System and method for curing composite structures

Abstract

To provide a system for curing composite structures, and a method for curing composite structures.SOLUTION: A composite curing system (100) includes a casting (156) and an expandable medium (130). The casting (156) is configured to be positioned over at least a portion of the composite structure (200) and to solidify to enclose at least said portion of the composite structure (200). The expansive medium (130) is configured to expand such that the expansive medium (130) applies positive pressure to the composite structure (200) and the casting (156).SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to composite manufacturing, and more particularly to systems and methods for curing composite structures. [Background technology]

[0002] Engineered composite materials are used in many applications, typically when the composite can be made stronger, lighter, and / or more inexpensively than traditional materials. Modern composite materials vary widely, with the most common being various fiber-reinforced polymer composites, such as glass fiber composites and carbon fiber composites. For many composite materials, the manufacturing process involves curing the composite structure, which is typically carried out under high temperatures and pressures. Industrial autoclaves are often used to cure composites because they allow for the application of both temperature and pressure under controlled conditions. However, processes requiring autoclaves can lead to bottlenecks in the manufacturing process. This is because throughput is dependent on the autoclave's capacity and requires the transport of raw materials and uncured materials to and from the autoclave, followed by the transport of the cured composite. Therefore, those skilled in the art continue to conduct research and development efforts in the field of predictive assembly. Summary of the Invention

[0003]

[0003] Disclosed are embodiments of a system for curing a composite structure, a method for curing a composite structure, and a composite workpiece. The following is a non-exclusive list of embodiments of the present disclosure, which may include those that are claimed or not claimed.

[0004] In one embodiment, a system of the present disclosure includes a casting and an expandable medium, the casting configured to be disposed over at least a portion of a composite structure and to solidify to enclose at least a portion of the composite structure, and the expandable medium configured to expand such that the expandable medium applies a positive pressure to the composite structure and the casting.

[0005] In one embodiment, the method of the present disclosure includes the steps of: (1) encasing at least a portion of a composite structure in a casting; (2) expanding an expandable medium to apply a positive pressure to the composite structure; and (3) curing the composite structure 200.

[0006] In one embodiment, a composite workpiece of the present disclosure includes a composite structure including a plurality of composite plies, at least a portion of which are uncured or partially cured, at least a portion of which is surrounded by a casting, and an expandable medium configured to expand to a predetermined volume upon a predetermined change in an attribute of the expandable medium, such that the expandable medium applies a positive pressure to the composite structure.

[0007] Other embodiments of the disclosed systems, methods, and composite workpieces will become apparent from the following detailed description, the accompanying drawings, and the claims. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic block diagram of a system for curing a composite structure. [Figure 2] 1 is a flow chart of an example method for curing a composite structure. [Figure 3] 1 is a schematic cross-sectional view of an example of a restraint container of a system applied to a composite structure. [Figure 4] 4 is a schematic cross-sectional view of the example system shown in FIG. 3 with an expandable medium disposed within the interior volume of the restraint container. [Figure 5]5 is a schematic cross-sectional view of the example system shown in FIG. 4 after the expansion medium has expanded. [Figure 6] 1 is a schematic cross-sectional view of an example system. [Figure 7] 1 is a schematic cross-sectional view of an example system. [Figure 8] 1 is a schematic cross-sectional view of an example system. [Figure 9] 1 is a schematic cross-sectional view of an example system. [Figure 10] 1 is a schematic cross-sectional view of an example system. [Figure 11] 1 is a schematic cross-sectional view of an example system. [Figure 12] FIG. 1 is a schematic perspective view of an example of an aircraft hat stiffener. [Figure 13] 1 is a schematic perspective view of an example of an aircraft wing including stiffeners; FIG. [Figure 14] 1 is a flowchart of an example method for manufacturing and entering service of an aircraft. [Figure 15] FIG. 1 is a schematic block diagram of an example aircraft. DETAILED DESCRIPTION OF THE INVENTION

[0009] By way of example, and referring generally to FIGS. 1-11 , the present disclosure relates to a system 100 and method 1000 for curing a composite structure 200. Embodiments of the system 100 and method 1000 provide an "out-of-autoclave" cure that achieves substantially the same quality composite parts as autoclaves, without the need for processing in an autoclave and without the need for large, capital-intensive equipment. The curing process enabled by the system 100 and / or method 1000 facilitates curing at a lower cost, faster speed, and with a smaller footprint. Additionally, in some embodiments, the system 100 and / or method 1000 facilitates localized or isolated curing of portions of the composite structure 200.

[0010] This disclosure recognizes that many composite parts require an autoclave to apply heat and pressure to cure (solidify) the composite. The use of an autoclave requires large amounts of floor space and high energy costs. Embodiments of the system 100 and method 1000 disclosed herein allow for the use of an expandable material, such as foam, optionally with controlled heating, to provide the pressure required for curing.

[0011] In various embodiments, a portion of a pre-cured or partially cured composite component is placed in or otherwise confined within a curing vessel. Typically, the vessel is designed to accommodate the shape and geometry of the composite component and to accommodate an intumescent material. In various embodiments, the intumescent material is disposed between the vessel and the composite component. In various embodiments, the intumescent material is activated to expand within the vessel. In various embodiments, heat is used to activate the intumescent material. In some embodiments, heat is also used to catalyze the composite curing.

[0012] Advantages of system 100 and method 1000 include eliminating and / or reducing the need for large autoclaves and improving factory layout and energy usage. Embodiments of system 100 and method 1000 also utilize an intumescent material in combination with heat to cure the composite. Repair or post-cure can also be performed without the need for re-autoclaving. Furthermore, embodiments of system 100 and method 1000 provide the option of curing and / or repairing composite parts outside of a factory or other manufacturing environment.

[0013] Next, an embodiment of a system 100 according to the present disclosure will be described with reference to FIGS. 1 and 3-10. The system 100 includes multiple elements, features, and components. Not all of the elements, features, and / or components described or illustrated in an embodiment are required for that embodiment. Some or all of the elements, features, and / or components described or illustrated in an embodiment may be combined in various ways with other embodiments, without the need to include other elements, features, and / or components described in those other embodiments, and such combinations may not be explicitly described or illustrated in the embodiments herein.

[0014] 1 is a schematic block diagram illustrating one or more examples of a system 100. As described in more detail later herein, in various embodiments, the system 100 includes multiple components, including one or more of a containment container 102, a cover 106, a base 104, a wall 112, an overlay 168, a retainer 120, a clamp 122, a robotic manipulator 124, an expandable medium 130, a rigid form 142, a molding surface 144, an intermediate layer 164, a caul 146, a barrier 162, a casting 156, an outer casting 192, an inner casting 194, an encapsulation element 154, a bladder 178, a heater 158, a bagging material 188, an expandable element 196, an actuator 108, a sensor 166, and a controller 176.

[0015] 3-10 illustrate various embodiments of a system 100 used to cure a composite structure 200. The system 100 can have a variety of overall footprints; for example, the restraint container 102 of the system 100 can have a variety of overall sizes depending on the application. In various embodiments, the footprint of the system 100, e.g., the overall operational size of the restraint container 102, is smaller than the overall size of the composite structure 200 to be cured. In such embodiments, the system 100 enables localized or independent curing of a portion 202 of the composite structure 200. Generally, the portion 202 of the composite structure 200 refers to a portion of the composite structure 200 that is to be cured (e.g., locally or independently cured). By way of example, the portion 202 may include or refer to at least one uncured portion, a partially cured portion, or a portion of the composite structure 200 that requires repair. However, in other embodiments, the footprint of the system 100, including the overall operational size of the restraint container 102, is substantially the same as or larger than the overall size of the composite structure 200 to be cured, allowing the entire composite structure 200 to be cured outside of an autoclave.

[0016] In various embodiments, system 100 is an adjustable molding system including a restraint container 102 and an expandable medium 130 (FIGS. 3-10). In some embodiments, restraint container 102 can contain the entire composite structure 200 to be cured, with the entire composite structure 200 and the expandable medium 130 located within or otherwise restrained by the restraint container 102. In other embodiments, restraint container 102 is selectively positioned relative to a portion 202 of the composite structure 200, with at least the portion 202 of the composite structure 200 and the expandable medium 130 located within or otherwise restrained by the restraint container 102. System 100 is configured to facilitate the application of positive pressure to portion 202 of the composite structure 200 by the expansion of expandable medium 130 during the process of curing portion 202 of the composite structure 200. In various embodiments, composite structure 200 is uncured, partially cured, or in need of repair. The containment container 102 and the expansion medium 130 are configured to apply a positive pressure to the composite structure 200 during the process of curing the composite structure 200 .

[0017] 1 , in various embodiments, composite structure 200 is a composite part, component, article, etc. that includes one or more composite layers 208 (also referred to as plies) that are bonded together through curing (e.g., by the application of heat and / or pressure). Composite structure 200 can include any suitable number of composite layers 208. In various embodiments, composite structure 200 includes one or more polymeric materials, thermoplastic materials, thermoset materials, fiber-reinforced materials, and / or any other suitable materials, depending on the desired properties of the finished workpiece. In one or more embodiments, at least a portion of composite layers 208 is uncured, partially cured, or a repair patch or filler material (e.g., composite patch 214). In one or more embodiments, the activation temperature 152 of the intumescent medium 130 (e.g., intumescent pellets 136) is lower than the cure temperature 212 of the composite layer 208, e.g., the cure temperature of at least the portion of the composite layer 208 that is uncured, partially cured, or formed into a repair patch (e.g., composite patch 214). In one or more embodiments, the activation temperature 152 of the intumescent medium 130 (e.g., intumescent pellets 136) is at least the cure temperature 212 of the composite layer 208, e.g., the cure temperature of at least the portion of the composite layer 208 that is uncured, partially cured, or formed into a repair patch (e.g., composite patch 214). In one or more embodiments, the activation temperature 152 of the expandable medium 130 (e.g., expandable pellets 136) is higher than the curing temperature 212 of the composite layer 208, e.g., the curing temperature of at least a portion of the composite layer 208 that is uncured, partially cured, or formed into a repair patch (e.g., composite patch 214).

[0018] 1 and 3-10 , in one or more embodiments, system 100 includes casting 156 and expandable medium 130. Casting 156 is configured to be disposed over at least a portion (e.g., portion 202) of composite structure 200. Casting 156 is configured to solidify, thereby enclosing at least the portion of composite structure 200. Expandable medium 130 is configured to expand such that expandable medium 130 applies a positive pressure to composite structure 200 and casting 156.

[0019] For purposes of this disclosure, the term "hard" refers to a solid, rigid, and / or non-expanding state. In some instances, the term "hard" includes rigid. Similarly, for purposes of this disclosure, the terms "set," "solidification," and similar terms refer to the ability of a casting or casting material to change from a flexible, moldable, pliable, flowable, conformable, and / or expansive state to a solid, rigid, and / or non-expanding state. In some instances, a casting or casting material is also rigid when solidified.

[0020] 3-5 , the casting 156 is positioned or disposed between the expandable medium 130 and the composite surface 206 of at least the cured portion 202 of the composite structure 200. In such embodiments, the casting 156, upon solidification, forms a pressure-equalizing mechanism or layer that transforms the potentially uneven pressure from the expanding expandable medium 130 into a substantially uniform pressure on the composite structure 200, thereby facilitating improved curing and surface quality and / or improved consolidation. In such embodiments, the expansion of the expandable medium 130 applies a positive pressure to the exterior of the casting 156 and to (e.g., indirectly) the composite structure 200 through (e.g., via) the casting 156.

[0021] In one or more embodiments, as shown in FIGS. 6-8 , a casting 156 is positioned or disposed over the expandable medium 130 and at least the cured portion 202 of the composite structure 200. In such embodiments, the casting 156 forms at least a portion of the containment container 102. In such embodiments, the casting 156, once solidified, serves as a space-confining container, with the hard shell of the casting acting as the vessel walls. As an example, the casting 156 may serve as the cover 106 and form the wall 112. In such embodiments, the expansion of the expandable medium 130 exerts a positive pressure within the casting 156 and (e.g., directly) on the composite structure 200.

[0022] 11 , the system 100 includes two or more layers of casting 156, such as a first or outer casting 192 and a second or inner casting 194. In one or more embodiments, the inner casting 194 is positioned or disposed between the expandable medium 130 and the composite surface 206 of at least the portion 202 of the composite structure 200 to be cured. In such embodiments, the inner casting 194, upon solidification, forms a pressure equalization mechanism or layer that transforms the potentially uneven pressure from the expanding expandable medium 130 into a substantially uniform pressure on the composite structure 200, resulting in improved cure and surface quality. In one or more embodiments, the outer casting 192 is positioned or disposed over the inner casting 194, the expandable medium 130, and at least the portion 202 of the composite structure 200 to be cured. In such embodiments, the outer casting 192 forms at least a portion of the containment container 102. In such an embodiment, once solidified, outer casting 192 acts as a space-confining container, with the shell of the solid casting acting as the vessel wall. In such an embodiment, expansion of expandable medium 130 exerts a positive pressure on the interior of outer casting 192 and (e.g., indirectly) on composite structure 200 via (e.g., through) inner casting 194.

[0023] Referring to FIG. 1 , in one or more embodiments, the casting 156 includes a casting material 182. In one or more embodiments, the casting material 182 is configured to solidify upon a predetermined change in an attribute 184 of the casting material 182. By way of example, the casting material 182 may solidify in response to a change in temperature, time, chemical composition, pressure, or other attribute of the material of the casting 156. As one example, the casting 156 is placed or formed on the portion 202 of the composite structure 200 prior to the addition of the expandable medium 130 ( FIGS. 3-5 ). As another example, the casting 156 is placed or formed on the portion 202 of the composite structure 200 and the expandable medium 130 after the addition of the expandable medium 130 ( FIGS. 6-8 ). In one or more embodiments, the casting 156 is configured to solidify prior to or during the curing process. The casting 156 can be selected to be heat resistant and easily removable after curing of the composite structure 200. Examples of casting materials 182 include, but are not limited to, plaster, cement, fiber (e.g., fiberglass) reinforced plastic, polyvinyl chloride, epoxy, rubber, thermoset or thermoplastic resins, composite materials, ceramics, and the like.

[0024] In one or more embodiments, the casting material 182 is heat-activated. In such embodiments, the predetermined change in the attribute 184 of the casting material 182 includes changing the temperature of the casting material 182 and / or changing the temperature of one or more portions of the casting material 182. Thus, causing the predetermined change in the attribute of the casting material 182 can include increasing the temperature of the casting 156 from a low temperature, such as ambient temperature (e.g., room temperature), to at least an initial temperature or a predetermined temperature above ambient temperature. (For example, the predetermined temperature can be a few degrees above ambient temperature suitable for causing the predetermined expansion of the expansile element.) The casting material 182 then solidifies or hardens as a result of this temperature increase. In such embodiments, the heat-activated casting material 182 is configured to solidify when the temperature of the casting material 182 is increased to at least the predetermined temperature. In one or more embodiments, the predetermined change in the attribute 184 of the casting material 182 is a combination of two or more properties of the casting material 182, such as a ratio or product of quantitative values ​​associated with the properties of the casting material 182. In one or more embodiments, the casting material 182 includes two materials (e.g., a binary mixture), such as a base and a curing agent (e.g., a reactant, catalyst, or accelerator) that solidify or harden through a chemical reaction when mixed together. In one or more embodiments, the casting material 182 includes a resin-based composite that solidifies or hardens in response to exposure to a specific wavelength of light (e.g., blue light in the 400-500 nm range). In one or more embodiments, the casting 156 can be solidified or accelerated to solidify using a combination of solidification techniques, such as, for example, heat and binary mixing, heat and ultraviolet (UV) curing, or other combinations. If heat is required to solidify or accelerate the solidification of the casting 156, this typically involves elevating the temperature up to the curing temperature of the composite.

[0025] In one or more embodiments, the casting material 182 is heat-reflective or includes a heat-reflective material, liner, or layer. As an example, the casting 156 can include at least one heat-reflective film as one of the layers in the cast. The heat-reflective film can be the innermost layer, a middle or interior layer, and / or the outermost layer of the cast. The heat-reflective nature of the casting 156 can facilitate facilitating heating of the expandable medium 130 during the curing process to cause expansion of the expandable medium 130.

[0026] 1 and 3-11 , in one or more embodiments, the restraint container 102 has (e.g., at least partially forms or defines) an interior volume 114 and is configured to enclose at least the portion of the composite structure 200. As shown in FIGS. 3-5 , in one or more embodiments, the restraint container 102 includes a cover 106. The cover 106 is configured to enclose a casting 156, the expandable medium 130, and at least the portion of the composite structure 200. In such an embodiment, the expandable medium 130 is disposed within the interior volume 114 between the restraint container 102 (e.g., cover 106) and the casting 156. As shown in FIGS. 6-10 , in one or more embodiments, the casting 156 forms at least a portion of the restraint container 102. The casting 156 is configured to enclose the expandable medium 130 and at least the portion of the composite structure 200. In such an embodiment, expandable medium 130 is disposed within interior volume 114 between casting 156 and composite structure 200 .

[0027] 1 and 3-5, in one or more embodiments, cover 106 forms a portion of restraint container 102, such as when composite structure 200 is supported by base 104. In such embodiments, base 104 may form at least a portion of restraint container 102. In one or more embodiments, cover 106 forms the entire restraint container 102, such as when composite structure 200 is supported by additional stiffeners or is unsupported.

[0028] In one or more embodiments, the cover 106 is selectively positioned relative to the composite structure 200 such that at least the portion 202 of the composite structure 200 and the expandable medium 130 are positioned within or otherwise constrained by the cover 106. The cover 106 is movable relative to the composite structure 200 and the base 104 to allow selection, isolation, and / or targeting of the portion 202 of the composite structure 200 to be cured. Moving the cover 106 facilitates localized curing of individual areas or portions on the composite structure 200. In one or more embodiments, the cover 106 can be completely removed from the composite structure 200, such as after curing. In such embodiments, the cover 106 includes (e.g., forms or defines) the interior volume 114 and is configured to enclose the portion 202 of the composite structure 200.

[0029] In one or more embodiments, the cover 106 has a size and / or dimensions suitable to cover the entire composite structure 200 to be cured. In such embodiments, the dimensions (e.g., length and / or width) of the cover 106 are equal to or greater than the dimensions (e.g., length and / or width) of the composite structure 200. In one or more embodiments, the cover 106 is movable and selectively positioned along the length of the composite structure 200.

[0030] In one or more embodiments, the cover 106 has a size and / or dimensions suitable to cover at least the portion 202 to be cured. In such embodiments, the dimensions (e.g., length and / or width) of the cover 106 are less than at least one of the dimensions (e.g., length and / or width) of the composite structure 200. In one or more embodiments, the cover 106 is movable and selectively positioned along the length of the composite structure 200.

[0031] 1 , the cover 106 has a cross-sectional profile 118. In one or more embodiments, the cross-sectional profile 118 of the cover 106 corresponds to the cross-sectional shape 204 of the composite structure 200. At least approximately matching the cross-sectional profile 118 of the cover 106 with the cross-sectional shape 204 of the cured portion 202 of the composite structure 200 facilitates reducing the interior volume 114 that must be filled with the expandable medium 130 upon inflation.

[0032] In one or more embodiments, the cover 106 includes a perimeter 116. In one or more embodiments, at least a portion of the perimeter 116 is configured to contact a composite surface 206 of the composite structure 200, such as in instances where the system 100 is intended for localized stiffening of the portion 202 of the composite structure 200. The contact between the perimeter 116 of the cover 106 and the composite surface 206 of the composite structure 200 facilitates containment of the expandable medium 130 disposed within the interior volume 114. In such instances, the portion 202 of the composite structure 200 is located within or restrained by the perimeter 116 of the cover 106. In one or more embodiments, at least a portion of the perimeter 116 of the cover 106 is configured to be sealed to the composite surface 206 of the composite structure 200. Sealing the periphery 116 of the cover 106 to the composite surface 206 of the composite structure 200 allows for the use of vacuum pressure (e.g., negative pressure) during the curing process and / or as a means of holding the cover 106 in place on the composite surface 206.

[0033] In various embodiments, cover 106 includes any suitable element or feature that facilitates placement of inflation medium 130 in and / or removal of inflation medium from interior volume 114. In one or more embodiments, cover 106 includes a removable or openable panel (e.g., a door) that, when positioned relative to composite structure 200, allows access to interior volume 114 and placement of inflation medium 130.

[0034] In one or more embodiments, at least a portion of the cover 106 is heat reflective. By way of example, at least one of the walls 112 of the cover 106 is heat reflective. In one or more embodiments, at least a portion of the interior surface of the cover 106 includes or is coated with a heat reflective material. The heat reflective nature of the cover 106 facilitates heating of the expandable medium 130 to cause expansion of the expandable medium 130 during the curing process.

[0035] 1 and 3-5, in one or more embodiments, the interior volume 114 of the restraint container 102 (e.g., the cover 106) is selectively variable. In one or more embodiments, selectively changing or varying the interior volume 114 facilitates a controlled reduction of the interior volume 114. Selectively reducing the interior volume 114 can correspondingly reduce the amount of inflation media 130 required to fill the interior volume 114 upon inflation. In one or more embodiments, selectively changing or varying the interior volume 114 facilitates a controlled reduction or expansion of the interior volume 114. Selectively reducing or expanding the interior volume 114 facilitates flexible control of the positive pressure provided by the inflation media 130 upon inflation.

[0036] In one or more embodiments, the cover 106 of the restraint container 102 includes a plurality of walls 112. In one or more embodiments, the walls 112 form or define at least a portion of the interior volume 114. In one or more embodiments, the walls 112 have or form the cross-sectional profile 118 of the cover 106. In such embodiments, the expandable medium 130 is disposed between the walls 112 and a casting 156, which is disposed over at least the portion 202 of the composite structure 200 to be cured.

[0037] In one or more embodiments, at least one of the walls 112 is movable relative to at least one other of the walls 112 to selectively alter the interior volume 114 of the containment container 102. In one or more embodiments, the expandable medium 130 is disposed within the interior volume 114 between at least one of the walls 112 of the cover 106 and a casting 156, the casting being located over at least a portion 202 of the composite structure 200. Selective movement of at least one of the walls 112 relative to at least one other wall 112 facilitates selective control (e.g., enlarging or contracting) of the interior volume 114 defined by the walls 112. Selective movement of at least one of the walls 112 relative to at least one other wall 112 further facilitates selective control (e.g., increasing or decreasing) of the positive pressure generated by the expandable medium 130 upon inflation.

[0038] In one or more embodiments, at least a portion of cover 106, e.g., wall 112 of cover 106, is rigid (e.g., stiff or non-flexible) and non-distensible. In such embodiments, at least a portion of cover 106, e.g., wall 112, can be formed from any suitable material, including, but not limited to, a metallic material, a composite material, a cementitious material, a ceramic material, a polymeric material, etc. In such embodiments, wall 112 restrains expandable medium 130 and resists the positive pressure generated by expandable medium 130 upon expansion. In such embodiments, wall 112 can withstand the pressure generated within containment container 102 upon expansion of expandable medium 130.

[0039] 1 , in one or more embodiments, at least one instance of the actuator 108 is configured to move at least one of the walls 112 relative to at least one other wall 112. In one or more embodiments, the system 100 includes a plurality of actuators 108 configured to move the plurality of walls 112 relative to one another. The actuators 108 can be used to selectively move at least one of the walls 112 of the cover 106 to change the interior volume 114 of the containment container 102. In such embodiments, the actuators 108 are coupled to the walls 112. Actuating the actuators 108 causes movement of the walls 112. The actuators 108 can include any suitable type of controllable actuation device, such as a mechanical actuator, a pneumatic actuator, a linear actuator, a rotary actuator, etc.

[0040] In one or more embodiments, the composite structure 200 is supported by the base 104. The cover 106 is positioned relative to the base 104 and the composite structure 200. The cover 106 encloses at least the portion of the composite structure 200 to be cured. A casting 156 is positioned over at least the portion of the composite structure 200. An expandable medium 130 is positioned (e.g., applied) within the interior volume 114 of the restraint container 102 above the casting 156. An actuator 108 moves one of the walls 112 (e.g., the top wall) relative to the other wall 112 (e.g., the side wall) toward the composite structure 200, thereby reducing the interior volume 114. During the curing process, the expandable medium 130 is activated, expanding to fill the interior volume 114 and applying a positive pressure to the composite structure 200 via the casting 156. In such an embodiment, the positive pressure generated by the expansion of expandable medium 130 is applied to composite structure 200 (eg, indirectly) via casting 156 for curing.

[0041] 1 , in one or more embodiments, sensors 166 are configured to detect or otherwise determine the pressure or force being applied to composite structure 200 during curing and / or due to the expansion of expandable medium 130. In such embodiments, controller 176 ( FIG. 1 ) receives input signals or data from sensors 166 and controls and / or maintains the desired pressure applied to composite structure 200. Sensors 166 may include any suitable type or number of pressure sensors, load sensors, or other sensor devices.

[0042] In one or more embodiments, the controller 176 includes or takes the form of a closed-loop controller or utilizes closed-loop control of the pressure within the restraint container 102 and / or the pressure applied to the composite structure 200. In one or more embodiments, the interior volume 114 may be varied in response to real-time pressure measured by the sensor 166. Closed-loop control may beneficially improve the quality of composite manufacturing and repair because the closed-loop control mechanism may compensate for multiple variables, such as material batch differences, humidity, and environmental temperature. In one or more embodiments, the controller 176 utilizes the pressure measurements from the sensor 166 to control the pressure within the restraint container 102 and / or the pressure applied to the composite structure 200 by expanding or contracting the interior volume 114, for example, by selectively altering the position of one or more of the walls 112 and / or selectively inflating or deflating the inflatable element 196 or selectively inflating or deflating the inflatable medium 130 within the interior volume 114.

[0043] In one or more embodiments, the sensor 166 is configured to detect a force or load applied by the expansion medium 130 to a movable one of the walls 112 as the expansion medium 130 expands within the interior volume 114 during the curing process. As an example, the actuator 108 moves one of the walls 112 toward the unexpanded expansion medium 130 and the composite structure 200, thereby reducing the interior volume 114 of the restraint container 102. The expansion medium 130 is activated and expands to fill the interior volume 114, thereby applying a positive pressure to the composite structure 200 and the walls 112. The sensor 166 detects the force applied by the expanded expansion medium 130 to the wall 112 and transmits the data to the controller 176. In one or more embodiments, the controller 176 includes a processor, a memory, and program code configured to process the sensor data. In one or more embodiments, the controller 176 determines the pressure within the interior volume 114 and / or the pressure to be applied to the composite structure 200 based on the sensor data. If the controller 176 determines that a lower pressure is required for proper curing, the controller 176 directs the actuators 108 to move the wall 112 away from the expandable medium 130 and the composite structure 200, thereby decreasing the pressure applied to the composite structure 200. If the controller 176 determines that a higher pressure is required for proper curing, the controller 176 directs the actuators 108 to move the wall 112 toward the expandable medium 130 and the composite structure 200, thereby increasing the pressure applied to the composite structure 200.

[0044] In other embodiments, the system 100 includes other mechanisms for preventing over-pressurization and / or regulating the pressure within the interior volume 114 of the containment container 102. As an example, the cover 106 may be fixed in place relative to the composite structure 200 and may be coupled to the base 104 by, for example, a plurality of shear pins. In such an embodiment, the shear pins may be configured to break at a predetermined pressure, thereby releasing the cover 106 and reducing the pressure.

[0045] 1 , in one or more embodiments, the cover 106 includes an overlay 168. In one or more embodiments, the overlay 168 forms or defines at least a portion of the interior volume 114. In one or more embodiments, the overlay 168 has or forms a cross-sectional profile 118 of the cover 106 that corresponds to the cross-sectional shape 204 of the composite structure 200. In such embodiments, the expandable medium 130 is disposed within the interior volume 114 defined by the overlay 168 between the overlay 168 and the casting 156 of the cover 106, with the casting being positioned over the composite structure 200.

[0046] In one or more embodiments, at least a portion of the cover 106, e.g., the overlay 168 of the cover 106, is flexible and non-distensible. The use of the overlay 168 allows the cover 106 to mold (e.g., more closely conform) to the contours of the composite structure 200 and / or the expandable medium 130 disposed between the cover 106 and the composite structure 200 prior to inflation of the expandable medium 130. In such embodiments, at least a portion of the cover 106, e.g., the overlay 168, can be formed of any suitable material, including, but not limited to, metal mesh (e.g., chainmail), ceramic mesh, polymer mesh, etc. In such embodiments, the overlay 168 restrains the expandable medium 130 and resists the positive pressure generated by the expandable medium 130 upon inflation. In such embodiments, the overlay 168 can withstand the pressure generated within the containment container 102 upon inflation of the expandable medium 130.

[0047] In one or more embodiments, at least a first portion of cover 106 is flexible and non-distensible, and at least a second portion of cover 106 is rigid and non-distensible. As one example, cover 106 can include overlay 168 and at least one wall 112. In other embodiments, at least a first portion of cover 106 is non-distensible (e.g., flexible and / or rigid), and at least a second portion of cover 106 is distensible.

[0048] 1 and 3-11 , in one or more embodiments, the base 104 is configured to support at least the portion of the composite structure 200. In one or more embodiments, the base 104 forms a portion of the restraint container 102. As one example, the composite structure 200 is positioned on or supported by the base 104. As another example, the base 104 provides or serves as structural reinforcement for at least the portion 202 of the composite structure 200 that is surrounded by the cover 106 and intended to be cured using the system 100. In one or more embodiments, the cover 106 is coupled to the base 104. In one or more embodiments, the cover 106 is movable relative to the base 104.

[0049] In one or more embodiments, the composite structure 200 is placed on the base 104 during the curing process. In order to apply an appropriate compressive force (e.g., positive pressure) to the composite structure 200 while it is within the restraint container 102, it may be necessary to provide sufficient support for at least the portion 202 of the composite structure 200 to be cured. In one or more embodiments, the base 104 provides a substantially incompressible surface that supports the underside of the composite structure 200.

[0050] In one or more embodiments, base 104 substantially resists compression when pressure is applied to at least an upper surface of base 104 (e.g., molding surface 144) that contacts the lower surface of composite structure 200. In this manner, pressure applied to an outer surface of composite structure 200 (e.g., composite surface 206) cooperates with base 104 to generate a compressive force on composite structure 200.

[0051] In one or more embodiments, the base 104 has a suitable shape that defines or corresponds to the desired cross-sectional shape 204 of the composite structure 200. In one or more embodiments, the base 104 includes a rigid mold 142. In one or more embodiments, the rigid mold 142 includes a molding surface 144. In one or more embodiments, the molding surface 144 corresponds to the cross-sectional shape 204 of the composite structure 200. As shown in FIG. 3, in one or more embodiments, the rigid mold 142 has a suitable upper molding surface 144 that can shape and / or support the three-dimensional shape of the composite structure 200. As shown in FIG. 9, in one or more embodiments, the rigid mold 142 has a planar or flat molding surface 144 that can shape and / or support the two-dimensional shape of the composite structure 200.

[0052] In one or more embodiments, the base 104 is a mold used during the layup and formation of the composite structure 200. In one or more embodiments, the base 104 is a hard mold used during a curing process, such as an initial cure in an autoclave. In one or more embodiments, the base 104 is a repair mold used during a localized curing process, such as a second out-of-autoclave cure or repair process.

[0053] 1 and 9-11 , in one or more embodiments, the retainer 120 is configured to hold the cover 106 against the composite structure 200. In one or more embodiments, the cover 106 includes or is formed by the wall 112 or the overlay 168, as shown in FIGS. 3-5 . In one or more embodiments, the cover 106 includes or is formed by a casting 156, as shown in FIGS. 6-11 . The retainer 120 includes any suitable mechanism capable of securing the cover 106 to the composite structure 200 during the curing process. In one or more embodiments, the retainer 120 is configured to couple the cover 106 and the base 104. In such embodiments, the cover 106 and the base 104 combine to form the containment container 102 in which at least the portion 202 of the composite structure 200 and the expandable medium 130 are contained during the curing process. In one or more embodiments, the retainer 120 is configured to couple to the hard mold 142 of the base 104. In one or more embodiments, the retainer 120 is configured to couple the cover 106 to the hard mold 142. In one or more embodiments, a portion of the periphery 116 of the cover 106 is configured to contact the base 104, which supports the composite structure 200.

[0054] In one or more embodiments, the retainer 120 includes at least one clamp 122. In such embodiments, the clamp 122 fastens or secures the cover 106 in place relative to the composite structure 200. In one or more embodiments, the clamp 122 fastens or secures the cover 106 to the composite structure 200. In one or more embodiments, the clamp 122 fastens or secures the cover 106 to another component (e.g., the base 104 or a secondary structure). The clamp 122 may include, for example, any suitable type of clamping or fastening device, including, but not limited to, mechanical clamps, magnetic clamps, pneumatic clamps, spring clamps, latches, pins, fasteners, weights, etc. The retainer 120 may include any number of clamps 122.

[0055] 1 , in one or more embodiments, the holder 120 includes a robotic manipulator 124. In such embodiments, the robotic manipulator 124 holds or secures the cover 106 in a predetermined position relative to the composite structure 200. In such embodiments, the cover 106 is coupled to a working end (e.g., an end effector) of the robotic manipulator 124. Under computer control, the robotic manipulator 124 selectively positions the cover 106 relative to the composite structure 200 and holds the cover 106 in the proper position for curing the portion 202 of the composite structure 200.

[0056] 6-11 , in one or more embodiments, the casting 156 has (e.g., at least partially forms or defines) the interior volume 114. In such embodiments, the casting 156 takes the form of or serves as the cover 106 of the containment container 102. The expandable medium 130 is disposed within the interior volume 114 between the casting 156 and the composite structure 200. In one or more embodiments, the retainer 120 is configured to hold the casting 156 (e.g., after solidification) in position relative to and / or against the composite structure 200. In one or more embodiments, the casting 156, upon solidification, has a cross-sectional profile 118 that corresponds to the cross-sectional shape 204 of the composite structure 200.

[0057] 1 and 9-11, in one or more embodiments, the expandable medium 130 is disposed within a containment element 154. In such embodiments, the containment element 154 contains the expandable medium 130 (e.g., expandable pellets 136), which facilitates easier handling of the expandable medium 130 and removal of the expandable medium 130 after curing is complete. In one or more embodiments, the containment element 154 is non-expandable. In one or more embodiments, the containment element 154 is expandable. The containment element 154 can take any suitable form, such as a sealing film, a sealing material layer, a bag, a bladder, or the like.

[0058] 1 and 7-11, in one or more embodiments, the system 100 includes at least one intermediate layer 164. In one or more embodiments, the intermediate layer 164 is disposed within the interior volume 114 along with the expandable medium 130, as shown in FIG. 7. In one or more embodiments, the intermediate layer 164 is disposed or located between the expandable medium 130 and the casting 156, as shown in FIGS. 7 and 8. In one or more embodiments, the intermediate layer 164 is disposed or located between the expandable medium 130 and at least a portion 202 of the composite structure 200, as shown in FIGS. 9-11. In one or more embodiments, the intermediate layer 164 includes or takes the form of a barrier 162 (e.g., a barrier film), a cowl 146 (e.g., a cowl plate or cowl sheet), a reflector 186 (e.g., a reflective layer), a heater 158 (e.g., a heat blanket), or other suitable layer of material, such as a casting 156, a bladder 178, etc. In one or more embodiments, the intermediate layer 164 is disposed prior to adding the inflation medium 130 to the interior volume 114 of the restraint container 102.

[0059] In one or more embodiments, the barrier 162 is disposed between the composite structure 200 and the expandable medium 130. In such embodiments, the barrier 162 separates the expandable medium 130 from the composite surface 206 of the composite structure 200 and / or facilitates reduced porosity and / or enhanced consolidation. In one or more embodiments, the barrier 162 is disposed between the casting 156 and the expandable medium 130. In such embodiments, the barrier 162 separates the casting 156 from the expandable medium 130 and / or facilitates reduced adhesion between the casting 156 and the expandable medium 130. The barrier 162 can be selected to be heat resistant and easily removable after the composite structure 200 has cured. Example materials for the barrier 162 include silicone-based films, polymer-based films, and / or fluorinated polymer-based films. In one or more embodiments, the barrier 162 is incorporated into a vacuum bag that contains the composite structure 200 .

[0060] In one or more embodiments, the cowl 146 is disposed between the expandable medium 130 and the composite surface 206 of the composite structure 200. In such embodiments, the cowl 146 promotes improved consolidation and surface condition of the composite structure 200. The cowl 146 can be selected to be heat resistant and easily removable after the composite structure 200 has cured. Example materials for the cowl 146 include rigid or semi-rigid materials, metallic materials, composite materials, etc.

[0061] In one or more embodiments, cowl 146 includes or is formed of multiple cowl segments, as shown in Figure 10. In such embodiments, each cowl segment is separate from the other cowl segments and is movable (e.g., misaligned or slidable) relative to adjacent cowl segments. In one or more embodiments, the ends of adjacent cowl segments overlap. The separate cowl segments of cowl 146 facilitate compaction and improved surface condition.

[0062] In one or more embodiments, the reflector 186 is a heat reflector configured to direct, such as by reflection, heat energy or heat transfer toward the expandable medium 130. In one or more embodiments, the reflector 186 is disposed between the expandable medium 130 and the casting. In one or more embodiments, the reflector 186 is disposed between the expandable medium 130 and the composite structure 200. In one or more embodiments, the reflector 186 is disposed within the expandable medium 130, for example, to separate various portions or regions of the expandable medium 130. In such embodiments, the reflector 186 facilitates facilitating heating of the expandable medium 130 during the curing process to cause expansion of the expandable medium 130. The reflector 186 can take any of a variety of suitable forms, such as a heat reflective film, a heat reflective foil, or other layer of heat reflective material.

[0063] In one or more embodiments, the bladder 178 is positioned between the expandable medium 130 and the composite surface 206 of the composite structure 200, for example, between the cowl 146 and the composite surface 206. In one or more embodiments, the bladder 178 is filled with a fluid (e.g., gas or liquid) to promote increased consolidation and improved surface condition of the composite structure 200. In one or more embodiments, the bladder 178 is configured to equalize the positive pressure applied to the composite structure 200, such that the positive pressure is more uniformly applied across the composite surface 206. The bladder 178 can be selected to be heat resistant and easily removable after the composite structure 200 has cured.

[0064] In other embodiments, the system 100 includes multiple intermediate layers 164, such as two or more of the encapsulation element 154, cowl 146, reflector 186, barrier 162, etc., or a combination thereof.

[0065] 1, 7, and 8, in one or more embodiments, bagging material 188 is disposed over the casting 156. In one or more embodiments, the bagging material 188 includes or takes the form of vacuum bagging, vacuum laminate bagging, or other sheet material that uses atmospheric pressure to clamp and hold the components of the composite workpiece assembly 250 in place beneath the bagging material 188 during the curing process.

[0066] 1 , in one or more embodiments, the expansion medium 130 is configured to expand to a predetermined volume 132 such that the expansion medium 130 applies a positive pressure when a predetermined change occurs in a property 134 of the expansion medium 130. Generally, this "predetermined volume" refers to the realizable and fillable interior volume of the interior cavity of the restraint container 102 (e.g., the interior volume 114). In various embodiments, the predetermined volume 132 is substantially the same as or slightly larger than the interior volume 114 such that, unless the interior volume 114 is altered (e.g., with the movable wall 112, the controllable expansion element 196, etc.), the expansion medium 130 applies a positive pressure to the composite structure 200 when the expansion medium 130 expands to this predetermined volume 132. Generally, the amount (e.g., volume) of unexpanded inflation medium 130 filled within the interior volume 114 of the restraint container 102 is established by testing or models that predict the pressure within the restraint volume during and after inflation.

[0067] 1 , in one or more embodiments, the inflation medium 130 is configured to expand to a predetermined volume 132 when a predetermined change occurs in a property 134 of the inflation medium 130, causing the inflation medium 130 to exert a positive pressure on the composite structure 200. In one or more embodiments, the predetermined volume 132 of the inflation medium 130 in an expanded state is greater than the interior volume 114 of the restraint container 102.

[0068] 1 and 4-11, in one or more embodiments, the expandable medium 130 includes expandable pellets 136. In one or more embodiments, the expandable pellets 136 are heat activated at an activation temperature 152. In such embodiments, the expandable pellets 136 are configured to expand when the temperature of the expandable pellets 136 is increased, for example, to at least the activation temperature 152 or above.

[0069] In one or more embodiments, any suitable number of expandable pellets 136 may be disposed within the interior volume 114 of the containment container 102, provided that the expandable pellets, when expanded, are capable of applying a positive pressure to the composite surface 206 of the composite structure 200 sufficient to consolidate and shape the curing composite structure 200. The number of expandable pellets 136 depends on the size of the interior volume 114. That is, the closer the containment container 102 fits the contours of the composite structure 200, the fewer expandable pellets 136 may be required. In various embodiments, each expandable pellet 136 may have any suitable dimensions. In one or more embodiments, the length of the expandable pellets 136 is less than about 1 centimeter. The expandable pellets 136 may be substantially uniform in size or may include pellets of different sizes.

[0070] In one or more embodiments, the activation temperature 152 of the expandable pellets 136 is lower than, at least equal to, or higher than the curing temperature 212 of the composite structure 200. In one or more embodiments, the activation temperature 152 of the expandable pellets 136 is lower than, at least equal to, or higher than the curing temperature 212 of at least some of the composite plies 208 that form the composite structure 200.

[0071] 1 , in one or more embodiments, the expandable pellets 136 include foamable pellets 138. In one or more embodiments, the expandable pellets 138 are configured to expand when heated to at least a predetermined foaming temperature. In one or more embodiments, the expandable pellets 138 include a foamable material, such as a thermoplastic material treated with a foaming agent; a gas-filled balloon; hollow microspheres; a metal; any other suitable component configured to expand when heated, or any combination thereof.

[0072] 1 and 9-11, in one or more embodiments, the expandable medium 130 includes an encapsulation element 154. In one or more embodiments, the expandable pellets 136 are disposed within and encapsulated by the encapsulation element 154. In such embodiments, the encapsulation element 154 contains the expandable medium 130 (e.g., the expandable pellets 136), which facilitates easier handling of the expandable medium 130 and removal of the expandable medium 130 after curing is complete. In one or more embodiments, the encapsulation element 154 is non-expandable. In one or more embodiments, the encapsulation element 154 is expandable.

[0073] 1 , 7 , and 8 , in one or more embodiments, the heater 158 is in thermal communication with the expandable medium 130. The heater 158 is configured to heat the expandable medium 130 to an activation temperature 152 at which the expandable medium 130 expands within the interior volume 114 and applies a positive pressure to the composite structure 200. In one or more embodiments, the heater 158 is an internal heater (e.g., a heat blanket) and is configured to be disposed within the interior volume 114 of the restraint container 102 along with the expandable medium 130. In one or more embodiments, the heater 158 is an external heater and is configured to be disposed externally of the restraint container 102. The heater 158 may take any suitable form or include any suitable heating device. In various embodiments in which the expandable medium 130 is heat-activated for expansion, at least the restraint container 102, including the cover 106, may be heated externally. Alternatively, or in addition, the system 100 may include one or more heat generating materials configured to heat the expansion medium 130 to a predetermined temperature at which the expansion medium 130 expands.

[0074] In various illustrative embodiments, the restraint container 102 includes multiple components, including a base 104 and a cover 106 (e.g., wall 112, overlay 168, casting 156). In one or more embodiments, at least a portion of the composite structure 200 (e.g., portion 202) is disposed on or supported by the base 104 or other rigid supporting reinforcement. In other embodiments, the composite structure 200 is supported by another type of structure, such as another foundation component of the composite structure 200. In one or more embodiments, the cover 106 is selectively positioned relative to the composite structure 200 to enclose the expandable medium 130 and at least the portion 202 to be cured. In one or more embodiments, the casting 156 (e.g., outer casting 192) is positioned on or over the expandable medium 130 and, upon solidification, forms the cover 106 to enclose the expandable medium 130 and at least the portion 202 to be cured. In one or more embodiments, the casting 156 (e.g., inner casting 194) is disposed on or over the composite surface 206 of at least the portion 202 of the composite structure 200. In one or more embodiments, the cover 106 is disposed on or over the composite structure 200 such that the portion 202 of the composite structure 200 is located within the interior volume 114 of the restraint container 102. The expansion medium 130 is disposed in (e.g., added to or located within) the interior volume 114 of the restraint container 102 such that the expansion medium 130 is at least proximate to the portion 202 of the composite structure 200 (e.g., uncured portion, partially cured portion, repair portion) and is located opposite the base 104 or other supporting reinforcement.

[0075] Prior to the curing process, the expansion medium 130 is in an unexpanded state (e.g., FIG. 4). In the unexpanded state, the expansion medium 130 is unexpanded, or may be referred to as an unexpanded element. During the curing process, the expansion medium 130 is expanded to an expanded state (e.g., FIG. 5). In the expanded state, the expansion medium 130 is expanded, or may be referred to as an expansion element. In the expanded state, the expansion medium 130 applies pressure to the inner surface of the restraining container 102 (e.g., the cover 106 or the outer casting 192) and / or the inner casting 194 and the composite surface 206 of at least a portion 202 of the composite structure 200 (e.g., an uncured composite workpiece). The expanded expansion medium 130 applies a positive pressure (resulting from the expansion of the expansion medium 130) to the composite structure 200 during part or all of the curing process, promoting consolidation. After the composite structure 200 has cured, the expandable medium 130 may be removed from the restraint container 102 before, at the same time as, or after the cured composite structure 200 is removed from the restraint container 102 .

[0076] For purposes of this disclosure, the terms "expandable," "expand," "expanding," and similar terms refer to the ability to expand or to have the potential or capability to increase in size and / or volume. Expansive materials or individual elements can, for example, increase in size or volume symmetrically or asymmetrically. When an expansive material is capable of symmetric expansion, the material expands to a substantially equal extent along each axis. When an expansive material exhibits asymmetric expansion, the material expands relatively more along a first axis than along another axis, or along a first axis and a second axis.

[0077] In various embodiments, using a restraint container 102 to apply pressure to an uncured composite workpiece allows for composite production without the use of an industrial autoclave. By employing a restraint container 102 that is smaller than the entire composite structure 200 (e.g., an uncured or partially cured composite structure), the footprint required for curing can be significantly reduced, the amount of intumescent medium 130 can be minimized, and individual portions of the composite structure 200 can be cured locally outside of an autoclave. By employing a restraint container 102 with a selectively controllable interior volume, for example, by selectively moving one or more of the walls 112 of the cover 106, the amount of intumescent medium 130 required for curing can be significantly reduced.

[0078] In various embodiments, the expansion medium 130 is configured to expand when a predetermined change occurs in the expansion medium 130. The predetermined change is typically a change in a physical or chemical property, or a combination thereof, and / or any other suitable property of the expansion medium 130 associated with the expansion of the expansion medium 130. Unless otherwise specified, expansion of the expansion medium 130 refers to an increase in the volume of the expansion medium 130, the surface area of ​​the expansion medium 130, and / or the spatial extent of the expansion medium 130 in one or more dimensions. As an example, the expansion medium 130 can be configured to expand when the temperature of the expansion medium 130 is increased from a low temperature, such as ambient temperature, to a predetermined elevated temperature. Thus, when curing the composite structure 200 includes increasing the temperature of the composite structure 200, the expansion medium 130 expands within the interior volume 114 during the curing process. During the curing process, the expansion medium 130 (eg, during or after expansion) exerts pressure on the uncured portions of the composite structure 200 as well as the interior of the restraint container 102 .

[0079] In various embodiments, the expansion medium 130 is selected so that, upon expansion within the interior volume 114 of the containment container 102, the expansion medium 130 exerts sufficient pressure to effectively consolidate the curing composite material. Some composite materials are sufficiently compressed and cured at pressures of less than 1 atmosphere, while other composite materials are more effectively cured at pressures of 1 atmosphere or greater. The expansion medium 130 can be selected to exert sufficient pressure to achieve pressures that previously typically required an autoclave (e.g., 1-5 atmospheres).

[0080] In various embodiments, the curing process is simplified and facilitated by adding the expandable medium 130 as a plurality of expandable pellets 136 (also referred to as expandable beads). In such embodiments, the expandable pellets 136 are configured to volumetrically expand when heated to at least a predetermined temperature. In one or more embodiments, the expandable medium 130 includes one or more different types of expandable pellets 136, each of which is configured to expand (e.g., expand to a predetermined volume) when heated to a predetermined temperature. As an example, the composition of the expandable pellets 136 can be designed to establish a desired relationship between the volume of each expandable pellet 136 and the temperature of the expandable pellet 136 as a function of time.

[0081] In various embodiments, the degree of expansion of a given type or composition of expandable medium 130 (e.g., expandable pellets 136) can be measured and recorded, as can the force generated by the expansion. The formulation can then be modified to achieve a desired degree of expansion and force. In this manner, the number and composition of expandable pellets 136 employed can be selected so that expansion of multiple expandable pellets 136 within a known volume exerts a desired pressure on the uncured composite workpiece during one or more stages of the curing process. After the composite workpiece has cured, the expanded pellets 136 can be easily removed from the restraining container 102.

[0082] In one or more embodiments, the system 100 includes additional elements configured to modify or mitigate the pressure exerted by the expansion medium 130, such as, but not limited to, one or more volume-invariant elements 172 (e.g., substantially incompressible elements) and / or one or more contractible elements 174 (e.g., fluid-filled bladders or bags) that can reduce in volume after curing to facilitate access to the composite structure 200.

[0083] In one or more embodiments, the system 100 can also include one or more inflatable elements 196 ( FIG. 1 ). In such embodiments, the inflatable element 196 is disposed within the interior volume 114 of the restraint container 102. In one or more embodiments, the inflatable element 196 is configured to selectively inflate and deflate to selectively decrease or increase the interior volume 114 of the restraint container 102 that can be filled with the inflation medium 130 upon inflation. In one or more embodiments, the inflatable element 196 can include or take the form of a sealed bladder or balloon containing some type of inflation medium (e.g., inflation medium 130). As an example, a chemical (e.g., baking soda powder) can be placed within the balloon. After heating the chemical to generate gas, the balloon expands to decrease the fillable volume of the interior volume 114 of the restraint container 102 and / or provide a positive pressure to the restraint space. In other embodiments, the inflatable element 196 is an example of the inflation medium 130.

[0084] 3-11 illustrate an embodiment of a workpiece assembly 250 including a composite workpiece 210, such as a composite structure 200, and a restraint container 102. The composite structure 200 is disposed within the restraint container 102. The restraint container 102 is configured to enclose at least a portion 202 of the composite structure 200 to be cured. In one embodiment, at least the portion 202 of the composite structure 200 to be cured is covered or otherwise surrounded by a cover 106. The cover 106 is configured to facilitate applying pressure to a composite surface 206 of the composite structure 200 by expansion of an expandable medium 130. In one or more embodiments, the composite structure 200 is disposed on a base 104 or, if desired, is supported by the cover 106 and stiffeners on a side opposite the direction of positive pressure. In one or more embodiments, a wall 112 of the cover 106 defines an interior volume 114 within the restraint container 102. In one or more embodiments, the overlay 168 of the cover 106 defines the interior volume 114 within the restraint container 102. In one or more embodiments, the casting 156 forming the cover 106 defines the interior volume 114 within the restraint container 102. In one or more embodiments, the casting 156 covers the composite structure 200.

[0085] The inflation medium 130 is disposed in (e.g., added to or located within) the interior volume 114. An appropriate amount of inflation medium 130 is used such that during and / or after inflation, the inflation medium 130 contacts the composite structure 200 (e.g., directly or indirectly via the inner casting 194) and the interior surface of the cover 106 to generate and apply a positive pressure to the composite surface 206 of the composite structure 200.

[0086] The expansion medium 130 can take any suitable form. In one or more embodiments, the expansion medium 130 is added to the restraining container 102 as pellets, beads, particles, powder, or foam, for example. Alternatively, or in addition, the expansion medium 130 is added to the restraining container 102 as solid or semi-solid discrete portions, such as a layer of expansion medium 130 that can cover the portion 202 of the composite structure 200. The layer of expansion medium 130 can be added by adding a discrete encapsulation element 154 (e.g., a pouch or bag) of pellets, beads, or other smaller portions of expansion medium 130. While FIGS. 4 and 5 depict the expansion medium 130 as a plurality of expansion pellets 136, this is a representative depiction and should not be taken as limiting the structure or configuration of the expansion medium 130. Alternatively, the expandable medium 130 is placed on the composite surface 206 of at least the portion 202 of the composite structure 200 and the casting 156 is placed on top of the expandable medium 130 .

[0087] In various embodiments, the expansion medium 130 is disposed in an unexpanded state within the interior volume 114 of the restraint container 102. As shown in Figure 5, the expansion medium 130 is expanded (e.g., increases in volume) prior to and / or during the curing process to at least partially fill the interior volume 114, such that the expansion medium 130 (in its expanded state) directly or indirectly applies a positive pressure to at least some interior surfaces of the cover 106 and the composite surfaces 206 (e.g., top and / or exterior surfaces) of the composite structure 200. The pressure exerted by the expansion medium 130 when expanded aids in compressing and consolidating the portions 202 of the composite structure 200 as it cures.

[0088] In various embodiments, the inflation medium 130 is configured to expand (to a predetermined volume and / or pressure) when a predetermined change occurs in a property 134 of the inflation medium 130 (e.g., in an uninflated state). In one or more embodiments, the inflation medium 130 is placed (e.g., inserted or added) within the interior volume 114 of the restraint container 102 in an uninflated state. The predetermined change is caused in the property 134 of the uninflated inflation medium 130 while the uninflated inflation medium 130 is within the interior volume 114. The inflation medium 130 expands in response to the caused predetermined change. The property 134 of the inflation medium 130 can be a physical and / or chemical property.

[0089] In one or more embodiments, the expansion medium 130 is configured to expand in volume upon interaction with water. By way of example, the expansion medium 130 is or includes a desiccant, which is capable of increasing in volume upon absorbing water. For example, anhydrous calcium sulfate (anhydrite) increases in volume by approximately 61% upon absorbing water to form gypsum. In such embodiments, water can be added directly to the expansion medium 130, such as by adding liquid water or water vapor to the interior of the restraint container 102. Alternatively, or additionally, water or water vapor can be generated within the restraint container 102 itself, for example, by a suitable chemical reaction.

[0090] In one or more embodiments, the predetermined change in the property 134 of the expansion medium 130 includes a change in the temperature of the expansion medium 130 and / or a change in the temperature of one or more portions of the expansion medium 130. Thus, causing the predetermined change in the property of the expansion medium 130 can include increasing the temperature of the non-expanding expansion element from a low temperature, such as an ambient temperature (e.g., room temperature), to at least an initial temperature or a predetermined temperature above the ambient temperature. (For example, the predetermined temperature may be a few degrees above the ambient temperature suitable for causing the predetermined expansion of the expansion element.) The expansion element undergoes thermal expansion as a result of this temperature increase.

[0091] In one or more embodiments, the expansion medium 130 is a heat-activated expansion element. In such embodiments, the heat-activated expansion element is configured to expand when the temperature of the expansion medium 130 is raised to at least a predetermined temperature. Alternatively, or additionally, heating the expansion medium 130 to at least a predetermined temperature causes the expansion medium 130 to expand, thereby creating a predetermined pressure on the composite structure 200. Typically, the predetermined pressure is sufficient to fully cure the composite material.

[0092] In one or more embodiments, the predetermined change that occurs in the attribute 134 of the expansion medium 130 is a combination of two or more properties of the expansion medium 130, for example, a ratio or product of quantitative values ​​related to the properties of the expansion medium 130, such as two materials with different thermal expansion coefficients.

[0093] In various embodiments, the process of curing the composite structure 200 includes causing a predetermined change in a property 134 of the expandable medium 130. In one or more embodiments, the expansion of the expandable medium 130 occurs automatically during the curing process. For example, the property 134 may be the temperature of the expandable medium 130, and heat applied to the workpiece assembly 250 during the curing process may cause a predetermined change in the temperature of the expandable medium 130. That is, heat applied to the workpiece assembly 250 during the curing process may increase the temperature of the expandable medium 130 to at least a predetermined temperature associated with a desired volume and / or a desired volumetric increase. One or more properties of the expandable medium 130 may be configured such that the temperature change experienced by the expandable medium 130 during curing of the composite structure 200 causes the expandable medium 130 to expand by a desired predetermined amount due to thermal expansion. Alternatively, or in addition, expansion of the expandable medium 130 may require additional steps beyond those required to cure the composite structure 200. By way of example, expanding the expansion medium 130 may include applying an electric field, injecting a liquid, gas, and / or other suitable material, and / or causing any other suitable change in the expansion medium 130.

[0094] In various embodiments, the expandable medium 130 is thermally expandable and includes any material that can expand when it reaches a predetermined temperature. As a specific example, the group of plastic polymers that have the ability to soften when heated are referred to as thermoplastic materials. When heated above their glass transition temperature and below their melting point, solid thermoplastic materials soften and become viscous liquids. In this state, the thermoplastic materials can be reshaped, and more specifically, can expand.

[0095] Various types of thermoplastic materials are known, including, for example, acrylic polymers, acrylonitrile butadiene styrene (ABS) polymers, nylon polymers, polylactic acid (PLA) polymers, polybenzimidazole polymers, polycarbonate polymers, polyethersulfone (PES) polymers, polyetherimide (PEI) polymers, polyethylene (PE) polymers, polyphenylene oxide (PPO) polymers, polyphenylene sulfide (PPS) polymers, polyvinyl chloride (PVC) polymers, polyvinylidene fluoride (PVDF) polymers, polytetrafluoroethylene (PTFE) polymers, etc. In particular, an expandable medium 130 comprising acrylonitrile butadiene styrene (ABS) polymers can exhibit advantageous physical properties when used in combination with the embodiments described herein.

[0096] In one or more embodiments, the expandable medium 130 (e.g., expandable pellets 136) can further include a blowing agent. The blowing agent is selected so that, when heated to at least a predetermined temperature, it forms holes, pockets, or voids within the material of the expandable medium 130, thereby increasing the volume of the expandable medium 130. By way of example, a suitable blowing agent can be an inert gas impregnated into the expandable medium 130 under pressure. Such a blowing agent can be configured to expand at multiple locations within the expandable medium 130 as the temperature of the expandable medium 130 increases from an ambient or initial temperature to a predetermined elevated temperature, with the expanding gas forming holes, pockets, or voids within the pellets. The blowing agent can be added to the expandable medium 130 prior to heating.

[0097] In embodiments in which the expansion medium 130 includes a blowing agent, the blowing agent can be any suitable substance capable of producing the desired degree of expansion. The blowing agent can include physical blowing agents such as chlorofluorocarbons, hydrochlorofluorocarbons, hydrocarbons, liquid CO2, etc. Alternatively, or in addition, the blowing agent can include chemical blowing agents selected to react with one or more components of the expansion medium 130, such as isocyanates and water for polyurethanes, azodicarbonamide for vinyls, hydrazine and other nitrogen-based materials for thermoplastic and elastomeric foams, and sodium bicarbonate for thermoplastic foams.

[0098] In embodiments in which the expandable medium 130 includes a foaming agent, the foaming agent may include a foaming agent. In such embodiments, the foaming agent may be selected to generate gas, and the foaming agent may be a material that promotes foam formation, such as a surfactant. Suitable foaming agents may include sodium laureth sulfate, sodium lauryl ether sulfate (SLES), sodium lauryl sulfate (also known as sodium dodecyl sulfate or SDS), ammonium lauryl sulfate (ALS), and the like.

[0099] During the process of curing the composite structure 200, the expandable medium 130 (e.g., expandable pellets 136) expands from an unexpanded state ( FIG. 4 ) to an expanded state ( FIG. 5 ). In one or more embodiments, the expandable pellets 136 are configured to expand in response to heat applied to the workpiece assembly 250 during curing. The expandable pellets 136 expand to fill the interior volume 114 of the cover 106, causing the expanded expandable pellets 136 to apply a positive pressure to the composite structure 200, causing the composite structure 200 to cure.

[0100] In one or more embodiments, the expandable medium 130 (e.g., expandable pellets 136) is configured (e.g., formulated) to be at least partially deformable after, during, and / or before expansion. Having some degree of deformability allows the expandable medium 130 to fill small gaps that may exist, for example, between the pellets, between the pellets and the inner surface of the cover 106, and / or between the pellets and the composite surface 206 of the composite structure 200. By filling such gaps, the expandable medium 130 can provide the composite structure 200 with a substantially smooth surface.

[0101] In various embodiments, after the portion 202 of the composite structure 200 has cured, the cover 106 can be unsealed, opened, or removed, as needed, to remove the expansion medium 130. While the expansion medium 130 is generally easily removed after the composite structure 200 has cured, in some cases the expansion medium 130 remains expanded and densely packed after the composite structure 200 has cured and cooled, which tends to hinder removal. In such cases, the expansion medium 130 can be further configured in one or more ways to be more easily separated from the composite structure 200, the base 104, and / or the cover 106. As an example, the expansion pellets 136 can be configured to change shape and / or size as desired, thereby making them easier to remove. For example, the expansion pellets 136 can be configured to contract upon cooling, which causes the expansion pellets 136 to shrink within the interior volume 114 after the composite structure 200 has cured and cooled, facilitating their removal.

[0102] In one or more embodiments, the expandable medium 130 is modified to minimize sintering (self-adhesion) upon heating and expansion. Alternatively, or in addition, the expandable medium 130 is configured to minimize adhesion to surfaces, such as by coating the expandable pellets 136 with a suitable agent configured to prevent adhesion and / or promote separation.

[0103] In one or more embodiments, suitable agents for addition to the expandable medium 130 include lubricants. As an example, a lubricant can be added to the expandable pellets 136 before and / or after volumetric expansion to inhibit adhesion between the expandable pellets 136. A suitable lubricant does not interfere with the hardening of the composite structure 200 and prevents the expanded pellets 136 from substantially adhering to each other, to the containment container 102, or to components of the workpiece assembly 250. Suitable lubricants can include liquids, powders, or combinations thereof. If added as a powder, suitable lubricants can include nanopowder. Alternatively, or in addition, suitable lubricants can include silicon-based materials, fluorinated polymers, or other substantially inert substances. For example, suitable lubricants can include polytetrafluoroethylene (PTFE) powder, PTFE nanopowder, silicone, perfluoropolyether (PFPE), perfluoroalkyl ether (PFAE), perfluoropolyalkyl ether (PFPAE), etc. Such a lubricant may be added to the expandable pellets 136 prior to placing the expandable pellets 136 in the containment container 102. Alternatively, or in addition, a suitable lubricant may be added to the expandable pellets 136 while they are disposed within the containment container 102. Coating at least some of the expandable pellets 136 with a suitable lubricant may include mixing the lubricant with the plurality of pellets and / or pouring the lubricant over the plurality of pellets. Additionally, or alternatively, at least some of the plurality of expandable pellets 136 may be coated with a desired lubricant and then mixed with the plurality of uncoated pellets.

[0104] In one or more embodiments, the crystallinity and / or semi-crystallinity along the outer surface of the expandable pellets 136 can help prevent the pellets from sintering together. In one or more embodiments, at least some of the expandable pellets 136 are configured, such as by pre-processing, to have crystalline regions along their outer surface, and thus adding the expandable medium 130 includes adding a plurality of expandable pellets 136 having surface regions of increased crystallinity to reduce adhesion between the pellets, before and / or after volumetric expansion of the expandable pellets 136. In one or more embodiments, expandable pellets 136 can be employed where the outer surface of the pellet exhibits a high degree of crystallinity (e.g., where a high percentage of the volume of each pellet near its outer surface is crystalline). Crystallinity can be induced in the expandable pellets 136 by controlling one or more factors, including the material composition of the pellets, the manufacturing temperature to which the pellets are heated during manufacturing, the time the temperature of the pellets is maintained at the manufacturing temperature during manufacturing, the electric and / or magnetic fields applied during manufacturing, the distribution of the blowing agent in the pellets, the composition and / or concentration of the blowing agent, etc. The exterior surface of the expandable pellets 136 can be crystalline before, during, and / or after expansion.

[0105] 2 illustrates one or more embodiments of method 1000. An embodiment of method 1000 according to the present disclosure is described below. Method 1000 includes multiple elements, steps, operations, or processes. Not all of the elements, steps, operations, or processes described or illustrated in an embodiment are required for that embodiment. Some or all of the elements, steps, operations, or processes described or illustrated in an embodiment can be combined in various ways with other embodiments without including other elements, steps, operations, or processes described in those other embodiments, even if not explicitly described or illustrated by the embodiment herein.

[0106] 1 and 3-11, and particularly FIG. 2, in various embodiments, method 1000 includes multiple steps, as described in more detail later herein. In one or more embodiments, method 1000 is performed using system 100 (FIG. 1).

[0107] In one or more embodiments, according to method 1000, composite structure 200 includes a plurality of composite plies 208. In one or more embodiments, at least a portion of composite plies 208 are uncured. In one or more embodiments, at least a portion of composite plies 208 are partially cured. In one or more embodiments, at least a portion of composite plies 208 are in need of repair or are in the form of a repair patch (e.g., composite patch 214). In one or more embodiments, at least one of composite plies 208 is a composite patch 214 configured to repair a portion of composite surface 206 of composite structure 200.

[0108] In one or more embodiments, at least one of the composite layers 208 is a composite patch 214 configured to repair a portion of the composite surface 206 of the composite structure 200 .

[0109] In one or more embodiments, the method 1000 includes supporting 1002 at least the portion of the composite structure 200 on the base 104 of the restraint container 102. In one or more embodiments, at least the portion 202 of the composite structure 200 to be cured is supported by the base 104 such that the base 104 reinforces the composite structure 200 during the curing process.

[0110] In one or more embodiments, the method 1000 includes a step 1004 of placing a casting 156. In one or more embodiments, the casting 156 is placed or disposed between the expandable medium 130 and the composite surface 206 of the composite structure 200. The method 1000 includes a step 1006 of solidifying the casting 156. In such embodiments, the casting 156 is disposed on the composite surface 206 of at least the portion 202 of the composite structure 200. The solidifying step 1006 occurs upon or as a result of a predetermined change in the attribute 184 of the casting material 182.

[0111] In one or more embodiments, a casting 156 (e.g., inner casting 194) is disposed on or over the composite structure 200 and, upon solidification, is located between the composite surface 206 of the composite structure 200 and the expandable medium 130. In one or more embodiments, a casting 156 (e.g., outer casting 192) is disposed on or over the expandable medium 130 and, upon solidification, serves as a cover 106, overlying or enclosing the expandable medium 130 and at least a portion 202 of the composite structure 200.

[0112] In one or more embodiments, the method 1000 includes moving 1008 the cover 106 relative to the composite structure 200. In one or more embodiments, the cover 106 is moved into position to cover and enclose at least the portion 202 of the composite structure to be cured using the system 100.

[0113] In one or more embodiments, the method 1000 includes enclosing 1010 at least the portion 202 of the composite structure 200 to be cured in the restraint container 102. As an example, a cover 106 (e.g., wall 112 or overlay 168) is positioned over the composite structure 200 such that at least the portion 202 of the composite structure 200 is contained within the interior volume 114 of the restraint container 102. In one or more embodiments, the enclosing 1010 includes enclosing 1010 at least the portion 202 of the composite structure 200 in a casting 156. As an example, a cover 106 (e.g., outer casting 192) is positioned over the composite workpiece 210 such that the expandable medium 130 and at least the portion 202 of the composite structure 200 are contained within the interior volume 114 of the restraint container 102.

[0114] In one or more embodiments, according to method 1000, encasing 1010 at least portion 202 of composite structure 200 includes encasing at least portion 202 of composite structure 200 in casting 156. In such embodiments, encasing composite structure 200 in casting 156 includes disposing casting material 182 and solidifying casting material 182. Solidifying occurs upon or as a result of a predetermined change in attribute 184 of casting material 182.

[0115] In one or more embodiments, the method 1000 includes the step 1012 of holding the cover 106 against the composite structure 200. In one or more embodiments, the cover 106 is held against the composite structure 200 using a retainer. In one or more embodiments, the cover 106 is formed by the wall 112. In one or more embodiments, the cover 106 is formed by the overlay 168. In one or more embodiments, the cover 106 is formed by the casting 156 (e.g., the outer casting 192).

[0116] In one or more embodiments, the method 1000 includes the step 1014 of coupling the cover 106 to the base 104. In one or more embodiments, the cover 106 and the base 104 are coupled using a retainer 120.

[0117] In one or more embodiments, the method 1000 includes a step 1016 of adding the inflation medium 130. In one or more embodiments, the inflation medium 130 is added within the interior volume 114 of the rigid, non-inflatable cover 106 (e.g., formed by the wall 112). In one or more embodiments, the cover 106 is flexible and non-inflatable (e.g., formed by the overlay 168) and is placed or rested on the inflation medium 130 such that the inflation medium 130 is located within the interior volume 114 of the cover 106. In one or more embodiments, the casting 156 is placed on the inflation medium 130 and allowed to solidify on the inflation medium such that the inflation medium 130 is located within the interior volume 114 of the cover 106. In one or more embodiments, the adding step 1016 occurs before the encapsulating step 1010. In one or more embodiments, the adding step 1016 occurs after the encapsulating step 1010.

[0118] In one or more embodiments, the method 1000 includes selectively altering 1018 the interior volume 114 defined by the restraint container 102 and the composite structure 200. In one or more embodiments, the interior volume 114 is selectively altered by moving at least one of the walls 112 of the cover 106. As one example, selectively altering 1018 the interior volume 114 of the restraint container 102 includes moving at least one of the walls 112 relative to at least another one of the walls 112.

[0119] In one or more embodiments, the method 1000 includes altering 1020 an attribute 134 of the expansion medium 130 to expand the expansion medium 130 to a predetermined volume 132. In one or more embodiments, the method 1000, e.g., altering 1020 an attribute 134 of the expansion medium 130, includes raising the temperature of the expansion medium 130 to at least the activation temperature 152.

[0120] In one or more embodiments, the method 1000 includes the step of inflating 1022 the expandable medium 130 disposed within the interior volume 114. In one or more embodiments, the interior volume 114 is defined by the cover 106 (e.g., the wall 112, the overlay 168, or the outer casting 192) and the composite structure 200. In one or more embodiments, the interior volume 114 is defined by the cover 106 (e.g., the wall 112, the overlay 168, or the outer casting 192), the composite structure 200, and the base 104.

[0121] In one or more embodiments, the method 1000 includes the step 1024 of applying a positive pressure to the composite structure 200. As the expandable medium 130 expands, it fills the interior volume 114 and applies a positive pressure to the composite structure 200 and the cover 106. In one or more embodiments, the positive pressure is applied to (e.g., between) the casting 156 (e.g., inner casting 194) and the containment container 102, thereby indirectly applying pressure to the composite structure 200 via the casting 156 (e.g., inner casting 194). In one or more embodiments, the positive pressure is applied to the casting 156 (e.g., outer casting 192) and the composite structure 200, thereby directly applying pressure to the composite structure 200.

[0122] In one or more embodiments, the method 1000 includes detecting 1026 the pressure and / or force being applied to the composite structure 200 by the expansion of the expandable medium 130. In one or more embodiments, the pressure and / or force is detected using a sensor 166. In one or more embodiments, the method 1000 includes selectively controlling 1028 the pressure and / or force being applied to the composite structure 200.

[0123] In one or more embodiments, the method 1000 includes a step 1030 of curing at least the portion 202 of the composite structure 200. The composite structure 200 is cured by the application of pressure due to the expansion of the expandable medium 130 within the interior volume 114. In one or more embodiments, the composite structure 200 is also cured by the application of heat.

[0124] In one or more embodiments, the method 1000 includes removing 1032 the expansion medium 130. In one or more embodiments, the method 1000 includes removing 1034 the cover 106 and other components of the restraint container 102. In one or more embodiments, removing the cover 106 includes removing the casting 156 (e.g., the inner casting 194 and / or the outer casting 192).

[0125] Referring again to FIG. 1 , an example of a composite workpiece 210 according to the present disclosure will now be described. The composite workpiece 210 includes a number of elements, features, and components. Not all of the elements, features, and / or components described or illustrated in one example are required for that example. Some or all of the elements, features, and / or components described or illustrated in one example can be combined in various ways with other examples without including other elements, features, and / or components described in those other examples, even if not explicitly described or illustrated by the example herein.

[0126] In one or more embodiments, the composite workpiece 210 includes a composite structure 200 including multiple composite layers 208. At least a portion 202 (e.g., at least one of the composite layers 208) is uncured, partially cured, or in need of repair. At least the portion 202 of the composite structure 200 is surrounded by a casting 156 (e.g., an inner casting 194, an outer casting 192, or both the inner casting 194 and the outer casting 192). The expandable medium 130 is configured to expand to a predetermined volume 132 when a predetermined change in a property 134 of the expandable medium 130 occurs, causing the expandable medium 130 to apply a positive pressure to the composite structure 200.

[0127] In one or more embodiments, at least one of the composite layers 208 is a composite patch 214. The composite patch 214 is configured to repair a portion of the composite surface 206 of the composite structure 200.

[0128] In one or more embodiments, the expandable medium 130 includes expandable pellets 136. The expandable pellets 136 are heat activated at an activation temperature 152. The activation temperature 152 of the expandable pellets 136 is lower than, at least equal to, or higher than the curing temperature 212 of the composite layer 208, such as the curing temperature 212 of at least the uncured or partially cured portions of the composite layer 208.

[0129] In various other embodiments of the composite workpiece 210, the system 100 includes any one or more of the components described herein and / or illustrated in FIGS. 1 and 3-11.

[0130] Embodiments of the disclosed system 100 and method 1000 are useful for a variety of composite materials and for producing desired parts for any suitable industrial application. The system 100 and method embodiments described herein are particularly useful for out-of-autoclave production of composites, such as may be desired in a manufacturing environment or at a remote work site. The system 100 and method 1000 embodiments described herein are also useful for producing parts with unique or complex shapes that cannot be easily processed in an industrial autoclave.

[0131] 14 and 15, embodiments of the system 100 and method 1000 described herein may be associated with or used in association with an aerospace manufacturing and service method 1100, as illustrated in the flowchart of Figure 14, and an aircraft 1200, as illustrated generally in Figure 15. By way of example, the aircraft 1200 and / or the manufacturing and service method 1100 may include or utilize composite parts cured or repaired using the system 100 and / or according to the method 1000.

[0132] Embodiments of the system 100 and method 1000 disclosed herein may be used to manufacture any desired composite material in any suitable industry. Although the embodiments presented herein are described in the context of aircraft manufacturing and service, these are merely examples and should not be construed as limiting the applicability of the disclosed systems and methods.

[0133] Referring to FIG. 15 , an example of an aircraft 1200 is shown. The aircraft 1200 may be any aerospace vehicle or platform. In one or more embodiments, the aircraft 1200 includes an airframe 1202 having an interior 1206. The aircraft 1200 includes multiple onboard systems 1204 (e.g., high-level systems). Examples of the onboard systems 1204 of the aircraft 1200 include a propulsion system 1208, a hydraulic system 1212, an electrical system 1210, and an environmental system 1214. In other examples, the onboard systems 1204 also include one or more control systems coupled to the airframe 1202 of the aircraft 1200. In still other examples, the onboard systems 1204 also include one or more other systems, such as, but not limited to, a communications system, an avionics system, a software distribution system, a network communications system, a passenger information / entertainment system, a guidance system, a radar system, a weapons system, etc. Each system may include various subsystems such as controllers, processors, actuators, effectors, motors, generators, etc. depending on the functionality involved.

[0134] Aircraft 1200 may have any number of composite structures, at least a portion of which may be locally stiffened using system 100 and / or according to method 1000. Any component or substructure of an aircraft suitable for composite manufacturing may be adapted for the exemplary methods and processes described herein, including, but not limited to, structural components, fuselage panels, bulkhead sections, etc. As an example, system 100 and method 1000 described herein are particularly useful for manufacturing and / or repairing stiffeners or stringers used in aircraft manufacturing.

[0135] 12 and 13 , in one or more embodiments, aircraft 1200 includes one or more stiffeners 220 configured to support a load. In some embodiments, stiffeners 220 are attached to skin 222 to improve the strength, stiffness, and / or buckling resistance of skin 222. Stiffeners 220 may be included in any suitable portion of the frame of the aircraft (e.g., airframe frame 1202) and / or any other suitable portion of aircraft 1200. FIG. 13 illustrates stiffeners 220 stiffening skin 222 in an example embodiment of a wing 224 of aircraft 1200.

[0136] FIG. 12 illustrates an example composite structure 200 in the form of a composite hat stiffener (e.g., stiffener 220). In one or more embodiments, stiffener 220 includes a cap portion 232 and a first sidewall 234 and a second sidewall 236 extending from opposite sides of cap portion 232. In an exemplary embodiment, first sidewall 234 and second sidewall 236 extend from cap portion 232 at an obtuse angle. In other embodiments, first sidewall 234 and second sidewall 236 can form an acute angle or a substantially right angle with cap portion 232. The angle between cap portion 232 and first sidewall 234 may or may not be equal to the angle between cap portion 232 and second sidewall 236. Cap portion 232 may be substantially planar or may include curved and / or angled portions. The stiffener 220 further includes a first flange 238 extending from the first sidewall 234 and a second flange 242 extending from the second sidewall 236. The first flange 238 and the second flange 242 extend in opposite directions away from each other and may be parallel to the cap portion 232. (For example, the first flange and the second flange may be coplanar and define a plane generally parallel to a plane defined by the cap.) The first flange 238 and the second flange 242 each have a bottom surface attachable to the skin 222 such that the stiffener 220 is configured to reinforce, stiffen, and strengthen the skin 222. Multiple stiffeners 220 may be attached to a wide portion of the skin 222.

[0137] 13 illustrates an example composite structure 200 in the form of an aircraft wing (e.g., wing 224). In various embodiments, stiffener 220 is attached to skin 222 by holding stiffener 220 and skin 222 together while curing, or by curing stiffener 220 and skin 222 separately and then fastening stiffener 220 to skin 222. In various embodiments, stiffener 220 and skin 222 may each comprise one or more polymeric materials, thermoplastic materials, thermoset materials, and / or any other suitable materials, depending on the properties desired for the finished workpiece.

[0138] For example, composite stiffeners or stringers are often placed in fuselage sections and wing skins to provide stiffness and strength to the aircraft panels to which they are attached while limiting weight. Stiffeners may have concave cross-sections with protruding extensions to increase strength and rigidity. Stiffeners may also incorporate an overall curvature to match the curvature of the fuselage to which they are attached. Furthermore, stiffeners may include one or more bends or joggles to accommodate one or more aircraft systems. Due to these constraints, stiffeners may have sizes and shapes that make them difficult to transport to and from industrial autoclaves, or autoclaves may not even be able to accommodate uncured stiffeners. However, such composite stiffeners can be easily accommodated by a restraint container 102 specifically sized and shaped for that stiffener or localized portion of the stiffener. A composite stiffener that is uncured, partially cured, or to be repaired can be placed on a rigid mold (e.g., base 104) configured to define and incorporate the stiffener's desired cross-sectional profile, desired curvature, and desired joggle. The composite stiffener can then be easily cured while positioned on the rigid mold while a suitable inflatable element (e.g., inflatable medium 130) applies the necessary pressure to the composite. Similarly, areas on composite panels forming the fuselage and / or wing may also require repair. In such cases, the repairs are difficult to accommodate using an autoclave. However, such composite panels can be easily contained by a restraining container 102 that can be easily moved to cure the repaired areas of the fuselage or wing.

[0139] 14 , prior to the start of production of the aircraft 1200, production and service method 1100 includes specification and design 1102 of the aircraft 1200 and material procurement 1104. During production of the aircraft 1200, component and subassembly manufacturing 1106 and system integration 1108 of the aircraft 1200 occur. The aircraft 1200 then undergoes certification and delivery 1110 and enters service 1112. Routine maintenance and service 1114 includes upgrading, reconfiguring, modifying, etc., one or more systems of the aircraft 1200.

[0140] 14 may be performed or implemented by a system integrator, a third party, and / or an operator (e.g., a customer). A system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors. A third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers. An operator may include, but is not limited to, an airline, a leasing company, a military entity, a service organization, etc.

[0141] Embodiments of the system 100 and method 1000 shown and described herein may be employed during any one or more steps of the manufacturing and service method 1100 illustrated in the flowchart of Figure 10. In one example, at least a portion of a composite structure may be locally cured using the system 100 and / or according to the method 1000 during part and subassembly manufacturing 1106 and / or as part of system integration 1108. Additionally, at least a portion of a composite structure may be locally cured using the system 100 and / or according to the method 1000 while the aircraft 1200 is in service 1112. Additionally, at least a portion of a composite structure may be locally cured using the system 100 and / or according to the method 1000 during system integration 1108 and certification and delivery 1110. Similarly, at least a portion of the composite structure may be locally cured using system 100 and / or according to method 1000 while the aircraft 1200 is in service 1112 and during maintenance and service 1114 .

[0142] The foregoing detailed description refers to the accompanying drawings, which illustrate specific embodiments described in the present disclosure. Other embodiments having different structures and operations do not depart from the scope of the present disclosure. Like reference numerals may refer to the same feature, element, or component in different drawings. Throughout this disclosure, any one of multiple elements may be referred to individually, and multiple elements may be referred to collectively and designated by like reference numerals. Furthermore, in this specification, a feature, element, component, or step referred to in the singular does not exclude the plural features, elements, components, or steps, unless expressly stated otherwise.

[0143] Illustrative, non-exhaustive examples of the subject matter of the present disclosure are provided above, including those claimed and those not claimed. As used herein, the term "example" means that one or more features, structures, elements, components, features, and / or operational steps described in connection with that example are included in at least one aspect, embodiment, and / or implementation of the subject matter of the present disclosure. Thus, terms such as "one example," "another example," "one or more examples," and similar terms in this disclosure may, but do not necessarily, refer to the same example. Furthermore, features characterizing one example may, but do not necessarily, include features characterizing any other example. Furthermore, features characterizing one example may, but do not necessarily, be combined with features characterizing any other example.

[0144] As used herein, a system, apparatus, device, structure, article, element, component, or hardware that is "configured" to perform a particular function refers to one that can perform that particular function without any modification, and not one that could perform that particular function with any modification. That is, a system, apparatus, device, structure, article, element, component, or hardware that is "configured" to perform a particular function refers to one that is specifically selected, made, implemented, used, programmed, and / or designed to perform that particular function. As used herein, "configured" refers to characteristics that a system, apparatus, structure, article, element, component, or hardware already possesses that enable the system, apparatus, structure, article, element, component, or hardware to perform that particular function without any modification. In this disclosure, a system, apparatus, device, structure, article, element, component, or hardware that is described as "configured" to perform a particular function may also or instead be described as being "adapted" and / or "operable" to perform that function.

[0145] Unless otherwise indicated, the terms "first," "second," "third," etc. are used herein merely as labels and do not impose any order, position, or hierarchy requirements on the elements to which they refer. Furthermore, a reference to, for example, a "second" element does not require or exclude the presence of, for example, a "first" element or a lower ordinal element, and / or a "third" or higher ordinal element.

[0146] As used herein, the phrase "at least one" in reference to a list of elements means that one or more of the listed elements may be used in various combinations, or that only one of the listed elements may be required. For example, "at least one of element A, element B, and element C" includes, but is not limited to, element A, element A and element B. This example also includes elements A, element B, and element C, or elements B and element C. In other examples, "at least one" may mean, but is not limited to, two elements A, one element B, and ten elements C, or four elements B and seven elements C, or other suitable combinations. As used herein, the phrase "and / or" and the symbol " / " include any and all combinations of one or more of the associated listed elements.

[0147] As used herein, the terms "coupled," "couple," and the like refer to two or more elements being joined, linked, fastened, attached, connected, in communication, or otherwise associated (e.g., mechanically, electrically, fluidly, optically, electromagnetically) with one another. In various embodiments, these elements may be directly or indirectly associated. As an example, element A may be directly associated with element B. As another example, element A may be indirectly associated with element B, e.g., through another element C. It should be noted that not all associations between the various elements of this disclosure are necessarily shown. Thus, other connections may exist than those shown.

[0148] As used herein, the term "approximately" refers to a state that is not exactly the same as the described state, but is close to the described state and is capable of performing a desired function or achieving a desired result. As an example, the term "approximately" refers to a state that is within an acceptable range of a predetermined tolerance or precision, for example, within 10% of the described state. However, the term "approximately" does not exclude a state that is exactly the same as the described state. Additionally, as used herein, the term "substantially" refers to a state that is essentially the same as the described state and is capable of performing a desired function or achieving a desired result.

[0149] The figures 1, 3-11, and 15 referenced in the foregoing description depict functional elements, features, or components thereof and do not necessarily imply a particular, specific structure. Accordingly, modifications, additions, and / or omissions may be made to the depicted structures. Furthermore, those skilled in the art will recognize that not all elements, features, and / or components shown and described in Figures 1, 3-11, and 15 need be present in every embodiment, and not all elements, features, and / or components described herein may be present in each illustrated embodiment. Accordingly, some of the elements, features, and / or components shown and described in Figures 1, 3-11, and 15 may be combined in various ways without including other features shown in Figures 1, 3-11, and 15, other figures, and / or the accompanying disclosure, without such combinations being explicitly set forth herein. Similarly, additional features not limited to the illustrated embodiments may be combined with some or all of the features shown and described herein. Unless otherwise noted, the schematic diagrams of the above-described embodiments shown in FIGS. 1, 3-11, and 15 are not intended to imply architectural limitations on the exemplary embodiments. Rather, they illustrate one exemplary structure, which should be understood as being capable of being varied. Accordingly, modifications, additions, and / or omissions may be made to the depicted structure. Furthermore, elements, features, and / or components serving similar, or at least substantially similar, purposes are labeled with like reference numerals in each of FIGS. 1, 3-11, and 15, and such elements, features, and / or components may not be described in detail herein with reference to FIGS. 1, 3-11, and 15. Similarly, not all elements, features, and / or components may be labeled with reference numerals in each of FIGS. 1, 3-11, and 15, although their associated reference numerals may be used herein for consistency.

[0150] In the above-referenced Figures 2 and 14, the blocks represent, for example, operations, steps, and / or portions thereof, and the lines connecting the various blocks do not imply a particular order or dependency of these operations or portions thereof. It should be noted that not all dependencies between the various operations disclosed are necessarily shown. Figures 2 and 14 and the accompanying disclosure describing operations in the methods described herein do not necessarily dictate the order in which these operations are performed. Rather, while suggesting one exemplary order, it should be understood that the order of these operations may be changed as appropriate. Accordingly, modifications, additions, and / or omissions may be made to the illustrated operations, and some operations may be performed in a different order or simultaneously. Furthermore, one skilled in the art will recognize that not all of the operations described need to be performed.

[0151] Furthermore, references to features, advantages, or similar terms throughout this specification do not imply that all features and advantages that may be realized by the embodiments disclosed herein should or are included in any one embodiment. Rather, a description of features and advantages means that the particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, references to features, advantages, and similar language used in this disclosure may, but do not necessarily, refer to the same embodiment.

[0152] The described features, advantages, and characteristics of one embodiment may be incorporated in any suitable manner into one or more other embodiments. Those skilled in the art will recognize that the various embodiments described herein can be practiced without one or more of the specific features or advantages of a particular embodiment. Also, in other cases, additional features and advantages may be recognized in a particular embodiment that are not present in all embodiments. Moreover, while various embodiments of system 100 and method 1000 have been shown and described, modifications will occur to those skilled in the art upon reading this specification. The present application includes such modifications and is intended to be limited only by the scope of the claims.

[0153] The present disclosure also includes the following notes:

[0154] Clause 1. A casting (156) configured to be placed over at least a portion of a composite structure (200) and to solidify to enclose at least said portion of said composite structure (200); an expansion medium (130) configured to expand such that the expansion medium (130) applies a positive pressure to the composite structure (200) and the casting (156).

[0155] Note 2. The casting (156) comprises a casting material (182); 2. The system (100) of claim 1, wherein the casting material (182) is configured to solidify upon a predetermined change in an attribute (184) of the casting material (182).

[0156] Clause 3. The system (100) of Clause 2, wherein the casting material (182) comprises a fiber-reinforced plastic.

[0157] Appendix 4. The system (100) of any one of appendices 1 to 3, further comprising a containment container (102) having an interior volume (114) and configured to enclose the casting (156) and at least the portion of the composite structure (200).

[0158] Appendix 5. The system (100) of Appendix 4, wherein the expandable medium (130) is disposed within the interior volume (114) between the restraining container (102) and the casting (156).

[0159] Clause 6. The system (100) of clause 5, wherein the interior volume (114) of the containment container (102) is selectively variable.

[0160] Appendix 7. The restraining container (102) a base (104) configured to support at least the portion of the composite structure (200); 7. The system (100) of claim 6, including a cover (106) coupled to the base (104).

[0161] Appendix 8. The system (100) of Appendix 7, wherein the cover (106) of the containment container (102) includes at least one of a plurality of walls (112) and an overlay (168).

[0162] Appendix 9. The system (100) of Appendix 8, further comprising an actuator (108) configured to move at least one of the walls (112) relative to at least another of the walls (112) to selectively vary the interior volume (114) of the containment container (102).

[0163] Clause 10. The system (100) of clause 8 or clause 9, wherein the expandable medium (130) is disposed between the cover (106) and the casting (156).

[0164] Appendix 11. The system (100) according to any one of appendices 7 to 10, wherein the cover (106) is movable relative to the base (104).

[0165] Appendix 12. The system (100) of any one of appendices 7 to 11, further comprising a retainer (120) configured to hold the cover (106) pressed against the composite structure (200).

[0166] Clause 13. The system (100) of clause 12, wherein the retainer (120) is configured to couple the cover (106) and the base (104).

[0167] Appendix 14. The system (100) of any one of appendices 1 to 13, further comprising a base (104) configured to support at least the portion of the composite structure (200).

[0168] Clause 15. The system (100) of clause 14, wherein the base (104) includes a hard mold (142).

[0169] Clause 16. The system (100) of clause 15, wherein the rigid mold (142) includes a molding surface (144) that corresponds to the cross-sectional shape (204) of the composite structure (200).

[0170] Clause 17. The system (100) of any one of clauses 1 to 16, further comprising a cowl (146) disposed between the expandable medium (130) and the composite structure (200).

[0171] Clause 18. The casting (156) has an interior volume (114); 4. The system (100) of any one of claims 1 to 3, wherein the expandable medium (130) is disposed within the internal volume (114) between the casting (156) and the composite structure (200).

[0172] Clause 19. The system (100) of clause 18, further comprising a reflector (186) disposed between the casting (156) and the expandable medium (130).

[0173] Clause 20. The system (100) of clause 18 or clause 19, further comprising a bagging material (188) disposed on the casting (156).

[0174] Appendix 21. The system (100) of any one of appendices 18 to 20, further comprising a retainer (120) configured to hold the casting (156) against the composite structure (200).

[0175] Addendum 22. The system (100) of any one of Addendums 1 to 21, wherein the casting (156), upon solidification, has a cross-sectional profile (118) corresponding to the cross-sectional shape (204) of the composite structure (200).

[0176] Appendix 23. The system (100) of any one of Appendixes 1 to 22, wherein the expansion medium (130) is configured to expand to a predetermined volume (132) when a predetermined change occurs in an attribute (134) of the expansion medium (130), such that the expansion medium (130) applies the positive pressure.

[0177] Appendix 24. The expandable medium (130) comprises expandable pellets (136); The expandable pellets (136) are heat activated at an activation temperature (152); 24. The system (100) of claim 23, wherein the expandable pellets (136) are configured to expand upon raising the temperature of the expandable pellets (136) to the activation temperature (152).

[0178] Clause 25. The composite structure (200) includes a plurality of composite layers (208); At least a portion of the plurality of composite layers (208) is uncured; 25. The system of claim 24, wherein the activation temperature of the expandable pellets is up to a curing temperature of the composite layers.

[0179] Clause 26. The system (100) of clause 24 or 25, wherein the expandable pellets (136) comprise foamable pellets (138).

[0180] Clause 27. The expandable medium (130) further comprises an encapsulation element (154); 27. The system (100) of any one of claims 24 to 26, wherein the expandable pellet (136) is disposed within the containment element (154).

[0181] Clause 28. The system (100) of any one of clauses 1 to 27, further comprising a heater (158) in thermal communication with the expandable medium (130).

[0182] Clause 29. Encasing at least a portion (202) of the composite structure (200) in a casting (156); expanding an expandable medium (130) to apply a positive pressure to the composite structure (200); and curing the composite structure (200).

[0183] Addendum 30. The step of encasing at least the portion (202) of the composite structure (200) in the casting (156) comprises: disposing a casting material (182); 29. The method of claim 28, further comprising solidifying the casting material upon a predetermined change in an attribute of the casting material.

[0184] Clause 31. Containing at least the portion of the composite structure (200) and the casting (156) in a containment container (102); 31. The method (1000) of claim 29 or 30, further comprising: disposing the expandable medium (130) within the interior volume (114) of the containment container (102).

[0185] Clause 32. Varying a property (134) of the expansion medium (130) to expand the expansion medium (130) to a predetermined volume (132); 32. The method (1000) of claim 31, further comprising applying a positive pressure to the casting (156) and the containment container (102).

[0186] Clause 33. The method (1000) of clause 31 or 32, further comprising selectively altering the interior volume (114) of the containment container (102).

[0187] Clause 34. The method (1000) of any one of Clauses 29-33, further comprising supporting at least the portion of the composite structure (200) on a base (104).

[0188] Clause 35. The method (1000) of clause 34, further comprising connecting a cover (106) to the base (104).

[0189] Clause 36. The method (1000) of clause 35, further comprising moving the cover (106) relative to the base (104).

[0190] Clause 37. The method (1000) of clause 29 or 30, further comprising disposing the expandable medium (130) within the interior volume (114) of the casting (156).

[0191] Clause 38. Varying a property (134) of the expandable medium (130) to expand the expandable medium (130) to a predetermined volume (132); 38. The method (1000) of claim 37, further comprising applying a positive pressure to the composite structure (200) and the casting (156).

[0192] Clause 39. The method (1000) of any one of Clauses 29-39, further comprising raising the temperature of the expandable medium (130) to at least an activation temperature (152).

[0193] Clause 40. The composite structure (200) includes a plurality of composite layers (208); 40. The method (1000) of claim 39, wherein at least a portion of the plurality of composite layers (208) is uncured.

[0194] Appendix 41. The method (1000) of Appendix 40, wherein at least one of the plurality of composite layers (208) is a composite patch (214) configured to repair a portion of a composite surface (206) of the composite structure (200).

[0195] Clause 42. A composite workpiece (210) comprising a composite structure (200) including a plurality of composite plies (208), At least a portion of the plurality of composite layers (208) is uncured; At least a portion (202) of the composite structure (200) is surrounded by a casting (156); A composite workpiece, wherein an expandable medium (130) is configured to expand to a predetermined volume (132) when a predetermined change occurs in a property (134) of the expandable medium (130), such that the expandable medium (130) applies a positive pressure to the composite structure (200).

[0196] Appendix 43. The composite workpiece (210) of Appendix 42, wherein at least one of the plurality of composite layers (208) is a composite patch (214) configured to repair a portion of a composite surface (206) of the composite structure (200).

[0197] Note 44. The expandable medium (130) comprises expandable pellets (136); The expandable pellets (136) are heat activated at an activation temperature (152); 44. The composite workpiece of claim 43, wherein the activation temperature of the expandable pellets is up to a curing temperature of the plurality of composite layers.

Claims

1. a casting configured to be disposed over at least a portion of the composite structure and to solidify to enclose at least the portion of the composite structure; an expansion medium configured to expand such that the expansion medium applies a positive pressure to the composite structure and the casting.

2. the casting comprises a casting material; the casting material is configured to solidify upon a predetermined change in an attribute of the casting material; The system of claim 1 , wherein the casting material comprises a fiber-reinforced plastic.

3. a containment container having an interior volume and configured to enclose the casting and at least the portion of the composite structure; the expandable medium is disposed within the interior volume between the restraining container and the casting; The system of claim 1 , wherein the interior volume of the containment container is selectively variable.

4. the containment container includes a base configured to support at least the portion of the composite structure and a cover coupled to the base; The system of claim 3 , wherein the cover of the restraint container includes at least one of a plurality of walls and an overlay.

5. an actuator configured to move at least one of the plurality of walls relative to at least another of the plurality of walls to selectively change the interior volume of the restraint container; The system of claim 4 , wherein the expandable medium is disposed between the cover and the casting.

6. The system of claim 4 , wherein the cover is movable relative to the base.

7. a retainer configured to hold the cover against the composite structure; The system of claim 4 , wherein the retainer is configured to couple the cover and the base.

8. further comprising a base configured to support at least the portion of the composite structure; the base comprises a hard mold; The system of claim 1 , wherein the rigid mold includes a molding surface that corresponds to a cross-sectional shape of the composite structure.

9. further comprising a cowl disposed between the inflatable medium and the composite structure; the casting has an interior volume; The system of claim 1 , wherein the expandable medium is disposed within the interior volume between the casting and the composite structure.

10. The system of claim 9 further comprising a reflector disposed between the casting and the expansive medium.

11. The system of claim 9 , further comprising a bagging material disposed over the casting and a retainer configured to hold the casting against the composite structure.

12. The system of claim 1 , wherein the casting, upon solidification, has a cross-sectional profile that corresponds to a cross-sectional shape of the composite structure.

13. 2. The system of claim 1, wherein the inflation medium is configured to expand to a predetermined volume when a predetermined change occurs in an attribute of the inflation medium, causing the inflation medium to provide the positive pressure.

14. the expandable medium comprises expandable pellets; the expandable pellets are heat activated at an activation temperature; the expandable pellets are configured to expand upon raising the temperature of the expandable pellets to the activation temperature; the composite structure includes a plurality of composite plies; at least a portion of the plurality of composite layers are uncured; The system of claim 13 , wherein the activation temperature of the expandable pellets is up to a curing temperature of the plurality of composite layers.

15. The system of claim 14 , wherein the expandable pellets comprise foamable pellets.

16. the expandable medium further comprises an encapsulation element; The system of claim 15 , wherein the expandable pellet is disposed within the containment element.

17. The system of claim 1 further comprising a heater in thermal communication with the expansive medium.

18. A method of using a system according to any one of claims 1 to 17, comprising: Encasing at least a portion of the composite structure in the casting; expanding the expandable medium to apply a positive pressure to the composite structure; and curing the composite structure.

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