Patent Grant
10814562
The disclosure relates to the field of composite parts, and in particular, to the fabrication of composite parts.
When fabricating carbon fiber parts, the application of heat necessarily results in fabrication components such as mandrels, and the composite part itself, changing shape due to thermal expansion. Some materials experience a great degree of expansion, while other materials experience negligible amounts. When fabricating composite parts, the various components are necessarily made of different materials and have different shapes. Hence, they necessarily change shape in different ways (and by different amounts) during thermal expansion and contraction. For example, a mandrel for a composite part may shrink faster than the composite part itself. This applies crushing forces to the composite part that result in internal stresses which are not desired.
Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.
Embodiments described herein provide edge dams which are placed between mandrels and composite parts, and which are designed to thermally expand in a manner that prevents the mandrel from crushing a composite part while still providing support for the composite part. This prevents internal stresses from being applied to the composite part during its formation, which enhances the overall strength of the composite part.
One embodiment is a method that includes placing a laminate onto a base of a mandrel between side walls of the mandrel, placing edge dams between the side walls and the laminate that each abut the laminate and abut one of the side walls, each edge dam having a Coefficient of Thermal Expansion (CTE) greater than a CTE of the mandrel, the CTE of the mandrel being greater than a CTE of the laminate, heating the laminate, edge dams, and mandrel. The method also includes, during the heating, thermally expanding the edge dams an amount that corresponds with a difference in thermal expansion between the laminate and the mandrel.
A further embodiment is an apparatus having a mandrel having a base as well as side walls, and a laminate placed onto the base between the side walls. The mandrel has a Coefficient of Thermal Expansion (CTE) greater than a CTE of the laminate. Edge dams are placed between the side walls and the laminate. Each edge dam abuts the laminate and abuts one of the side walls, and each edge dam has a CTE greater than the CTE of the mandrel.
A further embodiment is a method that includes compensating for a disparity in thermal expansion between a laminate having a first Coefficient of Thermal Expansion (CTE), and a mandrel having a second CTE, by placing edge dams between the mandrel and the laminate that each abut the laminate and abut the mandrel, each edge dam having a third CTE that is greater than the first CTE exhibited by the laminate and less than the second CTE exhibited by the mandrel.
Other illustrative embodiments (e.g., methods and computer-readable media relating to the foregoing embodiments) may be described below. The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.
Some embodiments of the present disclosure are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings.
The figures and the following description illustrate specific illustrative embodiments of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within the scope of the disclosure. Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the disclosure is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
In this embodiment, composite fabrication system 100 has been enhanced with edge dams 130. Edge dams 130 are inserted between laminate 110 and side walls 122 of mandrel 120 (which are located at sides 126 of mandrel 120). Without edge dams 130, mandrel 120 would expand and contract at a higher rate than laminate 110 with respect to the Y direction. This would cause unhardened resin to leak out of laminate 110 if laminate 110 remained shorter than the distance between side walls 122. Alternatively, it would cause side walls 122 to apply stresses to laminate 110 if laminate 110 was longer along the Y direction than the distance between side walls 122. Because mandrel 120 and laminate 110 expand and contract at different rates in response to changes in temperature, it is not possible to simply adjust the distance between side walls 122 to account for these issues. Mandrel 120 and laminate 110 may be heated, for example, from room temperature to seven hundred and twenty five degrees Fahrenheit (° F.) during curing, resulting in substantial changes in size.
Edge dams 130 address this problem because they each have a Coefficient of Thermal Expansion (CTE) and geometry that causes them to thermally expand and contract along the Y direction in a manner that corresponds with the difference in thermal expansion between laminate 110 and mandrel 120. Thus, regardless of the differences in thermal expansion between laminate 110 and mandrel 120, edge dams 130 continue to abut both laminate 110 and mandrel 120. Phrased another way, edge dams 130 may continuously abut both laminate 110 and mandrel 120 during heating. This ensures that laminate 110 remains structurally supported while it is being fabricated, while also ensuring that laminate 110 does not receive external stresses along the Y direction.
Illustrative details of the operation of composite fabrication system 100 will be discussed with regard to
Laminate 110 is placed (e.g., laid-up) onto base 124 of mandrel 120, between side walls 122 which are located at sides 126 of mandrel 120 (step 302). Edge dams 130 are placed between side walls 122 and laminate 110, such that each edge dam abuts one of the side walls (step 304). As discussed above, each edge dam 130 has a CTE greater than a CTE of mandrel 120, and laminate 110 has a CTE less than the CTE of mandrel 120. This means that during thermal expansion, edge dams 130 will grow faster than the rest of composite fabrication system 100. In a similar fashion, during thermal contraction, edge dams 130 will shrink faster than the rest of composite fabrication system 100.
With laminate 110 and edge dams 130 placed onto mandrel 120, composite fabrication system 100 may be moved to a suitable location (e.g., an oven or autoclave) and heated. The heating process evenly heats laminate 110, edge dams 130, and mandrel 120. For thermoplastic resins, the heating process increases a temperature of thermoplastic resin 112 to a glass transition point, and then to a melting point. Thus, thermoplastic resin 112 may flow freely within laminate 110. This heating also results in thermal expansion. In further embodiments, thermoset resins may be used instead of thermoplastic resin 112. In such embodiments, the thermoset resin may be heated to a curing temperature at which it solidifies/cures. In order to ensure that resin remains at laminate 110 during heating, edge dams 130 thermally expand by an amount that corresponds with the difference in thermal expansion (along the Y direction) between laminate 110 and mandrel 120 (step 308). In this manner, edge dams 130 continue to abut both laminate 110 and side walls 122 throughout the heating process. In a similar fashion, during cooling, the side walls 122 shrink by an amount that corresponds with the difference in thermal expansion (along the Y direction) between laminate 110 and mandrel 120. Phrased another way, the thermal expansion difference between the laminate 110 and the mandrel 120 is compensated for by edge dams 130, owing to their material and shape. This ensures that side walls 122 do not apply stresses to laminate 110 during cooling.
Maintaining contact between edge dams 130 and laminate 110 during fabrication ensures that thermoplastic resin 112 does not leak out of laminate 110 (because edge dams 130 physically block the flow of thermoplastic resin 112). At the same time, edge dams 130 ensure that side walls of mandrel 120 do not apply stresses to laminate 110 during heating or cooling, because edge dams 130 ensure that side walls 122 do not contact laminate 110 or press into laminate 110. Specifically, it is desirable to ensure that mandrel 120 does not apply compressive loads to laminate 110 during curing. This feature may be particularly desirable during the time period when laminate 110 is cooled from the melting point to the glass transition point. This ensures that laminate 110, when hardened into a composite part, is not subject to any undesired internal stresses that would have resulted from mandrel 120 having applied compressive loads during curing.
Method 300 provides a substantial advantage over prior techniques, because it utilizes edge dams 130 in a manner that ensures that stresses are not applied to a composite part during formation of that composite part, which is highly desirable.
In the following examples, additional processes, systems, and methods are described in the context of a composite fabrication system.
Mandrel 740 is disposed above laminate 710, and may apply force against laminate 710 that presses laminate 710 into a desired shape during fabrication. For example, mandrel 740 may apply force after thermoplastic resin 716 has melted, in order to conform laminate 710 into a desired shape. In further embodiments, mandrel 720 and/or mandrel 740 may be contoured.
Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of aircraft manufacturing and service in method 800 as shown in
Each of the processes of method 800 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.
As shown in
As already mentioned above, apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service described in method 800. For example, components or subassemblies corresponding to component and subassembly manufacturing 808 may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft 802 is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during component and subassembly manufacturing 808 and system integration 810, for example, by substantially expediting assembly of or reducing the cost of an aircraft 802. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft 802 is in service, for example and without limitation, to maintenance and service 816. For example, the techniques and systems described herein may be used for material procurement 806, component and subassembly manufacturing 808, system integration 810, service 814, and/or maintenance and service 816, and/or may be used for airframe 818 and/or interior 822. These techniques and systems may even be utilized for systems 820, including for example propulsion system 824, electrical system 826, hydraulic system 828, and/or environmental system 830.
In one embodiment, a part comprises a portion of airframe 818, and is manufactured during component and subassembly manufacturing 808. The part may then be assembled into an aircraft in system integration 810, and then be utilized in service 814 until wear renders the part unusable. Then, in maintenance and service 816, the part may be discarded and replaced with a newly manufactured part. Inventive components and methods may be utilized throughout component and subassembly manufacturing 808 in order to manufacture new parts.
Any of the various control elements (e.g., electrical or electronic components) shown in the figures or described herein may be implemented as hardware, a processor implementing software, a processor implementing firmware, or some combination of these. For example, an element may be implemented as dedicated hardware. Dedicated hardware elements may be referred to as “processors”, “controllers”, or some similar terminology. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, a network processor, application specific integrated circuit (ASIC) or other circuitry, field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), non-volatile storage, logic, or some other physical hardware component or module.
Also, a control element may be implemented as instructions executable by a processor or a computer to perform the functions of the element. Some examples of instructions are software, program code, and firmware. The instructions are operational when executed by the processor to direct the processor to perform the functions of the element. The instructions may be stored on storage devices that are readable by the processor. Some examples of the storage devices are digital or solid-state memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media.
Although specific embodiments are described herein, the scope of the disclosure is not limited to those specific embodiments. The scope of the disclosure is defined by the following claims and any equivalents thereof.
| Number | Name | Date | Kind |
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| 8182644 | Siegel | May 2012 | B2 |
| 20150314494 | Arnaud | Nov 2015 | A1 |
| 20170326808 | Kizhakkepat et al. | Nov 2017 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20190291352 A1 | Sep 2019 | US |
