A method for spatial stress detection of steel components based on transverse wave transmission and three reception.

Abstract

This invention relates to a method for detecting spatial stress in steel components based on a transverse wave transmission and three-reception system. The method involves obtaining a replica specimen of the in-service steel structure component to be tested; conducting a transverse wave transmission and three-reception calibration experiment on the replica specimen to determine the spatial stress detection coefficient matrix and obtain a detection formula for spatial stress information; defining a detection area and conducting a transverse wave transmission and three-reception spatial stress detection experiment on the in-service steel component within the detection area, acquiring ultrasonic time-domain signals at three receiving positions; performing spectral analysis on the obtained time-domain signals to identify the quasi-transverse wave acoustic time difference changes and quasi-longitudinal wave acoustic time difference changes along the three propagation paths under spatial stress conditions, and substituting these into the spatial stress detection formula for the replica specimen to obtain the spatial stress information of the steel component. This method can directly detect the spatial stress information of in-service steel plate components of different materials and thicknesses, and the testing instrument is easy to install, low-cost, and readily implemented.

Description

Technical Field

[0001] This invention belongs to the field of non-destructive testing of stress in steel structure components, and particularly relates to a spatial stress testing method for steel components based on a transverse wave transmission and reception method. Background Technology

[0002] With the development of steel structure forms in my country in recent years, a large number of steel components and nodes have become increasingly large and complex. The increase in component size and node volume renders the plane stress assumption inapplicable. In addition to in-plane stress, steel plate components are also subject to out-of-plane stress, meaning the components are actually under spatial stress. Simultaneously, the increased node volume renders conventional spatial mechanical modeling methods for nodes inapplicable, and existing stress distribution laws and cross-sectional deformation theories no longer hold true. Conventional design methods do not consider deformation release caused by non-planar cross-sectional deformation, thus overestimating the stiffness of components, nodes, and even the entire structural system, leading to unsafe design results. Therefore, detecting the internal spatial stress of steel plate components plays a crucial role in structural engineering research, safe construction, and sustainable operation.

[0003] Currently, neither structural health monitoring nor stress-destructive testing and stress-nondestructive testing have achieved the ability to detect absolute stress within the internal space of steel plates. Compared with other stress detection methods, ultrasonic methods have unique advantages such as strong penetration, rich information carrying capacity, and small, portable equipment. Furthermore, numerous studies have shown that the time-domain and frequency-domain signals of ultrasonic waves in the unidirectional / planar stress field of metallic materials are correlated with the stress of the component, which theoretically provides a possibility for nondestructive testing of absolute spatial stress. However, due to the complexity of spatial stress, using ultrasound to detect absolute spatial stress within steel plate components remains challenging. For example, the specific relationship between ultrasonic signals and spatial stress is still unclear. Moreover, due to the complexity of spatial stress, more stress-related ultrasonic information is needed, and commonly used sensor arrangements and signal processing methods are no longer sufficient to meet the requirements for spatial stress detection. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the aforementioned problems in the prior art, this invention provides a method for detecting spatial stress information of steel components based on a transverse wave transmitter and receiver, enabling non-destructive testing of spatial stress information of in-service steel structural components.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] A method for detecting spatial stress in steel components based on a transverse wave transmission and reception system includes the following steps:

[0009] S1. Obtain a replica of the in-service steel component to be tested;

[0010] S2. Perform unidirectional loading and transverse wave one-transmitter-three-receiver experiments on the replicated specimen to determine the spatial stress detection coefficient matrix and obtain the spatial stress detection formula.

[0011] S3. Determine the detection area, and conduct a transverse wave one-transmitter-three-receiver spatial stress detection experiment on the in-service steel components within the detection area to obtain ultrasonic time-domain signals at three receiving positions.

[0012] S4. Perform spectral analysis on the captured time-domain signal, extract the quasi-transverse wave acoustic time difference change and the quasi-longitudinal wave acoustic time difference change, substitute them into the spatial stress detection formula of the replicated specimen, and obtain the spatial stress information of the steel component.

[0013] Preferably, the replicated specimen has the same thickness, material, and strength as the original steel component, but is scaled down proportionally.

[0014] Preferably, step S2 includes the following sub-steps:

[0015] S21. Construct a hardware system for detecting spatial stress information of steel components;

[0016] S22. Apply uniaxial compressive stress to the replica specimen in stages along the height direction, with a stress gradient of 7.5 MPa. Maintain each stress gradient for a period of time to carry out ultrasonic tests.

[0017] S23. Apply uniaxial compressive stress to the replicated specimen again along the length direction, with a stress gradient of 7.5 MPa. Maintain each stress gradient for a period of time to carry out the ultrasonic test.

[0018] S24. During the holding time of each stress gradient, ultrasonic transverse waves are emitted and received at the selected calibration location, and time-domain signals at the three receiving locations under the changed stress state are collected and stored.

[0019] S25. Perform spectrum analysis on the acquired time-domain signal, extract the quasi-transverse wave band, and extract the quasi-transverse wave acoustic time difference change at 1.2MHz frequency using the amplitude spectrum and phase spectrum of the quasi-transverse wave. Extract the quasi-longitudinal wave band and extract the quasi-longitudinal wave acoustic time difference change at 1.2MHz frequency using the phase spectrum of the quasi-longitudinal wave.

[0020] S26. Substitute the obtained quasi-transverse wave acoustic time difference change and quasi-longitudinal wave acoustic time difference into the spatial stress information detection formula, and determine the spatial stress detection coefficient matrix N through data fitting and parameter calculation.

[0021] Preferably, the steel component spatial stress information detection hardware system includes: an ultrasonic signal transmitter and receiver, a transverse wave sensor group with one transmitter and three receivers, a digital oscilloscope, and a steel component stress loading and controller;

[0022] Among them, the one-transmitter-three-receiver transverse wave sensor group includes four identical ultrasonic transverse wave sensors with a diameter of 9mm, a center frequency of 5MHz, a main frequency range of 0~10MHz, and the incident transverse wave is a multi-frequency coupled simple harmonic pulse wave.

[0023] The stress loading and controller is an electro-hydraulic servo universal testing machine with a maximum pressure of 1000 kN.

[0024] Preferably, when applying uniaxial compressive stress to the replica specimen step by step, the maximum stress does not exceed the yield stress of the specimen material, so that the specimen is always in an elastic state.

[0025] Preferably, ultrasonic transverse waves are transmitted and received at the selected calibration location. The transmitting and receiving sensors are placed vertically in a parallel transmitting and receiving mode 1. Transverse wave pulses are transmitted, and three sets of received time-domain signals are collected and stored.

[0026] Rotate the transverse wave transmitting sensor by π / 2 angle and place it horizontally. At this time, the transmitting sensor and the receiving sensor are in the vertical transmission and reception mode of mode 2. Transmit transverse wave pulses, collect and store three sets of received time domain signals.

[0027] Preferably, the quasi-transverse wave band is selected, and the amplitude spectrum function of the quasi-transverse wave received by mode 1 is:

[0028]

[0029] The amplitude spectrum function of the quasi-transverse wave received by method 2 is:

[0030]

[0031] The phase spectrum function of the quasi-transverse wave received by method 1 is:

[0032]

[0033] The phase spectrum function of the quasi-transverse wave received by method 2 is:

[0034]

[0035] Selecting the quasi-P-wave band, the phase spectrum function of the quasi-P-wave received by mode 2 is:

[0036]

[0037] Where f is the ultrasonic frequency, L i φ represents the propagation distance of an ultrasonic wave. iThe polarization angle of the quasi-transverse wave is represented by i = 1, 2, 3, and the superscripts / / and ⊥ represent transmission / reception mode 1 and mode 2, respectively; L r and φ r These represent the amplitude and phase of the received signal, respectively, and can be obtained from the time-domain signal after Fourier transform.

[0038] The acoustic time difference and polarization angle of the quasi-transverse wave are extracted using the amplitude and phase spectra of the quasi-transverse wave received in transmission / reception modes 1 and 2, respectively:

[0039]

[0040] The acoustic time variation of the quasi-longitudinal wave is extracted using the phase spectrum of the quasi-longitudinal wave received by transceiver mode 2, as follows:

[0041]

[0042] Where T0 is a constant term, and in the above formula, f = 1.2MHz.

[0043] Preferably, the formula for detecting spatial stress information is:

[0044]

[0045] Where, σ 11 , σ 22 , σ 33 , τ 12 , τ 13 , τ 23 For the six spatial stress components, σ 11 , σ 22 , σ 33 These are the normal stresses τ in the length, height, and thickness directions of the steel plate member, respectively. 12 For the shear stress within the plate, τ 13 and τ 23 For the two external shear stresses of the plate; N is the stress detection coefficient matrix, containing 36 stress detection coefficients o1~z3 related to the component material and thickness, and the frequency and propagation path of the ultrasonic waves; (Δt qS ) i Let Δt be the change in acoustic time difference between two quasi-transverse waves propagating inside the component. qP ) i Let i = 1, 2, 3 represent the change in quasi-longitudinal wave acoustic time propagating inside the component. The subscripts i = 1, 2, 3 represent three receiving sensors. The change here refers to the change in quasi-transverse wave acoustic time difference and quasi-longitudinal wave acoustic time under spatial stress state relative to the quasi-transverse wave acoustic time difference and quasi-longitudinal wave acoustic time under zero stress state. The expression is as follows:

[0046]

[0047] Among them, tqS1 t qS2 t qSP Let qS1 and qS2 represent the propagation of two quasi-transverse waves qS1 and qS2, and a quasi-longitudinal wave qP, respectively, under spatial stress conditions. The superscript 0 indicates the zero-stress state. These represent the corresponding acoustic times under zero stress conditions;

[0048] The quasi-transverse wave acoustic time difference change (Δt) under each stress state qS ) i Quasi-longitudinal wave acoustic time change (Δt) qP ) i Substituting into the spatial stress information detection formula, the stress detection coefficient matrix N can be determined through multivariate linear fitting and parameter calculation.

[0049] Preferably, step S3 includes the following sub-steps:

[0050] S31. Select a one-transmitter-three-receiver detection position in the area to be detected, and inject ultrasonic transverse waves in transmitter-receiver mode 1 to collect and store three sets of received ultrasonic time domain signals.

[0051] S32, a rotating transmitting sensor, re-injects a transverse wave in transmit / receive mode 2, and collects and stores three sets of received ultrasonic time-domain signals.

[0052] (III) Beneficial Effects

[0053] The beneficial effects of this invention are as follows: The method for detecting spatial stress information of steel components based on transverse wave transmission and reception provided by this invention has the following beneficial effects:

[0054] (1) The method of the present invention can realize non-destructive testing of spatial stress of in-service steel plate components of different materials and thicknesses. It is simple to operate, low in cost, and has certain engineering application value.

[0055] (2) The method of the present invention uses a frequency of 1.2MHz as the detection frequency and utilizes the amplitude and phase characteristics of the received signal to identify the quasi-transverse wave velocity difference and the quasi-longitudinal wave velocity difference, which has high sensitivity.

[0056] (3) The method of the present invention utilizes a sensor arrangement of one transmitter and three receivers to directly separate spatial stress, and can detect six spatial stress components with high accuracy.

[0057] In summary, the non-destructive testing method for spatial stress information of steel components based on transverse wave transmission and reception proposed in this invention enables non-destructive testing of spatial stress in in-service steel plate components of different materials and thicknesses. The testing process is simple, the testing instruments are easy to install, low in cost, and easy to implement. It can be used for spatial stress testing of internal steel structure plate components under construction and already built, as well as for spatial stress testing of other metal plate components. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the establishment of rectangular coordinate axes and trirefringence of transverse waves in this invention;

[0059] Figure 2 This is a schematic diagram of the arrangement of the one-transmitter, three-receiver shear wave sensor in this invention;

[0060] Figure 3 This is a schematic diagram of the spatial stress information detection system for steel components constructed in this invention;

[0061] Figure 4 This is the transceiver mode 1 of the transverse wave sensor group in this invention;

[0062] Figure 5 This is the second transceiver method of the transverse wave sensor group in this invention;

[0063] Figure 6 These are two unidirectional compression methods for steel plate detection coefficient calibration in this embodiment of the invention;

[0064] Figure 7 This refers to the positioning point of the steel plate specimen in the embodiment of the present invention, which is the location of the three-point calibration after one launch.

[0065] Figure 8 This is a time-domain diagram of three sets of ultrasonic signals received by the Q235b steel plate in mode 1 in an embodiment of the present invention;

[0066] Figure 9 This is a time-domain diagram of three sets of ultrasonic signals received by the Q235b steel plate via method 2 in an embodiment of the present invention;

[0067] Figure 10 This is the amplitude spectrum of the quasi-transverse wave signal received in two ways at the O3 receiving position in the Q235b steel plate in this embodiment of the invention;

[0068] Figure 11 This is the phase spectrum of the quasi-transverse wave signal received at the O3 receiving position in the Q235b steel plate in this embodiment of the invention through two methods;

[0069] Figure 12 This is the phase spectrum of the quasi-longitudinal wave signal received by mode 2 at the O3 receiving position in the Q235b steel plate in this embodiment of the invention;

[0070] Figure 13 This is the establishment of the non-uniform spatial stress field and finite element stress cloud map of the steel plate in the embodiments of the present invention;

[0071] Figure 14 These are the four detection areas of the steel plate in this embodiment of the invention. Detailed Implementation

[0072] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0073] In this embodiment, the principle of the spatial stress detection method for steel components based on a one-wave-transmitter-three-receiver transverse wave is as follows:

[0074] Ultrasonic transverse waves propagating within orthotropic materials do not propagate along the principal axis of symmetry. Instead, they propagate along an oblique path at a certain angle to the principal axis of symmetry within the component. In this case, the transverse wave decomposes into a quasi-longitudinal wave qP and two quasi-transverse waves qS1 and qS2. The particle vibration directions of these three wave components are neither parallel nor perpendicular to the wave propagation direction. The particle vibration direction of wave qP forms a small angle with the wave propagation direction, approaching parallelism. Similarly, the particle vibration direction of the quasi-transverse wave is approximately perpendicular to the wave propagation direction. Figure 1 As shown, under the influence of spatial stress, the wave velocity variations of quasi-longitudinal wave qP and quasi-transverse waves qS1 and qS2 are all different.

[0075] The processed steel plate material is considered to be a weakly orthogonal anisotropic material, and a spatial rectangular coordinate system is established as follows: Figure 1 As shown, O represents the position of the transmitting sensor. The sensor is arranged with one transmitter and three receivers as follows. Figure 2 As shown. The thickness of the component is l0, and the transmitting point O and the receiving point O are... i Both are located in the x1Ox3 plane, from the transmitting point O to the receiving point O i The straight-line distance is L i From transmitter point O to receiver point O i The horizontal distance is l i l0, L i With l i The Pythagorean theorem applies between them. Also, L... i The angle between the x1 and the positive x1 direction is β. i (π>β i >0), where i = 1, 2, 3, representing three propagation paths. For example... Figure 1 As shown, the incident transverse wave will decompose into a quasi-longitudinal wave qP and two quasi-transverse waves qS1 and qS2. Figure 1 η in i φ represents the polarization angle of the quasi-longitudinal wave. i Indicates along OO i The polarization angle of a path-propagating quasi-transverse wave.

[0076] The incident wave is a simple harmonic pulse wave. The transverse pulse can be viewed as a superposition of multiple resonant waves of different frequencies, resulting in a relatively complex waveform that includes various sine or cosine waves of different frequencies. For a single-frequency simple harmonic wave, its time-domain expression is:

[0077]

[0078] Where u0(t) represents the time-domain representation of the vibration of the vibration source O, A represents the amplitude of the ultrasonic transverse wave pulse, and t represents the vibration time of the vibration source. denoted by f, which represents the initial phase of the ultrasonic transverse wave pulse, and f represents the frequency.

[0079] After triple refraction, the incident shear wave is decomposed into three wave components along each path. Two special sensor transmission and reception methods are employed: First, the transmitting shear wave sensor is positioned along the positive x2 axis, and the three receiving shear wave sensors are positioned along the positive x2 axis, in a parallel transmission and reception configuration (Method 1); second, the transmitting shear wave sensor is positioned along the positive x1 axis, and the three receiving shear wave sensors are positioned along the positive x2 axis, in a perpendicular transmission and reception configuration (Method 2). Methods 1 and 2 are as follows... Figure 4 and Figure 5 As shown.

[0080] All wave components propagate to O along different paths at their respective speeds. i The signals are received by the sensor. After Fourier transform and necessary mathematical derivation, the amplitude and phase spectra of the quasi-transverse and quasi-longitudinal waves received in the two ways are obtained as follows:

[0081] The formula for the quasi-transverse wave amplitude spectrum is:

[0082]

[0083]

[0084] The formula for the quasi-transverse wave phase spectrum is:

[0085]

[0086]

[0087] The formula for the phase spectrum of the qP wave is:

[0088]

[0089] Where the superscripts / / and ⊥ represent transmission and reception mode 1 and mode 2, respectively; L r and φ r These represent the amplitude and phase of the received signal, respectively. These represent the qS1, qS2, and qP waves along OO, respectively. i The propagation time of sound along a path.

[0090] Solving for the polarization angle φ using a combination of equations i

[0091]

[0092] Solve the simultaneous equations to determine the change in acoustic time difference Δt between waves qS1 and qS2. qS

[0093]

[0094] Solve simultaneously for the change in acoustic time Δt during the propagation of wave qP. qP

[0095]

[0096] in, These represent the propagation times of the qS1, qS2, and qP waves along a single path under zero stress conditions, respectively.

[0097] According to the principle of acoustoelasticity, the Christoffel equations for the qS1, qS2, and qP waves are as follows:

[0098]

[0099]

[0100]

[0101] Among them, G ij The acoustic tensor related to the component material and the stress it is subjected to; β i (π>β i >0) is the azimuth angle of the propagation path, which is the angle between the propagation path and the positive x1 direction; V qS1 V qS2 and V qP They represent along OO respectively i Phase velocities of wave qS1, wave qS2, and wave qP propagation along the path.

[0102] Solving the fundamental equations of acoustic elasticity along the three propagation paths, we can express the wave speed information by dividing the propagation distance by the propagation time:

[0103]

[0104]

[0105] After necessary mathematical derivation and simplification, the spatial strain-acoustic time constitutive relation can be obtained:

[0106]

[0107] Where M is the spatial stress detection coefficient matrix, which contains thirty spatial strain detection coefficients a1 to k3 that are related to the material's density, second and third elastic coefficients, propagation direction, and ultrasonic speed.

[0108] By converting strain into stress using Hooke's law, we obtain the spatial stress-acoustic time constitutive relation:

[0109]

[0110] Where N is the spatial stress detection coefficient matrix, containing thirty-six coefficients related to the material's density, second and third elastic coefficients, propagation direction, and ultrasonic velocity, and spatial strain detection coefficients o1 to z3. The coefficient matrices N and M satisfy Hooke's Law, as shown below:

[0111]

[0112] Where C is the elastic coefficient matrix, and λ and μ are the Lamé constants of the material.

[0113] The values ​​of all detection coefficients were determined by calibration experiments and coefficient calculations.

[0114] Based on the above theoretical derivation, the implementation process of this method can be summarized into four main steps. The first step is to replicate the in-service steel plate component. The second step is to use a steel plate stress detection system to determine all detection coefficient values ​​of the replicated component at a frequency of 1.2MHz through calibration experiments and coefficient calculations, thereby determining the spatial stress-acoustic time constitutive relationship of the steel plate to be tested. The third step is to determine the detection area of ​​the in-service steel plate component, conduct a transverse wave one-transmit and three-receive experiment, and obtain the quasi-transverse wave and quasi-longitudinal wave time-domain signals. The fourth step is to perform spectral analysis on the captured time-domain signals, extract the quasi-transverse wave and quasi-longitudinal wave acoustic time variations on the three propagation paths at 1.2MHz using amplitude and phase spectra, and substitute them into the spatial stress-acoustic time constitutive relationship to obtain the magnitude of each stress component of the spatial stress in the in-service steel plate component. The implementation process of the four main steps of this method is as follows:

[0115] The first step is to replicate in-service steel structural components: In-service steel components are generally not disassembled, and this method requires understanding the spatial stress-acoustic time constitutive relationship of the in-service steel components. Therefore, a replica component with the same material and thickness as the in-service steel component is selected, which can be scaled down to laboratory size. The test coefficients are then calibrated on the replica specimen.

[0116] The second step involves conducting unidirectional loading and transverse wave one-transmitter-three-receiver experiments on the replicated specimen to determine all detection coefficients. The specific steps for this step are as follows:

[0117] (1) Establish a hardware system for detecting spatial stress information of steel components, such as Figure 3 As shown, it includes: an ultrasonic signal generator, an ultrasonic shear wave transmitter and receiver sensor group, a digital oscilloscope, a steel component stress loading and controller, and a computer for signal processing. Among them, the four shear wave sensors in the ultrasonic shear wave transmitter and receiver sensor group are the same type of shear wave sensor.

[0118] (2) Determine the calibration position and subject the specimen to uniform unidirectional pressure in both directions, such as... Figure 6 As shown, in each loading direction, a stress gradient of 7.5 MPa is used. Each gradient stress is maintained for a period of time to carry out the transverse wave one-wave-three-wave-receive experiment. Throughout the entire compression process, the specimen remains in an elastic state.

[0119] (3) During the holding time of each stress gradient, ultrasonic signals are transmitted and received at the calibrated position in transmit and receive mode 1, and three sets of time domain signals are collected and stored. Then the direction of the transmitting sensor is adjusted, and ultrasonic signals are transmitted and received in transmit and receive mode 2, and three sets of time domain signals are collected and stored.

[0120] (4) Extract the time-domain signals of the quasi-transverse wave received by mode 1 and mode 2, and the quasi-longitudinal wave signal received by mode 2. Obtain the two amplitude spectra and two phase spectra of the quasi-transverse wave and the one phase spectrum of the quasi-longitudinal wave by Fourier transform, and extract the amplitude of the quasi-transverse wave at a frequency of 1.2MHz. and Quasi-transverse wave phase and Quasi-longitudinal wave phase The quasi-transverse wave acoustic time difference variation and the quasi-longitudinal wave acoustic time difference variation are identified by equations (7), (8) and (9);

[0121] (5) Substitute the extracted acoustic time information into the following spatial strain-acoustic time constitutive relation, and in the calibration experiment, γ 12 =0,γ 13 =0,γ 23 =0, the spatial strain-acoustic time constitutive relation becomes

[0122]

[0123] Fit the calibration experimental data according to the above formula to determine the values ​​of a1, b1, c1, a2, b2, c2, a3, b3, c3, g1, h1, j1, g2, h2, j2, g3, h3, j3;

[0124] (6) The values ​​of the strain detection coefficients d1, e1, f1, k1, d2, e2, f2, k2, d3, e3, f3, and k3 related to shear strain are determined by the following formula:

[0125]

[0126] Among them, C 456 C 355 C 344 Let ρ0 be the third elastic constant of the material, ρ0 be the density of the steel, and μ be the Lamé constant of the material. and Representing the wave velocities of quasi-transverse and quasi-longitudinal waves propagating in steel under zero stress, taking...

[0127] (7) According to Hooke's Law, the strain detection coefficient matrix M is transformed into stress detection coefficient N by equation (17), and the values ​​of all stress detection coefficients are determined.

[0128] The third step is to determine the testing area and conduct a transverse wave transmission and reception test on the in-service steel plate components subjected to spatial stress to obtain the quasi-transverse wave acoustic time difference change and the quasi-longitudinal wave acoustic time difference change at the testing area location. The specific operation of this step is as follows:

[0129] (1) Transmit and receive ultrasonic waves at one transmitter and three receiver points in mode 1, and collect and store three sets of time domain signals;

[0130] (2) Adjust the transmitting sensor to transmit and receive ultrasonic waves in transceiver mode 2, and collect and store three sets of time domain signals again.

[0131] The fourth step involves performing spectral analysis on the six sets of time-domain signals collected, extracting the quasi-transverse wave acoustic time difference variation and the quasi-longitudinal wave acoustic time difference variation at a frequency of 1.2MHz along the three propagation paths, and substituting these values ​​into the spatial stress-acoustic time constitutive relation of the replicated specimen to solve for the spatial stress information of the in-service steel component. The specific operations for this step are as follows:

[0132] (1) Extract the time-domain signals of the quasi-transverse wave received by mode 1 and mode 2, and the quasi-longitudinal wave received by mode 2. Obtain the two amplitude spectra and two phase spectra of the quasi-transverse wave, and the one phase spectrum of the quasi-longitudinal wave by Fourier transform.

[0133] (2) Extract the quasi-transverse wave amplitude at a frequency of 1.2MHz. and Quasi-transverse wave phase and Quasi-longitudinal wave phase The quasi-transverse wave acoustic time difference variation and the quasi-longitudinal wave acoustic time difference variation are identified by equations (7), (8) and (9);

[0134] (3) Substitute the extracted quasi-transverse wave acoustic time difference and quasi-longitudinal wave acoustic time difference into the spatial stress-acoustic time constitutive relation (16) to obtain the spatial stress information of the in-service steel components.

[0135] Example 1

[0136] This invention selects a commonly used Q235b steel plate specimen with a thickness of 14mm and a length and width of 240mm and 140mm, respectively. Testing is performed according to the testing steps described in Example 1.

[0137] The first step is to determine the positioning points for the one-launch-three-receiver system within the test specimen, such as... Figure 7As shown, unidirectional pressure was applied to the specimen along the width direction starting from zero, with a stress gradient of 7.5 MPa. Each stress gradient was maintained for a sufficiently long time. In order to keep the steel plate in an elastic state, the upper limit of the applied stress was 165 MPa.

[0138] The second step involves transmitting and receiving ultrasonic signals in mode 1 at a single-transmitter, three-receiver calibration point within the duration of each stress gradient, and storing three sets of received signals, such as... Figure 8 As shown; the transmitting sensor is rotated by an angle of π / 2 to transmit and receive ultrasonic signals again in mode 2, and three sets of received signals are stored, as shown. Figure 9 As shown.

[0139] The third step is to rotate the steel plate by π / 2 angle after the first round of loading, change the direction of the specimen's compression, and apply unidirectional pressure to the specimen from zero along the length direction, with a stress gradient of 7.5 MPa. Each stress gradient is maintained for a sufficiently long time to ensure that the steel plate remains in an elastic state. The upper limit of the loaded stress is 165 MPa.

[0140] The fourth step involves transmitting and receiving ultrasonic signals in mode 1 at the one-transmitter-three-receiver calibration point during the duration of each stress gradient, followed by transmitting and receiving ultrasonic signals again in mode 2.

[0141] The fifth step involves extracting the target band from all acquired time-domain signals and performing a Fourier transform. In this invention, the quasi-transverse wave signal from Method 1 and the quasi-longitudinal and quasi-transverse wave signals from Method 2 are extracted, such as... Figure 8 and Figure 9 As shown; after performing a Fourier transform, the quasi-transverse wave's amplitude spectrum and phase spectrum are obtained, as shown in the figures below. Figure 10 and Figure 11 As shown, and the first phase spectrum of the quasi-longitudinal wave, as... Figure 12 As shown; the quasi-transverse wave amplitude at a frequency of 1.2MHz is extracted from it. and Quasi-transverse wave phase and Quasi-longitudinal wave phase The quasi-transverse wave acoustic time difference variation and the quasi-longitudinal wave acoustic time difference variation are identified by equations (7), (8) and (9). The obtained quasi-transverse wave acoustic time difference variation and longitudinal wave acoustic time difference variation are substituted into the theoretical formula (16), and all stress detection coefficient values ​​are determined by equations (18) and (19), as shown in Tables 1 and 2.

[0142] Step 6: Establish a non-uniform spatial stress field, such as Figure 13 As shown. Determine the detection areas Z1, Z2, Z3, and Z4, as follows. Figure 14As shown, an ultrasonic experiment was conducted in the detection area. An ultrasonic transverse wave was incident in mode 1, and three sets of time-domain signals were acquired and stored. The transmitting sensor was then rotated, and the wave was incident again in mode 2, acquiring and storing three sets of time-domain signals.

[0143] Step 7: Extract the quasi-transverse and quasi-longitudinal wave signals, and use Fourier transform to convert the time-domain signals into frequency-domain signals. Extract the amplitude of the quasi-transverse wave at a frequency of 1.2MHz. and Quasi-transverse wave phase and Quasi-longitudinal wave phase The quasi-transverse wave acoustic time difference variation and the quasi-longitudinal wave acoustic time difference variation are identified by equations (7), (8) and (9).

[0144] Step 8, identify (Δt) qS 1. (Δt) qS )2、(Δt qS )3 and (Δt qP 1. (Δt) qP )2、(Δt qP Substituting into the theoretical formula (16), the spatial stress information of the steel component to be tested is obtained. To verify the accuracy of this method, the present invention uses the finite element calculation results verified by the strain gauge method as a comparison, and the comparison results are shown in Table 3.

[0145] Table 1. Spatial strain detection coefficient values ​​for Q235b steel plates (f = 1.2MHz)

[0146]

[0147] Table 2. Spatial stress detection coefficient values ​​for Q235b steel plates (f = 1.2MHz)

[0148]

[0149] Table 3. Results and Comparison of Spatial Stress Tests for Q235b Steel Plates

[0150]

[0151] Example 2

[0152] This invention selects a 14mm thick Q345b steel plate as the experimental object, with a length and width of 240mm and 140mm respectively. Calibration and testing experiments were conducted according to the testing steps described in Example 1, and the obtained spatial stress detection coefficient values ​​are shown in Tables 4 and 5. Similarly, for the four testing points Z1, Z2, Z3, and Z4, finite element calculation results were used for comparison, and the comparison results are shown in Table 6.

[0153] Table 4. Spatial strain detection coefficient values ​​for Q345b steel plates (f = 1.2MHz)

[0154]

[0155] Table 5. Spatial stress detection coefficient values ​​for Q345b steel plates (f = 1.2MHz)

[0156]

[0157] Table 6. Results and Comparison of Spatial Stress Tests for Q345b Steel Plates

[0158]

[0159] As can be seen from the embodiments, the spatial stress detection method for steel components based on a transverse wave transmitter and receiver according to the present invention can achieve non-destructive testing of the internal spatial stress of in-service steel components of different materials and thicknesses. The testing instrument is easy to operate, has low testing cost, and is easy to implement; at the same time, it has high sensitivity and is easy to acquire data. It can be used for the detection of internal spatial stress of steel components under construction and already built, as well as for the detection of internal spatial stress of other metal plate components.

[0160] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for detecting spatial stress of a steel member based on one transmission and three receptions of a shear wave, characterized in that: The method comprises the following steps: S1, obtaining a replica specimen of a steel structure in service to be detected; S2, performing a unidirectional loading experiment and a transverse wave one-transmitting-three-receiving experiment on the replica specimen to determine a spatial stress detection coefficient matrix and obtain a spatial stress detection formula; S3, determining a detection area, performing a transverse wave one-transmitting-three-receiving spatial stress detection experiment on the steel structure in service in the detection area, and obtaining ultrasonic time domain signals at three receiving positions; S4, performing frequency spectrum analysis on the captured time domain signals, extracting a quasi-transverse wave sound time difference variation and a quasi-longitudinal wave sound time variation, and substituting the spatial stress detection formula of the replica specimen to obtain spatial stress information of the steel structure; The spatial stress information detection formula is as follows: where σ 11 , σ 22 , σ 33 , τ 12 , τ 13 , τ 23 are six spatial stress components, σ 11 , σ 22 , σ 33 are normal stresses in the length, height and thickness directions of the steel plate member, τ 12 is a shear stress in the plate, τ 13 and τ 23 are two out-of-plane shear stresses; N is a stress detection coefficient matrix, containing 36 stress detection coefficients o1-z3 related to the material and thickness of the member, and the frequency and propagation path of the ultrasonic wave; (Δt qS ) i is the change in the sound time difference of two quasi-transverse waves propagating in the member, (Δt qP ) i is the change in the sound time of one quasi-longitudinal wave, and the subscript i=1, 2, 3 represents the three receiving sensor positions. The change here refers to the change in the quasi-transverse wave sound time difference and the quasi-longitudinal wave sound time relative to the quasi-transverse wave sound time difference and the quasi-longitudinal wave sound time under a zero stress state, under a spatial stress state, and is expressed as follows: where t qS1 , t qS2 , and t qSP denote the propagation times of two quasi-S waves qS1 and qS2 and one quasi-P wave qP in the spatial stress state, respectively, and the superscript 0 denotes the corresponding times in the zero stress state. The quasi-transverse wave sound time difference change amount (Δt qS ) i , quasi-longitudinal wave sound time change amount (Δt qP ) i Substitute the spatial stress information detection formula, through multiple linear fitting and parameter calculation, the stress detection coefficient matrix N can be determined.

2. The method according to claim 1, wherein the replica specimen has the same thickness, material and strength as the steel structure in service and is reduced in size in proportion.

3. The method according to claim 1, wherein the step S2 comprises the following sub-steps: S21, building a steel structure spatial stress information detection hardware system; S22, applying unidirectional compression stress to the replica specimen step by step along the height direction, taking 7.5 MPa as a stress gradient, and keeping each gradient stress for a period of time for performing an ultrasonic experiment; S23, applying unidirectional compression stress to the replica specimen step by step along the length direction again, taking 7.5 MPa as a stress gradient, and keeping each gradient stress for a period of time for performing an ultrasonic experiment; S24, transmitting and receiving ultrasonic transverse waves at selected calibration positions during the keeping time of each stress gradient, collecting and storing time domain signals at three receiving positions under the stress state; S25, performing frequency spectrum analysis on the collected time domain signals, intercepting a quasi-transverse wave band, extracting a quasi-transverse wave sound time difference variation of 1.2 MHz frequency by using an amplitude spectrum and a phase spectrum of the quasi-transverse wave, intercepting a quasi-longitudinal wave band, and extracting a quasi-longitudinal wave sound time variation of 1.2 MHz frequency by using a phase spectrum of the quasi-longitudinal wave; S26, substituting the obtained quasi-transverse wave sound time difference variation and quasi-longitudinal wave sound time variation into the spatial stress information detection formula to determine the spatial stress detection coefficient matrix N through data fitting and parameter calculation.

4. The method according to claim 3, wherein the steel structure spatial stress information detection hardware system comprises an ultrasonic signal transmitter and receiver, a one-transmitting-three-receiving transverse wave sensor group, a digital oscilloscope, and a steel structure stress loading and controller. The one-transmitting-three-receiving transverse wave sensor group comprises four identical ultrasonic transverse wave sensors with a diameter of 9 mm, a center frequency of 5 MHz, and a main frequency range of 0-10 MHz, and the incident transverse wave is a multi-frequency coupled simple harmonic pulse wave. The stress loading and controller is an electro-hydraulic servo universal testing machine with a maximum pressure of 1000 KN.

5. The method according to claim 3, wherein when the unidirectional compression stress is applied to the replica specimen step by step, the maximum stress does not exceed the yield stress of the specimen material, so that the specimen is always in an elastic state.

6. The method according to claim 3, wherein ​ ​ ​ ​ Transmit and receive ultrasonic shear wave at selected calibration positions, place the transmitting sensor and the receiving sensor vertically, in parallel transmitting and receiving mode, transmit shear wave pulse, collect and store three sets of received time domain signals; Rotate the transmitting sensor by π / 2 angle, place it horizontally, at this time the transmitting sensor and the receiving sensor are in perpendicular transmitting and receiving mode, transmit shear wave pulse, collect and store three sets of received time domain signals.

7. The method of claim 6, wherein, The amplitude spectrum function of quasi-shear wave received by mode 1 is: The amplitude spectrum function of quasi-shear wave received by mode 2 is: The phase spectrum function of quasi-shear wave received by mode 1 is: The phase spectrum function of quasi-shear wave received by mode 2 is: The phase spectrum function of quasi-longitudinal wave received by mode 2 is: where f is the ultrasonic frequency, L i represents the propagation distance of the ultrasonic wave, φ i represents the polarization angle of the quasi-transverse wave, i = 1, 2, 3, and the superscripts / / and represent the transmission-reception modes 1 and 2, respectively; L r and φ r respectively represent the amplitude and phase of the received signal, which can be obtained by Fourier transform of the time-domain signal; Extract the acoustic travel time difference and the polarization angle of quasi-shear wave using the amplitude spectrum and the phase spectrum of quasi-shear wave received by mode 1 and mode 2, which are: Extract the acoustic travel time difference of quasi-longitudinal wave using the phase spectrum of quasi-longitudinal wave received by mode 2, which is: Wherein, T0 is a constant term, and in the above formula, f = 1.2 MHz.

8. The method of claim 1, wherein, The step S3 comprises the following sub-steps: S31, select a three-transmitting-one-receiving detection position in the region to be detected, transmit ultrasonic shear wave in mode 1, collect and store three sets of received ultrasonic time domain signals; S32, rotate the transmitting sensor, transmit shear wave in mode 2 again, collect and store three sets of received ultrasonic time domain signals.

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