Tensile sample of electric heating composite material under continuous electrification and preparation method of tensile sample

Abstract

The invention relates to a tensile sample of an electric heating composite material under continuous electrification. The tensile sample comprises three layers of composite materials, the middle layer of the three-layer composite material is an electric heating fabric, the upper layer and the lower layer are both high-performance fiber prepreg, and the upper layer and the lower layer are symmetrical about the middle layer in the thickness direction; the electric heating fabric comprises insulating yarns, a base fabric and a plurality of electric heating elements arranged in parallel, and the electric heating fabric is provided with electrode leads extending out of the two ends of the electric heating fabric; reinforcing sheets are arranged at the edges of the outer side surfaces of the upper layer and the lower layer of the three-layer composite material; the invention also comprises a preparation method of the sample, which comprises the following steps: S1, weaving the electric heating fabric; s2, making a bulk sample of the electric heating composite material; s3, reinforcing pieces are pasted; s4, cutting a material bulk sample; and S5, connecting a power supply. The sample structure can be used for anti-icing and deicing scenes of lightweight aircrafts, an effective means is provided for obtaining mechanical property data of an electric heating composite material in advance under the scene that the electric heating composite material is continuously electrified, the operation is convenient, and the sample stability is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation methods of functional composite materials, and particularly relates to a tensile specimen of an electrothermal composite material under continuous power supply and a preparation method thereof. Background Art

[0002] The mechanical properties of electrothermal composite materials determine the load-bearing performance of aircraft components. At present, the tensile property tests of fiber-reinforced resin matrix composite materials mostly refer to GB / T 3354-2014 "Test Method for Tensile Properties of Oriented Fiber Reinforced Polymer Matrix Composite Materials" and ASTM D3039 / D3039M-07 "Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials". The two test standards disclose that the form of the tensile specimen of the composite material laminate is a straight bar type.

[0003] Patent texts with publication numbers such as CN116008033A, CN115723390A, CN104087786B, CN 108642893A, etc. disclose several preparation methods for electrothermal composite materials or tensile specimens at room temperature. Compared with the tensile property test method at room temperature, in the tensile property test of electrothermal composite materials under continuous power supply, external power sources need to be connected to both ends of the tensile specimen to achieve continuous power supply. The preparation of the tensile specimen is the key to the tensile property test of electrothermal composite materials under continuous power supply. However, the operation processes of the existing tensile specimen preparation methods are generally relatively complex, and there is currently no preparation method for stretching the specimen during the electrothermal process and ensuring the performance of the specimen. Summary of the Invention

[0004] The present invention provides a tensile specimen of an electrothermal composite material under continuous power supply and a preparation method thereof to solve the technical problems existing in the known technology, which can pre-test the mechanical property data of electrothermal composite materials in the scenario of continuous power supply, and has the characteristics of convenient operation and good specimen stability.

[0005] The present invention includes the following technical solutions: A tensile specimen of an electrothermal composite material under continuous power supply, comprising three layers of composite materials; the middle layer of the three layers of composite materials is an electric heating fabric, and the upper and lower layers are both high-performance fiber prepregs, and the upper and lower layers are symmetric about the middle layer in the thickness direction; the electric heating fabric includes insulating yarns, a base fabric, and a plurality of electrically heating elements arranged in parallel, and the electric heating fabric is provided with electrode leads extending from both ends thereof; reinforcing sheets are arranged at the outer side edges of the upper and lower layers of the three layers of composite materials.

[0006] Further, the thickness of the electric heating fabric is 0.20 - 0.70 mm; the thickness of the high-performance fiber prepregs in the upper and lower layers is 0.80 - 1.20 mm. The high-performance fiber prepregs include glass fiber / epoxy prepregs and carbon / epoxy prepregs.

[0007] Furthermore, when the electrothermal fabric is made by the stitch embroidery method, the electrothermal elements are arranged in a sine wave pattern in the plane direction and fixed on the base fabric with insulating sewing threads. The sine wave pattern design does not come loose due to high-frequency vibration.

[0008] Furthermore, when the electrothermal fabric is made by the co-weaving method, the electrothermal elements and insulating yarns are woven together to form the electrothermal fabric. The raw materials required for the electrothermal fabric vary depending on the weaving method. In the co-weaving method, it includes knitting methods, weaving methods, etc.

[0009] Furthermore, when the electrothermal fabric is made by the knitting method, the electrothermal elements and insulating yarns are looped through each other; when the electrothermal fabric is made by the weaving method, the electrothermal elements are arranged in a straight line and the adjacent electrothermal elements are spaced equally.

[0010] Furthermore, the optional types of the electrothermal elements include metal wires, carbon fibers, and PTC conductive materials; among them, the metal wires include nickel-chromium alloy wires, copper-nickel alloy wires, pure copper wires, and stainless steel wires. The overall length of the electrothermal element exceeds the length of the electrothermal fabric.

[0011] Furthermore, the base fabric includes glass fiber fabric, polyester fabric, and polyamide fabric; the insulating sewing threads include polyester and aramid; the insulating yarns include polyester, aramid, and polyimide fibers.

[0012] The preparation method of the above tensile specimen includes the following steps: S1. Weave the electrothermal fabric, and reserve electrode leads at both ends of the electrothermal fabric along the tensile loading direction for subsequent connection to the power supply for continuous power supply; S2. Make a large sample of the electrothermal composite material, and composite three layers of composite materials. During the composite molding process, design a resin absorbent material to protect the electrode leads reserved at both ends of the electrothermal fabric; S3. Paste reinforcement patches, and paste reinforcement patches on the outer surface edges of the high-performance fiber prepreg for easy clamping by the tensile fixture (after introducing the electrothermal elements, the flatness of the electrothermal composite material decreases, and the positions of the reinforcement patches need to be designed on the upper and lower surfaces of the overall large sample for easy clamping by the tensile fixture); S4. Cut the large sample of the material, cut the large sample of the electrothermal composite material from the position between the reinforcement patches and ensure the integrity of the electrothermal elements and electrode leads during cutting; S5. Connect the power supply, fix several electrode leads at both ends of each cut tensile specimen into a group and then connect the power supply for continuous power supply.

[0013] Furthermore, the composite molding process in S2 includes vacuum bag molding process, autoclave molding process, hot pressing molding process, and compression molding process.

[0014] Furthermore, during the composite molding process of S2, the adhesive absorbing material is designed to be straight strip-shaped and completely covers the electrode lead to prevent the electrode lead from contacting the resin and causing solidification; the adhesive absorbing material includes adhesive absorbing felt, filter paper, and polyester non-woven fabric.

[0015] Furthermore, the upper and lower adjacent reinforcing sheets in S3 are symmetrical about the electric heating fabric, and the corresponding reinforcing sheets at the left and right positions on the same plane are symmetrical about the center line of the electric heating composite material; the reinforcing sheets are parallel to the arrangement direction of the electric heating elements, arranged at both ends of the electric heating composite material, close to the electrode leads; the area on the outer surface of the high-performance fiber prepreg designed with the reinforcing sheet is polished and cleaned, and then evenly coated with adhesive, and the surface of the reinforcing sheet pasting part is cleaned, evenly coated with adhesive, and then pasted to the corresponding position.

[0016] Furthermore, when the electrode lead is directly connected to the power source, the specific process of fixing in S5 is to use insulating glue to fix the electrode lead with the insulating skin, and the length of the insulating skin is 6-7 cm extending outward from the end of the reinforcing sheet.

[0017] Furthermore, when the electrode lead is indirectly connected to the power supply, the specific process of fixing in S5 is to cover the electrode lead by sewing a bus bar, connect the power supply through the bus bar for continuous power supply, and the length of the bus bar is 2 to 3 cm.

[0018] The present invention has the following advantages and positive effects:

[0019] 1. The tensile specimen recorded in the present invention has an intermediate layer of electrically heated fabric, and the upper and lower layers are both high-performance fiber prepregs. After being connected to a power source, it has conductive and electrothermal properties in both the initial and stretched states, and can be used in lightweight aircraft deicing scenarios.

[0020] 2. The outer layer of the tensile specimen recorded in the present invention uses high-performance fiber prepreg, which can effectively reduce the exposed wear of the electric heating element during the stretching process, and ensure the stability of the electrical heating of the tensile specimen during the tensile performance test.

[0021] 3. The tensile test specimens recorded in the present invention are tested for tensile properties under continuous power-on conditions, and can in situ characterize and analyze the tensile properties of the electrothermal composite material under the working temperature-raising state. It has sufficient strength, stiffness, and impact resistance, and can resist low-temperature icing. After power-on, it quickly heats up to achieve the purpose of anti-icing, thus achieving a balance between mechanical properties and electrothermal functions.

[0022] 4. The tensile test specimens described in the present invention show certain stability, high elongation at break, and can withstand deformation, such as stretching, bending, twisting, etc.

[0023] 5. The tensile specimen preparation method described in the present invention uses a three-layer composite material for composite molding. The different layers are tightly bonded and have electrothermal properties in the thickness direction.

[0024] 6. The tensile specimen preparation method described in the present invention realizes precise control of the surface temperature of the tensile specimen, improving the accuracy and repeatability of the test. In addition, this method can significantly simplify the test process and improve efficiency. It is applicable to the evaluation and research of other mechanical properties of electrothermal composite materials and has the advantage of low cost. Brief Description of the Drawings

[0025] Figure 1 is a three-dimensional schematic diagram of the structure of the electrothermal composite material of the present invention;

[0026] Figure 2 is Figure 1 a schematic diagram of the A-A part of

[0027] Figure 3 is a three-dimensional schematic diagram of the large sample structure of the electrothermal composite material in Example 1;

[0028] Figure 4 is a three-dimensional schematic diagram of the tensile specimen of the electrothermal composite material in Example 1;

[0029] Figure 5 is Figure 4 a schematic diagram of the processing process of the B-B part in

[0030] Figure 6 is a schematic diagram of the state of the tensile property test of the electrothermal composite material tensile specimen in Example 1 under continuous power supply;

[0031] Figure 7 is a three-dimensional schematic diagram of the large sample structure of the electrothermal composite material in Example 2;

[0032] Figure 8 is a three-dimensional schematic diagram of the tensile specimen of the electrothermal composite material in Example 2;

[0033] Figure 9 is a schematic diagram of the state of the tensile property test of the electrothermal composite material tensile specimen in Example 2 under continuous power supply;

[0034] Figure 10 is the performance curve of the electrothermal composite material tensile specimen;

[0035] Figure 11 is the temperature nephogram of the tensile property test of the electrothermal composite material tensile specimen under continuous power supply;

[0036] In the figure, 1 - electrically heated fabric; 2 - high-performance fiber prepreg; 3 - electrode lead; 4 - reinforcing sheet; 5 - insulating skin; 6 - insulating glue; 7 - bus bar; 8 - tensile fixture; 9 - infrared thermal imager; 10 - power supply. Detailed implementation mode

[0037] To further disclose the content, features and effects of the invention, the following examples are specifically cited and described in detail with reference to the accompanying drawings. In the description of the following embodiments, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present patent.

[0038] In the description of the following embodiments, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "set" should be understood in a broad sense. For example, it can be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in the present patent can be understood according to specific circumstances.

[0039] Example 1: Refer to the attached Figures 1-6 , a tensile specimen of an electrothermal composite material under continuous power supply (the structural schematic diagram of the electrothermal composite material of the present invention is shown in Figure 1 ), including three layers of composite materials; the middle layer of the three layers of composite materials is an electrically heated fabric 1, and the thickness of the electrically heated fabric 1 is 0.68 mm. The upper layer and the lower layer are both high-performance fiber prepregs 2, and the upper layer and the lower layer are symmetric about the middle layer in the thickness direction; the high-performance fiber prepreg 2 is a glass fiber / epoxy prepreg, with the brand number 6509 / EW250 and a thickness of 0.25 mm.

[0040] The electrically heated fabric 1 includes insulating yarns, a base fabric and a number of electrically heated elements arranged in parallel. The electrically heated elements are nickel-chromium alloy wires with a diameter of 0.08 mm; electrode leads 3 extending from both ends thereof are provided on the electrically heated fabric 1. The base fabric is a glass fiber plain weave fabric with the brand number SW210A-92a. Reinforcing sheets 4 are provided at the outer side edges of the upper layer and the lower layer of the three layers of composite materials.

[0041] The electric heating fabric 1 is made by the sewing and embroidery method. The electric heating elements are arranged in a sine wave pattern in the plane direction and are fixed on the base fabric with insulating sewing threads. The sine wave pattern design does not come loose under high-frequency vibration. The insulating sewing thread is 40S / 2 aramid.

[0042] The specific steps for preparing the above tensile specimens are as follows:

[0043] S1. Weave the electric heating fabric 1, and reserve electrode leads 3 at both ends of the electric heating fabric 1 along the tensile loading direction for subsequent connection to the power supply for continuous power-on. The specific steps include the following:

[0044] S1-1. Design the arrangement of the electric heating elements, and prepare the electric heating fabric using the laying and sewing mechanism; on the plate-making software V6.0 of the laying and sewing machine, the arrangement of the nickel-chromium alloy wire can be designed as a sine wave pattern, with a wavelength of 20 mm, an amplitude of 2 mm, and a spacing of 6.66 mm within one cycle, arranged in parallel, and the stitch pattern of the sewing needle is set as a zigzag. The stitch step length of the sewing thread is set to 3.5 mm, and the wiring speed is 350 r / min;

[0045] S1-2. Sew and embroider. The aramid is sewn into the glass fiber fabric from above, passes through the glass fiber fabric and hooks and interlocks with the bottom aramid, then returns to the upper surface of the glass fiber fabric, and the nickel-chromium alloy wire is fixed on the glass fiber fabric. This is repeated to form the overall structure of the electric heating fabric. The lengths of both ends of the nickel-chromium alloy wire need to exceed the glass fiber fabric, and electrode leads are reserved for connection to the power supply for power-on heating.

[0046] S2. Use the vacuum bag molding process to make a large sample of the electrothermal composite material. The three-layer composite material is composite-molded. During the composite molding process, a resin absorbent material is designed to protect the electrode leads 3 reserved at both ends of the electric heating fabric 1. The resin absorbent material is resin absorbent felt with a density of 150 g / m 2 , and the specific steps include the following:

[0047] S2-1. Vacuum bag layup. Lay the glass fiber / epoxy prepreg on the surface of the steel plate mold at layup angles of 0°, 45°, 0°, and 45° one by one, then lay the electric heating fabric of the same area, reserve the nickel-chromium alloy wire electrode leads at both ends, and then lay the glass fiber / epoxy prepreg one by one in a symmetric form in the thickness direction to form a multi-layer structure;

[0048] S2-2. After adding the adhesive-absorbing material for sealing and then evacuating, cut the adhesive-absorbing felt into straight strips with a size of 7.5 cm × 1.5 cm, and the quantity corresponds to the nickel-chromium alloy wire electrode leads; design the adhesive-absorbing felt to closely adhere to the edge of the glass fiber / epoxy prepreg layer, completely covering and protecting the nickel-chromium alloy wire electrode leads from being cured by the resin in the prepreg. Seal the multi-layer structure with a sealing strip and a vacuum bag, connect the vacuum bag through a breather felt and a conduit, and evacuate the vacuum bag at room temperature for 10 min for pre-compaction with a pressure of -0.1 Mpa; subsequently, evacuate and press again for 20 min;

[0049] S2-3. Heat curing. Put the sealed vacuum bag into an oven for heat curing. The specific curing conditions are as follows: continue to evacuate inside the vacuum bag to maintain a vacuum degree of -0.1 MPa, the heating rate of the oven is 20 °C / h, heat up to 150 °C and then keep warm for 4 h; subsequently, stop heating and stop pressing, cool down with the furnace, take out and demold after cooling down to below 60 °C to obtain a large sample of the electrothermal composite material; the size of the large sample of the electrothermal composite material is 250 mm × 200 mm × 2.65 mm.

[0050] S3. Paste the reinforcement piece 4. Paste the reinforcement piece 4 that is convenient for clamping by the stretching fixture 8 at the outer surface edge of the high-performance fiber prepreg 2; use a hot press to design the positions of the reinforcement pieces on the upper and lower surfaces of the large sample of the electrothermal composite material and paste the reinforcement pieces, as Figure 3 shown; based on the principle that the nickel-chromium alloy wire is complete and unbroken when cutting into a tensile specimen, design the width of one reinforcement piece 4 to include at least 3 parallel-arranged nickel-chromium alloy wires; after grinding and cleaning the areas on both surfaces of the large sample of the electrothermal composite material where the reinforcement piece 4 is to be pasted, evenly apply an adhesive, and then clean the surface of the pasting part of the reinforcement piece 4 and evenly apply an adhesive.

[0051] S4. Cut the large sample of the material. Cut the large sample of the electrothermal composite material at the position between the reinforcement pieces 4 and ensure that the electric heating element and the electrode leads 3 are complete during cutting; use a precision engraving machine to cut the large sample of the electrothermal composite material into tensile specimens according to ASTM D3039 / D3039M-07. The schematic diagram of the tensile specimen of the electrothermal composite material in this embodiment is as Figure 4 shown, and the size of the tensile specimen is 250 mm × 25 mm × 2.65 mm.

[0052] S5. Connect the power supply. Fix several electrode leads 3 at both ends of each cut tensile specimen into a group and then connect the power supply for continuous power-on. In this example, the electrode leads 3 are directly connected to the power supply, and use an insulating glue 6 to fix the insulating skin 5 covering the nickel-chromium alloy wire electrode leads 3. The length of the insulating skin 5 covering extends 6 - 7 cm outward from the end of the reinforcement piece 4. The diameter of the insulating skin 5 is 1.5 mm and the length is 7 cm; the brand of the insulating glue is K-704.

[0053] Schematic diagram of the tensile property test of the electrothermal composite material prepared in this example under continuous power supply is shown in Figure 6 .

[0054] Example 2: Refer to the appendix Figures 7-9 , a tensile specimen of the electrothermal composite material under continuous power supply. The schematic diagram of the specimen structure is as shown in Figure 8 . The electrode lead 3 is indirectly connected to the power supply after sewing and embroidering the bus bar 7. Other structures are basically the same as those in Example 1.

[0055] The specific steps of the preparation method of the above tensile specimen are as follows:

[0056] The specific process of fixing in S5 is to cover the electrode lead 3 by the method of sewing and embroidering the bus bar 7, and connect the power supply through the bus bar 7 for continuous power supply. The length of the bus bar 7 is 2 - 3 cm. The surface thread of the bus bar 7 is made of nickel-chromium alloy wire with a diameter of 0.08 mm, and the bottom thread is 40S / 2 aramid. The arrangement method is a straight line, the stitch step length is set to 1 mm, and the wiring speed is 350 r / min. Except for this, other steps are the same as those in Example 1.

[0057] Schematic diagram of the tensile property test of the electrothermal composite material prepared in this example under continuous power supply is shown in Figure 9 .

[0058] Example 3: Refer to the appendix Figures 3-6 , a tensile specimen of the electrothermal composite material under continuous power supply. The schematic diagram of the specimen structure is as shown in Figure 4 . The electrothermal fabric 1 is woven by the knitting co-weaving method, and the metal wire of the electrothermal element is nickel-chromium alloy wire.

[0059] The specific steps of the preparation method of the above tensile specimen are as follows:

[0060] In S1, the electrothermal fabric 1 is prepared by the knitting co-weaving method, and the electrothermal element and the insulating yarn are threaded through each other to form loops; a computerized flat knitting machine is used, and the stitch density value is set to 70. The nickel-chromium alloy wire and the aramid are plied and arranged in a feeding ratio of 4:2 with the double-strand polyester to be interwoven to weave an electrothermal fabric with a plain stitch structure and a thickness of 0.44 mm. The linear density of the aramid is 45 dtex. The linear density of the polyester is 67.5 dtex. Except for this, other steps are the same as those in Example 1.

[0061] Effect example:

[0062] (1) Tensile-electrothermal property curve

[0063] After connecting the power supply 10 to the electrode leads 3 at both ends of the tensile specimen, the tensile property test is carried out. The tensile property is tested at 2 mm / min by a universal testing machine, and the infrared thermal imager 9 is used to synchronously monitor the change of the highest equilibrium temperature on the surface. The tensile-electrothermal property curve is as shown inFigure 10 as shown

[0064] (2) Temperature cloud map

[0065] The surface temperature change of the tensile specimen of the electrothermal composite material under continuous power-on is monitored by the infrared thermal imager 9, and the experimental results are as Figure 11 shown. During the tensile process, the tensile specimen always maintains uniform temperature and stable electrothermal performance; at the moment of fracture, the mechanical energy of the tensile specimen is converted into internal energy, the temperature at the fracture increases, and the temperature at other positions remains well, demonstrating the reliability of the electrothermal composite material. The results show that when the tensile specimen of the electrothermal composite material of the present invention is stretched under continuous power-on, the surface temperature distribution is uniform, and the tensile performance test can be completely carried out.

[0066] Although the preferred embodiments of the present invention are described above, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. These all belong to the protection scope of the present invention.

Claims

1. A tensile specimen of an electrothermal composite material under continuous power supply, characterized in that: It comprises three layers of composite material; the middle layer of the three layers of composite material is electric heating fabric, the upper layer and the lower layer are both high-performance fiber prepreg, and the upper layer and the lower layer are symmetrical about the middle layer in the thickness direction; the electric heating fabric comprises insulating yarn, base fabric and a plurality of electric heating elements arranged in parallel, and the electric heating fabric is provided with electrode leads extending from both ends thereof; reinforcing sheets are provided at the outer side edges of the upper layer and the lower layer of the three layers of composite material.

2. The electrothermal composite material tensile specimen under continuous power-on according to claim 1, characterized in that: The thickness of the electric heating fabric is 0.20-0.70 mm; the thickness of the upper and lower layers of high-performance fiber prepreg are both 0.80-1.20 mm.

3. The electrothermal composite material tensile specimen under continuous power-on according to claim 1, characterized in that: When the electric heating fabric is made by sewing and embroidery, the electric heating elements are arranged in a sinusoidal wave pattern in a plane direction and fixed to the base fabric by insulating stitching.

4. The electrothermal composite material tensile specimen under continuous power-on according to claim 1, characterized in that: When the electric heating fabric is manufactured by the co-weaving method, the electric heating element and the insulating yarn are woven together to form the electric heating fabric; the co-weaving method is further divided into a knitting method and a weaving method.

5. The method for preparing a tensile specimen of an electrothermal composite material under continuous power-on according to claim 4, characterized in that: When the electric heating fabric is knitted, the electric heating elements and the insulating yarns are interlaced to form loops; when the electric heating fabric is woven, the electric heating elements are arranged in a straight line and the intervals between adjacent electric heating elements are the same.

6. A method for preparing a tensile specimen of an electrothermal composite material under continuous power supply, comprising preparing a tensile specimen as claimed in any one of claims 1 to 5, characterized in that: The following steps are as follows: S1. Weaving electric heating fabrics, and reserving electrode leads at both ends of the electric heating fabrics along the direction of tensile loading; S2. Making a sample of electric heating composite materials, composite-molding the three-layer composite materials, and designing an adhesive-absorbing material to protect the electrode leads reserved at both ends of the electric heating fabrics during the composite molding process; S3. Pasting a reinforcing sheet, and pasting a reinforcing sheet that is easy to clamp with a tensile clamp on the edge of the outer surface of the high-performance fiber prepreg; S4. Cutting the material sample, cutting the electric heating composite material sample from the position between the reinforcing sheets and ensuring that the electric heating elements and the electrode leads are intact during cutting; S5. Connecting the power supply, fixing the electrode leads at both ends of each tensile specimen after cutting into a group, and then connecting the power supply for continuous power supply.

7. The method for preparing a tensile specimen of an electrothermal composite material under continuous power-on according to claim 6, characterized in that: During the composite molding process of S2, the adhesive absorbing material is designed to be straight strip-shaped and completely covers the electrode lead; the adhesive absorbing material includes adhesive absorbing felt, filter paper, and polyester non-woven fabric.

8. The method for preparing a tensile specimen of an electrothermal composite material under continuous power-on according to claim 6, characterized in that: The two adjacent upper and lower reinforcing sheets in S3 are symmetrical about the electric heating fabric, and the corresponding left and right reinforcing sheets located in the same plane are symmetrical about the center line of the electric heating composite material; the reinforcing sheets are parallel to the arrangement direction of the electric heating elements, arranged at both ends of the electric heating composite material, close to the electrode leads; the area on the outer surface of the high-performance fiber prepreg designed with the reinforcing sheet is polished and cleaned, and then evenly coated with adhesive, and the surface of the reinforcing sheet pasting part is cleaned, evenly coated with adhesive, and then pasted to the corresponding position.

9. The method for preparing a tensile specimen of an electrothermal composite material under continuous power-on according to claim 6, characterized in that: When the electrode lead is directly connected to the power source, the specific process of fixing in S5 is to use insulating glue to cover the electrode lead with insulating skin to fix it. The length of the insulating skin is 6-7 cm extending outward from the end of the reinforcing sheet.

10. The method for preparing a tensile specimen of an electrothermal composite material under continuous power-on according to claim 6, characterized in that: When the electrode lead is indirectly connected to the power supply, the specific process of fixing in S5 is to cover the electrode lead by sewing a bus bar, connect the power supply through the bus bar for continuous power supply, and the length of the bus bar is 2 to 3 cm.

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