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: 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 system and method for forming microlattice structures of large thickness. In one embodiment, a photomonomer resin is secured in a mold having a transparent bottom, the interior surface of which is coated with a mold-release agent. A substrate is placed in contact with the top surface of the photomonomer resin. The photomonomer resin is illuminated from below by one or more sources of collimated light, through a photomask, causing polymer waveguides to form, extending up to the substrate, forming a microlattice structure connected with the substrate. After a layer of microlattice structure has formed, the substrate is raised using a translation-rotation system, additional photomonomer resin is added to the mold, and the photomonomer resin is again illuminated through the photomask, to form an additional layer of microlattice structure. The process is repeated multiple times to form a stacked microlattice structure.

Abstract: This disclosure enables direct 3D printing of preceramic polymers, which can be converted to fully dense ceramics. Some variations provide a preceramic resin formulation comprising a molecule with two or more C?X double bonds or C?X triple bonds, wherein X is selected from C, S, N, or O, and wherein the molecule further comprises at least one non-carbon atom selected from Si, B, Al, Ti, Zn, P, Ge, S, N, or O; a photoinitiator; a free-radical inhibitor; and a 3D-printing resolution agent. The disclosed preceramic resin formulations can be 3D-printed using stereolithography into objects with complex shape. The polymeric objects may be directly converted to fully dense ceramics with properties that approach the theoretical maximum strength of the base materials. Low-cost structures are obtained that are lightweight, strong, and stiff, but stable in the presence of a high-temperature oxidizing environment.

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 system and method for forming microlattice structures of large thickness. In one embodiment, a photomonomer resin is secured in a mold having a transparent bottom, the interior surface of which is coated with a mold-release agent. A substrate is placed in contact with the top surface of the photomonomer resin. The photomonomer resin is illuminated from below by one or more sources of collimated light, through a photomask, causing polymer waveguides to form, extending up to the substrate, forming a microlattice structure connected with the substrate. After a layer of microlattice structure has formed, the substrate is raised using a translation-rotation system, additional photomonomer resin is added to the mold, and the photomonomer resin is again illuminated through the photomask, to form an additional layer of microlattice structure. The process is repeated multiple times to form a stacked microlattice 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 three-dimensional microlattice structure includes a series of interconnected struts extending along at least three different directions, a series of intermediate nodes defined at intersections between the struts, and a basal plane structure extending laterally between and interconnecting at least two of the nodes. The basal plane structure may be configured to transversely and rotationally constrain the nodes to increase the overall compressive strength and stiffness of the microlattice structure. In one embodiment, the interconnected struts are arranged into an array of ordered unit cells.

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.