Material dynamic test data processing method and system, electronic equipment, and storage medium

Abstract

The present invention discloses a material dynamic test data processing method and system, electronic device, and storage medium. After acquiring an incident rod signal curve and a transmitted rod signal curve, the method first extracts an incident wave curve and a reflected wave curve from the incident rod signal curve, and extracts a transmitted wave curve from the transmitted rod signal curve. The method then automatically aligns the incident wave curve, the reflected wave curve, and the transmitted wave curve based on their pulse widths. After filtering and smoothing the incident wave curve, the reflected wave curve, and the transmitted wave curve are then automatically calculated to obtain an engineering stress-strain curve. Automatically aligning the pulse widths of the incident, reflected, and transmitted waves ensures data timing consistency, thereby ensuring the accuracy of the engineering stress-strain curve and accurately reflecting true dynamic mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of material dynamic testing, and in particular to a material dynamic testing data processing method and system, electronic equipment, and a computer-readable storage medium. Background Art

[0002] The mechanical properties of a material primarily refer to its properties under external forces, including strength, hardness, plasticity, and impact toughness. These performance indicators are of great significance for engineering structure design, material selection, and mechanical failure analysis. The true stress-strain curve of a material, which represents the relationship between stress and strain during a load, reflects the material's mechanical properties. Currently, there are three types of mechanical property testing: low-strain-rate quasi-static testing, medium-strain-rate dynamic testing, and high-strain-rate dynamic testing. Low-strain-rate quasi-static testing (strain rate <0.01 / s) is conducted using an electronic universal testing machine, while dynamic mechanical properties at medium strain rates (0.1-500 / s) are determined using a hydraulic servo testing machine. Dynamic mechanical properties at high strain rates (>1000 / s) are determined using a Hopkinson bar. Due to the different testing methods, the engineering stress-strain curve data for low-strain-rate quasi-static and medium-strain-rate dynamic testing can be directly measured, while the engineering stress-strain curve data for high-strain-rate dynamic testing is obtained using existing automated data processing programs. However, existing automated data processing programs are unable to automatically align the pulse widths of the incident, reflected, and transmitted waves, resulting in poor accuracy in stress-strain curves and difficulty accurately reflecting true dynamic mechanical properties. Furthermore, existing automated data processing programs are unable to automatically determine the validity of test data, failing to guarantee the accuracy and reliability of test results. Furthermore, existing automated data processing programs are unable to perform plastic flow constitutive model fitting, lacking fitting analysis for test data, making it impossible to apply test data to simulations. Summary of the Invention

[0003] The present invention provides a material dynamic test data processing method and system, electronic equipment, and computer-readable storage medium, which can automatically align the pulse widths of the incident wave, reflected wave, and transmitted wave, ensuring the consistency of the data timing, thereby ensuring the accuracy of the engineering stress-strain curve and accurately reflecting the actual dynamic mechanical properties.

[0004] According to one aspect of the present invention, a method for processing material dynamic test data is provided, comprising the following contents:

[0005] Obtaining the incident rod signal curve and the transmitted rod signal curve, extracting the incident wave curve and the reflected wave curve from the incident rod signal curve, extracting the transmitted wave curve from the transmitted rod signal curve, and automatically aligning the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width;

[0006] Filter and smooth the incident wave curve, reflected wave curve and transmitted wave curve;

[0007] The engineering stress-strain curve is calculated based on the incident wave curve, reflected wave curve and transmitted wave curve.

[0008] Furthermore, the process of extracting the incident wave curve and the reflected wave curve from the incident rod signal curve, extracting the transmitted wave curve from the transmitted rod signal curve, and automatically aligning the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width includes the following:

[0009] Find the extreme points of the incident wave and the reflected wave in the incident rod signal curve respectively, and use them as the characteristic points of the incident wave curve and the reflected wave curve respectively; find the extreme point of the transmitted wave in the transmitted rod signal curve, and use it as the characteristic point of the transmitted wave curve;

[0010] Based on the characteristic point of the incident wave curve, traverse forward in the incident rod signal curve, find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of this point, and use it as the starting point of the incident wave waveform; then traverse backward in the incident rod signal curve based on the characteristic point, find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all less than the measured value of this point, and use it as the ending point of the incident wave waveform, and determine the complete incident wave waveform curve based on the starting point and the ending point;

[0011] Based on the characteristic point of the reflected wave curve, the incident rod signal curve is traversed forward to find the data point whose first measurement value is less than the preset value and whose subsequent data points have all measured values ​​greater than the measurement value of the point, and the data point is used as the starting point of the reflected wave waveform. Based on the characteristic point, the incident rod signal curve is traversed backward to find the data point whose first measurement value is less than the preset value and whose subsequent data points have all measured values ​​less than the measurement value of the point, and the data point is used as the ending point of the reflected wave waveform. The complete reflected wave waveform curve is determined based on the starting point and the ending point.

[0012] Based on the characteristic points of the transmission wave curve, traverse forward in the transmission rod signal curve, find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of this point, and use it as the starting point of the transmission wave waveform. And determine the end point based on the same pulse width as the incident wave waveform, so as to determine the complete transmission wave waveform curve;

[0013] The starting points of the incident wave waveform curve, the reflected wave waveform curve, and the transmitted wave waveform curve are aligned, and the data with redundant time length in the reflected wave waveform curve are removed based on the principle of the same pulse width.

[0014] Furthermore, after obtaining the incident rod signal curve, the following contents are also included:

[0015] The test type is determined according to the incident wave signal value. If the incident wave signal value is positive, it is determined to be a tensile test. If the incident wave signal value is negative, it is determined to be a compression test.

[0016] Furthermore, after obtaining the incident rod signal curve, the following contents are also included:

[0017] Determine the validity of the incident rod signal and the transmitted rod signal.

[0018] Furthermore, the process of determining the validity of the incident rod signal includes the following:

[0019] Obtain the theoretical incident rod signal curve, calculate the ratio of the difference between the maximum value of the measured incident rod signal and the maximum value of the theoretical incident rod signal to the maximum value of the theoretical incident rod signal, if the ratio is greater than the preset threshold, then the incident rod signal is determined to be invalid, otherwise the incident rod signal is determined to be valid; calculate the correlation between the measured incident rod signal curve and the theoretical incident rod signal curve, if the correlation between the two is greater than the preset threshold, then the incident rod signal is determined to be valid, otherwise the incident rod signal is determined to be invalid.

[0020] Furthermore, it also includes the following:

[0021] The calibration signal curve of the dynamic test calibration sensor is obtained, and the incident rod signal curve and the transmitted rod signal curve are compared with the calibration signal curve respectively. The validity of the incident rod strain gauge signal and the transmitted rod strain gauge signal are judged according to the comparison results.

[0022] Furthermore, it also includes the following:

[0023] The true stress-plastic strain curve is converted based on the engineering stress-strain curve, and then the constitutive model is used to perform fitting and extrapolation analysis based on the true stress-plastic strain curve to obtain the plastic flow curve.

[0024] In addition, the present invention also provides a material dynamic test data processing system, comprising:

[0025] The waveform curve automatic alignment module is used to obtain the incident rod signal curve and the transmitted rod signal curve, extract the incident wave curve and the reflected wave curve from the incident rod signal curve, extract the transmitted wave curve from the transmitted rod signal curve, and automatically align the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width;

[0026] Data filtering and smoothing processing module, used for filtering and smoothing the incident wave curve, reflected wave curve and transmitted wave curve;

[0027] The engineering stress-strain curve generation module is used to calculate the engineering stress-strain curve based on the incident wave curve, the reflected wave curve and the transmitted wave curve.

[0028] In addition, the present invention also provides an electronic device, including a processor and a memory, wherein the memory stores a computer program, and the processor is configured to execute the steps of the above method by calling the computer program stored in the memory.

[0029] In addition, the present invention also provides a computer-readable storage medium for storing a computer program for processing material dynamic test data, wherein the computer program executes the steps of the above-mentioned method when running on a computer.

[0030] The present invention has the following beneficial effects:

[0031] The present invention's material dynamic test data processing method, after acquiring the incident and transmitted signal curves, first extracts the incident and reflected wave curves from the incident signal curve, and extracts the transmitted wave curve from the transmitted signal curve. The method then automatically aligns the incident, reflected, and transmitted wave curves based on their pulse widths. After filtering and smoothing the incident, reflected, and transmitted wave curves, the engineering stress-strain curve is automatically calculated. Automatically aligning the pulse widths of the incident, reflected, and transmitted waves ensures data timing consistency, thereby guaranteeing the accuracy of the engineering stress-strain curves and accurately reflecting true dynamic mechanical properties.

[0032] In addition, the material dynamic test data processing system of the present invention also has the above advantages.

[0033] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0035] Figure 1 It is a flow chart of a material dynamic test data processing method according to a preferred embodiment of the present application;

[0036] Figure 2Schematic diagram of a high strain rate dynamic test in which a specimen is mounted on a Hopkinson bar in a preferred embodiment of the present application;

[0037] Figure 3 yes Figure 1 Schematic diagram of the sub-process of step S1;

[0038] Figure 4 Schematic diagram of finding the extreme points of the incident wave curve, the reflected wave curve, and the transmitted wave curve in a preferred embodiment of the present application;

[0039] Figure 5 Schematic diagram of finding the starting point and ending point of the incident wave curve, the reflected wave curve, and the transmitted wave curve in a preferred embodiment of the present application;

[0040] Figure 6 is a schematic diagram of automatically aligning the incident wave curve, the reflected wave curve, and the transmitted wave curve in a preferred embodiment of the present application;

[0041] Figure 7 is a schematic diagram of an engineering stress-strain curve generated in a preferred embodiment of the present application;

[0042] Figure 8 This is a schematic diagram of data signals for a tensile test in a preferred embodiment of the present application;

[0043] Figure 9 This is a schematic diagram of data signals for a compression test in a preferred embodiment of the present application;

[0044] Figure 10 is a schematic diagram of an incident rod signal curve and a theoretical incident rod signal curve measured during a tensile test in a preferred embodiment of the present application;

[0045] Figure 11 is a schematic diagram showing that the transmission rod signal curve in the preferred embodiment of the present application does not return to zero;

[0046] Figure 12 This is a schematic diagram of the installation of a dynamic test calibration sensor in a preferred embodiment of the present application;

[0047] Figure 13 Schematic diagram of force curves of the incident rod strain gauge signal, the piezoelectric crystal force signal, the calibration strain gauge signal, and the transmission rod strain gauge signal obtained when performing strain gauge calibration in a preferred embodiment of the present application;

[0048] Figure 14 1 is a schematic diagram of the alignment of the force curves of the incident rod strain gauge signal, the piezoelectric crystal force signal, the calibration strain gauge signal, and the transmission rod strain gauge signal obtained during calibration in a preferred embodiment of the present application;

[0049] Figure 15This is another flow chart of the material dynamic test data processing method according to the preferred embodiment of the present application;

[0050] Figure 16 Schematic diagram of plastic flow curves obtained by fitting simulation using different constitutive models in a preferred embodiment of the present application;

[0051] Figure 17 It is a schematic diagram of the module structure of a material dynamic test data processing system according to another embodiment of the present application. DETAILED DESCRIPTION

[0052] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] Reference Figure 1 The preferred embodiment of the present application provides a material dynamic test data processing method, including the following contents:

[0054] Step S1: Obtain an incident rod signal curve and a transmitted rod signal curve, extract an incident wave curve and a reflected wave curve from the incident rod signal curve, extract a transmitted wave curve from the transmitted rod signal curve, and automatically align the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width;

[0055] Step S2: filtering and smoothing the incident wave curve, the reflected wave curve and the transmitted wave curve;

[0056] Step S3: Calculate the engineering stress-strain curve based on the incident wave curve, the reflected wave curve, and the transmitted wave curve.

[0057] It can be understood that the material dynamic test data processing method of this embodiment, after obtaining the incident and transmitted rod signal curves, first extracts the incident wave curve and reflected wave curve from the incident wave curve, and extracts the transmitted wave curve from the transmitted rod signal curve. The incident, reflected, and transmitted wave curves are then automatically aligned based on their pulse widths. After filtering and smoothing the incident, reflected, and transmitted wave curves, the engineering stress-strain curve is automatically calculated. Automatic alignment of the pulse widths of the incident, reflected, and transmitted waves ensures data timing consistency, thereby guaranteeing the accuracy of the engineering stress-strain curves and accurately reflecting true dynamic mechanical properties.

[0058] It is understandable that Figure 2As shown, after the specimen is mounted on the Hopkinson bar, a high strain rate dynamic test can be performed. The test data that can be obtained by the ultra-dynamic strain gauge and the data acquisition system include time, incident bar signal, and transmitted bar signal. The incident bar signal is the strain gauge signal on the incident bar, and the transmitted bar signal is the strain gauge signal on the transmitted bar. In step S1, the collected test data is obtained from the data acquisition system to generate the incident bar signal curve and the transmitted bar signal curve. When performing a high strain rate dynamic test, after the incident pulse signal is input into the incident bar, the strain gauge on the incident bar will collect the first incident wave signal. When the incident pulse signal propagates backward to the specimen, it will generate the first reflected wave signal and the first transmitted wave signal. The first reflected wave signal will propagate forward along the incident bar, while the first transmitted wave signal will propagate backward along the transmitted bar. Subsequently, the first reflected wave signal will be reflected again to form a second incident wave signal, which will propagate backward again, and this reciprocating process will continue. During this reciprocating process, the wave will continue to attenuate. Therefore, it is necessary to accurately extract the first incident wave signal and the first reflected wave signal from the incident rod signal curve, namely the incident wave curve and the reflected wave curve, and accurately extract the first transmitted wave signal from the transmitted rod signal curve, namely the transmitted wave curve. Then, based on the pulse width, the incident wave waveform curve, the reflected wave waveform curve, and the transmitted wave waveform curve are automatically aligned to facilitate the subsequent accurate calculation of the engineering stress-strain curve.

[0059] Among them, Figure 3 As shown in FIG, the incident wave curve and the reflected wave curve are extracted from the incident rod signal curve, the transmitted wave curve is extracted from the transmitted rod signal curve, and the incident wave curve, the reflected wave curve, and the transmitted wave curve are automatically aligned based on the pulse width. The process includes the following:

[0060] Step S11: Find the extreme points of the incident wave and the reflected wave in the incident rod signal curve, and use them as the characteristic points of the incident wave curve and the reflected wave curve respectively; find the extreme point of the transmitted wave in the transmitted rod signal curve, and use it as the characteristic point of the transmitted wave curve;

[0061] Step S12: based on the characteristic point of the incident wave curve, traverse forward in the incident rod signal curve to find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of this point, and use this data point as the starting point of the incident wave waveform; then, based on the characteristic point, traverse backward in the incident rod signal curve to find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all less than the measured value of this point, and use this data point as the ending point of the incident wave waveform; and determine the complete incident wave waveform curve based on the starting point and the ending point;

[0062] Step S13: based on the characteristic point of the reflected wave curve, traverse forward in the incident rod signal curve to find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of this point, and use this data point as the starting point of the reflected wave waveform; then, based on the characteristic point, traverse backward in the incident rod signal curve to find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all less than the measured value of this point, and use this data point as the ending point of the reflected wave waveform; and determine the complete reflected wave waveform curve based on the starting point and the ending point;

[0063] Step S14: based on the characteristic points of the transmission wave curve, traverse forward in the transmission rod signal curve, find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of this point, use it as the starting point of the transmission wave waveform, and determine the end point based on the same pulse width as the incident wave waveform, thereby determining the complete transmission wave waveform curve;

[0064] Step S15: aligning the starting points of the incident wave waveform curve, the reflected wave waveform curve, and the transmitted wave waveform curve, and removing redundant time-length data in the reflected wave waveform curve based on the principle of the same pulse width.

[0065] Specifically, the present invention first finds the extreme points of the incident wave and the reflected wave in the incident rod signal curve. Since the wave is constantly attenuating, the extreme points can be used as the characteristic points of the first incident wave and the first reflected wave, that is, the characteristic points of the incident wave curve and the reflected wave curve, such as Figure 4 As shown, the minimum value in the incident rod signal curve is the characteristic point of the first incident wave waveform curve, and the maximum value is the characteristic point of the first reflected wave waveform curve.

[0066] Then, based on the characteristic point of the incident wave waveform curve, traverse forward in the incident rod signal curve to find the first data point whose measurement value is less than 0.05V and the measurement values ​​of subsequent data points are all greater than the measurement value of this point, and take the first data point that meets this condition as the starting point of the incident wave waveform. Based on the characteristic point, traverse backward in the incident rod signal curve to find the first data point whose measurement value is less than 0.05V and the measurement values ​​of subsequent data points are all less than the measurement value of this point, and take the first data point that meets this condition as the end point of the incident wave waveform, so that the complete incident wave waveform curve can be determined based on the starting point and the end point. Similarly, based on the characteristic points of the reflected wave curve, we traverse forward in the incident rod signal curve to find the first data point with a measurement value less than 0.05V and the measurement values ​​of subsequent data points are all greater than the measurement value at this point. This data point is used as the starting point of the reflected wave waveform. Based on this characteristic point, we traverse backward in the incident rod signal curve to find the first data point with a measurement value less than 0.05V and the measurement values ​​of subsequent data points are all less than the measurement value at this point. This data point is used as the ending point of the reflected wave waveform. The complete reflected wave waveform curve is determined based on the starting and ending points. It can be understood that due to the noise in the signal collected by the strain gauge, the measurement value of the starting point of the wave will not be zero.

[0067] Next, based on the characteristic points of the transmission wave curve, traverse forward in the transmission rod signal curve to find the first data point whose measured value is less than 0.05V and the measured values ​​of subsequent data points are all greater than the measured value of this point, and use it as the starting point of the transmission wave waveform. Since the transmission wave passes the extreme point, it means that the specimen has broken or the waveform time has ended. In order to ensure the accuracy of the transmission wave data acquisition, the present invention determines the end point of the transmission wave waveform based on the same pulse width as the incident wave waveform, that is, the pulse width of the transmission wave waveform curve must be the same as the pulse width of the incident wave waveform curve, thereby determining the complete transmission wave waveform curve. Among them, the position diagram of the starting point and end point of the incident wave waveform curve, the reflected wave waveform curve and the transmission wave waveform curve is shown as follows: Figure 5 shown.

[0068] Then, align the starting points of the incident wave waveform curve, the reflected wave waveform curve, and the transmitted wave waveform curve, and remove the redundant time data in the reflected wave waveform curve based on the principle of the same pulse width. Since the end point of the transmitted wave waveform curve is determined based on the same principle as the incident wave waveform curve pulse width, there is no need to remove the redundant time data points, and the incident wave waveform curve, the reflected wave waveform curve, and the transmitted wave waveform curve can be automatically aligned, as shown in the following example: Figure 6 The strain gauge measures voltage values, which need to be converted into strain values. The specific conversion process belongs to the existing technology and will not be described here.

[0069] It can be understood that the present invention uses extreme points as characteristic points of the first incident wave, reflected wave and transmitted wave, and based on the characteristic points, respectively searches for the starting point and ending point of the incident wave waveform curve, the reflected wave waveform curve, and the starting point of the transmitted wave waveform curve, and determines the ending point of the transmitted wave waveform curve based on the principle of the same pulse width. The incident wave waveform curve, the reflected wave waveform curve and the transmitted wave waveform curve can be automatically aligned based on the pulse width, thereby ensuring the timing consistency of the three waveform curves, thereby ensuring the accuracy of the engineering stress-strain curve, and accurately reflecting the true dynamic mechanical properties.

[0070] It can be understood that in step S2, the signal collected by the HPKS (Hopkinson bar) data acquisition system is superimposed with a noise signal, and the noise signal contains periodic interference signals such as the 50Hz power frequency and its octaves. Therefore, the three aligned waveform curves need to be filtered. Digital filtering is a processing method that selects a part of the signal of interest from the collected discrete signal through mathematical operations. Its main functions are to filter out noise or false components in the test signal, improve the signal-to-noise ratio, smooth analysis data, suppress interference signals, separate frequency components, etc. Optionally, the present invention uses an infinite length IIR impulse response digital filter (Infinite Impulse Response Digital Filter) for low-pass filtering. The filtering expression of the IIR filter can be defined as a differential equation: ,in, and represent the input and output time domain signal sequences respectively, and are all filter coefficients, N is the order of the IIR filter, or the number of poles of the filter system transfer function, and M is the number of zeros of the filter system transfer function. Its transfer function can be expressed as: , H() represents the transfer function. Commonly used prototype generation functions of analog low-pass filters include Butterworth filter prototype, Chebyshev type I and type II filter prototypes, elliptic filter prototype, Bessel filter prototype, etc. Since the characteristic of Butterworth filter is that it has the flattest amplitude characteristic in the passband, the low-pass filtering of the present invention preferably adopts Butterworth filter, and the MATLAB signal processing toolbox provides a function for directly designing Butterworth filter, which greatly facilitates the design of general filters. Function butter is the design function of Butterworth filter, and its input parameters mainly include the order n of the filter, the normalized natural cutoff frequency W n , the output is the filter coefficient; the function buttord is the Butterworth filter order selection function, which can calculate the order and normalized natural cutoff frequency required for the filter design function. The input parameters of this function are the passband and stopband cutoff frequencies W p and Ws , passband and stopband ripple coefficient R p and R s ; The cutoff frequency is the normalized frequency, and the frequency range is from 0 to 1, where 1 corresponds to the folding frequency, which is half the sampling frequency.

[0071] In addition, considering that the noise signal in the dynamic signal collected by the HPKS test machine also includes irregular random interference signals, the frequency band of this random interference signal is relatively wide, and sometimes the high-frequency component accounts for a relatively large proportion, which cannot be removed by filtering, resulting in many burrs on the curve drawn by the collected discrete data, which is very rough. In addition, sometimes the test system is subject to certain unexpected interferences, causing the sampling signals of individual measuring points to produce trend items that deviate greatly from the baseline and have irregular shapes. Therefore, the present invention also smoothes the waveform curve after filtering, wherein there are two ways of smoothing: a) removing abnormal areas and replacing them with interpolation data from other areas, and the interpolation methods include piecewise linear interpolation, cubic interpolation and cubic spline interpolation, etc.; b) using the sliding average method to perform multiple data smoothing processes on the measurement signal to remove irregular trend items, wherein the expression of the sliding average method is: , where x represents the sampled data, y is the smoothed data, and N is the sliding average order. The averaged data can be averaged again. The larger the number of sliding averages, the smoother the curve.

[0072] It can be understood that in step S3, after filtering and smoothing the data of the three waveform curves, the one-wave method or the three-wave method can be selected to automatically calculate the engineering stress-strain curve, for example Figure 7 As shown. Among them, the one-wave method and the three-wave method are both existing algorithms. The specific engineering stress-strain curve calculation process will not be described here. For example, the calculation formula of the one-wave method is: ;

[0073] ;

[0074] in, represents the engineering strain, represents the engineering strain rate, represents the engineering stress, represents the reflected strain, represents the transmission strain, represents the incident strain, C0 represents the wave velocity, l s represents the length of the specimen, t represents the duration of the stress wave, A represents the cross-sectional area of ​​the transmission rod, and A s represents the cross-sectional area of ​​the specimen, and E represents the elastic modulus.

[0075] In addition, in step S3, according to the GB / T228.1 standard, the present invention also extracts the engineering stress data segment and engineering strain data segment of the engineering stress-strain curve with a strain of 0.0005~0.0025, obtains a series of numerical values, and performs linear fitting to obtain the slope of the linear segment. The slope is the dynamic elastic modulus of the specimen, and the dynamic elastic modulus is compared with the static elastic modulus. If the difference between the two exceeds a preset value (for example, 10%), the engineering stress-strain curve is determined to be invalid. If the difference between the two does not exceed the preset value, the engineering stress-strain curve is determined to be valid. At the same time, the average engineering strain rate during the test process is analyzed and calculated. If the deviation between the average engineering strain rate and the target engineering strain rate is not greater than a preset value (for example, 30%), it is determined to be a true strain rate result. If the deviation between the two is greater than the preset value, the test is determined to be invalid. Therefore, the present invention can also judge the validity of the calculated engineering stress-strain curve, further ensuring the accuracy and reliability of the test results.

[0076] Optionally, in step S1, after obtaining the incident rod signal curve, the following steps are further included:

[0077] The test type is determined according to the incident wave signal value. If the incident wave signal value is positive, it is determined to be a tensile test. If the incident wave signal value is negative, it is determined to be a compression test.

[0078] Specifically, after obtaining the incident rod signal curve, since the incident rod signal includes the incident wave signal and the reflected wave signal, and the reflected wave signal is after the incident wave signal, the test type can be judged according to the incident wave signal value. If the incident wave signal value is positive, it means that the incident rod has been stretched and deformed, such as Figure 8 As shown, it is determined to be a tensile test. If the incident wave signal is negative, it means that the incident rod has been compressed and deformed, as shown in Figure 9 Therefore, the present invention can quickly and intuitively determine the test type based on the incident wave signal value.

[0079] Optionally, step S1 further includes the following:

[0080] Determine the validity of the incident rod signal and the transmitted rod signal.

[0081] The process of judging the validity of the incident rod signal includes the following:

[0082] Obtain the theoretical incident rod signal curve, calculate the ratio of the difference between the maximum value of the measured incident rod signal and the maximum value of the theoretical incident rod signal to the maximum value of the theoretical incident rod signal, if the ratio is greater than the preset threshold, then the incident rod signal is determined to be invalid, otherwise the incident rod signal is determined to be valid; calculate the correlation between the measured incident rod signal curve and the theoretical incident rod signal curve, if the correlation between the two is greater than the preset threshold, then the incident rod signal is determined to be valid, otherwise the incident rod signal is determined to be invalid.

[0083] Specifically, the theoretical incident rod signal curve is calculated based on the impact rod length and impact velocity of the Hopkinson rod, such as Figure 10 The blue line in the figure represents the incident rod signal curve obtained by experimental measurement. Then, the ratio between the difference between the maximum value of the measured incident rod signal and the maximum value of the theoretical incident rod signal and the maximum value of the theoretical incident rod signal is calculated. The calculation formula is: , Indicates the maximum value of the incident rod signal. Indicates the maximum theoretical incident rod signal, Represents a ratio, if If it exceeds 10%, the incident rod signal is considered invalid. If the correlation does not exceed 10%, the incident rod signal is determined to be valid. In addition, the correlation between the measured incident rod signal curve and the theoretical incident rod signal curve is also calculated. Specifically, the correlation can be calculated using the existing cosine similarity algorithm or correlation coefficient algorithm. If the correlation is greater than 0.9, the incident rod signal is determined to be valid. If the correlation is not greater than 0.9, the incident rod signal is determined to be invalid. Therefore, the waveform of the incident rod signal curve needs to meet the above two conditions at the same time to determine that the incident rod signal is valid. Otherwise, the incident rod signal is determined to be invalid. If the incident rod signal is determined to be invalid, the test system needs to be re-tested, including the alignment of the impact rod, incident rod and transmission rod, optimization of the shaping sheet, strain gauge inspection, etc., and the static electricity of the measurement system needs to be eliminated.

[0084] In addition, the process of judging the validity of the transmission rod signal includes the following:

[0085] In the initial stage of the pre-experiment, that is, when the test piece is not installed for testing, the transmission rod is used as the incident rod, and the impact rod is used to impact the transmission rod. The impact waveform (i.e., the incident waveform) and the reflected waveform collected on the transmission rod are measured. If the difference between the first impact waveform and the first reflected waveform does not exceed 2%, for example, the correlation between the impact waveform curve and the reflected waveform curve exceeds 98%, then the transmission rod signal is determined to be valid. Otherwise, the transmission rod signal is determined to be invalid. In addition, it is determined whether the collected transmission rod signal curve eventually returns to zero, for example, Figure 11 As shown in the figure, if the transmission rod signal curve does not return to zero after the test, it is determined that there is a problem with the transmission rod signal and the acquisition system such as the strain gauge needs to be rechecked.

[0086] It can be understood that the present invention can also perform validity judgment on the incident rod signal and the transmitted rod signal, thereby ensuring the accuracy and reliability of the test data.

[0087] Optionally, after obtaining the incident rod signal curve and the transmitted rod signal curve in step S1, the following steps may also be included:

[0088] The calibration signal curve of the dynamic test calibration sensor is obtained, and the incident rod signal curve and the transmitted rod signal curve are compared with the calibration signal curve respectively. The validity of the incident rod strain gauge signal and the transmitted rod strain gauge signal are judged according to the comparison results.

[0089] Specifically, before the test, in order to ensure the reliability of the strain gauge data collected, the incident rod strain gauge and the transmission rod strain gauge need to be calibrated. The present invention uses a dynamic test calibration sensor for calibration. The dynamic test calibration sensor consists of a piezoelectric crystal force sensor and a strain gauge connected in series, and its two ends are connected to the incident rod and the transmission rod by threads, such as Figure 12 As shown. Among them, the piezoelectric crystal force sensor is an element that uses the piezoelectric effect to realize the sensing function. It has the forward piezoelectric effect and the reverse piezoelectric effect. The forward piezoelectric effect is: when mechanical pressure or stress is applied to the piezoelectric crystal, the crystal will generate an electric charge. This is because the distribution of positive and negative charges inside the crystal changes under the action of pressure, thereby forming a charge on the surface of the crystal and generating a voltage signal; the reverse piezoelectric effect is: when an electric field is applied to the piezoelectric crystal, the crystal will deform. This deformation is due to the electric field causing the distribution of positive and negative charges inside the crystal to change, resulting in a slight change in the size of the crystal. Typical piezoelectric crystal force sensors are made of piezoelectric materials, such as quartz, strontium tungstate and other crystals. These materials can generate measurable charge or voltage signals when external force or electric field is applied. Piezoelectric crystal force sensors can generate a large electrical signal response to tiny pressure or strain, with a fast response speed, which can meet the requirements of high strain rate dynamic performance testing. When the bullet hits the incident rod, four signals can be collected, namely: the incident rod strain gauge signal, the piezoelectric crystal force value signal, the calibration strain gauge signal, and the transmission rod strain gauge signal. The four signal curves obtained after converting the strain gauge signal into the force value signal are as follows: Figure 13 Then align the time starting points of the four signal curves, as shown in Figure 14 As shown, a comparative analysis is performed. If the following conditions are met, the incident rod strain gauge signal and the transmitted rod strain gauge signal are determined to be valid:

[0090] 1) The correlation between the incident rod strain gauge signal, the transmitted rod strain gauge signal, the piezoelectric crystal force signal, and the calibration strain gauge signal is not less than a preset value, such as 0.9;

[0091] 2) The platform value deviation does not exceed 5%;

[0092] 3) The total pulse width deviation does not exceed 5%.

[0093] If the incident rod strain gauge signal and the transmitted rod strain gauge signal do not meet the above three conditions at the same time, they are judged to be invalid, and the pasting of the strain gauge needs to be checked to ensure the accuracy and reliability of the strain gauge acquisition signal.

[0094] In addition, the force signal of the piezoelectric crystal is basically consistent with the force signal of the calibration strain gauge, so the calibration strain gauge can be omitted, that is, the dynamic test calibration sensor only uses the piezoelectric crystal force sensor.

[0095] Optionally, the present invention can also perform dynamic sensitivity measurement on the incident rod strain gauge and the transmission rod strain gauge according to the piezoelectric crystal force value signal, specifically based on the following formula: , where a represents the dynamic sensitivity, F load represents the force value of the piezoelectric crystal force sensor, A represents the cross-sectional area of ​​the incident rod or the transmitted rod, E represents the elastic modulus of the incident rod or the transmitted rod, and f represents the gain factor of the incident rod strain gauge or the transmitted rod strain gauge. It is understood that, typically, the sensitivity coefficient of a strain gauge is obtained by testing under low-speed static conditions, and the sensitivity coefficient under high-speed dynamic conditions will be different. However, the present invention can accurately obtain the sensitivity coefficient of a strain gauge under high-speed dynamic conditions.

[0096] Alternatively, as Figure 15 As shown, the material dynamic test data processing method also includes the following contents:

[0097] Step S4: The true stress-plastic strain curve is converted based on the engineering stress-strain curve, and then the constitutive model is used to perform fitting and extrapolation analysis based on the true stress-plastic strain curve to obtain the plastic flow curve.

[0098] Specifically, the true stress-plastic strain curve is first converted based on the engineering stress-strain curve. The conversion formula is: ,in, represents the true strain, represents the engineering strain, represents the true stress, represents the engineering stress, Represents plastic strain, and E represents elastic modulus. After obtaining the true stress-plastic strain curve, the data after the necking point is eliminated. The data before necking are used by programming to fit different simulation models, such as JC, swfit, Ludwick, Voce, etc., and multiple strain rate curves of the same material are uniformly fitted and extrapolated to a strain of 1. Among them, the same strain rate is generally taken from the middle curve of the three test curves, and the number of curve points is 100, such as Figure 16After fitting the extrapolated plastic flow curve, the extrapolated curve can be directly applied to simulation software such as LS-DYNA and AQAQUS to simulate the dynamic mechanical properties of the material, thus improving the usability of HPKS test data.

[0099] In addition, if Figure 17 As shown, another embodiment of the present invention further provides a material dynamic test data processing system, preferably using the material dynamic test data processing method as described above, including:

[0100] The waveform curve automatic alignment module is used to obtain the incident rod signal curve and the transmitted rod signal curve, extract the incident wave curve and the reflected wave curve from the incident rod signal curve, extract the transmitted wave curve from the transmitted rod signal curve, and automatically align the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width;

[0101] Data filtering and smoothing processing module, used for filtering and smoothing the incident wave curve, reflected wave curve and transmitted wave curve;

[0102] The engineering stress-strain curve generation module is used to calculate the engineering stress-strain curve based on the incident wave curve, the reflected wave curve and the transmitted wave curve.

[0103] It can be understood that after acquiring the incident and transmitted rod signal curves, the material dynamic test data processing system of this embodiment first extracts the incident wave curve and the reflected wave curve from the incident wave curve, and extracts the transmitted wave curve from the transmitted rod signal curve. The system then automatically aligns the incident, reflected, and transmitted wave curves based on their pulse widths. After filtering and smoothing the incident, reflected, and transmitted wave curves, the system automatically calculates the engineering stress-strain curve. Automatically aligning the pulse widths of the incident, reflected, and transmitted waves ensures data timing consistency, thereby guaranteeing the accuracy of the engineering stress-strain curve and accurately reflecting true dynamic mechanical properties.

[0104] In addition, the material dynamic test data processing system also includes:

[0105] The fitting and extrapolation analysis module is used to convert the true stress-plastic strain curve based on the engineering stress-strain curve, and then use the constitutive model to perform fitting and extrapolation analysis based on the true stress-plastic strain curve to obtain the plastic flow curve.

[0106] In addition, another embodiment of the present invention further provides an electronic device, including a processor and a memory, wherein the memory stores a computer program, and the processor is configured to execute the steps of the above method by calling the computer program stored in the memory.

[0107] In addition, another embodiment of the present invention further provides a computer-readable storage medium for storing a computer program for processing material dynamic test data, wherein the computer program executes the steps of the above-described method when running on a computer.

[0108] Common forms of computer-readable storage media include floppy disks, flexible disks, hard disks, magnetic tape, any other magnetic media, CD-ROMs, any other optical media, punch cards, paper tape, any other physical medium with a pattern of holes, random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), flash-EPROM, any other memory chip or cartridge, or any other medium that can be read by a computer. Instructions can further be transmitted or received via a transmission medium. The term transmission medium may include any tangible or intangible medium that can be used to store, encode, or carry instructions for execution by a machine, including digital or analog communication signals or other intangible media that facilitate communication of such instructions. Transmission media include coaxial cables, copper wire, and fiber optics, including the wires of a bus used to transmit computer data signals.

[0109] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a fully hardware embodiment, a fully software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present application may be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0110] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1A device that provides the functions specified in a block or multiple blocks.

[0111] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0112] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0113] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0114] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

[0115] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A material dynamic test data processing method, characterized in that: Includes the following: Obtaining the incident rod signal curve and the transmitted rod signal curve, extracting the incident wave curve and the reflected wave curve from the incident rod signal curve, extracting the transmitted wave curve from the transmitted rod signal curve, and automatically aligning the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width; Filter and smooth the incident wave curve, reflected wave curve and transmitted wave curve; The engineering stress-strain curve is calculated based on the incident wave curve, reflected wave curve and transmitted wave curve; The process of extracting the incident wave curve and the reflected wave curve from the incident rod signal curve, extracting the transmitted wave curve from the transmitted rod signal curve, and automatically aligning the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width includes the following: Find the extreme points of the incident wave and the reflected wave in the incident rod signal curve respectively, and use them as the characteristic points of the first incident wave curve and the first reflected wave curve respectively; find the extreme point of the transmitted wave in the transmitted rod signal curve, and use it as the characteristic point of the first transmitted wave curve; Based on the characteristic point of the incident wave curve or the reflected wave curve, traverse forward in the incident rod signal curve to find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of the point, and use it as the starting point of the incident wave waveform or the reflected wave waveform; then traverse backward based on the characteristic point to find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all less than the measured value of the point, and use it as the ending point of the incident wave waveform or the reflected wave waveform, and determine the complete incident wave waveform curve or the reflected wave waveform based on the starting point and the ending point; Based on the characteristic points of the transmission wave curve, traverse forward in the transmission rod signal curve, find the first data point whose measured value is less than the preset value and the measured values ​​of subsequent data points are all greater than the measured value of this point, and use it as the starting point of the transmission wave waveform. And determine the end point based on the same pulse width as the incident wave waveform, so as to determine the complete transmission wave waveform curve; Align the starting points of the incident wave waveform curve, the reflected wave waveform curve, and the transmitted wave waveform curve, and remove the redundant time length data in the reflected wave waveform curve based on the principle of the same pulse width; Also included: Obtain the calibration signal curve of the dynamic test calibration sensor, compare the incident rod signal curve and the transmitted rod signal curve with the calibration signal curve respectively, and judge the validity of the incident rod strain gauge signal and the transmitted rod strain gauge signal respectively based on the comparison results. The dynamic test calibration sensor is a piezoelectric crystal force sensor, and its two ends are connected to the incident rod and the transmitted rod by threads. If the following conditions are met, the incident rod strain gauge signal and the transmitted rod strain gauge signal are judged to be valid: 1) The correlation between the incident rod strain gauge signal, the transmitted rod strain gauge signal and the piezoelectric crystal force signal is not less than the preset value; 2) The platform value deviation does not exceed 5%; 3) The total pulse width deviation does not exceed 5%; After obtaining the incident rod signal curve, the following steps are also included: judging the validity of the incident rod signal and the transmitted rod signal; The process of judging the validity of the incident rod signal includes the following: Obtaining a theoretical incident rod signal curve, calculating a ratio between a difference between a maximum value of the measured incident rod signal and a maximum value of the theoretical incident rod signal and the maximum value of the theoretical incident rod signal, and calculating a correlation between the measured incident rod signal curve and the theoretical incident rod signal curve; if the ratio is less than or equal to a preset threshold and the correlation between the two curves is greater than the preset threshold, determining that the incident rod signal is valid; otherwise, determining that the incident rod signal is invalid; The process of judging the validity of the transmission rod signal includes the following: When the test piece is not installed, the transmission rod is used as the incident rod for testing, and the impact rod is used to impact the transmission rod. The first impact waveform and reflection waveform collected on the transmission rod are measured. If the difference between the first impact waveform and the first reflection waveform does not exceed 2%, and the collected transmission rod signal curve finally returns to zero, the transmission rod signal is determined to be valid, otherwise the transmission rod signal is determined to be invalid.

2. The material dynamic test data processing method according to claim 1, characterized in that: After obtaining the incident rod signal curve, the following contents are also included: The test type is determined according to the incident wave signal value. If the incident wave signal value is positive, it is determined to be a tensile test. If the incident wave signal value is negative, it is determined to be a compression test.

3. The material dynamic test data processing method according to claim 1, characterized in that: Also included: The true stress-plastic strain curve is converted based on the engineering stress-strain curve, and then the constitutive model is used to perform fitting and extrapolation analysis based on the true stress-plastic strain curve to obtain the plastic flow curve.

4. A material dynamic test data processing system, using the material dynamic test data processing method according to any one of claims 1 to 3, characterized in that: include: The waveform curve automatic alignment module is used to obtain the incident rod signal curve and the transmitted rod signal curve, extract the incident wave curve and the reflected wave curve from the incident rod signal curve, extract the transmitted wave curve from the transmitted rod signal curve, and automatically align the incident wave curve, the reflected wave curve, and the transmitted wave curve based on the pulse width; Data filtering and smoothing processing module, used for filtering and smoothing the incident wave curve, reflected wave curve and transmitted wave curve; The engineering stress-strain curve generation module is used to calculate the engineering stress-strain curve based on the incident wave curve, the reflected wave curve and the transmitted wave curve.

5. An electronic device, characterized in that: The method comprises a processor and a memory, wherein a computer program is stored in the memory, and the processor is configured to execute the steps of the method according to any one of claims 1 to 3 by calling the computer program stored in the memory.

6. A computer-readable storage medium for storing a computer program for processing material dynamic test data, characterized in that: When the computer program is run on a computer, the steps of the method according to any one of claims 1 to 3 are executed.

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