Metal material performance detection method, sensor and system based on longitudinal wave resonance

Abstract

The invention discloses a metal material performance detection method based on longitudinal wave resonance, metal material performance detection is carried out based on a laser and a metal material performance detection sensor, and the metal material performance detection sensor comprises an electromagnetic ultrasonic transducer EMAT and a magnetism gathering ring; the method comprises the steps that EMAT and a magnetism gathering ring are arranged on the two sides of a metal material sample respectively; laser emitted by the laser device penetrates through the magnetism gathering ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, the ultrasonic resonance signal is finally received by the EMAT, and the performance of the metal material sample is detected based on the ultrasonic resonance signal received by the EMAT. The detection effect of the performance of the metal material can be improved.

Description

Technical Field

[0001] The present application relates to the field of metal material performance detection, and specifically to a metal material performance detection method, sensor and system based on longitudinal wave resonance. Background Art

[0002] Aerospace metal materials are often affected by high temperature environments and complex mechanical loads. Deformation and crack propagation will occur before high temperature creep and fatigue failure. Especially under the erosion and corrosion of high temperature and high pressure gas, metal parts will also become locally thinner, resulting in a significant decrease in structural performance, seriously affecting the reliability of hot end components working in high temperature environments. The actual application environment of advanced materials and components determines the development direction of material properties and testing technology. At present, there are still gaps in the testing technology and testing standards for mechanical properties of materials under extreme environments at home and abroad, and the construction of the testing system is still not perfect. Therefore, the development of a new acoustic detection system for extreme environments has great engineering application value.

[0003] Ultrasonic transducers that can be used in high-temperature detection must meet the basic conditions of high temperature resistance or non-contact. At present, contact piezoelectric ultrasonic detection has been successfully applied to a variety of high-temperature detection occasions, but piezoelectric ultrasound cannot be separated from the sample being tested, which will make it difficult to move the probe during detection, and there is a problem of ultrasonic energy loss caused by loose fitting. It is difficult to apply to special-shaped components or curved complex interfaces, and it is not suitable for detection in high-temperature vibration environments; non-contact air-coupled ultrasound does not require coupling agents and has great high-temperature application prospects, but air-coupled ultrasound has the problem of low amplitude and poor signal-to-noise ratio of the received ultrasonic signal due to the serious mismatch of acoustic impedance between the air medium and the ultrasonic transducer material, and the detection objects of air-coupled ultrasound are usually limited to low-density porous materials. The limited frequency range, low signal-to-noise ratio and lack of pulse echo capability all hinder the detection of metal materials by air-coupled ultrasound at high temperatures; laser ultrasonic technology, as a completely non-contact non-destructive testing technology, can perform non-destructive testing and monitoring of complex structural parts in high temperature, high pressure, radiation and other environments. Laser ultrasonic technology combines the advantages of optical and ultrasonic testing, with the characteristics of non-destructive, non-contact, wide bandwidth, high precision, zero inertia and high efficiency. It can obtain information such as mechanical properties parameters and damage defects of materials and components, without considering the poor heat resistance of coupling agents and acoustic energy attenuation in contact ultrasonic testing methods. It has high-temperature application prospects. However, laser ultrasonic testing technology has high requirements on the surface roughness of the sample, which seriously affects the excitation and reception of ultrasonic signals in high-temperature environments; non-contact electromagnetic ultrasonic testing technology is widely used in high-temperature testing due to its advantages such as simple equipment, low cost, diverse excitation waveforms, and low requirements on sample surface morphology. At present, the main problems of electromagnetic ultrasonic testing are low transducer efficiency and low signal-to-noise ratio of detection signals. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a method, a sensor and a system for detecting the properties of metal materials based on longitudinal wave resonance, which can improve the detection effect.

[0005] In the first aspect, the present application provides a method for detecting the properties of metal materials based on longitudinal wave resonance, which performs metal material performance detection based on a laser and a metal material performance detection sensor, wherein the metal material performance detection sensor includes an electromagnetic ultrasonic transducer EMAT (English: ElectromagneticAcoustic Transducer) and a magnetic focusing ring; the method includes: placing the EMAT and the magnetic focusing ring on both sides of the metal material sample, respectively; the laser emitted by the laser passes through the magnetic focusing ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, which is finally received by the EMAT, and the performance of the metal material sample is detected based on the ultrasonic resonance signal received by the EMAT.

[0006] In a possible implementation, the liquid-solid mixed material covering the surface of the metal material sample is silver silicone grease.

[0007] In a possible implementation, the detecting the performance of the metal material sample based on the ultrasonic resonance signal received by the EMAT includes:

[0008] Performing power spectral density (PSD) analysis on the ultrasonic resonance signal received based on EMAT to obtain a power spectral density function of the ultrasonic resonance signal;

[0009] Determine each resonant frequency point of the ultrasonic resonant signal according to the power spectrum density function;

[0010] Based on each resonant frequency point, the thickness of the metal material sample to be tested is calculated according to the following formula:

[0011]

[0012] Among them, f p is the pth resonant frequency point, f q is the qth resonant frequency point, p>q≥1, d is the thickness of the metal material sample to be tested, and c is the ultrasonic sound velocity.

[0013] In a second aspect, the present application provides a metal material performance detection sensor, which is used in the above-mentioned metal material performance detection method;

[0014] The metal material performance detection sensor includes an EMAT and a magnetic focusing ring;

[0015] The EMAT comprises a base permanent magnet and a coil;

[0016] The basic permanent magnet includes two square permanent magnets, a yoke and a coil; the yoke is arranged above the two square permanent magnets, and the coil is arranged in the middle of the lower part of the two square permanent magnets; the two square permanent magnets are arranged symmetrically and have opposite polarities, the upper half of the square permanent magnet on the left is magnetized to the S pole, and the lower half is magnetized to the N pole, and the upper half of the square permanent magnet on the right is magnetized to the N pole, and the lower half is magnetized to the S pole;

[0017] Correspondingly, the magnetic focusing ring is a radially magnetized annular permanent magnet, the left half of the magnetic focusing ring is magnetized to the N pole, and the right half is magnetized to the S pole.

[0018] The present application also provides a metal material performance detection sensor, which is used in the above-mentioned metal material performance detection method;

[0019] The metal material performance detection sensor includes an EMAT and a magnetic focusing ring;

[0020] The EMAT comprises a base permanent magnet and a coil;

[0021] The basic permanent magnet includes a first permanent magnet, a second permanent magnet and a soft magnetic concentrator;

[0022] The first permanent magnet and the soft magnetic concentrator are cylindrical; the second permanent magnet is annular column;

[0023] The first permanent magnet, the second permanent magnet and the soft magnetic concentrator are coaxially arranged;

[0024] The first permanent magnet is placed on the soft magnetic concentrator;

[0025] The second permanent magnet and the soft magnetic concentrator are of equal height, and their bottom surfaces are on the same plane; the second permanent magnet is sleeved outside the soft magnetic concentrator;

[0026] The diameter of the soft magnetic concentrator is equal to the inner diameter of the second permanent magnet and smaller than the diameter of the first permanent magnet;

[0027] The second permanent magnet is magnetized in radial direction and is divided into an inner part and an outer part; the outer diameter of the inner part is larger than the diameter of the first permanent magnet; the inner diameter of the outer part is equal to the outer diameter of the inner part;

[0028] The first permanent magnet and the magnetic focusing ring correspondingly adopt a first magnetization structure:

[0029] The first permanent magnet is magnetized along the axial direction and is divided into two parts, the upper part is magnetized to an N pole, and the lower part is magnetized to an S pole;

[0030] The inner part of the second permanent magnet is magnetized to an S pole, and the outer part of the second permanent magnet is magnetized to an N pole;

[0031] Correspondingly, the magnetic focusing ring is an axially magnetized annular permanent magnet, the upper half of the magnetic focusing ring is magnetized to the N pole, and the lower half is magnetized to the S pole.

[0032] Alternatively, the first permanent magnet and the magnetic focusing ring correspondingly adopt a second magnetization structure:

[0033] The first permanent magnet is magnetized along the axial direction and is divided into an upper and a lower part, wherein the upper part is magnetized to an S pole and the lower part is magnetized to an N pole;

[0034] The inner part of the second permanent magnet is magnetized to an N pole, and the outer part of the second permanent magnet is magnetized to an S pole;

[0035] Correspondingly, the magnetic focusing ring is an axially magnetized annular permanent magnet, the upper half of the magnetic focusing ring is magnetized to the S pole, and the lower half is magnetized to the N pole.

[0036] In a possible implementation manner, the coil is a linear coil.

[0037] In a possible implementation manner, the coil is a spiral coil.

[0038] In a possible implementation, the basic permanent magnet and coil of the EMAT are assembled in a housing with an opening at the front end; the coil is a ceramic silver coil resistant to high temperatures of 800°C; a gel resistant to high temperatures of 1000°C is filled between the housing and the basic permanent magnet and coil; a heat-insulating film is provided between the coil and the front end of the housing;

[0039] The basic permanent magnet and the magnetic focusing ring are both made of SmCo permanent magnets that can withstand a high temperature of 350°C.

[0040] In a third aspect, the present application provides a metal material property detection system based on longitudinal wave resonance, comprising a laser and a metal material property detection sensor as described in any one of claims 5 to 7;

[0041] The laser is used as the excitation part, and the metal material performance detection sensor is used as the receiving part;

[0042] When in use, the laser emitted by the laser passes through the magnetic focusing ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, which is finally received by the EMAT; the metal material performance test results are calculated based on the ultrasonic resonance signal collected by the EMAT.

[0043] In a possible implementation, the system further includes a multi-joint rotating shaft mechanical light guide arm matched with the laser, which is used to realize three-dimensional light path deflection, so that the laser light emitted by the laser passes through the magnetic focusing ring along the axial direction of the magnetic focusing ring and is emitted to the metal material sample;

[0044] The system also includes two programmable robotic arms, which are used to drive the EMAT and the magnetic focusing ring to move respectively, so as to realize the function of path scanning of the metal material sample.

[0045] In a possible implementation, the system further includes a heating belt for heating the metal material sample, which can achieve a high-temperature heating function of more than 1000°C.

[0046] In a possible implementation, the system further includes a three-dimensional vibration platform for applying vibration to the metal material sample.

[0047] The metal material sample is heated by a high-temperature heating belt and matched with a three-dimensional vibration platform. The metal material sample is wrapped with thermal insulation cotton, which can simulate the complex working environment of high temperature vibration.

[0048] In a possible implementation, the system further includes an impedance matcher, a preamplifier, a data acquisition card and a computer connected in sequence; wherein the impedance matching module is used to adjust the matching capacitance and inductance parameters of the EMAT coil, thereby increasing the amplitude and signal-to-noise ratio of the received ultrasonic resonance signal while increasing the bandwidth of the ultrasonic resonance signal; the preamplifier is used to process the ultrasonic resonance signal, and the data acquisition card transmits the amplified ultrasonic resonance signal to the computer, and the computer is used to perform PSD analysis on the received ultrasonic resonance signal to obtain the power spectrum density function of the ultrasonic resonance signal, that is, the resonance spectrum signal.

[0049] Beneficial effects:

[0050] The present application proposes a laser-electromagnetic ultrasonic longitudinal wave resonance method based on the material surface constraint mechanism to perform high-temperature material performance detection and safety assessment of hot end components. A detection method combining laser ultrasonic excitation and electromagnetic ultrasonic reception is used to achieve true non-contact detection. At the same time, a resonance method using frequency domain thickness measurement technology is used for thickness measurement, which can greatly increase the amplitude of the detection signal and is beneficial to the surface constraint mechanism. Silver silicone grease is used to further increase the amplitude of the longitudinal wave signal, overcoming the problem of low transducer efficiency of electromagnetic ultrasonic detection.

[0051] The present application proposes two new basic permanent magnet structures, and utilizes a magnetic focusing ring for the EMAT configuration form of magnetic focusing, which can greatly increase the bias magnetic field required for electromagnetic ultrasonic receiving signals without hindering the normal passage of the laser light path, significantly improving the conversion efficiency of the electromagnetic ultrasonic transducer, and after combining with the resonance method for thickness measurement, the signal-to-noise ratio of the detection signal is significantly improved, thereby enabling large-lift-off corrosion thinning detection.

[0052] This application proposes to introduce a signal processing method of PSD analysis to improve the signal-to-noise ratio of the laser-electromagnetic ultrasonic resonance detection signal, which can be compatible with the resonance thickness detection under the frequency domain signal, and can further improve the signal-to-noise ratio of the received signal and the variable lift-off detection capability.

[0053] This application proposes the use of a high-temperature resistant ceramic silver coil with a 350°C resistant SmCo permanent magnet, and the use of a high-temperature resistant gel for infusion. The bottom of the sensor is further isolated by a high-temperature insulation film, which not only plays an insulating role, but also has the characteristics of wear resistance, high temperature resistance, and corrosion resistance, and can achieve high-temperature resistance and continuous online monitoring above 800°C.

[0054] The present application proposes a performance evaluation and detection system for aerospace hot end components in a high-temperature vibration environment, which can simulate the high-temperature vibration environment of aircraft engine turbine blades and tail nozzles, realize online acoustic detection of alloy material damage, and provide experimental data to guide the development and preparation of high-temperature alloy materials with high service performance in ultra-high temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is an ultrasonic excitation diagram under the thermoelastic mechanism in the embodiment of the present application;

[0056] Figure 2 This is a diagram of the surface constraint mechanism based on the thermoelastic mechanism in the embodiment of the present application;

[0057] Figure 3 This is a schematic diagram of a basic permanent magnet combined with a magnetic focusing ring structure in an embodiment of the present application; wherein, Figure 3 (a) is a longitudinal section view. Figure 3 (b) is a stereogram;

[0058] Figure 4 This is another basic permanent magnet structure schematic diagram in the embodiment of the present application; wherein, Figure 3 (a) is a longitudinal section view. Figure 3 (b) is a top view;

[0059] Figure 5 This is a schematic diagram of the EMAT structure in an embodiment of the present application.

[0060] Figure 6 A schematic diagram of the structure of a metal material performance detection system based on longitudinal wave resonance provided in an embodiment of the present application.

[0061] Specific implementation methods In order to make the technical personnel in this technical field better understand the solution of this application, the technical solution in the embodiment of this application will be clearly and completely described below in combination with the drawings in the embodiment of this application. Obviously, the described embodiment is only a part of the embodiment of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0062] It should be noted that the terms such as "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a specific relationship or order between these entities or operations. It should be understood that the words "first", "second" and the like do not limit the quantity and execution order, and the words "first" and "second" and the like do not limit them to be necessarily different. It should be understood that the data used in this way can be interchanged under appropriate circumstances. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, article or device including a series of elements includes not only those elements clearly listed, but also other elements that are not clearly listed, or may also include elements inherent to such process, method, product or device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0063] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0064] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0065] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0066] In a first aspect of an embodiment of the present application, a method for detecting the properties of a metal material based on longitudinal wave resonance is provided, wherein the metal material properties are detected based on a laser and a metal material properties detection sensor, wherein the metal material properties detection sensor comprises an electromagnetic ultrasonic transducer EMAT (English: Electromagnetic Acoustic Transducer) and a magnetic focusing ring; the method comprises: placing the EMAT and the magnetic focusing ring on both sides of a metal material sample, respectively; the laser emitted by the laser passes through the magnetic focusing ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, which is finally received by the EMAT, and the performance of the metal material sample is detected based on the ultrasonic resonance signal received by the EMAT.

[0067] The method provided in the above embodiment utilizes the laser-electromagnetic ultrasonic longitudinal wave resonance method based on the material surface constraint mechanism to perform high-temperature material performance detection and safety assessment of hot end components.

[0068] The mechanism of laser-induced ultrasound is based on the power density of the incident light (10 7 W / cm 2 ) is divided into thermoelastic mechanism and ablation mechanism. The attenuation of longitudinal wave in metal is smaller than that of transverse wave, and the speed of longitudinal wave is faster than that of transverse wave. Theoretically, longitudinal wave has high signal-to-noise ratio and high resolution, and is a good choice for measuring the thickness of metal thin plates. Usually, the amplitude of longitudinal wave under ablation mechanism is greater than that of thermoelastic mechanism, but the amplitude of longitudinal wave under ablation mechanism is usually greater than 10 7 W / cm 2 When the energy density is irradiated on the metal, the pulsed laser beam will ablate the surface of the metal material sample and cause corrosion damage of several microns deep to the material in the irradiated area. Therefore, the present application proposes to adopt a surface constraint mechanism based on the thermoelastic mechanism, which can improve the efficiency of laser ultrasonic energy transfer, thereby achieving the effect of enhancing the longitudinal wave signal. Figure 1 This is an ultrasonic excitation diagram under the thermoelastic mechanism. When the incident light power density is low, the surface layer of the material absorbs the laser energy and converts it into thermal energy, causing thermal expansion and thus generating tangential pressure, while exciting longitudinal waves, shear waves and surface waves.

[0069] Figure 2The main principle of the surface constraint mechanism is that when the sample surface is covered by liquid or liquid-solid mixed material, the covering layer changes the elastic boundary conditions of the sample surface, making the sample surface non-free, that is, the stress σ at the vertical boundary i3 ≠0. In addition, since the cover layer usually has a larger thermal expansion coefficient than the solid, it will produce a larger thermoelastic stress and cause the solid to bear a larger normal stress. Since the shear wave cannot propagate in the liquid and the longitudinal wave mainly vibrates in the out-of-plane direction, the energy of the longitudinal wave is significantly improved, while the shear wave mainly vibrates in the in-plane direction, so the surface confinement mechanism in the laser excitation area cannot enhance its intensity.

[0070] Through research, it is found that the surface constrained longitudinal wave enhancement effect of using a liquid-solid mixed material with a certain viscosity (such as silver silicone grease) is better than water film constraint. Therefore, in the embodiment of the present application, a liquid-solid mixed material is used as a covering layer on the surface of the metal material sample to enhance the longitudinal wave signal and improve the signal-to-noise ratio.

[0071] The principle of the resonance method is: the laser-excited ultrasonic wave propagates back and forth on the thickness of the metal material sample. When the thickness of the metal material sample is an integer multiple of half the wavelength of the ultrasonic wave, the excitation wave and the reflected wave resonate inside the metal material sample, and the ultrasonic transmission energy will increase sharply, forming a superimposed signal with higher energy. The resonant frequency can be obtained by performing frequency domain analysis on the ultrasonic resonance signal received by the electromagnetic ultrasonic transducer EMAT. Laser ultrasound has the advantages of wide bandwidth of the excitation signal and rich wavelength content. Therefore, there will be multiple resonant frequencies within a given frequency range. Within the frequency band of the ultrasonic resonance signal, the difference between each resonant frequency point has a certain relationship with the thickness of the metal material sample. The difference between the pth resonant frequency point and the qth resonant frequency point can be expressed as:

[0072]

[0073] In formula (1), f p is the pth resonant frequency point, f q is the qth resonant frequency point, p>q≥1, d is the thickness of the metal material sample to be tested, and c is the ultrasonic sound velocity.

[0074] In other embodiments, the thickness of the metal material sample may be determined by other methods or measuring instruments, and then the ultrasonic velocity in the metal material sample may be calculated according to the above formula.

[0075] The embodiments of the present application also provide a method for characterizing the performance of a metal material sample. The impact of metal fatigue damage on acoustic properties has always been a long-standing problem in the field of acoustics. The appearance and expansion of dislocations and microcracks will have a certain impact on the sound velocity and sound attenuation inside metal materials. Dislocation refers to an internal microscopic defect of a crystalline material, that is, a local irregular arrangement of atoms. Due to viscosity and energy dissipation, dislocations will vibrate with phase lag under the action of ultrasonic waves, reducing the wave velocity of ultrasonic waves. At the same time, dislocations are also the main source of attenuation changes. In fatigue experiments, dislocations play an important role in the expansion of cracks and can produce extremely high stress areas at the tip of the crack.

[0076] According to the resonant frequency points of the resonant spectrum signal obtained above, at the resonant frequency points of different orders, the shape, size and amplitude of the resonant spectrum signal are closely related to the sound velocity and sound attenuation of the material. The sound velocity and sound attenuation inside the metal material sample (such as a metal sheet) will change in different damage states, and the sound velocity and sound attenuation are closely related to the dislocation density and length of the material. Accurately measuring the frequency point changes of the resonant spectrum signal and comparing them can achieve damage evaluation of the metal material sample. In addition, by measuring and drawing the resonant spectrum curve for the metal material sample, a resonant spectrum database of metal material samples in different damage states can be established, and the performance characterization of the metal material sample can be achieved by comparing the resonant spectrum database.

[0077] In some embodiments, the signal processing method of PSD analysis is applied to improve the signal-to-noise ratio of the detection signal of the laser-electromagnetic ultrasonic longitudinal wave resonance method. The electromagnetic ultrasonic sensor is a non-contact measurement during detection. The direction of the transducing magnetic field required for longitudinal wave detection is horizontal. Due to the influence of the permanent magnet magnetic circuit, when the lift-off changes, the horizontal magnetic field will be more affected. When the lift-off increases, the transducing efficiency will drop sharply. Therefore, the embodiment of the present application introduces a signal processing method to improve the signal-to-noise ratio of the detection signal and increase the spatial resolution. At the same time, the EMAT coil is easily affected by electromagnetic noise interference, resulting in a low signal-to-noise ratio of ultrasonic detection. Therefore, the signal processing method of PSD analysis is used on the basis of the ultrasonic resonance detection method to further improve the signal-to-noise ratio and variable lift-off detection capability of EMAT. When the PSD signal processing method is used, the ultrasonic resonance signal is firstly subjected to autocorrelation analysis, and the autocorrelation function R(m) of the ultrasonic resonance signal is defined as follows:

[0078]

[0079] In formula (2), s(n) and s(nm) represent the ultrasonic resonance signal values ​​of the nth and nmth sampling points respectively, 0≤m≤N-1, and N is the number of sampling points.

[0080] By using autocorrelation analysis, the interference of random noise can be significantly suppressed, because the autocorrelation of random noise at any position is zero except m = 0. Based on the autocorrelation function of the ultrasonic resonance signal, the power spectrum density function P(f) of the ultrasonic resonance signal can be expressed as:

[0081]

[0082] In formula (3), f is the frequency, W(m) is the window function, Δt is the sampling interval; -M to M represents the signal length truncated by the window function;

[0083] Among them, the window function W(m) can use a Hanning window, a Hamming window, a triangular window, a Gaussian window, etc., and there is no limitation on this in the embodiments of the present application.

[0084] The various resonant frequency points of the ultrasonic resonance signal are determined according to the power spectrum density function of the ultrasonic resonance signal.

[0085] In a second aspect of the embodiment of the present application, a metal material property detection sensor is provided, which is used in the above-mentioned metal material property detection method;

[0086] Among them, the metal material performance detection sensors include EMAT and magnetic ring;

[0087] The EMAT includes a base permanent magnet and a coil;

[0088] In some embodiments, Figure 3 As shown, the basic permanent magnet includes two square permanent magnets, a yoke and a coil; the yoke is arranged above the two square permanent magnets, and the coil is arranged in the middle of the lower part of the two square permanent magnets; the two square permanent magnets are arranged symmetrically and have opposite polarities, the upper half of the square permanent magnet on the left is magnetized to the S pole, and the lower half is magnetized to the N pole, and the upper half of the square permanent magnet on the right is magnetized to the N pole, and the lower half is magnetized to the S pole;

[0089] Correspondingly, the magnetic focusing ring is a radially magnetized annular permanent magnet, the left half of the magnetic focusing ring is magnetized to the N pole, and the right half is magnetized to the S pole.

[0090] In the above embodiment, the basic permanent magnet utilizes two permanent magnets that are symmetrical on the left and right and have opposite polarities, and is matched with a radially magnetized annular permanent magnet that allows the laser light path to pass through. Since the directions of the magnetic flux lines of the basic permanent magnet and the annular permanent magnet are consistent within the near-surface adhesion depth of the metal material sample, and do not affect the normal passage characteristics of the laser light path, the horizontal magnetic field can be further enhanced.

[0091] In other embodiments, Figure 4As shown, the basic permanent magnet includes a first permanent magnet, a second permanent magnet and a soft magnetic concentrator;

[0092] The first permanent magnet and the soft magnetic concentrator are cylindrical; the second permanent magnet is annular column;

[0093] The first permanent magnet, the second permanent magnet and the soft magnetic concentrator are coaxially arranged;

[0094] The first permanent magnet is placed on the soft magnetic concentrator;

[0095] The second permanent magnet and the soft magnetic concentrator are of equal height, and their bottom surfaces are on the same plane; the second permanent magnet is sleeved outside the soft magnetic concentrator;

[0096] The diameter of the soft magnetic concentrator is equal to the inner diameter of the second permanent magnet and smaller than the diameter of the first permanent magnet;

[0097] The second permanent magnet is magnetized in radial direction and is divided into an inner part and an outer part; the outer diameter of the inner part is larger than the diameter of the first permanent magnet; the inner diameter of the outer part is equal to the outer diameter of the inner part;

[0098] The first permanent magnet and the magnetic focusing ring correspondingly adopt a first magnetization structure:

[0099] The first permanent magnet is magnetized along the axial direction and is divided into two parts, the upper part is magnetized to an N pole, and the lower part is magnetized to an S pole;

[0100] The inner part of the second permanent magnet is magnetized to an S pole, and the outer part of the second permanent magnet is magnetized to an N pole;

[0101] Correspondingly, the magnetic focusing ring is an axially magnetized annular permanent magnet, the upper half of the magnetic focusing ring is magnetized to the N pole, and the lower half is magnetized to the S pole.

[0102] Alternatively, the first permanent magnet and the magnetic focusing ring correspondingly adopt a second magnetization structure:

[0103] The first permanent magnet is magnetized along the axial direction and is divided into an upper and a lower part, wherein the upper part is magnetized to an S pole and the lower part is magnetized to an N pole;

[0104] The inner part of the second permanent magnet is magnetized to an N pole, and the outer part of the second permanent magnet is magnetized to an S pole;

[0105] Correspondingly, the magnetic focusing ring is an axially magnetized annular permanent magnet, the upper half of the magnetic focusing ring is magnetized to the S pole, and the lower half is magnetized to the N pole.

[0106] In the above embodiment, the basic permanent magnet structure includes an axially magnetized cylindrical magnet, a soft magnetic concentrator made of soft magnetic material, and a radially (horizontally) magnetized annular cylindrical magnet, and ensures that all magnetic poles adjacent to the soft magnetic concentrator have the same polarity.

[0107] The configuration of the basic permanent magnet of EMAT and the magnetic focusing ring proposed in the above embodiments of the present application can enhance the magnetic field strength in the horizontal direction. Since the signal-to-noise ratio of EMAT is usually proportional to the square of the magnetic induction intensity, the signal-to-noise ratio will increase by nearly 50% when the magnetic induction intensity increases by nearly 20%, thereby obtaining a detection signal with a higher signal-to-noise ratio, thereby realizing large lift-off detection.

[0108] In some embodiments, the coil is a linear coil. The use of a linear coil is conducive to the Lorentz force transduction mechanism to receive longitudinal wave signals. The Lorentz force left-hand rule is used, and the magnetic flux provided by the permanent magnet passes through the palm, and the direction of the current is Figure 3 The ceramic block is marked in the middle, indicating the direction of the current flowing through the coil. The direction of the Lorentz force generated is vertical, and the vibration direction of the longitudinal wave particles is consistent with the propagation direction of the ultrasonic wave, that is, vertical vibration.

[0109] In some embodiments, Figure 5 As shown, the basic permanent magnet and coil of the EMAT are assembled in a shell with an opening at the front end; the coil adopts a ceramic silver coil resistant to high temperature of 800°C; a gel resistant to high temperature of 1000°C is filled between the shell and the basic permanent magnet and the coil; and a heat insulation film is provided between the coil and the front end of the shell.

[0110] In some embodiments, both the base permanent magnet and the magnetic focusing ring are made of SmCo permanent magnets that can withstand high temperatures of 350°C.

[0111] Therefore, the coil of EMAT adopts the combination of 800℃ high-temperature ceramic silver coil and 1000℃ high-temperature gel. The basic permanent magnet and the magnetic ring both adopt SmCo permanent magnet that can withstand 350℃, which further increases the high-temperature resistance of the sensor. After being assembled through the outer shell and isolating the coil with a high-temperature insulation film, the impact of temperature on the sensor can be further reduced, and continuous online monitoring of ultra-high temperature of 800℃ can be achieved.

[0112] like Figure 6 As shown, in a third aspect of the embodiment of the present application, a metal material property detection system based on longitudinal wave resonance is provided, comprising a laser and the above-mentioned metal material property detection sensor;

[0113] The laser is used as the excitation part, and the metal material performance detection sensor is used as the receiving part;

[0114] When in use, the laser emitted by the laser passes through the magnetic focusing ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, which is finally received by the EMAT; the metal material performance test results are calculated based on the ultrasonic resonance signal collected by the EMAT.

[0115] The system can be used to evaluate the performance of aerospace hot end components in high temperature and vibration environments.

[0116] In some embodiments, the laser is a solid pulse laser. For example, a Nimma series Q-switched Nd:YAG 1064nm solid pulse laser developed by ematech can be used.

[0117] The laser uses liquid cooling circulation to dissipate heat, can emit laser with a wavelength of 1064nm, stimulate ultrasonic waves through a thermoelastic mechanism, and use silver silicone grease to enhance the ultrasonic amplitude.

[0118] In some embodiments, the system also includes a multi-joint rotating mechanical light-guiding arm matched with the laser, which is used to realize three-dimensional light path deflection, so that the laser emitted by the laser passes through the magnetic focusing ring along the axis of the magnetic focusing ring and is emitted to the metal material sample, thereby improving the detection efficiency in complex environments.

[0119] In some embodiments, the multi-joint rotating shaft mechanical light-guiding arm contains a beam splitter inside, which, when combined with a 10-level attenuator of the laser, can achieve energy adjustment of 0.5mJ to 600mJ, which can meet the detection requirements.

[0120] In some embodiments, the system further includes two programmable robotic arms, which are respectively used to drive the EMAT, the light guide arm and the magnetic focusing ring to move, thereby realizing the function of path scanning of metal material samples.

[0121] EMAT performs scanning through a programmable robotic arm, and uses a human-computer interaction interface developed based on Labview to achieve automated scanning and data collection of planned paths.

[0122] The scanning function is achieved through a multi-joint rotating mechanical light-guiding arm and a programmable robotic arm, which can guide the laser to the area to be tested on the workpiece, thereby stimulating ultrasonic waves.

[0123] In some embodiments, the laser spot diameter is 8mm, the laser pulse width is 8ns, and the repetition frequency is 10Hz; the laser beam single pulse energy can be stably adjusted in the range of 0.5mJ to 600mJ by controlling the voltage (545V to 700V), a 10-level attenuator, and a spectroscope. For example, the laser beam single pulse energy is 185mJ corresponding to 600V, which does not reach the ablation threshold and does not damage the workpiece surface.

[0124] In some embodiments, the system further comprises a heating belt for heating the metal material sample, which can achieve a high temperature heating function above 1000°C.

[0125] In some embodiments, the system further includes a three-dimensional vibration platform for applying vibration to the metal material sample.

[0126] The metal material sample is heated by a high-temperature heating belt and matched with a three-dimensional vibration platform. The metal material sample is wrapped with thermal insulation cotton, which can simulate the complex working environment of high temperature vibration.

[0127] In some embodiments, the system further includes an impedance matcher, an OLYMPUS 5072PR preamplifier, a data acquisition card, and a computer connected in sequence. The impedance matching module is used to adjust the matching capacitance and inductance parameters of the EMAT coil, improve the amplitude and signal-to-noise ratio of the received ultrasonic resonance signal, and increase the bandwidth of the ultrasonic resonance signal to obtain an ultrasonic resonance signal with a high-frequency bandwidth of the signal-to-noise ratio. The ultrasonic resonance signal then passes through the preamplifier and the data acquisition card, and the data acquisition card transmits the signal to the computer. After further processing using the PSD, the required high signal-to-noise ratio resonance spectrum signal can be obtained.

[0128] Among them, the preamplifier can use OLYMPUS 5072PR preamplifier.

[0129] The laser-electromagnetic ultrasonic longitudinal wave resonance detection technology based on the material surface constraint mechanism proposed in the embodiment of the present application uses a laser to excite an ultrasonic signal on the metal material sample to be tested, and the EMAT receives the ultrasonic resonance signal; the laser-electromagnetic ultrasonic detection technology combines the advantages of wide bandwidth, high efficiency and high precision of laser ultrasonic detection, high detection sensitivity, and is suitable for long-distance non-contact detection. At the same time, it combines the advantages of simple sensor structure design, low manufacturing cost and high detection stability of electromagnetic ultrasonic detection technology. The longitudinal wave resonance method based on the material surface constraint mechanism is used to perform corrosion thinning test on the metal wall, which can solve the problem of low signal-to-noise ratio of laser electromagnetic ultrasonic detection technology and greatly improve spatial resolution, and can realize metal wall corrosion thinning detection under harsh environments such as high temperature. Using silver silicone grease for surface constraint mechanism can greatly increase the amplitude of the detection signal and improve the signal-to-noise ratio of the detection signal. In addition, the embodiment of the present application proposes two new basic magnet configuration forms and adds a magnetic focusing ring to further optimize and improve the performance of EMAT, which can realize non-contact detection with large lift-off, and the detection signal is not affected by the vibration environment. Under the working conditions of large lift-off, the use of high-temperature resistant SmCo permanent magnets and high-temperature design treatment of EMAT can achieve ultra-high temperature continuous online monitoring, and can perform online detection of corrosion thinning damage on metal workpieces such as aerospace engine turbine blades and tail nozzles in harsh environments such as high temperature, vibration and corrosion. Based on the configuration of the basic permanent magnet of the new EMAT with a magnetic ring, the power spectral density (PSD) algorithm is used to further reduce the noise of the detection signal, and reliable data for corrosion thinning monitoring of engine turbine blades and tail nozzles under harsh conditions such as high temperature and vibration can be obtained.

[0130] The above description of the embodiments of the present application is only a partial embodiment of the present application, which is used to enable professionals in the field to implement or use the content of the present application, and is not used to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for detecting metal material properties based on longitudinal wave resonance, characterized in that: Metal material performance detection is performed based on a laser and a metal material performance detection sensor, wherein the metal material performance detection sensor includes an electromagnetic ultrasonic transducer (EMAT) and a magnetic focusing ring; the method includes: placing the EMAT and the magnetic focusing ring on both sides of the metal material sample respectively; laser light emitted by the laser passes through the magnetic focusing ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, which is finally received by the EMAT, and the performance of the metal material sample is detected based on the ultrasonic resonance signal received by the EMAT.

2. The method according to claim 1, characterized in that: The liquid-solid mixed material covering the surface of the metal material sample is silver silicone grease.

3. The method according to claim 1, characterized in that The method of detecting the performance of the metal material sample based on the ultrasonic resonance signal received by the EMAT comprises: Performing power spectral density (PSD) analysis on the ultrasonic resonance signal received based on EMAT to obtain a power spectral density function of the ultrasonic resonance signal; Determine each resonant frequency point of the ultrasonic resonant signal according to the power spectrum density function; Based on each resonant frequency point, the thickness of the metal material sample to be tested is calculated according to the following formula: Among them, f p is the pth resonant frequency point, f q is the qth resonant frequency point, p>q≥1, d is the thickness of the metal material sample to be tested, and c is the ultrasonic sound velocity.

4. A metal material performance detection sensor, characterized in that: A method for detecting the performance of a metal material as claimed in any one of claims 1 to 3; The metal material performance detection sensor includes an EMAT and a magnetic focusing ring; The EMAT comprises a base permanent magnet and a coil; The basic permanent magnet includes two square permanent magnets, a yoke and a coil; the yoke is arranged above the two square permanent magnets, and the coil is arranged in the middle of the lower part of the two square permanent magnets; the two square permanent magnets are arranged symmetrically and have opposite polarities, the upper half of the square permanent magnet on the left is magnetized to the S pole, and the lower half is magnetized to the N pole, and the upper half of the square permanent magnet on the right is magnetized to the N pole, and the lower half is magnetized to the S pole; Correspondingly, the magnetic focusing ring is a radially magnetized annular permanent magnet, the left half of the magnetic focusing ring is magnetized to the N pole, and the right half is magnetized to the S pole.

5. A metal material performance detection sensor, characterized in that: A method for detecting the performance of a metal material as claimed in any one of claims 1 to 3; The metal material performance detection sensor includes an EMAT and a magnetic focusing ring; The EMAT comprises a base permanent magnet and a coil; The basic permanent magnet includes a first permanent magnet, a second permanent magnet and a soft magnetic concentrator; The first permanent magnet and the soft magnetic concentrator are cylindrical; the second permanent magnet is annular column; The first permanent magnet, the second permanent magnet and the soft magnetic concentrator are coaxially arranged; The first permanent magnet is placed on the soft magnetic concentrator; The second permanent magnet and the soft magnetic concentrator are of equal height, and their bottom surfaces are on the same plane; the second permanent magnet is sleeved outside the soft magnetic concentrator; The diameter of the soft magnetic concentrator is equal to the inner diameter of the second permanent magnet and smaller than the diameter of the first permanent magnet; The second permanent magnet is magnetized in radial direction and is divided into an inner part and an outer part; the outer diameter of the inner part is larger than the diameter of the first permanent magnet; the inner diameter of the outer part is equal to the outer diameter of the inner part; The first permanent magnet and the magnetic focusing ring correspondingly adopt a first magnetization structure: The first permanent magnet is magnetized along the axial direction and is divided into two parts, the upper part is magnetized to an N pole, and the lower part is magnetized to an S pole; The inner part of the second permanent magnet is magnetized to an S pole, and the outer part of the second permanent magnet is magnetized to an N pole; Correspondingly, the magnetic focusing ring is an axially magnetized annular permanent magnet, the upper half of the magnetic focusing ring is magnetized to the N pole, and the lower half is magnetized to the S pole. Alternatively, the first permanent magnet and the magnetic focusing ring correspondingly adopt a second magnetization structure: The first permanent magnet is magnetized along the axial direction and is divided into an upper and a lower part, wherein the upper part is magnetized to an S pole and the lower part is magnetized to an N pole; The inner part of the second permanent magnet is magnetized to an N pole, and the outer part of the second permanent magnet is magnetized to an S pole; Correspondingly, the magnetic focusing ring is an axially magnetized annular permanent magnet, the upper half of the magnetic focusing ring is magnetized to the S pole, and the lower half is magnetized to the N pole.

6. The method according to claim 4 or 5, characterized in that: The coil is a linear coil.

7. The method according to claim 4 or 5, characterized in that: The basic permanent magnet and coil of the EMAT are assembled in a shell with an opening at the front end; the coil is a ceramic silver coil resistant to high temperatures of 800°C; a gel resistant to high temperatures of 1000°C is filled between the shell and the basic permanent magnet and coil; a heat insulation film is provided between the coil and the front end of the shell; The basic permanent magnet and the magnetic focusing ring are both made of SmCo permanent magnets that can withstand a high temperature of 350°C.

8. A metal material performance detection system based on longitudinal wave resonance, characterized in that: It comprises a laser and a metal material property detection sensor as described in any one of claims 5 to 7; The laser is used as the excitation part, and the metal material performance detection sensor is used as the receiving part; When in use, the laser emitted by the laser passes through the magnetic focusing ring and the liquid-solid mixed material covering the surface of the metal material sample to generate an ultrasonic resonance signal in the metal material sample, which is finally received by the EMAT; the metal material performance test results are calculated based on the ultrasonic resonance signal collected by the EMAT.

9. The method according to claim 8, characterized in that The system also includes a multi-joint rotating shaft mechanical light guide arm matched with the laser, which is used to realize three-dimensional light path deflection, so that the laser light emitted by the laser passes through the magnetic focusing ring along the axial direction of the magnetic focusing ring and is emitted to the metal material sample; The system also includes two programmable robotic arms, which are used to drive the EMAT and the magnetic focusing ring to move respectively, so as to realize the function of path scanning of the metal material sample.

10. The method according to claim 9, characterized in that The system also includes an impedance matcher, a preamplifier, a data acquisition card and a computer connected in sequence; wherein the impedance matching module is used to adjust the matching capacitance and inductance parameters of the EMAT coil, thereby increasing the amplitude and signal-to-noise ratio of the received ultrasonic resonance signal and the frequency bandwidth of the ultrasonic resonance signal; the preamplifier is used to process the ultrasonic resonance signal, and the data acquisition card transmits the amplified ultrasonic resonance signal to the computer, and the computer is used to perform PSD analysis on the received ultrasonic resonance signal to obtain the power spectrum density function of the ultrasonic resonance signal, that is, the resonance spectrum signal.

Images