Composite material repair method and repair structure

Abstract

This invention provides a method and structure for repairing composite materials, including grinding a damaged area on the composite material to remove the damaged original fiber layer and form a repair area; the exposed cross-sections of multiple original fiber layers at the edge of the repair area form an overlap area; laying a first fiber repair layer in the repair area and the overlap area, such that both ends of the first fiber repair layer extend obliquely upwards to the topmost original fiber layer in the overlap area and overlap with the topmost original fiber layer; sequentially laying multiple fiber repair layers on the first fiber repair layer until the number of fiber repair layers laid is the same as the number of original fiber layers ground off; applying an adhesive layer to the topmost fiber repair layer and the topmost original fiber layer; laying a protective layer on the adhesive layer, covering the fiber repair layer and the original fiber layer; and placing the repaired composite material in an autoclave for curing. This method solves the problems of complex processes and low efficiency in existing repair methods.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a method and structure for repairing composite materials. Background Technology

[0002] Composite materials are widely used in modern aircraft design due to their high strength and lightweight properties. However, damage is inevitable during long-term use. Since composite materials are mainly composed of fibers and resin matrices, which are significantly different from metal materials, repairing composite materials is a major challenge.

[0003] Currently, the method for repairing damaged composite materials involves removing the damaged fiber layers and then laying new fiber layers layer by layer in the areas where the damaged fiber layers were removed. Each fiber layer overlaps with the corresponding fiber layer on the composite material body. This repair method is extremely complex and cumbersome because each fiber layer needs to overlap with the corresponding fiber structure layer on the composite material body. It has low repair efficiency, and the overlapping surfaces of the lower layers are covered by the overlapping surfaces of the upper layers, making it difficult to install and inspect each overlapping surface, i.e., the repair area. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a composite material repair method and repair structure to solve the problems of complex processes and low efficiency in the existing repair methods.

[0005] To achieve the above and other related objectives, a first aspect of the present invention provides a method for repairing composite materials, comprising the following steps:

[0006] S1. The damaged area on the composite material is polished to remove the damaged original fiber layer, thereby forming a repair area. The cross-section of the multiple original fiber layers exposed at the edge of the repair area forms an overlap area.

[0007] S2. Lay a first fiber repair layer brushed with resin in the repair area and the overlapping area. The laying of the first fiber repair layer specifically includes first applying a first adhesive layer to the repair area and the overlapping area, and then laying the first fiber repair layer on the first adhesive layer, such that the two ends of the first fiber repair layer extend upward at an angle to the original fiber layer at the top of the overlapping area and overlap on the original fiber layer at the top.

[0008] S3. Lay multiple layers of fiber repair layers brushed with resin on the first fiber repair layer in sequence until the number of fiber repair layers laid is the same as the number of original fiber layers that have been polished away. The method of laying each fiber repair layer is the same as the method of laying the first fiber repair layer in step S2.

[0009] S4. Apply an adhesive layer to the topmost fiber repair layer and the topmost original fiber layer, and lay a protective layer on the adhesive layer, the protective layer covering the fiber repair layer and the original fiber layer.

[0010] S5. Place the repaired composite material from step 4 into an autoclave for curing, so that the laid multi-layer fiber repair layer and protective layer are cured.

[0011] Furthermore, in step 2, before laying the first fiber repair layer on the first adhesive layer, a first strain sensor is also provided on the first adhesive layer.

[0012] Furthermore, in step S4, before laying the protective layer on the adhesive layer, a second strain sensor is also provided on the adhesive layer, and the second strain sensor is located between the topmost fiber repair layer and the protective layer.

[0013] Furthermore, the adhesive surface layer is made of epoxy resin.

[0014] Furthermore, the protective layer is made of the same material as the fiber repair layer.

[0015] As described above, the composite material repair method of the present invention has the following beneficial effects: The method only requires overlapping the bottommost fiber repair layer with the topmost original fiber layer on the composite material body, and then sequentially bonding fiber repair layers onto the bottommost fiber repair layer. Compared with the prior art, which requires each newly laid fiber layer to overlap with the corresponding original fiber layer on the composite material body, this greatly simplifies the repair process and reduces its difficulty, thus significantly improving the repair efficiency of composite materials. Simultaneously, the use of a first strain sensor and a second strain sensor enables real-time safety performance monitoring of the repaired area, greatly improving the reliability of the composite material during use. This method is particularly significant and valuable for repairing composite materials used in aircraft.

[0016] A second aspect of the present invention provides a composite material repair structure made by the above-described composite material repair method. The composite material repair structure includes a composite material body, a repair area on the composite material body, multiple fiber repair layers on the repair area, and a first strain sensor between the lowest fiber repair layer and the composite material body.

[0017] Furthermore, a protective layer is provided on the topmost fiber repair layer, and one end of the protective layer extends to the composite material body. A second strain sensor is provided between the protective layer and the topmost fiber repair layer.

[0018] The beneficial effects of the composite material repair structure of the present invention are the same as those of the above-mentioned composite material repair method, so they will not be repeated here. Attached Figure Description

[0019] Figure 1 The diagram shows a process schematic of the composite material repair method provided by the present invention.

[0020] Figure 2 The diagram shown is a schematic representation of the repair structure of the composite material provided by the present invention.

[0021] Explanation of reference numerals in the attached figures

[0022] 10 Composite Material Body

[0023] 11. Primitive fibrous layer

[0024] 20 Fiber Repair Layer

[0025] 21 First strain sensor

[0026] 22 Second strain sensor

[0027] 23 Protective Layer Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] In the description of this invention, it should be noted that, unless otherwise specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., used to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to 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 invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Please see Figure 1 and Figure 2 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0032] This invention provides a method for repairing composite materials, the composite material comprising an original fiber layer and a resin matrix, and the repair method specifically includes the following steps:

[0033] S1. The damaged area on the composite material is polished to remove the damaged original fiber layer, thereby forming a repair area. The cross-section of the multiple original fiber layers exposed at the edge of the repair area forms an overlap area.

[0034] Specifically, before grinding the damaged area on the composite material, you can first confirm the specific location and area of ​​the damage, and then mark the area to be ground with a marker. When grinding, you can use a mini grinder to grind the marked damaged area, i.e. the damaged original fiber layer, layer by layer.

[0035] For ease of description and expression, let's define the fiber layer of the composite material itself as the original fiber layer 11. It can be understood that after the damaged original fiber layer 11 on the composite material is polished, a low-lying repair area will be formed. The cross-section of the multiple original fiber layers exposed at the edge of the low-lying repair area is the overlap area, which has a certain angle, i.e., a chamfered angle.

[0036] Specifically, to ensure the repair effect, when grinding the damaged area on the composite material, the bevel angle of the repair area formed by grinding needs to be determined according to the strength of the composite material. Specifically, the cross-section of the multiple original fiber layers, i.e., the overlap area, forms the hypotenuse of a right-angled triangle. The thickness of the original fiber layer ground off is defined as one vertical right-angled side (i.e., the thickness of the overlap area in the vertical direction), and the projection of the overlap area in the horizontal direction is defined as the horizontal right-angled side (i.e., the width of the overlap area). When the composite material contains medium-strength fibers, the optimal ratio of the vertical thickness to the width of the overlap area is 1:30. When the composite material contains high-strength fibers, the optimal ratio is 1:40.

[0037] Specifically, in this embodiment, the original fiber layer of the composite material is carbon fiber or glass fiber, and the resin matrix is ​​epoxy resin.

[0038] S2. Lay a first fiber repair layer brushed with resin in the repair area and the overlapping area. The laying of the first fiber repair layer specifically includes first applying a first adhesive layer to the repair area and the overlapping area, and then laying the first fiber repair layer on the first adhesive layer, such that the two ends of the first fiber repair layer extend upward at an angle to the original fiber layer at the top of the overlapping area and overlap on the original fiber layer at the top.

[0039] Specifically, such as Figure 1 As shown in the figure (only one end of the overlap diagram is shown), it can be understood that in this step S2, when the first fiber repair layer, i.e. the lowest fiber repair layer 20, is laid in the repair area, both ends of the lowest fiber repair layer 20 extend upwards at an angle to the top of the original fiber layer 11 in the overlap area and overlap with the top of the original fiber layer 11. This ensures that the end of the lowest fiber repair layer 20 is connected to the cross-section of the multiple original fiber layers exposed at the edge of the repair area, and then the end overlaps with the top of the original fiber layer.

[0040] Specifically, in this embodiment, the material of the first adhesive layer is epoxy resin, and the material of the fiber repair layer 20 is the same as that of the original fiber layer 11 of the composite material. Specifically, in this step S2, the first fiber repair layer brushed with resin can be understood as a wet fiber repair layer with resin brushed on its surface, and the resin is specifically epoxy resin.

[0041] Furthermore, during use, in order to conveniently and in real-time perform safety checks on the performance of the repaired area, such as... Figure 2As shown, in step S2, before laying the first fiber repair layer on the first adhesive layer, a first strain sensor 21 is also installed on the first adhesive layer, specifically between the first fiber repair layer (the bottommost fiber repair layer 20) and the original fiber layer 11. Thus, during use, the first strain sensor 21 can detect the stress changes of the fiber repair layer in the repaired area under stress in real time, and transmit this stress change information to an external monitoring system. This allows for mechanical property analysis of the repaired area to determine if the fiber repair layer has failed. If failure is detected, the external monitoring system will issue an alarm signal, enabling real-time safety monitoring of the repaired area.

[0042] S3. Lay multiple layers of fiber repair layers brushed with resin on the first fiber repair layer in sequence until the number of fiber repair layers laid is the same as the number of original fiber layers that have been polished away. The method of laying each fiber repair layer is the same as the method of laying the first fiber repair layer in step S2.

[0043] S4. Apply an adhesive layer to the topmost fiber repair layer and the topmost original fiber layer, and lay a protective layer on the adhesive layer, the protective layer covering the fiber repair layer and the original fiber layer.

[0044] Specifically, in this embodiment, the material of the coated adhesive layer is epoxy resin.

[0045] Furthermore, during use, in order to perform real-time safety monitoring of the performance of the protective layer 23, such as... Figure 2 As shown, in step S4, before laying the protective layer 23 on the adhesive layer, a second strain sensor 22 is installed on the adhesive layer, positioned between the top fiber repair layer 20 and the protective layer 23. Thus, during use, the second strain sensor 22 can detect stress changes in the protective layer under stress in real time and transmit this stress change information to an external monitoring system. This allows for mechanical performance analysis of the protective layer to determine if it has failed. If failure is detected, the external monitoring system will issue an alarm signal, achieving real-time safety monitoring of the protective layer. Alternatively, in actual use, the stress change information detected by the first strain sensor 21 and the second strain sensor 22 can be analyzed collaboratively to determine the safety performance of the repaired area, resulting in more accurate safety performance detection.

[0046] Specifically, in this embodiment, the material of the protective layer can be the same as or different from the material of the fiber repair layer.

[0047] S5. Place the repaired composite material from step 4 into an autoclave for curing, so that the laid multi-layer fiber repair layer and protective layer are cured.

[0048] As can be seen from the above, the composite material repair method of the present invention only requires overlapping the bottommost fiber repair layer with the topmost original fiber layer on the composite material body, and then sequentially bonding fiber repair layers onto the bottommost fiber repair layer. Compared with the prior art, which requires each newly laid fiber layer to overlap with the corresponding original fiber layer on the composite material body, this greatly simplifies the repair process and reduces the difficulty of the repair process, thus significantly improving the repair efficiency of composite materials. Simultaneously, the use of the first and second strain sensors enables real-time monitoring of the safety performance of the repaired area, greatly improving the reliability of the composite material during use. This invention's composite material repair method is of significant importance and value, especially for repairing composite materials used in aircraft.

[0049] Another aspect of the present invention provides a composite material repair structure made by the above-described composite material repair method, such as... Figure 2 As shown, the composite material repair structure includes a composite material body 10, a repair area on the composite material body 10, and multiple fiber repair layers 20 on the repair area. A first strain sensor 21 is provided between the bottom fiber repair layer 20 and the composite material body 10.

[0050] To further improve the service life and strength of the composite material repair structure, preferably, a protective layer 23 is provided on the top fiber repair layer 20, and one end of the protective layer 23 extends to the composite material body 10, and a second strain sensor 22 is provided between the protective layer 23 and the top fiber repair layer 20.

[0051] The beneficial effects of the composite material repair structure of the present invention are the same as those of the above-mentioned composite material repair method, so they will not be repeated here.

[0052] In summary, the composite material repair method of this invention can significantly improve the repair efficiency of composite materials and enables real-time safety performance monitoring of the repaired area. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0053] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for repairing composite materials, wherein the composite material comprises an original fiber layer and a resin matrix, characterized in that, Includes the following steps: S1. The damaged area on the composite material is polished to remove the damaged original fiber layer, thereby forming a repair area. The cross-section of the multiple original fiber layers exposed at the edge of the repair area forms an overlap area. S2. Lay a first fiber repair layer brushed with resin in the repair area and the overlapping area. The laying of the first fiber repair layer specifically includes first applying a first adhesive layer to the repair area and the overlapping area, and then laying the first fiber repair layer on the first adhesive layer, such that the two ends of the first fiber repair layer extend upward at an angle to the original fiber layer at the top of the overlapping area and overlap on the original fiber layer at the top. S3. Lay multiple layers of fiber repair layers brushed with resin on the first fiber repair layer in sequence until the number of fiber repair layers laid is the same as the number of original fiber layers that have been polished away. The method of laying each fiber repair layer is the same as the method of laying the first fiber repair layer in step S2. S4. Apply an adhesive layer to the topmost fiber repair layer and the topmost original fiber layer, and lay a protective layer on the adhesive layer, the protective layer covering the fiber repair layer and the original fiber layer. S5. Place the repaired composite material from step 4 into an autoclave for curing, so that the laid multi-layer fiber repair layer and protective layer are cured.

2. The composite material repair method according to claim 1, characterized in that, In step 2, before laying the first fiber repair layer on the first adhesive layer, a first strain sensor is also provided on the first adhesive layer.

3. The composite material repair method according to claim 1, characterized in that, In step S4, before laying the protective layer on the adhesive layer, a second strain sensor is also provided on the adhesive layer, and the second strain sensor is located between the top fiber repair layer and the protective layer.

4. The composite material repair method according to claim 1, characterized in that, The adhesive surface layer is made of epoxy resin.

5. A method for repairing composite materials according to claim 1, characterized in that, The protective layer is made of the same material as the fiber repair layer.

6. A composite material repair structure manufactured using the composite material repair method according to any one of claims 1 to 5, characterized in that, The composite material repair structure includes a composite material body, a repair area on the composite material body, multiple fiber repair layers on the repair area, and a first strain sensor between the bottommost fiber repair layer and the composite material body.

7. A composite material repair structure according to claim 6, characterized in that, A protective layer is provided on the topmost fiber repair layer, and one end of the protective layer extends to the composite material body. A second strain sensor is provided between the protective layer and the topmost fiber repair layer.

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