Abstract: The invention is directed to carbon fibers having high tensile strength and modulus of elasticity. The invention also provides a method and apparatus for making the carbon fibers. The method comprises advancing a precursor fiber through an oxidation oven wherein the fiber is subjected to controlled stretching in an oxidizing atmosphere in which tension loads are distributed amongst a plurality of passes through the oxidation oven, which permits higher cumulative stretches to be achieved. The method also includes subjecting the fiber to controlled stretching in two or more of the passes that is sufficient to cause the fiber to undergo one or more transitions in each of the two or more passes. The invention is also directed to an oxidation oven having a plurality of cooperating drive rolls in series that can be driven independently of each other so that the amount of stretch applied to the oven in each of the plurality of passes can be independently controlled.

Abstract: An assembly that includes a first part composed of a fibrous structure that includes fibers and a cured resin matrix. The fibrous structure has at least one surface and a layer that is located on the surface. The layer includes a discontinuous fiber composite that is composed of randomly oriented short fibers and a cured resin matrix wherein the layer has been machined to provide a machined surface. The assembly also includes a second part that is attached to the first part. The second part includes at least one surface that fits against the machined surface on the first part.

Abstract: The bandwidth or acoustical range of a nacelle or other type of acoustic structure is increased by acoustically coupling honeycomb cells together to form pairs of acoustic cells that have an effective acoustic or resonator length that is up to twice that of either acoustic cell taken alone.

Abstract: An acoustic structure that includes a septum having an acoustic opening which defines an open area that varies in response to changes in the velocity of noise-containing media passing through the acoustic opening. The septum includes a fixed portion and one or more movable flapper portions wherein the fixed portion and/or the flapper portion(s) include surfaces that define an acoustic opening through the septum. The acoustic opening has an open area which varies due to movement of the movable flapper(s) in response to changes in velocity of the noise-containing media that passes through the acoustic opening. The resulting septum has a relatively low non-linearity factor (NLF).

Abstract: A prepreg comprising a fibre reinforced curable resin, the curable resin being composed of 25 to 35 weight percent tetrafunctional epoxy resin based on the total weight of the curable resin; 18 to 28 weight percent difunctional epoxy resin; 4 to 18 weight percent polyether sulfone; 2 to 10 weight percent polyamide 12 particles; 2 to 10 weight percent polyamide 11 particles; 1 to 8 weight percent potato shaped graphite particles; and 17.4 to 27.4 weight percent of a curing agent for said curable resin.

Abstract: The invention is directed to carbon fibers having high tensile strength and modulus of elasticity. The invention also provides a method and apparatus for making the carbon fibers. The method comprises advancing a precursor fiber through an oxidation oven wherein the fiber is subjected to controlled stretching in an oxidizing atmosphere in which tension loads are distributed amongst a plurality of passes through the oxidation oven, which permits higher cumulative stretches to be achieved. The method also includes subjecting the fiber to controlled stretching in two or more of the passes that is sufficient to cause the fiber to undergo one or more transitions in each of the two or more passes. The invention is also directed to an oxidation oven having a plurality of cooperating drive rolls in series that can be driven independently of each other so that the amount of stretch applied to the oven in each of the plurality of passes can be independently controlled.

Abstract: Pre-impregnated composite material (prepreg) is provided that can be cured/molded to form composite parts having high damage tolerance and interlaminar fracture toughness. The matrix resin includes a thermoplastic particle component that includes a mixture of polyamide 12 particles and polyamide 11 particles.

Abstract: Composite pre-forms are molded at high pressure to form composite parts that can be used in place of metal-based high performance parts, such as the outlet guide vanes found in turbofan jet engines. The composite pre-forms include two different fiber orientations that are co-molded in a resin matrix at high pressures to provide composite outlet guide vanes and other high performance parts. Chambers within the composite part are optionally formed during molding of the pre-form at high pressures.

Abstract: The invention is directed to carbon fibers having high tensile strength and modulus of elasticity. The invention also provides a method and apparatus for making the carbon fibers. The method comprises advancing a precursor fiber through an oxidation oven wherein the fiber is subjected to controlled stretching in an oxidizing atmosphere in which tension loads are distributed amongst a plurality of passes through the oxidation oven, which permits higher cumulative stretches to be achieved. The method also includes subjecting the fiber to controlled stretching in two or more of the passes that is sufficient to cause the fiber to undergo one or more transitions in each of the two or more passes. The invention is also directed to an oxidation oven having a plurality of cooperating drive rolls in series that can be driven independently of each other so that the amount of stretch applied to the oven in each of the plurality of passes can be independently controlled.

Abstract: Thermally insulating septums are located internally within the cells of an acoustic honeycomb to regulate heat flow into the acoustic structure. The internally located insulating septums protect the honeycomb and acoustic septums located within the honeycomb cells from heat damage that might otherwise be caused by a heat source, such as the hot section of a jet engine. The internal thermal regulators are useful in combination with heat blankets or other thermal insulating structures to provide a reduction in size and/or weight of the insulating structure while still providing the same overall degree of thermal insulation for the acoustic honeycomb.

Abstract: A method for making an acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of flexible material that may be perforated before or after the material is inserted into the honeycomb. The flexible material is sufficiently flexible to allow folding into the shape of a septum cap. The flexible material is also sufficiently stiff to provide frictional engagement and locking of the septum cap to the honeycomb cell when the cap is inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Abstract: Thermally insulating septums are located internally within the cells of an acoustic honeycomb to regulate heat flow into the acoustic structure. The internally located insulating septums protect the honeycomb and acoustic septums located within the honeycomb cells from heat damage that might otherwise be caused by a heat source, such as the hot section of a jet engine. The internal thermal regulators are useful in combination with heat blankets or other thermal insulating structures to provide a reduction in size and/or weight of the insulating structure while still providing the same overall degree of thermal insulation for the acoustic honeycomb.

Abstract: The bandwidth or acoustical range of a nacelle or other type of acoustic structure is increased by acoustically coupling honeycomb cells together to form pairs of acoustic cells that have an effective acoustic or resonator length that is up to twice that of either acoustic cell taken alone.

Abstract: A honeycomb structure dial includes cells in which septums are located to provide acoustic dampening. The cells are formed by at least our walls wherein at least two of the walls are substantially parallel to each other. The septums include warp fibers and weft fibers that are substantially perpendicular to each other. The septums are oriented in the honeycomb cells such that the weft fibers and/or warp fibers are substantially perpendicular to the parallel walls.

Abstract: The solvent resistance of epoxy resins toughened with polyethersulfone is improved by using low molecular weight polyethersulfone. The resulting thermoplastic toughened epoxy resins are useful for making prepreg for aerospace applications.

Abstract: Pre-impregnated composite material (prepreg) is provided that can be cured/molded to form composite parts having high compression strength under hot and wet conditions, as well as, high damage tolerance and interlaminar fracture toughness. The matrix resin includes a thermoplastic particle component that includes polyamide particles which are composed of the polymeric condensation product of a methyl derivative of bis(4-aminocyclohexyl)methane and an aliphatic dicarboxylic acid.

Abstract: The bandwidth or acoustical range of a nacelle or other type of acoustic structure is increased by acoustically coupling honeycomb cells together to form pairs of acoustic cells that have an effective acoustic or resonator length that is up to twice that of either acoustic cell taken alone.

Abstract: Honeycomb sections are bonded together with seams made up of an adhesive that is carried by a linked-segment seam support. The seams are particularly useful for splicing together curved honeycomb sections that contain acoustic septum. The curved acoustic honeycomb sections are spliced or seamed together to form engine nacelles and other acoustic damping structures.

Abstract: A method for making an acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of flexible material that may be perforated before or after the material is inserted into the honeycomb. The flexible material is sufficiently flexible to allow folding into the shape of a septum cap. The flexible material is also sufficiently stiff to provide frictional engagement and locking of the septum cap to the honeycomb cell when the cap is inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Abstract: An acoustic structure that includes a septum having an acoustic opening which defines an open area that varies in response to changes in the velocity of noise-containing media passing through the acoustic opening. The septum includes a fixed portion and one or more movable flapper portions wherein the fixed portion and/or the flapper portion(s) include surfaces that define an acoustic opening through the septum. The acoustic opening has an open area which varies due to movement of the movable flapper(s) in response to changes in velocity of the noise-containing media that passes through the acoustic opening. The resulting septum has a relatively low non-linearity factor (NLF).