Monitoring system and method of automobile fastener vibration test equipment

Abstract

The invention discloses a monitoring system and method for automobile fastener vibration test equipment, and relates to the technical field of equipment monitoring, and the method comprises the steps: calculating a strain value of an automobile fastener monitoring point through employing a wavelength shift data stream, drawing a strain thermodynamic diagram, analyzing a local strain gradient, setting a strain gradient threshold value, and carrying out the measurement of the strain value. When the local strain gradient exceeds a strain gradient threshold value, a sound-light alarm signal is sent out and transmitted to the vibration table, a frequency reduction protection mechanism of the vibration table is activated, and the operation state of the vibration table is obtained; a vibration signal is collected, a vibration spectrogram is generated, an equivalent impedance network model is constructed, the vibration spectrogram is analyzed, and a parasitic resonance frequency point is identified. According to the invention, the risk of equipment damage caused by inaccurate suppression of the resonant frequency is effectively avoided, the accuracy of parasitic resonant frequency point identification is improved, the problem of inaccurate suppression of the resonant frequency is solved, and unnecessary energy consumption and mechanical damage are also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of equipment monitoring, and particularly to a monitoring system and method for an automotive fastener vibration test equipment. Background Art

[0002] With the application of lightweight and high-strength materials in the automotive industry and the operating requirements under complex working conditions, the importance of vibration testing technology in the performance evaluation of fasteners has become increasingly prominent. Conventional vibration testing mainly relies on acceleration sensors and strain gauges to analyze the dynamic response of fasteners by measuring vibration signals and surface strains.

[0003] There are many imperfections in the existing monitoring methods for automotive fastener vibration test equipment. Although resonance identification in the vibration spectrogram can locate parasitic resonance frequencies, it lacks refined analysis of the local strain distribution on the thread surface and is not easy to capture early signs of microcracks or fatigue damage. Although the application of photonic crystal films can reflect strain changes through wavelength shift, existing methods mostly stay in the static test stage, fail to effectively integrate dynamic vibration data with real-time strain monitoring, and cannot achieve visualization of the strain gradient on the entire surface of the fastener and real-time early warning and dynamic protection of abnormalities. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a monitoring method for an automotive fastener vibration test equipment, which solves the problems of inaccurate resonance frequency suppression and lack of dynamic protection mechanism in the existing monitoring methods for automotive fastener vibration test equipment.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, the present invention provides a monitoring method for an automotive fastener vibration test equipment, which includes spraying a photonic crystal film onto an automotive fastener, collecting the optical wavelength distribution data on the surface of the photonic crystal film, and generating a wavelength shift data stream; Calculating the strain value of the monitoring point of the automotive fastener by using the wavelength shift data stream, drawing a strain heat map and calculating the local strain gradient, setting a strain gradient threshold, and when the local strain gradient exceeds the strain gradient threshold, sending out an audible and visual alarm signal and transmitting it to the vibration table to activate the vibration table frequency reduction protection mechanism to obtain the operating state of the vibration table; Collecting vibration signals and generating a vibration spectrogram, constructing an equivalent impedance network model and analyzing the vibration spectrogram to identify parasitic resonance frequency points; Suppressing the band energy reflection in the parasitic resonance frequency points by using a hydraulic damper to obtain a vibration spectrum state, generating a reverse waveform by using a piezoelectric actuator, and using the reverse waveform to cancel the remaining standing waves in the vibration spectrum state to output a stable vibration state report form.

[0007] As a preferred solution of the monitoring method for the automotive fastener vibration test equipment of the present invention, wherein: the generation of the wavelength shift data stream refers to collecting the optical wavelength distribution data on the surface of the photonic crystal thin film using a laser interferometer, and numbering the optical wavelength distribution data on the surface of the photonic crystal thin film in spatial order to form monitoring points; Use the LabVIEW spectral processing suite to extract the wavelength peaks of each monitoring point and organize them to form a reflection spectrum database; Collect the reflection spectrum data of the photonic crystal thin film using an HR4000 spectrometer to form a reflection spectrum data set, compare the reflection spectrum data set with the reflection spectrum database, calculate the wavelength shift amount and organize it into a wavelength shift data stream.

[0008] As a preferred solution of the monitoring method for the automotive fastener vibration test equipment of the present invention, wherein: the calculation of the strain value of the automotive fastener monitoring point includes establishing a calibration curve, finding the wavelength shift amount closest to the wavelength shift data stream in the calibration curve, and converting the closest wavelength shift amount into the strain value of the automotive fastener monitoring point by linear interpolation.

[0009] As a preferred solution of the monitoring method for the automotive fastener vibration test equipment of the present invention, wherein: obtaining the operating state of the vibration table refers to organizing the strain values of the automotive fastener monitoring points to form a strain value data set, and using a three-dimensional optical scanner to create a three-dimensional geometric coordinate file of the automotive fastener; Use MATLAB software to extract the three-dimensional coordinates of the three-dimensional geometric coordinate file, match the strain values in the strain value data set with the three-dimensional coordinates to form a comprehensive data set; Use a Python interpreter to simplify the three-dimensional coordinates in the comprehensive data set into two-dimensional plane coordinates, construct a two-dimensional grid, find the monitoring point closest to each grid point in the comprehensive data set and assign a strain value to generate a stress thermogram; According to the stress thermogram, calculate the local strain gradient values between adjacent monitoring points and organize them into a local strain gradient value table, set a strain gradient threshold, compare each local strain gradient value in the local strain gradient table with the strain gradient threshold, and output an abnormal record file; According to the abnormal record file, start the warning mechanism to send out an audible and visual alarm signal, send the trigger instruction in the abnormal record file to the vibration table, and obtain the operating state of the vibration table after observing the change in the operating state of the vibration table.

[0010] As a preferred solution of the monitoring method for the automotive fastener vibration test equipment of the present invention, wherein: constructing the equivalent impedance network model means organizing the operating state of the vibration table into a vibration table operating state log file, and the vibration table operating state file includes vibration frequency and amplitude; Use LabVIEW software to create data input controls, record the vibration frequency and amplitude as excitation units, calculate the mass of the automotive fastener, the mass of the fixture, and the stiffness value of the automotive fastener, and label them as the automotive fastener mass unit, the fixture mass unit, and the automotive fastener stiffness unit respectively; Create connection controls, arrange all units in the order of vibration energy transfer to form an equivalent impedance network model.

[0011] As a preferred solution of the monitoring method for the automotive fastener vibration test equipment of the present invention, wherein: identifying the parasitic resonance frequency points means using an acceleration sensor to collect the vibration signals of the automotive fastener and the fixture to generate a vibration signal file; Perform Fourier transform processing on the vibration signal file, calculate the amplitude values of all vibration frequencies to form a vibration spectrum diagram; Check the amplitude peaks in the vibration spectrum diagram, use the equivalent impedance network model to predict the theoretical amplitude peaks, set the amplitude difference threshold, calculate the difference between the amplitude peak and the theoretical amplitude peak and compare it with the amplitude difference threshold to identify the parasitic resonance frequency points.

[0012] As a preferred solution of the monitoring method for the automotive fastener vibration test equipment of the present invention, wherein: outputting the stable vibration state report form means selecting a hydraulic damper as a suppressor, calculating the viscosity coefficient of the hydraulic damper and performing suppression verification to obtain the damping adjustment result; According to the damping adjustment result, apply a signal at a non-parasitic resonance frequency point to the automotive fastener, and record the vibration frequency and amplitude of the automotive fastener to form a vibration spectrum state; Use the vibration spectrum state to identify the standing wave, calculate the phase of the standing wave, and at the same time use a piezoelectric actuator to calculate the voltage of the reverse waveform, and integrate the voltage of the reverse waveform, the vibration spectrum state, and the phase of the standing wave to form reverse waveform parameters; Generate a reverse waveform using the reverse waveform parameters and cancel the standing wave to obtain a stable vibration state report form.

[0013] In a second aspect, the present invention provides a monitoring system for an automotive fastener vibration test equipment, including a data generation module, spraying a photonic crystal thin film onto the automotive fastener, collecting the optical wavelength distribution data on the surface of the photonic crystal thin film, and generating a wavelength shift data stream; An operation module that calculates the strain value of the monitoring points of automotive fasteners using the wavelength-offset data stream, draws a strain heat map, analyzes the local strain gradient, sets a strain gradient threshold, and when the local strain gradient exceeds the strain gradient threshold, emits an audible and visual alarm signal and transmits it to a vibration table to activate the vibration table's frequency reduction protection mechanism to obtain the operating state of the vibration table; A frequency identification module that collects vibration signals and generates a vibration spectrogram, constructs an equivalent impedance network model, analyzes the vibration spectrogram, and identifies parasitic resonance frequency points; A state generation module that suppresses the band energy reflection in the parasitic resonance frequency points using a hydraulic damper to obtain a vibration spectrum state, generates a reverse waveform through a piezoelectric actuator, and uses the reverse waveform to cancel the remaining standing waves in the vibration spectrum state and outputs a stable vibration state report form.

[0014] In a third aspect, the present invention provides a computer device, including a memory and a processor, where the memory stores a computer program, and: when the computer program is executed by the processor, any step of the monitoring method of the automotive fastener vibration test device as described in the first aspect of the present invention is implemented.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and: when the computer program is executed by the processor, any step of the monitoring method of the automotive fastener vibration test device as described in the first aspect of the present invention is implemented.

[0016] The beneficial effects of the present invention are as follows: The present invention can immediately trigger early warning and protection measures when detecting an abnormal strain gradient, effectively avoiding the risk of equipment damage caused by inaccurate suppression of resonance frequencies, thereby improving the safety and efficiency of testing. At the same time, the constructed equivalent impedance network model improves the accuracy of identifying parasitic resonance frequency points, solves the problem of inaccurate suppression of resonance frequencies, and also reduces unnecessary energy consumption and mechanical damage. By calculating the strain value of the monitoring points of automotive fasteners, the local strain of automotive fasteners is efficiently quantified, greatly improving the abnormal detection accuracy of the dynamic protection mechanism and making up for the lack of refined strain analysis in the existing monitoring methods of automotive fastener vibration test devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a flowchart for generating a wavelength-offset data stream.

[0019] Figure 2 Generate a strain heat map and a gradient analysis schematic diagram.

[0020] Figure 3 Construct an equivalent impedance network model and identify parasitic resonances.

[0021] Figure 4 A flowchart for hydraulic damping suppression and piezoelectric waveform cancellation. Specific implementation manners

[0022] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific implementation manners of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art may make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0024] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.

[0025] Refer to Figures 1 to 4 , this embodiment provides a monitoring method for an automotive fastener vibration test device, including the following steps: S1. Spray a photonic crystal thin film onto the automotive fastener, collect the optical wavelength distribution data on the surface of the photonic crystal thin film, and generate a wavelength shift data stream.

[0026] Including the following steps, S1.1. Use a high-precision spraying device to spray a cadmium selenide quantum dot-polymer composite film (i.e., a photonic crystal thin film) on the thread surface of the automotive fastener (such as a bolt or nut). When preparing the spraying solution, mix cadmium selenide quantum dots and polymethyl methacrylate according to a mass ratio (such as 1:10), add an appropriate amount of toluene solvent and stir evenly until a stable suspension is formed. The spraying device uses a pneumatic spray gun.

[0027] Fix the automotive fastener on a rotating fixture, and move the spray gun axially along the thread surface to ensure uniform coverage of the photonic crystal thin film.

[0028] S1.2. Install the automotive fastener with the attached photonic crystal film into the test fixture (the test fixture is made of aluminum alloy and equipped with a precision threaded clamping device). After installation, use a laser interferometer to scan the surface of the photonic crystal film (select a helium-neon laser as the light source). During operation, adjust the optical path of the laser interferometer so that the laser beam is perpendicularly incident on the surface of the photonic crystal film. Taking the axial direction of the threaded surface as the reference, start scanning point by point from one end, moving 1 millimeter each time until the entire threaded area is covered.

[0029] During the scanning process, the laser interferometer records the reflection spectrum of the photonic crystal film in the unstrained state, and the wavelength acquisition range is 400 - 800 nanometers. After each scan, the reflection spectrum is automatically saved. For example, the reflection spectrum collected at the top of the thread may be 650 nanometers, which is recorded as the initial state and the wavelength distribution data of the surface of the photonic crystal film is generated.

[0030] S1.3. Transmit the wavelength distribution data of the surface of the photonic crystal film to the computer terminal, and use the LabVIEW spectral processing suite to organize the wavelength distribution data. The specific operation is as follows: The LabVIEW spectral processing suite displays multiple waveform diagrams, and each waveform diagram corresponds to the wavelength peak of a certain point on the threaded surface. Manually set the data in the LabVIEW spectral processing suite, that is, taking the axial starting point of the threaded surface as the reference, number the reflection spectra in the order of spatial position to form monitoring points. For example, starting from the starting point, they are named P1, P2, P3 in sequence every 1 millimeter until the entire threaded area is covered.

[0031] For each monitoring point, the LabVIEW spectral processing suite will automatically identify and extract the wavelength peak of the reflection spectrum. For example, the wavelength peak at point P1 is 650 nanometers, and at point P2 is 648 nanometers, and so on. After extraction, click the data table generation function in LabVIEW to organize all the monitoring points and the corresponding wavelength peaks into a structured table (CSV format). For example, the table contains two columns. The first column is the position number (P1, P2, etc.), and the second column is the wavelength peak (650 nanometers, 648 nanometers, etc.), forming a reflection spectrum database.

[0032] S1.4. Connect the automotive fastener with the attached photonic crystal film to the test fixture of the vibration test equipment (select an electromagnetic vibration table with a working frequency range of 5 - 2000 Hz), start the vibration test equipment to simulate the dynamic load during vehicle operation (set the vibration mode as sinusoidal sweep frequency, and the frequency gradually increases from 20 Hz to 500 Hz). At the same time, select an HR4000 spectrometer and fix the optical probe of the spectrometer on a three-axis fine adjustment frame. Align the probe lens with the photonic crystal film on the threaded surface of the automotive fastener, keep the distance about 10 millimeters, and adjust the angle to be perpendicular incidence to reduce the reflection error.

[0033] The scanning area of the optical probe covers the entire thread surface. Specifically, by manually adjusting the three-axis fine adjustment frame, the probe moves point by point along the thread axis from the starting point to the ending point, staying every 1 mm. The acquisition frequency is set at 500 times per second. The HR4000 spectrometer will continuously record the reflection spectrum data of the photonic crystal thin film (for example, the wavelength peak of a certain point on the thread surface is 650 nm in the initial state and may become 650.2 nm after vibration), generating a complete reflection spectrum data set.

[0034] S1.5. Conduct wavelength shift detection on the reflection spectrum data set. Specifically, transfer the reflection spectrum data set to the computer processing terminal through the USB interface, and use the LabVIEW spectrum processing suite to automatically compare the reflection spectrum data of the photonic crystal thin film collected in real time by the spectrometer with the corresponding values in the initial reflection spectrum database. For example, the initial value of point P1 is 650 nm and the real-time value is 650.15 nm. Calculate the difference, which is the wavelength shift amount of 0.15 nm.

[0035] If the wavelength shift amount is less than 0.1 nm, it is recorded as no significant change; if the wavelength shift amount exceeds 0.1 nm, it is marked as an effective shift caused by strain. The LabVIEW spectrum processing suite arranges the wavelength shift amounts of all monitoring points in chronological order into a real-time wavelength shift data stream. For example, 500 groups of data streams are generated per second, and each group contains the position number (such as P1, P2) and the corresponding wavelength shift amount (such as 0.15 nm, 0.12 nm).

[0036] S2. Calculate the strain values of the monitoring points of the automotive fasteners using the wavelength shift data stream, draw a strain heat map and calculate the local strain gradient, set a strain gradient threshold. When the local strain gradient exceeds the strain gradient threshold, send an audible and visual alarm signal and transmit it to the vibration table to activate the vibration table's frequency reduction protection mechanism to obtain the operating state of the vibration table.

[0037] It includes the following steps, S2.1. Establish a calibration curve (used to convert the wavelength shift amount in the wavelength shift data stream into a strain value). The specific establishment process is as follows: Prepare a group of automotive fastener samples of the same material and structure, spray the photonic crystal thin film onto the thread surface of the automotive fastener samples, and fix them on the strain test device. Use a high-precision strain gauge (such as a resistance strain gauge) to measure the actual strain value on the thread surface, and at the same time use a laser interferometer to record the wavelength peak of the reflection spectrum of the photonic crystal thin film.

[0038] Apply a dynamic load gradually, for example, increasing from 0 Newton to 100 Newtons, with an increase of 10 Newtons each time. Record the strain values and the corresponding wavelength shifts under each dynamic load respectively. For example, when the dynamic load is 20 Newtons, the strain value measured by the resistance strain gauge is 100 strain, and the wavelength shift is 0.1 nanometer; when the dynamic load is 40 Newtons, the strain value is 200 strain, and the wavelength shift is 0.2 nanometer. Through multiple measurements, collect at least 10 sets of data pairs and organize them into a table. The first column is the wavelength shift (such as 0.1 nanometer, 0.2 nanometer), and the second column is the strain value (such as 100 strain, 200 strain). Save this table as a CSV file and import it into the LabVIEW spectral processing suite as a calibration curve.

[0039] S2.2. After the calibration curve is established, it is necessary to calculate the strain value at the monitoring point where the photonic crystal thin film is located on the thread surface of the automotive fastener. The specific calculation process is as follows: The LabVIEW spectral processing suite first reads each wavelength shift in the real-time wavelength shift data stream. For example, the wavelength shift at point P1 is 0.15 nanometers. At the same time, find the wavelength shift in the calibration curve that is closest to 0.15 nanometers. For example, in the calibration curve, 0.1 nanometer corresponds to 100 strain, and 0.2 nanometer corresponds to 200 strain. Since 0.15 nanometers is between 0.1 nanometer and 0.2 nanometers, the linear interpolation method needs to be used to determine the specific strain value. Specifically, it is divided into six steps. Taking point P1 as an example, the first step is to calculate the difference between the two known wavelength shifts in the calibration curve (i.e., the wavelength shift range), and it is obtained that 0.2 nanometers minus 0.1 nanometers equals 0.1 nanometer. The second step is to calculate the increment of the wavelength shift relative to the smaller value in the calibration curve, and it is obtained that 0.15 nanometers minus 0.1 nanometers equals 0.05 nanometer. The third step is to calculate the difference between the two strain values in the calibration curve (i.e., the change range of the strain value), and it is obtained that 200 strain minus 100 strain equals 100 strain. The fourth step is to determine the proportion of the wavelength increment at point P1 in the wavelength shift range (i.e., the proportion of the wavelength increment in the total range), and it is obtained that 0.05 nanometers divided by 0.1 nanometer equals 0.5. The fifth step is to apply the proportion of the wavelength increment in the total range to the change range of the strain value (calculating the increment of the strain value), and it is obtained that 0.5 multiplied by 100 strain equals 50 strain. The sixth step is to add the strain value increment to the change range of the strain value, and it is obtained that 50 strain plus 100 strain equals 150 strain, which is the final strain value at point P1.

[0040] The LabVIEW spectral processing suite sequentially organizes the strain values at the monitoring points where the photonic crystal thin film is located on the thread surface of the automotive fastener to form a strain value data set (including the monitoring point numbers), such as P1, 150 strain; P2, 120 strain.

[0041] S2.3. Create a 3D geometric coordinate file for the threaded surface of automotive fasteners. The specific creation process is as follows: Use a 3D optical scanner (such as GOMATOS Core) to perform a full-surface scan of the automotive fastener. Fix the automotive fastener on a rotating platform, and the rotating platform rotates at a high speed. The 3D optical scanner collects the geometric data of the threaded surface point by point. The geometric data refers to the 3D coordinates of each point on the threaded surface of the automotive fastener, in millimeters, and is specifically composed of three values: the X-axis (distance along the threaded axis), the Y-axis (distance along the threaded radial direction), and the Z-axis (distance along the threaded height). For example, the coordinate of the thread starting point is (0, 0, 0), the point 1 millimeter away from the starting point is (1, 0, 0), and a certain point at the top of the thread may be (2, 0.5, 0.1). The 3D optical scanner records the 3D coordinates of each point through the triangulation principle (that is, by measuring the angle and distance of the light emitted from the 3D optical scanner, hitting the threaded surface and then reflecting back, so as to calculate the spatial position of each point on the threaded surface), and the scanning range covers the entire threaded area. After the collection is completed, convert the 3D coordinates of each point into an STL format file to form a 3D geometric coordinate file for the threaded surface of the automotive fastener.

[0042] In the MATLAB software, create a script command to read the 3D geometric coordinate file of the threaded surface of the automotive fastener and extract the 3D coordinates of all points in the 3D geometric coordinate file. Manually specify the coordinate positions corresponding to the monitoring point numbers in the strain value dataset, and select equally spaced points along the threaded axis from the STL format file. For example, the 3D coordinates corresponding to point P1 are (0, 0, 0), point P2 corresponds to (1, 0, 0), and point P3 corresponds to (2, 0, 0). Then match the strain values in the strain value dataset with all the 3D coordinates one by one. The specific operation is to create a new table in the script. The first column inputs the monitoring point numbers (such as P1, P2), the second column inputs the strain values (such as 150 strain, 120 strain), and the third column inputs the corresponding 3D coordinates (such as 0, 0, 0; 1, 0, 0). For example, the matching of point P1 is (number P1, 150 strain, coordinate 0, 0, 0), and point P2 is (number P2, 120 strain, coordinate 1, 0, 0). If the number of coordinate points in the STL format file is more than the number of monitoring points, only select the coordinates that are consistent with the monitoring point positions and ignore the remaining points. If the monitoring point position has a slight deviation, take the 3D coordinates of the nearest point. For example, the 3D coordinates of point P3 should be (2, 0, 0). If the 3D coordinates of the nearest point in the STL format file are (2.02, 0, 0), then use (2.02, 0, 0) as the standard. After the matching is completed, save the script table as a comprehensive dataset.

[0043] S2.4. Use the Python interpreter to load the comprehensive dataset and simplify the three-dimensional coordinates in the comprehensive dataset into two-dimensional plane coordinates. The specific method is to extract the X-axis (along the thread axis) and the Y-axis (along the thread radial direction) as the horizontal and vertical axes for plotting, and ignore the Z-axis to simplify the visualization. Extract the X value and Y value of each monitoring point from the comprehensive dataset. At the same time, construct a two-dimensional grid for the thread surface. The two-dimensional grid uses the X-axis from 0 mm to the thread length (e.g., 20 mm) as the horizontal axis and the Y-axis from -1 mm to 1 mm (i.e., covering the entire range of the thread radial direction) as the vertical axis. For each grid point, find the monitoring point in the comprehensive dataset that is closest. For example, if the grid point (1.5, 0) is close to the P2 point (1, 0), then assign a strain value of 120 microstrain. Since the coordinates of the grid point (1.5, 0) are only 0.5 mm apart from the P2 point (1, 0) on the X-axis, which is less than the distance to other monitoring points, directly adopt the 120 microstrain of the P2 point); if a direct match cannot be made, take the average value of the adjacent monitoring points. For example, for the grid point (1.5, 0.5), take the average of the P2 and P3 points (assuming the strain value of the P3 point is 180 microstrain, then 120 microstrain of the P2 point plus 180 microstrain equals 300 microstrain, divided by 2, resulting in 150 microstrain).

[0044] Configure the plotting parameters in the Python interpreter to generate a stress heat map. Specifically, create a blank canvas, use the X coordinates and Y coordinates of the two-dimensional grid as the horizontal and vertical axis ranges of the blank canvas, and use the strain value as the basis for color coding. Set the color grading rule, that is, a strain value less than 100 microstrain is mapped to green, 100 to 200 microstrain is mapped to yellow, and greater than 200 microstrain is mapped to red. For example, the strain value of the P1 point is 150 microstrain, corresponding to yellow. Then draw color blocks for each grid point one by one. Traverse all the grid point coordinates, read the corresponding strain value, determine the color, and fill it into the blank canvas. For example, the grid point (0, 0) is green, and (1, 0) is yellow. After drawing, add a color bar and mark the range of the strain value (0~300 microstrain) to visually distinguish the high-strain area and the low-strain area.

[0045] S2.5. Next, it is necessary to calculate the local strain gradient between adjacent monitoring points. Specifically, select adjacent monitoring point pairs along the thread axis (i.e., the X-axis) from the comprehensive dataset. For example, P1 (coordinates 0, 0, 0, strain value is 150 microstrain) and P2 (coordinates 1, 0, 0, strain value is 120 microstrain). Take the difference between the strain values of the two points (150 microstrain minus 120 microstrain equals 30 microstrain), and divide it by the distance between the two points (i.e., the spatial distance between adjacent monitoring points on the surface of the automotive fastener thread. For example, the distance between the coordinates of point P1 (0, 0, 0) and point P2 (1, 0, 0) is 1 mm), resulting in a local strain gradient of 30 microstrain per millimeter. Repeat the calculation of the local strain gradient for all adjacent monitoring point pairs. For example, the local strain gradient between P2 and P3 (assuming P3 has a strain value of 180 microstrain and coordinates 2, 0, 0) is 60 microstrain per millimeter, and organize it into a table of local strain gradient values.

[0046] Set the strain gradient threshold. The specific setting basis is as follows: Conduct multiple vibration fatigue experimental tests on a set of bolt samples (such as M10 bolts) with the same material and geometric dimensions as the test automotive fasteners. The experimental tests use an electromagnetic vibration table to apply a dynamic load with a sinusoidal sweep frequency. During each test, record the wavelength offset and convert it into a strain value, and at the same time calculate the local strain gradient between adjacent monitoring points. Check whether there are microcracks or plastic deformations on the bolt surface after each load application. For example, in a certain test, when the local strain gradient of the monitoring point reaches 48 microstrain per millimeter, no damage is seen on the bolt surface, while in another test, when the local strain gradient reaches 52 microstrain per millimeter, an initial crack is observed at the root of the bolt through a microscope. Based on the comprehensive test results of multiple times, it is statistically found that when the local strain gradient of the monitoring point exceeds 50 microstrain per millimeter (assuming this situation), the damage probability on the bolt surface increases significantly (such as 6 out of 8 times there are microcracks), then select 50 microstrain per millimeter as the specific numerical range of the strain gradient threshold (the numerical range of the strain gradient threshold can be adjusted according to the actual situation).

[0047] Compare each local strain gradient value in the local strain gradient table with the strain gradient threshold. For example, the local strain gradient value of P1 and P2 is 30 microstrain per millimeter, which is less than 50 microstrain per millimeter, and it is determined to be a normal local strain gradient. If the local strain gradient of P2 and P3 is 60 microstrain per millimeter, which is greater than 50 microstrain per millimeter, it is determined to be an abnormal local strain gradient. For abnormal situations, record the relevant monitoring point numbers (such as P2, P3), strain values (120 microstrain, 180 microstrain), and coordinates (1, 0, 0, 2, 0, 0), and organize them into an abnormal record file.

[0048] S2.6. Based on the exception record file, start the warning mechanism to notify the operator. Specifically, connect an audible and visual alarm (equipped with a red flashing light and a decibel buzzer) to the computer processing terminal. Use the control interface in the Python interpreter to send a start command to the audible and visual alarm, and synchronously transmit the content of the exception record file to the monitoring display screen. The operator runs a display program in the Python interpreter to present the abnormal monitoring point number, strain value, and coordinates in tabular form. For example, it shows P2, 120 strain, 1,0,0 and P3, 180 strain, 2,0,0, and highlights the abnormal area on the strain heat map (such as the area from P2 to P3 is marked with a flashing red border), triggering the audible and visual alarm signal.

[0049] S2.7. Convert the audible and visual alarm signal into a control signal and transmit it to the control terminal of the vibration test equipment (i.e., the vibration table) to activate the frequency reduction protection mechanism. Specifically, through the serial communication function in the Python interpreter, send the trigger instruction in the exception record file to the vibration table in the form of a data packet. After receiving the trigger instruction, the vibration table automatically adjusts the operating parameters of the vibration table, that is, reduces the vibration frequency from the current value (assumed to be 500 Hz) by 10 Hz per second until it reaches 100 Hz, and at the same time gradually reduces the amplitude from 5 mm to 2 mm, reducing by about 0.5 mm each time. During the adjustment, record the operating state of the vibration table once per second to generate a log file of the vibration frequency and amplitude.

[0050] The operator observes the change in the operating state of the vibration table through the monitoring display screen. For example, after confirming that the frequency has dropped to 100 Hz, reload the strain heat map and check whether the local strain gradient of the monitoring point has returned below 50 strain per millimeter. If it returns to normal, stop the frequency reduction protection and maintain the current state; if it is still abnormal, continue to reduce the vibration frequency to 50 Hz. Finally, output the operating state of the vibration table (in the form of a log file).

[0051] S3. Collect vibration signals and generate a vibration spectrogram, construct an equivalent impedance network model, and analyze the vibration spectrogram to identify parasitic resonance frequency points.

[0052] It includes the following steps S3.1. Construct an equivalent impedance network model based on the physical properties of automotive fasteners, fixtures, and vibration tables. Specifically, the physical properties of automotive fasteners include bolt diameter (e.g., 10 mm), thread length (e.g., 20 mm), automotive fastener material (e.g., high-strength steel), density, and elastic modulus (e.g., 200 GPa). The physical properties of the fixture are the contact surface dimensions (e.g., width 50 mm, length 50 mm, thickness 10 mm, directly measured by an electronic caliper), the density of the fixture, and the elastic modulus of the fixture (e.g., 70 GPa). The physical property of the vibration table is the contact stiffness, which is obtained through testing. The specific testing method is as follows: Apply a Newton force (assumed to be 100 N) between the contact surface of the fixture and the vibration table. Use a laser displacement sensor, fixed on one side of the fixture and aligned with the contact surface. After applying a force of 100 N, record the displacement distance of the fixture in the direction of the Newton force (i.e., the displacement distance, assumed to be 0.1 mm). Divide the applied 100 N force by the measured displacement distance of 0.1 mm to obtain a contact stiffness of 1000 N / mm.

[0053] S3.2. Select LabVIEW software as the processing software. Open the main page of LabVIEW to load the operation status log file of the vibration table (vibration frequency, amplitude). Create data input controls and record the vibration frequency and amplitude as the excitation unit, representing the energy input of the vibration table. Then, calculate the mass of the automotive fastener according to its physical properties. The specific calculation process is as follows: Since the bolt diameter is 10 mm and the thread length is 20 mm, the bolt is approximately a cylinder. Then the mass of the automotive fastener is the square of the bolt diameter multiplied by the thread length and then multiplied by one-fourth of pi, approximately 12.3 g (create a mass unit control in LabVIEW software, input 12.3 g, and label it as the automotive fastener mass unit).

[0054] Calculate the mass of the fixture according to the contact surface dimensions of the fixture. The specific calculation process is as follows: Multiply the width of 50 mm by the length of 50 mm and then by the thickness of 10 mm to obtain the volume of the fixture as 25000 cubic millimeters. Convert the volume unit of the fixture volume to cubic meters, that is, 25000 cubic millimeters divided by 1000000000 (1 cubic meter is equal to 1000000000 cubic millimeters), which is 0.000025 cubic meters. Assume the density of the fixture is 2700 kg / m³. Then multiply the volume of the fixture by the density of the fixture to obtain the mass of the fixture (0.000025 × 2700 = 0.0675 kg. Convert the mass unit of the fixture mass to grams, that is, 0.0675 kg multiplied by 1000 (1 kg is equal to 1000 g), to obtain a mass of 67.5 g). Create another mass unit control in LabVIEW software and input the finally calculated mass of the fixture, and label it as the fixture mass unit.

[0055] Calculate the stiffness value of the automotive fastener (obtained by multiplying the cross-sectional area of the automotive fastener by the modulus of elasticity and dividing by the thread length. Assuming the cross-sectional area is 78.5 square millimeters, the stiffness value of the automotive fastener is 78.5 multiplied by 200 and then divided by 20, resulting in 785 Newtons per millimeter), create a stiffness unit control, input the stiffness value of the automotive fastener, and label it as the automotive fastener stiffness unit.

[0056] Create a connection control, arrange all units in the order of vibration energy transfer. Specifically, connect the excitation unit to the fixture mass unit and the fixture stiffness unit in sequence, and then connect to the automotive fastener mass unit and the automotive fastener stiffness unit to form an equivalent impedance network model.

[0057] S3.3. Collect vibration signals and generate a vibration spectrogram. Specifically, install an acceleration sensor on the vibration table and fix it at the core positions of the automotive fastener and the fixture, that is, one acceleration sensor is installed on the bolt head of the automotive fastener, and the other acceleration sensor is installed near the bolt where the fixture is connected to the vibration table. After installation, connect the acceleration sensor to the data acquisition device (such as NI USB-4431 acquisition card), start the vibration table, and maintain the previous vibration table operating state, such as a vibration frequency of 100 Hertz and an amplitude of 2 millimeters, collect the vibration signals of the automotive fastener and the fixture, and generate a vibration signal file (including timestamps and acceleration values, such as 0.001 seconds, 0.5g).

[0058] S3.4. Use DIAdem software as the processing software and select the Fourier transform tool in DIAdem software to perform Fourier transform processing on the vibration signal file. Specifically, select the acceleration values in the vibration signal file (such as 0.5g, 0.6g), and split the time series: split the acceleration values. For example, read the acceleration values within a 10-second timestamp, a total of 10,000 points and divide them into 10 1-second segments, each segment containing 1,000 acceleration values (for example, the first segment covers the acceleration values (0.5g, 0.6g) from 0.001 seconds to 1 second, the second segment covers 1.001 seconds to 2 seconds, and so on). Then apply the Hanning window. For each segment, select the window function tool in DIAdem software and apply the Hanning window. DIAdem software automatically generates 1,000 point weight values, the first point weight value and the last point weight value are close to 0 (such as 0.01), and the 500th point weight is close to 1 (such as 0.99). Multiply each point acceleration value by the corresponding weight value. For example, the 1st point 0.5g multiplied by 0.01 gives 0.005g, and the 500th point 0.6g multiplied by 0.99 gives 0.594g to form the windowed segment data.

[0059] Perform Fourier transform on each windowed segment data and calculate the amplitude of each vibration frequency. Specifically, for each vibration frequency (e.g., 150 Hz), calculate the contributions of the sine and cosine components, that is, traverse 1000 acceleration values (e.g., 0.005g, 0.594g), multiply each acceleration value by the sine value corresponding to 150 Hz (i.e., sin(2π×150×t), where t is time, such as 0.001 s) and the cosine value (cos(2π×150×t)), and accumulate them separately. For example, the 1st point 0.005g multiplied by sin(2π×150×0.001) gives 0.002g, and the sum of the 1000 points gives the total sine component (e.g., 0.1g). The cosine component is the same, and the accumulated value is 0.05g. Then take the square of the total sine component (i.e., 0.01) plus the square of the total cosine component (i.e., 0.0025), sum them to get 0.0125, take the square root to get 0.112g, and then multiply by 2 and divide by 1000 (1000 acceleration values) to obtain the amplitude value of the vibration frequency of approximately 0.224g.

[0060] Integrate the amplitude values of all vibration frequencies and calculate the average spectrum of the amplitude values. For each frequency (e.g., 150 Hz), extract the amplitude values of multiple segments (e.g., 10), such as 0.223g, 0.225g, 0.224g, etc., add the 10 amplitude values (e.g., 0.223 + 0.225 +... = 2.23g, 2.23g is an assumed case), divide by 10, and obtain the average amplitude value at the 150 Hz vibration frequency as 0.223g. Repeat the calculation process to calculate the average spectrum of all amplitude values and generate a vibration spectrum diagram, such as 150Hz, 0.224g, 200Hz, 0.180g.

[0061] S3.5. Use the equivalent impedance network model to analyze the resonance frequency in the vibration spectrum diagram. Specifically, check each amplitude peak in the vibration spectrum diagram one by one (the amplitude peak refers to the highest point in the vibration spectrum diagram, that is, the maximum amplitude value. For example, the maximum amplitude value at the 170 Hz vibration frequency is 0.8g, and the maximum amplitude value at the 200 Hz vibration frequency is 0.7g). Taking the 150 Hz vibration frequency as an example, use the equivalent impedance network model to predict the theoretical amplitude peak. The specific process is as follows: First, calculate the natural frequency by dividing the stiffness value of the automotive fastener (785 N / mm) by the mass of the automotive fastener (12.3 g, i.e., 0.0123 kg), take the square root to get 8000, and then divide by 2π (about 6.283) to obtain approximately 1273 Hz. Then determine the base amplitude (i.e., the excitation acceleration, which can be understood as the acceleration generated by the vibration table during vibration and is obtained according to the operating state of the vibration table. For example, for a vibration frequency of 100 Hz and an amplitude of 2 mm, the expression for the excitation acceleration is: ; Among them, Represents the excitation acceleration, Represents the vibration frequency, i.e., 100 Hz, Represents the amplitude, i.e., 2 mm, approximately equal to 789 m / s², and in the form of grams it is 80.5 g.

[0062] Considering the actual output limit of the shaker and the fixture attenuation, the excitation acceleration is changed to 0.9 g. Since the damping ratio (which refers to the rate at which vibration energy is dissipated due to damping, with a numerical range from 0 to 1, and in the vibration testing of automotive fasteners and fixtures, the damping ratio measures the rate at which the vibration amplitude decreases over time. For example, a damping ratio of 0.02 means that the vibration amplitude decays slowly, belonging to light damping, which is suitable for the low-frequency vibration response of high-strength steel and aluminum alloy materials, so the damping ratio is set to 0.02) will weaken the amplitude peak, it is necessary to calculate the weakening ratio of the amplitude peak, i.e., 1 - 0.02 = 0.98, and multiply the weakening ratio by the base amplitude of 0.9 g to obtain the theoretical amplitude peak of approximately 0.75 g.

[0063] S3.6. Set the amplitude difference threshold. The setting basis is to prepare a set of bolt samples with the same material and geometric dimensions as the test automotive fasteners, as well as the same fixture, apply a sine sweep vibration from 20 to 500 Hz, and use an acceleration sensor to collect vibration signals, generate a vibration spectrum diagram and record the amplitude peak at the same time. Subsequently, use the equivalent impedance network model to estimate the theoretical amplitude peak. Compare the theoretical amplitude peaks and the actual amplitude peaks of multiple tests, and statistically analyze the difference distribution. For example, at 150 Hz, the differences in 10 tests are 0.03 g, 0.05 g, 0.06 g, etc., and the average value is approximately 0.04 g, while at 200 Hz, the differences are 0.3 g, 0.35 g, etc., and the average value is approximately 0.4 g. When a high amplitude occurs at a frequency (such as 150 Hz) where the difference is less than 0.1 g, use a microscope to observe that there will be tiny fatigue marks on the thread surface, indicating the existence of resonance risk. When there is no obvious damage at a frequency (such as 200 Hz) where the difference is greater than 0.1 g, it belongs to normal vibration. Conduct multiple groups of tests comprehensively, and set the difference of 0.1 g as the demarcation point (the specific value of the amplitude difference threshold can also be dynamically adjusted according to the actual situation).

[0064] Calculate the difference between the theoretical amplitude peak and the amplitude peak (actual). When the difference is less than the amplitude difference threshold, mark the vibration frequency as a parasitic resonance frequency point (for example, for a vibration frequency of 150 Hz, the theoretical amplitude peak is 0.75 g, the actual amplitude peak is 0.8 g, then the difference is 0.05 g, which is less than the amplitude difference threshold, so mark the vibration frequency of 150 Hz as a parasitic resonance frequency point). When the difference is greater than the amplitude difference threshold, mark the vibration frequency as a normal vibration frequency.

[0065] S4. Use a hydraulic damper to suppress the energy reflection of the frequency band at the parasitic resonance frequency point, obtain the vibration spectrum state, generate a reverse waveform through a piezoelectric actuator, use the reverse waveform to cancel the remaining standing waves in the vibration spectrum state, and output a stable vibration state report form.

[0066] including the following steps, S4.1. Select a hydraulic damper as the suppressor and calculate the viscosity coefficient of the hydraulic damper. Specifically, the calculation is divided into the following steps (taking a vibration frequency of 150 Hz as an example): First step, convert the actual amplitude peak value into an acceleration value, that is, 0.8g multiplied by 9.8 (acceleration due to gravity), to get 7.84 meters per second squared; Second step, estimate the vibration energy at the parasitic resonance frequency point, and the vibration energy is equal to half of the product of the mass of the automotive fastener and the square of the acceleration, that is, 0.0123×(7.84) 2 ×0.5 (kinetic energy fixed coefficient) ≈ 0.000378 joules; The third step is to determine the energy absorbed by the hydraulic damper. Since it is necessary to suppress the energy reflection of the frequency band, the hydraulic damper needs to absorb twice the vibration energy, that is, 0.000378×2 = 0.000756 joules; The fourth step is to estimate the piston speed of the hydraulic damper. The piston speed is the amplitude of the vibration table (2 mm, that is, 0.002 m) multiplied by 2π and then multiplied by the vibration frequency, that is, 0.002×2π×150 ≈ 0.9425 meters per second, and take the approximate value of 0.01 meters per second (considering actual attenuation); The fifth step is to calculate the damping force of the hydraulic damper, that is, the absorbed energy of the hydraulic damper divided by the distance the piston moves (assumed to be 0.01 m), then the damping force is 0.000756÷0.01 = 0.0756 newtons. The sixth step is to divide the damping force by the piston speed to obtain the final viscosity coefficient of 0.0756÷0.01 = 7.56 newton-seconds per meter.

[0067] S4.2. Adjust and verify the viscosity coefficient of the hydraulic damper. Specifically, manually open the control panel of the hydraulic damper and check the solenoid valve adjustment knob (marked with an opening degree of 0 - 100%. The opening degree refers to the opening degree of the solenoid valve of the hydraulic damper, expressed as a percentage, ranging from 0% (fully closed) to 100% (fully open), which is used to control the flow rate of hydraulic oil in the damper circuit, thereby adjusting the liquid viscous resistance and affecting the magnitude of the viscosity coefficient. For example, an opening degree of about 50% means the solenoid valve is partially open and the hydraulic oil flow rate is moderate). Read the viscosity coefficient. For a vibration frequency of 150 Hz, the viscosity coefficient of the hydraulic damper is 7.56 Newton-seconds per meter. According to the damper manual (which refers to the written technical information provided by Vickers for the servo hydraulic damper, including the technical specifications, operation instructions, and performance parameters of the hydraulic damper. The manual records the conversion table between the solenoid valve opening degree and the output viscosity coefficient of the hydraulic damper. For example, it is noted in the manual that an opening degree of 50% corresponds to approximately 8 Newton-seconds per meter, and an opening degree of 35% corresponds to approximately 6 Newton-seconds per meter), since an opening degree of 50% corresponds to approximately 8 Newton-seconds per meter, adjust the solenoid valve knob to about 49% (slightly lower than 50%), which is close to 7.56 Newton-seconds per meter.

[0068] Start the vibration table and apply test signals one by one (set the vibration frequency to 150 Hz and the amplitude to 2 mm). Use an acceleration sensor to measure the amplitude of the automotive fastener, read the display of the sensor and record the amplitude decrease. For example, if it decreases from 0.8 g to 0.4 g, it indicates that the reflected energy at 150 Hz is absorbed by the hydraulic damper. Organize all the adjustment results and name the adjustment results in the form of a table as the damping adjustment result, which includes three columns: vibration frequency, viscosity coefficient, and adjusted amplitude. For example, 150 Hz, 7.56 N·s / m, 0.4 g.

[0069] S4.3. Generate the vibration spectrum state based on the damping adjustment results. Specifically, start the vibration table again and apply signals at non-parasitic resonance frequency points, such as 100 Hz (amplitude 2 mm). Use an acceleration sensor to measure the amplitude of the automotive fastener and record the display value of the acceleration sensor, such as 0.1 g. Then apply a vibration frequency of 300 Hz and also record the amplitude of the automotive fastener, such as 0.08 g. Organize all the amplitudes in the form of a table named the vibration spectrum state table, which includes the vibration frequency and amplitude. For example, 100 Hz, 0.1 g, 150 Hz, 0.4 g, 200 Hz, 0.3 g, 300 Hz, 0.08 g (if the amplitude at a certain parasitic resonance frequency point is still high, such as 0.6 g at 150 Hz, then slightly adjust the viscosity coefficient, such as increasing it to 8 Newton-seconds per meter, and re-measure the amplitude).

[0070] S4.4. Identify the residual standing wave using the vibration spectrum state (the residual standing wave refers to the vibration wave that still exists in the vibration spectrum state after the hydraulic damper suppresses the energy reflection at the parasitic resonance frequency point). Specifically, set the amplitude background level (i.e., the acceleration amplitude of automotive fasteners and fixtures at non-resonant frequencies. Use an acceleration sensor to measure the amplitudes at non-resonant frequencies (such as 100 Hz, 300 Hz) multiple times, record the average amplitude, and select the average amplitude as the amplitude background level, such as 0.1 g. When the amplitude in the vibration spectrum state is greater than the amplitude noise level, it is marked as a residual standing wave (for example, the amplitude of 0.4 g at a vibration frequency of 150 Hz is greater than 0.1 g, so it is marked).

[0071] Extract 1000 amplitude values in the vibration spectrum state (one point every 0.01 seconds, for example, 0.4 g), calculate the phase of the residual standing wave. Taking 150 Hz as an example, multiply the amplitude of 0.4 g by the sine value (sin(2π×150×t), where t is the time, such as 0.001 seconds, 0.002 seconds, etc.), and sum up the 1000 amplitude values to obtain the sine component. For example, 0.4×sin(0.942)+0.39×sin(1.884)+...≈200 g. Multiply each amplitude value by the cosine value, that is, cos(2π×150×t), and sum up to obtain the cosine component. For example, 0.4×cos(0.942)+...≈50 g. Divide the sine component by the cosine component to get the phase of the residual standing wave as arctan(200÷50)≈0.2 radians (rad). Repeat the calculation of the phases of all residual standing waves and integrate them with the vibration spectrum state into a residual wave table, including vibration frequency, amplitude, and the phase of the residual standing wave. For example, 150 Hz, 0.4 g, 0.2 rad.

[0072] S4.5. Next, it is necessary to use a piezoelectric brake to calculate the voltage of the reverse waveform. Specifically, taking the residual standing wave of 150 Hz as an example, convert the amplitude of 0.4 g into the form of acceleration, that is, 0.4×9.8 = 3.92 meters per second squared (the amplitude of the reverse waveform is the same as that of the residual standing wave, which is 0.4 g); after adding π to the phase of the residual standing wave, obtain the reverse phase of the reverse waveform, that is, 0.2 radians + π≈3.34 radians, and then calculate the displacement of the reverse waveform, that is, divide the acceleration amplitude by the square of the angular frequency (the angular frequency is 2π×150≈942.477 radians per second), 3.92÷(942.477) 2 ≈4.4×10 -6 meters (i.e., 4.4 microns); assuming the sensitivity of the piezoelectric brake is 0.1 micron per volt, then the voltage of the reverse waveform is 4.4÷0.1 = 44 volts.

[0073] Integrate the voltage, vibration frequency, amplitude, and phase of the reverse waveform together to form reverse waveform parameters, such as 150 Hz, 0.4 g, 3.34 rad, 44 V.

[0074] S4.6. Generate a reverse waveform using the reverse waveform parameters and cancel the residual standing wave. Fix the piezoelectric actuator to the bottom of the automotive fastener bolt using high-strength adhesive, and at the same time connect the piezoelectric actuator to the signal generator. Input the reverse waveform parameters into the signal generator to drive the piezoelectric actuator to generate vibrations opposite to the residual standing wave, thereby canceling the residual standing wave. Taking a vibration frequency of 150 Hz as an example, the input parameters are an amplitude of 0.4 g (reverse waveform voltage of 44 volts), a frequency of 150 Hz, and a residual standing wave phase of 3.34 radians. Manually set the signal generator, that is, adjust the voltage knob to 44 volts, the frequency knob to 150 Hz, and the phase knob to 3.34 radians, and start the sine wave output. When the piezoelectric actuator receives the signal from the signal generator, it generates a displacement of 4.4 microns (44 volts × 0.1 micron per volt), which is opposite to the direction of the residual standing wave of 150 Hz (0.4 g, displacement of 4.4 microns). The generated sine waveform (e.g., 150 Hz, 44 volts, 3.34 radians) is the reverse waveform. Start the acceleration sensor, apply the 150 Hz reverse waveform, read the sensor display screen, and record the amplitude decrease of the automotive fastener, for example, from 0.4 g to 0.05 g. Organize the results of canceling the residual standing wave, handwrite a table named the stable vibration state report form, which includes the vibration frequency, reverse waveform voltage, and amplitude after canceling the residual standing wave, such as 150 Hz, 44 V, 0.05 g.

[0075] This embodiment also provides a monitoring system for an automotive fastener vibration test device, including: a data generation module, which sprays a photonic crystal thin film onto the automotive fastener, collects the optical wavelength distribution data on the surface of the photonic crystal thin film, and generates a wavelength shift data stream; An operation module, which calculates the strain value of the monitoring point of the automotive fastener using the wavelength shift data stream, draws a strain heat map and calculates the local strain gradient, sets a strain gradient threshold, and when the local strain gradient exceeds the strain gradient threshold, issues an audible and visual alarm signal and transmits it to the vibration table to activate the vibration table frequency reduction protection mechanism to obtain the operating state of the vibration table; A frequency identification module, which collects vibration signals and generates a vibration spectrogram, constructs an equivalent impedance network model and analyzes the vibration spectrogram to identify the parasitic resonance frequency points; A state generation module, which suppresses the band energy reflection in the parasitic resonance frequency points using a hydraulic damper to obtain a vibration spectrum state, generates a reverse waveform through a piezoelectric actuator, and uses the reverse waveform to cancel the residual standing wave in the vibration spectrum state, and outputs a stable vibration state report form.

[0076] This embodiment also provides a computer device, which is applicable to the monitoring method of an automotive fastener vibration testing device, and includes: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the monitoring method of the automotive fastener vibration testing device as proposed in the above embodiment.

[0077] This computer device can be a terminal, and this computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of this computer device is used to provide computing and control capabilities. The memory of this computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of this computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a carrier network, NFC (Near Field Communication), or other technologies. The display screen of this computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of this computer device can be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the outer shell of the computer device, or an external keyboard, a touchpad, or a mouse, etc.

[0078] This embodiment also provides a storage medium, on which a computer program is stored, and when this program is executed by a processor, it implements the monitoring method of the automotive fastener vibration testing device as proposed in the above embodiment; the storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM for short), Electrically Erasable Programmable Read-Only Memory (EEPROM for short), Erasable Programmable Read Only Memory (EPROM for short), Programmable Red-Only Memory (PROM for short), Read-Only Memory (ROM for short), magnetic memory, flash memory, a magnetic disk, or an optical disc.

[0079] In summary, the present invention: immediately triggers early warnings and protective measures when abnormal strain gradients are detected, effectively avoiding the risk of equipment damage caused by inaccurate suppression of resonance frequencies, thereby improving the safety and efficiency of testing. At the same time, the constructed equivalent impedance network model improves the accuracy of identifying parasitic resonance frequency points, solves the problem of inaccurate suppression of resonance frequencies, and also reduces unnecessary energy consumption and mechanical damage. By calculating the strain values at the monitoring points of automotive fasteners, the local strain of automotive fasteners is efficiently quantified, greatly improving the abnormal detection accuracy of the dynamic protection mechanism and making up for the lack of refined strain analysis in the existing monitoring methods for automotive fastener vibration testing equipment.

[0080] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A monitoring method for an automotive fastener vibration test device, characterized in that: including Spray the photonic crystal film onto the automotive fastener, collect the optical wavelength distribution data on the surface of the photonic crystal film, and generate a wavelength shift data stream; Calculate the strain value of the monitoring point of the automotive fastener using the wavelength shift data stream, draw a strain heat map and calculate the local strain gradient, set a strain gradient threshold, and when the local strain gradient exceeds the strain gradient threshold, send an audible and visual alarm signal to the vibration table and activate the vibration table frequency reduction protection mechanism to obtain the operating state of the vibration table; Collect vibration signals and generate a vibration spectrogram, construct an equivalent impedance network model and analyze the vibration spectrogram to identify parasitic resonance frequency points; Use a hydraulic damper to suppress the band energy reflection in the parasitic resonance frequency points to obtain a vibration spectrum state, generate a reverse waveform through a piezoelectric actuator, and use the reverse waveform to cancel the remaining standing waves in the vibration spectrum state to output a stable vibration state report form.

2. The monitoring method of the automotive fastener vibration test equipment according to claim 1, characterized in that: The generation of the wavelength shift data stream refers to using a laser interferometer to collect the optical wavelength distribution data on the surface of the photonic crystal film, and numbering the optical wavelength distribution data on the surface of the photonic crystal film in a spatial order to form monitoring points; Use the LabVIEW spectral processing suite to extract the wavelength peaks of each monitoring point and organize them to form a reflection spectrum database; Use an HR4000 spectrometer to collect the reflection spectrum data of the photonic crystal film to form a reflection spectrum data set, compare the reflection spectrum data set with the reflection spectrum database, calculate the wavelength shift amount and organize it into a wavelength shift data stream.

3. The monitoring method of the automotive fastener vibration test equipment according to claim 2, characterized in that: The calculation of the strain value of the monitoring point of the automotive fastener includes establishing a calibration curve, finding the wavelength shift amount closest to the wavelength shift data stream in the calibration curve, and converting the closest wavelength shift amount into the strain value of the monitoring point of the automotive fastener through linear interpolation.

4. The monitoring method of the vibration test equipment for automotive fasteners according to claim 3, characterized in that: The obtaining of the operating state of the vibration table refers to organizing the strain values of the monitoring points of the automotive fastener to form a strain value data set, and using a three-dimensional optical scanner to create a three-dimensional geometric coordinate file of the automotive fastener; Use MATLAB software to extract the three-dimensional coordinates of the three-dimensional geometric coordinate file, match the strain values in the strain value data set with the three-dimensional coordinates to form a comprehensive data set; Use a Python interpreter to simplify the three-dimensional coordinates in the comprehensive data set into two-dimensional plane coordinates, construct a two-dimensional grid, find the monitoring point closest to each grid point in the comprehensive data set and assign a strain value to generate a stress heat map; According to the stress heat map, calculate the local strain gradient values between adjacent monitoring points and organize them into a local strain gradient value table, set a strain gradient threshold, compare each local strain gradient value in the local strain gradient table with the strain gradient threshold, and output an exception record file; According to the exception record file, start the warning mechanism to send an audible and visual alarm signal, send the trigger instruction in the exception record file to the vibration table, and obtain the operating state of the vibration table after observing the change in the operating state of the vibration table.

5. The monitoring method of the vibration test equipment for automotive fasteners according to claim 4, characterized in that: The construction of the equivalent impedance network model refers to organizing the operating state of the vibration table into a vibration table operating state log file, and the vibration table operating state file includes the vibration frequency and amplitude; Create data input controls using LabVIEW software, record the vibration frequency and amplitude as excitation units, calculate the mass of the automotive fastener, the mass of the fixture, and the stiffness value of the automotive fastener, and label them as the automotive fastener mass unit, the fixture mass unit, and the automotive fastener stiffness unit respectively; Create connection controls and arrange all units in the order of vibration energy transfer to form an equivalent impedance network model.

6. The monitoring method of the automotive fastener vibration test equipment according to claim 5, characterized in that: The identified parasitic resonance frequency points refer to using an acceleration sensor to collect the vibration signals of the automotive fastener and the fixture to generate a vibration signal file; Perform Fourier transform processing on the vibration signal file, calculate the amplitude values of all vibration frequencies, and form a vibration spectrum diagram; Check the amplitude peaks in the vibration spectrum diagram, use the equivalent impedance network model to predict the theoretical amplitude peaks, set the amplitude difference threshold, calculate the difference between the amplitude peak and the theoretical amplitude peak and compare it with the amplitude difference threshold to identify the parasitic resonance frequency points.

7. The monitoring method of the vibration test equipment for automotive fasteners according to claim 6, characterized in that: The output of the stable vibration state report form refers to selecting a hydraulic damper as a suppressor, calculating the viscosity coefficient of the hydraulic damper and performing suppression verification to obtain the damping adjustment result; According to the damping adjustment result, apply a signal at a non-parasitic resonance frequency point to the automotive fastener and record the vibration frequency and amplitude of the automotive fastener to form a vibration spectrum state; Use the vibration spectrum state to identify the remaining standing waves, calculate the phase of the remaining standing waves, and at the same time use a piezoelectric actuator to calculate the voltage of the reverse waveform, and integrate the voltage of the reverse waveform, the vibration spectrum state, and the phase of the remaining standing waves to form reverse waveform parameters; Generate a reverse waveform using the reverse waveform parameters and cancel the remaining standing waves to obtain a stable vibration state report form.

8. A monitoring system for an automotive fastener vibration test device, based on the monitoring method for an automotive fastener vibration test device according to any one of claims 1 to 7, characterized in that: Including, A data generation module that sprays a photonic crystal thin film onto the automotive fastener, collects the optical wavelength distribution data on the surface of the photonic crystal thin film, and generates a wavelength shift data stream; An operation module that calculates the strain value of the monitoring point of the automotive fastener using the wavelength shift data stream, draws a strain heat map and calculates the local strain gradient, sets the strain gradient threshold, and when the local strain gradient exceeds the strain gradient threshold, issues an audible and visual alarm signal and transmits it to the vibration table to activate the vibration table frequency reduction protection mechanism to obtain the operating state of the vibration table; A frequency identification module that collects vibration signals and generates a vibration spectrum diagram, constructs an equivalent impedance network model and analyzes the vibration spectrum diagram to identify parasitic resonance frequency points; A state generation module that uses a hydraulic damper to suppress the band energy reflection in the parasitic resonance frequency points to obtain a vibration spectrum state, generates a reverse waveform through a piezoelectric actuator, and uses the reverse waveform to cancel the remaining standing waves in the vibration spectrum state and outputs a stable vibration state report form.

9. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the monitoring method of the automotive fastener vibration test device according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the monitoring method of the automotive fastener vibration test device according to any one of claims 1 to 7.

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