Verifiable Quick Patch Repair for Composite Structures

Abstract

A method for patching a depression in a composite parent structure. The method comprises: inserting an insert in the depression; placing a composite patch having a multiplicity of curved flexible members on one side of the composite parent structure in a position where a central portion of the composite patch overlies the insert and the flexible members confront opposing portions of the composite parent structure providing adhesive between the composite patch, the insert, and the composite parent structure; pressing the composite patch against the composite parent structure with sufficient pressure to force the flexible members to conform to the shape of the composite parent structure; and while the flexible members are in a stressed state, curing the adhesive in a manner that causes the flexible members to bond to the parent structure.

1 . A composite structure comprising:
 a parent structure having a depression, said parent structure being made of composite material;   an insert in said depression, said insert being made of composite material; and   a patch bonded by adhesive to one side of said parent structure and one side of said insert, said patch being made of composite material, wherein said patch comprises a central portion and a multiplicity of pre-stressed members that extend outwardly from an outermost portion of said central portion of said patch, wherein said central portion of said patch is directly bonded to said one side of said insert by adhesive therebetween, and each of said multiplicity of pre-stressed members is directly bonded to opposing portions of said one side of said parent structure by adhesive therebetween, each pre-stressed member of said multiplicity being in a flexed state with a potential to deform toward an unflexed state in the event that a strength of the bond between that pre-stressed member and an opposing portion of said one side of said parent structure becomes zero.   
     
     
         2 . The composite structure as recited in  claim 1 , wherein said patch further comprises an innermost portion having a single opening, said innermost portion being bonded to said insert and not to said parent structure, and each of said multiplicity of pre-stressed members being bonded to said parent structure and not to said insert. 
     
     
         3 . The composite structure as recited in  claim 1 , further comprising a scrim disposed in the adhesive that bonds said patch to said parent structure. 
     
     
         4 . The composite structure as recited in  claim 1 , further comprising adhesive disposed in slits between adjacent pre-stressed members of said multiplicity. 
     
     
         5 . The composite structure as recited in  claim 1 , wherein said composite structure is part of an aerial vehicle. 
     
     
         6 . The composite structure as recited in  claim 1 , wherein said insert comprises a central opening, said central opening being closed by a plug and not by a bolt. 
     
     
         7 . A composite structure comprising:
 a parent structure having a depression, said parent structure being made of composite material;   an insert in said depression, said insert being made of composite material; and   a patch bonded by adhesive to one side of said parent structure and one side of said insert, said patch being made of composite material, wherein said patch comprises a central portion and a multiplicity of pre-stressed members that extend outwardly from an outermost portion of said central portion of said patch and are separated by slits, wherein said central portion of said patch is directly bonded to said one side of said insert by adhesive therebetween, and each of said multiplicity of pre-stressed members is directly bonded to opposing portions of said one side of said parent structure by adhesive therebetween and has the property that at least a portion of the pre-stressed member will deform toward an unflexed state in the event that a bond strength between said portion of said pre-stressed member of said multiplicity and an opposing portion of said one side of said parent structure changes from a non-zero value to zero.   
     
     
         8 . The composite structure as recited in  claim 7 , wherein said patch further comprises an innermost portion having a single opening, said innermost portion being bonded to said insert and not to said parent structure, and each of said multiplicity of pre-stressed members being bonded to said parent structure and not to said insert. 
     
     
         9 . The composite structure as recited in  claim 7 , further comprising a scrim disposed in the adhesive that bonds said patch to said parent structure. 
     
     
         10 . The composite structure as recited in  claim 7 , wherein said insert comprises a central opening, said central opening being closed by a plug and not by a bolt. 
     
     
         11 . A method for patching a depression in a composite parent structure, said method comprising:
 inserting an insert in the depression;   placing a composite patch having a multiplicity of curved flexible members on one side of the composite parent structure in a position where a central portion of the composite patch overlies the insert and the flexible members confront opposing portions of the composite parent structure disposed around the insert;   providing adhesive between the composite patch and the insert, and between the composite patch and the composite parent structure; and   pressing the composite patch against the composite parent structure with sufficient pressure to force the flexible members to conform to the shape of the surface of the opposing portions of the composite parent structure while the adhesive therebetween is curing.   
     
     
         12 . The method as recited in  claim 11 , wherein the flexible members of the composite patch become less curved or straight during said pressing step. 
     
     
         13 . The method as recited in  claim 11 , further comprising non-destructive evaluation of the integrity of bond lines between the flexible members of the composite patch and the opposing portions of the composite parent structure. 
     
     
         14 . The method as recited in  claim 11 , wherein said pressing step comprising applying pressure using mechanical force. 
     
     
         15 . The method as recited in  claim 11 , wherein said pressing step comprising applying pressure using magnetic force. 
     
     
         16 . The method as recited in  claim 11 , wherein said pressing step comprising applying vacuum pressure. 
     
     
         17 . The method as recited in  claim 11 , further comprising placing a bladder over said composite patch, wherein said pressing step comprises applying pressure to said bladder. 
     
     
         18 . A method for patching a depression in a composite parent structure, said method comprising:
 inserting an insert in the depression;   placing a composite patch having a multiplicity of curved flexible members on one side of the composite parent structure in a position where a central portion of the composite patch overlies the insert and the flexible members confront opposing portions of the composite parent structure disposed around the insert;   providing adhesive between the composite patch and the insert, and between the composite patch and the composite parent structure;   pressing the composite patch against the composite parent structure with sufficient pressure to force the flexible members to conform to the shape of the surface of the opposing portions of the composite parent structure so that the volumes of space between the flexible members and the composite parent structure are filled with adhesive; and   curing the adhesive while the flexible members are conformed to the shape of the surface of the opposing portions of the composite parent structure in a manner that causes the flexible members to bond to the parent structure.   
     
     
         19 . The method as recited in  claim 18 , wherein after the flexible members have been bonded to the parent structure by said curing process, each flexible member is in a respective pre-stressed flexed state with a potential to deform toward an unflexed state in the event that a strength of the bond between that flexible member and an opposing portion of said parent structure becomes zero. 
     
     
         20 . The method as recited in  claim 18 , further comprising placing randomized fibers within the adhesive before the adhesive is cured.