Abstract: A system for making highly contoured composite stringers, including a flexible stringer assembly to support an uncured composite stringer; and a contoured mandrel to contour the uncured composite stringer into a highly contoured shape, wherein the contoured mandrel comprises one or more curvatures with a radius of 100 inches or less along at least one of an x, y, or z axis.

Abstract: Described herein are details for designing and manufacturing enhanced shock and impact resistant helicoidal lay-ups by combining nanomaterials, variable pitch and partial spirals, Thin unidirectional fiber plies, hybrid materials, and/or curved fibers within a ply. The helicoidal structures created in the prescribed manners can be tuned and pitched to desired wavelengths to dampen propagating shock waves initiated by ballistics, strike forces or foreign material impacts and can arrest the propagation of fractures including catastrophic fractures. These enhancements open the helicoidal technology up for use in such applications as consumer products, protective armor, sporting equipment, crash protection devices, wind turbine blades, cryogenic tanks, pressure vessels, battery casings, automotive/aerospace components, construction materials, and other composite products.

Abstract: Described herein are details for designing and manufacturing enhanced shock and impact resistant helicoidal lay-ups by combining nanomaterials, variable pitch and partial spirals, Thin unidirectional fiber plies, hybrid materials, and/or curved fibers within a ply. The helicoidal structures created in the prescribed manners can be tuned and pitched to desired wavelengths to dampen propagating shock waves initiated by ballistics, strike forces or foreign material impacts and can arrest the propagation of fractures including catastrophic fractures. These enhancements open the helicoidal technology up for use in such applications as consumer products, protective armor, sporting equipment, crash protection devices, wind turbine blades, cryogenic tanks, pressure vessels, battery casings, automotive/aerospace components, construction materials, and other composite products.

Abstract: Radius fillers for composite structures, composite structures that include the radius fillers, and systems and methods of forming the radius fillers. The systems and methods may be configured to create a pre-form that may be utilized to form a radius filler and/or to create a radius filler from the pre-form. The systems may include an apparatus configured to form the pre-form for the radius filler. This apparatus includes a composite tape source, a pre-forming structure, and a drive mechanism. The systems also may include an apparatus configured to form the radius filler. This apparatus includes a pre-form supply, a first radius filler die, a second radius filler die, and a die selection structure.

Abstract: A system for making highly contoured composite stringers, including a flexible stringer assembly to support an uncured composite stringer; and a contoured mandrel to contour the uncured composite stringer into a highly contoured shape, wherein the contoured mandrel comprises one or more curvatures with a radius of 100 inches or less along at least one of an x, y, or z axis.

Abstract: Radius fillers for composite structures and composite structures that include radius fillers are disclosed herein. The radius fillers include a plurality of lengths of composite tape. Each of the plurality of lengths of composite tape includes a respective plurality of lengths of reinforcing fibers and a resin material. The plurality of lengths of reinforcing fibers in each of the plurality of lengths of composite tape defines a fiber axis direction. Each of the plurality of lengths of composite tape defines a respective fiber axis direction that is based, at least in part, on material properties of a transition region defined by a plurality of plies of composite material that defines an elongate void space within which the radius filler is configured to extend. The composite structures include the radius fillers.

Abstract: Fluted core sandwich panels are joined together to form a composite structure. Variations in panel ends are accommodated by a core stiffener insert installed in a joint between ends of the panels.

Abstract: A hybrid softening strip for controlling stresses in a joint at low temperatures includes a layer of sacrificial material that can be tailored to fit the softening strip in the joint after the softening strip has been bonded to a structure.

Abstract: A method for assembling a composite wall assembly edge joint including laying up a first composite face sheet, laying up a first composite buildup pad having a first tapered section onto the first composite face sheet and positioning a composite flute core member, including a tapered first portion with a first inclined surface and a second inclined surface. First inclined surface is positioned onto the first tapered section of the first composite buildup pad and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet. The method also includes laying up a second composite buildup pad having a second tapered section with the second composite buildup pad spaced apart from the first composite buildup pad and having at least a portion of the second tapered section overlying the second inclined surface of the tapered first portion.

Abstract: A composite wall assembly edge joint including a first composite buildup pad having a first tapered section is secured to and extends along a first composite face sheet. A second composite buildup pad having a second tapered section is secured to and extends along a second composite face sheet, wherein the first and second composite buildup pads are positioned between spaced apart first and second composite face sheets. A composite flute core member includes a tapered first portion positioned between and secured to the first tapered section and to the second tapered section. A second portion of the composite flute core member extends in a direction away from the tapered first portion of the composite flute core member and is positioned between, extends along and is secured to the first and second composite face sheets.

Abstract: A composite wall assembly edge joint, includes a first composite buildup pad secured to a first composite face sheet with the first composite buildup pad having a first tapered section with a first inclined surface which extends in a first direction and having a second section which extends from the first tapered section with a second surface which extends in a second direction, different from the first direction, toward a first end of the first composite face sheet. The assembly further includes a composite flute core member, having a tapered first portion secured to the first tapered section; a second portion secured to the first composite face sheet; and a third portion which extends in the second direction, away from the tapered first portion, toward the first end of the first composite face sheet secured to the second section.

Abstract: Radius fillers for composite structures and composite structures that include radius fillers are disclosed herein. The radius fillers include a plurality of lengths of composite tape. Each of the plurality of lengths of composite tape includes a respective plurality of lengths of reinforcing fibers and a resin material. The plurality of lengths of reinforcing fibers in each of the plurality of lengths of composite tape defines a fiber axis direction. Each of the plurality of lengths of composite tape defines a respective fiber axis direction that is based, at least in part, on material properties of a transition region defined by a plurality of plies of composite material that defines an elongate void space within which the radius filler is configured to extend. The composite structures include the radius fillers.

Abstract: A composite wall assembly edge joint, includes a first composite buildup pad secured to a first composite face sheet with the first composite buildup pad having a first tapered section with a first inclined surface which extends in a first direction and having a second section which extends from the first tapered section with a second surface which extends in a second direction, different from the first direction, toward a first end of the first composite face sheet. The assembly further includes a composite flute core member, having a tapered first portion secured to the first tapered section; a second portion secured to the first composite face sheet; and a third portion which extends in the second direction, away from the tapered first portion, toward the first end of the first composite face sheet secured to the second section.

Abstract: A method for assembling a composite wall assembly edge joint including laying up a first composite face sheet, laying up a first composite buildup pad having a first tapered section onto the first composite face sheet and positioning a composite flute core member, including a tapered first portion with a first inclined surface and a second inclined surface. First inclined surface is positioned onto the first tapered section of the first composite buildup pad and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet. The method also includes laying up a second composite buildup pad having a second tapered section with the second composite buildup pad spaced apart from the first composite buildup pad and having at least a portion of the second tapered section overlying the second inclined surface of the tapered first portion.

Abstract: A composite wall assembly edge joint including a first composite buildup pad having a first tapered section is secured to and extends along a first composite face sheet. A second composite buildup pad having a second tapered section is secured to and extends along a second composite face sheet, wherein the first and second composite buildup pads are positioned between spaced apart first and second composite face sheets. A composite flute core member includes a tapered first portion positioned between and secured to the first tapered section and to the second tapered section. A second portion of the composite flute core member extends in a direction away from the tapered first portion of the composite flute core member and is positioned between, extends along and is secured to the first and second composite face sheets.

Abstract: Radius fillers for composite structures, composite structures that include radius fillers, and systems and methods of forming the same are disclosed herein. The methods include determining a transverse cross-sectional shape of an elongate void space, which extends within a transition region that is defined by a plurality of plies of composite material, and determining a material property field of the transition region. The methods further include forming the radius filler by combining a plurality of lengths of composite tape to define a radius filler cross-sectional shape, which corresponds to the transverse cross-sectional shape of the elongate void space, and orienting a plurality of lengths of reinforcing fiber in each of the plurality of lengths of composite tape based, at least in part, on the material property field of the transition region. The radius fillers include radius fillers with selectively oriented reinforcing fibers. The composite structures include the radius fillers.

Abstract: A composite radius filler having a varying cross-sectional shape is pre-conditioned before being pultruded through forming dies. The composite filler radius filler includes a tab ply having a varying width that is laminated onto a supporting, full width base ply.

Abstract: Method and apparatus for use in curing of a composite charge having an internal cavity. Apparatus includes a flexible bladder adapted to be placed in the cavity for applying pressure on the composite charge during curing. An end fitting is operatively coupled to the flexible bladder. The end fitting defining a bolt bore and a horizontal bore. When a vent bolt is operatively coupled to the bolt bore of the end fitting, the vent bolt and the horizontal bore define a pressure passageway that allows an interior of the bladder to become subjected to external pressure.

Abstract: A hybrid softening strip for controlling stresses in a joint at low temperatures includes a layer of sacrificial material that can be tailored to fit the softening strip in the joint after the softening strip has been bonded to a structure.

Abstract: A method of partially insulating an interior space of a pre-formed fluted core panel is disclosed herein. The fluted core panel includes a first facesheet, a second facesheet spaced apart from the first facesheet, and webs between the first facesheet and second facesheet. The interior space is defined between the first facesheet, the second facesheet, and adjacent webs. The method includes positioning a spacer in a first portion of the interior space, positioning a membrane between the spacer and a second portion of the interior space, and positioning insulation in the second portion of the interior space. Additionally, the method includes pressing the membrane against the spacer, curing the membrane, and removing the spacer from the first portion of the interior space.