Method for repairing a curved composite structure, method and device for preparing a negative curvature patch

Abstract

The embodiment of the present disclosure provides a reverse curvature patch preparation method, comprising: fitting a deformable rubber mold on a to-be-repaired curved composite material structure, expanding the surface curvature topography of the to-be-repaired curved composite material structure through mold deformation; fixing the shape of the deformable rubber mold, setting the back surface of the contact surface between the deformable rubber mold and the to-be-repaired curved composite material structure as a working area, laying a plurality of layers of pre-solidified thin patches on the working area opposite the damage area of the to-be-repaired curved composite material structure, and covering a vacuum bag; vacuumizing the vacuum bag through a vacuum device to compress the pre-solidified thin patches; and heating and solidifying the pre-solidified thin patches through a heating device, so as to form a reverse curvature patch of the damage area after solidification. The method effectively reduces the repair cost, improves the repair efficiency, and also guarantees the repair quality. The present disclosure also provides a reverse curvature patch preparation device and a curved composite material structure repair method.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of composite material repair, and particularly relates to a curved composite material structure repair method, a reverse curvature patch preparation method and device. BACKGROUND

[0002] Fiber-reinforced composites have excellent properties such as small specific gravity, large specific modulus and large specific strength, and are widely used in the fields of aerospace, automobiles and the like. Among them, curved areas such as aircraft wings and fuselages have widely used composite materials, which can reduce the weight of the fuselage while bearing the load.

[0003] The curved composite material structure at the position of the aircraft fuselage and the like often suffers from lightning strikes or impact damage during actual flight, thereby generating damage and further leading to structural failure. Therefore, in the battlefield or other special environments, the curved composite material structure of the aircraft needs to be quickly repaired. However, the traditional repair method has the following problems: the damaged curved composite material is placed in a hot press tank for repair, which has high time and money costs and cannot meet the requirements of battlefield quick repair. The wet-lay repair method fixes a sheet metal back plate as a mold inside the damaged area, and completes the repair by curing and forming on the mold. This repair method needs to prepare a sheet metal back plate, has high cost, and the preparation process of the curved structure sheet metal back plate is complex and time-consuming.

[0004] With the rapid development of composite materials, the current quick repair of curved structures usually adopts a pre-cured patch directly bonded repair technology. However, when the damage size expands to a certain extent, the time required for quickly forming a composite patch under complex curvature is too long, which is a major difficulty in the development of repair technology. In addition, due to the problem of excessive residual stress after repairing the complex curvature structure, secondary damage such as delamination and debonding often occurs. SUMMARY

[0005] In view of the above problems, the present application provides a curved composite material structure repair method, a reverse curvature patch preparation method and device to solve the problems of high repair cost and long repair time in the prior art.

[0006] The first aspect of this disclosure provides a method for preparing a reverse curvature patch, comprising: attaching a deformable rubber mold to a composite material structure of a surface to be repaired, and using the mold to deform and trace the surface curvature morphology of the composite material structure to be repaired; fixing the shape of the deformable rubber mold, setting the back side of the contact surface between the deformable rubber mold and the composite material structure to be repaired as the working area, laying multiple layers of pre-cured thin patches in the working area at a position opposite to the damaged area of ​​the composite material structure to be repaired, and covering them with a vacuum bag; evacuating the vacuum bag using a vacuum device to press the pre-cured thin patches tightly; and pressing and heating the pre-cured thin patches using a heating device to cure them, thereby forming a reverse curvature patch for the damaged area after curing.

[0007] Optionally, the step of attaching the deformable rubber mold to the composite material structure to be repaired and using the mold to deform and trace the surface curvature morphology of the composite material structure to be repaired includes: attaching the deformable rubber mold to the composite material structure to be repaired; evacuating the inside of the rubber skin to shrink and adhere the rubber skin to the filling particles to fix its shape, and tracing the surface curvature morphology of the composite material structure to be repaired.

[0008] Optionally, the method further includes: before covering the vacuum bag, sequentially laying an isolation film, a heating blanket, and a breathable felt on the pre-cured thin patch; wherein the heating blanket is used as the heating device to press and heat the pre-cured thin patch to cure it.

[0009] The second aspect of this disclosure provides an apparatus for preparing a reverse curvature patch, applied to the reverse curvature patch preparation method as described in any one of the first aspects. The deformable rubber mold is used to adhere to the composite material structure to be repaired, and the surface curvature morphology of the composite material structure to be repaired is traced by mold deformation. A pre-cured thin patch is used, after the deformable rubber mold has been fixed in shape, with the back side of the contact surface between the deformable rubber mold and the composite material structure to be repaired as the working area, and laid out at a position opposite to the damaged area of ​​the composite material structure to be repaired in this working area. After vacuum compression and heat treatment, a reverse curvature patch for the damaged area is formed. A vacuum device is used to cover the pre-cured thin patch with a vacuum bag, then evacuate the vacuum bag to press the pre-cured thin patch tightly. A heating device is used to press and heat the pre-cured thin patch to cure it.

[0010] Optionally, the deformable rubber mold includes: a rubber skin and filler particles, wherein the filler particles are located in the rubber skin; wherein the filler particles are fixed in shape by evacuating the interior of the rubber skin.

[0011] Optionally, the pre-cured thin patch is a semi-cured continuous fiber-reinforced composite sheet prepreg.

[0012] Optionally, the thickness of the continuous fiber reinforced composite sheet prepreg is 0.2 to 0.3 mm.

[0013] Optionally, the heating device includes a heating blanket, a thermocouple, and a temperature controller.

[0014] A third aspect of this disclosure provides a method for repairing a curved composite material structure, comprising: preparing an inverse curvature patch, wherein the inverse curvature patch has the opposite curvature to the damaged area of ​​the curved composite material structure to be repaired; and bonding the inverse curvature patch to the damaged area.

[0015] Optionally, the radius of curvature of the composite material structure to be repaired should be no less than 50 mm.

[0016] The above-described at least one technical solution adopted in the embodiments of this disclosure can achieve the following beneficial effects:

[0017] Based on this, the present invention proposes a method for preparing a reverse curvature patch repair structure for curved composite material structures. Compared with traditional repair methods, it does not require the manufacture of new sheet metal back plate tooling or autoclave molding, effectively reducing repair costs and improving repair efficiency. Furthermore, the use of reverse curvature patches reduces the residual stress of the structure after bonding, which can greatly reduce repair time while ensuring repair quality. Attached Figure Description

[0018] To gain a more complete understanding of this disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 The flowchart illustrating a method for preparing a reverse curvature patch according to an embodiment of the present disclosure is shown in the schematic diagram.

[0020] Figure 2 The illustration shows a schematic diagram of a method for preparing a reverse curvature patch according to an embodiment of the present disclosure;

[0021] Figure 3 The illustration schematically shows another method for preparing a reverse curvature patch according to an embodiment of the present disclosure;

[0022] Figure 4 The flowchart illustrating a method for repairing a curved composite material structure provided in an embodiment of this disclosure is shown schematically.

[0023] Figure label:

[0024] 1-Deformable rubber mold with the curvature morphology of the composite material structure under traced surface; 2-Working area; 3-Pre-cured thin patch; 4-Isolation film; 5-Heating blanket; 6-Breathable felt; 7-Vacuum bag; 8-Damaged composite material structure; 9-Damaged area; 10-Reverse curvature patch. Detailed Implementation

[0025] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0026] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0027] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0028] In one embodiment of this disclosure, an apparatus for preparing a reverse curvature patch is provided, comprising: a deformable rubber mold, a pre-cured thin patch, a vacuum device, and a heating device.

[0029] Deformable rubber molds are used to adhere to the composite material structure to be repaired, and the surface curvature morphology of the composite material structure to be repaired is obtained by deforming the mold.

[0030] Precursed thin patches are used when a deformable rubber mold is fixed in shape. The back side of the contact surface between the deformable rubber mold and the composite material structure to be repaired is used as the working area. The patch is laid in the working area at the position opposite to the damaged area of ​​the composite material structure to be repaired. After vacuum compression and heat treatment, a patch with reverse curvature of the damaged area is formed.

[0031] Vacuum equipment is used to cover pre-cured thin patches in vacuum bags, then evacuate the vacuum bags to press the pre-cured thin patches tightly.

[0032] Heating equipment is used to press and heat the pre-cured thin patch for curing.

[0033] The reverse curvature patch preparation apparatus can be applied to a reverse curvature patch preparation method provided in the embodiments of this disclosure.

[0034] Figure 1 The flowchart illustrating a method for preparing a reverse curvature patch according to an embodiment of the present disclosure is shown schematically.

[0035] like Figure 1 As shown in the embodiments of this disclosure, a method for preparing a reverse curvature patch includes steps S110 to S140.

[0036] S110 involves attaching a deformable rubber mold to the composite material structure to be repaired, and then using the mold to deform and transfer the surface curvature morphology of the composite material structure to be repaired.

[0037] The deformable rubber mold 1 has deformability and can deform according to the curved contour of the structure. In one embodiment of this disclosure, the deformable rubber mold includes a rubber skin and filler particles, with the filler particles located in the rubber skin. By evacuating the interior of the rubber skin, the filler particles can be fixed in shape.

[0038] In this embodiment, a deformable rubber mold is attached to the composite material structure to be repaired; then, a vacuum is drawn inside the rubber skin, causing the rubber skin to shrink and adhere tightly to the filling particles to fix its shape, thereby mapping the surface curvature morphology of the composite material structure to be repaired.

[0039] Optionally, in some embodiments, the deformable rubber mold can be replaced with a malleable material. The malleable material can be in liquid, solid, or other forms and can be fixed in shape under specific conditions.

[0040] S120, fix the shape of the deformable rubber mold, set the back of the contact surface between the deformable rubber mold and the composite material structure to be repaired as the working area, lay multiple layers of pre-cured thin patches in the working area opposite to the damaged area of ​​the composite material structure to be repaired, and cover them with a vacuum bag.

[0041] The pre-cured thin patch is a semi-cured continuous fiber reinforced composite prepreg with a thickness of 0.2 to 0.3 mm.

[0042] In this embodiment, before covering the pre-cured thin patch with a vacuum bag, a release film, a heating blanket, and a breathable felt are sequentially laid on the pre-cured thin patch; wherein, the heating blanket is used as a heating device to press and heat the pre-cured thin patch to cure it.

[0043] S130 uses a vacuum device to evacuate the vacuum bag and press the pre-cured thin patch tightly.

[0044] S140 uses a heating device to press and heat the pre-cured thin patch to cure it, forming a reverse curvature patch in the damaged area after curing.

[0045] In this embodiment, the heating device may include a heating blanket, a thermocouple, and a temperature controller. The heating blanket is used to heat the pre-cured thin patch, the thermocouple is used to detect the temperature generated by the heating blanket and transmit the generated electrical signal to the temperature controller, and the temperature controller is used to control the temperature of the heating blanket.

[0046] The method for preparing the inverse curvature patch provided in this disclosure will be further illustrated below through two embodiments.

[0047] Example 1

[0048] In this embodiment, crack damage in an epoxy resin-based carbon fiber reinforced composite material structure with convex curvature is repaired by patching. Figure 2 A schematic diagram illustrating the fabrication of the inverse curvature patch of this embodiment is shown.

[0049] Combination Figure 2 As shown, the repair of cracks and damage in epoxy resin-based carbon fiber reinforced composite structures with convex curvature includes the following steps.

[0050] The first step is to determine the damage area and extent of the curved composite material structure as a crack with a length of 20 mm and a curvature radius of approximately 200 mm.

[0051] The second step involves first removing the protective paint from the repair area of ​​the curved composite material structure, then sanding the repair area with sandpaper, cleaning it with solvent, and finally drying it with a hot air gun.

[0052] The third step involves attaching a deformable rubber mold to the curved composite material structure to be repaired. The rubber mold deforms according to the curved contour of the structure. Vacuuming the mold causes the rubber surface to shrink and adhere tightly to the filler particles, thus maintaining a fixed shape. The surface curvature morphology of the curved composite material structure is then mapped using the mold deformation.

[0053] The fourth step is to remove the rubber mold after it has been shaped and place it on the workbench. Set the side of the rubber mold with the opposite curvature to the curved composite material structure as the working area. Lay out multiple layers of pre-cured thin patches in this working area, and then lay out the outer surface with an isolation film, heating blanket, and breathable felt. Cover it with a vacuum bag and then vacuum it.

[0054] The fifth step involves curing in a heat-curing instrument at a pressure of 0.1 MPa and a temperature of 130 degrees Celsius for 2 hours. This process allows for rapid, precise, and high-quality repairs in a single step.

[0055] Step 6: Remove the isolation membrane, heating blanket, breathable felt, and vacuum bag, and take out the inverse curvature patch to complete the preparation.

[0056] Example 2

[0057] In this embodiment, cracks and damage to an epoxy resin-based carbon fiber reinforced composite material structure with concave curvature are repaired by patching. Figure 3 A schematic diagram illustrating the fabrication of the inverse curvature patch of this embodiment is shown.

[0058] Combination Figure 3 As shown, the repair of cracks and damage in epoxy resin-based carbon fiber reinforced composite structures with concave curvature includes the following steps.

[0059] The first step is to determine the damage area and extent of the curved composite material structure as a crack with a length of 10 mm and a curvature radius of approximately 150 mm.

[0060] The second step involves first removing the protective paint from the repair area of ​​the curved composite material structure, then sanding the repair area with sandpaper, cleaning it with solvent, and finally drying it with a hot air gun.

[0061] The third step involves attaching a deformable rubber mold to the curved composite material structure to be repaired. The rubber mold deforms according to the curved contour of the structure. Vacuuming the mold causes the rubber surface to shrink and adhere tightly to the filler particles, thus maintaining a fixed shape. The surface curvature morphology of the curved composite material structure is then mapped using the mold deformation.

[0062] The fourth step is to remove the rubber mold after it has been shaped and place it on the workbench. Set the side of the rubber mold with the opposite curvature to the curved composite material structure as the working area. Lay out multiple layers of pre-cured thin patches in this working area, and then lay out the outer surface with an isolation film, heating blanket, and breathable felt. Cover it with a vacuum bag and then vacuum it.

[0063] The fifth step involves curing in a heat-curing instrument at a pressure of 0.1 MPa and a temperature of 130 degrees Celsius for 2 hours. This process allows for rapid, precise, and high-quality repairs in a single step.

[0064] Step 6: Remove the isolation membrane, heating blanket, breathable felt, and vacuum bag, and take out the inverse curvature patch to complete the preparation.

[0065] Compared with traditional repair methods, the reverse curvature patch preparation method disclosed herein does not require the fabrication of new sheet metal backplate tooling or autoclave molding, effectively reducing repair costs and improving repair efficiency.

[0066] Based on such Figure 1The reverse curvature patch prepared by the method shown in this disclosure, in another aspect, provides a method for repairing curved composite material structures.

[0067] Figure 4 The flowchart illustrating a method for repairing a curved composite material structure provided in an embodiment of this disclosure is shown schematically.

[0068] like Figure 4 As shown in the embodiments of this disclosure, a method for repairing curved composite material structures includes steps S410 to S420.

[0069] S410, prepare an inverse curvature patch, the curvature of which is opposite to that of the damaged area of ​​the composite material structure to be repaired.

[0070] S420, the inverse curvature patch is bonded to the damaged area.

[0071] There is a certain tension between the patch and the curved surface structure. If the curvature of the patch matches the curvature of the surface structure, a large tension will be generated, leading to greater residual stress and potentially subsequent failure. Conversely, if the curvature of the patch is opposite to that of the surface structure, the tension between the patch and the surface structure will be smaller, resulting in less residual stress. In this embodiment, using a patch with reverse curvature can reduce the residual stress in the bonded structure and ensure repair quality.

[0072] It should be noted that in some application scenarios, such as the rapid repair of curved composite material structures on aircraft, the radius of curvature of the surface of the composite material structure to be repaired should not be less than 50mm.

[0073] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0074] Although this disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made to this disclosure without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents.

Claims

1. A method for repairing curved composite material structures, characterized in that, include: Prepare an inverse curvature patch, wherein the curvature of the inverse curvature patch is opposite to that of the damaged area of ​​the composite material structure to be repaired; The inverse curvature patch is bonded to the damaged area.

2. The method according to claim 1, characterized in that, The radius of curvature of the composite material structure to be repaired should be no less than 50 mm.

3. The method according to claim 1, characterized in that, The preparation of the reverse curvature patch includes: A deformable rubber mold is attached to the composite material structure to be repaired, and the surface curvature morphology of the composite material structure to be repaired is traced by the deformation of the mold. The shape of the deformable rubber mold is fixed, and the back side of the contact surface between the deformable rubber mold and the composite material structure to be repaired is set as the working area. Multiple layers of pre-cured thin patches are laid in the working area at the position opposite to the damaged area of ​​the composite material structure to be repaired, and then covered with a vacuum bag. The vacuum bag is evacuated using a vacuum device to press the pre-cured thin patch tightly. The pre-cured thin patch is pressed and heated to cure using a heating device, and after curing, a reverse curvature patch is formed in the damaged area.

4. The method according to claim 3, characterized in that, The process of attaching a deformable rubber mold to the composite material structure to be repaired, and using the mold deformation to trace the surface curvature morphology of the composite material structure to be repaired, includes: A deformable rubber mold is attached to the composite material structure of the curved surface to be repaired. The deformable rubber mold includes a rubber skin and filler particles, with the filler particles located in the rubber skin. The inside of the rubber mold is evacuated, causing the rubber mold to shrink and adhere to the filling particles to fix its shape, and the surface curvature morphology of the composite material structure to be repaired is then traced.

5. The method according to claim 3, characterized in that, The method further includes: Before covering the vacuum bag, a release film, a heating blanket, and a breathable felt are laid sequentially on the pre-cured thin patch; The heating blanket is used as the heating device to press and heat the pre-cured thin patch to cure it.

6. The method according to claim 3, characterized in that, The pre-cured thin patch is a semi-cured continuous fiber-reinforced composite sheet prepreg.

7. The method according to claim 6, characterized in that, The thickness of the continuous fiber reinforced composite prepreg sheet is 0.2~0.3 mm.

8. The method according to claim 3, characterized in that, The heating equipment includes a heating blanket, a thermocouple, and a temperature controller.

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