A dual unit three-dimensional woven spacer fabric, composites thereof, and methods of making

Abstract

A kind of double unit three-dimensional woven spacer fabric, and its composite material and preparation method, warp yarn includes upper layer warp yarn and lower layer warp yarn;Weft yarn includes upper layer weft yarn, lower layer weft yarn, in-layer weft yarn between upper layer weft yarn and lower layer weft yarn and functional weft yarn;Spacer yarn includes spacer yarn I and spacer yarn II;Two groups of upper layer warp yarn and upper layer weft yarn are woven to form upper layer fabric;Two groups of lower layer warp yarn and lower layer weft yarn are woven to form lower layer fabric;Spacer yarn I and spacer yarn II and upper layer weft yarn and lower layer weft yarn are woven to form spacer fabric;In-layer weft yarn and spacer yarn are woven to form rectangular structure unit;Functional weft yarn and spacer yarn are woven to form functional unit.In the present application, functional weft yarn and spacer yarn are woven in plain weave structure, realize the fixation of functional unit in cavity, protected by upper and lower panel;In-layer weft yarn and spacer yarn are woven with plain weave structure, form rectangular structure unit perpendicular to upper and lower panel, realize the separation protection of functional unit group, provide mechanical bearing performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of textile technology and composite materials, and particularly relates to a double-unit three-dimensional woven spacer fabric, a composite material thereof and a preparation method. BACKGROUND

[0002] With the development of science and technology, the pursuit of composite materials is not only limited to higher bearing capacity, and functionality is also an important development direction. Structural and functional integrated composite materials have both structural bearing capacity and functionality, and are an important trend in the development of composite materials. Textile structure composite materials use textile structure products as reinforcement and resins, ceramics, metals, etc. as matrix, and have high stiffness and strength. Because the textile structure has flexible organization design, functional materials can be completely embedded in the textile structure to realize the integration of function and bearing. In recent years, the structural and functional integrated design of traditional laminated plates and three-dimensional orthogonal composite materials has developed rapidly. However, although traditional laminated textile composite materials can integrate functional materials into the panel, they are prone to delamination damage and functional damage under external force, leading to failure. Three-dimensional orthogonal composite materials solve the problem of delamination damage, but they are still prone to damage to functional materials under external force, and the large density limits their application in lightweight scenarios. In addition, functional materials in the textile structure lack separation protection and may interfere with each other, causing malfunctions and accidents, such as signal transmission line interference failure, conductor insulation layer aging short circuit causing fire and explosion, etc.

[0003] Three-dimensional woven spacer fabric reinforced composite materials connect the upper and lower panels with spacer yarns, solving the problem of easy delamination of traditional composite materials, and are a lightweight high-strength anti-delamination composite material with an overall structure, widely used in fields such as aircraft, high-speed rail, oil storage tanks, wind power blades, antenna covers, etc. Its unique hollow structure provides sufficient space for the integration and separation protection of functional materials, but due to the limitation of traditional spacer structure, the functional integration and separation protection application potential of three-dimensional woven spacer composite materials has not been fully developed and utilized, which limits their application in structural and functional integrated design scenarios. SUMMARY

[0004] The technical problem solved by the present application is the integration and separation protection of functional materials in three-dimensional woven spacer fabric and its composite materials, and for this purpose, a double-unit three-dimensional woven spacer fabric with functional integration and separation protection function, a composite material thereof and a preparation method are provided.

[0005] The present application solves the above technical problems through the following technical solutions.

[0006] In a first aspect of the present application, a double-unit three-dimensional woven spacer fabric is provided, comprising warp yarns, weft yarns and spacer yarns, wherein the warp yarns comprise upper-layer warp yarns and lower-layer warp yarns; the weft yarns comprise upper-layer weft yarns, lower-layer weft yarns, intra-layer weft yarns between the upper-layer weft yarns and the lower-layer weft yarns, and functional weft yarns; the spacer yarns comprise spacer yarn I and spacer yarn II; two groups of the upper-layer warp yarns are interwoven with the upper-layer weft yarns to form an upper-layer fabric; two groups of the lower-layer warp yarns are interwoven with the lower-layer weft yarns to form a lower-layer fabric; the spacer yarn I and the spacer yarn II are interwoven with the upper-layer weft yarns and the lower-layer weft yarns to form a spacer fabric; the intra-layer weft yarns are interwoven with the spacer yarns to form a rectangular structure unit; and the functional weft yarns are interwoven with the spacer yarns to form a functional unit.

[0007] In a second aspect of the present application, a double-unit three-dimensional woven spacer fabric reinforced composite material is provided, characterized in that the double-unit three-dimensional woven spacer fabric is formed into the double-unit three-dimensional woven spacer fabric reinforced composite material with a resin solution.

[0008] In a third aspect of the present application, a preparation method of the double-unit three-dimensional woven spacer fabric is provided, comprising the following steps:

[0009] Step 1: process preparation: selecting yarns according to the required performance of the fabric, wherein the fineness of the yarns is 100-1200 tex; determining the weave of the upper-layer fabric and the lower-layer fabric to be one of plain weave, twill weave, satin weave and their variation weaves; the warp density is 30-100 roots / 10 cm; the weft density is 20-150 roots / 10 cm; the spacer yarn density is 15-50 roots / 10 cm; the width is 20-200 cm; the spacer height is 4-30 mm; the weaving tension is controlled within 5-10 N; and preparing corresponding reeds and harnesses;

[0010] Step 2: yarn threading: threading one group of upper-layer warp yarns and lower-layer warp yarns on one piece of double-eye heddle according to a rule; threading another group of upper-layer warp yarns and lower-layer warp yarns on another piece of double-eye heddle according to a rule; controlling the interweaving of the upper-layer fabric and the lower-layer fabric by the two pieces of double-eye heddle; threading two groups of spacer yarns on two pieces of single-eye heddle according to a rule respectively, and controlling the interweaving of the spacer yarns by the two pieces of single-eye heddle; threading the upper-layer weft yarns and the lower-layer weft yarns on the upper and lower sword bars respectively; and threading the intra-layer weft yarns and the functional weft yarns on the middle sword bar I and the middle sword bar II respectively;

[0011] Step 3: spacer fabric structure weaving: introducing the weft yarns between the two groups of upper-layer warp yarns by the upper sword bar, introducing the weft yarns between the two groups of lower-layer warp yarns by the lower sword bar, setting the spacer device height to 4-30 mm to control the spacing of the interwoven upper-layer yarns and lower-layer yarns, i.e. the height of the spacer fabric; beating the weft yarns by the reed; changing the heddles of the two pieces of double-eye heddle and the two pieces of single-eye heddle respectively to form a normal woven spacer fabric structure unit;

[0012] Step 4: Rectangular unit weaving: for the convenience of description, it is assumed that the spacer yarn I is located at the uppermost layer of the shed, and the spacer yarn II is located at the lowermost layer of the shed; the spacer yarn II is lifted to the uppermost layer of the shed and is flush with the spacer yarn I; the upper sword guide introduces the weft yarns between the two groups of spacer yarns; the spacer yarn II is lowered to the lowermost layer of the shed; the middle sword guide I introduces the weft yarns between the two groups of spacer yarns, the reed beats the weft yarns, and the two pieces of single-eye harness frame perform a harness change, so that the weft yarns and the spacer yarns in the same layer are interwoven once; the weft yarns and the spacer yarns in the same layer are interwoven repeatedly in the same way until the length of the plain fabric formed reaches the spacer height; for the convenience of description, it is assumed that the number of repetitions is 2n times, the spacer yarn I is located at the uppermost layer of the shed, and the spacer yarn II is located at the lowermost layer of the shed; the spacer yarn I is lowered to the lowermost layer of the shed and is flush with the spacer yarn II; the lower sword guide introduces the weft yarns to the two groups of spacer yarns; the spacer yarn I is lifted to the uppermost layer of the shed; the reed beats the weft yarns, and the two pieces of double-eye harness frame perform a harness change, so that the upper and lower fabrics are interwoven once; a rectangular unit is formed;

[0013] Step 5: Functional unit weaving: the middle sword guide II introduces the weft yarns between the upper fabric and the lower fabric, the reed beats the weft yarns, and the two pieces of single-eye harness frame perform a harness change, so that the functional weft yarns and the spacer yarns are interwoven once; the functional weft yarns and the spacer yarns are interwoven once again in the same way; then the upper sword guide introduces the weft yarns between the two groups of upper warp yarns, and the lower sword guide introduces the weft yarns between the two groups of lower warp yarns; the reed beats the weft yarns; the two pieces of double-eye harness frame perform a harness change, so that the upper and lower fabrics are interwoven once; the upper and lower fabrics are interwoven once in the same way; the reed beats the weft yarns; the two pieces of single-eye harness frame perform a harness change, so that the spacer fabric is interwoven once; a functional unit is formed;

[0014] Step 6: Double-unit three-dimensional woven spacer fabric weaving: steps 4 and 5 are alternately or variably woven to obtain a double-unit three-dimensional woven spacer fabric;

[0015] In a fourth aspect of the present application, a preparation method of a double-unit three-dimensional woven spacer fabric reinforced composite material is provided, which comprises the following steps:

[0016] Step 1: Process preparation: selecting yarns according to the required performance of the fabric, wherein the fineness of the yarns is 100-1200 tex; determining that the organization of the upper and lower fabrics is one of plain weave, twill weave, satin weave and their variation organizations; the warp density is 30-100 roots / 10 cm; the weft density is 20-150 roots / 10 cm; the spacer yarn density is 15-50 roots / 10 cm; the width is 20-200 cm; the spacer height is 4-30 mm; the weaving tension is controlled within 5-10 N; and corresponding reeds and harness frames are prepared;

[0017] Step 2: Yarn threading: Thread one set of upper and lower warp yarns onto a double-heddle frame according to a pattern; thread another set of upper and lower warp yarns onto another double-heddle frame according to a pattern; the two double-heddle frames control the interweaving of the upper and lower fabrics; thread two sets of spacer yarns onto two single-heddle frames according to a pattern; the two single-heddle frames control the interweaving of the spacer yarns; thread the upper and lower weft yarns onto the upper and lower rapiers respectively; thread the inner-layer weft yarns and functional weft yarns onto the middle rapier I and middle rapier II respectively;

[0018] Step 3: Weaving of the spacer fabric structure: The upper rapier guides the weft yarn between two sets of upper warp yarns, and the lower rapier guides the weft yarn between two sets of lower warp yarns. The height of the spacer device is set to 4-30mm to control the spacing after the upper and lower yarns interweave, which is the height of the spacer fabric; the reed beats the weft; the two double-heald frames and the two single-heald frames are replaced with heddles respectively to form a normal machine-woven spacer fabric structure unit;

[0019] Step 4: Rectangular Unit Weaving: For ease of description, assume that spacer yarn I is at the top layer of the weft and spacer yarn II is at the bottom layer. Lift spacer yarn II to the top layer of the weft, making it flush with spacer yarn I. The upper rapier guides the weft yarn under the two sets of spacer yarns. Lower spacer yarn II to the bottom layer of the weft. The middle rapier I guides the weft yarn between the two sets of spacer yarns. The reed beats the weft, and the two single-heald frames perform one heald change, achieving one layer of interlacing of the weft and spacer yarns. Repeat the same method for the layer of weft yarns. The interlacing of the yarn and spacer yarn continues until the length of the plain weave fabric reaches the spacer height. For ease of description, it is assumed that the number of repetitions is 2n times. Spacer yarn I is located at the top layer of the weave opening, and spacer yarn II is located at the bottom layer of the weave opening. Spacer yarn I is lowered to the bottom layer of the weave opening, level with spacer yarn II. The lower rapier guides the weft yarn onto the two sets of spacer yarns. Spacer yarn I is lifted to the top layer of the weave opening. The reed beats the weft, and the two double-heddle frames perform one heddle change, and the upper and lower layers of fabric are interlaced once, forming a rectangular unit.

[0020] Step 5: Functional Unit Weaving: The middle rapier II introduces the weft yarn between the upper and lower layers of fabric. The reed beats the weft, and the two single-heddle frames perform a heddle change, achieving one interweaving of the functional weft yarn and the spacer yarn. The same method is used to perform another interweaving of the functional weft yarn and the spacer yarn. Then, the upper rapier introduces the weft yarn between the two sets of upper warp yarns, and the lower rapier introduces the weft yarn between the two sets of lower warp yarns. The reed beats the weft; the two double-heddle frames perform a heddle change, achieving one interweaving of the upper and lower layers of fabric. The same method is used to complete another interweaving of the upper and lower layers of fabric. The reed beats the weft; the two single-heddle frames perform a heddle change, achieving one interweaving of the spacer fabric. This forms a functional unit.

[0021] Step 6: Weaving of the two-unit three-dimensional woven spacer fabric: Steps 4 and 5 are performed alternately or in different ways to weave the two-unit three-dimensional woven spacer fabric.

[0022] Step 7: Resin preparation: Mix the resin and curing agent according to the ratio and stir for 5-15 minutes to ensure that they are evenly mixed;

[0023] Step 8: Resin Impregnation: Place the fabric on a mold coated with release agent; use a dropper to evenly apply the resin solution in an "S" shape along the weft direction once, then evenly apply it in an "S" shape along the warp direction once. Let it stand for 30-300 seconds to allow it to penetrate and impregnate. Turn the fabric over and use a dropper to evenly apply the resin solution in an "S" shape along the weft direction once, then evenly apply it in an "S" shape along the warp direction once. Let it stand for 30-300 seconds to allow it to penetrate and impregnate. Repeat the above operation until the resin solution content is 30%-80% of the total mass and the fabric content is 20%-70% of the total mass.

[0024] Step 9: Composite molding: Place the resin-impregnated fabric into an oven and pre-cur and cure it at 50-320℃ for 3-12 hours to obtain a two-unit three-dimensional woven spacer fabric reinforced composite material.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The dual-unit three-dimensional woven spacer fabric obtained by the present invention introduces in-layer weft yarns and functional weft yarns. By changing the movement law of the heald frame, the combined weaving of rectangular units and functional units is realized, the structure of the three-dimensional woven spacer fabric is optimized, the mechanical properties of its composite material are effectively improved, and the functional units are separated and protected.

[0027] 2. In this invention, the functional weft yarn and the spacer yarn are interwoven in a plain weave structure, which realizes the fixation of the functional unit in the cavity and is protected by the upper and lower panels.

[0028] 3. In this invention, the inner weft yarn and the spacer yarn are interwoven in a plain weave structure to form a rectangular structural unit, which provides excellent mechanical load-bearing performance for the three-dimensional woven spacer composite material; the rectangular unit divides the continuous cavity and separates multiple independent functional unit groups to prevent them from interfering with each other and realize the separation and protection function.

[0029] 4. In this invention, the height position of the functional unit can be adjusted arbitrarily; by introducing different functional weft yarns, the functional unit can be designed with multiple functions, resulting in diversified functional products that can meet the usage needs of different scenarios.

[0030] 5. This invention provides a weaving method for a two-unit three-dimensional woven spacer fabric. The method, principle, and process are simple and easy to operate, and can achieve large-scale, industrialized production.

[0031] 6. The dual-unit three-dimensional woven spacer fabric and its composite material obtained by this invention have broad application prospects in the fields of aircraft, high-speed rail, oil storage tanks, wind turbine blades, and radomes. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of one of the weave structures of the dual-unit three-dimensional woven spacer fabric described in this invention.

[0033] Figure 2 This is a top view schematic diagram of one of the weave structures of the dual-unit three-dimensional woven spacer fabric described in this invention.

[0034] Figure 3 This is a schematic diagram of the warp cross-section of one of the weave structures of the dual-unit three-dimensional woven spacer fabric described in this invention.

[0035] Figure 4 This is a schematic diagram of the weft section of one of the weave structures of the dual-unit three-dimensional woven spacer fabric described in this invention.

[0036] Figure labels: 1. Upper warp yarn; 2. Lower warp yarn; 3. Upper weft yarn; 4. Lower weft yarn; 5. Spacer yarn; 6. Functional weft yarn; 7. Spacer yarn I; 8. Spacer yarn II. Detailed Implementation

[0037] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings:

[0038] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, a dual-unit three-dimensional woven spacer fabric includes warp yarns, weft yarns, and spacer yarns 5. The warp yarns include upper warp yarns 1 and lower warp yarns 2; the weft yarns include upper weft yarns 3, lower weft yarns 4, inner-layer weft yarns located between the upper and lower weft yarns, and functional weft yarns 6; the spacer yarns 5 include spacer yarn I 7 and spacer yarn II 8; the two sets of upper warp yarns interweave with the upper weft yarns to form an upper fabric; the two sets of lower warp yarns interweave with the lower weft yarns to form a lower fabric; the spacer yarns I and II interweave with the upper and lower weft yarns to form a spacer fabric; the inner-layer weft yarns interweave with the spacer yarns to form a rectangular structural unit; and the functional weft yarns interweave with the spacer yarns to form a functional unit.

[0039] The warp yarn, upper weft yarn, lower weft yarn, inner weft yarn, and spacer yarn of the present invention are selected from one or more of chemical fibers, natural fibers, and inorganic fibers.

[0040] The natural fibers of this invention are selected from one or more of ramie, jute, and flax.

[0041] The inorganic fibers of this invention are selected from one or more of glass fibers, carbon fibers, quartz fibers, basalt fibers, and ceramic fibers.

[0042] The chemical fibers of this invention are selected from one or more of aramid fibers, ultra-high molecular weight polyethylene fibers, polypropylene fibers, polyethylene fibers, polyester fibers, and acrylic fibers.

[0043] The functional weft yarn of this invention is selected from one or more of conductive yarn, electric heating yarn, sensing yarn, and thermally conductive yarn.

[0044] The conductive yarn of the present invention is selected from one or more of copper wire fiber, stainless steel fiber, carbon nanotube yarn and silver-plated yarn.

[0045] The electrothermal yarn of the present invention is selected from one or more of carbon fiber, graphene fiber, Mxene coated yarn and carbon nanotube coated yarn.

[0046] The sensing yarn of this invention is selected from one or more of carbon nanotube yarn, carbon nanotube membrane roll yarn, and graphene yarn.

[0047] The thermally conductive yarn of the present invention is selected from one or more of carbon nanotube yarn, stainless steel fiber and microfluidic tube.

[0048] A dual-unit three-dimensional woven spacer fabric reinforced composite material is disclosed, wherein the dual-unit three-dimensional woven spacer fabric is reacted with a resin solution to form the dual-unit three-dimensional woven spacer fabric reinforced composite material. The resin solution is selected from one or more of epoxy resin, vinyl resin, polyimide resin, and phenolic resin.

[0049] A method for preparing a two-unit three-dimensional woven spacer fabric includes the following steps:

[0050] Step 1: Process Preparation: Select the yarns according to the required properties of the fabric, wherein the fineness of the yarns is 100-1200 tex; determine the weave structure of the upper and lower layers of fabric as plain weave, twill weave, satin weave, or a variation thereof; warp density is 30-100 ends / 10cm; weft density is 20-150 ends / 10cm; spacer yarn density is 15-50 ends / 10cm; width is 20-200cm; spacing height is 4-30mm; weaving tension is controlled at 5-10N; prepare the corresponding reeds and heald frames.

[0051] Step 2: Yarn threading: Thread one set of upper and lower warp yarns onto a double-heddle frame according to a pattern; thread another set of upper and lower warp yarns onto another double-heddle frame according to a pattern; the two double-heddle frames control the interweaving of the upper and lower fabrics; thread two sets of spacer yarns onto two single-heddle frames according to a pattern; the two single-heddle frames control the interweaving of the spacer yarns; thread the upper and lower weft yarns onto the upper and lower rapiers respectively; thread the inner-layer weft yarns and functional weft yarns onto the middle rapier I and middle rapier II respectively;

[0052] Step 3: Weaving of the spacer fabric structure: The upper rapier guides the weft yarn between two sets of upper warp yarns, and the lower rapier guides the weft yarn between two sets of lower warp yarns. The height of the spacer device is set to 4-30mm to control the spacing after the upper and lower yarns interweave, which is the height of the spacer fabric; the reed beats the weft; the two double-heald frames and the two single-heald frames are replaced with heddles respectively to form a normal machine-woven spacer fabric structure unit;

[0053] Step 4: Rectangular Unit Weaving: For ease of description, assume that spacer yarn I is at the top layer of the weft and spacer yarn II is at the bottom layer. Lift spacer yarn II to the top layer of the weft, making it flush with spacer yarn I. The upper rapier guides the weft yarn under the two sets of spacer yarns. Lower spacer yarn II to the bottom layer of the weft. The middle rapier I guides the weft yarn between the two sets of spacer yarns. The reed beats the weft, and the two single-heald frames perform one heald change, achieving one layer of interlacing of the weft and spacer yarns. Repeat the same method for the layer of weft yarns. The interlacing of the yarn and spacer yarn continues until the length of the plain weave fabric reaches the spacer height. For ease of description, it is assumed that the number of repetitions is 2n times. Spacer yarn I is located at the top layer of the weave opening, and spacer yarn II is located at the bottom layer of the weave opening. Spacer yarn I is lowered to the bottom layer of the weave opening, level with spacer yarn II. The lower rapier guides the weft yarn onto the two sets of spacer yarns. Spacer yarn I is lifted to the top layer of the weave opening. The reed beats the weft, and the two double-heddle frames perform one heddle change, and the upper and lower layers of fabric are interlaced once, forming a rectangular unit.

[0054] Step 5: Functional Unit Weaving: The middle rapier II introduces the weft yarn between the upper and lower layers of fabric. The reed beats the weft, and the two single-heddle frames perform a heddle change, achieving one interweaving of the functional weft yarn and the spacer yarn. The same method is used to perform another interweaving of the functional weft yarn and the spacer yarn. Then, the upper rapier introduces the weft yarn between the two sets of upper warp yarns, and the lower rapier introduces the weft yarn between the two sets of lower warp yarns. The reed beats the weft; the two double-heddle frames perform a heddle change, achieving one interweaving of the upper and lower layers of fabric. The same method is used to complete another interweaving of the upper and lower layers of fabric. The reed beats the weft; the two single-heddle frames perform a heddle change, achieving one interweaving of the spacer fabric. This forms a functional unit.

[0055] Step 6: Weaving of the two-unit three-dimensional woven spacer fabric: Steps 4 and 5 are performed alternately or in different ways to weave the two-unit three-dimensional woven spacer fabric.

[0056] The method for preparing a two-unit three-dimensional woven spacer fabric according to the present invention shall satisfy one or more of the following conditions:

[0057] Condition 1 is that in step 1, the yarn is one or more of chemical fibers, inorganic fibers, natural fibers, and functional yarns;

[0058] Condition 2 is that the fabric structure, warp and weft density, spacing yarn density, width, length, spacing height, and weaving tension in step 1 are designed according to actual requirements;

[0059] Condition 3 is that in step 2, the warp threading pattern is that the nth warp of each upper layer of warp is threaded through the upper heddle eye of the nth heddle wire in its corresponding heddle frame, and the nth warp of each lower layer of warp is threaded through the lower heddle eye of the nth heddle wire in its corresponding heddle frame, wherein the rightmost warp is the first warp.

[0060] Condition 4 is that in step 2, the threading pattern of the spacer yarns is such that the nth yarn of each group of spacer yarns is threaded through the nth heddle wire of its corresponding heddle frame; the nth yarn of spacer yarn I passes between the (2n-1)th and (2n-2)th heddle wires of the double heddle frame; the nth yarn of spacer yarn II passes between the 2nth and (2n-1)th heddle wires of the double heddle frame; where the rightmost spacer yarn is considered the first yarn;

[0061] Condition 5 is that in step 4, the rectangular unit is perpendicular to the upper and lower fabric layers.

[0062] Condition 6 is that in step 5, the number of interlacing times between the functional weft yarn and the spacer yarn is 2n;

[0063] Condition 7 is that in step 5, the functional weft yarn and the spacer yarn interlacing unit are parallel to the upper and lower fabric layers.

[0064] Condition 8 is that in step 5, the height of the interlacing unit of the functional weft yarn and the spacer yarn can be controlled by the tension of the upper and lower sets of spacer yarns; or it can be controlled by adding an external spacer device.

[0065] Condition 9 is that in step 5, the position of the interlacing unit of the functional weft yarn and the spacer yarn is at the halfway point between the upper and lower fabrics;

[0066] Condition 10 is that in step 5, the functional weft yarn and the spacer yarn interweave twice to form the minimum cycle; the upper and lower layers of fabric interweave once to form the minimum cycle.

[0067] Condition 11 states that in step 5, different functional unit groups with different combinations of cycle counts can be designed according to actual needs.

[0068] Condition 12 is that in step 6, the alternation pattern of rectangular units and functional units can be designed according to actual needs to form a two-unit three-dimensional woven spacer fabric with different cycle patterns.

[0069] More preferably, the upper weft yarn, lower weft yarn, inner weft yarn, and spacer yarn are selected from one or more of glass fiber, aramid, carbon fiber, ultra-high molecular weight polyethylene fiber, ramie, jute, flax, polypropylene fiber, polyethylene fiber, polyester, and acrylic fiber; the functional weft yarn is selected from one or more of copper wire fiber, stainless steel fiber, silver-plated yarn, carbon nanotube yarn, carbon nanotube coated yarn, carbon fiber, graphene fiber, Mxene coated yarn, carbon nanotube membrane roll yarn, and microfluidic tube.

[0070] The present invention discloses a method for preparing a two-unit three-dimensional woven spacer fabric composite material, comprising the following steps:

[0071] Step 1: Process Preparation: Select the yarns according to the required properties of the fabric, wherein the fineness of the yarns is 100-1200 tex; determine the weave structure of the upper and lower layers of fabric as plain weave, twill weave, satin weave, or a variation thereof; warp density is 30-100 ends / 10cm; weft density is 20-150 ends / 10cm; spacer yarn density is 15-50 ends / 10cm; width is 20-200cm; spacing height is 4-30mm; weaving tension is controlled at 5-10N; prepare the corresponding reeds and heald frames.

[0072] Step 2: Yarn threading: Thread one set of upper and lower warp yarns onto a double-heddle frame according to a pattern; thread another set of upper and lower warp yarns onto another double-heddle frame according to a pattern; the two double-heddle frames control the interweaving of the upper and lower fabrics; thread two sets of spacer yarns onto two single-heddle frames according to a pattern; the two single-heddle frames control the interweaving of the spacer yarns; thread the upper and lower weft yarns onto the upper and lower rapiers respectively; thread the inner-layer weft yarns and functional weft yarns onto the middle rapier I and middle rapier II respectively;

[0073] Step 3: Weaving of the spacer fabric structure: The upper rapier guides the weft yarn between two sets of upper warp yarns, and the lower rapier guides the weft yarn between two sets of lower warp yarns. The height of the spacer device is set to 4-30mm to control the spacing after the upper and lower yarns interweave, which is the height of the spacer fabric; the reed beats the weft; the two double-heald frames and the two single-heald frames are replaced with heddles respectively to form a normal machine-woven spacer fabric structure unit;

[0074] Step 4: Rectangular Unit Weaving: For ease of description, assume that spacer yarn I is at the top layer of the weft and spacer yarn II is at the bottom layer. Lift spacer yarn II to the top layer of the weft, making it flush with spacer yarn I. The upper rapier guides the weft yarn under the two sets of spacer yarns. Lower spacer yarn II to the bottom layer of the weft. The middle rapier I guides the weft yarn between the two sets of spacer yarns. The reed beats the weft, and the two single-heald frames perform one heald change, achieving one layer of interlacing of the weft and spacer yarns. Repeat the same method for the layer of weft yarns. The interlacing of the yarn and spacer yarn continues until the length of the plain weave fabric reaches the spacer height. For ease of description, it is assumed that the number of repetitions is 2n times. Spacer yarn I is located at the top layer of the weave opening, and spacer yarn II is located at the bottom layer of the weave opening. Spacer yarn I is lowered to the bottom layer of the weave opening, level with spacer yarn II. The lower rapier guides the weft yarn onto the two sets of spacer yarns. Spacer yarn I is lifted to the top layer of the weave opening. The reed beats the weft, and the two double-heddle frames perform one heddle change, and the upper and lower layers of fabric are interlaced once, forming a rectangular unit.

[0075] Step 5: Functional Unit Weaving: The middle rapier II introduces the weft yarn between the upper and lower layers of fabric. The reed beats the weft, and the two single-heddle frames perform a heddle change, achieving one interweaving of the functional weft yarn and the spacer yarn. The same method is used to perform another interweaving of the functional weft yarn and the spacer yarn. Then, the upper rapier introduces the weft yarn between the two sets of upper warp yarns, and the lower rapier introduces the weft yarn between the two sets of lower warp yarns. The reed beats the weft; the two double-heddle frames perform a heddle change, achieving one interweaving of the upper and lower layers of fabric. The same method is used to complete another interweaving of the upper and lower layers of fabric. The reed beats the weft; the two single-heddle frames perform a heddle change, achieving one interweaving of the spacer fabric. This forms a functional unit.

[0076] Step 6: Weaving of the two-unit three-dimensional woven spacer fabric: Steps 4 and 5 are performed alternately or in different ways to weave the two-unit three-dimensional woven spacer fabric.

[0077] Step 7: Resin preparation: Mix the resin and curing agent according to the ratio and stir for 5-15 minutes to ensure that they are evenly mixed;

[0078] Step 8: Resin Impregnation: Place the fabric on a mold coated with release agent; use a dropper to evenly apply the resin solution in an "S" shape along the weft direction once, then evenly apply it in an "S" shape along the warp direction once. Let it stand for 30-300 seconds to allow it to penetrate and impregnate. Turn the fabric over and use a dropper to evenly apply the resin solution in an "S" shape along the weft direction once, then evenly apply it in an "S" shape along the warp direction once. Let it stand for 30-300 seconds to allow it to penetrate and impregnate. Repeat the above operation until the resin solution content is 30%-80% of the total mass and the fabric content is 20%-70% of the total mass.

[0079] Step 9: Composite molding: Place the resin-impregnated fabric into an oven and pre-cur and cure it at 50-320℃ for 3-12 hours to obtain a two-unit three-dimensional woven spacer fabric reinforced composite material.

[0080] The preparation method of a two-unit three-dimensional woven spacer fabric reinforced composite material of the present invention shall meet one or more of the following conditions:

[0081] Condition 1 is that in step 1, the yarn is one or more of chemical fibers, natural fibers, inorganic fibers, and functional yarns;

[0082] Condition 2 is that in step 1, the fabric structure, warp and weft density, spacing yarn density, width, length, spacing height, and weaving tension are designed according to actual requirements;

[0083] Condition 3 is that in step 2, the warp threading pattern is that the nth warp of each upper layer of warp is threaded through the upper heddle eye of the nth heddle wire in its corresponding heddle frame, and the nth warp of each lower layer of warp is threaded through the lower heddle eye of the nth heddle wire in its corresponding heddle frame, wherein the rightmost warp is the first warp.

[0084] Condition 4 is that in step 2, the threading pattern of the spacer yarns is such that the nth yarn of each group of spacer yarns is threaded through the nth heddle wire of its corresponding heddle frame; the nth yarn of spacer yarn (Ⅰ) passes between the (2n-1)th and (2n-2)th heddle wires of the double heddle frame; the nth yarn of spacer yarn (Ⅱ) passes between the 2nth and (2n-1)th heddle wires of the double heddle frame; where the rightmost spacer yarn is the first yarn;

[0085] Condition 5 is that in step 4, the rectangular unit is perpendicular to the upper and lower fabric layers.

[0086] Condition 6 is that in step 5, the number of interlacing times between the functional weft yarn and the spacer yarn is 2n;

[0087] Condition 7 is that in step 5, the functional weft yarn and the spacer yarn interlacing unit are parallel to the upper and lower fabric layers.

[0088] Condition 8 is that in step 5, the height of the interlacing unit of the functional weft yarn and the spacer yarn can be controlled by the tension of the upper and lower sets of spacer yarns; or it can be controlled by adding an external spacer device.

[0089] Condition 9 is that in step 5, the position of the interlacing unit of the functional weft yarn and the spacer yarn is at the halfway point between the upper and lower fabrics;

[0090] Condition 10 is that in step 5, the functional weft yarn and the spacer yarn interweave twice to form the minimum cycle; the upper and lower layers of fabric interweave once to form the minimum cycle.

[0091] Condition 11 states that in step 5, different functional unit groups with different combinations of cycle counts can be designed according to actual needs.

[0092] Condition 12 is that in step 6, the alternation pattern of rectangular units and functional units can be designed according to actual needs to form a two-unit three-dimensional woven spacer fabric with different cycle patterns.

[0093] Condition 13 is that in step 7, the resin is one or more of epoxy resin, vinyl resin, polyimide resin and phenolic resin.

[0094] Condition 14 is that in step 7, the resin mass fraction is 65%-85% and the curing agent mass fraction is 15%-35%.

[0095] More preferably, the upper weft yarn, lower weft yarn, inner weft yarn, and spacer yarn are selected from one or more of glass fiber, aramid, carbon fiber, ultra-high molecular weight polyethylene fiber, ramie, jute, flax, polypropylene fiber, polyethylene fiber, polyester, and acrylic fiber; the functional weft yarn is selected from one or more of copper wire fiber, stainless steel fiber, silver-plated yarn, carbon nanotube yarn, carbon nanotube coated yarn, carbon fiber, graphene fiber, Mxene coated yarn, carbon nanotube membrane roll yarn, and microfluidic tube.

[0096] Example 1

[0097] Step 1: Process Preparation: Except for the functional weft yarn, all yarns are made of 1500D aramid produced by DuPont; the functional weft yarn is made of self-made 300tex carbon nanotube coated glass fiber bulky yarn; the upper and lower layers of fabric are both plain weave; the warp density of the upper and lower layers is determined to be 50 threads / 10cm; the weft density of the upper and lower layers is determined to be 75 threads / 10cm; the spacing yarn density is determined to be 23.5 threads / 10cm; the width is determined to be 20cm, the length to be 100cm, and the spacing height to be 20mm; the pretension of the upper and lower spacing yarns is determined to be 5N; prepare a steel reed with a reed size of 25.5, prepare two double-harness heddle frames and two single-harness heddle frames, and set the distance between the upper and lower layers to 20mm using the spacing device.

[0098] Step 2: Threading the yarn: Using the rightmost yarn and heddle as the first yarn and heddle; thread one set of upper warp 1 and lower warp 2 onto a double-heddle frame according to a pattern; thread another set of upper warp 1 and lower warp 2 onto another double-heddle frame according to a pattern. The threading pattern is that the nth warp of each set of upper warp 1 is threaded through the upper heddle eye of the nth heddle in its corresponding heddle frame, and the nth warp of each set of lower warp 1 should be threaded through the lower heddle eye of the nth heddle in its corresponding heddle frame; thread the two sets of spacer yarns onto two single-heddle frames according to a pattern. On the heddle frame, the threading rule for the spacer yarns is as follows: the nth yarn of each group of spacer yarns should be threaded through the nth heddle wire of its corresponding heddle frame. The nth yarn of spacer yarn I should pass between the (2n-1)th and (2n-2)th heddle wires of the double heddle frame, and the nth yarn of spacer yarn II should pass between the 2nth and (2n-1)th heddle wires of the double heddle frame. The upper and lower weft yarns are threaded onto the upper and lower rapiers respectively. The inner weft yarns and functional weft yarns are threaded onto the middle rapier I and middle rapier II respectively.

[0099] Step 3: Weaving of the spacer fabric structure: The upper rapier guides the upper weft yarn 3 between the two sets of upper warp yarns, and the lower rapier guides the lower weft yarn 4 between the two sets of lower warp yarns. The spacer is placed between the upper and lower warp yarns. The reed beats the weft once. The two double-heddle frames and the two single-heddle frames are changed once each. The weft is then returned to form a normal woven spacer fabric structure unit.

[0100] Step 4: Rectangular Unit Weaving: Lift both sets of spacer yarns to the top layer, introduce the upper layer weft yarn with the upper rapier, and lower one set of spacer yarns to the bottom layer; the middle rapier I introduces the inner layer weft yarn between the two sets of spacer yarns, the reed beats the weft, the two single-heald frames change heddles once, the reed retreats once, completing one layer of interlacing of inner layer weft yarn and spacer yarn. Repeat this process 13 times to complete one layer of interlacing of inner layer weft yarn and spacer yarn; then lower both sets of spacer yarns to the bottom layer, introduce the lower layer weft yarn with the lower rapier, lift one set of spacer yarns to the top layer, beat the weft with the reed, the two double-heald frames change heddles once, completing one layer of interlacing of upper and lower layers of fabric, the reed retreats once, forming a rectangular unit;

[0101] Step 5: Functional Unit Weaving: The middle rapier II introduces the functional weft yarn between two sets of spacer yarns, the reed beats the weft, and the two single-heddle frames perform one heddle change, achieving one interweaving of the functional weft yarn and spacer yarn; the same method is used to perform another interweaving of the functional weft yarn and spacer yarn; then the upper rapier introduces the weft yarn between two sets of upper warp yarns, and the lower rapier introduces the weft yarn between two sets of lower warp yarns; the reed beats the weft; the two double-heddle frames perform one heddle change, achieving one interweaving of the upper and lower fabrics; the same method is used to complete another interweaving of the upper and lower fabrics; the reed beats the weft; the two single-heddle frames perform one heddle change, achieving one interweaving of the spacer fabric; forming one functional unit; repeat this step once to form two functional units;

[0102] Step 6: Weaving of the two-unit three-dimensional woven spacer fabric: Steps 4 and 5 are performed alternately, stopping when the fabric width reaches 100cm. The final product is a two-unit three-dimensional woven spacer fabric.

[0103] Example 2

[0104] Step 1: Fabric preparation: The dual-unit three-dimensional woven spacer fabric described in Example 1 is selected as the reinforcing material.

[0105] Step 2: Resin Preparation: Use JL-235 bisphenol A epoxy resin and JH-242 amine curing agent (produced by Hangzhou Mojiafa New Materials (Suzhou) Co., Ltd.) as the matrix materials, and LOCTITE 55-NC release agent. Prepare two clean, flat glass plates and four 20mm high support pillars. Apply the release agent evenly to one side of each glass plate and allow it to dry at room temperature for 10-20 minutes. Mix the resin and curing agent according to a mass ratio of 100:33 (epoxy resin:curing agent). Stir the resin and curing agent mixture at 20℃ for 10 minutes to ensure uniform mixing.

[0106] Step 3: Resin Impregnation: Place 100g of fabric on a glass plate with the release agent applied to the side. Using a dropper, apply the resin-curing agent mixture described in Step 2 evenly in an "S" shape along the weft direction to the surface of the upper fabric once, then apply it evenly in an "S" shape along the warp direction once. Let it stand for 30 seconds to allow it to penetrate and impregnate. Turn the fabric over and use a dropper to apply the resin-curing agent mixture described in Step 2 evenly in an "S" shape along the weft direction to the surface of the lower fabric once, then apply it evenly in an "S" shape along the warp direction once. Let it stand for 30 seconds to allow it to penetrate and impregnate. The total amount of resin-curing agent mixture used is 334.78g. Place four supports at the four corners of the glass plate, and place another glass plate with the release agent applied to the side facing down on top of the four supports.

[0107] Step 4: Composite molding: Place the resin-impregnated fabric from Step 3 into an oven at 50°C for 1 hour for pre-curing. Turn it over and place it back into the oven for 2 hours of pre-curing at 50°C. Then raise the oven temperature to 70°C and cure for 7 hours to obtain a dual-unit three-dimensional woven spacer fabric reinforced composite material.

Claims

1. A two-unit three-dimensional woven spacer fabric, characterized in that, The fabric comprises warp yarns, weft yarns, and spacer yarns. The warp yarns include upper and lower warp yarns; the weft yarns include upper and lower weft yarns, inner-layer weft yarns located between the upper and lower weft yarns, and functional weft yarns; the spacer yarns include spacer yarn I and spacer yarn II. Two sets of upper warp yarns interweave with the upper weft yarns to form an upper layer fabric; two sets of lower warp yarns interweave with the lower weft yarns to form a lower layer fabric; spacer yarn I and spacer yarn II interweave with the upper and lower weft yarns to form a spacer fabric; the inner-layer weft yarns interweave with the spacer yarns to form a rectangular structural unit; and the functional weft yarns interweave with the spacer yarns to form a functional unit. By changing the heald frame movement pattern, the combined weaving of rectangular units and functional units is achieved. The rectangular unit divides the continuous cavity, separating multiple independent groups of functional units, thus achieving the separation and protection of the functional units.

2. The dual-unit three-dimensional woven spacer fabric as described in claim 1, characterized in that, The warp yarns, upper weft yarns, lower weft yarns, inner weft yarns, and spacer yarns are one or more of natural fibers, chemical fibers, and inorganic fibers.

3. The dual-unit three-dimensional woven spacer fabric as described in claim 2, characterized in that, The natural fiber is one or more of ramie, jute, and flax; the chemical fiber is one or more of aramid fiber, polypropylene fiber, polyethylene fiber, polyester, and acrylic fiber; and the inorganic fiber is one or more of glass fiber, carbon fiber, quartz fiber, basalt fiber, and ceramic fiber.

4. The dual-unit three-dimensional woven spacer fabric as described in claim 1, characterized in that, The functional weft yarn is one or more of the following: conductive yarn, electric heating yarn, sensing yarn, and thermally conductive yarn.

5. The dual-unit three-dimensional woven spacer fabric as described in claim 4, characterized in that, The conductive yarn is one or more of copper wire fiber, stainless steel fiber, carbon nanotube yarn, and silver-plated yarn; the electrothermal yarn is one or more of carbon fiber, graphene fiber, Mxene-coated yarn, and carbon nanotube-coated yarn; the sensing yarn is one or more of carbon nanotube yarn, silver-plated nylon yarn, and graphene yarn; and the thermally conductive yarn is one or more of carbon nanotube yarn, stainless steel fiber, and microfluidic tube.

6. A method for preparing a two-unit three-dimensional woven spacer fabric as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Process preparation: Select each group of yarns according to the required properties of the fabric. The fineness of the yarns is 100-1200 tex. Determine the weave structure of the upper and lower layers to be one of plain weave, twill weave, satin weave, or variations thereof; warp density should be 30-100 ends / 10cm; weft density should be 20-150 ends / 10cm; spacer yarn density should be 15-50 ends / 10cm; width should be 20-200cm; spacer height should be 4-30mm; weaving tension should be controlled at 5-10N; prepare the appropriate reeds and heald frames. Step 2: Yarn threading: Thread one set of upper and lower warp yarns onto a double-heddle frame according to a pattern; thread another set of upper and lower warp yarns onto another double-heddle frame according to a pattern; the two double-heddle frames control the interweaving of the upper and lower fabrics; thread two sets of spacer yarns onto two single-heddle frames according to a pattern; the two single-heddle frames control the interweaving of the spacer yarns; thread the upper and lower weft yarns onto the upper and lower rapiers respectively; thread the inner-layer weft yarns and functional weft yarns onto the middle rapier I and middle rapier II respectively; Step 3: Weaving of the spacer fabric structure: The upper rapier guides the weft yarn between two sets of upper warp yarns, and the lower rapier guides the weft yarn between two sets of lower warp yarns. The height of the spacer device is set to 4-30mm to control the spacing after the upper and lower yarns interweave, which is the height of the spacer fabric; the reed beats the weft; the two double-heald frames and the two single-heald frames are replaced with heddles respectively to form a normal machine-woven spacer fabric structure unit; Step 4: Rectangular Unit Weaving: For ease of description, assume that spacer yarn I is at the top layer of the weave and spacer yarn II is at the bottom layer of the weave; lift spacer yarn II to the top layer of the weave, making it flush with spacer yarn I; the upper rapier guides the weft yarn under the two sets of spacer yarns; lower spacer yarn II to the bottom layer of the weave; the middle rapier guides the weft yarn between the two sets of spacer yarns, the reed beats the weft, and the two single-heald frames perform one heald change, realizing one layer of interlacing of weft yarn and spacer yarn; repeat the same method to interlacing weft yarn and spacer yarn until the length of the plain weave fabric reaches the spacer height; for ease of description, assume that the number of repetitions is 2n, then spacer yarn I is at the top layer of the weave and spacer yarn II is at the bottom layer of the weave; lower spacer yarn I to the bottom layer of the weave, making it flush with spacer yarn II; The lower rapier guides the weft yarn onto the two sets of spacer yarns; spacer yarn I is lifted to the top layer of the weft; the reed beats the weft, and the two double-heddle frames change heddles once, and the upper and lower layers of fabric are interwoven once; forming a rectangular unit; Step 5: Functional Unit Weaving: The middle rapier II introduces the weft yarn between the upper and lower layers of fabric. The reed beats the weft, and the two single-heddle frames perform a heddle change, achieving one interweaving of the functional weft yarn and the spacer yarn. The same method is used to perform another interweaving of the functional weft yarn and the spacer yarn. Then, the upper rapier introduces the weft yarn between the two sets of upper warp yarns, and the lower rapier introduces the weft yarn between the two sets of lower warp yarns. The reed beats the weft; the two double-heddle frames perform a heddle change, achieving one interweaving of the upper and lower layers of fabric. The same method is used to complete another interweaving of the upper and lower layers of fabric. The reed beats the weft; the two single-heddle frames perform a heddle change, achieving one interweaving of the spacer fabric. This forms a functional unit. Step 6: Weaving of the two-unit three-dimensional woven spacer fabric: Steps 4 and 5 are performed alternately or in different ways to weave the two-unit three-dimensional woven spacer fabric.

7. The method for preparing a two-unit three-dimensional woven spacer fabric as described in claim 6, characterized in that, It meets one or more of the following conditions: Condition 1 is that in step 1, the warp yarn, upper weft yarn, lower weft yarn, inner weft yarn, and spacer yarn are one or more of natural fibers, chemical fibers, and inorganic fibers; and the functional weft yarn is one or more of conductive yarn, electrothermal yarn, sensing yarn, and thermally conductive yarn. Condition 2 is that the fabric structure, warp and weft density, spacing yarn density, width, length, spacing height, and weaving tension in step 1 are designed according to actual requirements; Condition 3 is that in step 2, the warp threading pattern is that the nth warp of each upper layer of warp is threaded through the upper heddle eye of the nth heddle wire in its corresponding heddle frame, and the nth warp of each lower layer of warp is threaded through the lower heddle eye of the nth heddle wire in its corresponding heddle frame, wherein the rightmost warp is the first warp. Condition 4 is that in step 2, the threading pattern of the spacer yarns is such that the nth yarn of each group of spacer yarns is threaded through the nth heddle wire of its corresponding heddle frame; the nth yarn of spacer yarn I passes between the (2n-1)th and (2n-2)th heddle wires of the double heddle frame; the nth yarn of spacer yarn II passes between the 2nth and (2n-1)th heddle wires of the double heddle frame; where the rightmost spacer yarn is considered the first yarn; Condition 5 is that in step 4, the rectangular unit is perpendicular to the upper and lower fabric layers. Condition 6 is that in step 5, the number of interlacing times between the functional weft yarn and the spacer yarn is 2n; Condition 7 is that in step 5, the functional weft yarn and the spacer yarn interlacing unit are parallel to the upper and lower fabric layers. Condition 8 is that in step 5, the height of the interlacing unit of the functional weft yarn and the spacer yarn is controlled by the tension of the upper and lower sets of spacer yarns; it can also be controlled by adding an external spacer device. Condition 9 is that in step 5, the position of the interlacing unit of the functional weft yarn and the spacer yarn is at the halfway point between the upper and lower fabrics; Condition 10 is that in step 5, the functional weft yarn and the spacer yarn interweave twice to form the minimum cycle; the upper and lower layers of fabric interweave once to form the minimum cycle. Condition 11 is that in step 5, different functional unit groups with different combinations of loop counts are designed according to actual needs; Condition 12 is that in step 6, the alternation pattern of rectangular units and functional units is designed according to actual needs to form a two-unit three-dimensional woven spacer fabric with different cycle patterns.

8. A dual-unit three-dimensional woven spacer fabric reinforced composite material, characterized in that, It is formed by combining a dual-unit three-dimensional woven spacer fabric as described in any one of claims 1 to 5 with a resin solution; wherein the resin solution is one or more of epoxy resin, vinyl resin, polyimide resin and phenolic resin.

9. A method for preparing a two-unit three-dimensional woven spacer fabric reinforced composite material as described in claim 8, characterized in that, Includes the following steps: Step 1: Process preparation: Select each group of yarns according to the required properties of the fabric. The fineness of the yarns is 100-1200 tex. Determine the weave structure of the upper and lower layers to be one of plain weave, twill weave, satin weave, or variations thereof; warp density should be 30-100 ends / 10cm; weft density should be 20-150 ends / 10cm; spacer yarn density should be 15-50 ends / 10cm; width should be 20-200cm; spacer height should be 4-30mm; weaving tension should be controlled at 5-10N; prepare the appropriate reeds and heald frames. Step 2: Yarn threading: Thread one set of upper and lower warp yarns onto a double-heddle frame according to a pattern; thread another set of upper and lower warp yarns onto another double-heddle frame according to a pattern; the two double-heddle frames control the interweaving of the upper and lower fabrics; thread two sets of spacer yarns onto two single-heddle frames according to a pattern; the two single-heddle frames control the interweaving of the spacer yarns; thread the upper and lower weft yarns onto the upper and lower rapiers respectively; thread the inner-layer weft yarns and functional weft yarns onto the middle rapier I and middle rapier II respectively; Step 3: Weaving of the spacer fabric structure: The upper rapier guides the weft yarn between two sets of upper warp yarns, and the lower rapier guides the weft yarn between two sets of lower warp yarns. The height of the spacer device is set to 4-30mm to control the spacing after the upper and lower yarns interweave, which is the height of the spacer fabric; the reed beats the weft; the two double-heald frames and the two single-heald frames are replaced with heddles respectively to form a normal machine-woven spacer fabric structure unit; Step 4: Rectangular Unit Weaving: For ease of description, assume that spacer yarn I is at the top layer of the weave and spacer yarn II is at the bottom layer of the weave; lift spacer yarn II to the top layer of the weave, making it flush with spacer yarn I; the upper rapier guides the weft yarn under the two sets of spacer yarns; lower spacer yarn II to the bottom layer of the weave; the middle rapier guides the weft yarn between the two sets of spacer yarns, the reed beats the weft, and the two single-heald frames perform one heald change, realizing one layer of interlacing of weft yarn and spacer yarn; repeat the same method to interlacing weft yarn and spacer yarn until the length of the plain weave fabric reaches the spacer height; for ease of description, assume that the number of repetitions is 2n, then spacer yarn I is at the top layer of the weave and spacer yarn II is at the bottom layer of the weave; lower spacer yarn I to the bottom layer of the weave, making it flush with spacer yarn II; The lower rapier guides the weft yarn onto the two sets of spacer yarns; spacer yarn I is lifted to the top layer of the weft; the reed beats the weft, and the two double-heddle frames change heddles once, and the upper and lower layers of fabric are interwoven once; forming a rectangular unit; Step 5: Functional Unit Weaving: The middle rapier II introduces the weft yarn between the upper and lower layers of fabric. The reed beats the weft, and the two single-heddle frames perform a heddle change, achieving one interweaving of the functional weft yarn and the spacer yarn. The same method is used to perform another interweaving of the functional weft yarn and the spacer yarn. Then, the upper rapier introduces the weft yarn between the two sets of upper warp yarns, and the lower rapier introduces the weft yarn between the two sets of lower warp yarns. The reed beats the weft; the two double-heddle frames perform a heddle change, achieving one interweaving of the upper and lower layers of fabric. The same method is used to complete another interweaving of the upper and lower layers of fabric. The reed beats the weft; the two single-heddle frames perform a heddle change, achieving one interweaving of the spacer fabric. This forms a functional unit. Step 6: Weaving of the two-unit three-dimensional woven spacer fabric: Steps 4 and 5 are performed alternately or in different ways to weave the two-unit three-dimensional woven spacer fabric. Step 7: Resin preparation: Mix the resin and curing agent according to the ratio and stir for 5-15 minutes to ensure that they are evenly mixed; Step 8: Resin Impregnation: Place the fabric on a mold coated with release agent; use a dropper to evenly apply the resin solution in an "S" shape along the weft direction once, then evenly apply it in an "S" shape along the warp direction once. Let it stand for 30-300 seconds to allow it to penetrate and impregnate. Turn the fabric over and use a dropper to evenly apply the resin solution in an "S" shape along the weft direction once, then evenly apply it in an "S" shape along the warp direction once. Let it stand for 30-300 seconds to allow it to penetrate and impregnate. Repeat the above operation until the resin solution content is 30%-80% of the total mass and the fabric content is 20%-70% of the total mass. Step 9: Composite molding: Place the resin-impregnated fabric into an oven and pre-cur and cure it at 50-320℃ for 3-12 hours to obtain a two-unit three-dimensional woven spacer fabric reinforced composite material.

10. The method for preparing the dual-unit three-dimensional woven spacer fabric reinforced composite material as described in claim 9, characterized in that, It meets one or more of the following conditions: Condition 1 is that in step 1, the warp yarn, upper weft yarn, lower weft yarn, inner weft yarn, and spacer yarn are one or more of natural fibers, chemical fibers, and inorganic fibers; and the functional weft yarn is one or more of conductive yarn, electrothermal yarn, sensing yarn, and thermally conductive yarn. Condition 2 is that the fabric structure, warp and weft density, spacing yarn density, width, length, spacing height, and weaving tension in step 1 are designed according to actual requirements; Condition 3 is that in step 2, the warp threading pattern is that the nth warp of each upper layer of warp is threaded through the upper heddle eye of the nth heddle wire in its corresponding heddle frame, and the nth warp of each lower layer of warp is threaded through the lower heddle eye of the nth heddle wire in its corresponding heddle frame, wherein the rightmost warp is the first warp. Condition 4 is that in step 2, the threading pattern of the spacer yarns is such that the nth yarn of each group of spacer yarns is threaded through the nth heddle wire of its corresponding heddle frame; the nth yarn of spacer yarn I passes between the (2n-1)th and (2n-2)th heddle wires of the double heddle frame; the nth yarn of spacer yarn II passes between the 2nth and (2n-1)th heddle wires of the double heddle frame; where the rightmost spacer yarn is considered the first yarn; Condition 5 is that in step 4, the rectangular unit is perpendicular to the upper and lower fabric layers. Condition 6 is that in step 5, the number of interlacing times between the functional weft yarn and the spacer yarn is 2n; Condition 7 is that in step 5, the functional weft yarn and the spacer yarn interlacing unit are parallel to the upper and lower fabric layers. Condition 8 is that in step 5, the height of the interlacing unit of the functional weft yarn and the spacer yarn is controlled by the tension of the upper and lower sets of spacer yarns; it can also be controlled by adding an external spacer device. Condition 9 is that in step 5, the position of the interlacing unit of the functional weft yarn and the spacer yarn is at the halfway point between the upper and lower fabrics; Condition 10 is that in step 5, the functional weft yarn and the spacer yarn interweave twice to form the minimum cycle; the upper and lower layers of fabric interweave once to form the minimum cycle. Condition 11 is that in step 5, different functional unit groups with different combinations of loop counts are designed according to actual needs; Condition 12 is that in step 6, according to actual needs, the alternation pattern of rectangular units and functional units is designed to form a double-unit three-dimensional woven spacer fabric with different cycle patterns. Condition 13 is that in step 7, the resin is one or more of epoxy resin, vinyl resin, polyimide resin and phenolic resin; Condition 14 is that in step 7, the resin mass fraction is 65%-85% and the curing agent mass fraction is 15%-35%.

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