Described herein are methods and systems for manufacturing composite stringers using independently movable pallets with independent vacuum controls. Specifically, a stringer forming system comprises a base plate and a plurality of sets of pallets (e.g., two or more sets of pallets), slidably coupled to the base plate and forming an adjustable cavity. Each pallet comprises a primary vacuum zone, fluidly connected to a separate vacuum port. The system allows for independent application of a reduced pressure to the primary vacuum zone of each pallet. For example, a reduced pressure is applied only to pallets that are already covered with a composite layup and to pallets that are being covered. Any pallets that are exposed are kept at an ambient pressure and decoupled from a vacuum source, thereby reducing the vacuum leakage through the overall system. As the composite layup is being formed over new pallets, these new pallets are subjected to the reduced pressure.

Systems and methods are provided for demolding a composite part from a mandrel. The method includes mechanically coupling a first arm of an extraction tool to a first arcuate portion of a composite part that has been hardened onto a mandrel, mechanically coupling a second arm of an extraction tool to a second arcuate portion of the composite part, and separating the composite part from the mandrel by iteratively performing the following operations until the composite part no longer contacts the mandrel: elastically straining the first arcuate portion of the composite part via the first arm, and elastically straining the second arcuate portion of the composite part via the second arm.

A three-dimensional auxetic structure, comprising a plurality of adjoining hollow cells, each hollow cell having cell walls and a transversal cross section of the plurality hollow cells following a two-dimensional auxetic pattern, each cell wall comprising folding lines parallel to a plane containing the auxetic pattern such that peaks and valleys are defined in the cell walls and the cell walls being foldable along the folding lines.

A composite panel includes a plurality of segments, wherein each segment includes a plurality of reinforcement plies such as carbon fiber plies. Collimated fiber bands (e.g., carbon fibers) within each reinforcement ply are oriented in a single direction, which can be, for example, 0°, 45°, 90°, and −45°. Each segment can include a stack of reinforcement plies, wherein the collimated fiber bands of each reinforcement ply are oriented in one of these directions. The orientations of the collimated fiber bands that form the reinforcement plies in a stack determine a stiffness of the stack and the segment that includes the stack. The stiffness of each segment is controlled to reduce a stiffness mismatch between adjacent segments that form the composite panel, thereby reducing separation of the segments during use.

Systems and methods are provided for fabricating composite parts. One embodiment is a method for fabricating a composite part. The method includes forming a skin panel preform comprising fiber reinforced material, disposing rigid end caps at the skin panel preform at end locations of stringer preforms that will be placed at the skin panel, locating the stringer preforms at the skin panel preform via the rigid end caps, and anchoring the stringer preforms to the skin panel preform.

A stiffener for an aircraft assembly is disclosed. The stiffener provides structural stability to the aircraft assembly. The stiffener has a first stiffener part having a planar web portion and a second stiffener part arranged with the first stiffener part. The second stiffener part includes a corrugated web portion having a corrugation. The present application also relates to an aircraft assembly, a fuselage for an aircraft, an aircraft and a method of forming a stiffener for an aircraft assembly.

An aerostructure assembly that includes an aerostructure (e.g., a resin pressure molded structure) and a coupling assembly is disclosed. The aerostructure includes an outer shell and a female receiver located within an interior of the outer shell. The coupling assembly includes a coupling and a beam that extends from this coupling. The beam is disposed within the female receiver, including where at least part of the coupling is positioned beyond an open end of the outer shell. The shape of the female receiver may retain the aerostructure to the beam in at least one direction/dimension. One or more fasteners may be utilized to attach the aerostructure to the beam. The coupling may be formed from one or more metals, and in any case, accommodates attachment of the aerostructure assembly to a flight vehicle.

There is provided a forming apparatus for forming a high contour composite structure. The forming apparatus includes an upper die and a lower die between which a composite charge is formed. The forming apparatus further includes a plurality of load cells, a control system, and an overlay tool assembly coupled to the upper die. The overlay tool assembly has scalloped sections positioned between pairs of the plurality of load cells, and positioned against portion(s) of the composite charge. The composite charge has ply discontinuity features through the one or more portions. The overlay tool assembly denies pressure and a through thickness compaction to the one or more portions of the composite charge during a forming process, to allow one or more plies in the one or more portions to move after the forming process, and to enable in-plane bending of the high contour composite structure in post-forming operations.

Provided are a composite material structure obtained by joining composite materials with resin-impregnated reinforcing fibers, for which appropriate lightning proofing measures are taken, and a method for manufacturing the composite material structure. The composite material structure includes a first composite material, a second composite material, and a low-conductivity material. The first composite material includes a conductive first reinforcing fiber and a first resin impregnated into the first reinforcing fiber. The second composite material is integrated with the first composite material, and has a conductive second reinforcing fiber and a second resin impregnated into the second reinforcing fiber. The low-conductivity material has an electrical resistance that is lower than that of the first resin and the second resin and a low conductivity that is greater than or equal to the first reinforcing fiber and the second reinforcing fiber, and electrically connects the first reinforcing fiber to the second reinforcing fiber.

A tool for making contoured composite hat stringers allows control of stringer wrinkling. The tool includes a set of first openings that allow the tool to flex during contouring of the stringer, and a set of second openings into which portions of the composite charge may strain during the contouring.