Aspects of the present disclosure are directed to a three-dimensional joint and/or formation thereof, such as by 3D-printing the joint. The joint is provided with an interface region having a curable material in a curable state. The joint is positioned with the interface region in contact with a joinable member, and the interface region is cured to form a bond between the joint and the joinable member. Such an approach may, for example, involve forming a mechanical and/or chemical bond with the joint. Further, by utilizing such a joint (e.g., in a 3D-printed form), complex structural components can be formed from a curable material that can be partially cured with structures formed therein, and cured further to create the bond.

A composite radius filler material is provided. The composite radius filler includes a resin, a first group of fibers dispersed within the resin, and a second group of fibers dispersed within the resin. The first group of fibers has a first length configured to facilitate orientation in a longitudinal direction. The second group of fibers has a second length that is shorter than the first length, with the second group of fibers configured to facilitate random orientation in a transverse direction.

A method and apparatus for fabricating a composite structure. The method comprises defining a shape for the composite structure with a first face sheet. The method places core sections on the shape defined by the first face sheet. The method places an adhesive in a group of joint cavities. The method places a second face sheet on the core sections placed on the first face sheet, wherein the first face sheet, the core sections, and the second face sheet, define a structural assembly in which the group of joint cavities are present. The method cures the structural assembly with the adhesive in the group of joint cavities to fabricate the composite structure in which the adhesive fills the group of joint cavities when the adhesive is cured.

A high-strength structural joint is provided. The high-strength structural joint includes a first component of a first material, a second component of a second material. The second component of the second material defines a channel. The high-strength structural joint further includes a third component of a third material. A chemical bond joins the first component of the first material and the third component of the third material in the channel and the channel mechanically retains the third component of the third material.

An apparatus includes a first thermoset layer that includes a first fibrous material embedded in a first thermoset matrix. The apparatus also includes a second thermoset layer that includes a second fibrous material embedded in a second thermoset matrix. The second thermoset layer is coupled to the first thermoset layer to form a joint. Further, a gap is defined between the first thermoset layer and the second thermoset layer. The apparatus also includes a thermoplastic filler that is made from a thermoplastic material. The thermoplastic filler is positioned within the gap.

A material joint connecting an internal spar or baffle to panel walls of inflatable structures. The material joint is formed by a folded center strip and a pair of side strips. The side edges of the center strip are folded to form an initial T-shaped cross-section having a middle section, two side sections formed by a first bend, and two overlapping end sections formed by a second bend. The middle section is fused directly to the facing surface of the panel wall and the overlapping end sections are fused together to extend perpendicularly from the middle section. The end strips overlap the center strip with part of the end strips fused to the side sections of the center strip and part fused directly to the panel wall. The spar or baffle is connected to the fused overlapping end sections of the center strip. Under the internal air pressure of the inflated structure, the side sections bow and arc under tension from the connected spar or baffle and the middle section acts as a bridge to lift and flatten the exterior surface of the panel wall across its width.

Systems and methods are provided for blade-and-slot panel affixation. One embodiment is a method. The method includes cutting a first slot into a first composite panel that includes a core between two facesheets. The first slot penetrates through the core of the first composite panel. The method also includes cutting a second slot into a second composite panel that includes a core between two facesheets. The second slot penetrates through a facesheet of the second composite panel as well as the core of the second composite panel. The method further includes inserting a blade into the first slot, and inserting the blade into the second slot.

A thermoplastic composite structure is produced by extruding a bead of composite material to a desired cross sectional shape. An extruder extrudes the polymer bead containing reinforcing fibers, using a low compression first extruder stage where the polymer is mixed and de-gassed, and a high compression second stage where the polymer is consolidated and extruded. The cross sectional profile of the polymer bead may be altered using a variable extruder gate.

A composite radius filler material is provided. The composite radius filler includes a resin, a first group of fibers dispersed within the resin, and a second group of fibers dispersed within the resin. The first group of fibers has a first length configured to facilitate orientation in a longitudinal direction. The second group of fibers has a second length that is shorter than the first length, with the second group of fibers configured to facilitate random orientation in a transverse direction.

The disclosure relates to reversible bonded structural joints using active adhesive compositions that can allow for dis-assembly, repair, and re-assembly. The disclosure is particularly directed to the adhesive composition material, irrespective of the type of the substrate(s) being joined. The adhesive composition can include any thermoplastic adhesive material that can be remotely activated for targeted heating of just the adhesive composition (e.g., and not the surrounding substrates being joined) via the inclusion of electromagnetically excitable particles in the adhesive composition. The substrates can be any metal material, any composite material, any hybrid material, or otherwise. The disclosed adhesive compositions allow for recyclability of parts at the end of their lifetime and repair/replacement of parts during their lifetime.