Bolt multidirectional load measuring method and system based on array ultrasonic waves

Abstract

The invention discloses a bolt multidirectional load measurement method and system based on array ultrasonic waves, and the method comprises the following steps: (1) axial load measurement calibration: carrying out the linear fitting of the longitudinal wave sound time difference of a central electrode under different axial loads, and building an axial load formula of the central electrode; axial load detection: calculating the axial load of the bolt to be detected according to the formula; (2) transverse load direction identification: fitting the function relationship between the angle of the edge electrode and the sound time difference as a sine function according to the sound time difference of the edge electrode at each angle under the action of the transverse load to be detected, obtaining the maximum value of the sine function, and identifying the transverse load direction according to the angle corresponding to the maximum value; (3) measuring and calibrating the size of the transverse load, and establishing a function of the difference value of the maximum sound time difference and the transverse load according to the difference value of the central electrode longitudinal wave sound time difference and the maximum longitudinal wave sound time difference; and transverse load detection: calculating the transverse load of the to-be-detected bolt according to the function.

Description

Technical Field

[0001] This invention belongs to the field of nondestructive testing technology, specifically relating to a method and system for measuring multi-directional loads on bolts based on array ultrasonic waves. Background Technology

[0002] Hydropower unit fasteners are frequently subjected to irregular vibrations, alternating loads, and impact loads, leading to problems such as bolt breakage or loosening. This significantly impacts the safe operation of the unit and, in severe cases, can cause collapse accidents. Therefore, it is essential to perform high-precision measurements on the bolts to meet the requirements for real-time monitoring of internal bolt stress, thereby enhancing the reliability and safety of hydropower unit operation.

[0003] In the field of bolt stress measurement, early research both domestically and internationally has made some progress. Among them, the ultrasonic method based on the principle of acoustoelasticity has been widely used in axial load measurement, but research on transverse load direction is relatively limited. The traditional ultrasonic longitudinal wave method mainly relies on the mathematical relationship between elastic stress and the longitudinal and transverse wave sound velocities of ultrasonic waves to detect bolts that are already tightened and cannot be calibrated by longitudinal wave acoustoelasticity. However, this method cannot effectively measure multi-directional loads. Current ultrasonic testing technology for bolts: a) can only measure stress in one direction and can only obtain one acoustic time data. It cannot simultaneously measure the magnitude and direction of a single load, let alone simultaneously measure loads in multiple directions on the bolt. It is limited to scenarios where the load direction is known, such as the process of applying preload to the bolt. However, during the service of a water turbine, the external environment will apply complex alternating loads to the bolt, so new stress measurement methods need to be developed; b) Generally, ultrasonic probes have only one electrode, which is placed in the central area of ​​the bolt head or bottom during measurement. When the bolt is subjected to transverse load, the central area of ​​the bolt is not subjected to tension and compression, and the acoustic time remains almost unchanged when a transverse load is applied. Therefore, a single central electrode in the ultrasonic sensor cannot measure the magnitude and direction of the transverse load. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method and system for measuring multi-directional loads of bolts based on array ultrasonic waves.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for measuring multi-directional load on bolts based on array ultrasonic waves includes a central electrode and multiple edge electrodes disposed on one end face of the bolt to be inspected. The central electrode is located at the center of the end face, and the multiple edge electrodes are arranged in a ring array along the edge of the end face. Both the central electrode and the edge electrodes are connected to sensors. The method includes the following steps: (1) Measurement of bolt axial load; (1.1) Calibration process; (a1) Apply gradient axial load to the bolt to be inspected and record the longitudinal wave acoustic time difference of the center electrode under different axial loads; (a2) Linear fitting was performed on the longitudinal wave acoustic time difference of the center electrode under different axial loads to establish the axial load formula of the center electrode; (1.2) Measurement process; The longitudinal wave time difference of the center electrode of the bolt to be inspected is measured to obtain the actual value. The axial load of the bolt to be inspected is calculated according to the axial load formula obtained in step (a2). (2) Identification of the transverse load direction of the bolt; (2.1) Apply actual axial and transverse loads to the bolt to be inspected to obtain the acoustic time difference of the edge electrodes at different angles; or, the bolt to be inspected can be rotated at a fixed angle to increase the acoustic time difference measurement values ​​at different orientations. (2.2) The acoustic time difference data of the edge electrodes at various angles under the above transverse load were analyzed, and it was found that the acoustic time difference data of the edge electrodes in the circumferential direction showed a sinusoidal function distribution law. (2.3) Fit the angle and acoustic time difference data of the edge electrode under the above transverse load according to the sine function to obtain the sine function of angle and acoustic time difference; according to the sine function of angle and acoustic time difference, obtain the maximum value of the sine function, and identify the transverse load direction according to the angle corresponding to the maximum value; (3) Measurement of the magnitude of the bolt's transverse load; (3.1) Calibration process; (b1) Apply the same axial load to the bolt to be inspected, and then apply a gradient transverse load to the bolt to be inspected. Record the longitudinal wave acoustic time difference of the center electrode and the edge electrode under different transverse loads. (b2) Based on the longitudinal wave acoustic time difference data of each edge electrode, that is, the longitudinal wave acoustic time difference data of each edge electrode presents a sinusoidal function distribution pattern, the maximum value of the sinusoidal function is found after fitting, and is recorded as the maximum longitudinal wave acoustic time difference. (b3) Calculate the difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference under different transverse loads, fit the difference with the transverse load, and establish a function of the maximum acoustic time difference and the transverse load. (3.2) Actual measurement process; The longitudinal wave time difference and the maximum longitudinal wave time difference of the center electrode of the bolt to be inspected are detected. The difference between the longitudinal wave time difference and the maximum longitudinal wave time difference is calculated. Then, based on the function of the maximum time difference difference obtained in step (b3) and the transverse load, the transverse load of the bolt to be inspected is calculated.

[0007] The above-mentioned bolt multi-directional load measurement method based on array ultrasound is further improved in that the lateral load direction of the bolt is: from the central electrode to the position of the angle corresponding to the maximum value of the fitted sine function.

[0008] The above-mentioned bolt multi-directional load measurement method based on array ultrasonic waves is further improved in step (a2), where the axial load formula of the central electrode is shown in equation (1). (1); In equation (1), The longitudinal wave acoustic time difference at the center electrode is expressed in nanoseconds (ns). This is the axial load, in kN. , These are calibration coefficients.

[0009] The above-mentioned bolt multi-directional load measurement method based on array ultrasonic waves is further improved in step (b3), where the function of the maximum acoustic time difference difference and the transverse load is as shown in equation (2). (2); In equation (2), This represents the difference between the longitudinal wave acoustic time difference at the center electrode and the maximum longitudinal wave acoustic time difference, expressed in nanoseconds (ns). This is a lateral load, measured in kN. , , The fitting coefficients are denoted as .

[0010] As a general technical concept, the present invention also provides a bolt multi-directional load measurement system based on array ultrasonic waves, used to perform the above-described bolt multi-directional load measurement method based on array ultrasonic waves, wherein the bolt multi-directional load measurement system based on array ultrasonic waves includes: The longitudinal wave acoustic time difference acquisition unit of the center electrode applies gradient axial load and transverse load to the bolt to be inspected, and records the longitudinal wave acoustic time difference of the center electrode under different axial loads, as well as the longitudinal wave acoustic time of the center electrode under different transverse loads. The edge electrode longitudinal wave acoustic time difference acquisition unit applies gradient axial load and transverse load to the bolt under inspection, and records the longitudinal wave acoustic time difference of the edge electrode under different axial loads and the longitudinal wave acoustic time of the edge electrode under different transverse loads. The axial load formula acquisition unit performs linear fitting on the longitudinal wave acoustic time difference of the center electrode under different axial loads to establish the axial load formula of the center electrode. The function acquisition unit for the maximum acoustic time difference and lateral load finds the maximum longitudinal wave acoustic time difference of the edge electrodes based on the longitudinal wave acoustic time difference data of each edge electrode; calculates the difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference under different lateral loads; fits the difference with the lateral load data to establish a function for the maximum acoustic time difference and lateral load. The transverse load direction identification unit fits the functional relationship between angle and sound time difference based on the distribution pattern of sound time difference at various angles under transverse load; based on the functional relationship between angle and sound time difference, it obtains the maximum value of the sine function, and identifies the transverse load direction based on the angle corresponding to the maximum value. The axial / lateral load acquisition unit obtains the axial load of the bolt under test according to the axial load formula, and obtains the lateral load of the bolt under test according to the function of the maximum acoustic time difference and the lateral load.

[0011] As a general technical concept, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for measuring multi-directional loads of bolts based on array longitudinal waves.

[0012] In this invention, the acoustic time difference is the difference between the time it takes for a longitudinal wave to be emitted and received under no-force conditions and the time it takes for a longitudinal wave to be emitted and received under force conditions.

[0013] Compared with the prior art, the advantages of the present invention are as follows: This invention provides a method for measuring multi-directional loads on bolts based on array ultrasonic waves. When measuring bolts subjected to multi-directional loads, it can simultaneously measure the magnitude of the axial and transverse loads, and accurately identify the direction of the transverse load. The measurement method of this invention comprises three parts: First, by setting a central electrode and multiple edge electrodes, the measurement accuracy of axial and transverse loads is higher under the combined action of multiple sensors. Second, based on the acoustic transit time difference of the edge electrodes at various angles under the transverse load being measured, a sine function is fitted to the relationship between the angle of the edge electrodes and the acoustic transit time difference. The maximum value of the sine function is obtained, and the transverse load direction is identified based on the angle corresponding to this maximum value. This identification method can accurately identify the transverse load direction. Third, based on the maximum longitudinal wave acoustic transit time difference and the longitudinal wave acoustic transit time difference of the central electrode, the difference between the maximum longitudinal wave acoustic transit time difference and the central electrode longitudinal wave acoustic transit time difference is extracted, and a function of the maximum acoustic transit time difference difference and the transverse load is plotted. The magnitude of the transverse load can be calculated using this function. The measurement method of this invention is applicable to bolt fasteners affected by irregular vibration, alternating loads, impact loads, etc. It can not only accurately measure the transverse and axial loads under complex alternating working conditions, but also identify the direction of the transverse load in real time, thereby completing a comprehensive judgment of the stress state of the bolt. Attached Figure Description

[0014] Figure 1 This is a structural diagram of the water and electricity bolt in Embodiment 1 of the present invention.

[0015] Figure 2 This is a schematic diagram showing the layout of the center electrode and edge electrode on the end face of the hydroelectric bolt in Embodiment 1 of the present invention.

[0016] Figure 3 This is a schematic diagram of the load applied to the hydroelectric bolt in Embodiment 1 of the present invention.

[0017] Figure 4 This is a graph showing the relationship between longitudinal wave acoustic time difference and axial load for the center electrode and edge electrode in Embodiment 1 of the present invention.

[0018] Figure 5 This is a graph showing the sinusoidal function curve relationship between the angle and acoustic time difference of the edge electrode in Embodiment 1 of the present invention.

[0019] Figure 6 This is a graph showing the relationship between longitudinal wave acoustic time difference and lateral load for each edge electrode during the calibration process of Embodiment 1 of the present invention.

[0020] Figure 7 This is a graph showing the relationship between longitudinal wave acoustic time difference and lateral load for the center electrode, sensor 1, and sensor 4 in Embodiment 1 of the present invention.

[0021] Figure 8 This is a graph showing the relationship between the maximum acoustic time difference (acoustic time difference interpolation between sensor 4 and the center sensor) and the lateral load in Embodiment 1 of the present invention.

[0022] Figure 9 This is the electrode angle-acoustic time difference fitting curve in the transverse load measurement of Example 1 of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0024] Example 1: A method for measuring multi-directional load on bolts based on array ultrasonic waves according to the present invention, for measuring multi-directional load on an M64 bolt with a length of 270mm, includes the following steps: (1) Fix the hydroelectric bolt to the clamp to facilitate the subsequent application of axial load. At the same time, the bolt connects two flanges as the connecting parts, which are restrained by nuts. Add a transverse load application device at the flange to facilitate the application of transverse load. Arrange a central electrode and multiple edge electrodes on one end face of the hydroelectric bolt. The central electrode is set at the center of the end face and is called the central sensor. The multiple edge electrodes are arranged in a ring array (circumferential arrangement) along the edge of the end face. The edge electrodes are respectively called sensor 1, sensor 2, sensor 3, sensor 4, sensor 5, and sensor 6. Both the central electrode and the edge electrodes are connected to sensors to facilitate the subsequent excitation and reception of ultrasonic signals, such as Figures 1-3 As shown.

[0025] (2) Measurement of bolt axial load (2.1) Calibration process (a1) Tensioning was performed using a tensioning machine to simulate the effects of different axial loads. Gradient axial loads of 50kN, 100kN, 150kN, 200kN, 250kN, and 300kN were applied to the hydroelectric bolts. Based on the acoustoelastic effect, the longitudinal wave acoustic time difference of the center electrode and the edge electrode under different axial loads was recorded. Taking sensor No. 1 as an example, the results are shown in Table 1.

[0026] Table 1. Longitudinal wave acoustic transit time data of the center electrode and edge electrode under different axial loads.

[0027] (a2) Linear fitting is performed on the longitudinal wave acoustic time difference of the center electrode or the edge electrode under different axial loads to establish the axial load formula of the center electrode or the edge electrode.

[0028] (2.2) Measurement process The longitudinal wave time difference of the center electrode of the plumbing bolt is measured to obtain the actual value. Based on the axial load formula for the center or edge electrode mentioned above, the axial load of the plumbing bolt is calculated. Figure 4 As shown.

[0029] Since the slopes of the longitudinal wave acoustic transit time-axial load relationship curves for all electrodes (including the center electrode and the edge electrodes) are almost the same, the axial load can be calculated using the axial load formula for any electrode. The axial load formula for the center electrode is shown in equation (1).

[0030] (1); In equation (1), The longitudinal wave acoustic time difference at the center electrode is expressed in nanoseconds (ns). This is the axial load, in kN. , is the calibration coefficient. Where, It is 0.789. It is 2.143.

[0031] (3) Identification of the transverse load direction of the bolt (3.1) Apply a specific axial load to the water and electricity bolt, and then apply a 2.5kN transverse load to the flange of the water and electricity bolt. Rotate the bolt counterclockwise 3 times with a gradient angle of 15°, and record the sound time difference at different angles. The results are shown in Table 2.

[0032] Table 2. Acoustic time difference data at various angles under a 2.5kN lateral load.

[0033] (3.2) Analysis of the acoustic time difference at various angles under a 2.5kN lateral load revealed that the acoustic time difference data of the edge electrode in the circumferential direction exhibits a sinusoidal distribution pattern, such as... Figure 5 As shown.

[0034] (3.3) Fit the angle and acoustic time difference data of the edge electrode under the action of 2.5kN transverse load according to the sine function to obtain the curve relationship of the sine function, that is, the sine function of angle and acoustic time difference, so as to find the maximum value of the sine function; the direction of the transverse load is: the direction from the center electrode to the angle corresponding to the maximum value.

[0035] Taking a lateral load of 2.5kN as an example, the sinusoidal function of angle versus acoustic time difference is shown in the following formula: TOF = 1.51sin[ ( [-82.61) / 194.7]-0.2215.

[0036] In this step, the specific axial load refers to the axial load under actual operating conditions.

[0037] (4) Measurement of the magnitude of the bolt transverse load (4.1) Calibration process (b1) Apply a specific axial load to the hydroelectric bolt, and then apply a gradient transverse load at the flange of the hydroelectric bolt, which are 5kN, 10kN, 15kN, 20kN and 25kN respectively. Collect the longitudinal wave acoustic time difference of the center electrode and the edge electrode under different transverse loads.

[0038] (b2) Based on the longitudinal wave acoustic transit time data of each edge electrode, find the maximum longitudinal wave acoustic transit time. In this calibration process, the lateral load is applied in the direction of sensor 4; therefore, the longitudinal wave acoustic transit time corresponding to sensor 4 is the maximum longitudinal wave acoustic transit time, and there is no need to further fit the direction of the maximum longitudinal wave acoustic transit time. Figure 6 As shown.

[0039] (b3) Calculate the difference between the longitudinal wave transit time of the center electrode and the maximum longitudinal wave transit time under different transverse loads. The results are shown in Table 3. Fit the difference to the transverse load to establish a function of the maximum transit time difference versus the transverse load, as shown in Table 3. Figure 8 As shown.

[0040] Table 3. Difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference under the same transverse load.

[0041] In this step, the function of the maximum acoustic time difference and the lateral load is shown in equation (2); (2); In equation (2), This represents the difference between the longitudinal wave acoustic time difference at the center electrode and the maximum longitudinal wave acoustic time difference, expressed in nanoseconds (ns). This is a lateral load, measured in kN. , , where are the fitting coefficients. It is 4.24. It is 5.87. It is 4.24.

[0042] (4.2) Actual measurement process Apply a transverse load of arbitrary magnitude and direction to the bolt under inspection, and record the longitudinal wave acoustic time difference of the center electrode and each edge electrode. Fit the angle and acoustic time difference data of the edge electrodes to a sine function to obtain a sine function of angle versus acoustic time difference. Find the maximum value of the sine function based on the angle versus acoustic time difference to obtain the maximum longitudinal wave acoustic time difference. Calculate the difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference. Then, based on the function of the maximum acoustic time difference difference and the transverse load, calculate the transverse load of the bolt under inspection, as follows: Figure 9 As shown.

[0043] Figure 4 This is a graph showing the relationship between the longitudinal wave acoustic time difference and axial load for the center electrode and edge electrode in Embodiment 1 of the present invention. Figure 4 It is known that by linearly fitting the longitudinal wave acoustic transit time of the center electrode or edge electrode under different axial loads, the axial load formula of the center electrode or edge electrode can be fitted, thereby accurately calculating the magnitude of the axial force. In this embodiment, the axial load test results of the hydroelectric bolt show that for every 1kN increase in axial load, the longitudinal wave acoustic transit time increases by 4.8ns.

[0044] Figure 5This is a graph showing the sinusoidal function curve relationship between the angle and acoustic time difference of the edge electrode in Embodiment 1 of the present invention. Under lateral load, the sinusoidal function fitting relationship between the angle of the circumferential array edge electrode and the acoustic time difference is used to find the angle where the maximum acoustic time difference occurs, i.e., the maximum value of the sinusoidal function. Figure 5 The present invention can accurately determine the lateral load direction, that is, the position from the location of the central electrode to the angle corresponding to the maximum value. Figure 6 This is a graph showing the relationship between longitudinal wave acoustic time difference and lateral load for each edge electrode during the calibration process of Embodiment 1 of the present invention. Figure 6 To obtain the acoustic time difference data of each sensor in a layout of six circular array sensors, with the lateral load applied in the direction of sensor number 4. Figure 6 It can be seen that sensor number 4 has the largest acoustic time difference.

[0045] Figure 7 This is a graph showing the relationship between longitudinal wave acoustic time difference and lateral load for the center electrode, sensor 1, and sensor 4 in Embodiment 1 of the present invention. Figure 8 This is a graph showing the relationship between the maximum acoustic time difference (interpolation of acoustic time difference between sensor 4 and the center sensor) and the lateral load in Embodiment 1 of the present invention. (Combined with...) Figure 7 and Figure 8 It can be seen that the rate of change of longitudinal wave acoustic time difference varies with the increase of lateral load. Furthermore, the difference between longitudinal wave acoustic time difference of sensor 4 and center sensor was extracted, and data fitting was performed to obtain the function of the maximum acoustic time difference of sensor 4 and the difference between acoustic time difference of center sensor and lateral load.

[0046] The above describes the calibration of the lateral load for this bolt specification and when the distance between the edge electrode and the center is 20mm. This calibration is required for bolts of different specifications and for different edge electrode distances when using this method to detect the direction and magnitude of the lateral load. After calibration, lateral loads of any magnitude and direction can be applied to the bolt, and the obtained electrode acoustic time difference data are shown in Table 4.

[0047] Table 4 Measured Electrode Acoustic Time Difference Data

[0048] Substituting the acoustic time of the center electrode, 480 ns, into equation (1), ,in, It is 0.789. The value is 2.143, calculated as follows: =602kN, therefore the axial load at this time is 602kN.

[0049] Figure 9This is the electrode angle-acoustic time difference fitting curve in the transverse load measurement of Example 1 of the present invention. Figure 9 To apply a transverse load in any direction, the sinusoidal function relationship between the fitted angle and the acoustic time difference was obtained, with electrode 1 as 0° and counterclockwise as the positive direction. The angle with the maximum acoustic time difference was found to be 272°. Therefore, the transverse load direction can be determined to be along the center electrode pointing towards 272°. Based on the acoustic time difference of 546 ns at the 272° angle and 480 ns at the center electrode, the difference is 66 ns. Substituting this into the functional relationship between the maximum acoustic time difference and the transverse load in equation (2), the transverse load can be calculated to be 16.63 kN.

[0050] The present invention also provides a bolt multi-directional load measurement system based on array ultrasonic waves, used to perform the above-described bolt multi-directional load measurement method based on array ultrasonic waves, the bolt multi-directional load measurement system based on array ultrasonic waves comprising: The longitudinal wave acoustic time difference acquisition unit of the center electrode applies gradient axial load and transverse load to the bolt to be inspected, and records the longitudinal wave acoustic time difference of the center electrode under different axial loads, as well as the longitudinal wave acoustic time of the center electrode under different transverse loads. The edge electrode longitudinal wave acoustic time difference acquisition unit applies gradient axial load and transverse load to the bolt under inspection, and records the longitudinal wave acoustic time difference of the edge electrode under different axial loads and the longitudinal wave acoustic time of the edge electrode under different transverse loads. The axial load formula acquisition unit performs linear fitting on the longitudinal wave acoustic time difference of the center electrode under different axial loads to establish the axial load formula of the center electrode. The function acquisition unit for the maximum acoustic time difference and lateral load finds the maximum longitudinal wave acoustic time difference of the edge electrodes based on the longitudinal wave acoustic time difference data of each edge electrode; calculates the difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference under different lateral loads; fits the difference with the lateral load data to establish a function for the maximum acoustic time difference and lateral load. The transverse load direction identification unit fits the functional relationship between angle and sound time difference based on the distribution pattern of sound time difference at various angles under transverse load; based on the functional relationship between angle and sound time difference, it obtains the maximum value of the sine function, and identifies the transverse load direction based on the angle corresponding to the maximum value. The axial / lateral load acquisition unit obtains the axial load of the bolt under test according to the axial load formula, and obtains the lateral load of the bolt under test according to the function of the maximum acoustic time difference and the lateral load.

[0051] The bolt multi-directional load measurement method based on array ultrasonic waves of the present invention is applicable to bolts with base materials such as stainless steel, aluminum, cemented carbide, high-speed steel, and titanium, and is not limited thereto.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for measuring multi-directional load on bolts based on array ultrasonic waves, comprising a central electrode and multiple edge electrodes disposed on one end face of the bolt to be inspected, wherein the central electrode is disposed at the center of the end face, and the multiple edge electrodes are distributed in a ring array along the edge of the end face, and both the central electrode and the edge electrodes are connected to sensors, characterized in that, Includes the following steps: (1) Measurement of bolt axial load; (1.1) Calibration process; (a1) Apply gradient axial load to the bolt to be inspected and record the longitudinal wave acoustic time difference of the center electrode under different axial loads; (a2) Linear fitting was performed on the longitudinal wave acoustic time difference of the center electrode under different axial loads to establish the axial load formula of the center electrode; (1.2) Measurement process; The longitudinal wave time difference of the center electrode of the bolt to be inspected is measured to obtain the actual value. The axial load of the bolt to be inspected is calculated according to the axial load formula obtained in step (a2). (2) Identification of the transverse load direction of the bolt; (2.1) Apply actual axial and transverse loads to the bolt to be inspected to obtain the acoustic time difference of the edge electrodes at different angles; or, the bolt to be inspected can be rotated at a fixed angle to increase the acoustic time difference measurement values ​​at different orientations. (2.2) The acoustic time difference data of the edge electrodes at various angles under the above transverse load were analyzed, and it was found that the acoustic time difference data of the edge electrodes in the circumferential direction showed a sinusoidal function distribution law. (2.3) Fit the angle and acoustic time difference data of the edge electrode under the above transverse load according to the sine function to obtain the sine function of angle and acoustic time difference; according to the sine function of angle and acoustic time difference, obtain the maximum value of the sine function, and identify the transverse load direction according to the angle corresponding to the maximum value; (3) Measurement of the magnitude of the bolt's transverse load; (3.1) Calibration process; (b1) Apply the same axial load to the bolt to be inspected, and then apply a gradient transverse load to the bolt to be inspected. Record the longitudinal wave acoustic time difference of the center electrode and the edge electrode under different transverse loads. (b2) Based on the longitudinal wave acoustic time difference data of each edge electrode, that is, the longitudinal wave acoustic time difference data of each edge electrode presents a sinusoidal function distribution pattern, the maximum value of the sinusoidal function is found after fitting, and is recorded as the maximum longitudinal wave acoustic time difference. (b3) Calculate the difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference under different transverse loads, fit the difference with the transverse load, and establish a function of the maximum acoustic time difference and the transverse load. (3.2) Actual measurement process; The longitudinal wave time difference and the maximum longitudinal wave time difference of the center electrode of the bolt to be inspected are detected. The difference between the longitudinal wave time difference and the maximum longitudinal wave time difference is calculated. Then, based on the function of the maximum time difference difference obtained in step (b3) and the transverse load, the transverse load of the bolt to be inspected is calculated.

2. The bolt multi-directional load measurement method based on array ultrasonic waves according to claim 1, characterized in that, The lateral load direction of the bolt is: from the center electrode to the position of the angle corresponding to the maximum value of the fitted sine function.

3. The bolt multi-directional load measurement method based on array ultrasonic waves according to claim 1 or 2, characterized in that, In step (a2), the axial load formula of the central electrode is shown in equation (1); （1）； In equation (1), The longitudinal wave acoustic time difference at the center electrode is expressed in nanoseconds (ns). This is the axial load, in kN. , These are calibration coefficients.

4. The bolt multi-directional load measurement method based on array ultrasonic waves according to claim 1 or 2, characterized in that, In step (b3), the function of the maximum acoustic time difference and the lateral load is shown in equation (2); （2）； In equation (2), This represents the difference between the longitudinal wave acoustic time difference at the center electrode and the maximum longitudinal wave acoustic time difference, expressed in nanoseconds (ns). This is a lateral load, measured in kN. , , represents the fitting coefficient.

5. A bolt multi-directional load measurement system based on array ultrasonic waves, characterized in that, For performing the bolt multi-directional load measurement method based on array ultrasonic waves as described in any one of claims 1 to 4, the bolt multi-directional load measurement system based on array ultrasonic waves comprises: The longitudinal wave acoustic time difference acquisition unit of the center electrode applies gradient axial load and transverse load to the bolt to be inspected, and records the longitudinal wave acoustic time difference of the center electrode under different axial loads, as well as the longitudinal wave acoustic time of the center electrode under different transverse loads. The edge electrode longitudinal wave acoustic time difference acquisition unit applies gradient axial load and transverse load to the bolt under inspection, and records the longitudinal wave acoustic time difference of the edge electrode under different axial loads and the longitudinal wave acoustic time of the edge electrode under different transverse loads. The axial load formula acquisition unit performs linear fitting on the longitudinal wave acoustic time difference of the center electrode under different axial loads to establish the axial load formula of the center electrode. The function acquisition unit for the maximum acoustic time difference and lateral load finds the maximum longitudinal wave acoustic time difference of the edge electrodes based on the longitudinal wave acoustic time difference data of each edge electrode; calculates the difference between the longitudinal wave acoustic time difference of the center electrode and the maximum longitudinal wave acoustic time difference under different lateral loads; fits the difference with the lateral load data to establish a function for the maximum acoustic time difference and lateral load. The transverse load direction identification unit fits the functional relationship between angle and sound time difference based on the distribution pattern of sound time difference at various angles under transverse load; based on the functional relationship between angle and sound time difference, it obtains the maximum value of the sine function, and identifies the transverse load direction based on the angle corresponding to the maximum value. The axial / lateral load acquisition unit obtains the axial load of the bolt under inspection according to the axial load formula, and obtains the lateral load of the bolt under inspection according to the function of the maximum acoustic time difference and the lateral load.

6. A computer-readable storage medium storing a computer program thereon, characterized in that, When the computer program is executed by the processor, it implements the bolt multi-directional load measurement method based on array longitudinal waves as described in any one of claims 1 to 4.

Images