Method and system for analyzing compressive strength of composite laminated plate

Abstract

The invention provides a method for analyzing the compression strength of a composite laminated plate, and belongs to the technical field of airplane composite material structural strength analysis, and the method comprises the following steps: obtaining a nondestructive testing image of the composite laminated plate containing impact damage, and extracting a damage area in the nondestructive testing image of the composite laminated plate; based on the geometric distance and the geometric center distance of the damaged area in the nondestructive testing image of the composite laminated plate, the mass center of the damaged area is taken as the center, and the irregular shape of the damaged area is converted into an equivalent ellipse; determining a residual strength expression of the composite material laminated plate containing the elliptical open pores by taking the condition that the average stress of the 0-degree laying layer in the composite material laminated plate reaches the strength limit as a damage judgment condition of the overall failure of the composite material laminated plate; and regarding an equivalent ellipse of an impact damage area in a nondestructive testing image of the composite material laminated plate as an elliptical trepanning damage, and combining with a residual strength expression of the composite material laminated plate to obtain a compressive strength value of the composite material laminated plate after impact.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft composite material structure strength analysis, and in particular, relates to a method and system for analyzing the compression strength of composite laminates. Background Art

[0002] Currently, composite laminates are widely used as load-bearing structures in the aviation field. However, when composite laminate structures are damaged by low-speed impacts such as runway gravel and hail, although it is difficult to observe obvious damage areas on the surface, the mechanical properties are greatly affected. The actual compression strength may drop to 40% or even lower than the undamaged state. Accurately assessing the impact of impact damage on the performance of composite laminate structures plays an important role in the safety of aircraft structures.

[0003] The finite element method can obtain more accurate calculation results, but the finite element method requires the input of the magnitude of the impact energy. In the actual field use environment of the aircraft, the size and speed of the impact object are often not available, that is, the magnitude of the impact energy cannot be obtained. At the same time, the finite element method is highly dependent on the selection of grid density and boundary conditions. The calculation results obtained by different designers vary greatly. There are many restrictions and difficulties in using the finite element method to evaluate the residual strength of composite laminates with impact damage.

[0004] Therefore, in aircraft design, an engineering-usable composite laminate compression strength analysis method is needed for strength calculation. Summary of the invention

[0005] The purpose of the present application is to provide a method and system for analyzing the compressive strength of composite laminates to solve or alleviate at least one problem in the background technology.

[0006] The technical solution of the present application is: a method for analyzing the compressive strength of composite laminates, comprising:

[0007] Acquire a nondestructive testing image of a composite laminate containing impact damage, and extract a damaged area in the nondestructive testing image of the composite laminate;

[0008] Based on the geometric distance and geometric center distance of the damaged area in the nondestructive testing image of the composite laminate, the irregular shape of the damaged area is converted into an equivalent ellipse with the centroid of the damaged area as the center;

[0009] The average stress of the 0° ply in the composite laminate reaches the strength limit as the destruction judgment condition for the overall failure of the composite laminate. The residual strength expression of the composite laminate with elliptical openings is determined. The ellipse equivalent to the impact damage area in the non-destructive testing image of the composite laminate is regarded as an elliptical opening damage. Combined with the residual strength expression of the composite laminate, the compressive strength value of the composite laminate after impact is obtained.

[0010] In a preferred embodiment of the present application, the process of extracting the damaged area in the nondestructive testing image of the composite laminate is:

[0011] The composite material nondestructive testing image is converted into a multi-level grayscale image, the grayscale value of the pixel point in the damaged area is set to a first value, and the grayscale value of the pixel point in the undamaged area is set to a second value, the first value and the second value can make the damaged area and the undamaged area clearly distinguishable, thereby separating the damaged area from the composite material nondestructive testing image.

[0012] In a preferred embodiment of the present application, the equivalent ellipse center coordinates, direction angle, major semi-axis length, and minor semi-axis length satisfy the following:

[0013] The equivalent ellipse center coordinates are

[0014] The direction angle of the major axis of the equivalent ellipse

[0015] Semi-major axis length

[0016] Minor semi-axis length

[0017] Where M pq , μ pq (p,q=0,1,2) are the geometric moment and geometric center distance of the image respectively.

[0018] In a preferred embodiment of the present application, the damage judgment condition expression of the overall failure of the composite laminate is:

[0019]

[0020] Where, l0 is the distance from the edge of the elliptical opening in the 0° ply along the direction perpendicular to the loading direction, and l0 is a characteristic coefficient related only to the material system, which is obtained from engineering experience;

[0021] X C is the ultimate compressive strength of the one-way plate under the material system;

[0022] Stress distribution of 0° ply in composite laminate.

[0023] In a preferred embodiment of the present application, the residual strength expression of the composite laminate containing elliptical openings is:

[0024]

[0025] Where, X is the axial compression failure strength of the single-layer plate;

[0026] Y is the finite plate width correction factor;

[0027] α1, α2, and α3 are laminate constants, respectively, and are defined as follows;

[0028] α1=Q 11 a 11 +Q 12 a 12

[0029] α2=Q 11 a 12 +Q 12 a 22

[0030] α3=Q 11 a 16 +Q 12 a 26

[0031] F1, F2, and F3 are defined as follows;

[0032]

[0033] On the other hand, the technical solution provided by the present application is: a composite material laminate compression strength analysis system, comprising:

[0034] An image extraction module, used to obtain a nondestructive testing image of a composite laminate containing impact damage, and to extract a damaged area in the nondestructive testing image of the composite laminate;

[0035] A loss conversion module, based on the geometric distance and geometric center distance of the damaged area in the nondestructive testing image of the composite laminate, converts the irregular shape of the damaged area into an equivalent ellipse with the centroid of the damaged area as the center;

[0036] The loss processing module takes the average stress of the 0° ply in the composite laminate reaching the strength limit as the destruction judgment condition for the overall failure of the composite laminate, determines the residual strength expression of the composite laminate with an elliptical opening, regards the ellipse equivalent to the impact damage area in the non-destructive testing image of the composite laminate as an elliptical opening damage, and obtains the compressive strength value of the composite laminate after impact in combination with the residual strength expression of the composite laminate.

[0037] In a preferred embodiment of the present application, the process of the image extraction module acquiring and extracting the damaged area in the nondestructive testing image of the composite laminate is as follows:

[0038] The composite material nondestructive testing image is converted into a multi-level grayscale image, the grayscale value of the pixel point in the damaged area is set to a first value, and the grayscale value of the pixel point in the undamaged area is set to a second value, the first value and the second value can make the damaged area and the undamaged area clearly distinguishable, thereby separating the damaged area from the composite material nondestructive testing image.

[0039] In a preferred embodiment of the present application, the equivalent ellipse center coordinates, direction angle, major semi-axis length, and minor semi-axis length satisfy the following:

[0040] The equivalent ellipse center coordinates are

[0041] The direction angle of the major axis of the equivalent ellipse

[0042] Semi-major axis length

[0043] Minor semi-axis length

[0044] Where M pq , μ pq (p,q=0,1,2) are the geometric moment and geometric center distance of the image respectively.

[0045] In a preferred embodiment of the present application, the damage judgment condition expression of the overall failure of the composite laminate is:

[0046]

[0047] Where, l0 is the distance from the edge of the elliptical opening in the 0° ply along the direction perpendicular to the loading direction, and l0 is a characteristic coefficient related only to the material system, which is obtained from engineering experience;

[0048] X C is the axial compression ultimate strength of the one-way plate under the material system;

[0049] Stress distribution of 0° ply in composite laminate.

[0050] In a preferred embodiment of the present application, the residual strength expression of the composite laminate containing elliptical openings is:

[0051]

[0052] Where, X is the axial compression failure strength of the single-layer plate;

[0053] Y is the finite plate width correction factor;

[0054] α1, α2, and α3 are laminate constants, respectively, and are defined as follows;

[0055] α1=Q 11 a 11 +Q 12 a 12

[0056] α2=Q 11 a 12 +Q 12 a 22

[0057] α3=Q 11 a 16 +Q 12 a 26

[0058] F1, F2, and F3 are defined as follows:

[0059]

[0060] In a third aspect, the technical solution provided by the present application is: an electronic device, comprising:

[0061] one or more processors;

[0062] Memory;

[0063] one or more applications stored in the memory and configured to be executed by the one or more processors, the one or more applications configured to:

[0064] Implement the composite material laminate compressive strength analysis method as described in any one of the above.

[0065] In the last aspect, the technical solution provided by the present application is: a computer storage medium, which stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are loaded and executed by the processor to implement the composite laminate compressive strength analysis method as described in any one of the above.

[0066] The method for analyzing the compressive strength of composite laminates provided in the present application is aimed at the problem of evaluating the residual strength of composite laminates containing impact damage, and proposes a method based on non-destructive testing images. The method of the present application does not require knowing the magnitude of the impact energy. The method is efficient and fast in calculation, and can provide accurate data support for aircraft design and maintenance personnel to evaluate the impact damage of composite structures, thereby ensuring the safety of modern aircraft structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0068] Figure 1 Schematic diagram of the compression strength analysis method of the composite laminate of the present application.

[0069] Figure 2 A schematic diagram of an original nondestructive testing image according to an embodiment of the present application.

[0070] Figure 3 This is a schematic diagram of an image of a damaged area after extraction according to an embodiment of the present application.

[0071] Figure 4 This is a schematic diagram of an elliptical hole equivalent in an embodiment of the present application.

[0072] Figure 5 Schematic diagram of the average stress failure criterion model based on 0° ply in this application.

[0073] Figure 6 Schematic diagram of the composite laminate compression strength analysis system for this application

[0074] Figure 7 A schematic diagram of an electronic device of the present application. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0076] In order to overcome the problem in the prior art that the finite element algorithm is cumbersome to calculate and depends on the size of the impact energy, the present application provides a method for analyzing the compressive strength of composite laminates based on impact damage images.

[0077] like Figure 1 As shown, the present application provides a method for analyzing the compressive strength of composite laminates based on impact damage images, comprising:

[0078] Step S100: using a digital image processing method to obtain a nondestructive testing image of a composite laminate containing impact damage, and extracting a damaged area in the nondestructive testing image of the composite laminate.

[0079] The nondestructive testing image is usually a color image. The color nondestructive testing image is converted into a 256-level grayscale image. There is generally a clear boundary between the damaged area and the undamaged area in the grayscale image. The grayscale value of the pixel point in the damaged area is assigned to 255 (white), and the grayscale value of the pixel point in other undamaged areas is assigned to 0 (black). In this way, the damaged area can be separated from the nondestructive testing image. Figure 2 The original NDT images shown and Figure 3 The image of the damaged area after extraction is shown.

[0080] It is understandable that the grayscale value of the pixel point in the defective area in the above embodiment can also be set to 0 (black), while the grayscale value of the pixel point in other undamaged areas can be assigned to 255 (white). In the process of extracting the damaged area, the grayscale value of the pixel point in the defective area can be significantly deviated from the grayscale value of the pixel point in the undamaged area.

[0081] Step S200, based on the geometric distance and geometric center distance of the damaged area in the image, the irregular shape of the damaged area is converted into an equivalent elliptical shape with the centroid of the damaged area as the center.

[0082] The geometric moment M of the damaged area image f(x,y) pq The expression is:

[0083]

[0084] The zero-order moment (M 00 ), first-order moment (M 10 、M 01 ) Determine the centroid coordinates of the damaged area image This centroid is the center of the equivalent ellipse.

[0085] The geometric center moment μ of the damaged area image f(x,y) pq for:

[0086]

[0087] The zero-order central moment (μ 00 ), first-order central moment (μ 11 ) and the second-order central moment (μ 21 , μ 02 ) determine an equivalent ellipse that is inertially equivalent to the damaged area image, wherein the center of the equivalent ellipse coincides with the center of gravity of the damaged area image, and the direction angle θ, the major semi-axis a, and the minor semi-axis b of the equivalent ellipse major axis satisfy:

[0088]

[0089] For example, in this embodiment of the present application, the equivalent ellipse equivalent to the inertia of the damaged area image is determined as follows: Figure 4 As shown, the geometric dimensions of the equivalent ellipse are shown in Table 1:

[0090] Table 1 Geometric dimensions of equivalent ellipse

[0091]

[0092] Step S300, taking the average stress of the 0° ply in the composite laminate reaching the strength limit as the damage judgment condition for the overall failure of the composite laminate, determining the residual strength expression of the composite laminate containing an elliptical opening, and treating the ellipse equivalent to the impact damage area in the non-destructive testing image of the composite laminate as an elliptical opening damage, and combining the residual strength expression of the composite laminate to obtain the compressive strength value of the composite laminate after impact.

[0093] In this application, the process of determining the residual strength expression of a composite laminate containing an elliptical opening is as follows:

[0094] First, the average stress within a certain distance range perpendicular to the loading direction from the edge of the elliptical opening equivalent to the 0° ply of the composite laminate is calculated. When the average stress reaches the compressive strength limit of the unidirectional plate of the material system, the axial load loaded at this time is It is the compressive residual strength of the composite laminate.

[0095] For example, in this embodiment of the present application, it is assumed that a composite laminate with an elliptical opening having a major semicircumference of a and a minor semiaxis of b is subjected to a uniformly distributed axial load at an infinite distance. Distribution, establish a coordinate system with the center of the ellipse, and the major and minor semi-axes are x-axis and y-axis respectively. Under the action of uniformly distributed load, the stress of the internal ply of the composite laminate increases with the increase of load. When the average stress within a certain distance l0 (or characteristic coefficient, characteristic length, which is only related to the material system and obtained from engineering experience) from the edge of the elliptical opening in the 0° ply is equal to the unidirectional plate compressive limit strength X under the material system, the stress in the internal ply increases accordingly. C When , the composite laminate structure is destroyed, that is, the destruction judgment condition expression of the composite laminate overall failure is:

[0096]

[0097] In order to solve the above equation, it is necessary to obtain the stress distribution of the 0° ply of the composite laminate: According to the theory of elastic mechanics, the stress and strain of the plane problem of the composite material plate is solved. The specific process is:

[0098] Assume that there is a thin plate, the external force (including body force) on it is parallel to the plate plane and does not change along the thickness direction. At this time, there are only plane stress and strain. In the plane stress problem, the physical equation of the composite laminate is:

[0099]

[0100] In the formula, ε and γ are strains, σ and τ are stresses, the subscripts x and y are the directions of the coordinate axes, and a ij (i,j=1,2,6) is the material stiffness coefficient, introduce the Elli stress function F(x,y), and assume:

[0101]

[0102] Substituting the above two items into the equilibrium equation, strain coordination equation, and deformation coordination equation of the generalized plane problem of anisotropic elastic body, we can obtain:

[0103]

[0104] Especially for orthotropic composite laminates, when the coordinate axis direction is consistent with the main elastic direction of the material, that is, a 16 =a 26 =0, the above formula can be further simplified as:

[0105]

[0106] By solving the above equations, we can obtain the stress and strain of the composite laminate.

[0107] Then, according to the complex stress function method in elastic mechanics, combined with the formula of the above process, the composite laminate under axial load can be obtained. Macroscopic stress distribution under action:

[0108]

[0109] Where: z j With μ j (=1,2) is the complex parameter in complex variable function theory, z j =x+μ j y;

[0110] μ j is the characteristic equation a 11 μ 4 -2a 16 μ 3 +(2a 12 +a 66 )μ 2 -2a 26 μ+a 22 = complex root of 0;

[0111] According to the physical equation of the composite laminate, the stress of the 0° ply of the composite laminate is:

[0112]

[0113] In the formula, Q ij (i,j=1,2,6) is the stiffness coefficient of the 0° pavement surface, a ij (i,j=1,2,6) is the in-plane stiffness coefficient of the laminate, and the macro stress σ of the composite laminate is x , σ y , τ xy Substituting into the above formula, we can get the stress distribution of the composite laminate at 0°:

[0114] Finally, since the actual structure is not an infinite plate, the finite plate width correction coefficient Y used in elastic mechanics is considered in this application for correction. The finite plate width correction coefficient Y satisfies the following:

[0115]

[0116] Where w is the board width, M and λ are engineering parameters, defined as follows;

[0117]

[0118] Stress distribution of composite laminates at 0° Substituting into the damage judgment condition of overall failure and considering the finite plate width correction factor Y, solve the axial load We can get:

[0119]

[0120] Where, X is the axial compression failure strength of the single-layer plate;

[0121] The coefficients α1, α2, and α3 satisfy:

[0122] α1=Q 11 a 11 +Q 12 a 12 , α2=Q 11 a 12 +Q 12 a 22 , α3=Q 11 a 16 +Q 12 a 26

[0123]

[0124] Finally, the compressive residual strength of the composite laminate was obtained.

[0125] For example, in this embodiment of the present application, the basic mechanical properties of the T800 grade carbon fiber resin-based composite material selected from the composite material are shown in Table 2, where E1, E2, V12, and G12 are the longitudinal modulus, transverse modulus, principal Poisson's ratio, and longitudinal and transverse shear modulus of the unidirectional laminate, respectively, and Xc is the longitudinal compressive strength of the unidirectional laminate;

[0126] Table 2 Basic mechanical properties of composite materials

[0127]

[0128] The laminate layup is [45 / 0 / -45 / 0 / 0 / -45 / 90 / 45 / 90 / 0]s, and the single layer thickness is 0.14mm. The principal axis stiffness matrix of the composite material and the laminate stiffness matrix are obtained.

[0129] The characteristic length l0 is a coefficient value determined based on engineering experience. For example, the compression characteristic length of T800 carbon fiber epoxy resin base is 3.42mm, the compression characteristic length of T700 carbon fiber epoxy resin base is 6.26mm, and the characteristic length of T300 carbon fiber epoxy resin base is 3.09mm. This value is only related to the material system, that is, once the value is determined, it is applicable to the laminate structure of all layers and geometric dimensions of the material system.

[0130] The board width of the composite laminate is 100 mm, and the finite board width correction coefficient Y is calculated to be 0.93.

[0131] Finally, the compressive residual strength of the laminate is calculated according to the calculation formula of the compressive residual strength of the composite laminate.

[0132] By testing the composite laminates with the above parameters, it was found that the compressive residual strength of the composite laminates was 264.30 MPa. Compared with the test results, the compressive residual strength obtained by the method of the present application had a prediction error of 8.9%, and the prediction result was conservative, meeting the requirements for engineering use.

[0133] The method for analyzing the compressive strength of composite laminates provided in the present application is aimed at the problem of evaluating the residual strength of composite laminates containing impact damage, and proposes a method based on non-destructive testing images. The method of the present application does not require knowing the magnitude of the impact energy. The method is efficient and fast in calculation, and can provide accurate data support for aircraft design and maintenance personnel to evaluate the impact damage of composite structures, thereby ensuring the safety of modern aircraft structures.

[0134] On this basis, the present application also provides a composite material laminate compression strength analysis system, the system 10 comprising:

[0135] An image extraction module 11 is used to obtain a nondestructive testing image of a composite laminate containing impact damage, and to extract a damaged area in the nondestructive testing image of the composite laminate;

[0136] A loss conversion module 12, for converting the irregular shape of the damaged area into an equivalent ellipse based on the geometric distance and geometric center distance of the damaged area in the nondestructive testing image of the composite laminate, with the centroid of the damaged area as the center;

[0137] The loss processing module 13 is used to use the average stress of the 0° ply in the composite laminate reaching the strength limit as the damage judgment condition for the overall failure of the composite laminate, determine the residual strength expression of the composite laminate containing an elliptical opening, regard the ellipse equivalent to the impact damage area in the non-destructive testing image of the composite laminate as an elliptical opening damage, and obtain the compressive strength value of the composite laminate after impact in combination with the residual strength expression of the composite laminate.

[0138] like Figure 7 As shown, the electronic device 200 of the embodiment of the present application includes a processor 201, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 202 or the program loaded from the storage device 208 to the random access memory (RAM) 203. The processor 201 may include, for example, a general-purpose microprocessor (such as a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (for example, an application-specific integrated circuit (ASIC)), etc. The processor 201 may also include an onboard memory for caching purposes. The processor 201 may include a single processing unit or multiple processing units for performing different actions of the method flow according to the embodiment of the present disclosure.

[0139] In RAM 203, various programs and data required for the operation of electronic device 200 are stored. Processor 201, ROM 202 and RAM 203 are connected to each other via bus 204. Processor 201 performs various operations of the method flow according to the embodiment of the present disclosure by executing the program in ROM 202 and / or RAM 203. It should be noted that the program can also be stored in one or more memories other than ROM 202 and RAM 203. Processor 201 can also perform various operations of the method or flow according to the embodiment of the application by executing the program stored in the one or more memories.

[0140] According to an embodiment of the present application, the electronic device 200 may further include an input / output (I / O) interface 205, which is also connected to the bus 204. The electronic device 200 may further include one or more of the following components connected to the I / O interface 205: an input device 206 including a keyboard, a mouse, etc.; an output device 207 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage device 208 including a hard disk, etc.; and a communication device 209 including a network interface card such as a LAN card, a modem, etc. The communication device 209 performs communication processing via a network such as the Internet. A drive is also connected to the I / O interface 205 as needed. A removable medium 111, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive as needed so that a computer program read therefrom is installed into the storage device 208 as needed.

[0141] The present application also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, various operations of the above methods or processes according to the embodiments of the present application are implemented.

[0142] According to an embodiment of the present application, the computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, an apparatus or a device. For example, according to an embodiment of the present application, a computer-readable storage medium may include the ROM 202 and / or RAM 203 described above and / or one or more memories other than ROM 202 and RAM 203.

[0143] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for analyzing the compressive strength of composite laminates, characterized in that: include: Acquire a nondestructive testing image of a composite laminate containing impact damage, and extract a damaged area in the nondestructive testing image of the composite laminate; Based on the geometric distance and geometric center distance of the damaged area in the nondestructive testing image of the composite laminate, the irregular shape of the damaged area is converted into an equivalent ellipse with the centroid of the damaged area as the center; The average stress of the 0° ply in the composite laminate reaches the strength limit as the destruction judgment condition for the overall failure of the composite laminate. The residual strength expression of the composite laminate with elliptical openings is determined. The ellipse equivalent to the impact damage area in the non-destructive testing image of the composite laminate is regarded as an elliptical opening damage. Combined with the residual strength expression of the composite laminate, the compressive strength value of the composite laminate after impact is obtained.

2. The method for analyzing the compressive strength of composite laminates according to claim 1, characterized in that: The process of extracting the damaged area in the nondestructive testing image of the composite laminate is as follows: The composite material nondestructive testing image is converted into a multi-level grayscale image, the grayscale value of the pixel point in the damaged area is set to a first value, and the grayscale value of the pixel point in the undamaged area is set to a second value, the first value and the second value can make the damaged area and the undamaged area clearly distinguishable, thereby separating the damaged area from the composite material nondestructive testing image.

3. The method for analyzing the compressive strength of composite laminates according to claim 1, characterized in that: The equivalent ellipse center coordinates, direction angle, major semi-axis length, and minor semi-axis length satisfy the following: The equivalent ellipse center coordinates are The direction angle of the major axis of the equivalent ellipse Major semi-axis length Minor semi-axis length Where M pq , μ pq (p,q=0,1,2) are the geometric moment and geometric center distance of the image respectively.

4. The method for analyzing the compressive strength of composite laminates according to claim 3, characterized in that: The damage judgment condition expression of the overall failure of the composite laminate is: Where, l0 is the distance from the edge of the elliptical opening in the 0° ply along the direction perpendicular to the loading direction, and l0 is a characteristic coefficient related only to the material system, which is obtained from engineering experience; X C is the axial compression ultimate strength of the one-way plate under the material system; Stress distribution of 0° ply in composite laminate.

5. The method for analyzing the compressive strength of composite laminates according to claim 4, characterized in that: The residual strength expression of the composite laminate with elliptical openings is: Where, X is the axial compression failure strength of the single-layer plate; Y is the finite plate width correction factor; α1, α2, and α3 are laminate constants, respectively, and are defined as follows; α1=Q 11 a 11 +Q 12 a 12 α2=Q 11 a 12 +Q 12 a 22 α3=Q 11 a 16 +Q 12 a 26 F1, F2, and F3 are defined as follows:

6. A composite material laminate compression strength analysis system, characterized in that: include: An image extraction module, used to obtain a nondestructive testing image of a composite laminate containing impact damage, and to extract a damaged area in the nondestructive testing image of the composite laminate; A loss conversion module, based on the geometric distance and geometric center distance of the damaged area in the nondestructive testing image of the composite laminate, converts the irregular shape of the damaged area into an equivalent ellipse with the centroid of the damaged area as the center; The loss processing module takes the average stress of the 0° ply in the composite laminate reaching the strength limit as the destruction judgment condition for the overall failure of the composite laminate, determines the residual strength expression of the composite laminate with an elliptical opening, regards the ellipse equivalent to the impact damage area in the non-destructive testing image of the composite laminate as an elliptical opening damage, and obtains the compressive strength value of the composite laminate after impact in combination with the residual strength expression of the composite laminate.

7. The composite material laminate compressive strength analysis system according to claim 1, characterized in that: The process of the image extraction module obtaining and extracting the damaged area in the nondestructive testing image of the composite laminate is as follows: The composite material nondestructive testing image is converted into a multi-level grayscale image, the grayscale value of the pixel point in the damaged area is set to a first value, and the grayscale value of the pixel point in the undamaged area is set to a second value, the first value and the second value can make the damaged area and the undamaged area clearly distinguishable, thereby separating the damaged area from the composite material nondestructive testing image.

8. The composite material laminate compressive strength analysis system according to claim 6, characterized in that: The equivalent ellipse center coordinates, direction angle, major semi-axis length, and minor semi-axis length satisfy the following: The equivalent ellipse center coordinates are The direction angle of the major axis of the equivalent ellipse Major semi-axis length Minor semi-axis length Where M pq , μ pq (p,q=0,1,2) are the geometric moment and geometric center distance of the image respectively.

9. The composite material laminate compressive strength analysis system according to claim 8, characterized in that: The damage judgment condition expression of the overall failure of the composite laminate is: Where, l0 is the distance from the edge of the elliptical opening in the 0° ply along the direction perpendicular to the loading direction, and l0 is a characteristic coefficient related only to the material system, which is obtained from engineering experience; X C is the axial compression ultimate strength of the one-way plate under the material system; Stress distribution of 0° ply in composite laminate.

10. The composite material laminate compressive strength analysis system according to claim 9, characterized in that: The residual strength expression of the composite laminate with elliptical openings is: Where, X is the axial compression failure strength of the single-layer plate; Y is the finite plate width correction factor; α1, α2, and α3 are laminate constants, respectively, and are defined as follows; α1=Q 11 a 11 +Q 12 a 12 α2=Q 11 a 12 +Q 12 a 22 α3=Q 11 a 16 +Q 12 a 26 F1, F2, and F3 are defined as follows:

11. An electronic device, characterized in that: include: one or more processors; Memory; one or more applications stored in the memory and configured to be executed by the one or more processors, the one or more applications configured to: A method for analyzing the compressive strength of composite laminates as claimed in any one of claims 1 to 5 is implemented.

12. A computer storage medium, characterized in that: The computer storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are loaded and executed by the processor to implement the method for compressive strength analysis of composite laminates as described in any one of claims 1 to 5.

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