In the present disclosure, a method may include forming a three-dimensional composite fiber pre-form by three-dimensionally weaving a plurality of composite fibers. The composite fiber pre-form includes a plurality of open cells formed adjacent to and interlocked with each other, and a composite fiber forms at least a portion of a first side of a first open cell and at least a portion of a second side of a second open cell. The first open cell and the second open cell are adjacent to and interlocked with each other.

A honeycomb sandwich structure in which moisture absorption deformation can be sufficiently suppressed and a method for manufacturing the same are provided. The honeycomb sandwich structure includes: a honeycomb core having a recess in a mesh of a carbon fiber fabric; a pair of face plates; a resin layer which fills a part of the recesses; and a water-impermeable film which covers an exposed area including surfaces of the resin layer and the honeycomb core, wherein the recess includes an unfilled part, the unfilled part is a part of the recess that is closer to the opening of the recess, and the unfilled part is not filled with the resin layer.

Provided are splices, comprising honeycomb cores and adhesive layers with tie clips supporting the honeycomb cores. Also provided are methods of forming such splices. Each tie clip includes two legs and a bridging portion joining the legs. When forming a splice, an adhesive layer is positioned between two honeycomb cores. One leg of the tie clip is inserted into the full cell of one honeycomb core, while the other leg is inserted into the full cell of the other honeycomb core. The bridging portion extends across the adhesive layer. While curing the adhesive layer, the tie clip supports the honeycomb cores with respect to each other and maintains their orientation. The tie clip becomes a part of the splice. The tie clip may be buried in the honeycomb cores without extending above the first face of the splice.

A method of producing a core for a composite panel along a continuous production line is disclosed. The method includes the steps of providing a thermoplastic sheet of material onto the production line and vacuum forming the thermoplastic sheet of material into alternating pairs of matching shapes, providing the thermoplastic sheet of material with alternating pairs of matching shapes onto upper and lower conveyor belts that are operating at lower speeds than the production line causing the pairs of matching shapes to bunch up and form a honeycomb structure, and cutting the honeycomb structure into discrete sections with spaces therebetween. A plurality of reinforced plastic bands with gaps therebetween are provided and the honeycomb structure is aligned with the gaps. The plurality of reinforced plastic bands and the honeycomb structure are secured together.

A composite core assembly includes a composite core structure having internal material interfaces and an attachment rail coupled to the composite core structure. The attachment rail includes a first planar surface and a second planar surface adjoined with the first planar surface. The first planar surface is arranged parallel to an internal material interface plane of the composite core structure, and the first planar portion is at least partially integrated into the composite core structure in an internal material interface plane. At least a portion of the first planar surface extends beyond a perimeter surface of the composite core structure, and the second planar surface is configured to attach to the surrounding support member. The core material does not have net edge facets or flat edges positioned next to surrounding structure, and/or may not have a structure arranged parallel to the adjacent support structure to attach to the support structure.

A honeycomb core includes carbon fiber having four or more different fiber directions, and when a ribbon direction is set as an X axis direction, a cell width direction is set as a Y axis direction, and a direction that is orthogonal to the ribbon direction and the cell width direction is set as a Z axis direction. A condition in which angles formed by the X axis direction and the respective fiber directions of the carbon fiber are set at 45 degrees, 0 degrees, 45 degrees, and 90 degrees is set as a reference condition. The respective fiber directions are rotated from the reference condition by a fixed rotation angle so that none of the fiber directions are parallel to the X axis direction.

An anti-icing honeycomb core composite manufactured by forming an electromagnetic wave absorption layer by using dielectric fiber, molding the electromagnetic wave absorption layer into a honeycomb core structure by using a molded part including a first base, a second base, and an inner block, hardening the honeycomb core structure, and removing the molded part. The molding step includes first stacking, on the first base including a plurality of grooves in which the inner blocks each having a hexagonal column shape are able to be seated, a plurality of the inner blocks and a plurality of the electromagnetic wave absorption layers as the honeycomb core structure so that the electromagnetic wave absorption layer is disposed between the plurality of inner blocks, and second stacking covering the inner blocks and the electromagnetic wave absorption layers stacked on the first base with the second base having the same shape as the first base.

A composite sandwich panel comprises a first composite skin, a second composite skin, a hollow cell core between the first composite skin and the second composite skin, and a first over-crush edge region with a first edge. The first edge has a first thickness at least 40% less than a nominal thickness of the composite sandwich panel. The first over-crush edge region has a length of at least 0.25 inches over which a thickness of the composite sandwich panel decreases.

Systems and methods are provided for septa for acoustic cells. One embodiment is a method that includes fabricating a septum of a cell of an acoustic panel, by heating a material into a molten material, depositing the molten material to form a lower chamber of the septum that extends vertically upwards and includes an entry, iteratively depositing layers of the molten material, each layer comprising a filament at the entry that includes overhangs with respect to vertically adjacent layers, and forming openings at locations of the overhangs.

A composite core assembly includes a composite core structure having internal material interfaces and an attachment rail coupled to the composite core structure. The attachment rail includes a first planar surface and a second planar surface adjoined with the first planar surface. The first planar surface is arranged parallel to an internal material interface plane of the composite core structure, and the first planar portion is at least partially integrated into the composite core structure in an internal material interface plane. At least a portion of the first planar surface extends beyond a perimeter surface of the composite core structure, and the second planar surface is configured to attach to the surrounding support member. The core material does not have net edge facets or flat edges positioned next to surrounding structure, and/or may not have a structure arranged parallel to the adjacent support structure to attach to the support structure.