent layers are first bonded (or clamped), then bent in order to contrast bending with and without clamping; 
         FIG. 4  depicts a cross-sectional view of an apparatus for making a multi-layer apparatus, according to embodiments of the present invention; 
         FIG. 5  depicts the cross-sectional view of the apparatus depicted in  FIG. 4 , after evacuating a vacuum bag, according to embodiments of the present invention; 
         FIG. 6  depicts the cross-sectional view of the apparatus depicted in  FIG. 5 , after removing a mold, according to embodiments of the present invention; 
         FIGS. 7A-B  depict a flow diagram of a method for free-forming a shape of a composite assembly, according to embodiments of the present invention; 
         FIGS. 8A-8B  depicts a longitudinal cross-sectional view of an apparatus for retaining a shape of a hollow composite assembly, according to embodiments of the present invention; 
         FIG. 8C  depicts a flow diagram for a method for retaining a shape of a composite assembly, according to embodiments of the present invention; 
         FIG. 9  depicts an end cross-sectional view of the apparatus for retaining the shape of the hollow composite assembly, according to embodiments of the present invention; 
         FIG. 10  depicts an exploded view of the end-cross-sectional view of the apparatus for retaining the shape of the hollow composite assembly, depicted in  FIG. 9 , according to embodiments of the present invention; 
         FIG. 11  depicts the end cross-sectional view of the apparatus for retaining the shape of the hollow composite assembly, depicted in  FIG. 8 , according to embodiments of the present invention; and 
         FIGS. 12A-12B  depict a flow diagram describing a method for making a hollow composite assembly, according to embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The invention meets a need in the art by providing multi-layered parts, and methods of forming therewith. 
       FIGS. 1-3  illustrate the effect of clamping or bonding multi-layered composite assemblies. Bending stiffness of a sheet of a particular homogeneous material (aluminum, steel for example) will increase with the cube of its thickness. So, if the thickness doubles, the bending stiffness goes up by 8, if the thickness triples the bending stiffness goes up by 27, and so on. It is also well known that multiple layers of sheets will have much lower bending stiffness if they are not bonded or clamped so they act as one, compared to the bonded or clamped case. This difference has to do with the difference between the cube of the sum of the thicknesses (Σi) 3 , which is the bonded case, and the sum of the cubes of the individual thicknesses Σ(i 3 ), which is the unbonded case. 
       FIG. 1  depicts a cross-sectional view of an assembly  5 , having a plurality of layers  7 , in which adjacent layers are free to slide relative to one another. A nominal thickness of 1 (for example) may be assigned to each layer  7  of assembly  5  in  FIG. 1 . 
       FIG. 2  depicts the cross-sectional view of the assembly  5 , having a plurality of layers  7 , depicted in  FIG. 1 , after bending, without clamping adjacent layers  7 . Each of four (4) layers  7  shown in  FIG. 2  may slide relative to each adjacent layer, as can be seen by the overlapping of respective ends  14  of each successive adjacent layer  7 . Therefore, the assembly  5  may be assigned a contribution from thickness to bending stiffness of 4, since each layer  7  bends individually, with a thickness contribution to bending stiffness of 1 3  for each of the four (4) layers  7 , 4 total. 
       FIG. 3  depicts the cross-sectional view of the assembly  5 , having a plurality of layers  7 , depicted in  FIG. 1 , after bending, with clamping of adjacent layers  7  applied before bending. The adjacent layers  7  may be bent, although they are clamped together. In  FIG. 3 , the four (4) adjacent layers  7  interact and tend to bend as an integral unit. Therefore, the assembly  5  may be assigned a contribution from thickness to bending stiffness of 4 3 =64, which is 16 times greater than the bending stiffness of the unclamped assembly  5  based on 4 3  for the four (4) layers  7 , 64 total. This shows the effect of clamping or bonding the layers together on bending stiffness of the assembly  5 . 
     The clamping effect may be achieved by a creating a vacuum around the assembly  5 , such as by placing the assembly  5  in a vacuum bag. An objective of the invention is to bend the composite assembly before the vacuum is applied, so the layers slide and the assembly bends easily, then once the desired shape is achieved, another objective of the invention is to use vacuum to apply and provide the clamping of adjacent layers  7  and the stiffening effect, so the assembly can be removed from a mold. The vacuum bag stiffening effect is then maintained through the process of bonding of the layers by some means. The part can then be removed from the vacuum bag and retain its shape. The clamping effect may also be achieved by placing a vacuum bag around a sandwich panel with a core and a skin on each side by applying vacuum to the sandwich panel. 
       FIG. 4  depicts a cross-sectional view of an apparatus  50  for making apparatus  10 , such as a multi-layered composite part  10 , having a plurality of bondable layer(s)  12 . The apparatus  50  comprises: an apparatus  71 , and a mold  51 , having a first surface  46 . The apparatus  71  comprises a vacuum bag  45 , and an apparatus  10 , such as reactive thermoplastic or thermoset composite pre-pregs, thermoset and thermoplastic based fully polymerized and consolidated sheets (together called composite sheets), and sandwich materials based on various composite sheets and core materials, in the vacuum bag  45 . The vacuum bag  45  comprises a plurality of vacuum bag sheets  53 ,  55 . 
     In one embodiment, the apparatus  50  for forming a shape of the apparatus  10 , such as a composite assembly, comprises: a mold  51  having a first surface  46  and a vacuum bag  45  thereon, wherein the vacuum bag  45  comprises a plurality of vacuum bag sheet(s)  53 ,  55 , and the apparatus  10  therein. 
     The apparatus  10  comprises a plurality of bondable layers  12 . Hereinafter, “bondable layer(s)” is defined as layers that are to be chemically or physically coupled by a bonding agent, such as by an adhesive. Typical adhesives may be a thermoplastic or thermoset resin. One of the plurality of sheet(s)  55  of the vacuum bag  45  are between the plurality of bondable layers  12  and the first surface of the mold  46 . Vacuum may be applied between the first surface  46  of the mold  51  and the bottom surface  49  of the apparatus  71 , thereby conforming a shape of the bottom surface  49  of the apparatus  71  to the reverse image of the first surface  46  of the mold  51 . The bottom surface  49  of the apparatus  71  may be prepared for applying vacuum by taping it to the first surface  46  of the mold  51 , thereby sealing the bottom surface  49  of the apparatus  71  to the first surface  46  of the mold  51 . 
     Applying vacuum in the direction of arrow  77  between the bottom surface  49  of the apparatus  71  and the first mold surface  46  draws the apparatus  71  toward the first mold surface  46  in the direction of the arrow  77  and conforms the shape of the surface  49  of apparatus  71  to the mold surface  46 . Alternatively, the force in the direction of arrow  77  could be physical pressure, or other means, to hold the surface  49  of the apparatus  71  against the first surface  46  of the mold  51 . 
       FIG. 5  depicts the cross-sectional view of the apparatus  50  depicted in  FIG. 4 , after evacuating a vacuum bag  45  by removing air from the vacuum bag  45 . Vacuum is applied in the direction of the arrows  57 ,  58  between the top and bottom vacuum bag sheets  53 ,  55 , clamping the apparatus  10 , such as a composite assembly inside, and forming it to the reverse image of the first surface  46  of the mold  51 . 
       FIG. 6  depicts the cross-sectional view of the apparatus  71  depicted in  FIG. 5 , after removing the mold  51  in the direction of the arrow  73 . Vacuum is released between the bottom vacuum bag sheet  55  and the first surface  46  of the mold  51 , thus freeing the apparatus  71  comprising the vacuum bag  45  and apparatus  10 , such as a composite assembly, from the mold  51 . The vacuum bag  45  and apparatus  10  is apparatus  71 , such as a free standing assembly depicted in  FIG. 6 , and described in associated text, herein, which can now undergo further processing, such as a heating cycle, or simply time for a room temperature cure adhesive to bond the layers and allow removal of the part from the vacuum bag  45 , while the first surface  46  of the mold  51  is available to form another apparatus  10 . 
     The plurality of bondable layers  12  are able to retain a shape which is the negative image of the mold  51  when the pressure of the inside of the vacuum bag  45  is reduced, even if the bag  45  and plurality of bondable layers  12  of the apparatus  10 , such as a composite assembly are removed from the mold  51 . 
     The materials of the apparatus  10  may be formed into the desired shape while the vacuum is off, according to the shape of the first surface  46  of the mold  51 , through the vacuum bag  45 . The vacuum is then applied, locking the plurality of adjacent layers  12  of the apparatus  71 . The apparatus  71  can then be heat processed in the mold  51  or in a second similarly shaped mold (not shown) that may be made of a different material than the first mold, or in an oven (not shown) by removing the apparatus  71  from the mold  51 , or otherwise heat processed in a heating device between about 80° C. and about 260° C., without being attached to a shaping fixture, e.g., the mold  51 . The mold  51  could be as simple as a flat plate, facilitating the manufacture of flat panels, or it could be as complex as a wind turbine blade. 
     In one embodiment, the mold  51  may be a cold forming mold, so the apparatus  10  may be released from the cold forming mold, and transferred to a hot mold for heat processing. Applying vacuum in the direction of arrow  77  between the bottom surface  49  of the apparatus  71  and the first mold surface  46  draws the apparatus  71  toward the first mold surface  46  in the direction of the arrow  77  and conforms the shape of the surface  49  of apparatus  71  to the mold surface  46 . Providing intimate contact between the first mold surface  46  and the surface  49  of the apparatus  71  enables rapid heating and heat processing of the apparatus  10 . The apparatus  10  may be demolded after heat processing, or it may be transferred to another cold mold for cooling. 
     In one embodiment, the plurality of bondable layers of the apparatus  10 , such as a composite assembly, are reactive polymer pre-impregnated reinforcement materials (pre-pregs). 
     In one embodiment, the plurality of bondable layers of the apparatus  10 , such as a composite assembly, are layers of preformed sheets of various materials and thicknesses according to the intended use. 
     In one embodiment, the plurality of bondable layers of the apparatus  10 , such as a composite assembly, are preformed sheets on each side of a foam core, or other suitable core material. 
     In one embodiment, the plurality of bondable layers of the apparatus  10 , such as a composite assembly, are combinations of reactive polymer pre-impregnated reinforcement materials (pre-pregs), layers of preformed sheets of various materials and thicknesses according to the intended use, or preformed sheets on each side of a foam core, or other suitable core material. 
     In one embodiment, the plurality of bondable layers of the apparatus  10 , such as a composite assembly, are coupled by a bonding material. The bonding material may be a thermoset or a thermoplastic film adhesive, such as ethyl vinyl acetate (EVA). 
     Alternatively, the thermoplastic film is advantageously selected from the group consisting of the reactive (polymerizable) thermoplastic resin may be reactive macrocyclic oligomeric polyester, reactive macrocyclic oligomeric polybutyleneterephthalate, reactive macrocyclic oligomeric polyethyleneterephthalate, reactive macrocyclic oligomeric polycarbonate, and reactive lactam monomers. 
     The thermoset film is advantageously selected from the group consisting of epoxy resins, unsaturated polyester resins, vinyl ester resins, thermoset polyurethane resins, phenol-formaldehyde resins (phenolic resins), polyimide resins, silicone resins, crosslinked thermoplastic resins, e.g., cross linked polyethylene resins, cross linked polypropylene resins, and cross linked polyvinyl chloride resins. A comprehensive listing of thermoset resins may be found in “Handbook of Thermoset Resins,” 2 nd  Edition, by Sidney H. Goodman, Noyes Publications, Westwood, N.J., ISBN: 0-8155-1421-2 (1998), which is hereby incorporated by reference. 
     In one embodiment, the apparatus  10 , such as a composite assembly, comprises “non-bonding” layers to separate smooth finished surfaces of the composite assembly. The “non-bonded” layers may be thin sheets of material, wherein the material is selected from the group consisting of metal, and plastic, with a mold release agent between the non-bonding layer and the composite. The mold release agent may be a silicone release agent. The “non-bonding” layers may be thin sheets of material, wherein the material is selected from the group consisting of metal and plastic. The metal may advantageously be selected from the group consisting of steel, aluminum, copper, silver, and tin. The plastic may advantageously be plastic selected from the group consisting of polyethyleneterephthalate (PET), silicone, fluorinated ethylene propylene, polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer resin, PFA, polyfluoroalkanes, polyethylene film, and polypropylene film. 
     In one embodiment, a shape of the first surface  46  of the mold  51  is selected from the group consisting of flat, concave, convex, and combinations thereof. 
       FIGS. 7A-7B  depict a flow diagram of a method  100  for forming a shape of the apparatus  10 , such as a composite assembly. The method  100  comprises a step  105 , providing a mold  51  having a first surface  46  and a vacuum bag  45  thereon, wherein the vacuum bag  45  comprises a plurality of vacuum bag sheet(s)  53 ,  55 . 
     In a step  110  of the method  200 , an apparatus  10 , such as a composite assembly, is provided, comprising a plurality of bondable layers  12 , wherein the plurality of bondable layers  12  of the apparatus  10 , such as the composite assembly, are contained within the plurality of sheets  53 ,  55  of the vacuum bag  45 . At least one of the plurality of sheet(s)  53 ,  55  of the vacuum bag  45  are between the plurality of bondable layers  12  of the apparatus  10 , such as the composite assembly, and the first surface  46  of the mold  51 . 
     In a step  115  of the method  200 , the pressure inside the plurality of sheet(s)  53 ,  55  of the vacuum bag  45  is reduced so that the plurality of bondable layers  12  are able to retain a shape which is the negative image of the first surface  46  of the mold  51  when the pressure of the inside of the vacuum bag  45  is reduced even when the plurality of bondable layers  12  of the apparatus  10 , such as a composite assembly, are removed from the mold  51 . 
       FIG. 8A  depicts a longitudinal cross-sectional view of an apparatus  200  for retaining a shape of a hollow composite assembly  205 , comprising: a mold  220 , having an internal surface  213 , an outer vacuum bag  201 , “j” inner vacuum bag(s)  203 ,  204 , wherein j is at least one, and the hollow composite assembly  205 , therebetween. The mold  220  may comprise two halves  109 ,  111 . A first space  107  may separate a wall  202  of the outer vacuum bag  201  from the internal surface  213  of the mold  220 . A second space  115  separates the hollow composite assembly  205  from the wall  202  of the outer vacuum bag  201  and a wall  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204 . 
       FIG. 8B  depicts a longitudinal cross-sectional view of an apparatus  600  for retaining a shape of a hollow composite assembly  605 , comprising: a mold  620 , having an outer surface  613 , an outer vacuum bag  601 , an inner vacuum bag  603 , and the hollow composite assembly  605 , therebetween. The mold  620  may be any solid shape, e.g., cylindrical, rhomboid, pyramidal, or the like. A first space  657  may separate a wall  630  of the inner vacuum bag  603  from the outer surface  613  of the mold  620 . A second space  615  separates wall  604  of the hollow composite assembly  605  from the wall  608  of the inner vacuum bag and the wall  625  of the hollow composite assembly  605  from the wall  602  of the outer vacuum bag  601 . 
       FIG. 8B  depicts a longitudinal cross-sectional view of the apparatus  600  for retaining a shape of a hollow composite assembly  605 , wherein the mold  620  is an internal mold. 
       FIG. 8C  depicts a method  700  for advantageously fixing the solid geometric shape of the hollow composite assembly  605 , depicted in  FIG. 8B . 
     In a step  705  of the method  700 , air may be withdrawn from the first space  657 , in the antiparallel directions represented by the arrows  607 ,  609 , resulting in conforming the wall  630  of the inner vacuum bag  603  to the surface  613  of the mold  620 . 
     In a step  710  of the method  700 , air may be withdrawn from the second space  615 , in the antiparallel directions represented by the arrows  607 ,  609 , resulting in conforming the wall  602  of the outer vacuum bag  601  to the wall  625  of the hollow composite assembly  605 . Said conforming the wall  625  of the outer vacuum bag  601  to the wall  625  of the hollow composite assembly  605  fixes the geometric shape of the hollow composite assembly  605 , resulting in the hollow composite assembly  605  having a shape in the negative image of the surface  613  of the mold  620 . 
     In a step  715  of the method  700 , the pressure in first space  657  may be allowed to return to atmospheric pressure, resulting in releasing the mold  620  so it can be removed, thereby forming the cavity  621  within the hollow composite assembly  605 . 
     In one embodiment of the step  710  of the method  700 , the air may be withdrawn from the spaces  657 ,  615  by withdrawing air via pumping, e.g., using a mechanical vacuum pump, or any appropriate means of evacuating the spaces  657 ,  615 , in the direction of arrows  607  and  609 . 
     In one embodiment of the step  710  of the method  700 , the pressure in first space  657  may be allowed to return to atmospheric pressure, resulting in releasing the mold  620  so it can be removed, thereby forming a cavity  621  within the hollow composite assembly  605 . 
     In one embodiment of the step  710  of the method  700 , air is withdrawn from the first and second spaces  657 ,  615  by withdrawing the air via pumping. 
     In one embodiment of the step  710  of the method  700 , the air is withdrawn by a mechanical vacuum pump, in the antiparallel directions represented by the arrows  607 ,  609 , e.g., using the mechanical vacuum pump. 
       FIG. 9  depicts an end cross-sectional view of the apparatus  200  for retaining the shape of the hollow composite assembly  205 . The hollow composite assembly  205  comprises i bondable layer(s) L X  between the inner at least one vacuum bag(s)  203 ,  204  and the outer vacuum bag  201 , wherein X=1, 2, 3, . . . (i−1), i. The i bondable layer(s) L X  comprise i 1  bondable layer(s) L X  of a first type and i 2  bondable layer(s) L X  of a second type. The i 1  bondable layers(s) L X  of the first type have only C X  circumferential portion(s)  133 . The i 2  bondable layers of the second type have C X  circumferential portion(s)  133  and R x  radial portion(s)  127 . C X  circumferential portion(s)  133  of the i bondable layer(s) L X  surround a common reference point  160  within the hollow composite assembly  205 , wherein X=1, 2, 3, . . . (i−1), i. i may be any positive integer greater than or equal to 1. 
     The number I of bondable layer(s) may be represented by formula: 1, as follows: 
         i=i   1   +i   2 , wherein  i   1 ≧0, and  i   2 ≧0, and wherein  i   1   +i   2 ≧1.  (1) 
     The i bondable layer(s) L X  of the first and second types are denoted as L 1 , L 2 , L 3  . . . , L (I−1) , L I , in order of decreasing distance between a respective reference point  163 ,  166 ,  167 ,  169 , and  171  within the C X  circumferential portion(s)  133  of the bondable layer(s) L X  of the first and second types and the common reference point  160 . Each of the reference points  163 ,  166 ,  167 ,  169 , and  171  lie along a plane that includes the common reference point  160 , and are separated from the common reference point  160  by a distance “d”. 
     Each of the i 2  bondable layer(s) L X  of the second type comprises at least one R X  radial portion(s)  127  that are coextensive with each respective C X  circumferential portion(s)  133  of the i 2  bondable layer(s) L X  of the second type. 
       FIG. 10  depicts an exploded view of the end-cross-sectional view of the apparatus  200  for retaining the shape of the hollow composite assembly  205 , depicted in  FIG. 9 , and described in associated text, herein. C X  circumferential portions  133  of the i 1  bondable layer(s) L X  of the first type, wherein X=1, 2, and 3, have inner surface(s)  236 ,  238 , and  240 , and outer surface(s)  246 ,  248 , and  250 . C X  circumferential portion(s)  133  of the i bondable layer(s) L X  of the second type, wherein X=(i−1) and i, have inner surface(s)  242  and  244 , and outer surfaces  252  and  254 . 
     R x  radial portion(s)  127  of the i 2  bondable layer(s) L X  of the second type, wherein X=(i−1) and I, have inner surface(s)  262 , and  260 , and  270 , and outer surfaces  256 ,  258 . 
     In  FIG. 9 , each j inner vacuum bag(s)  203 ,  204  forms a cavity  128 ,  129 , and each cavity has a reference point  173 ,  175 , wherein the reference points lie along a plane that includes the common reference point  160 , and are separated from the common reference point  160  by a distance “d”. 
     A distance between reference points  163 ,  166 ,  167 ,  169 , and  171  along each outer surface of the C x  circumferential portion(s)  133  of the i bondable layer(s) L X  of the first and second type and the common reference point  160  is greater than a distance between a respective point along the inner surface(s)  236 ,  238 ,  240 ,  242 , and  244  of the C x  circumferential portion(s)  133  of the i bondable layer(s) L X  and the common reference point  160 . 
     Referring to  FIG. 8 , a first space  107  separates a wall  202  of the outer vacuum bag  201  from the internal surface  213  of the mold  220 . A second space  115  separates the hollow composite assembly  205  from the wall  202  of the outer vacuum bag  201  and a wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204 . 
     When a  137 , which includes the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  are conformed to the internal surface  213  of the mold  220 , a shape of the wall  202  of the outer vacuum bag  201  and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205  is the negative image of the internal surface  213  of the mold  220 , when the first space  107  between the internal surface  213  of the mold  220  and the wall  202  of the outer vacuum bag  201  and the second space  115  separating the composite assembly  205  from the wall  202  of the outer vacuum bag  201  and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  have a lower internal pressure than the internal pressure of the j at least one inner vacuum bags  203 ,  204 . 
     In one embodiment,  FIG. 8  depicts the first space  107  between the internal surface  213  of the mold  220  and the wall  202  of the outer vacuum bag  201  and the second space  115  separating the composite assembly  205  from the wall  202  of the outer vacuum bag may be placed at a lower internal pressure than the internal pressure of the j at least one inner vacuum bag(s)  203 ,  204  by withdrawing air via pumping, e.g., using a mechanical vacuum pump, or any appropriate means of evacuating the spaces  107  and  115 , in the direction of arrows  207  and  209 , while leaving the j at least one inner vacuum bag(s)  203 ,  204  open to a higher source of air pressure, such as atmospheric pressure. 
     The at least one R X  radial portion(s)  127  of the i 2  bondable layer(s) L X  of the second type that are coextensive with each respective C x  circumferential portion)s)  133  of the bondable layer(s) L X  of the second type establish or fix a distance between reference points  163 ,  166 ,  167 ,  169 , and  171  within each C x  circumferential portion(s)  133  of the i bondable layer(s) L X  of the first and second types and the common reference point  160  so that a distance between respective reference points  163 ,  166 ,  167 ,  169 , and  171  and the common reference point  160  is essentially the same when the hollow composite assembly  205  and the outer  201  and inner vacuum bags  203  are within the mold  220  as when they are removed from the mold  220 . 
       FIG. 11  depicts the end cross-sectional view of the apparatus  200  for 
     retaining the shape of the hollow composite assembly  205 , depicted in  FIG. 8 , and described in associated text, comprising j inner vacuum bag(s)  203 ,  204 , wherein j is equal to 4. Each j inner vacuum bag(s)  203 ,  204  forms a cavity  162 ,  164 ,  166 , and  168 , and each cavity has a reference point  170 ,  172 ,  174 , and  176 , wherein the reference points lie along a plane that includes the common reference point  160 , and are separated from the common reference point  160  by a distance “d”. 
     In one embodiment, the j at least one inner vacuum bag(s)  203 ,  204  are advantageously expandable when the outer vacuum bag  201  is evacuated. 
     In one embodiment, the bondable layer(s) (L X ) of the hollow composite assembly  205  are reactive polymer pre-impregnated reinforcement materials (pre-pregs). 
     In one embodiment, the bondable layer(s) (L X ) of the hollow composite assembly  205  are layers of preformed sheets of various materials and thicknesses according to the intended use. 
     In one embodiment, the bondable layer(s) (L X ) of the hollow composite assembly  205  are preformed sheets on each side of a foam core, or other suitable core material. 
     In one embodiment, the bondable layer(s) (L X ) of the hollow composite assembly  205  are combinations of reactive polymer pre-impregnated reinforcement materials (pre-pregs), layers of preformed sheets of various materials and thicknesses according to the intended use, or preformed sheets on each side of a foam core, or other suitable core material. 
     In one embodiment, the bondable layer(s) (L X ) are coupled by a bonding material. 
     In one embodiment, the bonding material coupling the bondable layers L x  is a thermoplastic or a thermoset film adhesive. 
     In one embodiment, the thermoplastic film adhesive coupling the bondable layers L x  is selected from the group consisting of ethyl vinyl acetate (EVA) film adhesive, co-polyaminde film adhesive, co-polyester film adhesive, polypropylene film adhesive, polyethylene film adhesive, polyurethane film adhesive, multi-layered film adhesive, and combinations thereof. 
     In one embodiment, the thermoplastic film adhesive coupling the bondable layers L x  is selected from the group consisting of the reactive (polymerizable) thermoplastic resin may be reactive macrocyclic oligomeric polyester, reactive macrocyclic oligomeric polybutyleneterephthalate, reactive macrocyclic oligomeric polyethyleneterephthalate, reactive macrocyclic oligomeric polycarbonate, and reactive lactam monomers. 
     In one embodiment, the thermoplastic film adhesive coupling the bondable layers L x  is selected from the group consisting of epoxy resins, unsaturated polyester resins, vinyl ester resins, thermoset polyurethane resins, phenol-formaldehyde resins (phenolic resins), polyimide resins, silicone resins, crosslinked thermoplastic resins, e.g., cross linked polyethylene resins, cross linked polypropylene resins, and cross linked polyvinyl chloride resins. 
     In one embodiment, the hollow composite assembly  205  comprises “non-bonding” layers to separate smooth finished surfaces of the hollow composite assembly  205 . 
     In one embodiment, the “non-bonded” layers are thin sheets of material, wherein the material is selected from the group consisting of steel, aluminum, and plastic. 
     In one embodiment, the plastic is advantageously selected from the group consisting of polyethyleneterephthalate (PET), silicone, fluorinated ethylene propylene, polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer resin, PFA, polyfluoroalkanes, polyethylene film, and polypropylene film. 
     In one embodiment, a shape of the first surface  213  of the mold  220  is selected from the group consisting of flat, concave, convex, and combinations thereof. 
       FIGS. 12A-12B  depict a flow diagram describing a method  300  for making a hollow composite assembly  205 . The method  300  comprises a step  305  in which a mold  220 , having an inner surface  213 , is provided. 
     In a step  310  of the method  300  a vacuum bag assembly  133  comprising: an outer vacuum bag  201 , j at least one inner vacuum bag(s)  203 ,  204  and the hollow composite assembly  205 , therebetween, is provided. 
     The hollow composite assembly  205  comprises i bondable layer(s) L X  between the inner at least one vacuum bag(s)  203 ,  204  and the outer vacuum bag  201 . The i bondable layer(s) L x  comprise i 1  bondable layer(s) L x  of a first type and i 2  bondable layer(s) L x  of a second type, wherein C x  circumferential portion(s)  133  of the i bondable layer(s) L x  surround a common reference point  160  within the hollow composite assembly  205 , wherein x=1, 2, 3, . . . (i−1), i. I may be any positive integer greater than or equal to 1. 
     The number i of bondable layer(s) may be represented by formula 1, as follows: 
         i=i   1   +i   2 , wherein  i   1 ≧0, and  i   2 ≧0, and wherein  i   1   +i   2 ≧1.  (1) 
     The i bondable layer(s) L X  of the first and second types are denoted as L 1 , L 2 , L 3  . . . , L (i−1) , L i , in order of decreasing distance between a respective reference point  163 ,  166 ,  167 ,  169 , and  171  within the C X  circumferential portion(s)  133  of the bondable layer(s) L x  of the first and second types and the common reference point  160 . Each of the i 2  bondable layer(s) L X  of the second type comprises at least one R x  radial portion(s)  127  that are coextensive with each respective C x  circumferential portion(s)  133  of the i 2  bondable layer(s) L x  of the second type. 
     C x  Circumferential portion(s)  133  of the i 1  bondable layer(s) L x  of the first type, wherein x=1, 2, and 3, have inner surface(s)  236 ,  238 , and  240 , and outer surface(s)  246 ,  248 , and  250 . C x  circumferential portion(s)  133  of the i bondable layer(s) L x  of the second type, wherein x=(i−1) and i, have inner surface(s)  242  and  244 , and outer surfaces  252  and  254 . 
     R x  radial portion(s)  127  of the i 2  bondable layer(s) L x  of the second type, wherein x=(i−1) and I, have inner surface(s)  262 , and  260 , and  270 , and outer surfaces  256 ,  258 . 
     A distance between reference points  163 ,  166 ,  167 ,  169 , and  171  along each outer surface of the C x  circumferential portion(s)  133  of the i bondable layer(s) L X  of the first and second type and the common reference point  160  is greater than a distance between a respective point along the inner surface(s)  236 ,  238 ,  240 ,  242 , and  244  of the C x  circumferential portion(s)  133  of the i bondable layer(s) L x  and the common reference point  160 . 
     In the step  315  of the method  300 , a vacuum is provided to the first  107  and second  115  spaces. The vacuum assembly  137 , which includes the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (i−1) , L i  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  is conformed to an internal surface  213  of the mold  220 , so that a shape of the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (i−1) , L i  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the inner vacuum bag(s)  203 ,  204  is the negative image of the internal surface  213  of the mold  220 , when the first space  107  between the internal surface  213  of the mold  220  and the wall  202  of the outer vacuum bag  201  and the second space  115  separating the composite assembly  205  from the wall  202  of the outer vacuum bag are under vacuum. 
     In a step  320  of the method  300 , the hollow composite assembly  205  is removed from the mold  220 . The vacuum assembly  137  that includes the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  are conformed to an internal surface  213  of the mold  220 , so that a shape of the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  is the negative image of the internal surface  213  of the mold  220 , when the first space  107  between the internal surface  213  of the mold  220  and the wall  202  of the outer vacuum bag  201  and the second space  115  separating the composite assembly  205  from the wall  202  of the outer vacuum bag  201  are under vacuum. 
     The vacuum assembly  137  that includes the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  retains a shape of the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the hollow composite assembly, and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204 , that is the negative image of the internal surface  213  of the mold  220 , and the at least one R X  radial portion(s)  127  that are coextensive with each respective C x  circumferential portion(s)  133  of the bondable layer(s) L X  of the second type establish or fix a distance “d” between reference points  163 ,  166 ,  167 ,  169 , and  171  within each C x  circumferential portion(s)  133  of the i bondable layer(s) L X  of the first and second types and the common reference point  160 , so that a distance between respective reference points  163 ,  166 ,  167 ,  169 , and  171  and the common reference point  160  is essentially the vacuum assembly  137  is within the mold  220 , as when the vacuum assembly  137  is removed from the mold  220 . 
     In one embodiment of the step  310  of the method  300 , at least two inner vacuum bag(s)  203 ,  204  are provided, i.e., j is greater than or equal to two. 
     In one embodiment of the step  315  of the method  300 , the hollow composite assembly  205  and j at least one inner vacuum bag(s)  203 ,  204  are heated to a temperature greater than or equal to 25° C. inside the outer vacuum bag  201 , after applying a vacuum to the first  107  and second spaces  115 . 
     In one embodiment of the step  315  of the method  300 , the hollow composite assembly  205  and at least one inner vacuum bag(s)  203 ,  204  are heated between about 50° C. and about 250° C. inside the outer vacuum bag  201  after applying a vacuum to the first  107  and second spaces  115 . 
     In one embodiment of the step  315  of the method  300 , the hollow composite assembly  205  and at least one inner vacuum bag(s)  203 ,  204  are heated between about 100° C. and about 250° C. inside the outer vacuum bag  201  after applying a vacuum to the first  107  and second spaces  115 . 
     In one embodiment of the step  315  of the method  300 , the hollow composite assembly  205  and at least one inner vacuum bag(s)  203 ,  204  are heated between ambient temperature and 250° C. inside the outer vacuum bag  201  after applying a vacuum to the first  107  and second spaces  115 . 
     In one embodiment of the step  315  of the method  300 , contact heating is used for heat processing the vacuum assembly  137 , which includes the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204 . The wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  are conformed to the internal surface  213  of the mold  220 , forming the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 , and the wall(s)  208 ,  210  of the j at least one inner vacuum bag(s)  203 ,  204  into a shape that is the negative image of the inner surface  213  of the mold  220 . 
     Hereinafter, “contact heating” means direct, intimate contact heat processing of the vacuum assembly  137  by a heating source other than the mold  220 . The heating source may be any heating tool capable of ballistically heating the vacuum assembly  137 , so that the mold  220  does not have to be cycled between the upper and lower temperature ranges, e.g. between ambient temperature and 250° C. in order to heat process the contact surface  126  of the vacuum assembly  137 . 
     In one embodiment of the step  315  of the method  300 , heating the vacuum assembly  133  that includes the hollow composite assembly  205  and j at least one inner vacuum bag(s)  203 ,  204  in the outer vacuum bag  201  is faster than heating apparatus  200 , that includes the mold  220 , when using the same heat source, because this avoids having to heat the mold  220 , which may have considerably more mass than the hollow composite assembly  205  and at least one inner vacuum bag(s)  203 ,  204  in the outer vacuum bag  201 . 
     In one embodiment, the “Hot” contact surface  126  of the vacuum assembly  137  is the wall  202  of the outer vacuum bag  201  and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 . The wall  202  of the outer vacuum bag  201  and the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205  are conformed to an internal surface  213  of the mold  220 , so that a shape of the wall  202  of the outer vacuum bag  201 , the i bondable layer(s) L 1 , L 2 , L 3  . . . , L (I−1) , L I  of the first and second types of the hollow composite assembly  205 , and the at least one wall(s)  208 ,  210  of the j inner vacuum bag(s)  203 ,  204  becomes the negative image of the internal surface  213  of the mold  220  when a vacuum is reapplied to conform the outer surface  126  of the vacuum assembly  137  to the exact shape of the inner surface  213  of the mold  220  heat processing. 
     In one embodiment, the vacuum assembly  137  is returned to the mold  220  for a second heat processing, during which vacuum is reapplied to the first space  107  and second space  115  to conform the outer surface  126  of the vacuum assembly  137  to the inner surface  213  of the mold  220 . 
     Hereinafter “Hot” means heat processing the contact surface  126  of the wall  202  of the outer vacuum bag  201  so that it has a temperature between ambient and 250° C. 
     In one embodiment of the step  315  of the method  300 , a pressure inside the outer vacuum bag  201  is reduced to less than atmospheric pressure, so that the j at least one inner vacuum bag(s)  203 ,  204  expands. 
     The foregoing description of the embodiments of this invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying embodiments.