3D node-winding-based ultralight, high-strength continuous-fiber composite

Abstract

According to one embodiment of the present invention, the present invention relates to a modular coupling structure using an ultralight, high-strength lattice continuous-fiber composite, and to a method for manufacturing same.

Description

3D Node Winding-Based Ultralight, High-Strength Continuous Fiber Composite

[0001] The present invention relates to a structure made of a composite material, and more specifically, to the development of a new three-dimensional structure.

[0002]

[0003] In structural development fields where material lightweighting is key, such as the machinery, aerospace, automotive, and robotics industries, balancing strength and weight in material selection has long been a critical technical challenge.

[0004] For example, titanium alloys (such as Ti-6Al-4V) provide excellent mechanical performance with a tensile strength of 900 to 1,200 MPa and also have excellent corrosion resistance, but their density is about 4.5 g / cm³, which limits their ability to lighten structures. This restricts design freedom, particularly in systems where mass leads directly to performance degradation, such as aircraft, robotic arms, and drones.

[0005] Conversely, plastic materials, such as PLA, are very lightweight with a density of 1.25 g / cm³ and have high compatibility with 3D printing (FDM) technology, allowing for the rapid and easy fabrication of shapes. However, general plastics have low tensile strength of around 50 to 60 MPa and lack resistance to heat and shock, which limits their use in environments with heavy structural loads.

[0006] Carbon fiber reinforced plastic (CFRP) is a material introduced to overcome these limitations. In particular, composites utilizing continuous carbon fibers possess a maximum tensile strength of 3,500 MPa and a density of approximately 1.6 g / cm³, offering an excellent strength-to-weight ratio that makes them suitable for applications such as aircraft, supercars, and space structures. However, since most conventional CFRPs follow a two-dimensional planar lamination method (e.g., autoclave curing after prepreg lamination), there are limitations in realizing highly porous structures with hollow interiors or complex three-dimensional shapes. Furthermore, mold and die design are essential, resulting in high production costs and significant equipment burdens.

[0007] In particular, although CFRP is strong in the tensile direction, stress discontinuities occur at fiber cutting and interlayer boundaries, and fiber buckling and delamination are prone to occur in a compressive environment due to the interfacial strength between the fibers and the resin and the brittleness of the resin itself.

[0008] For this reason, the application of CFRP with lattice structures that are hollow inside while maintaining strength has recently been attempted. These structures theoretically have the advantage of increasing the strength of the entire structure and reducing its weight by distributing the load along the lattice path.

[0009] However, existing manufacturing methods for high-porous structures also have the following serious limitations. First, while assembling separately molded lattice parts using bolt fastening or snap-fit ​​methods appears simple and reusable, the structural disconnection at the joints leads to stress concentration and a high risk of breakage. In particular, snap-fit ​​structures rely on artificial press-fitting, resulting in low precision and significant durability degradation during repeated assembly. Next, while 3D-printed lattice structures excel in shape realization, the inherent characteristics of the FDM method result in weak interlayer adhesion, limiting strength and making them difficult to apply to structures subjected to actual heavy loads. Since most printing materials are thermoplastics, they are vulnerable to long-term loads or temperature changes and lack structural integrity. Conventional manual methods for manufacturing CFRP lattices mostly involve inserting or cross-arranging cut prepregs or carbon tubes and bonding them; this method suffers from low manual precision and is unsuitable for repetitive production. Furthermore, the requirement for molds or limitations in realizing porous shapes pose difficulties for large-scale structures or modularization. In other words, most existing composites are limited to a single reinforcing fiber family centered on carbon fibers, making it difficult to selectively apply various fiber families and material combinations, such as metal fibers and natural fibers, depending on the structural application.

[0010] Ultimately, these technologies have clear limitations in various aspects, such as mechanical strength, compressive strength, precision, productivity, and geometric degrees of freedom.

[0011]

[0012] The present invention aims to overcome the limitations of manual work and simultaneously secure structural repeatability and precision through a fiber alignment fixing mechanism utilizing a 3D printed support, as a precise manufacturing method capable of realizing a three-dimensional lattice or porous structure without structural discontinuity based on a single continuous carbon fiber.

[0013] Accordingly, we aimed to develop an integrated process that overcomes the structural limitations of existing 2D planar laminated CFRPs, enables fabrication without molds, adhesives, or fasteners, and allows for the integration of composite materials after resin impregnation. By applying a multi-type node support structure to ensure tension retention and mechanical fastening stability, we provide a 3D node winding platform technology that connects a simple planar structure to a spatial three-dimensional structure, thereby realizing a lattice structure with high strength, high precision, and high durability. Furthermore, through a design method that enables modularization and stacking, it is expandable into structures of various sizes and shapes, allowing for multi-field applications such as robotics, UAVs, medical, and construction. Additionally, by designing a structure that simultaneously satisfies improved compressive strength and lightweighting, we sought to compensate for the weaknesses of existing CFRPs and ensure structural reliability.

[0014]

[0015] In order to solve the aforementioned problem, one aspect of the present invention proposes a new manufacturing process and structural design that overcomes the limitations of the existing 2D planar lamination method of CFRP by using a 3D lattice or porous structure, and enables the production of a high-strength and ultra-lightweight structure.

[0016] According to one embodiment of the present invention, a lattice high-strength bonding structure may comprise: a plurality of core supports; a node support connected to the ends of the core supports to form a connection between the plurality of core supports; a continuous fiber material provided to be continuously connected without interruption along the outer surface of a three-dimensional structure composed of the core supports and the node support; and a resin material forming a coating on the core supports, the node support, and the continuous fiber material.

[0017] According to one embodiment, one or more of the core support and node support may comprise one or more selected from the group consisting of PLA, ABS, PETG, TPU, Nylon, PC, and ASA, which are 3D printing-based thermoplastic resin-based filaments; and one or more selected from the group consisting of PVA and BVOH, which are water-soluble support filaments.

[0018] According to one embodiment, the core support may include a plurality of core branches extending in a rod shape from the center to form a vertical structure relative to each other.

[0019] According to one embodiment, the node support may include a first type of node support comprising a plurality of node branches extending from the center to form a vertical structure between them; and a second type of node support having a clip-lock structure that is difficult to detach in the reverse direction after being inserted by pressing in one direction.

[0020] According to one embodiment, the node branch portion of the first type node support has a smaller diameter compared to the core branch portion, and the end of the node branch portion is inserted into the end of the core branch portion, and the core supports may be connected to form a single unit cell.

[0021] According to one embodiment, in the unit cell, the center of the core support becomes the body center of the BCC (Body-Centered Cubic) structure, and the center of the first type node support forms the outer edge of the BCC structure to form a unit cell unit.

[0022] According to one embodiment, the unit cell may crystallographically have a lattice shape among SC, BCC, and FCC structures.

[0023] According to one embodiment, the core support and the second type node support are connected to form a single two-dimensional unit cell, and the two-dimensional unit cell may be configured to be continuously expanded into a three-dimensional node structure.

[0024] According to one embodiment, the unit cell may be optionally removable or retainable.

[0025] According to one embodiment, the continuous fiber material may comprise one or more reinforcing fibers selected from the group consisting of carbon fiber, glass fiber, basalt fiber, ceramic fiber, silicon carbide fiber, alumina fiber, aramid fiber, Kevlar fiber, graphite fiber, PBO fiber, PEEK fiber, PPS fiber, and metal fiber; and one or more non-reinforcing fibers selected from the group consisting of polyester, nylon, polyurethane, polyethylene, polypropylene, yarn fiber, cotton fiber, flax fiber, bamboo fiber, silk fiber, and polylactic acid fiber.

[0026] According to one embodiment, the resin material comprises one or more selected from the group consisting of irreversible thermosetting resins such as epoxy, vinyl ester, unsaturated polyester, phenolic resin, melamine, and urea resin; and the group consisting of reversible thermosetting resins such as Diels-Alder-based resin, Imine-based resins, urea / urethane dynamic resins, and vitrimers, and may comprise a low viscosity resin with a viscosity of 300 to 500 cps.

[0027] According to one embodiment, the lattice high-strength bonding structure may have a three-dimensional structure.

[0028]

[0029] According to another embodiment of the present invention, a method for manufacturing a lattice high-strength bonding structure may comprise the steps of: preparing a core support including a core branch portion and a node support including a node branch portion; forming a unit cell lattice structure by connecting the node branch portion of the node support to the core branch portion of the core support; arranging a continuous fiber material along the outer surface of the core support and the node support; and impregnating the unit cell, on which the continuous fiber material is wound, with a resin material to form a coating on the surface of the unit cell.

[0030] According to one embodiment, the step of winding the continuous fiber material may include: designing one or more single paths capable of covering the outer surface of a support under conditions that the continuous fiber material is not broken in the unit cell; and winding the continuous fiber material along the one or more designed single paths.

[0031] According to one embodiment, the method may further include a step of winding the continuous fiber material; and subsequently, a step of tensioning the continuous fiber material.

[0032] According to one embodiment, the resin material may further include the step of drying for 2 to 24 hours after impregnating the unit cell.

[0033] According to one embodiment, the method may further include a step of forming a coating on the surface of the unit cell; and subsequently, a porous lightweighting step of selectively removing the unit cell.

[0034]

[0035] The lattice-based bonding structure proposed in the embodiment of the present invention is a composite material structure that secures precision in fiber alignment through a unit cell-based module design combination combining a 3D printed support fabricated by additive manufacturing and continuous carbon fibers, and possesses mechanical integrity through a low-viscosity resin impregnation and curing process.

[0036] In particular, the lattice-based high-strength bonding structure proposed in the embodiment of the present invention can be applied as a replacement for existing high-density CFRP panels or as a reinforcing material due to its ability to maintain porosity and sufficient mechanical support within the structure, as lightweighting of structures in the aerospace and mobility industries is directly linked to performance, fuel efficiency, and safety.

[0037] Lattice-based bonding structures manufactured according to the embodiments proposed in this invention have the advantage of realizing structures with overwhelmingly higher strength and lower relative density compared to existing structures. By including multiple types of node supports, the problems of stress concentration and fastening instability in existing lattice structures can be resolved, and the tensile strength of continuous fibers and structural stability during repeated assembly can be simultaneously secured. These structural features reduce the risk of failure at the bonding part and improve the compressive and tensile strength of the entire structure compared to existing adhesive or simple fastening lattice structures. Furthermore, this invention provides a manufacturing method in the form of a general-purpose platform capable of accommodating curved surfaces and multi-layered structures, configured so that a two-dimensional unit cell-based structure can be expanded using a three-dimensional node winding method, thereby significantly improving shape freedom, space, and material utilization. Additionally, it is designed to allow the use of reinforced fibers, non-reinforced fibers, or combinations of fibers, enabling the realization of composite structures optimized according to the characteristics of specific applications.

[0038] In robotics and precision machine systems, stiffness, precision, and weight must be considered simultaneously at the small part level, so as a modular ultra-lightweight structure, it can be effectively applied to multi-joint mechanism parts such as robot arms, fingers (grippers), and joint housings.

[0039] In the unmanned aerial vehicle (UAV) and drone industry, extreme lightweighting of structures to maximize battery efficiency is essential, while securing mechanical strength capable of withstanding loads during flight is also critical. The lattice high-strength bonding structure of the present invention is suitable for lightweight structural configurations such as frames, wing reinforcements, and airframe housings.

[0040] In addition, in fields such as medical devices and wearable devices that are worn closely on the human body and have complex usage environments, it is important for the structure to possess both flexibility and strength, and to be able to realize a free shape. The lattice high-strength bonding structure of the present invention has a high degree of design freedom and does not require mold removal, so it can be utilized in customized wearable structures.

[0041] This provides an integrated composite manufacturing platform centered on node-based winding, moving away from traditional composite molding methods such as RTM, hot press, autoclave, and AFP. It offers numerous advantages, including simplification of the manufacturing process, cost reduction, and time savings, as it enables the formation of three-dimensional structures without molds. It is an application technology that presents a new three-dimensional node winding design paradigm and process system for composite manufacturing technology.

[0042]

[0043] FIG. 1 is an image showing a schematic diagram of a first type and a second type node support according to one embodiment of the present invention.

[0044] FIG. 2 is an image showing a schematic diagram of a 2D-based internal winding and an external winding according to an embodiment of the present invention.

[0045] FIG. 3 is an image showing various topology configurations according to one embodiment of the present invention.

[0046] FIG. 4 is a schematic diagram showing a lattice high-strength bonding structure based on a single continuous fiber path according to one embodiment of the present invention, and is an image showing a structure with some supports included in the structure removed.

[0047] FIG. 5 is an image showing an example of the manufacturing steps of a lattice high-strength bonding structure according to one embodiment of the present invention.

[0048] FIG. 6 is a schematic diagram showing the structures of various unit cells according to one embodiment of the present invention.

[0049] FIG. 7 is a schematic diagram illustrating the process of designing a single path of a continuous fiber material provided along the outer surface in an overall structure composed of a plurality of unit cells according to one embodiment of the present invention.

[0050] FIG. 8 is a schematic diagram showing each step of a method for manufacturing a lattice high-strength bonded structure according to one embodiment of the present invention.

[0051] FIG. 9 is a graph showing the strength and relative density ratio according to the structure (SC, FCC) of a three-dimensional structure manufactured according to one embodiment of the present invention, compared with the same structure (SC, FCC) manufactured with conventional materials.

[0052] FIG. 10 is a sample photograph of a high-strength bonding structure in which some support members are selectively removed within a lattice high-strength bonding structure according to one embodiment of the present invention.

[0053] FIG. 11 is a graph showing the results of comparing deformation behavior and compressive strength according to the configuration of a lattice high-strength bonding structure according to one embodiment of the present invention.

[0054] FIG. 12 is an image showing a lattice high-strength bonding structure formed by stacking and expanding unit cells according to one embodiment of the present invention.

[0055] FIG. 13 is an image and graph showing FEA results according to the configuration of a unit cell according to one embodiment of the present invention.

[0056] FIG. 14 is a graph showing the mechanical properties of a lattice high-strength bonded structure according to one embodiment of the present invention.

[0057] FIG. 15 is a graph of the electrical characteristics of a lattice high-strength bonding structure according to one embodiment of the present invention.

[0058] FIG. 16 is an image illustrating the application of a lattice high-strength bonding structure according to one embodiment of the present invention.

[0059]

[0060] The embodiments of the present invention are illustrative for the purpose of explaining the technical concept of the present invention. The scope of rights according to the present invention is not limited to the embodiments presented below or the specific description thereof.

[0061] All technical and scientific terms used in this invention, unless otherwise defined, have the meaning generally understood by those skilled in the art to which this invention pertains. All terms used in this invention are selected for the purpose of further explaining this invention and are not selected to limit the scope of rights according to this invention.

[0062] Expressions such as "comprising," "having," "having," etc. used in the present invention should be understood as open-ended terms implying the possibility of including other embodiments, unless otherwise stated in the phrase or sentence containing such expressions.

[0063] Unless otherwise stated, singular expressions described in the present invention may include the meaning of the plural form, and this applies likewise to singular expressions described in the claims.

[0064] Hereinafter, the present invention will be described in detail with reference to the attached drawings, and embodiments of the present invention will be described. Furthermore, in the description of the embodiments below, the description of identical or corresponding components may be omitted. However, even if a description of a component is omitted, it is not intended that such component is not included in any embodiment. Also, the present invention is not limited to these embodiments and drawings.

[0065] After researching methods to solve the conventional problems as described above, the inventors proposed the ultralight, high-strength lattice continuous fiber composite and modular structure and the method for manufacturing the same as proposed in the embodiments of the present invention, and completed the present invention by applying them to an actual research environment.

[0066] According to one embodiment of the present invention, a lattice high-strength bonding structure may comprise: a plurality of core supports; a node support connected to the ends of the core supports to form a connection between the plurality of core supports; a continuous fiber material provided to be continuously connected without interruption along the outer surface of a three-dimensional structure composed of the core supports and the node support; and a resin material forming a coating on the core supports, the node support, and the continuous fiber material.

[0067] Conventional CFRP laminate-based structures had limitations in strength, safety, and design freedom due to fragmented fiber paths. A three-dimensional lattice structure comprising multiple core supports and connecting node supports utilizing 3D node-based winding technology is designed so that continuous fibers are wound seamlessly along the outer surfaces, rather than through simple bonding or fastening methods. This design overcomes limitations such as discontinuities in stress transfer paths compared to existing structures. This structure minimizes stress concentration and ensures that the entire load is evenly distributed along the fiber paths.

[0068] According to one embodiment, one or more of the core support and node support may comprise one or more selected from the group consisting of PLA, ABS, PETG, TPU, Nylon, PC, and ASA, which are 3D printing-based thermoplastic resin-based filaments; and one or more selected from the group consisting of PVA and BVOH, which are water-soluble support filaments.

[0069] According to one embodiment, the core support may include a plurality of core branches extending in a rod shape from the center to form a vertical structure relative to each other.

[0070] The support formed via 3D printing functions as a structural frame that guides the winding path of continuous fibers and acts as a node anchor, allowing for design flexibility. Additionally, core supports and / or node supports made of thermoplastic resins such as PLA can be pre-fabricated using the FDM method and deposited at specific locations within the structure. Meanwhile, when using water-soluble support filaments to manufacture structures with more complex shapes or precision models, the support can be automatically dissolved and removed—for example, by immersing it in a mild NaOH solution after curing—enabling the production of complex and precise lattice structures without damage. Furthermore, the node support can be modified to be fixed in place after being inserted to one side, and the material of the 3D printed support can be selectively adjusted according to the purpose.

[0071] According to one embodiment, the node support may include a first type of node support comprising a plurality of node branches extending from the center to form a vertical structure between them; and a second type of node support having a clip-lock structure that is difficult to detach in the reverse direction after being inserted by pressing in one direction.

[0072] The core support can be arranged to form a three-dimensional spatial arrangement interconnected by the node support. The first type of node support has a shape similar to the core support and has a multi-directional radial connection structure, and the second type of node support is designed with a clip-lock structure that is fastened when inserted in one direction and prevents reverse separation, thereby maintaining the tension of the fiber. The node support is shown in FIG. 1.

[0073] The first type of node support may have the same shape as the core support but be smaller in size, and the second type of node support may not have the same shape as the core support but may be similar in size to or smaller than the first type of node support. The size of the node support is adjustable.

[0074] The above supports are lighter than conventional bolt fastening methods and can serve to stably fix the position of the continuous fiber material provided on the outer surface of the supports.

[0075] According to one embodiment, the node branch portion of the first type node support has a smaller diameter compared to the core branch portion, and the end of the node branch portion is inserted into the end of the core branch portion, and the core supports may be connected to form a single unit cell.

[0076] If necessary, the core branch and the node branch may also be detachable. The first type of node support is formed in a multi-faceted direction centered on the core support, and has a structure in which multiple core supports are connected to each other in a form that allows for inter-face joining.

[0077] According to one embodiment, in the unit cell, the center of the core support becomes the body center of the BCC (Body-Centered Cubic) structure, and the center of the first type node support forms the outer edge of the BCC structure to form a unit cell unit.

[0078] This allows the structural geometric form to be designed as a unit cell of a lattice structure, satisfying the geometric conditions of a structure where each cell can efficiently distribute the load.

[0079] According to one embodiment, the unit cell may crystallographically have a lattice shape among SC, BCC, and FCC structures.

[0080] The overall structure is formed by the repetition of unit cells, and the unit cells are designed as modules that allow for stacking, interlocking, and modular growth as needed.

[0081] According to one embodiment, the core support and the second type node support are connected to form a single two-dimensional unit cell, and the two-dimensional unit cell may be configured to be continuously expanded into a three-dimensional node structure.

[0082] The Type 2 node support is designed with a clip-lock structure that is secured upon insertion in one direction and prevents reverse separation, thereby fixing the continuous fiber so that it does not move under tension. Additionally, it can maintain a uniform stress distribution in each direction. This structure maintains the fiber path while providing mechanical stability, and in the case of a 2D lattice base, winding is possible inside or outside a box-shaped mold. This is illustrated in FIG. 2.

[0083] This structure enhances load distribution performance and minimizes fiber damage during the repetition, assembly, and disassembly processes. Furthermore, it is designed to be compatible with various core materials, such as metal rods and foam, offering high applicability; if necessary, it can also be expanded into a sutured structure by curing continuous carbon fibers together as an outer layer. Such a 2D-based 3D expansion structure can be applied to design complex curved surfaces and realize spatial structures with high degrees of freedom.

[0084] According to one embodiment, the unit cell may be optionally removable or retainable.

[0085] In the above structure, by forming a hollow lattice lightweight structure through the selective removal of some supports, load distribution characteristics can be controlled according to the arrangement of unit cells.

[0086] When the structure is configured in a modular form as described above, assembly is possible solely through geometric interlocking, enabling partial replacement, maintenance, and multi-purpose structural design in complex system designs, rather than as a single molded part. Each module can be simply joined by interlocking or hooking rather than by fastening, and the entire structure can be maintained as a self-supporting structure without full adhesion. As a result, the structure proposed in this invention can solve the problems of structural discontinuity, stress concentration, and weight increase associated with conventional fastening lattice structures.

[0087] According to one embodiment, the continuous fiber material may comprise one or more reinforcing fibers selected from the group consisting of carbon fiber, glass fiber, basalt fiber, ceramic fiber, silicon carbide fiber, alumina fiber, aramid fiber, Kevlar fiber, graphite fiber, PBO fiber, PEEK fiber, PPS fiber, and metal fiber; and one or more non-reinforcing fibers selected from the group consisting of polyester, nylon, polyurethane, polyethylene, polypropylene, yarn fiber, cotton fiber, flax fiber, bamboo fiber, silk fiber, and polylactic acid fiber.

[0088] Depending on the selection of these fibers, mechanical strength, electrical conductivity, heat resistance, and flexibility vary, and in particular, it was confirmed that the mechanical strength of the lattice structure based on reinforcing fibers was improved compared to the existing 2D CFRP.

[0089] According to one embodiment, the resin material comprises one or more selected from the group consisting of irreversible thermosetting resins such as epoxy, vinyl ester, unsaturated polyester, phenolic resin, melamine, and urea resin; and the group consisting of reversible thermosetting resins such as Diels-Alder-based resin, Imine-based resins, urea / urethane dynamic resins, and vitrimers, and may comprise a low viscosity resin with a viscosity of 300 to 500 cps.

[0090] The above resin material can easily access the interior or surface of the lattice structure during impregnation, thereby reducing impregnation defects and pore formation, and can form a structure that combines the high-strength mechanical performance of carbon fibers with resin bonding strength.

[0091] According to one embodiment, the lattice high-strength bonding structure may have a three-dimensional structure.

[0092] The 3D node-based winding structure can accommodate various lattice topology configurations, such as triangular and 2D lattice, in addition to crystallographic structures like SC, FCC, and BCC, by using a Type 1 node support that is a multifaceted joint type and a Type 2 node support that is a clip-lock type, or a combination of Type 1 and Type 2 node supports, and can be expanded through assembly to the required size, orientation, and thickness. This is illustrated in FIG. 3.

[0093] Unlike conventional laminate methods, the present invention enables the production of a completely continuous, ultra-high-strength, ultra-lightweight structure, allowing for easy expansion and application to complex three-dimensional structures or large structures. Furthermore, it simultaneously satisfies shape optimization, design modifications for specific applications, and ease of on-site assembly and maintenance, enabling flexible application in various industrial fields.

[0094]

[0095] According to another embodiment of the present invention, a method for manufacturing a lattice high-strength bonding structure may comprise the steps of: preparing a core support including a core branch portion and a node support including a node branch portion; forming a unit cell lattice structure by connecting the node branch portion of the node support to the core branch portion of the core support; arranging a continuous fiber material along the outer surface of the core support and the node support; and impregnating the unit cell, on which the continuous fiber material is wound, with a resin material to form a coating on the surface of the unit cell.

[0096] The final structure obtained through the above steps can be maintained as is within the lattice high-strength bonded structure, and if necessary, part or all of it can be removed from the structure through heat treatment and melting, etc., according to the user's intent. An example in which a part of such a support is removed is shown in FIG. 4. After the resin impregnation step, the structure can be strengthened and the individual components forming the structure can be integrated by curing the resin through heat or UV curing. This is shown in FIG. 5.

[0097] According to one embodiment, the step of winding the continuous fiber material may include: designing one or more single paths capable of covering the outer surface of a support under conditions that the continuous fiber material is not broken in the unit cell; and winding the continuous fiber material along the one or more designed single paths.

[0098] All fibers within the structure consist of a single continuous fiber strand and can be arranged within the structural space formed by unit cells along a continuous path without interruption.

[0099] According to these embodiments, the expensive precision metal molds required in conventional CFRP manufacturing are not required, and the autoclave or hot press process under high temperature and high pressure is not required, so fiber paths can be accurately aligned and fixed without a separate mold.

[0100] In addition, the continuous fiber materials provided around the above supports can be applied to small-batch production and repetitive prototyping by securing a single path through CAD-based path design to ensure precision and repeatability, and can reduce manufacturing costs and time compared to conventional methods. Furthermore, while based on 24k, it can be adjusted to 3k to 72k if necessary to ensure three-dimensional spatial continuity.

[0101] These single continuous fiber paths can distribute mechanical stress transfer and ensure the integrity and strength of the entire structure.

[0102] According to one embodiment, the method may further include a step of winding the continuous fiber material; and subsequently, a step of tensioning the continuous fiber material.

[0103] Continuous carbon fibers can maintain a path within the structure through a tensioning step, have constant tension, and be aligned at an accurate position in space.

[0104] In addition, the above supports are divided into core supports and node supports to accurately fix the position of the fibers, thereby preventing deformation during winding or tensioning.

[0105] According to one embodiment, the resin material may further include the step of drying for 2 to 24 hours after impregnating the unit cell.

[0106] In addition, the drying process described above can be adjusted according to the selected resin material. In one embodiment, room temperature drying may be additionally performed after high-temperature drying.

[0107] According to one embodiment, the method may further include a step of forming a coating on the surface of the unit cell; and subsequently, a porous lightweighting step of selectively removing the unit cell.

[0108] This approach enables design strategies that maximize structural strength by lowering relative density and improving mechanical performance when unit cells are removed.

[0109] When standard thermoplastic filament is used as a material for manufacturing supports, some of the supports can be removed manually using nippers, cutting tools, etc. after curing.

[0110] As another example, parts of the support structure can also be removed through methods such as thermal deformation or mechanical cutting. This method is applicable to high-precision structures that are difficult to remove manually and can be extended to an automated, high-speed post-processing process without the burden of lengthy manual removal.

[0111] As a separate embodiment different from the above-described embodiment, only the outer surface may be composed of CFRP, and the entire internal structure may be printed as a 3D printing-based support structure (3DP support), and a 3D structure winding may be performed on it using a continuous fiber material. Furthermore, the embodiments proposed in the present invention can be extended to such manufacturing methods, and this also falls within the scope of the inventor's design.

[0112]

[0113] In the embodiments of the present invention, an integrated composite material and a method for manufacturing the same are proposed, which overcome the weaknesses of existing technologies throughout the structural design, material composition, and manufacturing process, and simultaneously satisfy high strength, high degree of shape freedom, ultra-lightweight properties, and modularity while also securing buckling resistance. In particular, if the technology proposed in the embodiments of the present invention is linked with future automated devices and optimized design incorporating AI, it can be developed into a general-purpose, high-performance, lightweight structural platform applicable to various industries.

[0114]

[0115] The present invention will be described in detail below through examples. However, these examples represent some experimental methods and configurations to illustrate the invention, and the scope of the invention is not limited to these examples.

[0116]

[0117] <Example 1: Design and Fabrication of Support>

[0118] The support used in the first embodiment of the present invention is divided into two parts. First, the first support is a core support for forming an isotropic BCC (Body-Centered Cubic) structure, which serves as the main lattice element responsible for the stiffness and stability of the entire structure. The second support, the node support, can serve as a connection point that connects the aforementioned multiple core supports to expand the unit cell into a lattice structure. This node support includes multiple node branches extending from the center to form a structure perpendicular to one another, and continuous fiber material can be fixed and wound around these node branches. Not only the node support but also the core support may include core branches perpendicular to one another. The branches included in each of these supports may extend in a structure perpendicular to one another in the axial direction (according to one example, the x-axis, y-axis, and z-axis).

[0119] In this embodiment, carbon fiber was used as the continuous fiber material. The core support and node support were prepared using a Bambu X1 Carbon 3D printer with a density of 1.05 g / cm³. 3 It was printed using gray PLA filament, and lightweighting and structural rigidity were simultaneously secured through a 15% infill setting. At this time, the 3D printer was manufactured with a print resolution of 0.2 mm, a nozzle temperature of 215°C, and a bed temperature of 60°C, as shown in Fig. 6.

[0120]

[0121] <Example 2: Manufacturing Process of Lattice High-Strength Bonded Structure>

[0122] In the second embodiment, a bonded structure was formed by winding carbon fibers, which are high-strength continuous fibers, around a core support and a node support that were manufactured via 3D printing in the same manner as described above and then joined together, except that they were designed with an FCC structure. The carbon fibers used at this time were 24K carbon fiber roving, which are high-strength continuous fibers and were used as the main material for transmitting stress throughout the structure.

[0123] At this time, the carbon fibers were wound along the path of an FCC structure designed through prior programming, as shown in Fig. 7. The high-strength continuous fiber material was precisely fixed to the node branches of each node support and maintained constant tension while extending along the surfaces of the node support and core support. The structure, once wound, was completely immersed in a commercial low-viscosity epoxy resin of approximately 300 to 500 chin and impregnated using a resin bath immersion method to ensure the resin evenly coated the inner surface of the complex lattice. After completely immersing the structure in the resin, internal air bubbles and excess resin were removed through several rotation processes. After impregnation, the structure was naturally cured at room temperature for 24 hours, completing the resin curing without separate high-temperature treatment. Once cured, the PLA support could be removed from the structure through mechanical cutting or heat and melting treatment, and the relative density and mechanical properties of the final structure were adjusted depending on whether the support was removed. The manufacturing process is shown in Fig. 8.

[0124]

[0125] <Example 3: Strength Analysis of Lattice High-Strength Bonded Structure>

[0126] In the third embodiment, the bonding structures of the present invention manufactured in the manner described above were classified according to the manufacturing method into 3D printing, mechanical forming, heat pressing, snap-fit ​​method, and 2D winding method, and the ratio of strength to relative density was analyzed. As a result, under the same relative density conditions, the strength of the lattice high-strength bonding structure manufactured by the manufacturing method proposed in the embodiment of the present invention was 1222.1 MPa, while the conventional method showed a maximum of 227.4 MPa. It was confirmed that when bonding structures are manufactured by the manufacturing method proposed in the embodiment of the present invention, an improvement of up to approximately 5 times or more is possible compared to conventional methods, and the results are shown in the graph of Fig. 9.

[0127]

[0128] <Example 4: Lightweight Analysis of Lattice High-Strength Bonded Structure>

[0129] According to the methods described in the above embodiments, the structure was actually fabricated and designed so that each structure had a size of 50x50x50 mm based on a 2x2x2 three-dimensional FCC unit cell. Then, by modularizing it to form a final lattice high-strength bonded structure, the overall shape of the structure was formed to have a hollow multi-cube form of 100x100x100 mm. At this time, the weight of the entire structure was measured to be approximately 79 g with the 3D printed support included. Subsequently, after removing the intended core support and node support according to the prior design, the weight of the structure was reduced to approximately 34 g.

[0130] This is a total volume of 1,000 cm³ 3 Approximately 0.034 g / cm³ for (100x100x100 mm) 3 It has an average density of approximately 1.6 g / cm³, which is the standard density of carbon fiber composites. 3 An ultra-lightweight structure with a relative density of approximately 0.021 (2.1%) was realized. Figure 10 shows the state before and after the removal of the support.

[0131]

[0132] <Example 5: Comparative Analysis of Compressive Loads of Lattice High-Strength Bonded Structures>

[0133] Based on structures actually fabricated according to the methods described in the aforementioned embodiments, deformation behavior and compressive strength were calculated and compared according to the configuration of each structure. Structures consisting solely of a core support of the BCC structure, high-strength lattice bonding structures of SCC and FCC including a support, and high-strength lattice bonding structures of SCC and FCC without a support were fabricated in sizes of 25mm, 37mm, and 50mm for comparison. Under identical structural conditions, smaller sizes exhibited higher compressive load values, and among the high-strength lattice bonding structures of SCC and FCC including a support, the FCC structure exhibited a higher compressive load value. In the same structure, removing the support resulted in a lower compressive load value than including the support, indicating that smaller sizes represent higher strength. Since no change was observed in the result pattern depending on whether the support was removed or not, no significant change in structural contribution was confirmed. Conversely, the high-strength lattice bonding structure including a support exhibited a relatively stronger compressive load value than the one without a support. Consequently, the strength difference in terms of structure was confirmed as BCC < SCC < FCC. The results are shown in Figure 11.

[0134]

[0135] <Example 6: Finite Element Analysis of a Lattice High-Strength Bonded Structure>

[0136] High-strength lattice bonding structures in beam and multi-cube forms were designed by stacking and expanding unit cells according to the methods described in the above-mentioned embodiments. At this time, the high-strength lattice bonding structures were designed using continuous fibers that extend without interruption by winding along the path of an FCC structure designed in advance through programming, as shown in Fig. 12. As a result of analyzing the stress distribution of FEA simulations using ANSYS Static Structural, it was confirmed that more stable strength and stability were secured in the multi-unit cell structure compared to the single-unit cell structure. In the beam structure, it was confirmed that buckling occurred after the longest displacement and peak, while in the multi-cube structure, small displacement and a sharp buckling peak were observed, confirming minimal deformation. The results are shown in Fig. 13.

[0137]

[0138] <Example 7: Comparison of Mechanical Properties of Lattice High-Strength Bonded Structures>

[0139] The mechanical properties of the lattice structure produced in the embodiment of the present invention were compared using a strength-density graph, and the results are shown in FIG. 14. As a result, the structure of the present invention showed a strength improvement of about 5 times or more compared to conventional foam, and it was confirmed that a compressive strength of up to 200 MPa was secured at the same density.

[0140] In particular, the structure incorporating an FCC structure and Type B clip-lock nodes demonstrated performance approaching that of conventional CFRP composites in terms of strength-to-density ratio, proving that it is an ultra-lightweight, ultra-high-strength composite structure approaching the theoretical limit.

[0141]

[0142] <Example 8: Comparison of Electrical Properties of Lattice High-Strength Bonded Structures>

[0143] To verify the electrical properties of the three-dimensional node-based continuous fiber composite structure of the present invention, the voltage-time behavior of a Nylon-based insulating structure and a CFRL structure (CFRL1, CFRL2) according to the present invention was compared, and the results are shown in FIG. 15.

[0144] As a result of the experiment, the voltage of the Nylon specimen dropped rapidly to below 10V within about 11 minutes, whereas the CFRL1 specimen maintained a stable voltage for about 14.5 minutes and the CFRL2 specimen for about 16 minutes. In particular, the CFRL2 specimen, which features a Type B clip-lock node structure, reduced contact resistance between continuous fibers, thereby improving the stability of the conduction path and improving the voltage holding time by more than 40%.

[0145] This suggests that the structure of the present invention can be expanded beyond a simple mechanical structure into a multifunctional composite platform equipped with electrical functionality.

[0146]

[0147] <Example 9: Application Demonstration of Lattice High-Strength Bonding Structure>

[0148] A robot arm, a drone, and a small airplane were implemented using the manufacturing method of the present invention, and their weight reduction, strength, and efficiency were verified, as shown in FIG. 16. A robot arm was implemented by actually replacing two links and applying an SC / FCC lattice structure. As a result of verifying weight reduction, strength, and efficiency by applying an SC / FCC lattice with a single continuous fiber path, the mass was reduced by approximately 53.7%, and the joint torque and current were reduced by 23 to 45%. Although the maximum load increased by approximately 9.7%, it was confirmed that the structural efficiency (N / kg) improved by approximately 137%. In addition, it was confirmed that there was no damage to the joints even under repeated operation.

[0149] Next, a drone frame was implemented using an X-shaped lattice beam with an FCC / SC mixed design structure. It was confirmed that the frame mass was 40% to 79% lighter compared to standard nylon. System power was reduced by 18% to 25%, and flight time increased by 22% to 33%. By applying FCC-based beams and SC reinforcement beams in alternation, lightweighting and durability could be secured simultaneously, and the ability to replace and rearrange modules allows for expansion into various drone configurations.

[0150] In addition, a small aircraft was realized using a multi-lattice mixed structure in a modular format. The wings were implemented using a triangular prism lattice, and the design incorporated a 2D square grid tail, an SC fuselage, and FCC node reinforcement. Node joint strength could be secured through a continuous fiber path, and the relative density and strength-to-weight ratio could be adjusted by selectively removing the support structure. This suggests that the design is not limited to existing SC / FCC / BCC topologies but can be expanded to various topologies such as triangular prisms and 2D grids.

[0151] Accordingly, it was confirmed that there is platform potential applicable not only to simple small aircraft but also to complex entire aircraft structures (integrated fuselage-wing-tail type).

[0152]

[0153] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

1. Multiple core supports; A node support connected to the ends of the above-mentioned core supports to form a connection between a plurality of core supports; A continuous fiber material provided to be continuously connected without interruption along the outer surface of a three-dimensional structure composed of the core support and the node support; and A resin material comprising a covering formed on the core support, node support, and continuous fiber material; Lattice high-strength bonding structure.

2. In Paragraph 1, One or more of the core support and node support are selected from the group consisting of PLA, ABS, PETG, TPU, Nylon, PC, and ASA, which are 3D printing-based thermoplastic resin-based filaments; and Comprising one or more selected from the group consisting of water-soluble support filaments, PVA and BVOH, Lattice high-strength bonding structure.

3. In Paragraph 1, The above-mentioned core support comprises a plurality of core branches extending in a rod shape from the center to form a vertical structure relative to each other. Lattice high-strength bonding structure.

4. In Paragraph 1, The above-mentioned node support comprises a first type of node support including a plurality of node branches extending from the center to form a vertical structure among themselves; and A second type node support having a clip-lock structure that is difficult to separate in the reverse direction after insertion by pressing in one direction; Lattice high-strength bonding structure.

5. In Paragraph 4, The node branch portion of the first type node support has a smaller diameter compared to the core branch portion, the end of the node branch portion is inserted into the end of the core branch portion, and the core supports are connected to form a single unit cell. Lattice high-strength bonding structure.

6. In Paragraph 5, In the above-mentioned unit cell, the center of the core support becomes the body center of the BCC (Body-Centered Cubic) structure, and the center of the first type node support forms the outer edge of the BCC structure to form a unit cell unit. Lattice high-strength bonding structure.

7. In Paragraph 5, The above unit cell crystallographically has a lattice form among SC, BCC, and FCC structures, Lattice high-strength bonding structure.

8. In Paragraph 4, The above-mentioned second type node support is connected to the core support to form a single two-dimensional unit cell, and The above two-dimensional unit cell is configured to be continuously expanded into a three-dimensional node structure, Lattice high-strength bonding structure.

9. In Paragraph 5, The above unit cell is optionally removable or retainable. Lattice high-strength bonding structure.

10. In Paragraph 1, The above continuous fiber material is one or more selected from the group consisting of reinforcing fibers such as carbon fiber, glass fiber, basalt fiber, ceramic fiber, silicon carbide fiber, alumina fiber, aramid fiber, Kevlar fiber, graphite fiber, PBO fiber, PEEK fiber, PPS fiber, and metal fiber; and Comprising one or more selected from the group consisting of non-reinforced fibers such as polyester, nylon, polyurethane, polyethylene, polypropylene, yarn fiber, cotton fiber, linen fiber, bamboo fiber, silk fiber, and polylactic acid fiber, Lattice high-strength bonding structure.

11. In Paragraph 1, The above resin material comprises one or more selected from the group consisting of irreversible thermosetting resins such as epoxy, vinyl ester, unsaturated polyester, phenolic resin, melamine, and urea resin; and the group consisting of reversible thermosetting resins such as Diels-Alder-based resin, Imine-based resins, urea / urethane dynamic resins, and vitrimers. A low-viscosity resin having a viscosity of 300 to 500 cps, Lattice high-strength bonding structure.

12. In Paragraph 1, The above-mentioned lattice high-strength bonding structure is having a three-dimensional structure, Lattice high-strength bonding structure.

13. A step of preparing a core support including a core branch portion and a node support including a node branch portion; A step of forming a unit cell lattice structure by connecting the node branch portion of a node support to the core branch portion of the core support; A step of arranging a continuous fiber material along the outer surface of the core support and the node support; and The method comprising the step of impregnating the unit cell, on which the above-mentioned continuous fiber material is wound, with a resin material to form a coating on the surface of the unit cell; Method for manufacturing a lattice high-strength bonded structure.

14. In Paragraph 13, The step of winding the above continuous fiber material is, A step of designing one or more single paths capable of covering the outer surface of a support under the condition that the continuous fiber material is not broken in the above unit cell; and A step of winding a continuous fiber material along one or more single paths designed above; comprising Method for manufacturing a lattice high-strength bonded structure.

15. In Paragraph 14, The step of winding the above continuous fiber material; thereafter, The method further comprises the step of tensioning the above continuous fiber material. Method for manufacturing a lattice high-strength bonded structure.

16. In Paragraph 13, The above resin material further comprises the step of drying for 2 to 24 hours after impregnating the unit cells. Method for manufacturing a lattice high-strength bonded structure.

17. In Paragraph 13, A step of forming a coating on the surface of the unit cell; thereafter, A porous lightweighting step that selectively removes unit cells; further comprising Method for manufacturing a lattice high-strength bonded structure.

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