Patent Description:
At least some known assemblies (e.g., in the aircraft industry) include components that vibrate during operation. For example, at least some known aircraft include an external cabin air compressor inlet that generates high vibration levels, which often results in noise levels that exceed a desired threshold. To facilitate controlling and/or reducing a vibration and/or noise level of the external cabin air compressor inlet, at least some known aircraft include at least one vibration and/or noise-control component. However, at least some known vibration and/or noise-control components are bulky and/or inefficient and, thus, increase a weight of the aircraft to a level that may exceed a desired threshold, thereby reducing a performance level of the aircraft. Moreover, at least some known vibration and/or noise-control components are stiff and/or are not configured to withstand at least some vibration frequencies and/or temperature ranges of the aircraft.

Patent document <CIT>, according to its abstract, states that systems and methods for reducing noise in aircraft fuselages and other structures are described. A noise reduction system includes an auxetic core, a damping layer, and a constraining layer. The auxetic core is supported by a structural member, and the damping layer is sandwiched between the auxetic core and the constraining layer. A method for manufacturing a structural assembly includes forming a stiffener by positioning a first ply of composite material against a first tool surface, positioning damping material against the first ply, and positioning a second ply of composite material against the damping material to sandwich the damping material between the first and second plies. The method can further include forming a skin by positioning a third ply of composite material against a second tool surface offset from the first tool surface, and attaching the stiffener to the skin by co-curing the first, second and third plies of composite material.

<CIT> also states, in paragraph [<NUM>] thereof, that two constrained layer damping systems are configured in accordance with the prior art. The first damping system is attached to a longitudinal stiffener which in turn is attached to a fuselage skin. The damping system includes a constraining layer which is bonded to the stiffener by an adhesive layer. The constraining layer is typically aluminum, and the adhesive layer is typically a viscoelastic adhesive, such as one of the Scotch Damp Viscoelastic Adhesives products provided by the <NUM>(TM) Company under the ISD-<NUM>, ISD-<NUM>, or ISD-<NUM> part numbers. The second prior art damping system includes an angled constraining layer attached to a stiffener by means of an adhesive layer. With the exception of the angle, the constraining layer and the adhesive layer can be similar in structure and function to their counterparts in the first damping system.

Patent document <CIT>, according to its abstract, states that a composite stiffness layer is provided in segments and the orientation of the reinforcing fibers in adjacent segments is dissimilar. A damping layer may be integral with a stiffness layer, adhered to a stiffness layer, or sandwiched between stiffness layers. Multiple layer composite structures may be formed as tubes, plates, beams or other forms with improved damping proportions.

Patent document <CIT>, according to its abstract, states an inlet apparatus and method for use with a cabin air compressor on a high speed, airborne mobile platform. The apparatus includes a Pitot inlet of a desired shape that is supported outside an exterior surface of a fuselage of the aircraft by a diverter structure. The diverter structure diverts a low energy portion of a boundary layer so that the low energy portion does not enter the Pitot inlet. The Pitot inlet receives the higher energy portion of the boundary layer and channels a ram airflow to an inlet of a cabin air compressor. The apparatus provides a recovery factor of at least about <NUM> at a cabin air compressor (CAC) inlet face, which keeps the electric power required to drive the CAC within available power limits, while minimizing the drag of the inlet apparatus.

The present disclosure provides an aircraft cabin air compressor (CAC) inlet, according to claim <NUM> and a method for making an aircraft cabin air compressor (CAC) inlet according to claim <NUM>.

The features, functions, and advantages described herein may be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments, further details of which may be seen with reference to the following description and drawings.

Although specific features of various embodiments may be shown in some drawings and not in others, such illustrations are for convenience only. Any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

The subject matter described herein relates generally to damping mechanisms and, more particularly, to methods and systems for use in damping a panel or component, such as a cabin air compressor inlet. In one embodiment, a panel includes a structural substrate and a damping element including a viscoelastic material (VEM) layer coupleable to the structural substrate of the aircraft, and a constraining layer coupled to the VEM layer. The VEM layer is configured to dampen a vibration and/or noise of the structural substrate. The constraining layer is configured to apply a shear force to the VEM layer.

The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to determining a structural parameter of a damping mechanism to facilitate reducing a vibration and/or noise level associated with a structural substrate coupled to the damping mechanism.

An element or step recited in the singular and preceded with the word "a" or "an" should be understood as not excluding plural elements or steps unless such exclusion is explicitly recited. Moreover, references to "one embodiment" of the present invention and/or the "exemplary embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

The following illustrative embodiments are provided, which are not to be confused with the appended claims which determine the scope of protection:
In a first illustrative example, a method for making a panel (<NUM>) for use in an aircraft (<NUM>) is provided, said method comprising:.

Optionally, in the method of the first illustrative example, coupling a VEM layer (<NUM>) to a structural substrate (<NUM>) comprises coupling the VEM layer to the structural substrate having at least one surface that is contoured.

Optionally, in the method of the first illustrative example, coupling a VEM layer (<NUM>) to a structural substrate (<NUM>) further comprises coupling the VEM layer to the structural substrate, such that at least a portion of the structural substrate is exposed.

Optionally, the method of the first illustrative example further comprises substantially concurrently curing the structural substrate (<NUM>) and the VEM layer (<NUM>).

Optionally, the method of the first illustrative example further comprises substantially concurrently curing the constraining layer (<NUM>) and the VEM layer (<NUM>).

Optionally, the method of the first illustrative example further comprises bonding the VEM layer (<NUM>) to the structural substrate (<NUM>), when not substantially concurrently curing the structural substrate (<NUM>) and the VEM layer (<NUM>).

Optionally, the method of the first illustrative example further comprises bonding the constraining layer (<NUM>) to the VEM layer (<NUM>), when not substantially concurrently curing the constraining layer (<NUM>) and the VEM layer (<NUM>).

In a second illustrative example, a damping element (<NUM>) for use in an aircraft (<NUM>) is provided, the damping element comprising:.

Optionally, in the damping element of the second illustrative example, the first VEM layer (<NUM>) is coupleable to the first surface of the structural substrate (<NUM>), such that at least a portion of the structural substrate is exposed.

Optionally, the damping element of the second illustrative example further comprises a second VEM layer (<NUM>) coupled to the first constraining layer (<NUM>), the second VEM layer configured to further dampen the vibration of the structural substrate (<NUM>), and preferably further comprising:
a second constraining layer (<NUM>) coupled to the second VEM layer (<NUM>), the second constraining layer configured to apply a shear force to the second VEM layer.

Optionally, the damping element of the second illustrative example further comprises a second VEM layer (<NUM>) coupleable to a second surface of the structural substrate (<NUM>), the second VEM layer configured to further dampen the vibration of the structural substrate (<NUM>), and preferably further comprising:
a second constraining layer (<NUM>) coupled to the second VEM layer (<NUM>), the second constraining layer configured to apply a shear force to the second VEM layer.

In a third illustrative example, a panel (<NUM>) for use in an aircraft (<NUM>) is provided, the panel comprising:.

Optionally, in the panel of the third illustrative example, the structural substrate (<NUM>) has at least one surface that is contoured.

<FIG> is a plan view of an exemplary aircraft <NUM>. In the exemplary embodiment, aircraft <NUM> includes a body <NUM> that includes a fuselage <NUM>. Fuselage <NUM> includes a cabin defined therein. In the exemplary embodiment, body <NUM> includes a pair of wings <NUM> extending from fuselage <NUM>. In the exemplary embodiment, at least one engine <NUM> is coupled to each wing <NUM> to provide thrust to aircraft <NUM>.

<FIG> is a perspective view of an exemplary cabin air compressor (CAC) inlet <NUM> that at least partially defines an outer surface <NUM> of aircraft <NUM>. CAC inlet <NUM> is configured to channel air from an external source for use in the cabin of aircraft <NUM>. In the exemplary embodiment, CAC inlet <NUM> includes at least one surface <NUM> that has a complex configuration (i.e., surface <NUM> is not planar). For example, in one implementation, surface <NUM> is contoured to facilitate reducing a drag associated with CAC inlet <NUM>. Alternatively, CAC inlet <NUM> may have any shape and/or configuration that enables CAC inlet <NUM> to function as described herein.

In the exemplary embodiment, CAC inlet <NUM> is fabricated from at least one material that enables CAC inlet <NUM> to substantially maintain its physical shape and/or configuration in a plurality of operating environments. In one implementation, CAC inlet <NUM> includes a composite layer and/or is fabricated from a composite material. Alternatively, CAC inlet <NUM> may include and/or be fabricated from any material, such as metal, polymer, fiberglass, and/or carbon fiber.

<FIG> is a cross-sectional view of an exemplary panel <NUM> that may be used to form at least a portion of aircraft <NUM>, such as CAC inlet <NUM>. The panel <NUM> forms at least a portion of a shell of CAC inlet <NUM>.

The panel <NUM> includes a structural substrate <NUM> and one or more damping elements <NUM> that are coupled and/or coupleable to structural substrate <NUM>. In one implementation, damping element <NUM> is laid up on an interior surface of CAC inlet <NUM>. Alternatively, damping element <NUM> may be laid up on any surface that enables damping element <NUM> to function as described herein. In the exemplary embodiment, a first damping element <NUM> may be positioned or laid up on a first surface of structural substrate <NUM> to dampen a vibration and/or noise of structural substrate <NUM>, and a second damping element <NUM> may be positioned or laid up on the first damping element <NUM> to further dampen the vibration and/or noise of structural substrate <NUM> (i.e., damping elements <NUM> are laid up in a plurality of layers). Additionally or alternatively, a first damping element <NUM> may be positioned or laid up on a first surface of structural substrate <NUM> to dampen a vibration and/or noise of structural substrate <NUM>, and a second damping element <NUM> may be positioned or laid up on a second surface of structural substrate <NUM> to further dampen the vibration and/or noise of structural substrate <NUM>.

The damping element <NUM> includes a viscoelastic material (VEM) layer <NUM> and a constraining layer <NUM> that are laid up on structural substrate <NUM>. Accordingly, in the exemplary embodiment implementation, a first VEM layer <NUM> is positioned or laid up on a first surface of structural substrate <NUM> to absorb vibrational energy and/or reduce a vibration and/or noise level transmitted by structural substrate <NUM>, and a first constraining layer <NUM> is positioned or laid up on the first VEM layer <NUM> to apply a shear force to the first VEM layer <NUM> and/or shield the first VEM layer <NUM> from environmental conditions. In one implementation, a second VEM layer <NUM> is positioned or laid up on a second surface of structural substrate <NUM> to further absorb vibrational energy and/or reduce a vibration and/or noise level transmitted by structural substrate <NUM>, and a second constraining layer <NUM> is positioned or laid up on the second VEM layer <NUM> to apply a shear force to the second VEM layer <NUM> and/or shield the second VEM layer <NUM> from environmental conditions. The second surface of structural substrate <NUM> may be on the same side (e.g., on an interior surface of CAC inlet <NUM>) and/or adjacent to the first surface of structural substrate <NUM> and/or on an opposite side (e.g., on an exterior surface of CAC inlet <NUM>) to the first surface of structural substrate <NUM>. Additionally or alternatively, another VEM layer <NUM> is positioned or laid up on the first and/or second VEM layer <NUM> to further absorb vibrational energy and/or reduce a vibration and/or noise level transmitted by structural substrate <NUM>, and another constraining layer <NUM> is positioned or laid up on the another VEM layer <NUM> to apply a shear force to VEM layer <NUM> and/or shield the another VEM layer <NUM> from environmental conditions.

In the exemplary embodiment, VEM layer <NUM> is coupled and/or coupleable to structural substrate <NUM>, such that VEM layer <NUM> encapsulates at least a portion of structural substrate <NUM>. In the exemplary embodiment, VEM layer <NUM> includes a urethane layer and/or is fabricated from a urethane material. In one implementation, VEM layer <NUM> includes a polyalcohol material, a hardening material, a filler material, a catalyst material, and a viscosity modifying material. Alternatively, VEM layer <NUM> may include and/or be fabricated from any material that enables damping element <NUM> to function as described herein. For example, in one implementation, at least one material used to fabricate VEM layer <NUM> is selected and/or determined based on an operating parameter, such as a temperature range, a vibration frequency range, and/or a physical configuration associated with structural substrate <NUM>.

The constraining layer <NUM> is coupled and/or coupleable to VEM layer <NUM>, such that constraining layer <NUM> encapsulates VEM layer <NUM>. In the exemplary embodiment, constraining layer <NUM> includes a fiberglass layer and/or is fabricated from a fiberglass material. Alternatively, constraining layer <NUM> may include and/or be fabricated from any material that enables damping element <NUM> to function as described herein. For example, in one implementation, at least one material used to fabricate constraining layer <NUM> is selected and/or determined based on an operating parameter, such as a temperature range, a vibration frequency range, and/or a physical configuration associated with structural substrate <NUM> and/or VEM layer <NUM>.

In the exemplary embodiment, damping element <NUM> is integrated into structural substrate <NUM>. More specifically, in the exemplary embodiment, VEM layer <NUM> is applied directly to structural substrate <NUM> and backed by constraining layer <NUM>. Any combination of structural substrate <NUM>, VEM layer <NUM>, and/or constraining layer <NUM> may be concurrently cured. In a first implementation, structural substrate <NUM>, VEM layer <NUM>, and constraining layer <NUM> are laid up and concurrently cured. In a second implementation, VEM layer <NUM> and constraining layer <NUM> are laid up and cured independent of structural substrate <NUM>, and a lower surface <NUM> of VEM layer <NUM> is bonded to an upper surface <NUM> structural substrate <NUM>. In a third implementation, constraining layer <NUM> is laid up and cured independent of structural substrate <NUM> and VEM layer <NUM>, and a lower surface <NUM> of constraining layer <NUM> is bonded to an upper surface <NUM> of VEM layer <NUM>. Alternatively, structural substrate <NUM>, VEM layer <NUM>, and constraining layer <NUM> may be cured independently and bonded together.

In the exemplary embodiment, damping element <NUM> has at least one structural parameter including a modulus of elasticity, a damping element thickness <NUM> between lower surface <NUM> of VEM layer <NUM> and an upper surface <NUM> of constraining layer <NUM>, a VEM layer thickness <NUM> between lower surface <NUM> of VEM layer <NUM> and upper surface <NUM> of VEM layer <NUM>, a constraining layer thickness <NUM> between lower surface <NUM> of constraining layer <NUM> and upper surface <NUM> of constraining layer <NUM>, and/or a distribution of damping element <NUM> about structural substrate <NUM>. The modulus of elasticity is associated with a material used to fabricate at least a portion of damping element <NUM> and is representative of a tendency of damping element <NUM> to be elastically deformed when a force is applied to damping element <NUM>.

<FIG> is a schematic illustration of various distributions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of damping element <NUM> about CAC inlet <NUM>. In at least some embodiments, damping element <NUM> is laid up and/or coupled to structural substrate <NUM> in accordance with a predetermined and/or desired distribution of damping element <NUM> about structural substrate <NUM>, such that a first surface or portion <NUM> of structural substrate <NUM> is at least partially covered by VEM layer <NUM>, and a second surface or portion <NUM> of structural substrate <NUM> is not covered by VEM layer <NUM> (i.e., second portion <NUM> is exposed). For example, distribution <NUM> is associated with a substantially-full-coverage configuration of damping element <NUM> about CAC inlet <NUM>, distribution <NUM> is associated with a predetermined-edge-clearance configuration of damping element <NUM> about CAC inlet <NUM>, distribution <NUM> is associated with a no-back configuration of damping element <NUM> about CAC inlet <NUM>, distribution <NUM> is associated with a cut-sides configuration of damping element <NUM> about CAC inlet <NUM>, distribution <NUM> is associated with a no-triangles configuration of damping element <NUM> about CAC inlet <NUM>, and distribution <NUM> is associated with another cut-sides configuration of damping element <NUM> about CAC inlet <NUM>. In at least some implementations, a distribution of damping element <NUM> and/or VEM layer <NUM> is determined based on a design specification of structural substrate <NUM> and/or aircraft <NUM>, such as a position and/or orientation of fasteners and/or openings. A distribution, such as distribution <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, can be selected based on noise, vibration, weight, and/or other considerations.

To manufacture panel <NUM>, in the exemplary embodiment, VEM layer <NUM> is coupled to structural substrate <NUM>. In one implementation, VEM layer <NUM> is laid up when pliable, such that VEM layer <NUM> is easily contoured and/or shaped over structural substrate <NUM>. In the exemplary embodiment, constraining layer <NUM> is coupled to VEM layer <NUM>. In one implementation, constraining layer <NUM> is laid up when pliable, such that constraining layer <NUM> is easily contoured and/or shaped over VEM layer <NUM>.

<FIG> is a flowchart of an example method <NUM> for determining a desired parameter associated with the one or more damping elements <NUM>. During operation, in the exemplary embodiment, at least one first structural parameter associated with one or more damping elements <NUM>, VEM layers <NUM> and/or constraining layers <NUM> is defined <NUM>. Structural parameters include, for example, a modulus of elasticity of damping element <NUM>, VEM layer <NUM> and/or constraining layer <NUM>; a thickness of damping element <NUM>, VEM layer <NUM> and/or constraining layer <NUM>; a composition of damping element <NUM> (e.g., an alcohol content and/or a filler content of a material used to fabricate VEM layer <NUM>), VEM layer <NUM> and/or constraining layer <NUM>; and/or a distribution of damping element <NUM>, VEM layer <NUM> and/or constraining layer <NUM> about structural substrate <NUM>. In one implementation, a plurality of the modulus of elasticity, the thickness, the composition, and/or the distribution are defined <NUM>. For example, in one embodiment, the modulus of elasticity of VEM layer <NUM> (e.g., urethane) is between approximately <NUM> pounds per square inch (psi) (approximately <NUM> kilopascal (kPa)) and approximately <NUM>,<NUM> psi (approximately <NUM>,<NUM> kPa); VEM layer thickness <NUM> is between approximately <NUM> inch (in. ) (approximately <NUM> millimeters (mm)) and approximately <NUM> in. (approximately <NUM>); the modulus of elasticity of constraining layer <NUM> is between approximately <NUM>,<NUM> psi (approximately <NUM>,<NUM>,<NUM> kPa) and <NUM>,<NUM>,<NUM> psi (approximately <NUM>,<NUM>,<NUM> kPa), and constraining layer thickness <NUM> is between approximately <NUM> in. (approximately <NUM>) and approximately <NUM> inch (approximately <NUM>). Alternatively, any structural parameters may be defined that enables method <NUM> to function as described herein.

In the exemplary embodiment, at least one first operating parameter associated with structural substrate <NUM> and/or damping element <NUM> is defined <NUM>. Operating parameters include, for example, an operating temperature, an operating frequency, and/or a physical configuration (e.g., shape, size, weight). In one implementation, a plurality of the operating temperature, the operating frequency, and/or the physical configuration are defined <NUM>. For example, in one embodiment, an operating temperature range is between approximately -<NUM> °F (approximately -<NUM>) and approximately <NUM> °F (approximately <NUM>), and an operating frequency range is between approximately <NUM> Hertz (Hz) and approximately <NUM>,<NUM>. Alternatively, any operating parameters may be defined that enables method <NUM> to function as described herein.

Evaluating a strain energy distribution and/or a ratio of shear modulus to thickness, for example, of structural substrate <NUM> and/or damping element <NUM> may enable a user to determine where damping will be effective. Modulus of elasticity, thickness, and/or distribution (e.g., distribution <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and/or <NUM>) may be tailored to satisfy vibration, noise, and/or weight requirements. For example, a finite element analysis for a predetermined and/or defined operating parameter may be used to identify and/or determine a desired modulus of elasticity, a desired thickness, and/or a desired distribution based on a strain energy distribution and/or a ratio of shear modulus to thickness. In at least some implementations, a desired distribution (e.g., distribution <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and/or <NUM>) may be determined, such that a desired thickness of damping element <NUM> is substantially zero in at least one region.

In the exemplary embodiment, a first performance of structural substrate <NUM> and/or damping element <NUM> is simulated <NUM> to generate a first performance data set. The first performance data set is associated with the first structural parameter and the first operating parameter. In the exemplary embodiment, a finite element model associated with structural substrate <NUM> to be damped and/or damping element <NUM> is generated based at least on the first structural parameter and the first operating parameter, and a finite element analysis is performed using the finite element model. For example, in one implementation, a finite element model of a nominal VEM layer <NUM> and a nominal constraining layer <NUM> are added to at least one surface of structural substrate <NUM>. Alternatively, an evaluation setting may be defined using any method and/or process that enable the methods and systems to function as described herein.

In the exemplary embodiment, the first performance data set (e.g., a vibration and/or noise level) is compared to a predetermined threshold (e.g., a predetermined vibration and/or noise level) to determine <NUM> whether the first performance data set satisfies the predetermined threshold. If it is determined <NUM> that the first performance data set satisfies the predetermined threshold, then the first structural parameter (e.g., the modulus of elasticity, the thickness, and/or the distribution) is identified as a desired structural parameter for use in reducing a vibration and/or noise level associated with structural substrate <NUM>.

The predetermined threshold is a value (or set of values) that represent a boundary (or set of boundaries) that distinguish a desired result from an undesired result. For example, in one implementation, the first performance data set includes at least one value associated with a vibration and/or noise level associated with structural substrate <NUM> having a first structural parameter. In such an implementation, the vibration and/or noise level associated with structural substrate <NUM> having the first structural parameter is compared to a boundary between a desired vibration and/or noise level and an undesired vibration and/or noise level. If the vibration and/or noise level associated with structural substrate <NUM> is determined to be a desired vibration and/or noise level, then the first structural parameter is determined and/or identified to be a desired structural parameter.

If it is determined that the first performance data does not satisfy the predetermined threshold, then the first structural parameter and/or the first operating parameter is adjusted and/or a second structural parameter and/or a second operating parameter is defined <NUM>, <NUM> and the finite element model is modified in accordance with the adjusted and/or newly defined parameter. For example, in one implementation, a material property of a damping material is adjusted by determining an alcohol content and/or a filler content of at least one material used to fabricate VEM layer <NUM>. In the exemplary embodiment, a second performance of structural substrate <NUM> and/or damping element <NUM> is simulated <NUM> to generate a second performance data set, which is compared to the predetermined threshold. In the exemplary embodiment, method <NUM> is iteratively repeated until at least one structural parameter that satisfies the predetermined threshold is identified.

In another implementation, the method includes calculating a respective loss factor for a plurality of VEM layers <NUM> having varying shear modulus and/or thickness to plot at least one loss factor v. shear modulus/thickness curve. Based on the loss factor v. shear modulus/thickness curve, at least one desired VEM layer <NUM> having a desired shear modulus and/or thickness parameter is determined for at least one desired operating parameter (e.g., frequency and temperature). Strain energy distribution in the at least one desired VEM layer <NUM> is then calculated to determine a distribution of a damping performance along a surface of structural substrate <NUM>. Based on the strain energy distribution, a distribution of VEM layer <NUM> is determined to satisfy predetermined weight and/or cost parameters (e.g., adding and/or removing damping material based on the strain energy distribution, weight, and/or cost). A constraining layer modulus and/or thickness are then independently determined based on a series of models that vary these parameters. For example, the constraining layer parametrics are performed on a model that has at least one desired VEM layer <NUM> having desired shear modulus/thickness properties. Increasing a constraining layer stiffness will in general increase damping performance, cost, and/or weight, and decreasing a constraining layer stiffness will in general decrease damping performance, cost, and/or weight. Based on the constraining layer parametrics, at least one desired constraining layer parameter is determined to satisfy a desired damping performance, weight, and/or cost.

<FIG> is a block diagram of an example computer system <NUM> that may be used to determine a desired structural and/or operating parameter associated with the one or more damping elements <NUM>. In the exemplary embodiment, computer system <NUM> includes a memory device <NUM> and a processor <NUM> coupled to memory device <NUM> for use in executing instructions. More specifically, in the exemplary embodiment, computer system <NUM> is configurable to perform one or more operations described herein by programming memory device <NUM> and/or processor <NUM>. For example, processor <NUM> may be programmed by encoding an operation as one or more executable instructions and by providing the executable instructions in memory device <NUM>.

Processor <NUM> may include one or more processing units (e.g., in a multi-core configuration). As used herein, the term "processor" is not limited to integrated circuits referred to in the art as a computer, but rather broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits.

In the exemplary embodiment, memory device <NUM> includes one or more devices (not shown) that enable information such as executable instructions and/or other data to be selectively stored and retrieved. In the exemplary embodiment, such data may include, but is not limited to, properties of materials, modeling data, calibration curves, operational data, and/or control algorithms. In the exemplary embodiment, computer system <NUM> is configured to automatically implement a finite element analysis to determine a desired structural and/or operating parameter associated with the one or more damping elements <NUM>. Alternatively, computer system <NUM> may use any algorithm and/or method that enable the methods and systems to function as described herein. Memory device <NUM> may also include one or more computer readable media, such as, without limitation, dynamic random access memory (DRAM), static random access memory (SRAM), a solid state disk, and/or a hard disk.

In the exemplary embodiment, computer system <NUM> includes a presentation interface <NUM> that is coupled to processor <NUM> for use in presenting information to a user. For example, presentation interface <NUM> may include a display adapter (not shown) that may couple to a display device (not shown), such as, without limitation, a cathode ray tube (CRT), a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, an "electronic ink" display, and/or a printer. In some embodiments, presentation interface <NUM> includes one or more display devices.

Computer system <NUM>, in the exemplary embodiment, includes an input interface <NUM> for receiving input from the user. For example, in the exemplary embodiment, input interface <NUM> receives information suitable for use with the methods described herein. Input interface <NUM> is coupled to processor <NUM> and may include, for example, a joystick, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), and/or a position detector. It should be noted that a single component, for example, a touch screen, may function as both presentation interface <NUM> and as input interface <NUM>.

In the exemplary embodiment, computer system <NUM> includes a communication interface <NUM> that is coupled to processor <NUM>. In the exemplary embodiment, communication interface <NUM> communicates with at least one remote device. For example, communication interface <NUM> may use, without limitation, a wired network adapter, a wireless network adapter, and/or a mobile telecommunications adapter. A network (not shown) used to couple computer system <NUM> to the remote device may include, without limitation, the Internet, a local area network (LAN), a wide area network (WAN), a wireless LAN (WLAN), a mesh network, and/or a virtual private network (VPN) or other suitable communication means.

The embodiments described herein relate generally to damping mechanisms and, more particularly, to methods and systems for use in damping a panel having a complex contour, such as a cabin air compressor inlet. The embodiments described herein facilitate reducing a vibration and/or noise level associated with a structural substrate. In one embodiment, a damping element includes a VEM layer coupleable to the structural substrate of the aircraft, and a constraining layer coupled to the VEM layer. Accordingly, the embodiments described herein facilitate determining a desired balance between a vibration and/or noise level associated with the structural substrate, and a weight associated with the structural substrate and/or the one or more damping elements.

Further, the disclosure also comprises the following illustrative examples, not to be confused with the appended claims which determine the scope of protection:
In a fourth illustrative example, a method for making a panel for use in an aircraft is provided, said method comprising: coupling a viscoelastic material (VEM) layer to a structural substrate, the VEM layer configured to dampen a vibration of the structural substrate; and coupling a constraining layer to the VEM layer, the constraining layer configured to apply a shear force to the VEM layer.

Optionally, in the method of the fourth illustrative example, coupling a VEM layer to a structural substrate comprises coupling the VEM layer to the structural substrate having at least one surface that is contoured.

Optionally, in the method of the fourth illustrative example, coupling a VEM layer to a structural substrate further comprises coupling the VEM layer to the structural substrate, such that at least a portion of the structural substrate is exposed.

Optionally, the method of the fourth illustrative example further comprises substantially concurrently curing the structural substrate and the VEM layer.

Optionally, the method of the fourth illustrative example further comprises substantially concurrently curing the constraining layer and the VEM layer.

Optionally, the method of the fourth illustrative example further comprises bonding the VEM layer to the structural substrate.

Optionally, the method of the fourth illustrative example further comprises bonding the constraining layer to the VEM layer.

In a fifth illustrative example, a damping element for use in an aircraft is provided, the damping element comprising: a first viscoelastic material (VEM) layer coupleable to a first surface of a structural substrate of the aircraft, the first VEM layer configured to dampen a vibration of the structural substrate; and a first constraining layer coupled to the first VEM layer, the first constraining layer configured to apply a shear force to the first VEM layer.

Optionally, in the damping element of the fifth illustrative example, the first VEM layer is coupleable to the first surface of the structural substrate, such that at least a portion of the structural substrate is exposed.

Optionally, the damping element of the fifth illustrative example further comprises a second VEM layer coupled to the first constraining layer, the second VEM layer configured to further dampen the vibration of the structural substrate, preferably further comprising:
a second constraining layer coupled to the second VEM layer, the second constraining layer configured to apply a shear force to the second VEM layer.

Optionally, the damping element of the fifth illustrative example further comprises a second VEM layer coupleable to a second surface of the structural substrate, the second VEM layer configured to further dampen the vibration of the structural substrate, preferably further comprising:
a second constraining layer coupled to the second VEM layer, the second constraining layer configured to apply a shear force to the second VEM layer.

In a sixth illustrative example, a panel for use in an aircraft is provided, the panel comprising: a structural substrate having a first surface; a first viscoelastic material (VEM) layer coupled to the first surface of the structural substrate, the first VEM layer configured to dampen a vibration of the structural substrate; and a first constraining layer coupled to the first VEM layer, the first constraining layer configured to apply a shear force to the first VEM layer.

Optionally, in the panel of the sixth illustrative example, the structural substrate has at least one surface that is contoured.

Optionally, in the panel of the sixth illustrative example, the first VEM layer is coupled to the first surface of the structural substrate, such that at least a portion of the structural substrate is exposed.

Optionally, the panel of the sixth illustrative example further comprises a second VEM layer coupled to the first constraining layer, the second VEM layer configured to further dampen the vibration of the structural substrate, preferably further comprising:
a second constraining layer coupled to the second VEM layer, the second constraining layer configured to apply a shear force to the second VEM layer.

Optionally, the panel of the sixth illustrative example further comprises a second VEM layer coupled to a second surface of the structural substrate, the second VEM layer configured to further dampen the vibration of the structural substrate, preferably further comprising:
a second constraining layer coupled to the second VEM layer, the second constraining layer configured to apply a shear force to the second VEM layer.

Exemplary embodiments of methods and systems for damping a cabin air compressor inlet are described above in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the method may be utilized independently and separately from other components and/or steps described herein. Each method step and each component may also be used in combination with other method steps and/or components. Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

Claim 1:
An aircraft cabin air compressor, CAC inlet (<NUM>), comprising a panel (<NUM>) that forms at least a portion of a shell of the CAC inlet (<NUM>), the panel comprising a structural substrate (<NUM>) having a first surface, and coupled thereto a damping element (<NUM>) for damping vibration and/or noise, the damping element (<NUM>) comprising:
a first viscoelastic material, VEM, layer (<NUM>) coupled to the first surface of the structural substrate (<NUM>) of the aircraft CAC inlet (<NUM>), the first VEM layer (<NUM>) configured to dampen a vibration of the structural substrate (<NUM>); and
a first constraining layer (<NUM>) coupled to the first VEM layer (<NUM>), such that the first constraining layer (<NUM>) encapsulates the VEM layer (<NUM>), the first constraining layer (<NUM>) configured to apply a shear force to the first VEM layer (<NUM>).