Abstract: A method of controlling macroscopic properties of a metamaterial includes 3D printing a lattice structure comprising interconnected struts, where each strut comprises one or more printed filaments. Each printed filament comprises an active material or a passive material, and the active material has a modulus with a higher stimulus dependence than that of the passive material. The printed filaments comprising the active material are disposed at predetermined regions of the lattice structure. After 3D printing, the lattice structure is exposed to a stimulus, and the predetermined regions comprising the active material soften or stiffen. Thus, the macroscopic properties of the lattice structure may be controlled.

Abstract: A structural lattice includes a rectangular base defined by four periphery beams, and two non-diagonal beams that divide the rectangular base in four quadrants. The structural lattice further includes a diagonal reinforcement strut system overlaid on the rectangular base and having at least two intersecting sets of diagonal beams forming an open-and-closed cell architecture.

Abstract: An acoustic damper includes a low porosity layer section and a housing. The low porosity layer section is formed in a liner of a gas turbine combustor and has an arrangement of elongated generally S-shaped slots formed therein. The housing has a plurality of feed apertures. The housing is coupled to the low porosity layer section thereby defining a cavity such that air outside the housing is configured to flow through the apertures and through the elongated generally S-shaped slots in the low porosity layer section, thereby transforming acoustic energy into thermal energy and aiding in providing an acoustic dampening effect for the gas turbine combustor during operation thereof.

Abstract: A shoe comprises an upper portion, a sole, and a sheet of material. The upper portion is configured to receive a foot of a user. The sole is attached to the upper portion. The sheet of material is coupled to the sole. The material includes a substrate and one or more movable projections. The one or more movable projections are configured to extend from the substrate. The one or more movable projections are configured to move between a first orientation and a second orientation relative to the substrate, in response to the sole of the shoe moving between a generally flat configuration and a generally flexed configuration. The movable projections can have a triangular shape, a concave shape, a convex shape, a rectangular shape, or a barbed shape; and can be arranged in a one-direction pattern, a three-column pattern, a half pattern, a 16x2 pattern, or a checkerboard pattern.

Abstract: A structural lattice includes a rectangular base defined by four periphery beams, and two non-diagonal beams that divide the rectangular base in four quadrants. The structural lattice further includes a diagonal reinforcement strut system overlaid on the rectangular base and having at least two intersecting sets of diagonal beams forming an open-and-closed cell architecture.

Abstract: An aerodynamic device for enhancing lift and reducing drag on a body, comprising a plurality of raised members, each having a symmetric profile and including a central portion having an elongated profile, and first and second outer portions having elongated profiles and arranged substantially parallel to and on opposing sides of the central portion, wherein the plurality of raised members are situated adjacent one another to form a continuous structure on or defining at least a portion of a surface of the body and oriented such that the raised members are substantially aligned with a direction of localized flow on the body. An aerodynamic device for enhancing lift and reducing drag of a flying disc, wherein the plurality of raised members are situated adjacent one another to form a continuous structure and the raised members are oriented in a substantially circumferential direction on the surface of the flying disc.

Abstract: The present concepts include a zero-porosity structure having a plurality of structural elements arranged to provide a negative Poisson's ratio and, further, a new mechanism to generate negative Poisson's ratio is single material, zero-porosity structure.

Abstract: Void structures, systems and devices with void structures, and methods of fabricating void structures are disclosed. A void structure is disclosed with a repeating elongated-aperture pattern designed to provide negative Poisson's Ratio behavior under macroscopic stress and strain loading. The pattern can include horizontal and vertical elliptically shaped apertures that are arranged on horizontal and vertical lines in a way that the lines are equally spaced in both dimensions. The centers of each aperture is on a crossing point of two of the lines. The vertical and horizontal elliptically shaped apertures alternate on the vertical and horizontal lines such that any vertical aperture is surrounded by horizontal apertures along the lines (and vice versa), and the next vertical apertures are found on both diagonals. The voids can also act as cooling and/or damping holes and, due to their arrangement, also as stress reduction features.

Abstract: An acoustic damper includes a low porosity layer section and a housing. The low porosity layer section is formed in a liner of a gas turbine combustor and has an arrangement of elongated generally S-shaped slots formed therein. The housing has a plurality of feed apertures. The housing is coupled to the low porosity layer section thereby defining a cavity such that air outside the housing is configured to flow through the apertures and through the elongated generally S-shaped slots in the low porosity layer section, thereby transforming acoustic energy into thermal energy and aiding in providing an acoustic dampening effect for the gas turbine combustor during operation thereof.

Abstract: In at least some aspects, an auxetic structure includes a first sheet defining therein a plurality of a plurality of structural elements projecting from the first sheet, the plurality of structural elements being arranged to provide a negative Poisson's ratio, and a second sheet disposed adjacent the first sheet to define a first internal cavity between the first sheet and the second sheet. In yet other aspects, one or more additional sheets may be advantageously provided to provide a multi-layered structure having auxetic properties.

Abstract: Auxetic structures, low porosity auxetic sheets, systems and devices with auxetic structures, and methods of using and methods of making auxetic structures are disclosed. An auxetic structure is disclosed which includes an elastically rigid body with a plurality of apertures extending through the elastically rigid body and a plurality of protrusions projecting from the elastically rigid body. The apertures and protrusions are arranged in an engineered pattern, such as an array of rows and columns. The apertures are cooperatively configured with the protrusions to provide a predefined porosity while exhibiting stress reduction through negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions. In some embodiments, the protrusions, which are elliptical or semispherical dimples, are interposed in square or hexagonal patterns with the apertures, which are S-shaped through slots or circular boreholes.

Abstract: A kirigami structure including a thin flat sheet and a square-shaped array of perforations cut in the sheet. The array includes alternating rows and columns of adjacent orthogonal perforations interconnected via respective ligaments. The array forms a two-dimensional planar surface in a load-free state, and a three-dimensional kirigami surface in a tensile-load state in which a tensile load applied to the sheet causes out-of-plane buckling of the ligaments.

Abstract: In some aspects, an auxetic structure includes a first sheet and a second sheet, the first sheet defining therein a plurality of first openings in a first pattern, the plurality of first openings providing a first porosity and the second sheet defining therein a plurality of second openings in a second pattern to provide a second porosity. The second sheet is positioned to overlay the first sheet so that the plurality of second openings at least partially occlude the plurality of first openings to define a plurality of third openings in a third pattern, the plurality of third openings defining a third porosity less than that of the first porosity or the second porosity. The second sheet is connected to the first sheet by a plurality of distinct connection elements.

Abstract: Auxetic structures, effusion-cooling auxetic sheets, systems and devices with auxetic structures, and methods of using and methods of making auxetic structures are disclosed. An auxetic structure is disclosed which includes an elastically rigid body with opposing top and bottom surfaces. First and second pluralities of elongated apertures extend through the elastically rigid body from the top surface to the bottom surface. The first plurality of elongated apertures extends transversely with respect to the second plurality of elongated apertures. The first and/or second pluralities of elongated apertures are obliquely angled with the top surface of the elastically rigid body. The elongated apertures are cooperatively configured to provide a desired cooling performance while exhibiting stress reduction through negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions.

Abstract: In at least some aspects, an auxetic structure includes a first sheet defining therein a plurality of a plurality of structural elements projecting from the first sheet, the plurality of structural elements being arranged to provide a negative Poisson's ratio, and a second sheet disposed adjacent the first sheet to define a first internal cavity between the first sheet and the second sheet. In yet other aspects, one or more additional sheets may be advantageously provided to provide a multi-layered structure having auxetic properties.

Abstract: An aerodynamic device for enhancing lift and reducing drag on a body, comprising a plurality of raised members, each having a symmetric profile and including a central portion having an elongated profile, and first and second outer portions having elongated profiles and arranged substantially parallel to and on opposing sides of the central portion, wherein the plurality of raised members are situated adjacent one another to form a continuous structure on or defining at least a portion of a surface of the body and oriented such that the raised members are substantially aligned with a direction of localized flow on the body. An aerodynamic device for enhancing lift and reducing drag of a flying disc, wherein the plurality of raised members are situated adjacent one another to form a continuous structure and the raised members are oriented in a substantially circumferential direction on the surface of the flying disc.

Abstract: Auxetic structures, low porosity auxetic sheets, systems and devices with auxetic structures, and methods of using and methods of making auxetic structures are disclosed. An auxetic structure is disclosed which includes an elastically rigid body with a plurality of apertures extending through the elastically rigid body and a plurality of protrusions projecting from the elastically rigid body. The apertures and protrusions are arranged in an engineered pattern, such as an array of rows and columns. The apertures are cooperatively configured with the protrusions to provide a predefined porosity while exhibiting stress reduction through negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions. In some embodiments, the protrusions, which are elliptical or semispherical dimples, are interposed in square or hexagonal patterns with the apertures, which are S-shaped through slots or circular boreholes.

Abstract: The present concepts include a zero-porosity structure having a plurality of structural elements arranged to provide a negative Poisson's ratio and, further, a new mechanism to generate negative Poisson's ratio is single material, zero-porosity structure.

Abstract: Auxetic structures, effusion-cooling auxetic sheets, systems and devices with auxetic structures, and methods of using and methods of making auxetic structures are disclosed. An auxetic structure is disclosed which includes an elastically rigid body with opposing top and bottom surfaces. First and second pluralities of elongated apertures extend through the elastically rigid body from the top surface to the bottom surface. The first plurality of elongated apertures extends transversely with respect to the second plurality of elongated apertures. The first and/or second pluralities of elongated apertures have distorted shapes projected through the elastically rigid body at an oblique angle. The elongated apertures are cooperatively configured to provide a desired stress performance while exhibiting negative Poisson's Ratio (NPR) behavior under macroscopic planar loading conditions.

Abstract: In at least some aspects, there is provided a fluidic actuator including at least one fluidic actuator segment that includes an elastic tube, having a first initial length, and a braid, having a second initial length greater than the first initial length. The braid is disposed, in a buckled state, about the elastic tube and imparts an axial force to the elastic tube.