A composite laminated sheet interlaminar damage identification and failure determination method, device, equipment and medium

Abstract

The present application relates to the field of nondestructive testing, and provides a composite laminated sheet interlaminar damage identification and failure determination method, comprising: collecting acoustic emission signals of a composite laminated sheet in a short beam shear test, and extracting amplitude intensity and peak frequency; classifying and identifying damage categories in an interlaminar shear failure process; calculating a relative cumulative count of acoustic emission signals of each damage, and synchronously calculating a load change increment, and constructing a relationship curve of both and time; determining a damage starting time according to an initial change feature point of the relationship curve relative to the cumulative count curve, and cooperatively determining an interlaminar shear failure point in combination with a mutation feature of the load increment curve, and outputting a failure point load value as a limit load of interlaminar shear strength. The present application also provides a device, equipment and medium applying the method. The present application effectively identifies damage modes and determines an interlaminar shear failure starting point, and accurately determines a shear strength of a laminated sheet.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a method, apparatus, equipment and medium for identifying interlaminar damage and determining failure in composite laminated thin plates. Background Technology

[0002] Fiber-reinforced resin matrix composite laminates are widely used in aerospace, automotive, and wind power industries due to their excellent specific strength, specific stiffness, and designability. However, the fiber-resin interface is a weak link in composite laminates. The interlaminar properties of composite laminates are a key factor directly affecting their service performance, and interlaminar shear strength is also an important indicator for evaluating the performance of composite laminates. The standard test method for evaluating the interlaminar shear strength of composite laminates generally adopts the short beam shear test. In the test, the general criterion for determining interlaminar failure of the specimen is: when the load-displacement curve reaches its peak (ultimate load), the load value drops by more than 30%. However, when using this method to test thin composite plates, typical load-displacement curve characteristics do not appear, making it difficult to determine interlaminar failure of the composite thin plate and to determine the ultimate strength for calculating the interlaminar shear strength. Relying solely on macroscopic load-displacement curves and final cross-sectional observations makes it difficult to identify the specific damage modes occurring inside the thin plate specimen in real time and accurately during the test, and it is also impossible to accurately locate the damage initiation point and evolution process, resulting in insufficient accuracy and reliability in evaluating the interlaminar properties of thin plates.

[0003] Therefore, there is a need in the existing technology to improve the method for interlaminar damage identification and failure determination of a composite laminated thin plate. Summary of the Invention

[0004] To address the technical problems of insufficient accuracy and reliability in the evaluation of interlaminar performance of thin plates in existing technologies, embodiments of the present invention provide a method, apparatus, equipment, and medium for identifying interlaminar damage and determining failure in composite laminated thin plates. The technical solution is as follows:

[0005] S1 collects acoustic emission signals of composite laminated thin plates in short beam shear tests, and extracts amplitude intensity and peak frequency based on the acoustic emission signals;

[0006] S2 classifies and identifies damage types during interlaminar shear failure based on amplitude intensity and peak frequency.

[0007] S3 calculates the relative cumulative count of acoustic emission signals for each type of damage and simultaneously calculates the load change increment, constructing the relationship curves between the relative cumulative count of different damages, the load change increment, and time.

[0008] S4 determines the damage initiation time based on the initial change characteristic point of the relative cumulative count curve in the relationship curve, and combines the abrupt change characteristics of the load increment curve to jointly determine the interlaminar shear failure point, and outputs the load value of the failure point as the ultimate load of the interlaminar shear strength.

[0009] In some implementations, in S1, extracting the amplitude intensity and peak frequency based on the acoustic emission signal includes:

[0010] Voltage extrema are obtained from acoustic emission signals, and these extrema are converted into amplitude intensity. The peak frequency of each signal is then calculated based on fast Fourier transform of the acoustic emission signals.

[0011] In some implementations, in S2, the damage categories include: matrix cracking, fiber-matrix debonding or delamination, and fiber breakage.

[0012] In some implementations, when classifying based on amplitude intensity and peak frequency, an amplitude intensity threshold range and a peak frequency interval are set:

[0013] When the amplitude intensity is between 0-60dB and the peak frequency is between 0-80Hz, it is determined to be matrix cracking;

[0014] When the amplitude intensity is between 0-100dB and the peak frequency is between 80-225kHz, it is determined to be fiber-matrix debonding or delamination.

[0015] When the amplitude intensity is greater than 0-80 dB and the peak frequency is higher than 250 kHz, fiber damage is determined. In some embodiments, in S3, the formula for calculating the relative cumulative count is:

[0016]

[0017] in, Let be the cumulative sum of AE counts at time t. This represents the final total number of AE counts.

[0018] In some implementations, in S3, the formula for calculating the load change increment is:

[0019]

[0020] in, for The load borne by the specimen at any given moment. It is the time interval for calculating the increment.

[0021] In some implementations, in S4, when determining the interlaminar shear failure point, when the fiber-resin debonding signal has appeared and continues to exist, the relative cumulative count curve of fiber failure increases from the initial time to the peak and then stops increasing, while the load increment rapidly decreases to close to 0, the corresponding time is determined to be the interlaminar shear failure point.

[0022] On the other hand, a device for identifying and determining interlaminar damage and failure of composite laminated thin plates is provided. This device is applied to a method for identifying and determining interlaminar damage and failure of composite laminated thin plates. The device includes:

[0023] The acquisition module is configured to acquire acoustic emission signals of composite laminated thin plates in short beam shear tests, and extract amplitude intensity and peak frequency based on the acoustic emission signals.

[0024] The classification module is configured to classify and identify damage types during interlaminar shear failure based on amplitude intensity and peak frequency.

[0025] The plotting module is configured to calculate the relative cumulative count of acoustic emission signals for each type of damage, and simultaneously calculate the load change increment, constructing curves showing the relationship between the relative cumulative count of different damages, the load change increment, and time.

[0026] The judgment module is configured to determine the damage initiation time based on the initial change feature points of the relative cumulative count curve in the relationship curve, and to collaboratively determine the interlaminar shear failure point by combining the abrupt change characteristics of the load increment curve, and output the load value of the failure point as the ultimate load of the interlaminar shear strength.

[0027] On the other hand, a computer device is provided, the computer device comprising: a processor; a memory storing computer-readable instructions, wherein when the computer-readable instructions are executed by the processor, any one of the methods described above for identifying interlaminar damage and determining failure in composite laminated thin plates is implemented.

[0028] On the other hand, a computer-readable storage medium is provided, wherein at least one instruction is stored in the storage medium, the at least one instruction being loaded and executed by a processor to implement any of the above-described methods for identifying interlaminar damage and determining failure in composite laminated thin plates.

[0029] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0030] (1) Breaking through the limitations of traditional macroscopic curve criteria, damage mechanisms are distinguished in real time based on the dual characteristic parameters of acoustic emission signal amplitude and frequency, realizing the visual tracking of microscopic damage evolution process;

[0031] (2) Eliminate the differences in the magnitude of different damage signals by using a cumulative counting algorithm to achieve an equivalent comparison of the damage accumulation process;

[0032] (3) Establish a spatiotemporal correlation mechanism between the cumulative damage curve and the incremental load curve. Through dual verification of damage initiation timing and load mutation characteristics, the risk of misjudgment of failure point is significantly reduced, and the accuracy of interlaminar shear strength calculation is ensured. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart of a method for identifying interlaminar damage and determining failure in composite laminated thin plates provided by an embodiment of the present invention;

[0035] Figure 2 This is a graph showing the relationship between displacement and load tests for different samples provided in the embodiments of the present invention;

[0036] Figure 3 This is a damage identification status diagram provided in an embodiment of the present invention;

[0037] Figure 4 This is the time-relative cumulative count curve / load increment curve provided in the embodiments of the present invention;

[0038] Figure 5 The inter-story shear failure limit load determined based on time-relative cumulative counting curves and load increment curves provided in this embodiment of the invention is... A schematic diagram;

[0039] Figure 6 This is a schematic diagram of a structure for identifying interlaminar damage and determining failure in a composite laminated thin plate according to an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0041] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0042] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0043] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning.

[0044] In this embodiment of the invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0045] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0046] This invention provides a method for identifying interlaminar damage and determining failure in composite laminated thin plates. This method can be implemented using a computer device, which can be a terminal or a server. Figure 1 The flowchart shown is for a method to identify interlaminar damage and determine failure in composite laminated thin plates. The processing flow of this method may include the following steps:

[0047] S1 collects acoustic emission signals of composite laminated thin plates in short beam shear tests, and extracts amplitude intensity and peak frequency based on the acoustic emission signals;

[0048] S2 classifies and identifies damage types during interlaminar shear failure based on amplitude intensity and peak frequency.

[0049] S3 calculates the relative cumulative count of acoustic emission signals for each type of damage and simultaneously calculates the load change increment, constructing the relationship curves between the relative cumulative count of different damages, the load change increment, and time.

[0050] S4 determines the damage initiation time based on the initial change characteristic point of the relative cumulative count curve in the relationship curve, and combines the abrupt change characteristics of the load increment curve to jointly determine the interlaminar shear failure point, and outputs the load value of the failure point as the ultimate load of the interlaminar shear strength.

[0051] Furthermore, in S1, the extraction of amplitude intensity and peak frequency based on the acoustic emission signal includes:

[0052] Voltage extrema are obtained from acoustic emission signals, and these extrema are converted into amplitude intensity. The peak frequency of each signal is then calculated based on fast Fourier transform of the acoustic emission signals.

[0053] Furthermore, in S2, the damage categories include: matrix cracking, fiber-matrix debonding or delamination, and fiber failure. Specifically, when classifying based on amplitude intensity and peak frequency, an amplitude intensity threshold range and a peak frequency range are set:

[0054] When the amplitude intensity is between 50-80dB and the peak frequency is between 100-200kHz, it is determined to be matrix cracking;

[0055] When the amplitude intensity is between 80-120dB and the peak frequency is between 200-400kHz, it is determined to be fiber-matrix debonding or delamination.

[0056] When the amplitude intensity is greater than 120dB and the peak frequency is higher than 400kHz, it is determined to be fiber damage.

[0057] Those skilled in the art should understand that the range determined above can be adaptively adjusted based on different materials, and the methods of classification and judgment based on different amplitude intensities and peak frequencies are all within the protection scope of this invention.

[0058] Furthermore, in S3, the relative cumulative count of acoustic emission signals for different damage types is calculated, demonstrating the evolution of damage with continuous loading and resolving the problem of large differences in signal magnitudes between different damage mechanisms, making comparison difficult. The formula for calculating the relative cumulative count is as follows:

[0059]

[0060] in, Let be the cumulative sum of AE counts at time t. This represents the final total number of AE counts.

[0061] Furthermore, in S3, the formula for calculating the load change increment is:

[0062]

[0063] in, for The load borne by the specimen at any given moment. It is the time interval for calculating the increment.

[0064] Furthermore, in S4, when determining the interlaminar shear failure point, when the fiber-resin debonding signal has appeared and continues to exist, the relative cumulative count curve of fiber failure increases from the initial time to the peak and then stops increasing, while the load increment rapidly decreases to close to 0, at this time the corresponding time is determined to be the interlaminar shear failure point.

[0065] The present invention will be further explained below with reference to specific embodiments.

[0066] Six-layer biaxially oriented aramid fiber-reinforced resin matrix composite laminates were prepared using vacuum-assisted resin transfer molding (VARTM), with an average sample thickness of 2.35 mm. Short beam shear tests were conducted according to ASTM D2344. Acoustic emission sensors were positioned at the sample supports, and three sets of sensors were used for data acquisition. The acoustic emission signal with the optimal signal-to-noise ratio was selected from the three sets for analysis. Figure 2 The load-displacement curves of the six parallel specimens shown did not exhibit the 30% decrease in ultimate load as described in the specification; instead, they showed a slight decrease followed by a continuous increase.

[0067] like Figure 3 As shown, based on the amplitude intensity and FFT peak frequency of the acoustic emission signal, the signal of any specimen can be divided into three categories. Combining relevant literature, the signals are further classified into matrix cracking, debonding / delamination, and fiber failure. The time-relative cumulative count curves and time-load increment curves of the acoustic emission signals for different damage types are plotted as follows: Figure 4 As shown, the matrix cracking signal appears first and accompanies the entire test process. A significant increase occurs at time point I, and the corresponding load increment curve also grows at a significantly faster rate. This is because the load applied by the loading head to the middle of the specimen begins to be fully transferred to both ends, generating interlaminar shear stress. Under the action of shear stress, fine cracks begin to appear in the matrix. The fiber-resin debonding signal appears from time point II until the end of the test. At this time, the load increment curve has begun to enter the descending phase, showing a gradual decreasing trend, indicating that interlaminar damage has begun to occur, hence the rapid increase in the fiber-resin debonding signal. The relative cumulative count curve of fiber failure is different. Starting at time point III, it slightly lags behind the fiber-resin interface debonding, and after rapidly increasing to a peak value in a short time, it almost stops growing. During this process, the load increment rapidly decreases to near zero. This indicates that the specimen reaches the interlaminar shear strength and undergoes interlaminar shear failure, with the load transferred to the fiber causing tensile fracture. Figure 5 As shown, based on the inter-story shear failure point determined above, the ultimate load corresponding to the inter-story shear strength can be obtained from the load-time curve. Then, the interlaminar shear strength of the composite laminate can be calculated.

[0068] Figure 6This is a block diagram illustrating an interlaminar damage identification and failure determination device for composite laminated thin plates according to an exemplary embodiment. The device is used in a method for interlaminar damage identification and failure determination of composite laminated thin plates. (Refer to...) Figure 6 The device includes:

[0069] Acquisition module 100 is configured to acquire acoustic emission signals of composite laminated thin plates in short beam shear tests, and extract amplitude intensity and peak frequency based on acoustic emission signals.

[0070] Classification module 200 is configured to classify and identify damage types during interlaminar shear failure based on amplitude intensity and peak frequency.

[0071] The plotting module 300 is configured to calculate the relative cumulative count of acoustic emission signals for each type of damage, and simultaneously calculate the load change increment, constructing the relationship curves between the relative cumulative count of different damages, the load change increment, and time.

[0072] The judgment module 400 is configured to determine the damage initiation time based on the initial change feature points of the relative cumulative count curve in the relationship curve, and to collaboratively determine the interlaminar shear failure point by combining the abrupt change characteristics of the load increment curve, and output the load value of the failure point as the ultimate load of the interlaminar shear strength.

[0073] Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention, such as... Figure 7 As shown, the computer device may include the above-mentioned Figure 6 The illustrated device for identifying interlaminar damage and determining failure in composite laminated thin plates. Optionally, the computer device 410 may include a first processor 2001.

[0074] Optionally, the computer device 410 may also include a memory 2002 and a transceiver 2003.

[0075] The first processor 2001, memory 2002, and transceiver 2003 can be connected via a communication bus.

[0076] The following is combined with Figure 7 A detailed description of each component of computer device 410 is provided below:

[0077] The first processor 2001 is the control center of the computer device 410. It can be a single processor or a collective term for multiple processing elements. For example, the first processor 2001 can be one or more central processing units (CPUs), application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement embodiments of the present invention, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0078] Optionally, the first processor 2001 can perform various functions of the computer device 410 by running or executing software programs stored in the memory 2002 and calling data stored in the memory 2002.

[0079] In a specific implementation, as one example, the first processor 2001 may include one or more CPUs, for example... Figure 7 CPU0 and CPU1 are shown in the diagram.

[0080] In a specific implementation, as one example, the computer device 410 may also include multiple processors, for example... Figure 7 The first processor 2001 and the second processor 2004 are shown in the diagram. Each of these processors can be a single-core processor or a multi-core processor. Here, a processor can refer to one or more devices, circuits, and / or processing cores used to process data (such as computer program instructions).

[0081] The memory 2002 is used to store the software program that executes the present invention, and is controlled by the first processor 2001 to execute it. The specific implementation method can be referred to the above method embodiment, and will not be repeated here.

[0082] Optionally, the memory 2002 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 2002 may be integrated with the first processor 2001 or may exist independently and be connected via the interface circuit of the computer device 410. Figure 7 (Not shown in the image) is coupled to the first processor 2001, and this embodiment of the invention does not specifically limit this.

[0083] The transceiver 2003 is used to communicate with network devices or with terminal devices.

[0084] Alternatively, transceiver 2003 may include a receiver and a transmitter. Figure 7 (Not shown separately). The receiver is used to implement the receiving function, and the transmitter is used to implement the transmitting function.

[0085] Optionally, the transceiver 2003 can be integrated with the first processor 2001, or it can exist independently and be connected via the interface circuit of the computer device 410. Figure 7 (Not shown in the image) is coupled to the first processor 2001, and this embodiment of the invention does not specifically limit this.

[0086] It should be noted that, Figure 7 The structure of the computer device 410 shown does not constitute a limitation on the router. Actual knowledge structure identification devices may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0087] Furthermore, the technical effects of the computer device 410 can be referenced from the technical effects of the composite material laminated thin plate interlaminar damage identification and failure determination method described in the above method embodiments, and will not be repeated here.

[0088] It should be understood that the first processor 2001 in the embodiments of the present invention may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0089] It should also be understood that the memory in the embodiments of the present invention can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0090] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0091] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0092] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0093] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0094] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0095] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0096] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0097] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0098] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0099] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0100] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for identifying interlaminar damage and determining failure in composite laminated thin plates, characterized in that, The method includes: S1 collects acoustic emission signals of composite laminated thin plates in short beam shear tests, and extracts amplitude intensity and peak frequency based on the acoustic emission signals; S2 classifies and identifies the damage type during the interlaminar shear failure process based on the amplitude intensity and the peak frequency; S3 calculates the relative cumulative count of acoustic emission signals for each type of damage and simultaneously calculates the load change increment, constructing the relationship curves between the relative cumulative count of different damages, the load change increment, and time. S4 determines the damage initiation time based on the initial change feature point of the relative cumulative count curve in the relationship curve, and combines the abrupt change feature of the relationship curve between the load change increment and time to jointly determine the interlaminar shear failure point, and outputs the failure point load value as the ultimate load of the interlaminar shear strength. in, In S3, the relative cumulative count is the ratio of the cumulative count value of acoustic emission signals of a single damage type at time t to the final total value of acoustic emission signals of that type of damage. In S4, based on the amplitude intensity of the acoustic emission signal and the peak frequency of the FFT, the signal of any specimen is divided into three categories: matrix cracking, debonding / delamination, and fiber failure. Time-relative cumulative count curves and time-load increment curves for different damage types are plotted. The abrupt change characteristics of different curves are combined to collaboratively determine the interlaminar shear failure point. The matrix cracking signal was present throughout the entire process and showed a significant increase for the first time at time point I, while the rate of increase of the synchronous load increment curve accelerated. The fiber-resin debonding signal began to appear continuously at time point II, at which time the load increment curve showed a downward trend and gradually decreased. The fiber failure signal begins at time point III. The relative cumulative count curve of fiber failure rises rapidly to its peak and then remains constant. The synchronous load increment drops rapidly to near zero. This moment is determined to be the interlaminar shear failure point.

2. The method for identifying interlaminar damage and determining failure in composite laminated thin plates according to claim 1, characterized in that, In S1, extracting the amplitude intensity and peak frequency based on the acoustic emission signal includes: The voltage extreme values ​​are obtained based on the acoustic emission signals, and the voltage extreme values ​​are converted into amplitude intensity. The peak frequency of each signal is calculated based on the fast Fourier transform of the acoustic emission signals.

3. The method for identifying interlaminar damage and determining failure in composite laminated thin plates according to claim 1, characterized in that, In S2, the damage categories include: matrix cracking, fiber-matrix debonding or delamination, and fiber damage.

4. The method for identifying interlaminar damage and determining failure in composite laminated thin plates according to claim 3, characterized in that, When classifying based on the amplitude intensity and the peak frequency, an amplitude intensity threshold range and a peak frequency interval are set: When the amplitude intensity is between 0-60dB and the peak frequency is between 0-80Hz, it is determined to be matrix cracking; When the amplitude intensity is between 0-100dB and the peak frequency is between 80-225kHz, it is determined to be fiber-matrix debonding or delamination. When the amplitude intensity is greater than 0-80dB and the peak frequency is higher than 250kHz, it is determined to be fiber damage.

5. The method for identifying interlaminar damage and determining failure in composite laminated thin plates according to claim 1, characterized in that, In S3, the formula for calculating the load change increment is: ； in, for The load borne by the specimen at any given moment. It is the time interval for calculating the increment.

6. A device for identifying and determining interlaminar damage and failure of composite laminated thin plates, wherein the device is used to implement the method for identifying and determining interlaminar damage and failure of composite laminated thin plates as described in any one of claims 1-5, characterized in that, The device includes: The acquisition module is configured to acquire acoustic emission signals of composite laminated thin plates in short beam shear tests, and extract amplitude intensity and peak frequency based on the acoustic emission signals. The classification module is configured to classify and identify damage types during interlaminar shear failure based on amplitude intensity and peak frequency. The plotting module is configured to calculate the relative cumulative count of acoustic emission signals for each type of damage, and simultaneously calculate the load change increment, constructing curves showing the relationship between the relative cumulative count of different damages, the load change increment, and time. The judgment module is configured to determine the damage initiation time based on the initial change feature points of the relative cumulative count curve in the relationship curve, and to collaboratively determine the interlaminar shear failure point by combining the abrupt change characteristics of the load increment curve, and output the load value of the failure point as the ultimate load of the interlaminar shear strength.

7. A computer device, characterized in that, The computer device includes: processor; A memory storing computer-readable instructions that, when executed by the processor, implement the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains program code that can be invoked by a processor to execute the method as described in any one of claims 1 to 5.

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