Methods for combining components of varying stages of cure

Abstract

The present invention provides a method of fabricating a composite structure from components of varying stages of cure while reducing the steps associated with the fabrication process of infusing, curing, and bonding composite materials to form a hybrid unitized structure. The method provides a pre-cured stiffener and a pi-preform having a clevis and a base portion. The pre-cured stiffener may be inserted into the clevis of the pi-preform to form a composite structure assembly. The composite structure assembly may be infused with a resin system at the time of cure and bonded to a second composite structure to form a hybrid unitized structure.

What is claimed is: 
     
         1 . A method of fabricating a composite structure from components of varying stages of cure, comprising the steps of:
 providing a stiffener component;   providing a dry fabric component;   combining the stiffener component and the dry fabric component to form an assembly, wherein the stiffener component provides structural support to the assembly;   infusing the assembly with resin to yield an infused assembly; and   curing the infused assembly to yield a cured assembly.   
     
     
         2 . The method of  claim 1 , further comprising the step of bonding the cured assembly with a component to form a hybrid unitized structure. 
     
     
         3 . The method of  claim 1 , wherein the stiffener component is fabricated from a composite material. 
     
     
         4 . The method of  claim 1 , wherein the stiffener component is (i) L-shaped or (ii) J-shaped 
     
     
         5 . The method of  claim 1 , wherein the dry fabric component is a three-dimensional woven pi-preform, wherein said pi-preform contains a clevis configured to receive an edge of the stiffener component. 
     
     
         6 . The method of  claim 3 , wherein the stiffener component is fabricated from a carbon-fiber composite material. 
     
     
         7 . The method of  claim 3 , wherein the stiffener component is fabricated from a glass-fiber composite material. 
     
     
         8 . The method of  claim 1 , wherein the stiffener component is fabricated from a metal. 
     
     
         9 . The method of  claim 5 , further comprising the steps of: (i) wrapping a resin film around a first edge of said stiffener component; and (ii) inserting the first edge of said stiffener component into the clevis of said pi-preform. 
     
     
         10 . The method of  claim 9 , further comprising the steps of: (i) wrapping a resin film around a second edge of said stiffener component; and (ii) inserting the second edge of said stiffener component into the clevis of the second pi-preform. 
     
     
         11 . The method of  claim 2 , wherein the component comprises Glass Laminate Aluminum Reinforced Epoxy. 
     
     
         12 . The method of  claim 1 , wherein the dry fabric component comprises at least one of: (1) glass-fiber; (2) carbon-fiber; or (3) para-aramid synthetic fiber. 
     
     
         13 . A method of fabricating a composite structure from components of varying stages of cure, comprising the steps of:
 providing a pre-cured composite stiffener;   providing a dry fabric component having a base portion and a clevis configured to receive the pre-cured composite stiffener, wherein the clevis is substantially perpendicular to the base portion;   wrapping a first film adhesive around a first edge of said pre-cured stiffener;   wrapping a first resin film around the first edge of said pre-cured stiffener;   inserting the first edge of said pre-cured composite stiffener into the clevis of the dry fabric component to form a composite structure assembly;   applying a second film adhesive to a surface of the dry fabric component;   applying a second resin film to the base portion of the dry fabric component;   securing the pre-cured stiffener substantially perpendicular to the base portion of the dry fabric component, wherein the pre-cured stiffener provides structural support to the composite structure assembly;   applying a film adhesive to the exterior base portion of the dry fabric component   securing the pre-cured stiffener with dry fabric component to another substrate to which it will bond;   infusing the composite structure assembly by heating the assembly to a first temperature for a first period of time; and   curing the composite structure assembly by increasing the heat to a second temperature, wherein the second temperature is greater than the first temperature.   
     
     
         14 . A method of fabricating a composite structure from components of varying stages of cure, comprising the steps of:
 providing a pre-cured composite stiffener;   providing a dry fabric component having a base portion and a clevis configured to receive the pre-cured composite stiffener, wherein the clevis is substantially perpendicular to the base portion;   wrapping a first resin film around a first edge of said pre-cured stiffener;   inserting the first edge of said pre-cured composite stiffener into the clevis of the dry fabric component to form a composite structure assembly;   applying a second resin film to a surface of the dry fabric component;   securing the pre-cured stiffener substantially perpendicular to the base portion of the dry fabric component, wherein the pre-cured stiffener provides structural support to the composite structure assembly;   infusing the composite structure assembly; and   curing the composite structure assembly.   
     
     
         15 . The method of  claim 14 , further comprising the steps of bonding composite structure assembly with a component to form a hybrid unitized structure. 
     
     
         16 . The method of  claim 14 , wherein the dry fabric component comprises at least one of: (1) glass-fiber; (2) carbon-fiber; or (3) para-aramid synthetic fiber. 
     
     
         17 . The method of  claim 14 , further comprising the steps of: (i) wrapping a resin film around a second edge of said stiffener component; and (ii) inserting the second edge of said stiffener component into the clevis of the second pi-preform. 
     
     
         18 . The method of  claim 15 , wherein the component comprises Glass Laminate 
     
     
         19 . The method of  claim 14 , wherein the second resin film has a weight that is different than the third resin film. 
     
     
         20 . A method of fabricating a composite structure from components of varying stages of cure, comprising the steps of:
 providing a pre-cured composite stiffener;   providing a dry fabric component having a base portion and a clevis configured to receive the pre-cured composite stiffener, wherein the clevis is substantially perpendicular to the base portion;   wrapping a first resin film around a first edge of said pre-cured stiffener;   inserting the first edge of said pre-cured composite stiffener into the clevis of the dry fabric component to form a composite structure assembly;   applying a second resin film to a surface of the dry fabric component;   securing the pre-cured stiffener substantially perpendicular to the base portion of the dry fabric component, wherein the pre-cured stiffener provides structural support to the composite structure assembly;   infusing the composite structure assembly by heating the assembly to a first temperature for a first period of time; and   curing the composite structure assembly by increasing the heat to a second temperature, wherein the second temperature is greater than the first temperature.   
     
     
         21 . The method of  claim 20 , wherein (i) the first temperature is between 150 and 200 degrees Fahrenheit, (ii) the second temperature is between 200 and 300 degrees Fahrenheit, (iii) the first period of time is between 10 and 25 minutes, and (iv) the second period of time is between 250 and 350 minutes.