Patent ID: 7384585

Claim:
A method for producing a dry preform for a composite material for use as a structural material, comprising the step of (a) providing a planar reinforcing filament assembly comprising a first fiber reinforcement layer and a second fiber reinforcement layer, the first fiber reinforcement layer including strands of fiber reinforcement extending straight along an axis, the second fiber reinforcement layer including strands of fiber reinforcement directed at an angle with respect to the axis, wherein the first fiber reinforcement layer covers half the area of the planar reinforcing filament assembly while the second reinforcement layer covers the entire area of the planar reinforcing filament assembly; (b) deforming the planar reinforcing filament assembly out of plane along with a curved axis to form a curved reinforcing filament assembly having the same curvature on the same plane; (c) deforming the curved reinforcing filament assembly where solely the second fiber reinforcement layer is formed out of the plane to form a first resultant reinforcing filament assembly having a flanged portion and an L-shaped cross-section; forming a second resultant reinforcing filament assembly having a flanged portion and a L-shaped cross-section through the steps (a)-(c); and holding together the first and second resultant reinforcing filament assemblies to form a dry preform having an L-shaped cross-section and a shape bent along the curved axis, in which the first fiber reinforcement layer including strands of fiber reinforcement directed along the curved axis and the second fiber reinforcement layer including strands of fiber reinforcement directed at an angle with respect to the curved axis extend throughout the dry perform.