Abstract: Disclosed herein is a structure that comprises a tank including an outer cylindrical surface and a domed end. The structure also comprises a tank skirt positioned circumferentially around the tank. A wall of the tank and a wall of the tank skirt form two sides of a y-joint between the tank and the tank skirt. The y-joint includes a wedge structure positioned between the tank and the tank skirt. Additionally, a thickness of at least one of the wall of the tank or the wall of the tank skirt forming the y-joint tapers such that the thickness of the at least one of the wall of the tank or the wall of the tank skirt that tapers has a greater thickness at the y-joint than away from the y-joint.

Abstract: Disclosed herein is a structure that comprises a tank including an outer cylindrical surface and a domed end. The structure also comprises a tank skirt positioned circumferentially around the tank. A wall of the tank and a wall of the tank skirt form two sides of a y-joint between the tank and the tank skirt. The y-joint includes a wedge structure positioned between the tank and the tank skirt. Additionally, a thickness of at least one of the wall of the tank or the wall of the tank skirt forming the y-joint tapers such that the thickness of the at least one of the wall of the tank or the wall of the tank skirt that tapers has a greater thickness at the y-joint than away from the y-joint.

Abstract: Disclosed herein is a structure that comprises a tank including an outer cylindrical surface and a domed end. The structure also comprises a tank skirt positioned circumferentially around the tank. A wall of the tank and a wall of the tank skirt form two sides of a y-joint between the tank and the tank skirt. The y-joint includes a wedge structure positioned between the tank and the tank skirt. Additionally, a thickness of at least one of the wall of the tank or the wall of the tank skirt forming the y-joint tapers such that the thickness of the at least one of the wall of the tank or the wall of the tank skirt that tapers has a greater thickness at the y-joint than away from the y-joint.

Abstract: Disclosed herein is a structure that comprises a tank including an outer cylindrical surface and a domed end. The structure also comprises a tank skirt positioned circumferentially around the tank. A wall of the tank and a wall of the tank skirt form two sides of a y-joint between the tank and the tank skirt. The y-joint includes a wedge structure positioned between the tank and the tank skirt. Additionally, a thickness of at least one of the wall of the tank or the wall of the tank skirt forming the y-joint tapers such that the thickness of the at least one of the wall of the tank or the wall of the tank skirt that tapers has a greater thickness at the y-joint than away from the y-joint.

Abstract: Methods and systems for restricting movement in a flow mixer including a plurality of lobes that each includes a trough, using a stiffener mechanism, are provided. The stiffener mechanism includes a first end portion configured to be coupled to a first lobe of the plurality of lobes and a second end portion configured to be coupled to a second lobe of the plurality of lobes. The stiffener mechanism also includes a body portion coupled between the first end portion and the second end portion such that the body portion is configured to restrict movement of the first and second lobes.

Abstract: A hybrid sandwich ceramic matrix composite (CMC) may comprise a first facesheet, a second facesheet, and a core between and bonded to both of the first facesheet and the second facesheet. The first facesheet and the second facesheet may each include filaments in a ceramic matrix. The hybrid sandwich CMC may be configured for exposure to a thermal gradient in which the first facesheet is exposed to a higher temperature environment than the second facesheet. The first facesheet and the second facesheet may have at least closely matching coefficients of thermal expansion, and the first facesheet may have a higher compressive strength than the second facesheet.

Abstract: A CMC sandwich used to fabricate CMC structures includes facesheets bonded to a core reinforced with a ceramic truss comprising an array of CMC pins. The binder matrix in the ends of the pins is removed, leaving exposed, flexible ceramic fibers. The exposed ceramic fibers are bent so as to extend parallel to the facesheets, and are bonded to one or more plies of the facesheets. The binder matrix in the ends of the ceramic pins may be removed by mechanical or chemical processes.

Abstract: Methods and systems for restricting movement in a flow mixer including a plurality of lobes that each includes a trough, using a stiffener mechanism, are provided. The stiffener mechanism includes a first end portion configured to be coupled to a first lobe of the plurality of lobes and a second end portion configured to be coupled to a second lobe of the plurality of lobes. The stiffener mechanism also includes a body portion coupled between the first end portion and the second end portion such that the body portion is configured to restrict movement of the first and second lobes.

Abstract: A hybrid sandwich ceramic matrix composite (CMC) may comprise a first facesheet, a second facesheet, and a core between and bonded to both of the first facesheet and the second facesheet. The first facesheet and the second facesheet may each include filaments in a ceramic matrix. The hybrid sandwich CMC may be configured for exposure to a thermal gradient in which the first facesheet is exposed to a higher temperature environment than the second facesheet. The first facesheet and the second facesheet may have at least closely matching coefficients of thermal expansion, and the first facesheet may have a higher compressive strength than the second facesheet.

Abstract: A test method and corresponding fixture design are provided which enable loading a circular test coupon (made, e.g., of ceramic matrix composite material) to failure under biaxial loading conditions while recording strain and temperature. Biaxial loading requires approximately equal loads to be applied in two directions concurrently. The disclosed method uses liquid coolant (e.g., liquid nitrogen) to cool a ring made of metal alloy (e.g., aluminum alloy) that is disposed radially outward from and surrounds the outer edge of the test coupon. The cooled metal alloy ring contracts and compresses the test coupon until failure occurs.

Abstract: A test method and corresponding fixture design are provided which enable loading a circular test coupon (made, e.g., of ceramic matrix composite material) to failure under biaxial loading conditions while recording strain and temperature. Biaxial loading requires approximately equal loads to be applied in two directions concurrently. The disclosed method uses liquid coolant (e.g., liquid nitrogen) to cool a ring made of metal alloy (e.g., aluminum alloy) that is disposed radially outward from and surrounds the outer edge of the test coupon. The cooled metal alloy ring contracts and compresses the test coupon until failure occurs.

Abstract: A thermal coupling includes a first structure having a first coefficient of thermal expansion; a second structure having a second coefficient of thermal expansion lower than the first coefficient of thermal expansion; a plurality of thermal expansion fingers provided in the first structure; a plurality of thermal expansion flanges extending from the plurality of thermal expansion fingers, respectively; and a flange extending from the second structure and attached to the plurality of thermal expansion flanges.

Abstract: A scalloped flexure ring. An illustrative embodiment of the flexure ring includes a ring body having a first ring body edge and a generally scalloped second ring body edge and a plurality of spaced-apart ring fingers provided in the second ring body edge.

Abstract: A laminated ceramic matrix composite structure is strengthened with one or more layers of a metal reinforcement. The metal reinforcement is selected to provide optimal strength and thermal compatibility with the ceramic matrix composite. The metal reinforcement includes an outer oxidized layer that bonds to the ceramic matrix composite. It may also include a barrier layer on the surface of the metal that helps prevent further oxidation. The structure is formed using standard composite prepreg layup techniques.

Abstract: A thermal coupling includes an attachment frame; a plurality of substantially straight or planar frame ribs extending from said attachment frame, said attachment frame comprising an annular frame ring, said plurality of frame ribs generally parallel to said frame ring; a plurality of fastener rings provided on said plurality of frame ribs, respectively, said fastener rings extending substantially perpendicular to said frame ribs; and plurality of fastener ring openings provided in said plurality of fastener rings, respectively.

Abstract: A thermal coupling includes a first structure having a first coefficient of thermal expansion; a second structure having a second coefficient of thermal expansion lower than the first coefficient of thermal expansion; a plurality of thermal expansion fingers provided in the first structure; a plurality of thermal expansion flanges extending from the plurality of thermal expansion fingers, respectively; and a flange extending from the second structure and attached to the plurality of thermal expansion flanges.

Abstract: A laminated ceramic matrix composite structure is strengthened with one or more layers of a metal reinforcement. The metal reinforcement is selected to provide optimal strength and thermal compatibility with the ceramic matrix composite. The metal reinforcement includes an outer oxidized layer that bonds to the ceramic matrix composite. It may also include a barrier layer on the surface of the metal that helps prevent further oxidation. The structure is formed using standard composite prepreg layup techniques.

Abstract: A thermal coupling includes a first structure having a first coefficient of thermal expansion; a second structure having a second coefficient of thermal expansion lower than the first coefficient of thermal expansion; a plurality of thermal expansion fingers provided in the first structure; a plurality of thermal expansion flanges extending from the plurality of thermal expansion fingers, respectively; and a flange extending from the second structure and attached to the plurality of thermal expansion flanges.

Abstract: A scalloped flexure ring. An illustrative embodiment of the flexure ring includes a ring body having a first ring body edge and a generally scalloped second ring body edge and a plurality of spaced-apart ring fingers provided in the second ring body edge.

Abstract: A CMC sandwich used to fabricate CMC structures includes facesheets bonded to a core reinforced with a ceramic truss comprising an array of CMC pins. The binder matrix in the ends of the pins is removed, leaving exposed, flexible ceramic fibers. The exposed ceramic fibers are bent so as to extend parallel to the facesheets, and are bonded to one or more plies of the facesheets. The binder matrix in the ends of the ceramic pins may be removed by mechanical or chemical processes.