Patent ID: 12220884

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the presented concepts. In some examples, the presented concepts are practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail so as to not unnecessarily obscure the described concepts. While some concepts will be described in conjunction with the specific examples, it will be understood that these examples are not intended to be limiting.

Introduction

Composite stringers and other shaped composite structures are used for many applications, such as aircraft, land vehicles, and the like. Fabrication of these composite structures involves various handling and processing of pre-cured shaped components, such as trimming, inspection, bladder installations, and such. Prior to curing, these shaped components require sufficient support to retain the shape, which can be challenging due to differences in shapes and sizes of these pre-cured components. For example, a modern aircraft uses hundreds of different composite stringers, which have different sizes, cross-sectional shapes, in-plane bends, and/or out-of-plane bends. Providing a dedicated support for each type of these composite stringers is challenging and expensive, adding to an already large number of specialized tools used in fabrication of composite stringers.

FIGS.1A and1Billustrate two process flowcharts representing different examples of fabrication a composite stringer and corresponding tools used for various operations.FIGS.1A and1Bare presented to provide some context and general overview of key components, tools, and steps. In both examples, the process starts with forming device510shaping composite layup502, thereby forming pre-cured composite stringer190. Curing device540then cures pre-cured composite stringer190, thereby forming composite stringer198. Pre-cured composite stringer190and composite stringer198have the generally same shape, but different material and mechanical properties. For example, the resin of pre-cured composite stringer190is not fully crosslinked or not as cross-inked as the resin of composite stringer198. As such, pre-cured composite stringer190is still able to change the shape and requires support before curing.

Both forming device510and curing device540are specifically shaped to accommodate a particular design of composite stringer198. Therefore, either one or both of forming device510and curing device540can be used for supporting pre-cured composite stringer190after completing the forming operation and before initiating the curing operation, which corresponds to the example shown inFIG.1A. However, this approach occupies one or both forming device510and curing device540for operations that are not core functions of these devices. Furthermore, many of these operations and even storage of pre-cured composite stringer190may take significant periods of time. As a result, the throughput of one or both forming device510and curing device540can be limited by these intermediate operations and storage associated with pre-cured composite stringer190.

Referring toFIG.1B, post-forming processing device100is used to receive pre-cured composite stringer190after pre-cured composite stringer190is formed/shaped. Post-forming processing device100is also used to support pre-cured composite stringer190up until the curing operation. Post-forming processing device100effectively relieves forming device510and curing device540, increasing their processing throughputs. Post-forming processing device100is used for various operations, performed on pre-cured composite stringer190, and, in some examples, for storing pre-cured composite stringer190.

However, if a post-forming processing device is specifically and permanently shaped for accommodating the shape of each specific composite stringer, then the numbers of such post-forming processing devices would be the same as the number of different stringers. This approach is not desirable from a space and cost savings perspective and can complicate the overall process by requiring a large number of additional tools. Furthermore, post-forming processing devices, which are specifically and permanently shaped, may not be always stackable due to the design variations, which complicates their storage. It should also be noted that the supply base is limited based on complexity of the post-forming processing device. Also, 3-D geometry increases complexity for shuttling the stringers around. Finally, 3-D geometry likely increases weight which will inhibit manual handling for a variety of reasons including maintenance.

Design variations of composite stringers or, more specifically, different examples of pre-cured composite stringer190are shown inFIGS.1C,1D, and1E. In each example, pre-cured composite stringer190comprises flange portions196, which define contact surface197. Contact surface197is used for connecting the composite stringer, formed from pre-cured composite stringer190, to other components, e.g., a composite skin of an aircraft. These other components define the shape of contact surface197. In some examples, contact surface197is planar. Alternatively, contact surface197and, more generally, the entire stringer has an out-of-plane bend.

Each of pre-cured composite stringers190also comprises hat portion191, which interconnects and is positioned between flange portions196. Hat portion191extends away from contact surface197, defining stringer cavity192. Hat portion191is defined by the height (H) of hat portion191, which is defined as a maximum deviation from contact surface197. Hat portion191is also defined by the width (W) of hat portion191, which is defined as the gap between flange portions196.

Referring toFIG.1C, in some examples, hat portion191is formed by straight walls. Alternatively, in some examples, hat portion191is formed by a continuous curved wall, e.g., as shown inFIG.1E.FIG.1Dillustrates an example where hat portion191is formed by a combination of straight and curved walls.FIGS.1C,1D, and1Eillustrate that pre-cured composite stringers190, shown in these figures, require different types of support from post-forming processing device100. Furthermore,FIGS.1C,1D, and1Eillustrate that pre-cured composite stringers190are not stackable. Therefore, if permanently-rigid supports are used for these pre-cured composite stringers, these supports will not be stackable either. For purposes of differentiating pre-cured composite stringers, an example shown inFIG.1Emay be referred to as additional pre-cured composite stringers199. Processing different types of pre-cured composite stringers using the same post-forming processing device100is described below with reference toFIG.4.

Described methods and devices are used for supporting of variety of different pre-cured composite stringers, such as ones shown inFIGS.1A-1C. More specifically, the same post-forming processing device is configured to support pre-cured composite stringers with different cross-sectional profiles of their hat portions. Specifically, a post-forming processing device comprises a channel and a support structure, at least partially extending within the channel. The support structure is configured to conform to each of differently shaped hat portions the pre-cured composite stringers and to retain the shape of these hat portions while providing the support. In some example, the support structure is made from a flexible material that conforms to any shape of the hat portions. Alternatively, the support structure is made from a jamming material and is reshaped together with each of the pre-cured composite stringers.

Within examples of the present disclosure, the disclosed post-forming processing device is used for supporting different pre-cured composite stringers while various operations are performed on these stringers, such as stringer trimming, inspection, installation of bladders and noodles, and the like. Furthermore, in some examples, the disclosed post-forming processing device is used for storing pre-cured composite stringers. Overall, adding the disclosed post-forming processing device into the overall process flow allows increasing processing throughputs of other devices, such as forming devices and curing devices. Overall, the disclosed post-forming processing devices provide high rate automation of stringer installation by merging the gap between forming and curing devices with these post-forming processing devices.

The described methods also incorporate alignment fittings to ensure the proper alignment between the stringer and the bladder for dead end fittings. Offset of the bladder helps to provide proper support and functionality during cure. For example, in some instances, a bladder is terminated inside of the edge of the part. Specific examples include door structures, window structures, and convergence structures (e.g., aircraft structures with pointy ends).

It should be noted that the cavity is tools used for forming stringer, accommodate both a stringer and a bladder. If the bladder does not extend past the stringer, the bladder will either interfere or leave an unacceptably large gap inside the tool. Since the bladder is aligned and locked to the stringer at the kitting stage, it is beneficial for that the bladder be indexed in the correct position to avoid rework at later stages.

Additionally, some bladders receive one or more layers of material wrapped around these bladders prior to insertion to corresponding stringers. In some examples, this assembly includes a glass ply, aligned to the end of the stringers to add the corrosion protection inside the stringer. In other examples, this assembly includes a carbon wrap, which adds strength to the stringer. In these later examples, the bladder wrap is aligned with the stringer.

Examples of Post-Forming Processing Device

FIG.2Ais a schematic cross-sectional view of post-forming processing device100for supporting pre-cured composite stringers190, in accordance with some examples. Post-forming processing device100comprises base110, support structure120, and, optionally, cover130. In some examples, post-forming processing device100does not have or, at least, is used in some operations without cover130.

Base110is formed from a rigid material, such as carbon fiber, aluminum, a pultruded polyester/glass solution, and the like. Base110comprises support surface114, which faces cover130, when cover130is present. Support surface114is configured to seal against cover130and, in some examples, comprises one or more sealing features. During the operation of post-forming processing device100, support surface114is used to support flange portions196of stringer190, e.g., by compressing flange portions196between support surface114and cover. In some examples, support surface114is planar. In general, support surface114conforms to the shape of flange portions196of stringer190.

Base110also comprises channel112, partially extending through base110and having opening113. Opening113separates two portions of support surface114. As shown inFIG.2A, channel112has a channel width (CW) and a channel height (CH). The channel width (CW) is measured in the direction parallel to support surface114(along the Y axis). The channel height (CH) is measured in the direction perpendicular to support surface114(along the Z axis). In some examples, the channel width (CW) is constant along the length (the X axis (see, e.g.,FIG.2F)) of base110. In the same or other examples, the channel height (CH) is constant along the length (the X axis) of base110. In some examples, the channel width (CW) is constant along the channel height (the Z axis) as, for example, shown inFIG.2A. This type of channel112may be referred to as a straight channel. Alternatively, the channel width (CW) differs along the channel height (the Z axis) as, for example, shown inFIG.2E. In this example, the channel width (CW) is the greatest at opening113. This type of channel112may be referred to as a tapered channel and allows for stacking post-forming processing device100.

Channel112is used to accommodate hat portion191of pre-cured composite stringer190when pre-cured composite stringer190is supported using post-forming processing device100. Referring toFIG.2B, hat portion191protrudes into channel112, while flange portions196rest on support surface114. It should be noted that the same post-forming processing device100is used for supporting different types of pre-cured composite stringers190, which may have different shapes and sizes of hat portions191. As such, the channel width (CW) is larger than the width of hat portions191of pre-cured composite stringers190or, more specifically, larger than the width of the widest hat portion191among all pre-cured composite stringers190, processed on post-forming processing device100. For purposes of this disclosure, the width of hat portion191is defined as the largest width, e.g., when hat portion191has a tapered or curved cross-section. Furthermore, the channel height is larger than the height of hat portion191of pre-cured composite stringers190or, more specifically, larger than the height of the tallest hat portion191among all pre-cured composite stringers190, processed on post-forming processing device100. In general, the cross-sectional profile of channel112is sufficient to accommodate any hat portion191of stringer190, processed using post-forming processing device100.

WhileFIGS.2A-2Cillustrate a rectangular cross-sectional profile of channel112, any cross-sectional profile capable of accommodating hat portions191of pre-cured composite stringers190is within the scope of the present disclosure, such as tapered profile shown inFIG.2E, semi-circular profile, and the like. In some examples, the cross-sectional profile of channel112corresponds to the cross-sectional profile of hat portions191, e.g., both are tapered.

Referring toFIG.2A, support structure120at least partially extends within channel112and along the length of channel112. In some examples, support structure120is configured to conform to each hat portion191and to retain the cross-sectional shape of that hat portion191when pre-cured composite stringers190is supported by and processed using post-forming processing device100. It should be noted that the same support structure120is used for different types and profiles of hat portion191. Support structure120is able to conform to these different types and profiles while providing sufficient support.

In some examples, support structure120is formed from an elastic material, configured to change the shape when conforming to different types of hat portions191. Some examples of suitable elastic materials include, but are not limited to, latex, silicone (e.g., peroxide or platinum cured silicon), and other like materials. Some considerations for material selection includes weight, clean-ability, solvent resistance, stiffness, tear strength, elongation to failure, and hardness.

In some examples, support structure120is attached to base110at side walls of channel112as, e.g., is schematically shown inFIG.1A. In these examples, support surface114remains exposed and available for interfacing with flange portions196of pre-cured composite stringers190. In other words, support structure120does not interfere when flange portions196are positioned on support surface114, e.g., compressed between support surface114and cover130. These examples are schematically shown inFIGS.2A and2B.

In some examples, support structure120comprises a jamming material or a plastically deformable material. For purposes of this disclosure, a jamming material is defined as a material that is able to change its shape at one condition and to retain its shape at another condition. More specifically, support structure120is co-formed or co-shaped with one of pre-cured composite stringers190and then retains the shape of this stringer while supporting this stringer. For example, the shape of support structure120is initially different than that of pre-cured composite stringer190. It should be noted that at this stage pre-cured composite stringer190is not yet formed. Both support structure120and a composite layup are loaded into a forming device, various examples of which are described below, and the shape of support structure120is adjusted, while pre-cured composite stringer190is being formed. Hence, support structure120is co-formed or co-shaped with pre-cured composite stringer190.

This shape is retained by support structure120during various operation of post-forming processing device100while supporting this particular stringer. In some examples, the shape is retained while processing multiple stringers of the same type, e.g., the same cross-sectional shape of hat portions. When a different type of stringer is to be supported, the shape of support structure120is changed, e.g., by co-forming or shaping with that other stringer. These examples are schematically shown inFIGS.3A and3B.

Referring toFIG.3A, in some examples, support structure120comprises support flanges124extending over support surface114of base110and outside channel112. Similar to a portion of support structure120, extending into channel112and supporting hat portions191of stringer190, support flanges124are specifically shaped to support flange portions196of stringer190. In some examples, the shape of support flanges124is different from the shape of support surface114. Therefore, the same post-forming processing device100may be used for supporting stringers with different shapes of flange portions.

In some examples, support structure120is removable from base110. For example, support structure120is removed from base110to change the shape of support structure120, e.g., when support structure120is formed from a jamming material. In some examples, different types of support structure120are used with the same base110.

Cover130is configured to attach to base110, such that the corresponding one of pre-cured composite stringers190is positioned between cover130and base110while supported by post-forming processing device100. More specifically, flange portions196of pre-cured composite stringer190are positioned and, in some examples, are compressed between cover130and support surface114as, for example, is schematically shown inFIG.3C. Cover130is configured to seal against base110. Specifically, cover130comprises vacuum seal132, which engages seal receiver115.

In some examples, base110comprises pass-through116, fluidically coupled with channel112and configured to control pressure inside channel112and under support structure120. For example, pass-through116is used to maintain the pressure under support structure120to be the same as in the environment, e.g., when hat portion191of pre-cured composite stringer190is inserted into channel112and engages support structure120or, more specifically, when hat portion191pushes support structure120deeper into channel112thereby reducing the volume under support structure120.

In some examples, post-forming processing device100further comprises flexible insert140as, e.g., shown inFIG.2D. Flexible insert140is positioned with channel112and under support structure120and is used to provide additional support to hat portion191. Flexible insert140allows using support structure120that are very flexible and able to conform to a larger variation of hat portion191than, for example, when support structure120is used without flexible insert140. In some examples, flexible insert140is made from an elastomeric rubber, such as MOSITES® rubber, latex, or something similar.

Referring toFIG.2F, in some examples, post-forming processing device100comprises pass-through bladder seal180and dead end bladder seal182. It should be noted that bladder520, which is further described below with reference toFIGS.5D-E, is a tube made, e.g., from silicone, VITON®, or other like materials. In some examples, the material of bladder520is reinforced or layered. During processing, bladder520is vented to the autoclave atmosphere during cure and vented to the ambient atmosphere during any compaction/vacuum bag. As such, in some examples, one end of bladder520comprises a fitting with a vent hole. Pass-through bladder seal180, shown inFIG.2F, connects this fitting allowing bladder520to vent, when bladder520is inside post-forming processing device100. In some examples, post-forming processing device100comprises pass-through bladder seals on both ends.

Examples of Methods of Fabricating Composite Stringer

FIG.4is a process flowchart corresponding to method400of fabricating composite stringer198, see, e.g.,FIG.1B, in accordance with some examples. Composite stringer198should be differentiated from pre-cured composite stringer190, which is an intermediate structure used to form composite stringer198. As such, in some examples, pre-cured composite stringer190and composite stringer198have the same size and shape. Therefore,FIGS.1C-1Eare representative of both pre-cured composite stringer190and composite stringer198. In some examples, composite stringer198comprises a fiber reinforced composite material, which may be also referred to as a reinforced composite material. This type of material comprises one or more non-homogeneous polymer-based components and one or more non-polymeric based components (e.g., carbon-fibers). Method400is described in greater detail below with reference toFIG.4andFIGS.5A-H.

Method400comprises forming (block410) pre-cured composite stringer190, e.g., using composite layup502. This operation is performed using forming device510(shown inFIGS.5A and5B), which is different from post-forming processing device100, used in later operation (shown inFIGS.5C-5F). As noted above, post-forming processing device100increases throughput of forming device510since various later operations are performed using post-forming processing device100.

In some examples, composite layup502comprises an uncured pre-impregnated reinforcing tape or fabric, which may be referred to as a prepreg. The tape or fabric comprises fibers, such as graphite fibers, embedded within a matrix material, such as a polymer or, more specifically, an epoxy or phenolic resin. In some examples, the tape or fabric is unidirectional or woven depending on the design and the degree of reinforcement desired in the resulting composite stringer198.

During the forming operation (block410), composite layup502is positioned on forming device510as, e.g., is shown inFIG.5A. In some examples, support structure120is positioned between composite layup502and forming device510, e.g., when support structure120is co-formed together with pre-cured composite stringer190. These examples are further described below with reference to block412. Forming device510comprises forming base511with forming cavity512, which defines the shape of hat portion191of pre-cured composite stringer. Referring toFIG.5B, forming device510also comprises forming die513, which pushes a part of composite layup502into forming cavity512and against the walls of forming cavity512.

Upon completion of this operation, composite layup502is formed into pre-cured composite stringer190. Pre-cured composite stringer190comprises hat portion191, which is disposed between forming die513and the walls of forming cavity512. Pre-cured composite stringer190also comprises flange portions196, which extend outside of forming cavity512and, e.g., conform to forming surface514of forming base511. In some examples, forming die513comprises specially configured bladders, pressing on flange portions196. These bladders are pressurized and contact flange portions196prior to forming hat portion191, in some examples to different pressure level to allow composite layup502to slip on forming surface514while hat portion191is being formed.

In some examples, forming pre-cured composite stringer190on forming device comprises forming (block412) support structure120of post-forming processing device100. For example, support structure120comprises a jamming material, various examples and features of which are described above. In some examples, support structure120is shaped in a separate operation from pre-cured composite stringer190. Alternatively, support structure120and pre-cured composite stringer190are co-formed or co-shaped in the same overall operation, e.g., the operation represented by block412is a part of the operation represented by block410, as shown inFIG.4. In other words, support structure120is placed into forming device510together with composite layup502. At this stage, the shape of support structure120is different than the shape of pre-cured composite stringer190, which will be formed on and defined by forming device510. For example, support structure120has been previously used for supporting another pre-cured composite stringer, which has a different shape. During concurrent operations represented by block410and block412, pre-cured composite stringer190is formed while support structure120is also co-formed or co-shaped. This support structure forming operation (block412) may be also referred to as a shape changing operation.

In some examples, method400also comprises trimming of pre-cured composite stringer190, e.g., cutting a portion of pre-cured composite stringer190. For example, an ultrasonic knife is used for cutting.

Method400proceeds with transferring (block420) pre-cured composite stringer190from forming device510to post-forming processing device100. For instance, the transfer of pre-cured composite stringer190from forming device510to post-forming processing device100is shown inFIGS.5B-5C. Various examples of post-forming processing device100are described above. In some examples, pre-cured composite stringer190is transferred unsupported. Alternatively, pre-cured composite stringer190is transferred together with support structure120.

In some examples, the transferring operation comprises controlling pressure inside channel112of base110. For example, inserting hat portion191of pre-cured composite stringer190into channel112may cause displacing of air from channel112, e.g., through pass-through116.

In some examples, the transferring operation comprises stretching (block422) support structure120of post-forming processing device100. In these examples, support structure120is formed from an elastic material that conforms to the shape of hat portion191of pre-cured composite stringer190as hat portion is inserted into channel112. More specifically, the elastic material is configured to change the shape when conforming to each of hat portions191. As noted above, in some examples, hat portions191have different cross-sectional shapes. This stretching feature as, e.g., is shown inFIGS.2A-2B, of support structure120allows supporting pre-cured composite stringers190with different sizes of hat portions191.

In some examples, the transferring operation comprises adjusting (block424) the shape of post-forming processing device100.FIGS.6A and6Billustrate base110of post-forming processing device100, which has a pivot point, defined by first axis601. Other components of post-forming processing device100, such as support structure120, are not shown for simplicity. The pivot point allows base110to have an in-plane bending and accommodate both straight pre-cured composite stringers (in the configuration shown inFIG.6A) and pre-cured composite stringers with an in-plane bend (in the configurations shown inFIG.6B). While only one pivot point is shown inFIGS.6A and6B, one having ordinary skill in the art would understand that any number of pivot points may be present. Furthermore, in some examples, post-forming processing device100has an out-of-plane bending functionality. It should be noted that some degrees of bending, especially localized bending, of pre-cured composite stringers can be accommodated by the side of channel112within base110, without bending base110.

In some examples, method400comprises inspecting (block430) pre-cured composite stringer190. The inspection is performed while pre-cured composite stringer190is positioned on post-forming processing device100. For example, the inspection involves checking the surface of pre-cured composite stringer190for wrinkles, bubbles, foreign object debris (FOD), loose fibers, wrinkles, and shape. It should be noted that the inspection operation is performed away from forming device510and curing device540, thereby allowing other pre-cured composite stringers to be processes on these devices and increasing the overall process throughput.

Method400comprises installing (block440) bladder520on pre-cured composite stringer190as, e.g., schematically shown inFIG.5D. Bladder520is installed while pre-cured composite stringer190is positioned on post-forming processing device100. In some example, bladder520is wrapped into a bladder warp, which is later cured into the skin of the stringer when bladder520is removed. Bladder520is used during curing operation to provide support inside of pre-cured composite stringer190. In some examples, bladder520is a solid object composed of silicone, urethane, or similar materials, including any combination thereof. In some examples, bladder520is shaped to substantially correspond with pre-cured composite stringer190.

Method400comprises installing (block450) noodle530at an interface between bladder520and pre-cured composite stringer190and within the plane of support surface114of base110as, e.g., schematically shown inFIG.5E. This installing operation is performed while pre-cured composite stringer190is positioned on post-forming processing device100. Noodle530is also referred to as a radius filler.

In some examples, method400comprises compacting (block460) pre-cured composite stringer190, while pre-cured composite stringer190is positioned on post-forming processing device100. For example, the compacting operation involves sealing cover130of post-forming processing device100against base110of post-forming processing device100as, for example, is schematically shown inFIG.5F. In some examples, the compacting operation further comprises contacting at least flange portions196of pre-cured composite stringer190with cover130of post-forming processing device100.

In some examples, method400comprises staging and transporting pre-cured composite stringer190. These operations are performed while pre-cured composite stringer190is positioned on post-forming processing device100. Furthermore, post-forming processing device100is used for storing pre-cured composite stringer190, while providing support to pre-cured composite stringer190.

Method400proceeds with transferring (block490) pre-cured composite stringer190from post-forming processing device100to curing device540. For instance, the transfer of pre-cured composite stringer190from post-forming processing device100to curing device540is shown inFIG.5F-5H. In some examples, pre-cured composite stringer190is transferred together with bladder520and/or noodle530, which are installed onto pre-cured composite stringer190while pre-cured composite stringer190was positioned on post-forming processing device100.

Method400comprises curing (block492) pre-cured composite stringer190on curing device540, thereby forming composite stringer198as, for example, is schematically shown inFIGS.5H and5I. For example, pre-cured composite stringer190, shown inFIG.5H, is subjected to heat and pressure to cross-link the resin within pre-cured composite stringer190. Unlike pre-cured composite stringer190, composite stringer198, shown inFIG.5I, does not require the level of support needed for pre-cured composite stringer190. As such, post-forming processing device100is not used for composite stringer198.

In some examples, various operations of method400are repeated (decision block494) with additional pre-cured composite stringer199, e.g., one example of which is shown inFIG.1E. Specifically, additional pre-cured composite stringer199has a different design than pre-cured composite stringer190, previously processed using the same post-forming processing device100. Various different designs for pre-cured composite stringers are shown inFIGS.1C-1E. Other example designs for the pre-cure composite stringer are possible as well.

Specifically, method400comprises forming410an additional pre-cured composite stringer199on an additional forming device. Unlike post-forming processing device100, which can be universally used across a variety of different designs of pre-cured composite stringers, forming devices are dedicated tools. In some examples, support structure120is reformed or reshaped during this operation of forming additional pre-cured composite stringer199. More specifically, support structure120has a different shape when supporting additional pre-cured composite stringer199than when supporting pre-cured composite stringer190.

Method400proceeds with transferring (block420) this additional pre-cured composite stringer199from the forming device to post-forming processing device100. As noted above, additional pre-cured composite stringer199has a different design and, more specifically, a different cross-sectional profile than pre-cured composite stringer190.

In some examples, method400continues with installing an additional bladder on additional pre-cured composite stringer199, while additional pre-cured composite stringer199is positioned on post-forming processing device100. Furthermore, a noodle is installed on additional pre-cured composite stringer199, while additional pre-cured composite stringer199is positioned on post-forming processing device100. However, these operations are optional.

Method400proceeds with transferring additional pre-cured composite stringer199together with additional bladder and additional noodle from post-forming processing device100to an additional curing device and curing pre-cured composite stringer190using additional curing device, thereby forming an additional composite stringer.

FIG.7is a process flowchart of method700of supporting pre-cured composite stringer190using post-forming processing device100, in accordance with some examples of the present disclosure. Method700comprises transferring (block720) pre-cured composite stringer190to post-forming processing device100as, for example, is schematically shown inFIG.5C. Various examples of pre-cured composite stringer190are described above. For example, pre-cured composite stringer190comprises comprising hat portion191, which is supported upon the transfer of pre-cured composite stringer190to post-forming processing device100. Post-forming processing device100comprises base110, comprising channel112. Post-forming processing device100also comprises support structure120, at least partially extending within channel112and along the length of channel112.

When pre-cured composite stringer190is transferred to post-forming processing device100, support structure120conforming to hat portion191of pre-cured composite stringer190, as for, example, is schematically shown inFIG.5C. More specifically, support structure120retains the cross-sectional shape of hat portion191of pre-cured composite stringer190while pre-cured composite stringer190is positioned in post-forming processing device100. In some examples, support structure120is formed from a flexible material, providing this conformal supports. In other examples, support structure120is made from a jamming material that is reshaped together with each new pre-cured composite stringer.

In some examples, the transferring operation (block720) comprises stretching (block722) support structure120of post-forming processing device100as, for example, is schematically shown inFIGS.2A-2B. In these examples, support structure120is formed from an elastic material that conforms to the shape of hat portion191of pre-cured composite stringer190as hat portion is inserted into channel112. This stretching feature of support structure120allows supporting pre-cured composite stringers190with different sizes of hat portions191.

In some examples, the transferring operation (block720) comprises adjusting (block724) the shape of post-forming processing device100.FIGS.6A and6Billustrate base110of post-forming processing device100, which has a pivot point, defined by first axis601. Other components of post-forming processing device100, such as support structure120, are not shown for simplicity. The pivot point allows base110to have an in-plane bending and accommodate both straight pre-cured composite stringers (in the configuration shown inFIG.6A) and pre-cured composite stringers with an in-plane bend (in the configurations shown inFIG.6B). While only one pivot point is shown inFIGS.6A and6B, one having ordinary skill in the art would understand that any number of pivot points may be present. Furthermore, in some examples, post-forming processing device100has an out-of-plane bending functionality. It should be noted that some degrees of bending, especially localized bending, of pre-cured composite stringers can be accommodated by the side of channel112within base110, without bending base110.

In some examples, the transferring operation (block720) comprises positioning (block726) cover130of post-forming processing device100against base110of post-forming processing device100as, for example, is schematically shown inFIG.5F. In some examples, cover130is sealed against base110. Furthermore, in some examples, this cover positioning operation (block726) compacts at least flange portions196of pre-cured composite stringer190.

In some examples, the transferring operation (block720) comprises controlling (block728) pressure inside channel112of base110. For example, inserting hat portion191of pre-cured composite stringer190into channel112may cause displacing of air from channel112, e.g., through pass-through116.

In some examples, method700comprises storing (block730) pre-cured composite stringer190. More specifically, pre-cured composite stringer190is stored in post-forming processing device100prior to removing (block740) pre-cured composite stringer190from post-forming processing device100.

Method700proceeds with removing (block740) pre-cured composite stringer190from post-forming processing device100. For example, pre-cured composite stringer190is transferred to curing device540as, for example, is schematically shown inFIG.5H. Alternatively, pre-cured composite stringer190is transferred to other equipment, e.g., for inspection.

Method700proceeds or, more specifically repeats, (decision block794) with transferring (block720) additional pre-cured composite stringer199to post-forming processing device100as, for example, is schematically shown inFIG.5J. Additional pre-cured composite stringer199comprising additional hat portion193, such that cross-sectional shape of additional hat portion193of additional pre-cured composite stringer199, different from the cross-sectional shape of hat portion191of pre-cured composite stringer190, shown inFIG.5C. However, despite this difference in the cross-sectional shapes, support structure120of post-forming processing device100conforms to additional hat portion193of additional pre-cured composite stringer199. Furthermore, support structure120retains the cross-sectional shape of additional hat portion193of additional pre-cured composite stringer199.

Aircraft Examples

In some examples, methods and systems described above are used on aircraft and, more generally, by the aerospace industry. Specifically, these methods and systems can be used during fabrication of aircraft as well as during aircraft service and maintenance.

Accordingly, the apparatus and methods described above are applicable for aircraft manufacturing and service method900as shown inFIG.8and for aircraft902as shown inFIG.9. During pre-production, method900includes specification and design904of aircraft902and material procurement906. During production, component and subassembly manufacturing908and system integration910of aircraft902takes place. Thereafter, aircraft902goes through certification and delivery912in order to be placed in service914. While in service by a customer, aircraft902is scheduled for routine maintenance and service916, which also includes modification, reconfiguration, refurbishment, and so on.

In some examples, each of the processes of method900is 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 includes without limitation any number of aircraft manufacturers and major-system subcontractors; a third party includes without limitation any number of venders, subcontractors, and suppliers; and an operator can be an airline, leasing company, military entity, service organization, and so on.

As shown inFIG.9, aircraft902produced by method900includes airframe918with plurality of systems920, and interior922. Examples of systems920include one or more of propulsion system924, electrical system926, hydraulic system928, and environmental system930. Any number of other systems can be included. Although an aerospace example is shown, the principles of the examples described herein is applied to other industries, such as the automotive industry.

Apparatus and methods presented herein can be employed during any one or more of the stages of method900. For example, components or subassemblies corresponding to manufacturing908are fabricated or manufactured in a manner similar to components or subassemblies produced while aircraft902is in service. Also, one or more apparatus examples, method examples, or a combination thereof is utilized during manufacturing908and system integration910, for example, by substantially expediting assembly of or reducing the cost of an aircraft902. Similarly, one or more of apparatus examples, method examples, or a combination thereof is utilized while aircraft902is in service, for example and without limitation, to maintenance and service916.

Further Examples

Further, description includes examples according to following clauses:

Clause 1. A post-forming processing device for supporting pre-cured composite stringers, comprising hat portions, having cross-sections, different among the pre-cured composite stringers, the post-forming processing device comprising:a base, comprising a channel, having a channel width and a channel height, wherein:the channel width is larger than a width of the hat portions of the pre-cured composite stringers, andthe channel height is larger than heights of the hat portions of the pre-cured composite stringers;a support structure, at least partially extending within the channel and along a length of the channel and configured to conform to each of the hat portions and to retain a cross-sectional shape of each of the hat portions when a corresponding one of the pre-cured composite stringers is supported by the post-forming processing device; anda cover, configured to attach to the base, such that the corresponding one of the pre-cured composite stringers is positioned between the cover and the base while supported by the post-forming processing device.

Clause 2. The post-forming processing device of clause 1, wherein the support structure is formed from an elastic material configured to change shape when conforming to each of the hat portions.

Clause 3. The post-forming processing device of clause 2, wherein the support structure is attached to the base at side walls of the channel.

Clause 4. The post-forming processing device of any one of clauses 1-3, wherein the support structure comprises a jamming material or a plastically deformable material.

Clause 5. The post-forming processing device of clause 4, wherein the support structure is co-formed with the corresponding one of the pre-cured composite stringers.

Clause 6. The post-forming processing device of clause 4, wherein the support structure comprises support flanges extending over a support surface of the base and outside the channel.

Clause 7. The post-forming processing device of clause 4, wherein the support structure is removable from the base.

Clause 8. The post-forming processing device of any one of clause 1-7, wherein the base comprising a pass-through, fluidically coupled with the channel and configured to control pressure inside the channel.

Clause 9. The post-forming processing device of any one of clauses 1-8, further comprising a flexible insert, positioned with the channel and under the support structure.

Clause 10. The post-forming processing device of any one of clause 1-10, wherein the cover is configured to seal against the base.

Clause 11. A method of fabricating a composite stringer, the method comprising:forming a pre-cured composite stringer on a forming device, the pre-cured composite stringer comprising a hat portion;transferring the pre-cured composite stringer from the forming device to a post-forming processing device, comprising:a base, comprising a channel, anda support structure, at least partially extending within the channel and along a length of the channel and conforming to the hat portion and retaining a cross-sectional shape of the hat portion; andinstalling a bladder on the pre-cured composite stringer, while the pre-cured composite stringer is positioned on the post-forming processing device;installing a noodle at an interface between the bladder and the pre-cured composite stringer and within a plane of a support surface of the base, while the pre-cured composite stringer is positioned on the post-forming processing device;transferring the pre-cured composite stringer together with the bladder and the noodle from the post-forming processing device to a curing device; andcuring the pre-cured composite stringer on the curing device, thereby forming the composite stringer.

Clause 12. The method of clause 11, further comprising inspecting the pre-cured composite stringer, while the pre-cured composite stringer is positioned on the post-forming processing device.

Clause 13. The method of any one of clauses 11-12, further comprising compacting the pre-cured composite stringer, while the pre-cured composite stringer is positioned on the post-forming processing device.

Clause 14. The method of clause 13, wherein compacting the pre-cured composite stringer comprises sealing a cover of the post-forming processing device against the base of the post-forming processing device.

Clause 15. The method of clause 14, wherein compacting the pre-cured composite stringer further comprises contacting at least flange portions of the pre-cured composite stringer with the cover of the post-forming processing device.

Clause 16. The method of any one of any one of clauses 11-15, wherein forming the pre-cured composite stringer on the forming device comprises forming the support structure of the post-forming processing device.

Clause 17. The method of any one of clauses 11-16, wherein transferring the pre-cured composite stringer from the forming device to the post-forming processing device comprises controlling pressure inside the channel of the base.

Clause 18. The method of any one of clause 11-17, wherein transferring the pre-cured composite stringer from the forming device to the post-forming processing device comprises stretching the support structure of the post-forming processing device.

Clause 19. The method of any one of clauses 11-18, further comprising:forming an additional pre-cured composite stringer on an additional forming device;transferring the additional pre-cured composite stringer from the forming device to the post-forming processing device, wherein the additional pre-cured composite stringer has a different cross-sectional profile from the pre-cured composite stringer;installing an additional bladder on the additional pre-cured composite stringer, while the additional pre-cured composite stringer is positioned on the post-forming processing device;installing an additional noodle on the additional pre-cured composite stringer, while the additional pre-cured composite stringer is positioned on the post-forming processing device;transferring the additional pre-cured composite stringer together with the additional bladder and the additional noodle from the post-forming processing device to an additional curing device; andcuring the pre-cured composite stringer using the additional curing device, thereby forming an additional composite stringer.

Clause 20. The method of clause 19, wherein the support structure has a different shape when supporting the additional pre-cured composite stringer than when supporting the pre-cured composite stringer.

Clause 21. A method comprising:transferring a pre-cured composite stringer, comprising a hat portion, to a post-forming processing device, comprising:a base, comprising a channel, anda support structure, at least partially extending within the channel and along a length of the channel and conforming to the hat portion of the pre-cured composite stringer and retaining a cross-sectional shape of the hat portion of the pre-cured composite stringer; andremoving the pre-cured composite stringer from the post-forming processing device;
andtransferring an additional pre-cured composite stringer, comprising an additional hat portion, to the post-forming processing device, wherein the support structure of the post-forming processing device conforms to the additional hat portion of the additional pre-cured composite stringer and retains a cross-sectional shape of the additional hat portion of the additional pre-cured composite stringer, different from the cross-sectional shape of the hat portion of the pre-cured composite stringer.

Clause 22. The method of clause 21, wherein transferring the pre-cured composite stringer comprises positioning a cover of the post-forming processing device against the base of the post-forming processing device.

Clause 23. The method of any one of clauses 21-22, wherein transferring the pre-cured composite stringer to the post-forming processing device comprises controlling pressure inside the channel of the base.

Clause 24. The method of any one of clause 21-23, wherein transferring the pre-cured composite stringer to the post-forming processing device comprises stretching the support structure of the post-forming processing device.

Clause 25. The method of any one of clauses 21-24, wherein the post-forming processing device is used for storing the pre-cured composite stringer prior to removing the pre-cured composite stringer from the post-forming processing device.

Conclusion

Although the foregoing concepts have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus. Accordingly, the present examples are to be considered as illustrative and not restrictive.