Automated production of acoustic structures

Abstract

A laser cuts overlapping ribbons of acoustic material into acoustic devices. An automatically controlled manipulator includes an end effector having groups of placement tools for simultaneously placing multiple acoustic devices in a cellular core. The placement tools include mandrels provided with vacuum pickups for picking up and holding the acoustic devices during transport to the core. A vision system aligns the placement tools with the cells of the core. The end effector includes a thermal radiation device for bonding the acoustic devices to the core.

Claims

1. A method of automated production of an acoustic core having a plurality of cells, comprising: fabricating a plurality of acoustic devices, wherein fabricating the plurality of acoustic devices comprises overlaying ribbons of acoustic material, laser cutting the ribbons of acoustic material into a shape of the acoustic devices and joining cut edges of the ribbons of acoustic material together; picking up groups of the acoustic devices; placing the groups of the acoustic devices respectively in cells of the core; and bonding the acoustic devices to the core.

2. The method of claim 1, wherein picking up groups of the acoustic devices includes: inserting a plurality of mandrels respectively into the acoustic devices, and holding the acoustic devices on the mandrels using suction force.

3. The method of claim 1, wherein placing the groups of the acoustic devices respectively into cells of the core includes using a vision system to align the acoustic devices with the cells.

4. The method of claim 1, wherein bonding the acoustic devices to the core includes directing thermal radiation onto the acoustic devices after the acoustic devices have been placed in the core.

5. The method of claim 1, wherein the overlaying ribbons of acoustic material comprises overlaying ribbons of acoustic material to provide double layers of acoustic material ribbons.

6. The method of claim 5, wherein the double layers of acoustic material ribbons are arranged in alternating, mirror image patterns.

7. A method of installing a generally hollow acoustic device in a cell of a cellular core, comprising: inserting a tool into the acoustic device, using a vacuum to hold the acoustic device on the tool, wherein inserting the tool into the acoustic device includes using a tip of the tool to spread apart the end of the acoustic device into which the tool may be inserted; shaping an end of the acoustic device to match a shape of the cell; picking up the acoustic device using the tool; and placing the acoustic device in a cell using the tool.

8. The method of claim 7, wherein shaping an end of the acoustic device includes inserting a plurality of fingers into the end of the acoustic device.

9. The method of claim 8, wherein inserting a plurality of fingers is performed by sliding the fingers over the tool into the acoustic device after the tool has been inserted into the acoustic device.

10. The method of claim 7, further comprising: applying an adhesive to the acoustic device, and bonding the acoustic device to the cell, including curing the adhesive by directing radiation from the tool onto the adhesive.

11. A method of automated production of an acoustic core having a plurality of cells, comprising: fabricating a plurality of acoustic devices, wherein fabricating the plurality of acoustic devices includes: overlaying ribbons of acoustic material, and laser cutting the ribbons in a shape of the acoustic devices and welding together edges of the ribbons surrounding at least a portion of each of the acoustic devices, and wherein the method further comprises: picking up groups of the acoustic devices; placing the groups of the acoustic devices respectively in cells of the acoustic core; and bonding the acoustic devices to the acoustic core.

12. The method of claim 11, wherein picking up groups of the acoustic devices includes: inserting a plurality of mandrels respectively into the acoustic devices, and holding the acoustic devices on the mandrels using suction force.

13. The method of claim 11, wherein placing the groups of the acoustic devices respectively into cells of the acoustic core includes using a vision system to align the acoustic devices with the cells.

14. The method of claim 11, wherein bonding the acoustic devices to the acoustic core includes directing thermal radiation onto the acoustic devices after the acoustic devices have been placed in the acoustic core.

15. The method of claim 11, wherein picking up and placing is performed by a manipulator upon which is mounted an end effector including a plurality of acoustic device placement tools each capable of placing an acoustic device in one of the cells of the acoustic core, and wherein the method further comprises: transmitting a set of digital instructions from a digital controller to control movement of the manipulator and operation of the end effector.

16. The method of claim 11, wherein the overlaying ribbons of acoustic material comprises overlaying ribbons of acoustic material to provide double layers of acoustic material ribbons.

17. A method of installing an acoustic device in a cell of a cellular core, wherein the acoustic device is generally hollow, the method comprising: inserting a tool into the acoustic device, using a vacuum to hold the acoustic device on the tool; shaping an end of the acoustic device to match a shape of the cell using a shaper comprising a plurality of fingers slidable over the tool and into the acoustic device; picking up the acoustic device using the tool; and placing the acoustic device in a cell using the tool.

18. The method of claim 17, wherein inserting the tool into the acoustic device includes using a tip of the tool to spread apart the end of the acoustic device into which the tool may be inserted.

19. The method of claim 17, wherein shaping an end of the acoustic device includes inserting the plurality of fingers into the end of the acoustic device.

20. The method of claim 19, wherein inserting a plurality of fingers is performed by sliding the fingers over the tool into the acoustic device after the tool has been inserted into the acoustic device.

21. The method of claim 17, further comprising: applying an adhesive to the acoustic device, and bonding the acoustic device to the cell, including curing the adhesive by directing radiation from the tool onto the adhesive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims. The illustrative embodiments, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 is an illustration of a perspective view of a septumized cellular core, portions of the cell walls being broken away to reveal individual septums.

(3) FIG. 2 is an illustration of a cross-sectional view of a portion of the acoustic liner.

(4) FIG. 3 is an illustration of a block diagram of a system for producing acoustic structures.

(5) FIG. 4 is an illustration of a perspective view showing acoustic and adhesive ribbons the drawn onto a cutting table.

(6) FIG. 5 is an illustration similar to FIG. 4, but showing ribbons having been drawn down on the cutting table and a laser having cut the ribbons into a group of individual septums.

(7) FIG. 6 is an illustration of a perspective view of an end effector mounted on a robot.

(8) FIG. 7 is an illustration of an end elevational is view of the end effector, wherein the folded position of the placement tools is indicated in broken lines.

(9) FIG. 8 is an illustration of a side elevational view of the end effector shown in FIG. 7.

(10) FIG. 9 is an illustration of a perspective view of the end effector positioned to pick up a group of the individual septums.

(11) FIG. 10 is an illustration of an enlarged perspective view showing the placement tools in the process of picking up the septums.

(12) FIG. 11 is an illustration of an end elevational view of the end effector, showing the placement tools in the fully folded position.

(13) FIG. 12 is an illustration similar to FIG. 11 but showing one bank of the placement tools having partially rotated in preparation for picking up one set of the septums.

(14) FIG. 13 is an illustration similar to FIG. 11, but showing the other bank of the placement tools having been partially rotated in preparation for picking up the other set of septums.

(15) FIG. 14 is an illustration of a side elevational view showing one of the placement tools about to pick up one of the septums.

(16) FIG. 15 is an illustration similar to FIG. 14 but showing the placement tool having spread and entered the septum.

(17) FIG. 16 is an illustration similar to FIG. 15 but showing forming fingers on the placement tool having shifted into and formed the open end of the septum.

(18) FIG. 17 is an illustration of an isometric view showing a curved segment of a cellular core in which septa are to be placed by the end effector.

(19) FIG. 18 is an illustration of a perspective view showing the end effector having positioned the placement tools above individual cells of the core.

(20) FIG. 19 is an illustration of an isometric view showing how the vision system aligns the placement tools relative to the cells, and wherein one of the septums is being placed in a cell by one of the placement tools.

(21) FIG. 20 is an illustration of a perspective view showing curing of the adhesive by radiant thermal energy.

(22) FIG. 21 is illustration of an enlarged perspective view, better showing how radiant thermal energy is transmitted from the placement tool to the area of the adhesive.

(23) FIG. 22 is an illustration of a diagrammatic view showing thermal radiant energy used to bond the acoustic device to the cellular core, portions of a cell wall being broken away to reveal an adhesive ribbon.

(24) FIG. 23 is an illustration of a perspective view of a portion of the cellular core shown in FIG. 17 after several septums have been placed and bonded in place.

(25) FIG. 24 is an illustration of a flow diagram of a method of automated production of acoustic structures.

(26) FIG. 25 is an illustration of a flow diagram of aircraft production and service methodology.

(27) FIG. 26 is an illustration of a block diagram of an aircraft.

DETAILED DESCRIPTION

(28) The disclosed embodiments relate to a method and apparatus for automated production of acoustic structures such as a cellular acoustic core containing large quantities of acoustic devices. For example, referring to FIG. 1, an acoustic structure 30 has a cellular acoustic core 32, sometimes referred to herein as a honeycomb core, containing a multiplicity of individual cells 42. Each of the cells 42 contains a generally hollow acoustic device 34 for altering the acoustic characteristics of the cellular core 32, such as sound attenuation. In the illustrated example, the acoustic device 34 comprises a discrete, cone shaped septum 34 that is bonded to the cellular core 32, however other types of acoustic devices 34 may be installed in the cellular core 32 using the method and apparatus described below.

(29) Referring now to FIG. 2, the disclosed method and apparatus may be used, for example and without limitation, to septumize a cellular core 32 of an acoustic structure 30 employed as an acoustic liner 30. The acoustic liner 30 may be used in various parts of a jet engine to attenuate noise. The acoustic liner 30 is a sandwich panel construction broadly comprising a honeycomb core 32 sandwiched between inner and outer facesheets 36, 38 respectively. The inner facesheet 36 includes a multiplicity of perforations 40 therein which allow sound waves, including noise to pass through the inner facesheet 36 into the cellular core 32. The inner facesheet 36 is attached to the top of the cellular core 32 by any suitable process such as adhesive bonding. Similarly, the outer facesheet 38 may be attached to the bottom the cellular core 32 by adhesive bonding.

(30) In the illustrated embodiment, the inner and outer facesheets 36, 38 each may comprise a composite laminate such as a CFRP (carbon fiber reinforced plastic) however, either of these facesheets may comprise other materials. The honeycomb core 32 is formed of a multiplicity of individual polygonal cells 42 which are defined by a number of cell walls 44. In the illustrated example, the cells 42 are hexagonal, however other cell geometries are possible. The honeycomb core 32 is septumized by a plurality of individual composite septums 34 which are precisely placed in, and bonded to the core 32 using the method and apparatus described below. The septums 34 are perforated or may be formed from a porous material such as a mesh which allows a portion of the sound waves to pass through the septums 34, downwardly through the cells 42 toward the outer facesheet 38.

(31) The individual septums 34, which may be collectively referred to as septa 34, have an upper section 46 and a lower section 48. The upper section 46 of the septa 34 have substantially the same cross-sectional shaped as the cells 42 (hexagonal in the illustrated embodiment) and are adhesively bonded to the cell walls 44, thereby fixing the position of the septa 34 within the cells 42. In the illustrated embodiment, the cell walls 44 and the septa 34 may be formed of a composite fabric (woven or knitted) such as a PEEK thermoplastic, however other materials are possible.

(32) The lower section 48 of the generally hollow septa 34 extends down into the cells 42 a desired depth, forming cavities 50 within the cells 42 of a preselected the volume, shape and surface area which achieve a desired acoustic performance for a chosen application. For example, the size, shape and surface area of the septa 34 may be selected to form resonant cavities 50 that assist in canceling or damping sound waves/noise flowing over the acoustic structure 30 which enter cellular core 32 through the perforations 40 in the inner facesheet 36.

(33) In the illustrated embodiment, the lower section 48 of the septa 34 is generally conical in shape, however the septa 34 may have other shapes which may be constant or varying over the area of the cellular core 32, allowing the acoustic structure 30 to be tuned in different areas to attenuate different types of noise, such as noises in different frequency ranges. Also, while the upper sections 46 of the septa 34 are positioned at the top of the cells 42 in the illustrated embodiment, in other embodiments the septa 34 may be positioned lower within the cells 42 such that the upper sections 46 are spaced below the top of the cells 42. As previously pointed out, the septa 34 are merely illustrative of a wide range of acoustic device 34 that can be installed in the cellular core 32 according to the disclosed method.

(34) Attention is now directed to FIG. 3 which broadly illustrates the functional components of apparatus 55 for automated production of acoustic structures 30 having a multiplicity of individual cells 42 containing generally hollow acoustic devices 34 such as septa. The apparatus 55 comprises a material supply system 56, automatically controlled laser cutter/welder 62, an end effector 60, and a digital controller 80. The material supply system 56 provides a supply of acoustic material sheets in the form of ribbons of acoustic material 58, and a supply of adhesive in the form of ribbons of adhesive material 65. The acoustic ribbons 58 are cut into the desired shape of individual acoustic devices 34 by the laser cutter/welder 62. The adhesive ribbons 65 (hereafter sometimes referred to as adhesive) are applied to the individual septums 34 for use in bonding the acoustic devices 34 within the individual cells 42 of the cellular core 32. While the bonding adhesive 65 is shown as ribbons in the illustrated embodiment, in other embodiments the adhesive 65 may be in other forms such a paste adhesive, a liquid adhesive or strips of an adhesive that are applied to the acoustic devices 34 using any of a variety of techniques. The laser cutter/welder 62 is mounted on a manipulator 64 which may comprise a robot (not shown), gantry (not shown) or similar machine that is digitally controlled by the controller 80 and is capable of moving the laser cutter/welder 62 on a desired programmed path. As will be discussed below, the laser cutter/welder 62 acts both as a cutter that cuts sheets of the acoustic material into desired shapes, and as a joiner that joins edges of the sheets after they have been cut to the desired profile shape.

(35) The end effector 60 is mounted on a manipulator 66 which may be the same or different than the manipulator 64 used to control the laser cutter/welder 62. In the illustrated example, as will be discussed below, the manipulator 66 comprises a robot having multiple degrees of freedom and capable of moving the end effector 60 along multiple axes, under control of the digital controller 80. The digital controller 80 may comprise, for example and without limitation, a PC (personal computer), a general-purpose program computer or a PLC (programmable logic controller). The digital controller 80 may include, or have access to a set of digital programmed instructions 82 in the form of one or more software programs.

(36) The end effector 60 includes a machine vision system 72, a plurality of acoustic device placement tools 68, a vacuum system 70 and one or more curing devices 78 which may comprise a radiation generator. Each of the acoustic device placement tools 68 is coupled with the vacuum system 70 which functions to hold the acoustic device 34 until it has been placed and bonded within a cell 42. The machine vision system 72 may include a laser 74 for directing a laser spot (not shown) onto the cellular core 32, and a camera system 76 for viewing the core 32, and detecting the laser spot as well as other details of the cellular core 32 required for aligning and accurately placing the acoustic devices 34 in the core cells 42. Each of the curing devices 78 is operative to generate radiation that cures the adhesive 65 during the installation process in order to bond the acoustic device 34 to the cell walls 44 (FIG. 2) of the cell 42 in which it has been installed. The radiation generated by the curing device 78 may be thermal (e.g. infrared), UV (ultraviolet) or other wavelengths suitable for curing the particular adhesive 65 that is chosen for the application.

(37) Attention is now directed to FIGS. 4 and 5 which illustrate additional details of the material supply system 56, and a process for producing acoustic devices 34 using the laser cutter/welder 62. The material supply system 56 broadly comprises two spools 84, 86 of acoustic ribbons 58, and two spools 90 of adhesive 65. Ribbons of the acoustic material 58 are drawn from the spools 84, 86 and brought into overlapping relationship, forming a double layer of acoustic material, before being drawn through a pair of pinch rollers 93 onto a flat table 95. The table 95 may be a perforated air table coupled with a vacuum which draws the double layers of acoustic material tightly down onto the table 95 in order to eliminate wrinkling and hold the double layers flat during subsequent processing.

(38) The adhesive 65, which may be in ribbon or other forms, is drawn off the spools 90 in laterally spaced relationship and is aligned with the outer edges of the acoustic material ribbons 58, before being drawn through the pinch rollers 93 onto the outer edges of the double layers of acoustic material ribbons 58. The laser cutter/welder 62, operated by the digital controller 80 (FIG. 3), cuts the double layers of acoustic material into stacked, individual pieces having the shape of the acoustic devices 34, arranged in alternating, mirror image patterns. The ribbon of adhesive 65 may be cut by the laser cutter/welder 62 along with the ribbon 58 of acoustic material. As the laser cutting is being performed, the heat produced by the laser cutter/welder 62 welds and joins the cut edges of the two layers together. While a laser cutter/welder 62 has been disclosed, other techniques for cutting the ribbons 58 of acoustic material and the adhesive 65 into the shape of the septums 34, and then sealing the cut edges may be employed. Moreover, as previously mentioned, the adhesive 65 may be in forms other than ribbons, and may be applied to the acoustic devices 34 using any of a variety of other techniques.

(39) Referring now to FIGS. 6, 7 and 8, the end effector 60 comprises a frame 92 mounted on an arm of a robot 66 that is movable along a track 98. The end effector 60 includes a plurality of placement tools 68 which pick up the generally hollow acoustic devices 34 from the table 95 (FIGS. 4 and 5) and transport them to a later described cellular core where the placement tools 68 are used to place and bond the acoustic devices 34 in the core cells 42.

(40) As best seen in FIG. 7, the placement tools 68 are arranged in two opposing banks 100, 102, each comprising a plurality of the placement tools 68 which are aligned and spaced apart from each other distances d corresponding to the spacing between the core cells 42. Similarly, the banks 100, 102 are spaced apart from each other a distance D corresponding to a predetermined multiple of the spacing between the core cells 42. The placement tools 68 in each of the banks 100, 102 are pivotally mounted on a shaft 94 fastened at its opposite ends to hangers 96 secured to and extend downwardly from the frame 92.

(41) Each of the placement tools 68 comprises a conically shaped, foot-like mandrel 104 having vacuum pickups 120 that are connected to the vacuum system 70 (FIG. 3). A spindle 106 connects each of the mandrels 104 with a mounting block 108 which, in turn, is pivotally mounted on one of the shafts 94, thereby mounting the placement tools 68 for pivotal movement 114 between an acoustic device pick-up position (broken lines in FIG. 7), and an acoustic device placement position.

(42) A shaper 110 is sleeved over and linearly displaceable along each of the spindles 106. Each of the shapers 110 includes a plurality of circumferentially spaced apart shaping fingers 112 having outer tips that are configured to substantially match the geometry of the cell walls 44 (FIG. 2) of the core 32. The shapers 110 are pneumatically actuated through pneumatic lines 116, while the vacuum pickups 120 are coupled with the vacuum system 70 by vacuum lines 118 to produce a suction force that holds the acoustic devices on the mandrels 104.

(43) It should be noted here that the placement tools 68 described above are merely illustrative of tools that may be mounted on the end effector 60 and used to pick and place the acoustic devices 34 in the core cells 42. The exact configuration and features of the placement tools 68 may vary depending on the application, the size and shape of the acoustic devices 34 and the geometry of the core cells 42. Moreover, the number of the placement tools 68 that are mounted on the end effector 60 may vary with the application. In some applications, a single one of the placement tools 68 may be satisfactory and effective in placing acoustic devices 34 in core cells 42.

(44) Attention is now directed to FIGS. 9-16 which illustrate the operation of the end effector 60 during pickup of the acoustic devices 34 from the table 95. The pickup sequence involves lateral shifting 122 (FIG. 9) of the end effector 60, back-and-forth across the ribbon of acoustic material 58 that has been cut into individual acoustic devices 34. With the two banks 100, 102 of placement tools 68 in their folded position shown in FIG. 11, the end effector 60 is lowered to a position that is slightly above the surface of the table 95, as best seen in FIG. 9.

(45) Next, as shown in FIGS. 9 and 12, one of the banks 102 is partially pivoted 115 downwardly (see FIG. 12) to align the end of the mandrels 104 with the open ends 125 (FIG. 14) of the acoustic devices 34 of one bank 102 thereof, which at this stage, are in a collapsed, flat state. Next, the end effector 60 is laterally shifted 122 (FIG. 9), causing the mandrel 104 to enter the open end 125, and then spread apart the acoustic device 34, as shown in FIGS. 10 and 15. The vacuum pickup 120 is then actuated, causing the hollow acoustic device 34 to be sucked toward and drawn against the mandrel 104, thereby holding the acoustic device 34 against the tool 68.

(46) Next, as shown in FIG. 16, the shaper 109 is shifted 130 into the open end 125 of the acoustic device 34, causing the fingers 112 to shape the periphery 132 of acoustic device 34 to substantially match the cross-sectional shape of the core cells 42 which, in the illustrated example is hexagonal. After one set of the acoustic devices 34 have been picked up by one bank 102 of the placement tools 68, the bank 102 is rotated to the transport position shown in FIG. 13, and the other bank 100 is rotated to its pickup position, following which the placement tools 68 in bank 100 proceed to pick up the remaining set of acoustic devices 34 from the table 95.

(47) Referring now to FIGS. 17-19, with a full set of the acoustic devices 34 having been picked up by the end effector 60, the robot 66 (FIG. 17) transports the end effector 60 to the vicinity of the core 32, which, in the illustrated example is curved. One or more laser guidance spots are directed from the end effector 60 onto the cellular core 32, and a camera system 76 (FIG. 3) views the surface of the cellular core 32 and detect laser spots. The vision system 72 along with the digital controller 80 cooperate to adjust 134 (FIG. 19) the position of the end effector 60 such that the placement tools 68 are precisely aligned with the centerlines of a group of the core cells 42.

(48) With the placement tools 68 having been aligned with the core cells 42, the end effector 60 displaces the placement tools 68 toward the core 32, thereby placing and inserting the acoustic devices 34 in a chosen set of the core cells 42. The acoustic devices 34 are inserted to a desired, preprogrammed depth within the core cells 42, which in the illustrated example results in the top of the acoustic devices 34 being located at the top of the core cells 42 (see FIGS. 1 and 2).

(49) Attention is now directed to FIGS. 20-22 which illustrate the process for adhesively bonding the acoustic devices 34 to the cellular core 32 after the end effector 60 has placed a set of the acoustic devices 34 within the cells 42. A curing device 78 surrounds each of the spindles 106 and is operative to direct thermal radiation 138, or other forms of radiation, onto the top of the acoustic devices 34. The thermal radiation 138 heats the adhesive 65 surrounding the acoustic device 34 to the cure temperature of the adhesive, thereby bonding the acoustic device 34 to the cell walls 44.

(50) In one embodiment, each of the curing devices 78 may comprise a laser diode or a ring of laser diodes, however other types of devices cap the adhesive 65 may be employed. Also, while the curing devices 78 are mounted on the placement tools 68 in the illustrated embodiment, it may be possible to mount the curing devices 78 at other locations on the end effector 60. Depending upon the type of adhesive 65 being employed, it may be possible to achieve curing of the adhesive using other types of radiation, such as ultrasonic, UV or other form of energy.

(51) After the acoustic devices 34 have been bonded within the core cells 42, the vacuum holding the acoustic devices 34 on the placement tools 68 is removed, thereby releasing the acoustic devices 34 from placement tools 68. Once the vacuum is removed, the end effector 60 moves upwardly away from the cellular core 32, withdrawing the placement tools 68 from the acoustic devices 34. In some applications, slight positive pressure may be applied through the vacuum pickups 120 (see FIG. 14) to assure that there is a full release of the acoustic devices 34 from the placement tools 68. FIG. 23 illustrates a cellular core 32 in which a set of the acoustic devices 34 have been placed and bonded within core cells 42.

(52) FIG. 24 illustrates the overall steps of a method of placing in bonding a plurality of acoustic devices 34 in a cellular core 32, employing embodiments of the apparatus described above. Beginning at 140, a plurality of acoustic devices 34 are fabricated, using a laser 62 or other device to cut out and perimeter weld each of the devices 34. At 142 groups of the acoustic devices 34 are picked up using placement tools 68 having vacuum pickups 120 that holds the acoustic devices 34 on mandrels 104 forming part of the placement tools 68.

(53) At 144 the groups of the acoustic devices 34 that have been picked up, are then placed respectively in cells 42 of the core 32. A machine vision system 72 along with an automatically controlled the end effector 60 is used to precisely align and place the acoustic devices 34 in the core cells 42. At 146, the acoustic devices 34 are adhesively bonded to the core 32 using thermal, UV or other form of radiation 138 to activate a bonding adhesive 65 applied to the acoustic devices 34.

(54) Embodiments of the disclosure may find use in a variety of potential applications, particularly in the transportation industry, including for example, aerospace, marine, automotive applications and other application where acoustic treatments, such as acoustic liners, may be used. Thus, referring now to FIGS. 25 and 26, embodiments of the disclosure may be used in the context of an aircraft manufacturing and service method 148 as shown in FIG. 25 and an aircraft 150 as shown in FIG. 26. Aircraft applications of the disclosed embodiments may include, for example, without limitation, acoustic liners for sound attenuation in jet engines. During pre-production, exemplary method 148 may include specification and design 152 of the aircraft 150 and material procurement 154. During production, component and subassembly manufacturing 156 and system integration 158 of the aircraft 150 takes place. Thereafter, the aircraft 150 may go through certification and delivery 160 in order to be placed in service 162. While in service by a customer, the aircraft 150 is scheduled for routine maintenance and service 164, which may also include modification, reconfiguration, refurbishment, and so on.

(55) Each of the processes of method 148 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.

(56) As shown in FIG. 26, the aircraft 150 produced by exemplary method 148 may include an airframe 166 with a plurality of systems 168 and an interior 170. Examples of high-level systems 168 include one or more of a propulsion system 172, an electrical system 174, a hydraulic system 176 and an environmental system 178. Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the marine and automotive industries.

(57) Systems and methods embodied herein may be employed during any one or more of the stages of the production and service method 148. For example, components or subassemblies corresponding to production process 156 and 158 may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft 150 is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages 156 and 158, for example, by substantially expediting assembly of or reducing the cost of an aircraft 150. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft 150 is in service, for example and without limitation, to maintenance and service 164.

(58) As used herein, the phrase at least one of, when used with a list of items, means different combinations of one or more of the listed items may be used and only one of each item in the list may be needed. For example, at least one of item A, item B, and item C may include, without limitation, item A, item A and item B, or item B. This example also may include item A, item B, and item C or item B and item C. The item may be a particular object, thing, or a category. In other words, at least one of means any combination items and number of items may be used from the list but not all of the items in the list are required.

(59) The description of the different illustrative embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different illustrative embodiments may provide different advantages as compared to other illustrative embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.