Abstract: A method of repairing a sandwich structure includes: removing a damaged portion of a core and a damaged portion of a first facesheet to form an open volume; filling the open volume with an ultraviolet-curable photomonomer; partially curing the ultraviolet-curable photomonomer to form a plurality of photopolymer waveguides by utilizing ultraviolet light; and arranging a replacement facesheet on the damaged portion of the first facesheet and over the photopolymer waveguides.

Abstract: A method of manufacturing a sandwich structure having an open cellular core and a fluid-tight seal surrounding the core includes coupling a mold to a first facesheet to define a reservoir. The method also includes irradiating a volume of photo-monomer in the reservoir with a series of vertical collimated light beams to form a cured, solid polymer border extending around a periphery of the first facesheet. The method also includes irradiating a remaining volume of photo-monomer in the reservoir with a series of collimated light beams to form an ordered three-dimensional polymer microstructure core defined by a plurality of interconnected polymer optical waveguides coupled to the first facesheet and surrounded by the cured, solid polymer border. The method further includes coupling a second facesheet to the ordered three-dimensional microstructure core and the cured, solid polymer border to form the sandwich structure.

Abstract: A composition for forming a microlattice structure includes a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a copolymer including a reaction product of a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a polymer including a reaction product of a photopolymerizable compound; and a flame retardant material.

Abstract: A method of repairing a sandwich structure includes: removing a damaged portion of a core and a damaged portion of a first facesheet to form an open volume; filling the open volume with an ultraviolet-curable photomonomer; partially curing the ultraviolet-curable photomonomer to form a plurality of photopolymer waveguides by utilizing ultraviolet light; and arranging a replacement facesheet on the damaged portion of the first facesheet and over the photopolymer waveguides.

Abstract: A three-dimensional lattice architecture with a thickness hierarchy includes a first surface and a second surface separated from each other with a distance therebetween defining a thickness of the three-dimensional lattice architecture; a plurality of angled struts extending along a plurality of directions between the first surface and the second surface; a plurality of nodes connecting the plurality of angled struts with one another forming a plurality of unit cells. At least a portion of the plurality of angled struts are internally terminated along the thickness direction of the lattice structure and providing a plurality of internal degrees of freedom towards the first or second surface of the lattice architecture.

Abstract: A method for repairing a composite structure. A damaged portion of a first facesheet of the structure is removed, forming a hole in the first facesheet. A damaged portion of the underlying core is removed to form a cavity in the sandwich. If the second facesheet is damaged, the damaged section is removed, and covered and sealed with a facesheet repair section. If the core material is an open-cell material, a dam is formed around the perimeter of the cavity, to act as a barrier between the cavity and the core material. The cavity is at least partially filled with a photomonomer resin, which then is illuminated through a mask with collimated light to form a truss structure in the cavity. Residual photomonomer resin is removed, and a facesheet repair section is bonded over the hole in the first facesheet.

Abstract: A method and/or system for forming a micro-truss structure in an essentially arbitrary shape. A mold that has a transparent portion, and having an interior volume in the desired shape, is filled with photomonomer resin. The material for the transparent portion of the mold is selected to be a material that is index-matched to the photomonomer resin. The filled mold, placed into a bath of transparent fluid index-matched to the transparent portion of the mold, and illuminated, from outside the fluid, through a photomask, with collimated light. The collimated light travels through the photomask forming beams of light that enter the transparent fluid, propagate into the mold, and form a micro-truss structure in the shape of the interior volume of the mold. The micro-truss structure may then be removed from the mold, or part or all of the mold may be left adhered to the micro-truss structure, forming covering face sheets.

Abstract: A low viscosity polysulfide sealant composition. The composition comprises a curable polysulfide polymer; a crosslinking agent; and a plurality of core-shell particles. The core-shell particles comprise: a core comprising a ferromagnetic material; and a shell comprising silica treated with an organic sulfur containing compound. The shell is capable of bonding with the polysulfide polymer.

Abstract: Methods of manufacturing a structure having at least one plated region and at least one unplated region. The method includes plating a metal on a polymer structure having a first region accepting the metal and a second region unreceptive to the metal plating. The first region may include fully-cured polymer optical waveguides and the second region may include partially-cured polymer optical waveguides. The first region may include a first polymer composition and the second region may include a second polymer composition different than the first polymer composition.

Abstract: Methods of manufacturing a structure having at least one plated region and at least one unplated region. The method includes plating a metal on a polymer structure having a first region accepting the metal and a second region unreceptive to the metal plating. The first region may include fully-cured polymer optical waveguides and the second region may include partially-cured polymer optical waveguides. The first region may include a first polymer composition and the second region may include a second polymer composition different than the first polymer composition.

Abstract: Architected materials with superior energy absorption properties when loaded in compression. In several embodiments such materials are formed from micro-truss structures composed of interpenetrating tubes in a volume between a first surface and a second surface. The stress-strain response of these structures, for compressive loads applied to the two surfaces, is tailored by arranging for some but not all of the tubes to extend to both surfaces, adjusting the number of layers of repeated unit cells in the structure, arranging for the nodes to be offset from alignment along lines normal to the surfaces, or including multiple interlocking micro-truss structures.

Abstract: A method of manufacturing a sandwich structure having an open cellular core and a fluid-tight seal surrounding the core includes coupling a mold to a first facesheet to define a reservoir. The method also includes irradiating a volume of photo-monomer in the reservoir with a series of vertical collimated light beams to form a cured, solid polymer border extending around a periphery of the first facesheet. The method also includes irradiating a remaining volume of photo-monomer in the reservoir with a series of collimated light beams to form an ordered three-dimensional polymer microstructure core defined by a plurality of interconnected polymer optical waveguides coupled to the first facesheet and surrounded by the cured, solid polymer border. The method further includes coupling a second facesheet to the ordered three-dimensional microstructure core and the cured, solid polymer border to form the sandwich structure.

Abstract: A system for forming a micro-truss structure including a reservoir having walls and a flat bottom configured to hold a volume of a liquid photomonomer configured to form a photopolymer when exposed to light, a partially transparent mask secured to, or being, the bottom of the reservoir, a release layer on the mask configured to resist adhesion by the photopolymer, and a blocker positioned a first distance below the mask. The system also includes a light source positioned below the blocker configured to produce collimated light suitable for causing conversion of the photomonomer into the photopolymer, and to which the blocker is opaque, and a first mirror, oblique to the blocker, configured to reflect the light from the light source around the blocker and through the mask and into the reservoir. The blocker is positioned to block a straight path of light from the light source to the mask.

Abstract: A composition for forming a microlattice structure includes a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a copolymer including a reaction product of a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a polymer including a reaction product of a photopolymerizable compound; and a flame retardant material.

Abstract: A multi-chemistry structure includes: a plurality of interconnected polymer struts arranged in a lattice; a first layer of the lattice including a first array of first unit cells; a second layer of the lattice including a second array of second unit cells; at least one region of the lattice being formed of a first polymer; and at least one region of the lattice being formed of a second polymer different from the first polymer.

Abstract: A three-dimensional lattice architecture with a thickness hierarchy includes a first surface and a second surface separated from each other with a distance therebetween defining a thickness of the three-dimensional lattice architecture; a plurality of angled struts extending along a plurality of directions between the first surface and the second surface; a plurality of nodes connecting the plurality of angled struts with one another forming a plurality of unit cells. At least a portion of the plurality of angled struts are internally terminated along the thickness direction of the lattice structure and providing a plurality of internal degrees of freedom towards the first or second surface of the lattice architecture.

Abstract: A three-dimensional lattice architecture with a thickness hierarchy includes a first surface and a second surface separated from each other with a distance therebetween defining a thickness of the three-dimensional lattice architecture; a plurality of angled struts extending along a plurality of directions between the first surface and the second surface; a plurality of nodes connecting the plurality of angled struts with one another forming a plurality of unit cells. At least a portion of the plurality of angled struts are internally terminated along the thickness direction of the lattice structure and providing a plurality of internal degrees of freedom towards the first or second surface of the lattice architecture.

Abstract: A composition for forming a microlattice structure includes a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a copolymer including a reaction product of a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a polymer including a reaction product of a photopolymerizable compound; and a flame retardant material.

Abstract: Branched hierarchical micro-truss structures may be incorporated into energy-absorbing structures to exhibit a tailored multi-stage buckling response to a range of different compressive loads. Branched hierarchical micro-truss structures may also be configured to function as vascular systems to deliver fluid for thermal load management or altering the aerodynamic properties of a vehicle or structure into which the branched hierarchical micro-truss structure is incorporated. The branched hierarchical micro-truss structure includes a first layer having a series of interconnected struts and a second layer having a series of struts branching outward from an end of each of the struts in the first layer.

Abstract: Methods of manufacturing a structure having at least one plated region and at least one unplated region. The method includes plating a metal on a polymer structure having a first region accepting the metal and a second region unreceptive to the metal plating. The first region may include fully-cured polymer optical waveguides and the second region may include partially-cured polymer optical waveguides. The first region may include a first polymer composition and the second region may include a second polymer composition different than the first polymer composition.