Metal material tensile damage evaluation method and device based on acoustic emission

Abstract

The invention discloses a metal material tensile damage evaluation method and device based on acoustic emission, and belongs to the technical field of acoustic emission monitoring and damage evaluation. According to the method, an acoustic emission monitoring system is used for collecting acoustic emission signals in the metal material stretching process, a new acoustic emission parameter Q capable of accurately and effectively identifying different damage degrees in the material stretching process is provided, and the metal material stretching damage online damage method based on the new acoustic emission parameter Q is established. The new acoustic emission parameter Q is not only unrelated to the artificially set acoustic emission system threshold value, but also can fully consider the evolution law of a plurality of typical time domain and frequency domain characteristics in the acoustic emission signal, so that the change process of different damage degrees in the metal material stretching process can be more accurately and comprehensively represented and evaluated.

Description

Technical Field

[0001] The invention belongs to the technical field of acoustic emission monitoring and damage evaluation, and in particular relates to a method and device for evaluating tensile damage of metal materials based on acoustic emission. Background Art

[0002] Crack damage identification of metal structures is a very important research direction in the field of engineering, which involves multiple disciplines such as materials science, mechanics, computer science, and data analysis. Metal structures are widely used in aerospace, automobile manufacturing, bridge construction, shipbuilding, and petrochemical industries. The stability and safety of these structures are directly related to personnel safety and economic interests. During long-term use, metal structures may develop cracks due to fatigue, corrosion, overload, etc. If these cracks are not discovered and treated in time, they may cause structural failure or even catastrophic accidents. However, cracks in metal structures are usually very small in the early stages and difficult to observe with the naked eye. Over time, cracks may gradually expand and eventually lead to structural damage. Therefore, timely detection and evaluation of crack damage is of great significance for preventing safety accidents of metal structures.

[0003] Non-destructive testing (NDT) technology is an important means to detect internal and surface defects of materials and components without destroying their structural properties. Although traditional non-destructive testing methods such as ultrasonic testing and radiographic testing can detect cracks to a certain extent, these methods belong to the category of offline testing and need to be inspected when the equipment is shut down. The detection cost is high and the efficiency is low, and it is impossible to achieve online evaluation of crack damage. Acoustic emission (AE) is a phenomenon based on the release of strain energy in the form of elastic waves when materials deform or crack during stress. Acoustic emission technology uses highly sensitive sensors to receive these elastic waves, converts them into digital signals using a detection system, and performs further signal processing and analysis. The generation of acoustic emission signals is directly related to the deformation and fracture mechanism of the material, so acoustic emission technology can be used to detect internal damage and crack propagation of materials. Compared with traditional non-destructive testing methods, acoustic emission technology is an online dynamic defect detection method that has unique advantages in detecting material deformation and crack damage and is widely used in metal material damage evaluation.

[0004] By conducting acoustic emission monitoring experiments during the tensile process of metal materials and analyzing the characteristics of acoustic emission signals generated during the tensile process, such as amplitude, rise time, energy and other parameters, it is possible to identify the various stages of material tensile damage to a certain extent and provide early warning for the arrival of crack extension and fracture stages, which is of vital importance to ensuring equipment safety. However, many parameters other than amplitude depend to a large extent on the artificially set threshold value of the acoustic emission system. For example, acoustic emission characteristic parameters such as rise time, duration and count are closely related to the size of the threshold value. Secondly, the traditional method of using a single acoustic emission parameter for damage characterization does not fully consider the evolution law of multiple time domain and frequency domain characteristics, so it is easy to cause errors in damage evaluation and it is difficult to accurately evaluate the degree of tensile damage. The above factors have greatly limited the development of metal material damage evaluation technology based on acoustic emission parameters, as well as the engineering application of acoustic emission monitoring in metal structure damage evaluation. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method and device for evaluating tensile damage of metal materials based on acoustic emission, so as to solve the problems of large errors and human factors in the traditional damage characterization using a single acoustic emission parameter in the prior art. The present invention proposes a new parameter Q that is independent of the threshold value of the acoustic emission system and can fully consider the evolution law of the acoustic emission time domain and frequency domain characteristics. The online characterization of tensile damage is performed based on the evolution law of the new acoustic emission parameter Q over time, thereby realizing accurate identification and evaluation of the degree of metal damage.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for evaluating tensile damage of metal materials based on acoustic emission comprises the following steps: S1, collecting acoustic emission signals, wherein the acoustic emission signals are obtained through an acoustic emission monitoring experiment during the stretching process of a metal material; S2, based on the acoustic emission signal, obtaining a peak factor of the acoustic emission signal, an information entropy of the acoustic emission signal, and a centroid frequency of the acoustic emission signal, multiplying the peak factor of the acoustic emission signal and the information entropy of the acoustic emission signal, dividing the product by the centroid frequency of the acoustic emission signal, and obtaining an acoustic emission parameter characterizing tensile damage; S3, evaluate the tensile damage degree of metal materials through the evolution law of acoustic emission parameters and the normalized curve of the cumulative value of acoustic emission parameters.

[0007] A further improvement of the present invention is: Preferably, in S2, the calculation formula of the acoustic emission parameter characterizing the tensile damage is: (1) In the formula, QTo characterize the acoustic emission parameters of tensile damage, PF is the peak factor of the acoustic emission signal, H AE (V) is the information entropy of the acoustic emission signal, f c is the centroid frequency of the acoustic emission signal.

[0008] Preferably, in S2, the information entropy of the acoustic emission signal is the ratio of the peak value of the acoustic emission signal to the root mean square value of the signal.

[0009] Preferably, in S2, the peak factor calculation formula of the acoustic emission signal is: (2) In the formula, PF is the peak factor of the acoustic emission signal, P max is the peak value of the acoustic emission signal, RMS is the root mean square of the acoustic emission signal, X i The signal is i Sample values, N is the total number of samples.

[0010] Preferably, in S2, the calculation formula of the information entropy of the acoustic emission signal is: (3) In the formula, H AE (V) is the information entropy of the acoustic emission signal; p(V i ) Represents every possible voltage value V i The probability in each group interval; b = 2, indicating that the dimension is bits.

[0011] Preferably, in S2, the centroid frequency calculation formula of the acoustic emission signal is: (4) In the formula, f c is the acoustic emission centroid frequency, f i The signal is i frequency components, E(f i ) is the frequency corresponding to f i The energy value, N is the total number of frequency components.

[0012] Preferably, in S3, when the acoustic emission parameter first increases and then decreases, and the value of the entire process is between 0.1 and 0.2, the metal material reaches the yield stage during the stretching process.

[0013] Preferably, in S3, when the acoustic emission parameter rises sharply, the normalized curve of the cumulative value of the acoustic emission parameter increases sharply, and the value of the acoustic emission parameter is greater than 0.2, cracks appear in the metal material during the stretching process.

[0014] Preferably, in S1, the acoustic emission monitoring experiment is performed by a metal material tensile damage monitoring system.

[0015] A metal material tensile damage evaluation device based on acoustic emission, comprising: A collection module, used for collecting acoustic emission signals, wherein the acoustic emission signals are obtained through an acoustic emission monitoring experiment during the stretching process of a metal material; A calculation module is used to obtain a peak factor of the acoustic emission signal, an information entropy of the acoustic emission signal, and a centroid frequency of the acoustic emission signal based on the acoustic emission signal, multiply the peak factor of the acoustic emission signal and the information entropy of the acoustic emission signal, divide the product by the centroid frequency of the acoustic emission signal, and obtain an acoustic emission parameter characterizing tensile damage; The evaluation module is used to evaluate the tensile damage degree of metal materials through the evolution law of acoustic emission parameters and the normalized curve of the cumulative value of acoustic emission parameters.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses an online evaluation method for tensile damage of metal materials based on acoustic emission. The acoustic emission signal in the tensile process of the metal material is collected by using an acoustic emission monitoring system, a new acoustic emission parameter Q that can accurately and effectively identify different degrees of damage in the material tensile process is proposed, and an online evaluation method for tensile damage of metal materials based on the new acoustic emission parameter Q is established. The new acoustic emission parameter Q is not only independent of the artificially set threshold value of the acoustic emission system, but also can fully consider the evolution law of multiple typical time domain and frequency domain characteristics in the acoustic emission signal, so it can more accurately and comprehensively characterize and evaluate the change process of different degrees of damage in the tensile process of the metal material. In addition, the method is simple, easy to implement, and can be applied to the online characterization of tensile damage of metal materials. Therefore, the method of the present invention has great development prospects and a wide range of application scenarios in acoustic emission structural health monitoring and damage assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of an online evaluation method for tensile damage of metal materials based on acoustic emission of the present invention; Figure 2 This is the experimental layout diagram for acoustic emission monitoring of metal materials during the stretching process.

[0018] Among them, 1- tensile test platform; 2- sample; 3- sensor; 4- preamplifier; 5- acoustic emission acquisition instrument; 6- computer.

[0019] Figure 3 This is a diagram showing the tensile damage evaluation results of Example 1 of the present invention.

[0020] Figure 4 This is a diagram showing the tensile damage evaluation results of Example 2 of the present invention. DETAILED DESCRIPTION

[0021] In the following, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features.

[0022] The co-shooting method provided in the embodiment of the present application can be applied to terminal devices such as mobile phones, tablet computers, wearable devices, vehicle-mounted devices, augmented reality (AR) / virtual reality (VR) devices, laptop computers, ultra-mobile personal computers (UMPC), netbooks, personal digital assistants (PDA), etc. The embodiment of the present application does not impose any restrictions on the specific type of the terminal device.

[0023] It should be noted that the terms "first", "second", etc. in the specification and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] As mentioned in the background technology, the traditional method of using a single acoustic emission parameter to characterize damage does not fully consider the evolution laws of multiple time domain and frequency domain characteristics. Therefore, it is easy to cause errors in damage evaluation and it is difficult to accurately evaluate the degree of tensile damage.

[0025] To solve the above problems, see Figure 1 , the present invention discloses a method for evaluating tensile damage of metal materials based on acoustic emission, comprising the following steps; S1, collecting and acquiring acoustic emission signals, wherein the acoustic emission signals are obtained through an acoustic emission monitoring experiment during the stretching process of a metal material.

[0026] S2, extracting acoustic emission features based on the acoustic emission signal, wherein the acoustic emission features include a peak factor of the acoustic emission signal, an information entropy of the acoustic emission signal, and a centroid frequency of the acoustic emission signal, multiplying the peak factor of the acoustic emission signal and the information entropy of the acoustic emission signal, and dividing the product by the centroid frequency of the acoustic emission signal to obtain an acoustic emission parameter characterizing the tensile damage Q ; S3, starting from the tensile test monitoring, according to the signal arrival time sequence, obtain the acoustic emission parameters Q The change characteristics of the metal material tensile damage are used to identify and evaluate the material online. Q The evolution law of tensile damage is used to evaluate the degree of tensile damage.

[0027] In some embodiments of the present invention, in S1, the acoustic emission signal generated during the stretching process of the metal material is collected by using a broadband sensor.

[0028] In some embodiments of the present invention, the acoustic emission monitoring experiment is carried out by a metal material tensile damage monitoring system. Referring to FIG. 2 , a metal material tensile damage monitoring system using acoustic emission technology is shown, and the system includes a stretching platform 1, a sensor 3, a preamplifier 4, an acoustic emission acquisition instrument 5, and a computer 6.

[0029] See also Figure 2 During the tensile test, the sample 2 is placed on the tensile platform 1, the sensor 3 is fixed on the sample 2 through a coupling agent, and both ends of the sample 2 are fixed by the tensile device on the tensile platform 1. It also includes an acoustic emission acquisition instrument 5, and a preamplifier 4 is arranged between the acoustic emission acquisition instrument 5 and the sample 2. The preamplifier 4 is used to amplify the signal emitted by the sensor 3 and send it to the acoustic emission acquisition instrument 5. The acoustic emission acquisition instrument 5 is electrically connected to a computer 6. The computer 6 obtains the acoustic emission signal and extracts the acoustic emission characteristics from it.

[0030] As a preferred solution, the sensor 3 is a wideband sensor, which is a device used to convert changes in certain physical quantities (such as sound, light, magnetism, temperature, etc.) into electrical signal outputs. The sensor is a sensor that can detect and respond to signals within a wide frequency range, and the sensor can usually cover a frequency range of kHz or MHz levels.

[0031] In some embodiments of the present invention, in S2, typical characteristic parameters are extracted from each acoustic emission signal obtained after the material tensile test begins, and the acoustic emission parameters characterizing the tensile damage are calculated based on these typical characteristics and formula (1): Q , acoustic emission parameters characterizing tensile damage Q The calculation formula is: (1) In the formula, Q Acoustic emission parameters to characterize tensile damage; PF is the peak factor of the acoustic emission signal; H AE (V) is the information entropy of the acoustic emission signal; f c is the centroid frequency of the acoustic emission signal; Furthermore, PF It is the ratio of the peak value of the acoustic emission signal to its root mean square, describing the degree of the peak value of the acoustic emission waveform relative to its average energy level. It is a time domain parameter and has nothing to do with the system threshold value. Its calculation formula is: (2) In the formula, PF is the peak factor of the acoustic emission signal; P max is the peak value of the acoustic emission signal; RMS is the root mean square of the acoustic emission signal; X i The signal is i Sample values, N is the total number of samples; Furthermore, H AE (V) The characteristic parameter that characterizes the complexity and randomness of the acoustic emission waveform is a time domain parameter and has nothing to do with the system threshold value. Its calculation formula is: (3) In the formula, H AE (V) It is the information entropy of the discrete distribution of acoustic emission waveform, referred to as acoustic emission entropy; p(V i ) Represents every possible voltage value V i The probability in each group interval; b=2, indicating that the dimension is bit; for the specific calculation method of information entropy, please refer to the patent publication number CN114384156A.

[0032] Furthermore, fc It is a parameter that describes the center position of the signal frequency distribution. It is usually used to indicate the main frequency or average frequency of the signal. It is a frequency domain parameter and has nothing to do with the system threshold value. Its calculation formula is: (4) In the formula, f c is the acoustic emission centroid frequency; f i The signal is i frequency components; E(f i ) is the frequency corresponding to f i The energy value is obtained by converting the waveform into a spectrum. N is the total number of frequency components; In some embodiments of the present invention, in S3, the acoustic emission parameters are obtained by calculation Q To evaluate the tensile damage of metal materials. Q When the value of increases significantly at first and then decreases gradually, and the value of this change process remains in the range of 0.1 to 0.2, it is considered a sign that the damage degree of the metal material in the tensile process has reached the yield stage; when the acoustic emission parameter Q The value of Q The normalized curve of the cumulative value suddenly increases sharply, and Q When the value of exceeds 0.2 and reaches the range of 0.2-0.6, especially when its maximum value reaches above 0.5, it is determined that the damage degree of the material during the tensile process has progressed to the stage of crack propagation and even fracture, indicating a significant degradation of the material performance. Specifically, the key feature for evaluating the damage of metal materials is the acoustic emission parameter Q A significant peak and a sharp rise in its value.

[0033] The second aspect of the present invention discloses a metal material tensile damage evaluation device based on acoustic emission, comprising: A collection module, used for collecting acoustic emission signals, wherein the acoustic emission signals are obtained through an acoustic emission monitoring experiment during a metal material drawing process; A calculation module is used to obtain a peak factor of the acoustic emission signal, an information entropy of the acoustic emission signal, and a centroid frequency of the acoustic emission signal based on the acoustic emission signal, multiply the peak factor of the acoustic emission signal and the information entropy of the acoustic emission signal, divide the product by the centroid frequency of the acoustic emission signal, and obtain an acoustic emission parameter characterizing tensile damage; The evaluation module is used to evaluate the tensile damage degree of metal materials through the evolution law of acoustic emission parameters and the normalized curve of the cumulative value of acoustic emission parameters.

[0034] The following is further described in conjunction with specific embodiments.

[0035] Example 1 like Figure 1 As shown in the figure, a uniaxial tensile test of 2.25Cr1Mo0.25V steel was carried out at room temperature, and a continuous tensile loading test was performed with a constant loading rate. At the same time, an acoustic emission broadband sensor was used to record the acoustic emission signal during the stretching process. The obtained acoustic emission signal data was imported into a computer and the acoustic emission characteristic parameters were extracted.

[0036] Combined with Figure 2 ,use Figure 1 The acoustic emission data obtained from the tensile test of the metal material shown in the figure, the extraction of acoustic emission characteristic parameters and the new acoustic emission parameters Q The calculation process and acoustic emission parameters Q The tensile damage strength characterization results are described in detail. The specific process is as follows: Step 1: Use acoustic emission technology to carry out acoustic emission monitoring experiments during the tensile process of 2.25Cr1Mo0.25V steel to obtain acoustic emission signals.

[0037] Step 2: The acoustic emission signals obtained from the tensile test of 2.25Cr1Mo0.25V steel are processed separately to extract the acoustic emission characteristic parameters. According to formula (1), the new acoustic emission parameters for characterizing the tensile damage of 2.25Cr1Mo0.25V steel are calculated. Q ; Step 3: Plot the acoustic emission parameters Q The evolution law of arrival time is based on the acoustic emission parameters Q The changing characteristics of the tensile damage of 2.25Cr1Mo0.25V steel were characterized.

[0038] Figure 3 The acoustic emission parameters are shown in Q The tensile damage characterization results of 2.25Cr1Mo0.25V steel. Figure 3 It can be seen that the acoustic emission parameters Q The evolution law includes two obvious characteristics.

[0039] The first characteristic point: As the mechanical property curve of 2.25Cr1Mo0.25V steel is about to enter the yield stage, the acoustic emission parameters Q Then a clear peak appeared, and its value stabilized in the range of 0.1 to 0.2, and then gradually decreased. Q In the normalized curve of the cumulative value, it can be observed that the slope of the corresponding stage becomes larger, which usually means that at this particular stage, the parameter QThis key parameter change can be used as a reliable evaluation index to assess the damage degree of 2.25Cr1Mo0.25V steel during the tensile process to reach the yield stage.

[0040] The second characteristic point: As the mechanical property curve of 2.25Cr1Mo0.25V steel enters the crack propagation and fracture stage, the acoustic emission parameters Q It increases sharply, and its value ranges from 0.2 to 0.6, with a maximum value of 0.544. Q In the normalized curve of the cumulative value, a sudden increase in the slope of the corresponding stage can be observed, which usually means that at this particular stage, the parameter Q The value of has significantly increased. This key parameter change can be used as a reliable evaluation indicator to assess whether the damage degree of 2.25Cr1Mo0.25V steel during the tensile process reaches the stage of crack extension or even fracture.

[0041] Therefore, based on the acoustic emission parameters Q The evolution law of the acoustic emission parameters can effectively characterize the damage degree of 2.25Cr1Mo0.25V steel during the tensile process. The key characteristic point of the material damage degree in this case is the acoustic emission parameters Q The significant peaks and sharp rises in parameter values.

[0042] Example 2 The uniaxial tensile test of 316 steel was carried out at room temperature. A continuous tensile loading test was performed with a constant loading rate. An acoustic emission broadband sensor was used to record the acoustic emission signals during the stretching process. The acquired acoustic emission signal data were imported into a computer and the acoustic emission characteristic parameters were extracted.

[0043] Combined with Figure 2 ,use Figure 1 The acoustic emission data obtained from the tensile test of the metal material shown in the figure, the extraction of acoustic emission characteristic parameters and the new acoustic emission parameters Q The calculation process and acoustic emission parameters Q The tensile damage strength characterization results are described in detail. The specific process is as follows: Step 1: See Figure 1 , the acoustic emission technology was used to carry out the acoustic emission monitoring experiment of the 316 steel tensile process and obtain the acoustic emission signal.

[0044] Step 2: Process the acoustic emission signals obtained from the 316 steel tensile test separately, extract the acoustic emission characteristic parameters, and calculate the new acoustic emission parameters representing the tensile damage of 316 steel according to formula (1): Q ; Step 3: Plot the acoustic emission parameters Q The evolution law of arrival time is based on the acoustic emission parametersQ The changing characteristics of the tensile damage of 316 steel are characterized.

[0045] Figure 4 The acoustic emission parameters are shown in Q The tensile damage characterization results of 316 steel. Figure 4 It can be seen that the acoustic emission parameters Q The evolution law includes two obvious characteristics.

[0046] The first characteristic point: As the mechanical property curve of 316 steel is about to enter the yield stage, the acoustic emission parameters Q Then a clear peak appeared, and its value stabilized in the range of 0.1 to 0.2, and then gradually decreased. Q In the normalized curve of the cumulative value, it can be observed that the slope of the corresponding stage becomes larger, which usually means that at this particular stage, the parameter Q The value of becomes larger. This key parameter change can be used as a reliable evaluation index to assess the damage degree of 316 steel during the tensile process to reach the yield stage.

[0047] The second characteristic point: As the mechanical properties curve of 316 steel enters the crack propagation and fracture stage, the acoustic emission parameters Q It increases sharply, and its value ranges from 0.2 to 0.6, with a maximum value of 0.591. Q In the normalized curve of the cumulative value of , we can observe a sudden increase in the slope of the corresponding stage, which usually means that at this particular stage, the parameter Q The value of has significantly increased. This key parameter change can be used as a reliable evaluation indicator to assess whether the damage degree of 316 steel during the tensile process reaches the stage of crack extension or even fracture.

[0048] Therefore, based on the acoustic emission parameters Q The evolution law of AE can effectively characterize the damage degree of 316 steel during the tensile process. The key characteristic point of the material damage degree in this case is the acoustic emission parameter Q The significant peaks and sharp rises in parameter values.

Claims

1. A method for evaluating tensile damage of metal materials based on acoustic emission, characterized in that: The following steps are involved: S1, collecting acoustic emission signals, wherein the acoustic emission signals are obtained through an acoustic emission monitoring experiment during the stretching process of a metal material; S2, based on the acoustic emission signal, obtaining a peak factor of the acoustic emission signal, an information entropy of the acoustic emission signal, and a centroid frequency of the acoustic emission signal, multiplying the peak factor of the acoustic emission signal and the information entropy of the acoustic emission signal, dividing the product by the centroid frequency of the acoustic emission signal, and obtaining an acoustic emission parameter characterizing tensile damage; S3, evaluate the tensile damage degree of metal materials through the evolution law of acoustic emission parameters and the normalized curve of the cumulative value of acoustic emission parameters.

2. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S2, the calculation formula of the acoustic emission parameter characterizing the tensile damage is: （1） In the formula, Q To characterize the acoustic emission parameters of tensile damage, PF is the peak factor of the acoustic emission signal, H AE (V) is the information entropy of the acoustic emission signal, f c is the centroid frequency of the acoustic emission signal.

3. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S2, the information entropy of the acoustic emission signal is the ratio of the peak value of the acoustic emission signal to the root mean square value of the signal.

4. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 3, characterized in that: In S2, the peak factor calculation formula of the acoustic emission signal is: （2） In the formula, PF is the peak factor of the acoustic emission signal, P max is the peak value of the acoustic emission signal, RMS is the root mean square of the acoustic emission signal, X i The signal is i Sample values, N is the total number of samples.

5. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S2, the calculation formula of the information entropy of the acoustic emission signal is: （3） In the formula, H AE (V) is the information entropy of the acoustic emission signal; p(V i ) Represents every possible voltage value V i The probability in each group interval; b = 2, indicating that the dimension is bits.

6. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S2, the centroid frequency calculation formula of the acoustic emission signal is: （4） In the formula, f c is the acoustic emission centroid frequency, f i The signal is i frequency components, E(f i ) is the frequency corresponding to f i The energy value, N is the total number of frequency components.

7. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S3, when the acoustic emission parameter first rises and then falls, and the value of the entire process is between 0.1 and 0.2, the metal material reaches the yield stage during the stretching process.

8. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S3, when the acoustic emission parameter rises sharply, the normalized curve of the cumulative value of the acoustic emission parameter increases sharply, and the value of the acoustic emission parameter is greater than 0.2, cracks appear in the metal material during the stretching process.

9. The method for evaluating tensile damage of metal materials based on acoustic emission according to claim 1, characterized in that: In S1, the acoustic emission monitoring experiment is carried out by a metal material tensile damage monitoring system.

10. A metal material tensile damage evaluation device based on acoustic emission, characterized in that: include: A collection module, used for collecting acoustic emission signals, wherein the acoustic emission signals are obtained through an acoustic emission monitoring experiment during the stretching process of a metal material; A calculation module is used to obtain a peak factor of the acoustic emission signal, an information entropy of the acoustic emission signal, and a centroid frequency of the acoustic emission signal based on the acoustic emission signal, multiply the peak factor of the acoustic emission signal and the information entropy of the acoustic emission signal, divide the product by the centroid frequency of the acoustic emission signal, and obtain an acoustic emission parameter characterizing tensile damage; The evaluation module is used to evaluate the tensile damage degree of metal materials through the evolution law of acoustic emission parameters and the normalized curve of the cumulative value of acoustic emission parameters.

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