Patent ID: 8691037

Claim:
A method for fabricating a one-piece composite barrel section, comprising the following steps: (a) molding a plurality of mandrel segments made of composite material, each mandrel segment having a plurality of longitudinal grooves on its outer circumferential surface, each groove having a contoured profile in cross section determined by axial ribs on an interior surface of a mold, the mandrel segments being made of composite material comprising reinforcing fibers that follow the contours of the grooves in a manner that increases the coefficient of thermal expansion in a hoopwise direction in the areas of the grooves as compared to the coefficient of thermal expansion in the hoopwise direction in ungrooved areas of the mandrel; (b) separating each mandrel segment from the mold interior surface; (c) arranging the plurality of mandrel segments to form a mandrel; (d) laying a composite ply assembly around the mandrel; and (e) raising the temperature and pressure within a volume surrounding the composite ply assembly, the temperature increase being sufficient to cause the circumference of said mandrel to expand, the mandrel and the composite ply assembly having a not insubstantial difference in coefficients of thermal expansion in a hoopwise direction and an insubstantial difference in coefficients of thermal expansion in a lengthwise direction, the coefficient of thermal expansion of the mandrel in said hoopwise direction being greater than the coefficient of thermal expansion of said composite ply assembly in said hoopwise direction such that one or more plies of the composite ply assembly is stretched during step (e).