Composite structure reinforcement utilizing thermal properties of forming elements

Abstract

Forming systems and assemblies as disclosed herein comprise a composite material comprising a structural component and a resin component combined with the reinforcing component. A forming element is disposed within the composite material and has a coefficient of thermal expansion that is greater than that of the composite material. The forming element is positioned to provide a desired integral structural reinforcement and/or surface feature to the composite. The composite material may comprise one or more passages extending from a surface thereof to the forming element. The composite material may be cured by heat to take a set configuration and then allowed to cool. The cooling of the composite material and the forming element enables the forming element to contract relative to the composite material and become delaminated therefrom to facilitate easy removal, and thereby provide an improved method and assembly for making structural reinforcing features in composite structures.

What is claimed: 
     
         1 . An assembly comprising:
 a composite material comprising a reinforcing component and a resin component combined with the reinforcing component; and   a forming element disposed within the composite material, wherein the forming element is made from a material having a higher coefficient of thermal expansion than the composite material.   
     
     
         2 . The assembly as recited in  claim 1  wherein the forming element is made from a material having a surface energy that is less than that of the composite material. 
     
     
         3 . The assembly as recited in  claim 1  wherein the composite material comprises one or more passages extending from a surface thereof to the forming element. 
     
     
         4 . The assembly as recited in  claim 1  wherein the composite material includes a surface feature positioned adjacent the forming element that is elevated relative to a surface of the composite material. 
     
     
         5 . The assembly as recited in  claim 1  wherein the surface feature is an integral reinforcing structure. 
     
     
         6 . The assembly as recited in  claim 1  wherein the forming element comprises a fluoropolymeric material. 
     
     
         7 . The assembly as recited in  claim 1  wherein the forming element comprises one or both of a conductive element and conductive material disposed therein. 
     
     
         8 . The assembly as recited in  claim 1  wherein the forming element comprises an open channel extending therethrough. 
     
     
         9 . The assembly as recited in  claim 1  wherein the forming element comprises body and a core disposed within the body, wherein the core has a degree of rigidity that is greater than the body. 
     
     
         10 . A method for making a composite structure comprising the steps of:
 a forming a composite panel comprising sheets of reinforcing material and a resin in contact with the sheets;   placing a forming element within the composite panel at a location where a hollow passage within the composite structure feature, the forming element being made from a solid material having a higher coefficient of thermal expansion than the composite panel, the composite panel and forming element forming an assembly;   treating the assembly to cure the composite panel to form the composite structure; and   causing the forming element to contract relative to the composite structure and become detached from the composite structure.   
     
     
         11 . The method as recited in  claim 10  wherein the forming element is made from a material having a low surface energy relative to the composite structure. 
     
     
         12 . The method as recited in  claim 10  comprising heating the forming element before the step of causing. 
     
     
         13 . The method as recited in  claim 12  wherein during the step of heating a heated liquid disposed within the forming element. 
     
     
         14 . The method as recited in  claim 12  where the forming element comprises a conductive element disposed therein, and wherein during the step of heating energy is directed to the conductive element. 
     
     
         15 . The method as recited in  claim 10  further comprising forming one or more passages extending from the surface of the composite panel to the forming element. 
     
     
         16 . The method as recited in  claim 10  wherein contracting is achieved by cooling the forming element. 
     
     
         17 . A method for forming a composite structure comprising a hollow passage extending therein comprising the steps of:
 inserting a rigid forming element within a composite panel where a hollow passage is desired, the composite panel being formed from reinforcing elements and resin, the forming element having a coefficient of thermal expansion greater than that of the composite panel and having a low surface energy relative to the composite panel;   subjecting the forming element to heat to expand the forming element;   curing the composite panel to form the composite structure;   cooling the forming element to detach the forming element from the composite structure; and   removing the forming member from the composite structure.   
     
     
         18 . The method as recited in  claim 17  further comprising forming one or more passages extending through the composite panel from the forming element to a surface of the composite panel. 
     
     
         19 . The method as recited in  claim 17  wherein the forming element comprises a rigid conductive core disposed within a surrounding body. 
     
     
         20 . The method as recited in  claim 17  wherein the forming element comprises a hollow passage extending therein.