Abstract: Producing a composite structure involves providing a core structure having a folded configuration with fold valleys forming open channels extending along the valleys, and then forming a local reinforcement zone in the core structure itself, before applying any cover layer onto the core structure. The method may further involve applying two cover layers on two opposite sides of the core structure to form a composite sandwich structure, after the local reinforcement zone has been formed in the core structure. A core structure preferably has a local reinforcement zone formed by two molded bodies, e.g. of cured synthetic resin or foam, arranged form-fittingly on the opposite sides of the core.

Abstract: A composite sandwich structure is produced by providing a core structure, applying cover layers on opposite sides of the core structure, and forming an edge seal. The core structure has a folded cell structure with fold valleys forming continuous open channels with open ends and/or open channel sides at edges of the core structure. The channels extend along and are bounded between the fold valleys and the cover layers. The edge seal is formed to have a limited spatial volume in an edge region at an edge of the core structure, to close and seal open ends and/or open channel sides of the channels of the core, without an uncontrolled penetration of the seal material from the edge region to a greater depth into the open channels.

Abstract: A method and an apparatus facilitate the processing of a core structure for a composite sandwich structure. The core has an open three-dimensional structure and is not self-supporting due to an insufficient strength or stiffness. The method involves temporarily providing a support arrangement on the core structure to mechanically support and stabilize it, then subjecting the supported core structure to the desired processing, and then separating and removing the core structure and the support arrangement from one another. The processing can involve immersion into a processing liquid such as a curable resin, or mechanical machining operations. The support arrangement preferably includes a core impression that is surfacially form-fitting on a structured surface of the core structure. The apparatus includes a support arrangement including a core impression to be disposed on a surface of the core structure. The core impression may be formed of a polymer, a metal, or a casting material.

Abstract: Producing a local reinforcement in a core structure of a composite sandwich structure involves forming a hole in a cover layer and the core of the sandwich structure, forming a hollow space in the core with a diameter the same as or preferably larger than that of the hole, introducing a spatial bounding device through the hole into the hollow space, seating the spatial bounding device in the hollow space to contact outwardly against parts of the core preferably by outwardly expanding the device, and introducing a filler material into the spatial bounding device. A sandwich structure includes a core between cover layers, and a local reinforcement including a hole in at least one of the cover layers, a space in the core with a larger diameter than the hole, a spiral sleeve in the space, and a filler material inside the spiral sleeve.