Normal stress and shear stress detection device and method based on acoustic elastic effect
阅读说明：本技术 一种基于声弹性效应的法向应力与剪切应力检测装置及检测方法 (Normal stress and shear stress detection device and method based on acoustic elastic effect ) 是由 李佳鑫 史维佳 赵勃 谭久彬 于 2021-09-02 设计创作，主要内容包括：本发明提出一种基于声弹性效应的法向应力与剪切应力检测装置及检测方法：超声应力测量系统包括：超声信号发射装置,示波器,超声换能器探头和标准件；超声换能器探头的一端分别超声信号发射装置和示波器的CH1端口相连接,超声换能器探头的另一端与示波器的CH2端口相连接,超声换能器探头放置在标准件上在测得需要做应力测量结构件的声弹性常数后,通过对信号进行离散时域信号的Hilbert变换,进行波包提取后计算信号频域相位,从而得到该信号由应力引起的相移数值,再代入声弹性方程得到所测表面较为精确的的应力值。(The invention provides a normal stress and shear stress detection device and method based on an acoustic elastic effect, which comprises the following steps: an ultrasonic stress measurement system comprising: the ultrasonic signal transmitting device comprises an ultrasonic signal transmitting device, an oscilloscope, an ultrasonic transducer probe and a standard part; one end of an ultrasonic transducer probe is respectively connected with a CH1 port of an oscilloscope, the other end of the ultrasonic transducer probe is connected with a CH2 port of the oscilloscope, the ultrasonic transducer probe is placed on a standard component, after an acoustic elastic constant of a structural component needing stress measurement is measured, Hilbert transformation of a discrete time domain signal is carried out on the signal, a signal frequency domain phase is calculated after wave packet extraction is carried out, and therefore a phase shift value caused by stress of the signal is obtained, and the phase shift value is substituted into an acoustic elastic equation to obtain a stress value with a more accurate measured surface.)
1. The utility model provides a normal stress and shear stress detection device based on acoustoelastic effect which characterized in that:
preparing a zero-stress standard part (4) which is made of the same material as the stress structural part to be tested, setting a rectangular coordinate system by taking the surface center of the standard part (4) as an original point, wherein the short side is an x axis, and the long side is a y axis; calibrating the position S of the ultrasonic emission probe on the surface of the standard component (4)1And the placement position S of the ultrasonic receiving probe2And placing the probe; s1,S2There are three placement modes;
one end of the ultrasonic transducer probe (3) is respectively connected with the CH1 ports of the ultrasonic signal emitting device (1) and the oscilloscope (2), the other end of the ultrasonic transducer probe (3) is connected with the CH2 port of the oscilloscope (2), and the ultrasonic transducer probe (3) is arranged on the standard component (4).
2. The apparatus of claim 1, wherein:
S1,S2the three placing modes are respectively as follows:
S1,S2on the y-axis and symmetrical about the x-axis, S1,S2Lying on the x-axis and being symmetrical about the y-axis, S1,S2Symmetrical about the origin and S1The included angle between the connecting line of the origin and the positive half shaft of the y axis is theta;
three ways S1And S2All the distances of (A) are L.
3. A normal stress and shear stress detection method based on an acoustic elastic effect is characterized in that:
the method comprises the following steps: the ultrasonic signal transmitting device (1) excites the ultrasonic transmitting probe to transmit critical refraction longitudinal waves, the critical refraction longitudinal waves are received by the ultrasonic receiving probe through the surface of the standard part (4), and transmitting signals and receiving signals of the probe are obtained through the dual-channel oscilloscope (2); recording the time intervals of transmitting signals and receiving signals of three probe placement modes under the condition of zero stress, wherein the time intervals are t1,t2,t3Taking the mean value and defining as zero stress sound, and then obtaining the zero stress sound velocity v from the zero stress sound0；
Step two: hilbert transformation of discrete time domain signal is carried out on the signal, and frequency domain phase of the signal is calculated
Three groups of discrete time domain signals corresponding to the three probe placement modes stored by the dual-channel oscilloscope (2) are extracted, the waveform of a receiving part is intercepted, and the direct current quantity of the signals is eliminated; carrying out Hilbert transformation on discrete signals of the signals for eliminating the direct current quantity to obtain a sampling point-amplitude diagram and a sampling point-phase diagram of the Hilbert transformation;
selecting the sample point with the maximum amplitude value, recording the phase phi of the sample point, and respectively obtaining initial phase information phi by the three groups of data1，φ2，φ3；
Step three: obtaining a signal frequency domain phase shift value caused by stress;
clamping the standard component by using a stretching instrument, setting the stretching force loaded on the standard component (4) by the stretching instrument to be F, setting the section area of the middle section of the standard component to be S, and setting the middle stress sigma vertical to the section direction to be:
measuring the time intervals of ultrasonic emission and reception generated by the three probe placement modes of the standard component (4) in a clamping state respectively, and storing ultrasonic emission and reception signal waveform data on the oscilloscope;
extracting three groups of discrete time domain signals stored by the oscilloscope, intercepting the waveform of a receiving part, eliminating the direct current quantity of the signals, carrying out Hilbert transformation on the signals, selecting a sampling point with the maximum amplitude value, and recording the phase phi' of the sampling point; three groups of data can obtain initial phase information phi'1，φ′2，φ′3Is respectively equal to phi1，φ2，φ3Calculating the difference to obtain the phase shift of signal frequency domain delta phi (f)1,Δφ(f)2,Δφ(f)3；
The phase of the conversion of the ratio of the acoustic time difference in the time domain to the zero stress acoustic time to the frequency domain is:
where f is the frequency of the computation point, Δ φ (f) is the signal phase shift at the frequency of the computation point, v0Is zero stress sound velocity, and L is the placing position S of the probe1,S2The distance of (d);
step four: obtaining the stress value of the measured surface according to the acoustic elastic equation;
the acoustoelastic equation is:
where Δ t is the acoustic time difference, t0At zero stress sound, K1,K2,K3Is the acoustic elastic constant, σ is the stress, σ11And σ22Stress in the x-axis direction and stress in the y-axis direction, respectively;
σ′11,σ′22,σ′12the calculation formula of (2) is as follows:
wherein the stress sigma11And σ22To a known quantity, Δ φ (f)1,Δφ(f)2,Δφ(f)3The acoustic elastic constant K can be obtained by substituting the formula (3), the formula (4) and the formula (5)1,K2,K3。
4. The method of claim 3, wherein:
when the normal stress and the shear stress at the corner of the piece to be measured are measured, the waveform data of ultrasonic wave transmission and reception are obtained according to the same method as the standard piece, and the normal stress and the shear stress of the position area to be measured can be obtained by substituting the acoustic elastic constant, the phase change numerical value and the zero stress sound velocity measured by the standard piece into an acoustic elastic equation.
Technical Field
The invention belongs to the technical field of ultrasonic stress detection, and particularly relates to a normal stress and shear stress detection device and method based on an acoustic elastic effect.
Background
The aerospace field, the nuclear industry field, the traffic industry field and the like have wide stress detection requirements, for example, stress detection of airplane wings, local stress detection of key devices in the nuclear industry and rail stress detection of railway traffic, and timely detection of local stress of structural members has important significance for evaluating the service life condition of equipment structures and avoiding huge loss or damage. Common stress detection methods include pinhole method, X-ray diffraction method, neutron diffraction method, electromagnetic ultrasonic method and ultrasonic stress detection method. The pinhole method is to drill holes on the surface of the structural member and detect strain of the pinholes to reflect the stress of the surface, and the method can damage the surface of the structural member. The method of X-ray detection and neutron diffraction belongs to a nondestructive detection method, the stress detection precision is high, but the equipment is huge and the manufacturing cost is high, so that the method is not suitable for detecting in-service structural parts. The electromagnetic ultrasonic method is used for realizing magnetostriction of a structural part through an electromagnetic effect, and the method is only suitable for ferromagnetic materials. The ultrasonic stress detection method based on the acoustic elastic effect is a convenient and feasible stress detection method. The internal stress of the material can influence the structure of the material lattice, and the speed of sound wave propagation can be influenced due to the change of the microstructure of the material when sound waves pass through, so that the time of sound wave propagation is influenced. By utilizing the property of the sound wave, the normal stress and the shear stress at the position of the material can be obtained by solving the acoustic elastic equation.
The ultrasonic stress detection is nondestructive and convenient and easy to detect, so that the ultrasonic stress detection is widely researched and applied in the field of stress detection. The middle Qingdao four-side rolling stock company provides an ultrasonic residual stress detection system and method, and an ultrasonic residual stress detection system and method. Publication No.: CN 112697328A. A complex mechanical motion device is designed to calculate the residual stress of the welded parts by measuring the change of the acoustic time difference. The method is based on the grain size of the known material, the signal attenuation degree, the acoustic elastic coefficient and other parameters, and the residual stress is measured by a special clamping device. The method has problems that: due to the particularity of the clamping device, the installation is inconvenient, and the application range is limited; the method mainly aims at detecting the welding residual stress of the vehicle, and for common steel aluminum materials, detailed acoustic elastic constants and grain sizes can be referred to, but for the fields of aircraft manufacturing and the like, most materials are composite materials with complex structures and various types, and no acoustic elastic parameters can be effectively referred to; the method is only used for measuring the residual stress in two orthogonal directions, and a shear stress measuring method is not provided, however, for some special structures such as structural members of I-shaped structures, the shear stress detection at the corner positions is more important.
The Shenzhen research institute of Shenzhen university in Harbin industry proposes a method for detecting the absolute stress distribution along the depth of a steel member based on an LCR wave method. Publication No.: CN 105203638A. The method mainly uses LCR waves to measure the depth distribution of stress, and has the limitation that the measured material structural part is a steel structural part, the depth stress distribution can be obtained only, and the shear stress on the surface of the structural part cannot be obtained.
The university of eastern China provides a nondestructive testing method for the residual stress on the surface of a sample, and the nondestructive testing method for the residual stress on the surface of the sample. Publication No.: CN 107328860A. The method designs an ultrasonic surface wave sound velocity measurement system which comprises an energy converter, a sample groove, an oscilloscope, a motor and the like, and local residual stress measurement is realized by measuring the wave velocity of the surface acoustic wave. The method is relatively complex in device, requires a specially designed sample groove, and cannot measure the shear stress of the surface.
A uniaxial tension experiment is designed according to a plane stress measurement theory and a plane stress measurement method based on a critical refraction longitudinal wave acoustic elastic effect, wave acoustic elastic constants which are propagated in a critical refraction longitudinal wave acoustic elastic equation in a direction parallel to a stress direction and in a direction perpendicular to the stress direction are calibrated aiming at a 7N01 aluminum alloy material, a stress measurement system is built by using a signal generator, an oscilloscope, a critical refraction longitudinal wave probe group, a digital oscilloscope and a computer, and the stress detection is completed by analyzing time-domain ultrasonic emission and receiving signals. The method only studies the plane stress of the metal, aluminum alloy. All signal analysis of the method is carried out on a time domain, a zero-crossing threshold point is used as a reference point for calculating sound, the sound time variation caused by material stress is nanosecond level, the measurement result is influenced by the measurement error, the calculation error and the like of an oscilloscope, and the stress value calculated by the time difference of the time domain signal has higher error.
Most of the existing ultrasonic stress detection methods are directed at steel materials, and the measuring device has a relatively complex structure, cannot be generally applied to structural members of most special materials, cannot obtain the material stress with unknown acoustic elastic coefficient, and cannot measure the shear stress of the material. Since the acoustic time variation due to stress is in the order of nanoseconds, the stress measurement results are subject to large errors only by measuring the acoustic time difference in the time domain. For example, the influence of stress of every 100MPa on ultrasonic sound is 10 ns-20 ns, and for a general oscilloscope, the sampling frequency is 1GHz, namely, one point is acquired every 1 ns. For the traditional method for calculating the stress by simply comparing the acoustic time difference of the stressed signal and the unstressed signal in the time domain, the calculation error of the acoustic time is at least 1 sampling period, namely 1ns, and the correspondingly caused stress calculation error is in the range of 5MPa to 10 MPa. Therefore, the ultrasonic stress measurement needs a measurement method which is generally applicable to most materials, can measure the surface shear force and effectively analyze signals so as to obtain a relatively accurate stress value.
Disclosure of Invention
Aiming at the defects of the ultrasonic stress detection method, the invention provides a normal stress and shear stress detection device and method based on the acoustic elastic effect, after the acoustic elastic constant of a stress measurement structural member is measured, through Hilbert transformation of a discrete time domain signal on the signal, after wave packet extraction, the frequency domain phase of the signal is calculated, so that the phase shift value of the signal caused by the stress is obtained, and then the phase shift value is substituted into an acoustic elastic equation to obtain the stress value with more accurate measured surface.
The invention is realized by the following method:
a normal stress and shear stress detection device based on acoustic elastic effect:
preparing a zero-stress standard part 4 which is made of the same material as the stress structural part to be tested, setting a rectangular coordinate system by taking the surface center of the standard part 4 as an original point, wherein the short edge is an x axis, and the long edge is a y axis; calibrating the position S of the ultrasonic emission probe on the surface of the standard component 41And the placement position S of the ultrasonic receiving probe2And placing the probe; s1,S2There are three placement modes;
one end of the ultrasonic transducer probe 3 is respectively connected with the CH1 ports of the ultrasonic signal emitting device 1 and the oscilloscope 2, the other end of the ultrasonic transducer probe 3 is connected with the CH2 port of the oscilloscope 2, and the ultrasonic transducer probe 3 is arranged on the standard component 4.
Further, S1,S2The three placing modes are respectively as follows:
S1,S2on the y-axis and symmetrical about the x-axis, S1,S2Lying on the x-axis and being symmetrical about the y-axis, S1,S2Symmetrical about the origin and S1The included angle between the connecting line of the origin and the positive half shaft of the y axis is theta;
three ways S1And S2All the distances of (A) are L.
A normal stress and shear stress detection method based on an acoustic elastic effect comprises the following steps:
the method comprises the following steps: the ultrasonic signal transmitting device 1 excites the ultrasonic transmitting probe to transmit critical refraction longitudinal waves, the critical refraction longitudinal waves are received by the ultrasonic receiving probe through the surface of the standard part 4, and transmitting signals and receiving signals of the probe are obtained through the dual-channel oscilloscope 2; recording the time intervals of transmitting signals and receiving signals of three probe placement modes under the condition of zero stress, wherein the time intervals are t1,t2,t3Taking the mean value and defining as zero stress sound, and then obtaining the zero stress sound velocity v from the zero stress sound0；
Step two:
three groups of discrete time domain signals corresponding to the three probe placement modes stored by the two-channel oscilloscope 2 are extracted, the waveform of a receiving part is intercepted, and the direct current quantity of the signals is eliminated; carrying out Hilbert transformation on discrete signals of the signals for eliminating the direct current quantity to obtain a sampling point-amplitude diagram and a sampling point-phase diagram of the Hilbert transformation;
selecting the sample point with the maximum amplitude value, recording the phase phi of the sample point, and respectively obtaining initial phase information phi by the three groups of data1，φ2，φ3；
With extensometer centre gripping standard, it is F to establish the tensile force of loading on the standard through the extensometer, and the cross sectional area of cross-section is S in the middle part of the standard, and then the perpendicular middle part stress sigma of cross-sectional direction is:
measuring three groups of ultrasonic wave transmitting and receiving waveform data of the standard component in a clamping state, and storing three groups of waveform data information of the oscilloscope;
measuring the time intervals of ultrasonic emission and reception generated by the three probe placement modes of the standard part 4 in a clamping state respectively, and storing ultrasonic emission and reception signal waveform data on the oscilloscope;
extracting three groups of discrete time domain signals stored by the oscilloscope, intercepting the waveform of a receiving part, eliminating the direct current quantity of the signals, carrying out Hilbert transformation on the signals, selecting a sampling point with the maximum amplitude value, and recording the phase phi' of the sampling point; three groups of data can obtain initial phase information phi1′，φ2′，φ3', each is equal to phi1，φ2，φ3Calculating the difference to obtain the phase shift of signal frequency domain delta phi (f)1,Δφ(f)2,Δφ(f)3；
The phase of the conversion of the ratio of the acoustic time difference in the time domain to the zero stress acoustic time to the frequency domain is:
where f is the frequency of the computation point, Δ φ (f) is the signal phase shift at the frequency of the computation point, v0Is zero stress sound velocity, and L is the placing position S of the probe1,S2The distance of (d);
step four: obtaining the stress value of the measured surface according to the acoustic elastic equation;
the acoustoelastic equation is:
where Δ t is the acoustic time difference, t0At zero stress sound, K1,K2,K3Is the acoustic elastic constant, σ is the stress, σ11And σ22Stress in the x-axis direction and stress in the y-axis direction, respectively;
σ′11,σ′22,σ′12the calculation formula of (2) is as follows:
wherein the stress sigma11And σ22To a known quantity, Δ φ (f)1,Δφ(f)2,Δφ(f)3The acoustic elastic constant K can be obtained by substituting the formula (3), the formula (4) and the formula (5)1,K2,K3。
Further, when measuring the normal stress and shear stress at the corner of the piece to be measured, the ultrasonic wave transmitting and receiving waveform data is obtained according to the same method as the standard piece, and the normal stress and shear stress of the measured position area can be obtained by substituting the acoustic elastic constant, the phase change numerical value and the zero stress sound velocity measured by the standard piece into the acoustic elastic equation.
The invention has the beneficial effects
(1) The invention can obtain the acoustic elastic constant of a certain material by the method, and the method can be generally suitable for measuring the stress of the material structural member after one measurement;
(2) the measuring method can complete measurement without a special mechanical device, and is relatively simple and convenient;
(3) the invention can measure the shear stress at any position;
(4) the invention converts the time domain ultrasonic signal information into the frequency domain through Hilbert transformation to obtain the envelope, and then calculates the stress by measuring the phase shift of the frequency domain signal. A time calculation reference can be more effectively defined by calculating the sampling points corresponding to the maximum value of the envelope, so that the calculation is more accurate, and meanwhile, the calculation error caused by insufficient sampling rate can be reduced by calculating the phase shift.
Drawings
FIG. 1 is a schematic drawing of a standard part according to the present invention;
FIG. 2 is a schematic diagram of the measurement of the acoustic elastic constant of the present invention;
FIG. 3 is a schematic diagram of an ultrasonic stress measurement system of the present invention; wherein, the ultrasonic signal emission and excitation device 1, the dual-channel oscilloscope 2, the ultrasonic transducer probe 3 and the standard component 4 are arranged in the ultrasonic signal emission and excitation device;
FIG. 4 is a schematic diagram illustrating normal stress and shear stress measurements of a test part according to the present invention;
FIG. 5 is a two-dimensional stress plane and ultrasonic measurement directional diagram;
FIG. 6 is a signal collected and a signal with DC offset removed;
FIG. 7 is a graph of the amplitude and phase of a signal after Hilbert transform at zero stress;
FIG. 8 is a graph of the magnitude and phase of a signal after Hilbert transform under stress.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
With reference to fig. 1 to 8;
normal stress and shear stress detection device based on acoustic elastic effect
Preparing a zero-stress standard part 4 which is made of the same material as the stress structural part to be tested, and setting a rectangular coordinate system by taking the surface center of the standard part 4 as an original point as shown in FIG. 2, wherein the short side is an x axis and the long side is a y axis; calibrating the position S of the ultrasonic emission probe on the surface of the standard component 41And the placement position S of the ultrasonic receiving probe2And placing the probe; s1,S2There are three placement modes;
as shown in fig. 3, one end of an ultrasonic transducer probe 3 is connected to CH1 ports of the ultrasonic signal emitting device 1 and the oscilloscope 2, the other end of the ultrasonic transducer probe 3 is connected to CH2 port of the oscilloscope 2, and the ultrasonic transducer probe 3 is placed on the standard component 4.
S1,S2The three placing modes are respectively as follows:
S1,S2on the y-axis and symmetrical about the x-axis, S1,S2Lying on the x-axis and being symmetrical about the y-axis, S1,S2Symmetrical about the origin and S1The included angle between the connecting line of the origin and the positive half shaft of the y axis is theta;
three ways S1And S2All the distances of (A) are L.
A normal stress and shear stress detection method based on an acoustic elastic effect comprises the steps of carrying out Hilbert transformation on a signal by measuring an acoustic elastic constant of a structural member needing stress measurement, carrying out wave packet extraction on the signal, calculating a signal frequency domain phase, obtaining a phase shift value of the signal caused by stress, and substituting the phase shift value into an acoustic elastic equation to obtain a stress value with a more accurate measured surface.
The method comprises the following steps: the ultrasonic signal transmitting device 1 excites the ultrasonic transmitting probe to transmit critical refraction longitudinal waves, the critical refraction longitudinal waves are received by the ultrasonic receiving probe through the surface of the standard part 4, and transmitting signals and receiving signals of the probe are obtained through the dual-channel oscilloscope 2; recording three probe placing modes under zero stress conditionThe time interval between the transmitted signal and the received signal is t1,t2,t3Taking the mean value and defining as zero stress sound, and then obtaining the zero stress sound velocity v from the zero stress sound0；
Step two:
three groups of discrete time domain signals corresponding to the three probe placement modes stored by the two-channel oscilloscope 2 are extracted, the waveform of a receiving part is intercepted, and the direct current quantity of the signals is eliminated; as shown in fig. 6.
Hilbert transformation of discrete signals is carried out on the signals with the direct current quantity eliminated, and a sampling point-amplitude diagram of the Hilbert transformation, namely an envelope diagram and a sampling point-phase diagram of the discrete signals, is obtained;
as shown in fig. 7, a sample point with the maximum amplitude is selected, and the phase phi of the sample point is recorded, so that the three sets of data respectively obtain initial phase information phi1，φ2，φ3；
Clamping the standard part by using a stretching instrument, setting the stretching force loaded on the standard part 4 by the stretching instrument to be F, setting the section area of the middle section of the standard part in figure 1 to be S, and setting the middle stress sigma vertical to the section direction according to the Saint-Venn principle to be:
and measuring the time interval of ultrasonic emission and reception generated by the standard part 4 according to the three probe placement modes shown in the figure 2 in the clamping state, and storing ultrasonic emission and reception signal waveform data on the oscilloscope.
When the two ends of the standard component are clamped by the stretching instrument to be stretched, the middle part of the standard component far away from the stress point is uniformly stressed and has the same magnitude as the tensile force given by the stretching instrument, and the stress value of the middle part of the standard component can be obtained according to the middle tensile force value and the cross-sectional area value.
Extracting three groups of discrete time domain signals stored by oscilloscopeThe waveform of the received part is cut and the dc component of the signal is removed and Hilbert transformed, and a signal similar to the envelope of fig. 7 is selected as shown in fig. 8. According to the time shift property of Hilbert transformation, the amplitude value of a signal after Hilbert transformation cannot be changed when the signal moves in a time domain, only the phase value of the signal after Hilbert transformation is changed, a sampling point with the maximum amplitude value is still selected, and the phase phi' of the sampling point is recorded; three groups of data can obtain initial phase information phi1′，φ2′，φ3', each is equal to phi1，φ2，φ3Calculating the difference to obtain the phase shift of signal frequency domain delta phi (f)1,Δφ(f)2,Δφ(f)3；
The phase of the conversion of the ratio of the acoustic time difference in the time domain to the zero stress acoustic time to the frequency domain is:
where f is the frequency of the computation point, Δ φ (f) is the signal phase shift at the frequency of the computation point, v0Is zero stress sound velocity, and L is the placing position S of the probe1,S2The distance of (d);
step four: obtaining the stress value of the measured surface according to the acoustic elastic equation;
the acoustoelastic equation is:
where Δ t is the acoustic time difference, t0At zero stress sound, K1,K2,K3Is the acoustic elastic constant, σ is the stress, σ11And σ22Stress in the x-axis direction and stress in the y-axis direction, respectively;
σ′11,σ′22,σ′12the calculation formula of (2) is as follows:
wherein the stress sigma11And σ22To a known quantity, Δ φ (f)1,Δφ(f)2,Δφ(f)3The acoustic elastic constant K can be obtained by substituting the formula (3), the formula (4) and the formula (5)1,K2,K3。
When the normal stress and the shear stress at the corner of the piece to be measured are measured, the waveform data of ultrasonic wave transmission and reception are obtained according to the same method as the standard piece, and the normal stress and the shear stress of the position area to be measured can be obtained by substituting the acoustic elastic constant, the phase change numerical value and the zero stress sound velocity measured by the standard piece into an acoustic elastic equation.
For a structural member having a shape like that of fig. 4, normal stress and shear stress at the corner thereof were measured. According to the mode shown in fig. 4, after a couplant is coated on the surface of the structural component, the ultrasonic probe is put, the ultrasonic signal transmitting device excites the ultrasonic transmitting probe to transmit critical refraction longitudinal waves, and the ultrasonic waves are received by the ultrasonic receiving probe through the surface of the structural component. The transmitting signal and the receiving signal of the probe can be obtained through the dual-channel oscilloscope, and three groups of waveform data are stored.
Three groups of discrete time domain signals stored in the oscilloscope are extracted, and the signal phase shift delta phi (f) can be obtained by processing the data according to the data processing method in the above calculation of the acoustic elastic constant1,Δφ(f)2,Δφ(f)3. The acoustic elastic constant K can be obtained by the above calculation method1,K2,K3Will delta phi (f)1,Δφ(f)2,Δφ(f)3,K1,K2,K3Substituting equations (3), (4) and (5) to obtain the normal stress sigma at the position where the structural member is located11,σ22And shear stress sigma12。
The normal stress and shear stress detection device and method based on the acoustic elastic effect provided by the invention are introduced in detail, the principle and the implementation mode of the invention are explained, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
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