Expandable medium with a flexible skin for use as tooling for composite material parts

Abstract

To provide a system and method for enhancing a consolidation process and achieving ease of removal in a manufacture of a composite component.SOLUTION: A system 10 for curing a composite component 200 includes: a mandrel 300 configured to receive and support the uncured composite component; a plurality of expandable pellets 100 placed in the uncured composite component; and a molding mold 450 configured to accommodate the mandrel, the uncured composite component, and the plurality of expandable pellets. The plurality of expandable pellets are configured to expand in accordance with a change of state or triggering event to apply positive pressure to the uncured composite component. Each of the plurality of expandable pellets includes a foaming agent, a polymer matrix configured to hold the foaming agent, and a flexible skin configured to encapsulate the polymer matrix and the foaming agent. The flexible skin is at least partially permeable to the foaming agent or gases released from the foaming agent.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure generally relates to the manufacture of composite parts, and more specifically to systems and methods for curing composite parts using expandable media.

Background Art

[0002] Composite materials are strong and lightweight materials composed of a combination of two or more functional materials, such as reinforcing fibers hardened with a polymer resin. By using composite parts, structural strength can be provided to various vehicles and structures. For example, in the manufacture of aircraft, composite stringers and composite panels can be used.

[0003] In the production of composite parts, generally, both pressurization and heating are required to perform the curing and consolidation processes of the composite parts. For example, a composite part preform before curing lacks structural strength. Therefore, forming tooling is used to press and hold the preform in a desired shape during the curing and consolidation processes. However, when the shape of the preform is complex or has cavities, it is difficult to press and hold such a preform in a desired shape. Also, there may be cases where it is difficult to remove the tooling or difficult to apply pressure evenly to the entire preform by the tooling.

[0004] Therefore, there is a need for systems and methods that enhance the consolidation process and ease of removal in the manufacture of composite parts, and that also address other potential problems.

Summary of the Invention

[0005] This summary is only a simplified overview of some aspects of one or more embodiments of the present disclosure. This summary is not comprehensive and is not intended to identify key or essential elements of the present teachings or to define the scope of the present disclosure. This summary is only intended to present one or more concepts in a simplified form as a prelude to the description that follows. To achieve the above and / or other aspects and utilities, the following system for curing a composite part is provided. That is, a mandrel configured to receive and support an uncured composite part, a plurality of expandable pellets disposed on the uncured composite part, and a mold configured to accommodate the mandrel, the uncured composite part, and the plurality of expandable pellets, wherein the plurality of expandable pellets are configured to expand in accordance with a change of state or a trigger event to apply a positive pressure to the uncured composite part, and each of the plurality of expandable pellets includes a blowing agent, a polymer matrix configured to hold the blowing agent, and a flexible skin configured to encapsulate the polymer matrix and the blowing agent, and the flexible skin has at least partial permeability to the blowing agent or a gas released from the blowing agent.

[0006] The flexible skin can be configured to control the expansion of each of the plurality of expandable pellets.

[0007] The flexible skin can control the expansion of each of the plurality of expandable pellets by restricting leakage of the blowing agent or a gas released from the blowing agent.

[0008] Controlling the expansion of each of the plurality of expandable pellets can include at least one of expanding each of the plurality of expandable pellets and maintaining the expanded state of each of the plurality of expandable pellets.

[0009] The expanded state can be maintained for any of the time lengths of at least 20 minutes, at least 30 minutes, at least 40 minutes, at least 60 minutes, at least 2 hours, or at least 5 hours.

[0010] The foaming agent may be configured to release gas in response to a change in state or a trigger event, and the rate at which gas is released from the foaming agent in response to the change in state or the trigger event may be configured to exceed the rate at which the gas leaks through the flexible skin such that each of the plurality of expandable pellets expands or maintains an expanded state.

[0011] The polymer matrix may be configured to release the foaming agent in response to a change in state or a trigger event, and the rate at which the foaming agent is released from the polymer matrix in response to the change in state or the trigger event may be configured to exceed the rate at which the foaming agent leaks through the flexible skin such that each of the plurality of expandable pellets expands or maintains an expanded state. The foaming agent is one that expands in volume in response to a change in state or a trigger event, and the rate at which the foaming agent leaks through the flexible skin may be a rate at which each of the plurality of expandable pellets will expand or maintain an expanded state.

[0012] The polymer matrix may include a thermoplastic polymer.

[0013] The polymer matrix may include at least one of polyurethane (PU), polypropylene (PP), polycarbonate (PC), polyetherimide (PEI), polystyrene (PS), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), (poly)methyl methacrylate (PMMA), nylon, and vinyl.

[0014] The flexible skin may include a thermoplastic elastomer (TPE). The flexible skin may include at least one of silicone, rubber, polyurethane (PU), and polyethylene (PE).

[0015] The blowing agent may include at least one of a chemical blowing agent and a physical blowing agent.

[0016] The chemical blowing agent may be configured to release gas in accordance with the state change or trigger event. The chemical blowing agent may contain at least one of isocyanate, azodicarbonamide, hydrazine, toluenesulfonyl semicarbazide, sodium bicarbonate, or citric acid.

[0017] The aforementioned physical blowing agent may include a thermally expandable physical agent.

[0018] The physical blowing agent may include at least one of an inert, non-flammable gas, a flammable gas, a hydrocarbon, or water vapor.

[0019] The foaming agent may further contain functional additives that further promote foaming.

[0020] The flexible skin may be configured to allow the foaming agent to be reinjected into the polymer matrix.

[0021] The aforementioned state change or trigger event may include one or more of the following: a temperature change, a pressure change, a chemical reaction, or an input of radiant energy.

[0022] To achieve the above-described and / or other embodiments and usefulness, the following method for curing a composite component is provided: a method comprising placing an uncured composite component on a mandrel, placing a plurality of expandable pellets on the uncured composite component, expanding the plurality of expandable pellets, and applying positive pressure to the uncured composite component, wherein each of the plurality of expandable pellets comprises a foaming agent, a polymer matrix configured to hold the foaming agent, and a flexible skin configured to enclose the polymer matrix and the foaming agent, the flexible skin having at least partial permeability to the foaming agent or gases released from the foaming agent, and the flexible skin configured to control the expansion of each of the plurality of expandable pellets.

[0023] The flexible outer layer can control the expansion of each of the plurality of expandable pellets by limiting the leakage of the foaming agent or gas released from the foaming agent.

[0024] The above method may further include reinjecting the plurality of expandable pellets and reusing the expandable pellets.

[0025] To achieve the above-described and / or other embodiments and usefulness, the following expandable pellets are provided: expandable pellets for use in curing composite components, comprising: a foaming agent; a polymer matrix configured to hold the foaming agent; and a flexible skin configured to enclose the polymer matrix and the foaming agent, wherein the flexible skin is at least partially permeable to the foaming agent or gases released from the foaming agent, and the flexible skin is configured to control the expansion of each of the plurality of expandable pellets.

[0026] The flexible outer layer can control the expansion of each of the plurality of expandable pellets by limiting the leakage of the foaming agent or gas released from the foaming agent.

[0027] For other applicable fields, it will become clear from the following description. It should be understood that the following description and the description of individual embodiments show preferred embodiments of the present invention, but are for illustrative purposes only and do not limit the scope of the present invention.

Brief Description of the Drawings

[0028] The accompanying drawings, which form a part of this specification, illustrate aspects of the present teachings and, together with the following description, explain the principles of the present disclosure.

[0029] [Figure 1-2] It is a diagram showing a system for curing a composite part according to an embodiment of the present disclosure. [Figure 3-4] It is a diagram showing a system for curing a composite part according to an embodiment of the present disclosure. [Figure 5] It is a diagram showing an expandable pellet according to one aspect. [Figure 6] It is a diagram showing a method for curing a composite part according to an embodiment. [Figure 7] It is a flowchart showing a method of manufacturing and using an aircraft. [Figure 8] It is a block diagram showing an aircraft.

Modes for Carrying Out the Invention

[0030] The accompanying drawings are drawn with some details simplified for the purpose of assisting in the understanding of the present teachings, and priority is not given to maintaining structural accuracy, detail of details, and scale precisely.

[0031] The following describes the details of exemplary embodiments of the present teachings. The accompanying drawings show the examples. Generally, the same reference numerals are used in all the drawings for the same or similar parts.

[0032] Throughout this specification and the claims, the following terms have the meanings expressed below, unless otherwise clearly inconsistent with the context. Expressions such as “in one embodiment,” “in a particular embodiment,” and “in several embodiments” as used herein may, but not necessarily, refer to the same embodiment. Furthermore, expressions such as “in another embodiment” and “in several other embodiments” may, but not necessarily, refer to different embodiments. As will be discussed later, various embodiments can be readily combined without departing from the scope or essence of this disclosure.

[0033] As used herein, the terms “or” are used as inclusive operators unless they are clearly inconsistent in the context. The same applies to the terms “and” or “or.” The term “based on” is not exclusive, unless it is clearly inconsistent in the context, and may also be based on additional factors not described herein. In this specification, “at least one of A, B, and C” includes embodiments including A, B, or C; embodiments including multiple examples of A, B, or C; or embodiments such as combinations of A and B, A and C, B and C, A, B and B, B and C, and A, B and C. In addition, throughout this specification, singular descriptions also include the meaning of referring to multiple things. “Inside” also includes the meaning of “inside” and “on top of.” Similarly, embodiments of this disclosure are appropriately interpreted as including / equipping elements A, B, C, etc., consisting of these elements, or essentially consisting of these elements.

[0034] Furthermore, while terms such as "first," "second," etc., are used in this specification to describe various elements, these terms do not limit the elements in question. These terms are merely used to distinguish one element from another. For example, defining a first object, component, or step as a second object, component, or step, and defining a second object, component, or step as a first object, component, or step, does not deviate from the scope of the present invention. The first object, component, or step and the second object, component, or step are both objects, components, or steps, but they are not identical to each other. Also, where terms such as "includes," "includes," "equips," and / or "equips" are used in this specification, these indicate the existence of the described features, steps, processes, elements, and / or components, but do not negate the existence or addition of one or more other features, steps, processes, elements, components, and / or sets thereof. Furthermore, the term "hypothetically" as used herein means, depending on the context, "in the event of," "when," "when it is determined to be," or "when it is detected," etc.

[0035] Unless otherwise specified, all physical properties defined herein shall be measured at temperatures between 20 and 25 degrees Celsius.

[0036] Numerical ranges described herein should be interpreted as including all integers and / or fractions between the maximum and minimum values ​​of the range, as well as the values ​​at both ends. For example, the range from 0.5% to 6% explicitly includes intermediate values ​​such as 0.6%, 0.7%, and 0.9%, as well as all values ​​up to the upper end, such as 5.95%, 5.97%, and 5.99%, and many other values. The same description applies to other numerical attributes and / or elemental ranges described herein, unless there is an obvious contradiction.

[0037] In addition, all numerical values ​​refer to "approximate" or "roughly" values, taking into account experimental errors and variability that can be predicted by those skilled in the art. All numerical values ​​and numerical ranges in this disclosure should be understood as approximate values ​​and approximate ranges. Furthermore, the terms "approximately," "substantially," "effectively," or "roughly" used in relation to any quantity or measurement mean that the described features, parameters, or values ​​are not necessarily required to be strictly achieved. For example, deviations or variability due to tolerances, measurement errors, measurement accuracy limits, or other factors known to those skilled in the art are included in any quantity, but this does not preclude the effects achieved by the relevant characteristics.

[0038] Unless otherwise specified, all percentage values ​​and amounts mentioned herein and elsewhere are weight percent. The percentages and amounts of a material are based on its active weight. For example, the amount of an active ingredient provided as a solution can be determined based on the amount of the active ingredient minus the amount of the solvent, or by the weight reduction due to the evaporation of the solvent.

[0039] The procedures, methods, techniques, and workflows described herein may, in some embodiments, be combined with and / or have their order altered.

[0040] In the fabrication of composite parts such as carbon fiber reinforced polymer (CFRP) parts, a laminate called a "preform" is first formed by laminating multiple layers. As used herein, the terms "uncured composite part" or "preform" refer to one or more plies of resin-impregnated composite material. An uncured composite part is, for example, a fiber-reinforced uncured thermosetting polymer composite part. The individual fibers in each layer of the preform are oriented parallel to each other, but the fibers in different layers are arranged in different orientations to enhance the strength of the composite part in different dimensional directions. The preform contains a viscous resin, which solidifies as it hardens, forming a composite part (for example, for aircraft). A carbon fiber ply impregnated with uncured thermosetting resin or thermoplastic resin is also called a "prepreg." As used herein, the term "prepreg" refers to a laminate of pre-impregnated composite plies such as epoxy resin-impregnated unidirectional composite tape or carbon fiber. Prepregs are often cured by heat and pressure, or in an autoclave, but they retain their flexibility before curing. Other types of carbon fibers include "dry fibers," which may contain tackifiers or binders but not thermosetting resins. Dry fibers may have resin injected before curing. The solidification of thermosetting resins is a unidirectional process called curing. In contrast, thermoplastic resins can be returned to a viscous state by reheating the resin.

[0041] Curing of fiber-reinforced thermoplastic polymer composite components generally refers to crosslinking and compacting the fibers of the fiber-reinforced thermosetting polymer composite component by applying heat and / or pressure. While thermosetting resins can be partially cured (i.e., crosslinked) without pressurization, such components often suffer from insufficient compaction. Therefore, the terms "curing" and "to cure" as used herein include applying both heating (for curing / crosslinking) and pressurization (for compaction) to fiber-reinforced thermosetting polymer composite components, such as the thermosetting composite components of this disclosure.

[0042] In some embodiments, composite components are cured by heating and / or pressurizing. This heating and / or pressurizing is carried out according to a predetermined curing schedule that specifies the pressure to be applied, the temperature, the duration of pressurizing and / or heating, etc. In some embodiments, composite components are cured by pressurizing alone. For example, composite components are cured by pressurizing at room temperature. The pressure in this case can be positive or negative. The pressure is applied, for example, through a vacuum. These scheduled temperatures and / or pressures may also be referred to as the curing temperature profile and the consolidation pressure profile. In this specification, “maximum curing temperature” refers to the highest temperature in the curing temperature profile, and “maximum curing pressure” refers to the highest pressure in the consolidation pressure profile.

[0043] In the manufacturing of composite materials, there is a need for a system and method that can equalize the pressure applied during the compaction process and facilitate the removal of the composite material components.

[0044] A system for curing a composite component according to embodiments of the present disclosure generally comprises a plurality of expandable pellets or a medium configured to expand during the curing process and apply positive pressure to the uncured composite component. Typically, the expandable pellets are placed in an uncured state on the uncured composite component. The expandable pellets are, for example, placed around the uncured composite component and / or within a cavity defined by the uncured composite component. The expandable pellets expand during the curing process and apply positive pressure to the uncured composite component, allowing the uncured composite component to maintain a desired shape during curing.

[0045] A system for curing composite components generally comprises a mandrel configured to receive and support an uncured composite component, and a plurality of expandable pellets placed on the uncured composite component. The plurality of expandable pellets are configured to expand during the curing process to apply positive pressure to the uncured composite component.

[0046] As will be described in detail later, according to embodiments of the present disclosure, a system for curing a composite component comprises a mandrel configured to receive and support an uncured composite component; a plurality of expandable pellets arranged on the uncured composite component; and a mold configured to house the mandrel, the uncured composite component, and the plurality of expandable pellets. The plurality of expandable pellets may be configured to expand in accordance with a change of state or a triggering event to apply positive pressure to the uncured composite component. Each of the plurality of expandable pellets may include a blowing agent, a polymer matrix configured to hold the blowing agent, and a flexible skin configured to enclose the polymer matrix and the blowing agent. The flexible skin is at least partially permeable to the blowing agent or gases released from the blowing agent. The flexible skin may be configured to control the expansion of each of the plurality of expandable pellets by limiting the leakage of the blowing agent or gases released from the blowing agent.

[0047] Figures 1 and 2 show a system for curing composite parts according to one embodiment of the present disclosure. As shown in Figures 1 and 2, the system 10 includes a mold cover 400, a cowl plate 500, a mandrel 300, an uncured composite part 200, and a plurality of expandable pellets 100.

[0048] In one embodiment, the mold cover 400 is configured to form a mold 450 by being attached to a cowl plate 500. The mold 450 is configured to house a mandrel 300, an uncured composite component 200, and a plurality of expandable pellets 100. In some embodiments, the mold 450 is airtight. In other embodiments, the mold 450 is not airtight. For example, the mold 450 may be configured not to be airtight on its own and unable to maintain consolidation pressure during the curing process. In other embodiments, the mold 450 is configured to house a plurality of expandable pellets 100 in an expanded state. The mold 450 is configured to house the expandable pellets 100 and, as the housed expandable pellets expand during the curing process, apply positive pressure to the uncured composite component 200.

[0049] In Figures 1 and 2, the cowl plate 500 and mold cover 400 are shown as the mold 450, but the disclosure is not limited thereto. In other embodiments, the mold 450 can be realized as other devices, such that it houses the expandable pellets 100 and, as the expandable pellets expand during the curing process, a positive pressure is applied to the uncured composite component 200. For example, the mold 450 may be configured as a mesh bag surrounding a mandrel 300, the uncured composite component 200, and a plurality of expandable pellets 100. In other embodiments, the mold 450 can be realized as an oven or autoclave that airtightly or airtightly houses the mandrel 300, the uncured composite component 200, and the plurality of expandable pellets 100.

[0050] In one embodiment, the mandrel 300 is placed inside the mold 450, and the uncured composite parts 200 are stacked on the upper surface 330 of the mandrel 300. The multiple expandable pellets 100 are configured to expand inside the mold 450 during the curing process, pressing against the mold and applying positive pressure to the uncured composite parts 200. For example, as shown in Figure 2, when expanded, the expandable pellets 100 fill substantially the entire internal space of the mold 450, causing the uncured composite parts 200 to conform to the desired shape during the curing process.

[0051] In some embodiments, the mandrel 300 is configured to heat the uncured composite part 200 during the curing process. In some embodiments, the heat is applied externally. For example, the system 10 is placed in a heating furnace or autoclave configured to heat the uncured composite part 200 during the curing process. In other embodiments, the heat is applied externally by placing a heating lamp or heating blanket on the bag-shaped mesh constituting the mold 450. In yet another embodiment, the curing process occurs at room temperature, and the uncured composite part 200 is not heated.

[0052] Figures 3 and 4 show a system 20 for curing a composite component according to one embodiment of the present disclosure. As shown in Figures 3 and 4, the system 20 includes a mandrel 300, an uncured composite component 200, and a plurality of expandable pellets 100.

[0053] As shown in Figures 3 and 4, the uncured composite component 200 defines one or more internal cavities 250, and the multiple expandable pellets 100 are placed in at least one of these one or more internal cavities 250. The multiple expandable pellets 100 are configured to expand during the curing process to at least partially fill at least one internal cavity 250 and apply positive pressure to the uncured composite component 200.

[0054] As shown in Figures 3 and 4, the mandrel 300 is configured to receive and support the uncured composite material part 200. The mandrel 300 includes an upper mandrel 310 and a lower mandrel 320. The upper portion of the uncured composite material part 200 has an upper surface 232, which is laminated onto the surface 312 of the upper mandrel 310. The lower portion of the uncured composite material part 200 has a lower surface 234, which is laminated onto the surface 322 of the lower mandrel 320. Subsequently, by joining the upper mandrel 310 and the lower mandrel 320 together, the uncured composite material part 200 can be made to conform to the desired shape during the curing process.

[0055] As shown in Figures 3 and 4, the uncured composite component 200 has an internal cavity 250. The boundary of the internal cavity 250 is defined by an inner surface 236. As shown in Figure 4, when the expandable pellet 100 expands, it conforms substantially the entire internal cavity 250, including the inner corners 238, to the desired shape.

[0056] In some embodiments, at least one of the upper mandrel 310 and the lower mandrel 320 is configured to heat the uncured composite component 200 during the curing process. In other embodiments, the mandrel 300 is not configured to heat the uncured composite component 200 during the curing process. Instead, heat is applied externally. For example, the mandrel 300 is placed in a heating furnace or autoclave configured to heat the uncured composite component 200 during the curing process. In other embodiments, the curing process may occur at room temperature.

[0057] As shown in Figures 2 and 4, the expandable pellet 100 expands during the curing process. In one embodiment, the expandable pellet 100 is configured to expand in response to a predetermined state change or trigger event. For example, the expandable pellet 100 expands in response to a change in temperature, a change in pressure, a chemical reaction, and / or the input of radiant energy (e.g., irradiation with UV light). In some embodiments, the expandable pellet 100 expands in response to a single state change. A change in temperature is one example. In other embodiments, the expandable pellet expands in response to one or more state changes, or a combination of one or more state changes. A simultaneous occurrence of a change in temperature and a change in pressure is one example. Therefore, a predetermined state change includes a change in temperature, a change in pressure, a chemical reaction, and the input of radiant energy (e.g., irradiation with UV light). A predetermined state change may further include one or more of the following, and / or a combination thereof: a change in temperature, a change in pressure, a chemical reaction, and the input of radiant energy (e.g., irradiation with UV light).

[0058] Figure 5 shows an expandable pellet according to one embodiment. As shown in Figure 5, the expandable pellet 100 comprises a flexible outer layer 110, a polymer matrix 120, and a foaming agent 150. In some embodiments, the expandable pellet 100 further comprises a core 130 and / or a nucleus 140.

[0059] The polymer matrix 120 is configured to hold the blowing agent 150. For example, the polymer matrix 120 has a free volume, and the blowing agent 150 can be held in its volumetric space. In another embodiment, the polymer matrix 120 has a plurality of nanometer-scale voids, and the blowing agent 150 can be held in these voids. In yet another embodiment, the polymer matrix 120 is formed to surround the blowing agent 150 or is mixed with the blowing agent. For example, the blowing agent 150 is a powder, pellet, or liquid mixed with the polymer matrix 120. In some embodiments, the blowing agent 150 may form a core 130 and / or nucleus 140, with the polymer matrix 120 formed around it. In another embodiment, the blowing agent 150 is dissolved in the polymer matrix 120.

[0060] The polymer matrix 120 comprises thermoplastic polymers and / or elastomer materials. For example, the polymer matrix 120 may include polyurethane (PU), polypropylene (PP), polycarbonate (PC), polyetherimide (PEI), polystyrene (PS), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), and (poly)methyl methacrylate (PMMA), nylon, vinyl, and the like. In some embodiments, the polymer matrix 120 comprises a high-temperature thermoplastic polymer. In other embodiments, the polymer matrix 120 comprises a low-temperature thermoplastic polymer.

[0061] In some embodiments, the polymer matrix 120 comprises a single thermoplastic material. For example, the polymer matrix 120 is essentially composed of PMMA. In other embodiments, the polymer matrix 120 consists of one or more thermoplastic materials, or a combination of one or more thermoplastic materials. For example, the polymer matrix includes, or is essentially composed of, PVC and PMMA, or thermoplastic acrylic-polyvinyl chloride (e.g., Kydex®, a thermoplastic material manufactured by Sekisui SPI in Bloomsburg, Pennsylvania).

[0062] The polymer matrix 120 may be configured not to melt during the curing process. Therefore, in some embodiments, the melting point of the polymer matrix is ​​higher than the maximum curing temperature. For example, the melting temperature of the polymer matrix 120 is at least 150°F, at least 200°F, at least 300°F, or at least 350°F. In other embodiments, the melting temperature of the polymer matrix is ​​about 50°F to about 850°F, about 100°F to about 600°F, or about 200°F to about 400°F. In some embodiments, the melting point of the polymer matrix 120 is lower than the melting point of the flexible skin 110.

[0063] The polymer matrix 120 is expandable in accordance with the activation of the blowing agent 150. That is, the blowing agent 150 is activated in accordance with a predetermined state change or trigger event, and the polymer matrix expands in accordance with the activation of the blowing agent 150, thereby causing the expandable pellet 100 to expand.

[0064] In another embodiment, the polymer matrix 120 is configured not to expand even when the blowing agent 150 is activated. Instead, the polymer matrix 120 is configured to release gas when the blowing agent 150 is activated, and this gas release causes the flexible outer layer 110 to expand, which in turn causes the expandable pellets 100 to expand.

[0065] The blowing agent 150 includes a gas or liquid configured to react in response to a predetermined change of state or trigger event. The blowing agent 150 may be a gas or a liquid, and may be, for example, carbon dioxide, nitrogen, one or more hydrocarbons, water, and / or other suitable physical and / or chemical blowing agents 150 configured to react in response to a predetermined change of state or trigger event.

[0066] In other embodiments, the foaming agent 150 includes a gas, powder, supercritical gas, and / or other components configured to react in response to a predetermined state change or trigger event. The foaming agent 150 may include only a single gas, a single solid, or a single liquid. In other embodiments, the foaming agent 150 may include a combination of multiple gases, a combination of multiple solids, a combination of multiple liquids, or a combination of gas, solid, and liquid.

[0067] In one embodiment, the flexible skin 110 restricts the leakage of the blowing agent 150 or gas released from the blowing agent 150 so that the expandable pellets 100 expand and / or maintain an expanded state when the blowing agent 150 is activated. For example, the flexible skin 110 controls the expansion of the expandable pellets 100 by suppressing the leakage of the blowing agent 150 or gas released from the blowing agent 150.

[0068] In one embodiment, maintaining the expansion of each expandable pellet 100 includes at least one of expanding the expandable pellet 100 and maintaining the expanded state of the expandable pellet 100. The expanded state is maintained for a duration of at least 20 minutes, at least 30 minutes, at least 40 minutes, at least 60 minutes, at least 2 hours, or at least 5 hours.

[0069] In some embodiments, the foaming agent 150 releases gas in response to a change in state or a trigger event, and the rate at which the gas is released from the foaming agent 150 in response to the change in state or trigger event exceeds the rate at which the released gas permeates and leaks out through the flexible skin 110, so that the expandable pellet 100 expands or maintains an expanded state.

[0070] In some embodiments, the polymer matrix 120 releases a foaming agent 150 in response to a change of state or trigger event, and the rate at which the foaming agent 150 is released from the polymer matrix 120 in response to the change of state or trigger event exceeds the rate at which the released foaming agent 150 permeates and leaks out through the flexible surface 110, so that each expandable pellet expands or maintains an expanded state.

[0071] In some embodiments, the foaming agent 150 expands in volume in response to a change of state or trigger event, and the rate at which the expanded foaming agent 150 leaks out through the flexible skin 110 is the rate at which the expandable pellet expands or maintains its expanded state.

[0072] The blowing agent 150 may be either a chemical blowing agent 150 or a physical blowing agent 150. The blowing agent 150 may be a combination of a physical blowing agent 150 and a chemical blowing agent 150, or the blowing agent 150 may essentially contain only one of either a physical blowing agent 150 or a chemical blowing agent 150.

[0073] The predetermined state change or trigger event further includes one or more of the following: temperature change, pressure change, chemical reaction, and input of radiant energy (e.g., UV light irradiation), and combinations thereof. For example, the physical blowing agent 150 changes to a gas phase or increases in volume in accordance with a predetermined state change such as a temperature change. The chemical blowing agent 150 releases gas in accordance with a state change such as a temperature change, chemical reaction, or exposure to UV light.

[0074] In some embodiments, the predetermined state change is a single state change. In other embodiments, the predetermined state change includes one or more state changes, or a combination of one or more state changes.

[0075] In some embodiments, the blowing agent 150 comprises one or more types of chemical blowing agents 150. The chemical blowing agent 150 can be synthesized or mixed with the polymer matrix 120. For example, the chemical blowing agent 150 is a powder, pellet, or liquid mixed with the polymer matrix 120. In other embodiments, the polymer matrix 120 functions as a carrier for the chemical blowing agent 150.

[0076] The chemical blowing agent 150 is configured to release gas according to a change of state or chemical reaction once activated. At least one of the polymer matrix 120, the flexible skin 110, and the expandable pellet 100 expands in accordance with this gas release.

[0077] The expansion of the expandable pellet 100 can be controlled by the balance between the gas released from the chemical blowing agent 150 contained in the polymer matrix 120 and the gas released from the chemical blowing agent 150 that permeates through the flexible outer layer 110 and leaks out of the expandable pellet 100. Therefore, the rate at which gas is released from the chemical blowing agent 150 in response to a predetermined state change or trigger event exceeds the rate at which the gas released from the chemical blowing agent 150 permeates through the flexible outer layer 110 and leaks out.

[0078] In some embodiments, the flexible skin 110 is impermeable to gas released from the chemical blowing agent 150. In other embodiments, gas released from the chemical blowing agent 150 permeates and diffuses through the flexible skin. However, the rate at which the gas permeates and diffuses through the flexible skin 110 is slower than the rate at which gas is released from the activated chemical blowing agent 150, so that the expandable pellet 100 expands and / or maintains its expanded state. In one embodiment, the flexible skin 110 restricts the leakage of gas released from the activated chemical blowing agent 150, thereby causing the expandable pellet 100 to expand and / or maintain its expanded state. For example, the rate at which gas is released from the blowing agent in response to a predetermined state change or trigger event is 2, 5, 10, or 20 times faster than the rate at which gas released from the chemical blowing agent 150 permeates and leaks through the flexible skin 110.

[0079] In some embodiments, the expandable pellets maintain an expanded state throughout the curing cycle. For example, the expandable pellet 100 maintains an expanded state for at least 10 minutes, at least 20 minutes, at least 30 minutes, and at least 1 hour. The expandable pellet 100 maintains an expanded state for about 10 minutes to about 2 hours. The expandable pellet 100 maintains an expanded state at the curing temperature.

[0080] The chemical blowing agent 150 cannot be reinjected. In other words, once the chemical blowing agent 150 has released a certain amount of gas in accordance with a change of state or trigger event, it becomes used and can no longer release any more gas.

[0081] Chemical blowing agents 150 include, for example, isocyanates, azodicarbonamides, hydrazines, toluenesulfonyl-semicarbaside, sodium bicarbonate, and citric acid. Other materials that can be used as chemical blowing agents 150 include, for example, benzenesulfonyl hydrazide, 5-phenyltetrazole, and dinitrozopentamethylentetraamine.

[0082] In other embodiments, the blowing agent 150 comprises one or more types of physical blowing agents 150. The physical blowing agent 150 is mixed with or retained in the polymer matrix 120. The physical blowing agent 150 is, for example, a gas sealed in the free volume space or internal interstitial voids of the polymer matrix 120. In some embodiments, the polymer matrix 120 functions as a carrier for the physical blowing agent 150, or the physical blowing agent 150 is dissolved in the polymer matrix 120. For example, the physical blowing agent 150 can be dissolved in the polymer matrix 120 until it reaches a saturation state. The physical blowing agent 150 is activated in response to a change of state or trigger event, such as a change in temperature. For example, as the temperature rises, the solubility of the physical blowing agent 150 in the polymer matrix 120 decreases, so that the physical blowing agent 150 is separated from the polymer matrix 120 and / or the volume of the physical blowing agent 150 increases. Simultaneously, the polymer matrix 120 softens due to the heating (usually to a temperature higher than the glass transition temperature Tg of the polymer matrix 120). The supersaturated physical blowing agent 150 forms bubble nuclei in the softened polymer matrix 120, promoting bubble growth and / or expansion of the polymer matrix 120. This increases the volume of the polymer matrix 120, the flexible skin 110, and the expandable pellets 100.

[0083] The expansion of the expandable pellet 100 can be controlled by the balance between the physical blowing agent 150 released from the polymer matrix 120 and the physical blowing agent 150 that permeates the flexible outer layer 110 and leaks out of the expandable pellet 100. Therefore, the rate at which the physical blowing agent 150 is released from the polymer matrix 120 in response to a predetermined state change or trigger event exceeds the rate at which the physical blowing agent 150 permeates the flexible outer layer 110 and leaks out. For example, the rate at which the physical blowing agent 150 is released in response to a predetermined state change or trigger event is 2, 5, 10, or 20 times faster than the rate at which the physical blowing agent 150 permeates the flexible outer layer 110 and leaks out.

[0084] In some embodiments, the flexible skin 110 is impermeable to gases released from the physicoblasting agent 150. In other embodiments, the physicoblasting agent 150 diffuses through the flexible skin 110. However, the rate at which the physicoblasting agent diffuses through the flexible skin 110 is slower than the rate at which the physicoblasting agent 150 is released from the activated polymer matrix 120, so that the expandable pellet 100 expands and / or remains expanded. In one embodiment, the flexible skin 110 restricts the leakage of the activated physicoblasting agent 150, causing the expandable pellet 100 to expand and / or remain expanded. In some embodiments, the expandable pellet remains expanded throughout the entire curing cycle. In some embodiments, the expandable pellet 100 remains expanded for at least 10 minutes, at least 20 minutes, at least 30 minutes, and at least 1 hour. The expandable pellet 100 remains expanded for, for example, from about 10 minutes to about 2 hours. The expandable pellet 100 maintains its expanded state at the curing temperature.

[0085] Examples of physical blowing agents 150 include thermally expandable physical agents such as chlorofluorocarbons, hydrochlorofluorocarbons, hydrocarbons, liquid CO2, or water vapor. Other materials that can be used as physical blowing agents 150 include inert non-flammable gases such as carbon dioxide, helium, and nitrogen, as well as flammable gases and materials such as propane, isobutane, pentane, ethanol, DME, and LPG, and chemical blowing agents such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs).

[0086] The physical blowing agent 150 can return to its original state after a predetermined state change or trigger event. For example, the physical blowing agent 150 separates from the polymer matrix 120 or expands the polymer matrix 120 in accordance with temperature changes, but returns to its original state or volume when cooled. In some embodiments, the polymer matrix 120 and the expandable pellets 100 can maintain their expanded shape without significant shrinkage after activation of the blowing agent 150. For example, the polymer matrix 120 and the expandable pellets 100 maintain their expanded state by plastic deformation even after the blowing agent 150 returns to its initial state and / or cools down. In other embodiments, the polymer matrix 120 and the expandable pellets 100 collapse or elastically return to their original size and shape after the physical blowing agent 150 returns to its initial state and / or cools down.

[0087] In some embodiments, the expandable pellets 100 are deformable. For example, the expandable pellets 100 are at least partially deformable after, during, and / or before the reaction of the foaming agent 150. By deforming to a certain extent, the expandable pellets 100 fill in the gaps that may exist between the particles of the expandable pellets 100, between the expandable pellets 100 and the inner or outer surface of the uncured composite part 200, and / or between the expandable pellets 100 and the mold 450 or mandrel 300. By filling such gaps with multiple expandable pellets 100, a substantially smooth surface can be formed on the uncured composite part 200, and positive pressure can be applied more uniformly to the uncured composite part 200.

[0088] The foaming agent 150 may contain functional additives that promote foaming. For example, if the foaming agent 150 contains gas, the functional additive may be a material that promotes bubble formation, such as a surfactant. Suitable foaming agents include sodium laureth sulfate (SLS), sodium lauryl ether sulfate (SLES), sodium lauryl sulfate (also known as sodium dodecyl sulfate or SDS), and ammonium lauryl sulfate (ALS).

[0089] If the blowing agent 150 is a gas or liquid, it can be introduced into the expandable pellet 100 under pressure. How much of the blowing agent 150 the polymer matrix 120 can hold depends on the solubility of the blowing agent 150 in the polymer matrix 120. Generally, lower temperatures result in lower diffusivity and higher solubility. Similarly, higher temperatures result in higher diffusivity and lower solubility.

[0090] Therefore, it is possible to "inject" the foaming agent 150 into the polymer matrix 120, and in the case of CO2, a sufficient amount of gas can be absorbed into the polymer matrix 120 over a long period of time (several hours to several days) in a high-pressure environment of 5 MPa, for example, at a low temperature such as room temperature, and a steady state in which the polymer matrix 120 contains a predetermined concentration of gas can be achieved. When heated, this steady state is broken and the solubility decreases, so the foaming agent 150 detaches from the free volume of the polymer matrix 120 and / or its volume increases, causing the expandable pellets 100 to expand. In some embodiments, the polymer matrix 120 functions as a storage section that holds and releases the foaming agent 150. The flexible skin 110 functions as a barrier that reduces the rate at which the gas of the foaming agent 150 leaks out and diffuses from the expandable pellets 100, so that in response to a change of state or a trigger event, the expandable pellets 100 can continuously increase in volume without collapsing and / or maintain their expanded state.

[0091] In one embodiment, the flexible skin 110 is permeable to the foaming agent 150, allowing the foaming agent to be injected into the polymer matrix. The solubility of the foaming agent 150 in the polymer matrix 120 is sufficiently high to hold a sufficient amount of foaming agent 150 to expand the expandable pellets 100. For example, the polymer matrix 120 can hold enough foaming agent 150 to apply positive pressure to the uncured composite component 200 during the curing process when the expandable pellets 100 are in an expanded state. For example, the polymer matrix 120 in each expandable pellet 100 can hold enough foaming agent 150 to expand the expandable pellet 100 to about 1.2 to 10 times its original volume. The polymer matrix 120 can hold enough foaming agent 150 to expand the expandable pellet 100 to 1.2, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times its original volume. The polymer matrix 120 can hold enough foaming agent 150 to expand the expandable pellets 100 to at least 2, 4, 6, 8, or 10 times their original volume. The polymer matrix 120 can hold enough foaming agent 150 to expand the expandable pellets 100 to about 1.5 to about 50 times their original volume.

[0092] The injection into the polymer matrix 120 is initiated at a high temperature so that the foaming agent 150 can permeate the flexible epidermis 110 and rapidly diffuse into the polymer matrix 120. Subsequently, the injection into the polymer matrix 120 is continued at a low temperature, such as room temperature, allowing the polymer matrix 120 to absorb even more of the foaming agent 150.

[0093] In some embodiments, the expandable pellets 100 are reinjected after the curing cycle. For example, the physical blowing agent 150 can be reinjected. That is, after the curing cycle, the physical blowing agent 150 can be reinjected into the polymer matrix 120. The polymer matrix 120 can be reinjected with a sufficient amount of physical blowing agent 150 to replace the blowing agent 150 that leaked out from the flexible surface 110 during the curing process. In other embodiments, the polymer matrix 120 can be reinjected with a sufficient amount of blowing agent 150 to expand the expandable pellets 100 to about 1.2 to 10 times their original volume.

[0094] The flexible skin 110 is configured to enclose the polymer matrix 120 and the foaming agent 150. At the same time, the flexible skin 110 is configured to be expandable. For example, the flexible skin 110 is configured to expand in accordance with the expansion of the polymer matrix 120. In another embodiment, the flexible skin 110 is configured to expand in accordance with the expansion of the foaming agent 150 and / or the gas released from the foaming agent 150. In one embodiment, the polymer matrix 120 and the foaming agent 150 expand in accordance with the predetermined state change or trigger event described above. As the flexible skin 110 enclosing the polymer matrix 120 and the foaming agent 150 expands, the volume of the expandable pellet 100 increases.

[0095] The flexible skin 110 can be made of a flexible material with excellent stretchability and tear strength to prevent the expandable pellets 100 from tearing when they expand. For example, the tear strength of the flexible skin 110 is 20% higher than that of the polymer matrix 120. In another embodiment, the flexible skin 110 is configured not to tear even when it expands to about 1 to 10 times its original volume. For example, the flexible skin 110 is configured not to tear even when it expands to 1.7 times its original volume.

[0096] The flexible skin 110 includes, for example, flexible materials such as silicone, rubber, polyurethane (PU), and polyethylene (PE). For example, the flexible skin 110 includes thermoplastic elastomers (TPE) such as thermoplastic polyurethane (TPU).

[0097] In some embodiments, the flexible skin 110 comprises a single flexible material. For example, the flexible skin 110 is essentially composed of TPU. In other embodiments, the flexible skin 110 comprises one or more flexible materials, or a combination of one or more flexible materials. For example, the flexible skin 110 comprises TPU or is essentially composed of TPU.

[0098] The flexible skin 110 may include one or more layers. For example, as shown in Figure 5, the flexible skin 110 includes an outer layer 111 and an inner layer 113. For example, the outer layer 111 is the outer layer of the expandable pellet 100, and the inner layer 113 is the layer in contact with the polymer matrix 120. The flexible skin 110 may include one or more functional layers. In some embodiments, at least one of the one or more layers is a functionally assigned layer. For example, the layer is assigned a function that contributes to the roughness, gloss, bondability, texture / feel, and appearance of the flexible skin 110. In one embodiment, the outer layer 111 is assigned a function that allows it to stretch without tearing. In another embodiment, the inner layer 113 is assigned a function that enhances adhesion to the polymer matrix 120.

[0099] For example, the flexible outer layer 110 may be coated with Teflon to reduce adhesion between the expandable pellets 100, and the outer layer 111 may contain PTFE (e.g., Teflon®, commercially available from The Chemours Company in Wilmington, Delaware).

[0100] The flexible skin 110 is configured not to melt during the curing process. Therefore, the melting point of the flexible skin 110 is higher than the maximum curing temperature. For example, the melting temperature of the flexible skin 110 is higher than the curing temperature of the uncured composite part 200. In one embodiment, the melting temperature of the flexible skin 110 is at least 20°F higher than the curing temperature of the uncured composite part 200. For example, if the curing temperature of the composite part is 350°F, the melting temperature of the flexible skin 110 is at least 370°F, and if the curing temperature of the composite part is 250°F, the melting temperature of the flexible skin 110 is at least 270°F.

[0101] In some embodiments, the melting temperature of the flexible skin 110 is approximately 80°F to approximately 800°F. For example, the melting temperature of the flexible skin 110 is approximately 80°F to approximately 270°F, approximately 80°F to approximately 370°F, or approximately 270°F to approximately 370°F.

[0102] The flexible skin 110 restricts the permeation and diffusion of the blowing agent 150 or the gas released from the blowing agent 150 through the flexible skin 110. For example, the flexible skin 110 is substantially impermeable to the blowing agent 150 or the gas released from the blowing agent 150. In one embodiment, the flexible skin 110 is airtight, and the blowing agent 150 (or the gas released from the blowing agent 150) is substantially impermeable to and diffuses through the flexible skin 110.

[0103] In another embodiment, the flexible skin 110 is configured to maintain pressure inside the expandable pellet 100 by controlling the diffusion of the foaming agent 150 (or gas released from the foaming agent 150) through the flexible skin 110. For example, the flexible skin 110 has at least partial permeability to the foaming agent 150 or gas released from the foaming agent 150. The flexible skin 110 is configured to diffuse the foaming agent 150 (or gas released from the foaming agent 150) out of the expandable pellet 100 in response to a predetermined state change, thereby maintaining a predetermined pressure inside the expandable pellet 100.

[0104] In another embodiment, the flexible skin 110 is at least partially permeable to the foaming agent 150, thereby allowing reinjection into the expandable pellet 100 as described above. For example, the flexible skin 110 is configured to allow reinjection of the foaming agent 150 into the polymer matrix 120.

[0105] As shown in Figure 5, in some embodiments, the expandable pellet 100 includes a core 130. The core 130 is configured to facilitate the formation of the expandable pellet 100. In some embodiments, a foaming agent 150 forms the core 130. For example, the core 130 acts as a base to facilitate the formation of a polymer matrix 120 and a flexible skin 110 around the core 130. In other embodiments, the core 130 is configured to facilitate the removal of the expandable pellet 100. For example, the core 130 includes a metal core 140, and the expandable pellet 100 can be easily removed from the system 10 by utilizing magnetism. In other embodiments, the core 130 includes a plurality of metal particles (not shown), and the expandable pellet 100 can be easily removed from the system 10 by utilizing magnetism.

[0106] Core 130 may contain polymer materials such as polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PE), polypropylene (PP), and polyetherimide (PEI).

[0107] The metallic core 140 includes magnetically attracted materials such as Fe, Co, and Ni. In other embodiments, at least one of the core 130 or the core 140 includes a ferromagnetic material. In some embodiments, the metallic core 140 includes metallic particles integrated into the polymer material forming the core 130.

[0108] Each expandable pellet 100 has an average particle size of approximately 0.5 mm to approximately 10 mm. For example, the average particle size of the expandable pellet 100 is approximately 1 mm to approximately 5 mm, approximately 1.5 mm to approximately 2.5 mm, or approximately 2 mm.

[0109] Figure 6 shows a method for curing composite material components according to one embodiment. Figure 6 shows an example of a method that may be used in the systems 10 and / or 20 described above, for example, as shown in Figures 1 to 5. Therefore, the following description will refer to the various components shown in Figures 1 to 5.

[0110] As shown in Figure 6, in the method 800 for curing the composite material part 200, first, in process 810, the uncured composite material part 200 is placed on a mandrel 300. For example, the uncured composite material part 200 is placed between the upper mandrel 310 and the lower mandrel 320 that make up the mandrel 300. The uncured composite material part 200 may also be molded by the mandrel 300. The mandrel 300 may also be configured to heat the uncured composite material part 200 during the curing process. In some embodiments, the uncured composite material part 200 is placed in a mold 450 that houses the mandrel 300. The mold 450 houses a plurality of expandable pellets 100 and is configured to apply positive pressure to the uncured composite material part 200 when these plurality of expandable pellets 100 expand. The mold 450 is not required to be airtight.

[0111] Process 820 includes placing a plurality of expandable pellets 100 in an uncured composite component 200. The plurality of expandable pellets 100 are, for example, placed around the uncured composite component 200. In other embodiments, the uncured composite component 200 defines one or more internal cavities 250, and the plurality of expandable pellets 100 are placed within the one or more internal cavities 250.

[0112] Each expandable pellet 100 includes a blowing agent 150, a polymer matrix 120 that holds the blowing agent 150, and a flexible skin 110 that encloses the polymer matrix 120 and the blowing agent 150. In some embodiments, a plurality of expandable pellets 100 use the same material for the blowing agent 150, the same material for the polymer matrix 120, and / or the same material for the flexible skin 11 in all pellets. In other embodiments, the plurality of expandable pellets 100 can be made of different materials for the blowing agent 150, different materials for the polymer matrix 120, and / or different materials for the flexible skin 110. The flexible skin 110 has at least partial permeability to the blowing agent 150 or gases released from the blowing agent 150. The flexible skin 110 controls the expansion of the expandable pellet 100 by limiting the leakage of the blowing agent 150 or gases released from the blowing agent 150.

[0113] The process 830 includes expanding a plurality of expandable pellets 100. In some embodiments, the plurality of expandable pellets 100 are configured to expand in response to a predetermined state change or trigger event. For example, the plurality of expandable pellets 100 are configured to expand in response to a temperature change.

[0114] Process 840 includes applying positive pressure to the uncured composite part 200. For example, when the multiple expandable pellets 100 expand, they apply positive pressure to the uncured composite part 200. In some embodiments, as the multiple expandable pellets 100 expand, they deform at least partially, thereby causing the multiple expandable pellets 100 to fill in the gaps between the expandable pellets 100 particles, between the expandable pellets 100 and the inner or outer surface of the uncured composite part 200, and / or between the expandable pellets 100 and the mold 450 or mandrel 300.

[0115] Process 850 includes curing the uncured composite component 200. For example, the uncured composite component 200 is cured by applying a combination of heat and pressure set to cure the composite component 200. In some embodiments, the uncured composite component 200 is cured by applying a predetermined curing temperature profile and consolidation pressure profile to the uncured composite component 200. In some embodiments, the uncured composite component 200 is cured by applying positive pressure to the uncured composite component 200 with a plurality of expandable pellets 100. The expandable pellets 100 are configured to remain expanded throughout the curing cycle. For example, the expandable pellets 100 are configured to remain expanded for at least 5 minutes, at least 10 minutes, at least 20 minutes, at least 1 hour, and at least 2 hours. In some embodiments, the mandrel 300 is configured to apply the curing temperature to the uncured composite component 200. In some embodiments, the mandrel 300 is configured to apply consolidation pressure to the uncured composite component 200. In other embodiments, a plurality of expandable pellets 100 are configured to apply consolidation pressure to the uncured composite component 200. In some embodiments, the consolidation pressure applied to the uncured composite component 200 is based solely on the expandable pellets 100 as the pressure source.

[0116] Process 860 includes removing a plurality of expandable pellets 100. For example, the plurality of expandable pellets 100 have magnetic nuclei and can be removed using magnetism. In other embodiments, the plurality of expandable pellets 100 are physically removed, for example, by a vacuum hose or a vacuum pump. In some embodiments, the plurality of expandable pellets 100 shrink before being removed. The plurality of expandable pellets 100 are configured to shrink after a predetermined state change or trigger event has disappeared. For example, if the plurality of expandable pellets 100 have expanded in response to a temperature change, these expandable pellets 100 will either collapse when cooled or elastically return to their original size and shape. In other embodiments, the plurality of expandable pellets 100 will maintain their expanded state by plastic deformation even after cooling. In some embodiments, shrinking the expanded plurality of expandable pellets 100 includes cooling these expandable pellets 100.

[0117] Process 870 includes removing the cured composite part 200. After the curing process, the cured composite part 200 is removed from the mandrel 300 in process 860.

[0118] In some embodiments, method 800 further includes reinjecting the multiple expandable pellets 100 in process 880. For example, since the flexible skin 110 of the multiple expandable pellets 100 is at least partially permeable to the foaming agent 150, when the multiple expandable pellets 100 are placed in a container containing high-pressure foaming agent 150, the foaming agent 150 can permeate through the flexible skin 110 and diffuse into the interior of the expandable pellets 100, allowing the foaming agent 150 to be reinjected. Method 800 then includes reusing the expandable pellets 100 in process 890. For example, after removing the cured composite part 200, at least one of the multiple expandable pellets 100 is shrunk, removed, reinjected, and again used to cure another uncured composite part 200 in process 820, as described in processes 860 to 880 above.

[0119] The embodiments of this disclosure are useful for a variety of applications, and are particularly useful in the transportation industry, including aerospace, marine, automotive, and other applications where hardening of composite components is desirable. Accordingly, the embodiments of this disclosure can be used in connection with the aircraft manufacturing and use method 1000 shown in Figure 7 and the aircraft 2000 shown in Figure 8, as described below with reference to Figures 7 and 8. As a pre-production process, method 1000 includes specification and design 1102 of the aircraft 2000 and material procurement 1104. During production, the manufacturing of components / small assemblies 1106 and system integration 1108 of the aircraft 2000 are carried out. Subsequently, the aircraft 2000 undergoes certification and delivery 1110 and enters service 1112. During the customer's service period, the aircraft 2000 is incorporated into routine maintenance and upkeep 1114, including improvements, reconfiguration, and modifications.

[0120] Each process of Method 1000 may be performed or implemented by a system integrator, a third party, and / or an operator (e.g., a customer). For illustrative purposes, the system integrator may include, but is not limited to, several aircraft manufacturers and major system subcontractors. The third party may include, but is not limited to, several sellers, subcontractors, and suppliers. The operator may be an airline, leasing company, military organization, service organization, etc.

[0121] The aircraft 2000 manufactured by Method 1000 comprises a fuselage 2115 having a plurality of systems 2118 and interior 2120, as shown in Figure 8. Examples of systems 2118 include one or more of the propulsion system 2122, electrical system 2124, hydraulic system 2126, and environmental system 2128. It may also include any number of other systems. While an example from the aerospace industry has been given, the principles of this disclosure are applicable to other industries such as the marine and automotive industries.

[0122] Furthermore, this disclosure also includes embodiments as specified below.

[0123] Note 1. A system for curing a composite material component, comprising: a mandrel configured to receive and support an uncured composite material component; a plurality of expandable pellets arranged on the uncured composite material component; and a mold configured to house the mandrel, the uncured composite material component, and the plurality of expandable pellets, wherein the plurality of expandable pellets are configured to expand in accordance with a change of state or trigger event to apply positive pressure to the uncured composite material component, and each of the plurality of expandable pellets comprises a foaming agent, a polymer matrix configured to hold the foaming agent, and a flexible skin configured to enclose the polymer matrix and the foaming agent, wherein the flexible skin is at least partially permeable to the foaming agent or gases released from the foaming agent.

[0124] Note 2. The system according to Note 1, wherein the flexible outer layer is configured to control the expansion of each of the plurality of expandable pellets.

[0125] Appendix 3. The system according to Appendix 2, wherein controlling the expansion of each of the plurality of expandable pellets includes at least one of expanding each of the plurality of expandable pellets and maintaining the expanded state of each of the plurality of expandable pellets.

[0126] Note 4. The system according to Note 3, wherein the expanded state is maintained for a duration of at least 20 minutes, at least 30 minutes, at least 40 minutes, at least 60 minutes, at least 2 hours, or at least 5 hours.

[0127] Note 5. The system according to Note 3 or 4, wherein the foaming agent releases gas in response to a change in state or a trigger event, and the rate at which the gas is released from the foaming agent in response to the change in state or the trigger event exceeds the rate at which the gas leaks through the flexible skin so that each of the plurality of expandable pellets expands or maintains an expanded state.

[0128] Note 6. The system according to any one of Notes 3 to 5, wherein the polymer matrix releases the foaming agent in response to a change of state or a trigger event, and the rate at which the foaming agent is released from the polymer matrix in response to the change of state or a trigger event exceeds the rate at which the foaming agent leaks through the flexible surface so that each of the plurality of expandable pellets expands or maintains an expanded state.

[0129] Note 7. The system according to any one of Notes 3 to 6, wherein the foaming agent expands in volume in response to a change in state or a trigger event, and the rate at which the foaming agent leaks through the flexible surface is such that each of the plurality of expandable pellets expands or maintains an expanded state.

[0130] Note 8. The polymer matrix is ​​a system according to any one of Notes 1 to 7, comprising a thermoplastic polymer.

[0131] Note 9. The system according to Note 8, wherein the polymer matrix comprises at least one of polyurethane (PU), polypropylene (PP), polycarbonate (PC), polyetherimide (PEI), polystyrene (PS), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), (poly)methyl methacrylate (PMMA), nylon, and vinyl.

[0132] Note 10. The flexible skin is a system according to any one of the notes 1 to 9, comprising a thermoplastic elastomer (TPE).

[0133] Note 11. The system according to any one of Notes 1 to 10, wherein the flexible skin comprises at least one of silicone, rubber, polyurethane (PU), and polyethylene (PE).

[0134] Appendix 12. The system according to any one of the appendices 1 to 11, wherein the blowing agent comprises at least one of a chemical blowing agent and / or a physical blowing agent.

[0135] Note 13. The system according to Note 12, wherein the chemical blowing agent is configured to release gas in accordance with the state change or trigger event.

[0136] Note 14. The system according to Note 13, wherein the chemical blowing agent comprises at least one of isocyanate, azodicarbonamide, hydrazine, toluenesulfonyl semicarbazide, sodium bicarbonate, or citric acid.

[0137] Note 15. The system according to Note 12, wherein the physical blowing agent comprises a thermally expandable physical agent.

[0138] Appendix 16. The system according to Appendix 15, wherein the physical blowing agent comprises at least one of an inert, non-flammable gas, a flammable gas, a hydrocarbon, or water vapor.

[0139] Note 17. The system according to Note 12, wherein the foaming agent further comprises a functional additive that further promotes foaming.

[0140] Appendix 18. The system according to any one of Appendix 1 to 17, wherein the flexible skin is configured to allow reinjection of a foaming agent into the polymer matrix.

[0141] Note 19. The system described in any of Notes 10 to 18, wherein the state change or trigger event includes one or more of the following: a temperature change, a pressure change, a chemical reaction, or an input of radiant energy.

[0142] Note 20. A method for curing a composite material part, comprising: placing an uncured composite material part on a mandrel; placing a plurality of expandable pellets on the uncured composite material part; expanding the plurality of expandable pellets; applying positive pressure to the uncured composite material part; and curing the uncured composite material part, wherein each of the plurality of expandable pellets comprises a foaming agent; a polymer matrix configured to hold the foaming agent; and a flexible skin configured to enclose the polymer matrix and the foaming agent, wherein the flexible skin is at least partially permeable to the foaming agent or gas released from the foaming agent, and the flexible skin is configured to control the expansion of each of the plurality of expandable pellets by limiting the leakage of the foaming agent or gas released from the foaming agent.

[0143] Appendix 21. The method according to Appendix 20, further comprising reinjecting the plurality of expandable pellets and reusing the expandable pellets.

[0144] Note 22. An expandable pellet used for curing composite components, comprising a foaming agent, a polymer matrix configured to hold the foaming agent, and a flexible skin configured to enclose the polymer matrix and the foaming agent, wherein the flexible skin is at least partially permeable to the foaming agent or gases released from the foaming agent, and the flexible skin is configured to control the expansion of the expandable pellet.

[0145] The systems and methods illustrated herein can be employed in any one or more stages of the aircraft manufacturing and operation method 1000. For example, the production or manufacture of parts and small assemblies during the operation of aircraft 2000 can be carried out in the same manner as the production of parts and small assemblies in manufacturing process 1106. Furthermore, one or more embodiments of the apparatus, embodiments of the method, or combinations thereof can be employed, for example, in manufacturing processes 1106 and 1108, thereby significantly improving, for example, the assembly speed and cost of aircraft 2000. Similarly, one or more embodiments of the apparatus, embodiments of the method, or combinations thereof can be employed during the operation of aircraft 2000, for example, maintenance and servicing 1114, but not limited to these.

[0146] Figures 7 and 8 illustrate aircraft and the manufacture and use of aircraft, but this disclosure is not limited thereto. The systems and methods of this disclosure can be used for spacecraft, satellites, submarines, surface ships, tanks, trucks, power plants, and any other suitable type of subject matter.

[0147] This disclosure has been described with reference to exemplary embodiments. While several embodiments have been illustrated and described, it will be apparent to those skilled in the art that these embodiments can be modified without departing from the principles and gist of the above description. Such modifications and changes should all be construed as being incorporated into this disclosure, insofar as they fall within the scope of the appended claims and their equivalents.

Claims

1. A system for curing composite material parts, A mandrel configured to receive and support an uncured composite material component, Multiple expandable pellets arranged in the uncured composite material component, The system comprises the mandrel, the uncured composite material component, and a mold configured to accommodate the plurality of expandable pellets, The plurality of expandable pellets are configured to expand in the curing process in accordance with a change of state or trigger event, thereby applying positive pressure to the uncured composite material component. Each of the above-mentioned plurality of expandable pellets is Foaming agent and A polymer matrix configured to hold the foaming agent, It includes the polymer matrix and a flexible skin configured to enclose the foaming agent, The flexible skin of the system has at least partial permeability to the foaming agent or the gas released from the foaming agent.

2. The system according to claim 1, wherein the flexible outer layer is configured to control the expansion of each of the plurality of expandable pellets by limiting the leakage of the foaming agent or gas released from the foaming agent.

3. The system according to claim 2, wherein controlling the expansion of each of the plurality of expandable pellets includes at least one of expanding each of the plurality of expandable pellets and maintaining the expanded state of each of the plurality of expandable pellets.

4. The system according to claim 3, wherein the expanded state is maintained for a duration of at least 20 minutes, at least 30 minutes, at least 40 minutes, at least 60 minutes, at least 2 hours, or at least 5 hours.

5. The system according to claim 3 or 4, wherein the foaming agent releases gas in response to a change in state or a trigger event, and the rate at which the gas is released from the foaming agent in response to the change in state or the trigger event exceeds the rate at which the gas leaks through the flexible surface so that each of the plurality of expandable pellets expands or maintains an expanded state.

6. The system according to any one of claims 3 to 5, wherein the polymer matrix releases the foaming agent in response to a change of state or a trigger event, and the rate at which the foaming agent is released from the polymer matrix in response to the change of state or the trigger event exceeds the rate at which the foaming agent leaks through the flexible surface so that each of the plurality of expandable pellets expands or maintains an expanded state.

7. The system according to any one of claims 3 to 6, wherein the foaming agent expands in volume in response to a change in state or a trigger event, and the rate at which the foaming agent leaks through the flexible surface is such that each of the plurality of expandable pellets expands or maintains an expanded state.

8. The polymer matrix comprises a thermoplastic polymer, and optionally, the polymer matrix comprises at least one of polyurethane (PU), polypropylene (PP), polycarbonate (PC), polyetherimide (PEI), polystyrene (PS), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), (poly)methyl methacrylate (PMMA), nylon, and vinyl, according to any one of claims 1 to 7. The system described.

9. The system according to any one of claims 1 to 8, wherein the flexible skin comprises a thermoplastic elastomer (TPE), and optionally, the flexible skin comprises at least one of silicone, rubber, polyurethane (PU), and polyethylene (PE).

10. The system according to any one of claims 1 to 9, wherein the blowing agent comprises at least one of a chemical blowing agent and / or a physical blowing agent.

11. The system according to claim 10, wherein the chemical blowing agent is configured to release gas in accordance with the state change or trigger event.

12. The system according to claim 11, wherein the chemical blowing agent comprises at least one of isocyanate, azodicarbonamide, hydrazine, toluenesulfonyl semicarbazide, sodium bicarbonate, or citric acid.

13. The system according to claim 10, wherein the physical blowing agent comprises a thermally expandable physical agent.

14. The system according to claim 13, wherein the physical blowing agent comprises at least one of an inert, non-flammable gas, a flammable gas, a hydrocarbon, or water vapor.

15. The system according to any one of claims 10 to 14, further comprising a functional additive that further promotes foaming of the foaming agent.

16. The system according to any one of claims 1 to 15, wherein the flexible skin is configured to allow reinjection of a foaming agent into the polymer matrix.

17. The system according to any one of claims 10 to 16, wherein the state change or trigger event includes one or more of a temperature change, a pressure change, a chemical reaction, or an input of radiant energy.

18. A method for curing composite material parts, Placing uncured composite material parts on a mandrel, The process involves placing multiple expandable pellets on the aforementioned uncured composite material component, Expanding the aforementioned plurality of expandable pellets, Applying positive pressure to the aforementioned uncured composite material component, This includes curing the aforementioned uncured composite material component, Each of the above-mentioned plurality of expandable pellets is Foaming agent and A polymer matrix configured to hold the foaming agent, It includes the polymer matrix and a flexible skin configured to enclose the foaming agent, The flexible skin has at least partial permeability to the foaming agent or the gas released from the foaming agent. A method wherein the flexible outer layer is configured to control the expansion of each of the plurality of expandable pellets by limiting the leakage of the foaming agent or the gas released from the foaming agent.

19. Furthermore, the multiple expandable pellets are reinjected, The method according to claim 18, comprising reusing the expandable pellets.

20. An expandable pellet used for curing composite material parts, Foaming agent and A polymer matrix configured to hold the foaming agent, It includes the polymer matrix and a flexible skin configured to enclose the foaming agent, The flexible skin has at least partial permeability to the foaming agent or the gas released from the foaming agent. The flexible outer layer is configured to control the expansion of the expandable pellet by limiting the leakage of the foaming agent or the gas released from the foaming agent. Expandable pellets.

Images