Thermosetting composite material laminated board and layering repairing method thereof

Abstract

The invention provides a thermosetting composite material laminated board and a layering repairing method thereof. The layering repairing method comprises the following steps: calibrating the position and depth of a defect area; drilling a glue filling hole with the depth exceeding the layering depth; a body resin layer which is in a solid state at normal temperature and has air permeability is placed on the glue filling hole; laying an adhesive-tight isolating layer on the resin layer, sealing the resin in the defect area, and manufacturing a vacuum bag on the surface of the product; vacuumizing at normal temperature in an autoclave, heating to melt the resin into low-viscosity liquid, pressurizing to extrude and permeate the resin into a lamination defect gap, and finishing lamination defect repair after the resin is cured. Compared with an existing repairing method, the repairing method has the advantages that damage to products is small, professional equipment for repairing is not needed, the technology is simple, cost is low, the application range is wide, layering defects at any position can be repaired, pressurizing seepage force in the vacuum state is high, and the repairing effect on tiny layering gaps is good.

Description

Technical Field

[0001] The invention relates to the technical field of composite material repair technology, in particular to a thermosetting composite material laminate and a layered repair method thereof. Background Art

[0002] Thermosetting composite laminates are widely used in various high-performance structures and functional components in aviation and aerospace. Thermosetting composite laminates, especially complex structures or large components, are prone to local delamination defects after curing due to improper local paving or uneven pressurization during the molding process. Delamination defects affect the performance of the product and may cause significant losses such as product degradation or scrapping. Therefore, the repair of delamination defects in thermosetting composite laminates has high economic value.

[0003] The repair methods available in existing materials mainly include the patching method and the edge injection method, both of which require professional equipment and high requirements for operating skills. Improper repair will cause structural damage. The repair limitations are large and it is difficult to apply it to local repairs of complex structures.

[0004] Patent document CN104827738A (application number: 201510176041.0) discloses a composite laminate repair method. The composite laminate repair method comprises the following steps: step 1: preparing a mixed repair material having the same stiffness as the position to be repaired of the composite laminate; step 2: repairing the position to be repaired by using the mixed repair material. Summary of the invention

[0005] In view of the defects in the prior art, an object of the present invention is to provide a thermosetting composite laminate and a layered repair method thereof.

[0006] A delamination repair method for a thermosetting composite laminate provided by the present invention comprises:

[0007] Step S1: calibrate the layer position and depth of the defect area;

[0008] Step S2: making a glue filling hole in the layered area;

[0009] Step S3: Laying a resin layer on the glue filling hole;

[0010] Step S4: laying an isolation auxiliary layer on the resin layer;

[0011] Step S5: making a vacuum bag on the surface of the composite material covering the delamination area;

[0012] Step S6: vacuum exhaust at room temperature;

[0013] Step S7: heating to melt and liquefy the resin;

[0014] Step S8: applying pressure to infiltrate resin into the layer gaps;

[0015] Step S9: demoulding and trimming after curing, and non-destructive testing.

[0016] Preferably, the glue filling holes are blind holes with a depth exceeding the delamination depth, a hole diameter of φ1mm to φ3mm, and a spacing of 10 to 30mm.

[0017] Preferably, the method further comprises: grinding and roughening the sidewalls of the glue filling hole to expose the gaps in the delamination area.

[0018] Preferably, the step S3 comprises: laying a body resin layer which is solid at room temperature and has air permeability on the glue filling hole, a hardened felt or a hard glue film with air passages which is used to absorb the body glue.

[0019] Preferably, the step S4 comprises: laying an isolation auxiliary layer on the resin layer, which is one or a combination of an adhesive-impermeable isolation film, a breathable release cloth, and a breathable felt, to seal the resin in the defective area.

[0020] Preferably, the step S6 comprises: evacuating the autoclave at room temperature, wherein the degree of vacuum of the evacuated air at room temperature is better than -0.095 MPa.

[0021] Preferably, step S7 comprises: heating the resin to melt it into a low-viscosity liquid, and the temperature of heating the molten liquefied resin is a temperature at which the viscosity of the melted resin is ≤0.3 Pa.S.

[0022] Preferably, the step S8 comprises: applying pressure of 0.1-1.5 MPa to penetrate the resin into the layer gap.

[0023] Preferably, the step S8 comprises: the pressurizing method for infiltrating the resin into the layered gaps is autoclave pressurization or mechanical pressurization.

[0024] A thermosetting composite laminate provided by the present invention is repaired by using the above-mentioned layered repair method for thermosetting composite laminates.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention adopts a repair method of drilling glue holes to penetrate glue into the gaps of layered defects, which greatly reduces the impact of repair on product structure performance and appearance compared with the digging and patching method;

[0027] 2. The present invention adopts a hardened felt or a mesh or corrugated hard film with air passages that is solid at room temperature and breathable at high temperature, which replaces the complicated process of vacuum introduction of liquid resin, greatly simplifies the operation and reduces the cost;

[0028] 3. The present invention adopts a combination of room temperature vacuuming, non-adhesive isolation film assistance and high temperature pressurization to achieve high-pressure glue injection for layering of non-edge areas under vacuum. Compared with the existing edge glue injection repair method, it greatly reduces the repair cost and increases the scope of application.

[0029] 4. The present invention has little damage to the product, does not require professional repair equipment, has a simple process, low cost, and a wide range of applications. It can repair delamination defects at any position. It has strong pressurized penetration in a vacuum state and has a good repair effect on tiny delamination gaps.

[0030] 5. The present invention provides a method for repairing delamination of thermosetting composite laminates, which is suitable for repairing complex structures or large or small thermosetting composite laminates with local delamination defects after molding, thereby solving the problem that local delamination defects of thermosetting composite laminates are difficult to repair after molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0032] Figure 1 The figure is a process flow chart of an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of auxiliary material laying according to an embodiment of the present invention.

[0034] In the figure, 201 is a composite laminate, 202 is a delamination defect, 203 is a glue filling hole, 204 is a hardened felt saturated with bulk resin, 205 is an adhesive-proof release cloth, 206 is a breathable release cloth, and 207 is a vacuum bag. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0036] Example 1

[0037] The present invention aims at solving the problem that complex or large-scale thermosetting composite laminates have local delamination after molding, which affects product performance and causes great economic losses, and there is no effective repair method. A method for repairing delamination of thermosetting composite laminates is proposed, which solves the problem that local delamination defects of thermosetting composite laminates are difficult to repair after molding.

[0038] The delamination repair method of the thermosetting composite laminate is as follows: Figure 1 As shown, the method includes the following main steps:

[0039] Step 1: Determine the layer position and depth;

[0040] Step 2: Making glue filling holes in the delamination area;

[0041] Step 3: Lay a resin layer on the glue filling hole;

[0042] Step 4: Laying an isolation auxiliary layer on the resin layer;

[0043] Step 5: Making a vacuum bag on the composite surface outside the delamination area;

[0044] Step 6: Vacuum exhaust at room temperature;

[0045] Step 7: Heating to melt and liquefy the resin;

[0046] Step 8: Apply pressure to infiltrate the resin into the layered gaps;

[0047] Step 9: After curing, demoulding and trimming are performed without destructive testing.

[0048] Specifically, the blind holes with a depth of the glue filling holes exceeding the delamination depth have a hole diameter of φ1mm to φ3mm and a spacing of 10 to 30mm.

[0049] Specifically, the sidewalls of the glue filling hole are polished, roughened and cleaned to expose the gaps in the delamination area.

[0050] Specifically, the resin layer laid on the glue filling hole is a hardened felt saturated with the main glue or a mesh or corrugated hard glue film with air passages.

[0051] Specifically, the isolation auxiliary layer laid on the resin layer is one or a combination of a non-adhesive isolation film, a breathable release cloth, and a breathable felt.

[0052] Specifically, the vacuum degree of the room temperature vacuum exhaust is better than -0.095MPa.

[0053] Specifically, the temperature of the heated melted liquefied resin is a temperature at which the viscosity of the melted resin is ≤0.3 Pa.S.

[0054] Specifically, the pressure for pressurizing the resin to penetrate into the layer gap is 0.1-1.5 MPa.

[0055] Specifically, the pressurization method for infiltrating the resin into the layered gaps is autoclave pressurization or mechanical pressurization.

[0056] A thermosetting composite laminate provided by the present invention is repaired by using the above-mentioned layered repair method for thermosetting composite laminates.

[0057] The present invention provides a method for repairing delamination of thermosetting composite laminates, which is suitable for repairing local delamination defects of thermosetting composite laminates with complex structures or large or small structures after molding, and solves the problem that local delamination defects of thermosetting composite laminates are difficult to repair after molding.

[0058] Example 2

[0059] Embodiment 2 is a preferred embodiment of Embodiment 1

[0060] like Figure 2 As shown, this embodiment further describes the method for repairing the delamination of a thermosetting composite laminate; the outer contour is φ2000mm×1000mm, and it is a supporting structure of a T800 / epoxy resin composite laminate 201 structure, and there is a delamination defect 202 at the lower flange. The flange wall thickness is 8mm, the defect size is 30mm×70mm, the depth is 2mm from the surface, and it is located at the connection position between the R angle and the flange. The specific process method for repairing the delamination defect 202 is as follows.

[0061] According to the production process documents, ultrasonic nondestructive testing is performed on the flange defect position according to GJB1038.1A, and the defect range and depth are marked. Then, a φ1.5mm drill bit with diamond grit on the surface is used within the flange defect marking range, and a 15mm×15mm interval is used to drill a glue repair hole 203 with a depth of 5 to 6mm. After drilling, compressed air and anhydrous acetone are used to clean the hole to fully expose the layered gap. A hardened felt 204 with a thickness of 1 to 3mm and saturated with the main body resin is placed on the glue repair hole. The hardened felt 204 saturated with the main body resin is laid 10 to 20mm larger than the single side of the defect. Then, a layer of non-adhesive release cloth 205 and a layer of breathable release cloth 206 are placed on the glue layer in sequence, and the non-adhesive release cloth 205 covers the hardened felt 204 saturated with the main body resin. Finally, a vacuum bag 207 is prepared for the repair area on the carbon fiber surface. Put the product into the autoclave and connect a thermocouple to control the temperature. Evacuate the product to a vacuum better than -0.095MPa at room temperature, maintain the vacuum for ≥15min, then heat it to 120±10℃ and keep it warm for 20min to turn the resin into a low-viscosity liquid resin. Then press the autoclave to 0.3Mpa and keep it warm for 1h to infiltrate the low-viscosity liquid resin wrapped in an impermeable isolation film into the gap of the layered defects. Then stop vacuuming, heat it to 150℃ and keep it warm for 3h, then cool it down to room temperature and demould it. After the lower flange is repaired, ultrasonic non-destructive testing is performed again. The results show that the defective area meets the A-level requirements of GJB2895.

[0062] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for repairing delamination of a thermosetting composite laminate, characterized in that: include: Step S1: calibrate the layer position and depth of the defect area; Step S2: making a glue filling hole in the layered area; Step S3: Laying a resin layer on the glue filling hole; Step S4: laying an isolation auxiliary layer on the resin layer; Step S5: making a vacuum bag on the surface of the composite material covering the delamination area; Step S6: vacuum exhaust at room temperature; Step S7: heating to melt and liquefy the resin; Step S8: applying pressure to infiltrate resin into the layer gaps; Step S9: demoulding and trimming after curing, and non-destructive testing.

2. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The glue filling holes are blind holes with a depth exceeding the layering depth, a hole diameter of φ1mm to φ3mm, and a spacing of 10 to 30mm.

3. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The method further comprises: grinding and roughening the side wall of the glue filling hole to make it clear and expose the gap in the delamination area.

4. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The step S3 comprises: laying a solid body resin layer with air permeability at room temperature on the glue filling hole, and a hardened felt or a hard glue film with air passages for absorbing the body glue.

5. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The step S4 comprises: laying an isolation auxiliary layer on the resin layer, which is one or a combination of an adhesive-proof isolation film, a breathable release cloth, and a breathable felt, and sealing the resin in the defective area.

6. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The step S6 comprises: evacuating the autoclave at room temperature, wherein the degree of vacuum of the evacuated air at room temperature is better than -0.095 MPa.

7. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The step S7 includes: heating the resin to melt it into a low-viscosity liquid, and the temperature of heating the molten liquefied resin is a temperature that makes the viscosity of the melted resin ≤0.3 Pa.S.

8. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The step S8 includes: applying pressure of 0.1-1.5 MPa to infiltrate the resin into the layer gap.

9. The method for repairing delamination of thermosetting composite laminate according to claim 1, characterized in that: The step S8 includes: the pressurization method of infiltrating the resin into the layered gaps is autoclave pressurization or mechanical pressurization.

10. A thermosetting composite laminate, characterized in that: The thermosetting composite laminate is repaired by using the layered repair method of any one of claims 1 to 9.

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