Method of adhesive repair of primary load bearing laminate

Abstract

This invention discloses a method for adhesive repair of a main load-bearing laminate, comprising: performing an engineering analysis of the stress form of the area to be repaired in the main load-bearing laminate to determine the stress form of the area to be repaired; formulating a repair plan for the area to be repaired based on the repair area and the determined stress form; determining the repair method of the repair plan based on the stress form of the area to be repaired; analyzing the scope of application of the repair method of the repair plan to obtain the scope of application analysis results; and determining a repair method that meets the stress requirements of the main load-bearing laminate based on the stress characteristics of the main load-bearing laminate and the scope of application analysis results. This invention can determine an optimal repair plan for the main load-bearing plate of a composite material, thereby effectively reducing the structural weight.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of structural strength technology, and in particular to a method for adhesive repair of a main load-bearing laminate. Background Technology

[0002] Adhesive bonding repair is a common repair method in composite material load-bearing laminate structures. The repair process typically involves two methods: patching and excavation. Currently, there is no definitive repair solution tailored to different structures to determine which repair method best affects the overall structural stress distribution. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for adhesive bonding repair of a main load-bearing laminate, which can determine an optimal repair scheme for the main load-bearing plate of the composite material, thereby effectively reducing the structural weight.

[0004] This invention provides a method for adhesive repair of a main load-bearing laminate, comprising:

[0005] An engineering analysis of the stress form of the area to be repaired in the main load-bearing laminate is performed to determine the stress form of the area to be repaired.

[0006] Based on the repair area of ​​the main load-bearing laminate and the determined stress form, a repair plan is formulated for the area to be repaired;

[0007] Based on the stress pattern of the area to be repaired, determine the repair method of the repair scheme;

[0008] The scope of application of the repair method in the repair plan is analyzed, and the results of the scope of application analysis are obtained;

[0009] Based on the stress characteristics of the main load-bearing laminate and the analysis results of its application scope, a repair method that meets the stress requirements of the main load-bearing laminate is determined.

[0010] Optionally, in the adhesive repair method for the main load-bearing laminate as described above, the stress form of the area to be repaired includes: tensile stress, compressive stress, shear stress, and bending stress, as well as combined stress, wherein the combined stress includes at least two of the above-mentioned stresses.

[0011] Optionally, in the adhesive repair method for the main load-bearing laminate described above, the repair scheme includes: patch repair and excavation repair. The patch repair method includes patch patch repair and overlapping patch repair, and the excavation repair method includes patch excavation repair and overlapping excavation repair.

[0012] Optionally, the adhesive repair method for the main load-bearing laminate described above further includes:

[0013] A three-dimensional progressive damage strength analysis was performed on the repair method that met the stress requirements of the main load-bearing laminate, and the results of the three-dimensional progressive damage strength analysis were obtained.

[0014] Optionally, in the adhesive repair method for the main load-bearing laminate described above, the stiffness degradation mode of the damage variable in the three-dimensional progressive damage strength analysis adopts a linear piecewise degradation mode.

[0015] Optionally, in the adhesive repair method for the main load-bearing laminate described above, the step of performing a three-dimensional progressive damage strength analysis on the determined repair method that meets the stress requirements of the main load-bearing laminate includes:

[0016] In the process of conducting three-dimensional progressive damage strength analysis on the repair methods that meet the stress requirements of the main load-bearing laminate, the Hasing failure criterion is used as the strength failure criterion.

[0017] Optionally, in the adhesive repair method for the main load-bearing laminate described above, the strength failure criteria include: fiber failure in three orthogonal directions, matrix failure, and delamination failure.

[0018] Optionally, the adhesive repair method for the main load-bearing laminate described above further includes:

[0019] The damage failure mode and failure bearing capacity of the three-dimensional progressive damage intensity analysis results are analyzed to obtain the damage failure mode and failure bearing capacity of the area to be repaired.

[0020] Optionally, the adhesive repair method for the main load-bearing laminate described above further includes:

[0021] Based on the comparison between the destructive bearing capacity of the area to be repaired and the design bearing capacity of the main load-bearing laminate, the structural parameters of the area to be repaired are optimized; wherein, the optimization of the structural parameters of the area to be repaired includes: when the destructive bearing capacity of the area to be repaired is greater than the design bearing capacity of the main load-bearing laminate, the area to be repaired is subjected to ply weight reduction treatment; when the destructive bearing capacity of the area to be repaired is less than the design bearing capacity of the main load-bearing laminate, the area to be repaired is subjected to ply weight increase treatment;

[0022] The steps of performing three-dimensional progressive damage strength analysis on the area to be repaired after ply weight reduction or ply weight increase are repeated until the damage failure mode and failure bearing capacity of the three-dimensional progressive damage strength analysis results are analyzed, until the failure bearing capacity of the area to be repaired is equal to the design bearing capacity of the main load-bearing laminate.

[0023] The adhesive repair method for the main load-bearing laminate provided in this invention compares and analyzes patch patching repair, lap patching repair, patch excavation repair, and lap excavation repair, giving the advantages and disadvantages of each scheme, thus providing a better repair scheme. Furthermore, the optimal structural scheme is subjected to three-dimensional asymptotic damage failure mode and failure load strength evaluation analysis, and finally the optimal structural parameters are obtained, such as the failure bearing capacity of the area to be repaired being equal to the design bearing capacity of the main load-bearing laminate. Attached Figure Description

[0024] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0025] Figure 1 A flowchart illustrating a method for adhesive repair of a main load-bearing laminate, provided as an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a patch repair procedure according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of another patch repair method in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of an overlapping patching repair in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of another overlapping patching repair method in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of a patch repair procedure according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of another patch repair method in an embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram of an overlapping patch repair method according to an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of another overlapping patching repair method in an embodiment of the present invention;

[0034] Figure 10 A flowchart illustrating another adhesive repair method for a main load-bearing laminate provided in an embodiment of the present invention;

[0035] Figure 11 This is a schematic diagram illustrating a method for setting damage variables in an embodiment of the present invention;

[0036] Figure 12This is a schematic diagram of a composite material reinforced laminate structure for a certain type of aircraft.

[0037] Figure 13 To Figure 12 The diagram shows a three-dimensional asymptotic damage analysis of a patch repair structure of a composite material reinforced laminate. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0039] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they may not be described again in some embodiments.

[0040] Figure 1 This is a flowchart illustrating a method for adhesive repair of a primary load-bearing laminate, provided as an embodiment of the present invention. The adhesive repair method for the primary load-bearing laminate provided in this embodiment may include the following steps:

[0041] S110, Perform an engineering analysis of the stress form of the area to be repaired in the main load-bearing laminate to determine the stress form of the area to be repaired;

[0042] S120, Based on the repair area of ​​the main load-bearing laminate and the determined stress form, formulate a repair plan for the area to be repaired;

[0043] S130, Based on the stress pattern of the area to be repaired, determine the repair method of the repair plan;

[0044] S140, Analyze the scope of application of the repair methods in the repair plan, and obtain the scope of application analysis results;

[0045] S150, based on the analysis results of the stress characteristics and application range of the main load-bearing laminate, a repair method that meets the stress requirements of the main load-bearing laminate is determined.

[0046] The adhesive repair method for the main load-bearing laminate provided in this embodiment of the invention provides the advantages and disadvantages of various repair schemes for the main load-bearing laminate structure of composite materials, and gives a better repair scheme.

[0047] In this embodiment of the invention, the stress form of the area to be repaired may include: tensile stress, compressive stress, shear stress, and bending stress, as well as combined stress, wherein the combined stress includes at least two of the above-mentioned stresses.

[0048] Optionally, the repair scheme in this embodiment of the invention may include: patch repair and excavation repair. Specifically, the patch repair method includes: patch patch repair and overlapping patch repair, and the excavation repair method includes: patch excavation repair and overlapping excavation repair.

[0049] (1) Patch patch repair: The advantage is that the patch is easy to make and simple to construct. The disadvantage is that the peeling stress at the edge of the patch is high and it has a certain impact on the aerodynamic shape. It is a permanent repair method for composite material structures with small loads and relatively thin structures.

[0050] Figure 2 This is a schematic diagram of a patch repair procedure according to an embodiment of the present invention. Figure 3 This is a schematic diagram of another patch repair method in an embodiment of the present invention. Figure 2 The image shows a single-sided patch application and repair. Figure 3 The image shows a double-sided patch application and repair.

[0051] (2) Overlap patch repair: Asymmetrical patches cause load eccentricity, resulting in high peel stress in the adhesive layer at the edge of the patch. This method is often used to repair locations with limited access space.

[0052] Figure 4 This is a schematic diagram of an overlapping patch repair method according to an embodiment of the present invention. Figure 5 This is a schematic diagram of another overlapping patching repair method in an embodiment of the present invention. Figure 4 The diagram illustrates the overlapping and patching repair of a single-sided patch. Figure 5 The diagram illustrates the overlapping and patching repair of double-sided patches.

[0053] (3) Patch repair: This method is a repair method that maintains the original structural shape. The shear stress distribution on the adhesive surface is relatively uniform, and it is mostly used in thicker composite laminate structures.

[0054] Figure 6 This is a schematic diagram of a patch repair procedure according to an embodiment of the present invention. Figure 7 This is a schematic diagram of another patch repair method in an embodiment of the present invention. Figure 6 The diagram illustrates the sloped excavation and repair method. Figure 7 The diagram illustrates a stepped patching and repair method.

[0055] (4) Overlapping patch repair: The composite material patch is filled between two mother plates to ensure that the thickness of the repair area is close to the thickness of the original structure, rather than completely exceeding the surface of the mother plate. This can ensure the shape of the structure and is suitable for forms with smaller stress.

[0056] Figure 8 This is a schematic diagram of an overlapping patch repair method according to an embodiment of the present invention. Figure 9This is a schematic diagram of another overlapping patching repair method in an embodiment of the present invention. Figure 8 This illustrates a sloped, overlapping patching repair method. Figure 9 The diagram illustrates a stepped overlapping patching repair.

[0057] Optionally, Figure 10 A flowchart illustrating another adhesive repair method for a primary load-bearing laminate provided in an embodiment of the present invention. Figure 1 Based on the process shown, the method provided in this embodiment of the invention may further include:

[0058] S160, a three-dimensional progressive damage strength analysis is performed on the repair method that meets the stress requirements of the main load-bearing laminate, and the results of the three-dimensional progressive damage strength analysis are obtained.

[0059] In the three-dimensional progressive damage strength analysis of this invention, the stiffness degradation method of the damage variable adopts a linear piecewise degradation method.

[0060] Optionally, the implementation of S160 in this embodiment of the invention may include:

[0061] In the process of conducting three-dimensional progressive damage strength analysis on the repair methods that meet the stress requirements of the main load-bearing laminate, the Hasin failure criterion is used as the strength failure criterion.

[0062] The strength failure criteria in the embodiments of the present invention may include: fiber failure in three orthogonal directions, matrix failure, and delamination failure.

[0063] Optionally, the method provided in the embodiments of the present invention may further include:

[0064] S170, the damage failure mode and failure bearing capacity of the three-dimensional progressive damage intensity analysis results are analyzed to obtain the damage failure mode and failure bearing capacity of the area to be repaired.

[0065] Optionally, the method provided in the embodiments of the present invention may further include:

[0066] S180, Based on the comparison between the failure bearing capacity of the area to be repaired and the design bearing capacity of the main load-bearing laminate, the structural parameters of the area to be repaired are optimized; wherein, the implementation method of optimizing the structural parameters of the area to be repaired may include: when the failure bearing capacity of the area to be repaired is greater than the design bearing capacity of the main load-bearing laminate, the area to be repaired is subjected to ply weight reduction treatment; when the failure bearing capacity of the area to be repaired is less than the design bearing capacity of the main load-bearing laminate, the area to be repaired is subjected to ply weight increase treatment.

[0067] S190: Repeat steps S160 to S170 for the area to be repaired after ply weight reduction or ply weight increase treatment until the failure bearing capacity of the area to be repaired is equal to the design bearing capacity of the main load-bearing laminate.

[0068] Optionally, in S180 of this embodiment of the invention,

[0069] The adhesive repair method for the main load-bearing laminate provided in this invention compares and analyzes patch patching repair, lap patching repair, patch excavation repair, and lap excavation repair, giving the advantages and disadvantages of each scheme, thus providing a better repair scheme. Furthermore, the optimal structural scheme is subjected to three-dimensional asymptotic damage failure mode and failure load strength evaluation analysis, and finally the optimal structural parameters are obtained, such as the failure bearing capacity of the area to be repaired being equal to the design bearing capacity of the main load-bearing laminate.

[0070] The following detailed implementation example illustrates the method for adhesive repair of the main load-bearing laminate provided in this invention. The adhesive repair method for the main load-bearing laminate may specifically include the following steps:

[0071] Step 1: Conduct an engineering analysis of the stress forms (tension, compression, shear, and bending) of the main load-bearing composite laminate repair structure to understand the basic stress forms of the structure.

[0072] Step 2, for the shelf repair area, provides different repair solutions: patch patching repair, overlap patching repair, patch excavation repair, and overlap excavation repair, for a total of four repair solutions. The repair methods are as follows: Figures 2 to 9 As shown;

[0073] Step 3: Determine the application scope of different repair schemes based on the stress form: The advantages, disadvantages and application scope of patch patching repair, overlap patching repair, patch excavation repair and overlap excavation repair have been described in detail in the above embodiments, so they will not be repeated here.

[0074] Step 4: Based on the advantages, disadvantages and application scope of the above repair schemes, a repair scheme for the main load-bearing laminate structure of composite material structure is given: patch excavation and repair. This scheme can effectively meet the structural stress requirements and is suitable for composite laminate structures with large load-bearing forms.

[0075] Step 5: Perform three-dimensional asymptotic damage analysis on the patch repair scheme, using the Hasion failure criterion. The failure criteria are set as: fiber failure in three orthogonal directions, matrix failure, and delamination failure. The stiffness degradation mode of the damage variable is a linear piecewise function, such as... Figure 11 The diagram shown is a schematic diagram of a method for setting damage variables in an embodiment of the present invention.

[0076] Step 6: Through progressive damage numerical calculation and analysis of the patch repair scheme, it was found that the damage mode of the laminate in the repair area is the crushing of the matrix and fibers in the repair area, and the crushing of the repair adhesive hole to the upper and lower edges of the laminate leads to the final failure of the laminate.

[0077] The method provided in this invention is applicable to adhesive repair of composite material main structures. This method has significant application value and has been verified in a certain type of concentrated load-bearing structure. For example... Figure 12 The diagram shows a composite material reinforced layer structure of a certain type of machine. The structure is subjected to a large load, and the composite skin is damaged. Four repair methods are used for repair. A comparison of the four structural schemes shows that the patch repair method effectively reduces structural stress and reduces structural weight by 17%.

[0078] A three-dimensional asymptotic damage analysis was performed on the patch repair structure, revealing the damage status of each layer of the laminate in the repair area. The damage mode was fiber compression failure, with the compression point along the repair corner. Furthermore, the numerically calculated residual compressive strength of the laminate showed good agreement with experimental results. Figure 13 As shown, this is for Figure 12 The diagram shows a three-dimensional asymptotic damage analysis of a patch repair structure of a composite material reinforced laminate.

[0079] While the embodiments disclosed in this invention are as described above, they are merely illustrative of the embodiments to facilitate understanding of the invention and are not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for adhesive bonding repair of a main load-bearing laminate, characterized in that, include: An engineering analysis of the stress form of the area to be repaired in the main load-bearing laminate is performed to determine the stress form of the area to be repaired. Based on the repair area of ​​the main load-bearing laminate and the determined stress form, a repair plan is formulated for the area to be repaired; the repair plan includes patch repair and excavation repair, the patch repair method includes patch patch repair and overlapping patch repair, and the excavation repair method includes patch excavation repair and overlapping excavation repair. Based on the stress pattern of the area to be repaired, determine the repair method of the repair scheme; The scope of application of the repair method in the repair plan is analyzed, and the results of the scope of application analysis are obtained; Based on the stress characteristics of the main load-bearing laminate and the analysis results of its application scope, a repair method that meets the stress requirements of the main load-bearing laminate is determined. A three-dimensional progressive damage strength analysis was performed on the repair method that met the stress requirements of the main load-bearing laminate, and the results of the three-dimensional progressive damage strength analysis were obtained. The damage failure mode and failure bearing capacity of the three-dimensional progressive damage intensity analysis results are analyzed to obtain the damage failure mode and failure bearing capacity of the area to be repaired. Based on the comparison between the destructive bearing capacity of the area to be repaired and the design bearing capacity of the main load-bearing laminate, the structural parameters of the area to be repaired are optimized; wherein, the optimization of the structural parameters of the area to be repaired includes: when the destructive bearing capacity of the area to be repaired is greater than the design bearing capacity of the main load-bearing laminate, the area to be repaired is subjected to ply weight reduction treatment; when the destructive bearing capacity of the area to be repaired is less than the design bearing capacity of the main load-bearing laminate, the area to be repaired is subjected to ply weight increase treatment; The steps of performing three-dimensional progressive damage strength analysis on the area to be repaired after ply weight reduction or ply weight increase are repeated until the damage failure mode and failure bearing capacity of the three-dimensional progressive damage strength analysis results are analyzed, until the failure bearing capacity of the area to be repaired is equal to the design bearing capacity of the main load-bearing laminate.

2. The adhesive bonding repair method for the main load-bearing laminate according to claim 1, characterized in that, The stress forms of the area to be repaired include: tensile stress, compressive stress, shear stress, and bending stress, as well as combined stress, wherein the combined stress includes at least two of the above-mentioned stresses.

3. The adhesive repair method for the main load-bearing laminate according to claim 1, characterized in that, In the three-dimensional progressive damage strength analysis, the stiffness degradation of the damage variable adopts a linear piecewise degradation method.

4. The adhesive repair method for the main load-bearing laminate according to claim 3, characterized in that, The three-dimensional progressive damage strength analysis of the repair method that meets the stress requirements of the main load-bearing laminate includes: In the process of conducting three-dimensional progressive damage strength analysis on the repair methods that meet the stress requirements of the main load-bearing laminate, the Hasing failure criterion is used as the strength failure criterion.

5. The adhesive repair method for the main load-bearing laminate according to claim 4, characterized in that, The strength failure criteria include: fiber failure in three orthogonal directions, matrix failure, and delamination failure.

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