Abstract: Methods for vibration and acoustic abatement. The methods comprise providing a substrate with a composite layer deposited thereon, the substrate receiving a vibration energy sufficient to provide at least one bending wave therein, and converting at least a portion of the vibration energy sufficient to cause the at least one bending wave to at least one shear wave in at least a portion of the composite layer. The composite layer comprises an elastomeric polymer matrix comprising carbon nano tubes dispersed or distributed therein. Articles with the composite layer comprising carbon nano tubes disposed thereon are also disclosed and described.

Abstract: A composite structure and an associated exhaust washed structure are provided which may be formed of ceramic matrix composite (CMC) materials. A method of fabricating a composite structure which may include the CMC material is also provided. A composite structure may include a corrugated septum extending in a lengthwise direction. The composite structure may also include a flute within which the corrugated septum is disposed to form, for example, a partitioned flute assembly.

Abstract: A composite structure and an associated exhaust washed structure are provided which may be formed of ceramic matrix composite (CMC) materials. A method of fabricating a composite structure which may include the CMC material is also provided. A composite structure may include a corrugated septum extending in a lengthwise direction. The composite structure may also include a flute within which the corrugated septum is disposed to form, for example, a partitioned flute assembly.

Abstract: Methods for vibration and acoustic abatement. The methods comprise providing a substrate with a composite layer deposited thereon, the substrate receiving a vibration energy sufficient to provide at least one bending wave therein, and converting at least a portion of the vibration energy sufficient to cause the at least one bending wave to at least one shear wave in at least a portion of the composite layer. The composite layer comprises an elastomeric polymer matrix comprising carbon nano tubes dispersed or distributed therein. Articles with the composite layer comprising carbon nano tubes disposed thereon are also disclosed and described.

Abstract: A composite structure and an associated exhaust washed structure are provided which may be formed of ceramic matrix composite (CMC) materials. A method of fabricating a composite structure which may include the CMC material is also provided. A composite structure may include a corrugated septum extending in a lengthwise direction. The composite structure may also include a flute within which the corrugated septum is disposed to form, for example, a partitioned flute assembly.

Abstract: A composite structure and an associated exhaust washed structure are provided which may be formed of ceramic matrix composite (CMC) materials. A method of fabricating a composite structure which may include the CMC material is also provided. A composite structure may include a corrugated septum extending in a lengthwise direction. The composite structure may also include a flute within which the corrugated septum is disposed to form, for example, a partitioned flute assembly.

Abstract: A squeeze film damper reduces acoustic wave transmission by the damping and spring forces produced by squeezing a very thin layer of air trapped between two vibrating plates. The damping effect is most pronounced when the gap between vibrating plates is very small, e.g., of the order of micrometers, thus, the squeeze film dampers have two, very closely-spaced opposing plates, the top of which vibrates out-of-phase with respect to the lower plate, when the lower plate is attached to a vibrating surface. The relative motion of plates squeezes out the thin film of air trapped within the plates and adds substantial amount of passive damping over a wideband of frequency to the base vibrating structure thereby reducing vibrations and noise radiated by the structure. The out-of-phase displacement of the top plate, with respect to the bottom plate, tends to cancel acoustic energy imparted to the lower plate by a vibrating surface. Squeeze film dampers can be applied in arrays to a vibrating surface.

Abstract: A damped structural panel includes a panel having bending modes including demanding bending modes. The demanding bending modes have subsonic bending waves along at least one axis, and require damping treatment based on sound radiation properties of the panel. A viscoelastic material is applied within a limited area adjacent to the panel edges based on the demanding bending modes. The viscoelastic material damps sound radiation caused by bending waves during use of the structural panel, such as use as a body panel on an aircraft.

Abstract: A method and apparatus for reducing noise across a broadband frequency range transmitted by a vibrating panel by blocking or otherwise opposing increasing non-resonant modes of vibration in the panel. The method and apparatus includes mounting an array of sensors on a surface of the vibrating panel. The sensors generate an input signal representing the incident vibration in the panel. The input signal is sent to an adaptive controller which generates an output signal. The output signal is essentially equivalent to the input signal but opposing in phase. The output signal is then sent and distributed to an array of actuators which are also mounted to a surface of the vibrating panel. The output signal forces each of the vibrating actuators to vibrate the panel in opposition to the incident vibration in the panel and thus reduce the transmitted noise. Continual readings of the vibration in the panel allows the sensors to update the input signal and thus adjust the vibration of the actuators.

Abstract: The passive damping wedge for reducing sound radiation from reinforced structures excited by fluid flow over the outer surface of the structure. The damping wedge is generally attached at the trailing edge of the skin structure on the inner surface. The unique three-dimensional design of the damping wedge provides increased damping which absorbs vibrational energy in the structure. The wedge is made of viscoelastic material with a high damping capacity to maximize the ability to reflect vibrations within. The wedge generally has an elongated base which extends upwards from a flat lower surface. An upper surface tapers downwards from the base into a plurality of spaced apart front end members which extend away from the base. The wedge also has a plurality of pairs of sides, with each pair of sides tapering inwardly to generally define each of the front end members.