Composite material heating assembly repair method

Abstract

The application provides a composite material heating assembly repairing method, comprising the following steps: completely removing a planar defect damaged area of a heating assembly, trimming to form a repairing window with a regular geometric shape; cutting a heating assembly patch matching the shape of the repairing window but slightly larger in size, and preparing a Z-direction conductive adhesive film strip with a first preset width; pasting the Z-direction conductive adhesive film strip on the edge of the repairing window to form a conductive connecting ring; covering the heating assembly patch on the repairing window, so that the edge of the heating assembly patch is completely pressed on the suspended Z-direction conductive adhesive film strip; applying a preset pressure on the repairing area for pre-pressing or vacuum pre-pressing, and solidifying the Z-direction conductive adhesive film strip according to a corresponding solidification process, so as to connect the heating assembly and the heating assembly patch. The application can realize low-cost and high-quality repairing of the composite material heating assembly.

Description

Technical Field

[0001] This invention relates to the field of functional composite material repair technology, and more specifically, to a method for repairing composite material heating components. Background Technology

[0002] Structurally conductive heating composite materials, such as electrothermal anti-icing and de-icing components used in aircraft leading edges and wind turbine blades, are inevitably susceptible to localized damage during actual manufacturing, processing, or use due to impacts, scratches, and manufacturing defects. These damages primarily manifest as through-holes, surface pits, and internal or surface microcracks. These components (typically composed of electrodes and heating fabrics) are prone to failure once damage occurs, leading to open circuits or abnormal resistance, which can cause the entire heating area to malfunction.

[0003] Currently, there is a lack of effective on-site repair methods for damage to such functional composite materials. The common practice is to scrap and replace the entire heating assembly, resulting in significant material and economic waste, especially for large components. While some conductive adhesives or coatings exist, they are typically used to repair circuit board conductors and cannot address the core challenge of maintaining mechanical strength and heating uniformity in large-area heating films after repair. Directly using isotropic conductive adhesives for repairs easily leads to current concentration and localized overheating, and the bonding strength at the repair interface often fails to meet the requirements of the structural component. Especially for different types of damage, such as linear cracks and planar holes, existing technologies lack targeted repair strategies, making it difficult to simultaneously guarantee the electrical performance, mechanical performance, and long-term reliability of the repaired component.

[0004] The existing repair methods mainly have the following technical problems:

[0005] 1. Difficulty in balancing function and structural performance: Although ordinary conductive adhesive can temporarily restore conductivity, it has the problem of weak interfacial bonding strength, which cannot meet the mechanical performance requirements of the structural components. At the same time, isotropic conductive adhesive is prone to local current concentration, causing overheating in the repaired area and disrupting the uniformity of heating.

[0006] 2. The repair process is complex and costly: The lack of simple and effective in-situ repair methods means that damaged components often have to be replaced as a whole, resulting in a huge waste of materials and economic losses.

[0007] 3. Poor long-term reliability of repairs: For crack-type damage, simple surface covering cannot prevent its further expansion; for hole-type damage, improper overlapping can easily cause stress concentration, leading to premature failure of the repair structure under thermal cycling or mechanical load. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] The technical problem to be solved by the present invention is that existing repair methods have the problems of difficulty in balancing function and structural performance, complex repair process, high cost, and poor long-term reliability.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] In a first aspect, the present invention provides a method for repairing a composite material heating assembly, comprising the following steps:

[0013] Completely remove the planar defects and damaged areas of the heating component, and trim them to form a repair window with a regular geometric shape;

[0014] Cut a heating component patch that matches the shape of the repair window but is slightly larger in size, and prepare a Z-direction conductive adhesive strip with a first preset width;

[0015] The Z-direction conductive adhesive strip is pasted onto the edge of the repair window, so that half the width of the Z-direction conductive adhesive strip covers the intact heating component at the edge of the repair window, and the other half hangs above the repair window, forming a conductive connection ring.

[0016] Cover the repair window with the heating component patch, so that the edge of the heating component patch is completely pressed against the suspended Z-axis conductive adhesive strip;

[0017] Apply a preset pressure to the repair area for pre-compression or vacuum pre-compression, and cure the Z-direction conductive adhesive strip according to the corresponding curing process to connect the heating component to the heating component patch.

[0018] The above technical solution utilizes the bridging effect of Z-axis conductive adhesive film strips to establish a vertical conductive path at the edge of the repair window, restoring the current path and ensuring normal heating of the repaired area with minimal impact on overall heating uniformity (temperature difference between the repaired area and the surrounding area is less than 10°C). The regular geometric shape of the overlapping interface (such as a circle or rounded rectangle) reduces stress concentration, and combined with the hot-press curing process, the tensile strength of the repaired interface can reach over 10 MPa, meeting the requirements of structural components. This repair method requires no complex equipment, is suitable for rapid on-site repair, and reduces costs.

[0019] Preferably, the planar defect damage area includes a hole defect damage area and a pit defect damage area.

[0020] Preferably, the regular geometric shape is circular, elliptical, or rounded rectangle. A regular shape avoids stress concentration at sharp corners, enhancing the durability of the repaired interface. It is also easy to cut and align, simplifying the repair process and reducing human error.

[0021] Preferably, the first preset width is 3-5 mm, and the preset pressure is 0.3-0.6 MPa. This width and pressure range ensures that the conductive particles fully pierce the insulating matrix to form a reliable Z-axis conductive path, while avoiding excessive material damage. Parametric design ensures the repeatability of the repair results and is suitable for industrial applications.

[0022] Preferably, the heating component patch and the heating layer of the heating component are made of the same material with the same surface resistivity. Materials with the same surface resistivity ensure uniform heating between the repaired area and the surrounding area, preventing localized overheating or cold spots. Material matching improves long-term reliability.

[0023] Preferably, the Z-axis conductive adhesive film strip is an anisotropic conductive material, which is conductive in the thickness direction and insulating in the in-plane direction. The anisotropic characteristic ensures that current flows only vertically, and the in-plane insulation avoids current shunting and concentration, thus mitigating the risk of overheating in the repair area to some extent.

[0024] Secondly, the present invention also provides a method for repairing a composite material heating assembly, comprising the following steps:

[0025] Trim the two ends of the linear crack damage area of ​​the heating component to form a semi-circular hole;

[0026] Along the crack path of the linear crack damage area, trim the burrs and impurities of the heating component;

[0027] The Z-axis conductive adhesive is pre-composite with the conductive fabric, then vacuum pre-pressed and cut into strips with a second preset width.

[0028] Cover the linear cracked area with tape strips, with both ends of the tape strips extending beyond the predetermined length of the linear cracked area.

[0029] Apply a preset contact pressure or apply vacuum pressure to the repair area, and cure the tape strip according to the corresponding curing process to connect the conductive fabric to the heating component.

[0030] In the above technical solution, the semi-circular hole design eliminates stress concentration at the crack tip, preventing crack propagation. By covering the crack with adhesive tape, the conductive path on both sides of the crack is re-established, and the circuit returns to normal after repair. The increased bonding area (e.g., width 3~5mm) improves the bonding strength, and the interlaminar shear strength can reach over 70MPa.

[0031] Preferably, the conductive fabric and the heating layer of the heating component are made of the same material with the same surface resistance. Material consistency ensures resistance matching between the repair area and the substrate, avoiding temperature differences. Using the same material reduces differences in thermal expansion coefficients, improving environmental adaptability.

[0032] Preferably, the Z-axis conductive adhesive is an anisotropic conductive material, which is conductive in the thickness direction and insulating in the in-plane direction. This in-plane insulation prevents current shunting along the crack path, ensuring that the current passes perpendicularly through the repair interface.

[0033] Preferably, the radius of the semicircular hole is 2-3 mm, the second preset width is 3-5 mm, the preset length is 5-10 mm, and the preset contact pressure is 0.3-0.5 MPa.

[0034] (III) Beneficial Effects

[0035] The above-described technical solution of the present invention has at least the following advantages:

[0036] 1. Successful Functional Repair: This invention cleverly re-establishes electrical connections between the old and new heating fabrics or on both sides of the crack by using the "bridging" effect of Z-axis conductive adhesive film strips / Z-axis conductive adhesive, thus restoring the current path. The repaired heating component can be powered on and heated normally, and because the overlap resistance or filling resistance is controllable and extremely small, the impact on the overall heating uniformity is negligible.

[0037] 2. Highly targeted and reliable: Different repair processes were designed for the two main damage forms, planar defects and linear cracks. Planar defect repair ensures strength through regular overlapping interfaces; linear crack repair utilizes crack-stopping semicircles and increased bonding area. Both methods guarantee long-term repair reliability.

[0038] 3. High mechanical strength: By designing an overlap area of ​​3-5mm or grooving to increase the bonding area, and employing a hot-press curing process, the repair interface not only conducts electricity but also possesses extremely high bonding strength. Actual measurements show that the tensile strength of the repaired area for hole repair is greater than or equal to 10MPa, fully meeting the structural requirements for interface strength.

[0039] 4. Avoids local overheating: The use of Z-axis conductive adhesive strips for connection ensures that the current can only pass through the overlap interface or crack section perpendicularly, and will not cause current shunting or concentration in the in-plane direction, which reduces the risk of current density concentration and local overheating caused by the repair process to a certain extent.

[0040] 5. Simple process and low cost: This method requires no complex equipment and has a simple operation process, making it ideal for rapid in-situ repairs. Only a very small area of ​​material needs to be replaced or filled to save the entire large heating component, avoiding total scrap and significantly reducing costs. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic flowchart of the composite material heating component repair method provided in Embodiment 1 of the present invention.

[0043] Figure 2 This is a schematic diagram of the structure of the Z-direction conductive adhesive film strip provided in an embodiment of the present invention.

[0044] Figure 3 This is a schematic flowchart of the composite material heating component repair method provided in Embodiment 2 of the present invention.

[0045] Figure 4 This is a thermal imaging image of the repaired heating component provided in an embodiment of the present invention.

[0046] The labels for the attached figures are as follows:

[0047] 1. Heating component; 2. Heating component patch; 3. Z-direction conductive adhesive strip; 4. Conductive connecting ring; 5. Z-direction conductive adhesive; 6. Conductive fabric; 7. Adhesive strip; 11. Planar defect damage area; 12. Repair window; 13. Electrode; 14. Linear crack damage area; 131. Semicircular hole. Detailed Implementation

[0048] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0049] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0050] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this invention will be described in more detail below with reference to specific embodiments:

[0052] like Figure 1 As shown, this embodiment of the invention provides a method for repairing a composite material heating assembly, including the following steps:

[0053] Completely remove the planar defect damage area 11 of the heating component 1 and trim it to form a repair window 12 with a regular geometric shape;

[0054] Cut a heating component patch 2 that matches the shape of the repair window 12 but is slightly larger in size, and prepare a Z-direction conductive adhesive strip 3 with a first preset width;

[0055] The Z-direction conductive adhesive strip 3 is pasted on the edge of the repair window 12, so that half the width of the Z-direction conductive adhesive strip 3 covers the intact heating component 1 on the edge of the repair window 12, and the other half of the width is suspended above the repair window 12, forming a conductive connecting ring 4.

[0056] Cover the repair window 12 with the heating component patch 2, so that the edge of the heating component patch 2 is completely pressed against the suspended Z-direction conductive adhesive strip 3;

[0057] Apply a preset pressure to the repair area for pre-compression or vacuum pre-compression, and cure the Z-direction conductive adhesive strip 3 according to the corresponding curing process to connect the heating component 1 and the heating component patch 2.

[0058] In one embodiment, the planar defect damage area includes a hole defect damage area and a pit defect damage area.

[0059] In one embodiment, the regular geometry is a circle, an ellipse, or a rounded rectangle.

[0060] In one embodiment, the first preset width is 3~5mm and the preset pressure is 0.3~0.6 MPa.

[0061] In one embodiment, the heating component patch 2 and the heating layer of the heating component 1 are made of the same material with the same surface resistance.

[0062] In one embodiment, the Z-axis conductive adhesive film strip 3 is an anisotropic conductive material, and the Z-axis conductive adhesive film strip 3 is conductive in the thickness direction and insulating in the in-plane direction. For example... Figure 2As shown, the Z-direction conductive adhesive film strip 3 includes an insulating resin matrix 31 and conductive particles 32. The conductive particles 32, with a volume fraction of less than 5%, are dispersed in the insulating resin matrix 31. The nominal diameter D of the conductive particles 32 is greater than the nominal thickness T of the adhesive film before curing, where D ranges from 15 to 120 μm and T ranges from 10 to 100 μm. The ratio D / T of the nominal diameter D of the conductive particles 32 to the nominal thickness T of the adhesive film before curing is 1.1 to 2.0. More preferably, D / T is 1.2 to 1.5. This design ensures that during adhesive film preparation and subsequent lamination, the conductive particles can effectively pierce the adhesive film interface formed by the insulating resin matrix 31, forming physical contact with the upper and lower conductors to be connected, thereby establishing a reliable Z-direction (thickness direction) conductive path, while providing insulation in the in-plane direction.

[0063] like Figure 3 As shown, this embodiment of the invention also provides a method for repairing composite material heating components, including the following steps:

[0064] Cut off both ends of the linear crack damage area 14 of the heating component 1 to form a semi-circular hole 131;

[0065] Along the crack path of the linear crack damage area 14, trim the burrs and impurities of the heating component 1;

[0066] The Z-direction conductive adhesive 5 is pre-composite with the conductive fabric 6, and then vacuum pre-pressed and cut into strips 7 with a second preset width.

[0067] Cover the linear crack damage area 14 with tape strip 7, with both ends of tape strip 7 extending beyond the predetermined length of both ends of the linear crack damage area 14;

[0068] Apply a preset contact pressure or apply vacuum pressure to the repair area, and cure the tape strip according to the corresponding curing process to connect the conductive fabric 6 to the heating component 1.

[0069] In one embodiment, the conductive fabric 6 and the heating layer of the heating component 1 are made of the same material with the same surface resistance.

[0070] In one embodiment, the Z-direction conductive adhesive 5 is an anisotropic conductive material, which is conductive in the thickness direction and insulating in the in-plane direction.

[0071] In one embodiment, the radius of the semicircular hole 131 is 2-3 mm, the second preset width is 3-5 mm, the preset length is 5-10 mm, and the preset contact pressure is 0.3-0.5 MPa.

[0072] The following are specific embodiments provided by the present invention: Embodiment 1: Pore damage to the leading edge heating film of an airfoil

[0073] 1. Situation: During the preparation process, a 10mm×10mm damaged pit (surface defect damage area 11) appeared on the surface of a piece of montmorillonite fabric heating film (heating component 1) used for the leading edge of an airfoil, causing the circuit to be broken.

[0074] 2. Repair process:

[0075] Step 1: Use a circular tool to completely remove the damaged pit, forming a circular repair window 12 with a diameter of 12mm.

[0076] Step 2: Cut a circular heating component patch 2 with a diameter of 15mm from the same sheet resistance. Based on the composite material system it is used in, select a medium-temperature epoxy Z-direction conductive film, and cut the Z-direction conductive film (an epoxy resin film with nickel-plated activated carbon particles as conductive particles) into strips 5mm wide to obtain Z-direction conductive film strips 3.

[0077] Step 3: Attach the Z-axis conductive adhesive strip 3 around the edge of the repair window 12 to form a ring. Then align and cover the circular heating component patch 2, ensuring its edges are completely pressed against the Z-axis conductive adhesive strip 3.

[0078] Step 4: Using a portable hot press with a silicone pad, apply a pressure of 0.5 MPa to the repair area and heat it to 120°C, then keep it warm for 90 minutes to cure.

[0079] 3. Post-repair performance test:

[0080] like Figure 4 As shown, the electrothermal performance is as follows: After being powered on, the entire heating film, including the repair area, can heat up normally. When observed with a thermal imager, the temperature distribution is uniform, and the temperature difference between the repair area and the surrounding area is less than 10°C.

[0081] Mechanical properties: Standard tensile specimens containing the repaired interface were prepared for testing. The failure mode was self-tear of the patch, rather than cracking of the adhesive interface. The tensile strength of the interface was measured to be 20 MPa.

[0082] Durability: After being powered on at 300V for 2 seconds and undergoing 50 heating cycles, its heating performance, resistance value and bonding strength showed no significant changes.

[0083] Example 2: Repair of surface cracks in anti-icing and de-icing heated fabrics

[0084] 1. Situation: A piece of glass fiber-based heating fabric (heating component 1) was bent during transportation, and a linear crack about 30 mm long appeared on the surface (linear crack damage area 14).

[0085] 2. Repair process (using crack repair methods):

[0086] Step 1: Cut semi-circular holes 131 with a radius of 2mm at both ends of the linear crack (linear crack damage area 14).

[0087] Step 2: Cut a 2mm groove along the crack path.

[0088] Step 3: Select a cyanate ester conductive film suitable for its operating environment. Cut the cyanate ester conductive film and the heating fabric with the same sheet resistance as the heating fabric into strips 5mm wide to obtain conductive fabric 6. Composite the conductive film strips with the conductive fabric 6 and compress them under vacuum.

[0089] Step 4: After covering with the polyimide film, cover the area with a flexible heating blanket, apply contact pressure, and cure at 180°C for 90-120 minutes.

[0090] 3. Post-repair performance test:

[0091] Electrothermal performance: After power is applied, the circuit returns to normal. The thermal imager shows that the temperature of the crack repair path is consistent with the surrounding area, with no overheating and a temperature difference of less than 10℃.

[0092] Mechanical properties: interlaminar shear strength, no abnormal deformation or cracking in the repaired area, strong bond between the repair and the matrix, and interlaminar shear strength of the repaired area > 70 MPa.

[0093] Environmental adaptability: The electrical connection is stable after passing the damp heat aging test.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for repairing a composite material heating assembly, characterized in that, Includes the following steps: Completely remove the planar defects and damaged areas of the heating component, and trim them to form a repair window with a regular geometric shape; Cut a heating component patch that matches the shape of the repair window but is slightly larger in size, and prepare a Z-direction conductive adhesive strip with a first preset width; The Z-direction conductive adhesive strip is pasted onto the edge of the repair window, so that half the width of the Z-direction conductive adhesive strip covers the intact heating component at the edge of the repair window, and the other half hangs above the repair window, forming a conductive connection ring. Cover the repair window with the heating component patch, so that the edge of the heating component patch is completely pressed against the suspended Z-axis conductive adhesive strip; Apply a preset pressure to the repair area for pre-compression or vacuum pre-compression, and cure the Z-direction conductive adhesive strip according to the corresponding curing process to connect the heating component to the heating component patch.

2. The method for repairing composite material heating components as described in claim 1, characterized in that, The surface defect damage area includes the hole defect damage area and the pit defect damage area.

3. The method for repairing composite material heating components as described in claim 1, characterized in that, The regular geometric shape is a circle, an ellipse, or a rounded rectangle.

4. The method for repairing composite material heating components as described in claim 1, characterized in that, The first preset width is 3~5mm, and the preset pressure is 0.3~0.6 MPa.

5. The method for repairing composite material heating components as described in claim 1, characterized in that, The heating component patch and the heating layer of the heating component are made of the same material with the same resistivity.

6. The method for repairing composite material heating components as described in claim 1, characterized in that, The Z-direction conductive adhesive film strip is an anisotropic conductive material, and the Z-direction conductive adhesive film strip is conductive in the thickness direction and insulating in the in-plane direction.

7. A method for repairing a composite material heating assembly, characterized in that, Includes the following steps: Trim the two ends of the linear crack damage area of ​​the heating component to form a semi-circular hole; Along the crack path of the linear crack damage area, trim the burrs and impurities of the heating component; The Z-axis conductive adhesive is pre-composite with the conductive fabric, then vacuum pre-pressed and cut into strips with a second preset width. Cover the linear cracked area with tape strips, with both ends of the tape strips extending beyond the predetermined length of the linear cracked area. Apply a preset contact pressure or apply vacuum pressure to the repair area, and cure the tape strip according to the corresponding curing process to connect the conductive fabric to the heating component.

8. The method for repairing composite material heating components as described in claim 7, characterized in that, The conductive fabric and the heating layer of the heating component are made of the same material with the same resistivity.

9. The method for repairing composite material heating components as described in claim 7, characterized in that, The Z-axis conductive adhesive is an anisotropic conductive material, which is conductive in the thickness direction and insulating in the in-plane direction.

10. The method for repairing composite material heating components as described in claim 7, characterized in that, The radius of the semicircular hole is 2-3 mm, the second preset width is 3-5 mm, the preset length is 5-10 mm, and the preset contact pressure is 0.3-0.5 MPa.

Images