A method is disclosed for manufacturing connecting members for connecting an aircraft wing to a center wing box, using preforms. The method involves a step of manufacturing at least one preform made of composite material forming the connecting member, and a step of assembling the preform or preforms by heat treatment to form the connecting member. The manufacturing method makes it possible, simply and quickly, to manufacture a connecting member that contributes to the connection between a center wing box of an aircraft and a wing of the aircraft.

A method for surface preparation of composite substrates prior to adhesive bonding. A curable surface treatment layer containing blocked isocyanate compounds is applied onto a curable composite substrate, followed by co-curing. The surface treatment layer may be a resin layer without fibers or a removal peel ply composed of resin-impregnated fabric. After surface preparation, the composite substrate is provided with a chemically-active, bondable surface that can be adhesively bonded to another composite substrate to form a covalently-bonded structure.

Systems and methods are provided for fabricating gap fillers for composite parts. One exemplary system includes a controller that acquires a geometry for a gap filler that will occupy a volume at a joint between laminates of curable constituent material, subdivides the geometry of the gap filler into layers, and for each layer: identifies variations in width of the layer along a length of the gap filler, and generates instructions for trimming a web of curable constituent material to match the variations in width of the layer. The system also includes rollers that dispense webs of the curable constituent material, trimmers that trim the webs of the curable constituent material based on the instructions, and compaction rollers that compact the trimmed webs together to fabricate the gap filler.

Composite laminate structures are produced using partially cured parts. Partial curing of the parts is achieved by applying a catalyst to regions of the parts that are to be fully cured. These regions cure at a lower-than-normal temperature while remaining regions of the part remain uncured, allowing them to be co-bonded or co-cured to other structures.

A plugged stringer on a surface of a part, and a method and assembly for production of the plugged stringer. The plug has opposite first and second axial end faces. The plug also has a radially outer margin defined by a radially outer bottom face, radially outer first and second opposite side faces, and a radially outer top face. The plugged stringer also includes a covering overlaying the radially outer top face and the first and second opposite side faces of the plug and extending away from the plug along an axis to form a stringer having first and second segments delineated by the plug. The radially outer margin of the plug is at least partly covered by an adhesive. The radially outer bottom face is adhered to the surface of the part, and the covering is adhered to the radially outer first and second opposite side faces and the radially outer top face. The first and second segments of the stringer respectively define first and second fluid passages separated by the plug. The first fluid passage is fluidly isolated from the second fluid passage by the plug.

A molding apparatus for a loop structure includes a molding die within which both ends of an elongated structure are located in such a manner that the ends are in contact with each other, the elongated structure being formed of a rubber to which a peroxide cross-linking agent is added; a liftable housing including a lower part having an opening, the housing defining a containment space within which the molding die and the elongated structure are located when the housing is lowered; a degassing device configured to depressurize and degas the containment space; a heating device configured to heat the molding die in the containment space; a pressure device configured to pressurize the ends of the elongated structure with the use of the heated molding die in the containment space to proceed cross-linking reaction of the rubber, thereby bonding the ends of the elongated structure; and an elevating device configured to lift and lower the housing.

Composite laminate structures are produced using partially cured parts. Partial curing of the parts is achieved by applying a catalyst to regions of the parts that are to be fully cured. These regions cure at a lower-than-normal temperature while remaining regions of the part remain uncured, allowing them to be co-bonded or co-cured to other structures.

A method for bonding composite substrates includes coupling a first co-cure prepreg layer having a first off-set amine to epoxide molar ratio onto a surface of a first composite substrate and coupling a second co-cure prepreg layer having a second off-set amine to epoxide molar ratio onto a surface of a second composite substrate. The first and second composite substrates are cured to the first and second co-cure prepreg layers, respectively, using a first cure cycle (including B-stage and cure temperatures) to form a first and a second co-cure prepreg layer portion. The method further includes coupling the first co-cure prepreg layer portion to the second co-cure prepreg layer portion and applying a second cure cycle to cure the first co-cure prepreg layer portion of the first composite substrate to the second co-cure prepreg layer portion of the second composite substrate to form a monolithic covalently bonded composite structure.

Methods for manufacturing elongated structural elements are provided. Such methods provide composite material having optimal properties such as weight and strength which can be produced at much lower costs compared to conventional methods. Composite materials including such elements are also provided. In addition, commercial products incorporating such structural elements are provided.

Aircraft stringers having carbon fiber reinforced plastic (CFRP) material reinforced flanges are disclosed. An example stringer to be coupled to a skin of an aircraft comprises a flange. The flange includes a first portion of a first stiffening segment. The flange further includes a first portion of a second stiffening segment coupled to the first portion of the first stiffening segment. The flange further includes a CFRP reinforcement segment coupled to the first portion of the first stiffening segment and to the first portion of the second stiffening segment. The CFRP reinforcement segment strengthens the first portion of the first stiffening segment and the first portion of the second stiffening segment.