Advanced composite aerostructure article having a braided co-cured fly away hollow mandrel and method for fabrication

Abstract

An article of fiber-reinforced composite material formed by co-curing a lay up under a cycle of heat and pressure. The lay up comprises a first uncured composite layer having at least one uncured resin-impregnated laminate layer. At least one hollow mandrel is provided comprised of a stiffened braided fabric and having an upper, a lower and side surfaces. The mandrel is secured on the upper surface of the first composite layer with the lower surface thereof in engagement with the upper surface of the first composite layer. A second uncured composite layer is positioned over the upper and side surfaces of the hollow mandrel and at least a portion of the upper surface the first uncured composite layer. The second uncured composite layer has at least one uncured resin-impregnated layer. After the cycle of heat and pressure in an autoclave, the hollow mandrel is retained in the co-cured article.

1 - 16 . (canceled) 
     
     
         17 . A method of fabricating an article from fiber-reinforced composite material comprising:
 assembling on a composite bond surface a first uncured composite layer in the shape of at least one surface of the article, the first composite layer having an upper surface and at least one uncured resin-impregnated laminate layer;   providing at least one hollow mandrel, the at least one hollow mandrel comprised of a braided fabric having upper, lower and side surfaces;   securing on the upper surface of the first composite layer the hollow mandrel with the lower surface thereof in engagement with the upper surface of the first composite layer;   assembling a second uncured composite layer on the bond surface over the upper and side surfaces of the at least one hollow mandrel and at least a portion of the upper surface the first uncured composite layer, the second uncured composite layer having at least one uncured resin-impregnated layer; and   subjecting the lay up assembled on the composite bond surface to a cycle of predetermined pressure and temperature to cure the resin-impregnated layers so as to form a unitary co-cured one-piece article, wherein the hollow mandrel is retained in the co-cured article.   
     
     
         18 . The method of  claim 17 , wherein the hollow mandrel is impregnated with a resin. 
     
     
         19 . The method of  claim 17 , wherein the hollow mandrel is pre-cured to a predetermined shape. 
     
     
         20 . The method of  claim 17 , wherein the cross-sectional shape of the hollow mandrel varies along a longitudinal extent thereof. 
     
     
         21 . The method of  claim 17 , wherein the step of providing at least one hollow mandrel, comprises providing a pair of hollow mandrels, and wherein the step of securing on the upper surface of the first composite layer the hollow mandrel comprises securing the pair of mandrels on the first composite layer in a laterally spaced-apart configuration. 
     
     
         22 . The method of  claim 17 , further comprising:
 prior to the step of subjecting the lay up assembled on the composite bond surface to a cycle of predetermined pressure and temperature, assembling on a composite bond surface a third uncured composite layer in the shape of at least a second surface of the article, the third composite layer having at least one uncured resin-impregnated laminate layer;   providing a second hollow mandrel, the second hollow mandrel comprised of a braided fabric having upper, lower and side surfaces; and   securing on the upper surface of the first composite layer the hollow mandrel with the lower surface thereof in engagement with the upper surface of the first composite layer; and   assembling a fourth uncured composite layer on the bond surface over the upper and side surfaces of the second hollow mandrel and at least a portion of the upper surface the third uncured composite layer, the fourth uncured composite layer having at least one uncured resin-impregnated layer.