Phase-control multichannel nonlinear ultrasonic nondestructive testing system and method based on phase reversal excitation

Abstract

The invention discloses a phase-control multi-channel nonlinear ultrasonic nondestructive testing system and method based on phase reversal excitation, and the method comprises the steps: generating multi-channel phase reversal waveform data and a control instruction by an upper computer, carrying out the nonlinear parameter extraction of a received digital signal, and calculating a nondestructive testing result; the phase-control high-energy fundamental frequency ultrasonic excitation module suppresses a fundamental frequency signal for the electric signal with the phase reversal waveform, enhances the harmonic amplitude, and performs delay excitation to realize fixed-point focusing; the transmitting transducer array and the receiving transducer array convert the electric signal and the acoustic signal; the multi-path double-band-pass filter is used for carrying out fundamental wave suppression, harmonic wave enhancement and clutter filtering to enhance a nonlinear effect and improve a signal-to-noise ratio; and the phase-controlled ultrasonic acquisition module is used for filtering, amplifying and sampling the multi-channel feedback electric signal and converting the multi-channel feedback electric signal into a digital signal. The method has the multi-channel nonlinear ultrasonic evaluation capability, can realize multi-channel phase reversal waveform excitation, has the ultrasonic fixed-point focusing capability, and remarkably improves the nonlinear effect detection result, so that the detection result is more accurate.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic non-destructive testing, and particularly relates to a phased multi-channel non-linear ultrasonic non-destructive testing system and method based on phase reversal excitation. Background Art

[0002] In many fields such as industry and medicine, there are generally components serving under special conditions such as high temperature, high pressure, and high corrosiveness. Under extreme conditions, components serving under high strength will inevitably suffer damage. Therefore, timely detecting the early micro-damage of components and accurately evaluating the development stage of the damage are of great significance for maintaining overall safety and stability.

[0003] As a non-linear factor, micro-damage will enhance the non-linear effect of materials. This non-linear effect can be reflected by non-linear ultrasonic methods, so as to realize the detection and evaluation of micro-damage. In recent years, the combination of non-linear ultrasonic technology and phased ultrasonic technology has formed phased non-linear ultrasonic non-destructive testing technology, providing a feasible solution for the detection and imaging of micro-damage.

[0004] However, the non-linear components in ultrasonic signals are much lower than the fundamental wave components. During actual measurement, factors such as contact pressure, couplant type, and application method will also increase the attenuation of ultrasonic signals and introduce non-linear components. These reasons make it difficult to detect non-linear ultrasonic signals.

[0005] In addition, the existing non-linear ultrasonic non-destructive testing systems are separate ultrasonic non-destructive testing systems built based on devices such as oscilloscopes, signal generators, linear power amplifiers, filters, attenuators, and computers. Although they can meet the requirements of high-voltage excitation, they cannot achieve complex waveform excitation and phased excitation and reception functions; traditional phased ultrasonic testing systems can achieve phased excitation and reception, but the excitation voltage is insufficient and they are not sensitive to non-linear effects. Summary of the Invention

[0006] To solve the above problems, the object of the present invention is to provide a phased multi-channel non-linear ultrasonic non-destructive testing system and method based on phase reversal excitation, realizing an integrated and easy-to-operate non-linear ultrasonic non-destructive testing system with functions of high-voltage phase reversal waveform excitation, phased transmission and reception, and accurate detection of non-linear effects.

[0007] The technical solution provided by the present invention is: A phased multi-channel non-linear ultrasonic non-destructive testing system based on phase reversal excitation, comprising: A host computer, which generates multi-channel phase reversal waveform data and configuration control instructions, extracts information in the time domain - frequency domain - space domain from the received digital signals, and calculates non-linear parameters to mark the non-destructive testing results of non-linear ultrasonic of the material to be tested; The phased high-energy fundamental frequency ultrasonic excitation module generates an electrical signal with a multi-channel phase-reversed waveform according to the control instruction of the host computer to suppress the fundamental frequency signal and enhance the harmonic amplitude, and performs delayed excitation on different channels according to the timing control instruction for ultrasonic fixed-point focusing, and then performs linear amplification processing on the electrical signal with the multi-channel phase-reversed waveform; The multi-channel low-pass analog filter is used for filtering at the transmitting end to reduce the influence of harmonic components at the transmitting end; The transmitting transducer array is configured to be coupled with the material to be measured through a coupling agent, convert the amplified electrical signal into an ultrasonic signal and act on the material to be measured; The receiving transducer array is configured to be coupled with the material to be measured through a coupling agent, and convert the ultrasonic signal received from the material to be measured into an electrical signal; The multi-channel dual-bandpass filter suppresses the fundamental wave and enhances the harmonics of the electrical signal converted by the receiving transducer array, and filters out clutter at the same time to enhance the nonlinear effect of the received signal and further improve the signal-to-noise ratio; The phased ultrasonic acquisition module filters, amplifies and samples the electrical signal fed back by the multi-channel dual-bandpass filter according to the control instruction of the host computer to convert it into a digital signal, and sends the digital signal to the host computer.

[0008] Preferably, the phased high-energy fundamental frequency ultrasonic excitation module includes a multi-channel digital-to-analog converter and a multi-channel linear amplifier. The multi-channel digital-to-analog converter is used to generate the phase-reversed waveform of each channel, and the multi-channel linear amplifier linearly amplifies the electrical signal with the multi-channel phase-reversed waveform; Among them, the excitation of the phase-reversed waveform is calculated by the host computer according to the waveform to be excited to obtain the corresponding waveform data, which is sent to the register of the multi-channel digital-to-analog converter. The multi-channel digital-to-analog converter generates the corresponding waveform excitation according to the waveform data in the register. The phase-reversed waveform data of each channel is excited in the following way: If the initial input signal is , then the excitation waveform of all channels for the first time is: , The excitation waveform of all channels for the second time is: , For the anti-phase signal, the odd-frequency components have a 180-degree phase shift relative to the positive phase, and the even-frequency components have the same phase, thereby suppressing the fundamental frequency component and increasing the second harmonic amplitude.

[0009] Preferably, the phased high-energy fundamental frequency ultrasonic excitation module performs ultrasonic fixed-point focusing by performing delayed excitation on different channels based on the timing control instruction. The delay time of each channel is calculated in the following way: , Among them is the The distance from the channel to the focal point is the maximum distance from all channels to the focal point, C is the speed of sound, and the initial input signal is , then the input signal of the -th channel is: .

[0010] Preferably, the host computer calculates the corresponding waveform data according to the waveform to be excited, calculates the excitation timing instructions corresponding to different channels according to the position of the focal point, and then sends the waveform data and timing instructions to the phased high-energy fundamental frequency ultrasonic excitation module.

[0011] Preferably, the host computer receives the digital signal sent by the phased ultrasonic acquisition module, superimposes the acquisition results before and after phase flipping and calculates the amplitude spectrum and nonlinear parameters of the signals of each receiving channel, and compares the nonlinear parameters with the relationship between the nonlinear parameters and the damage degree of the material to be measured in the standard database to obtain the damage detection result of the material to be measured; wherein the nonlinear parameter is calculated as follows: Solving the wave propagation formula of the nonlinear wave equation at different positions, we can get: where u is the displacement, n is different channels, β is the second-order nonlinear parameter, w is the frequency, k is the wave number, and A is the fundamental wave amplitude; The nonlinear parameter is calculated using the following formula: where B is the second harmonic amplitude.

[0012] Preferably, the initial input waveform is a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses, the frequency is 2.4 MHz, and the waveform data including timing can be calculated by the following formula: where A is the amplitude, is the center frequency of the sine wave, is the Hanning window envelope, T is the total time length, is the specific delay time of each channel, where is the -th channel to the focal point distance, is the maximum distance from all channels to the focal point, and C is the speed of sound; Based on the phase inversion theory, the excitation waveform of all channels for the first time is: The excitation waveform of all channels for the second time is: The phased high-energy fundamental frequency ultrasonic excitation module generates a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses of different phases according to the instructions of the host computer, and performs delayed excitation on different channels according to the timing control instructions to achieve ultrasonic fixed-point focusing, and then performs linear amplification processing on the signal to make the peak-to-peak value of the excitation waveform reach 190V.

[0013] Preferably, the multi-channel dual-bandpass filter includes a bandpass filter and a bandstop filter, and by adjusting the parameters of the filter, the fundamental wave of the ultrasonic signal is suppressed, the harmonics are enhanced, and the clutter is filtered out at the same time.

[0014] Preferably, the phased ultrasonic acquisition module includes a multi-channel ultrasonic analog front end and a high-speed acquisition module. The multi-channel ultrasonic analog front end has a maximum gain of 48dB and a maximum resolution of 16bit to achieve precise measurement of small signals. The high-speed acquisition module is built based on FPGA and adopts the JESD204B interface protocol to achieve fast signal acquisition.

[0015] Preferably, both the transmitting transducer array and the receiving transducer array include 16 elements arranged linearly, and the transmitting transducer array and the receiving transducer array are placed perpendicular or parallel to each other.

[0016] Based on the same concept, the present invention also provides a phased multi-channel non-destructive testing method for nonlinear ultrasonic based on phase inversion excitation. The detection system includes the following steps: Calculate the multi-channel phase inversion waveform data through the host computer, calculate the excitation timing instructions corresponding to different channels according to the position of the focusing point, and send the multi-channel phase inversion waveform data and timing instructions to the phased high-energy fundamental frequency ultrasonic excitation module; Generate an electrical signal with a multi-channel phase inversion waveform based on the control instructions of the host computer through the phased high-energy fundamental frequency ultrasonic excitation module to suppress the fundamental frequency signal and enhance the harmonic amplitude, and perform delayed excitation on different channels based on the timing control instructions for ultrasonic fixed-point focusing, and then perform linear amplification processing on the electrical signal with the multi-channel phase inversion waveform; Perform filtering at the transmitting end through a multi-channel low-pass analog filter to reduce the influence of harmonic components at the transmitting end; Convert the amplified electrical signal into an ultrasonic signal through the transmitting transducer array and act on the material to be tested; Convert the ultrasonic signal received from the material to be tested into an electrical signal through the receiving transducer array; Perform fundamental wave suppression, harmonic enhancement and clutter filtering on the electrical signal converted by the receiving transducer array through a multi-channel dual-bandpass filter to enhance the nonlinear effect of the received signal and further improve the signal-to-noise ratio; The phased ultrasound acquisition module filters, amplifies, and samples the electrical signals fed back by the multi-channel dual-bandpass filters based on the host computer control instructions to convert them into digital signals, and sends the digital signals to the host computer; The host computer extracts information in the time domain - frequency domain - spatial domain from the received digital signals, and calculates non-linear parameters to mark the non-linear ultrasonic non-destructive testing results of the material to be tested.

[0017] Due to the adoption of the above technical solutions, the present invention has the following advantages and positive effects compared with the prior art: By using the phase inversion waveform, the fundamental frequency signal can be effectively suppressed and the harmonic amplitude can be enhanced, thereby improving the detection ability for micro defects. Compared with the traditional single-channel non-linear ultrasonic non-destructive testing system, it can perform scanning inspections within a certain range, with shorter detection time and more accurate results. At the same time, the multi-channel design enables the system to detect the material to be tested from multiple angles, further improving the detection resolution. By delaying the excitation of different channels according to the timing control instructions, fixed-point ultrasonic focusing measurement at any position of interest of the material to be tested can be achieved. The multi-channel low-pass analog filter is used for filtering at the transmitting end, which can effectively reduce the influence of harmonic components at the transmitting end, thereby reducing the background noise and improving the signal quality. The multi-channel dual-bandpass filter not only suppresses the fundamental wave signal and enhances the harmonic signal, but also filters out clutter, which can significantly enhance the non-linear effect of the received signal, contribute to more accurately identifying the non-linear characteristics of the material, realize high-energy phase inversion waveform excitation, or other high-energy arbitrary waveform excitations, while enhancing the non-linear effect and reducing the harmonic interference at the excitation end. Through the multi-channel dual-bandpass filter, while suppressing the fundamental wave and enhancing the harmonics, other frequency components of clutter are filtered out, enhancing the non-linear effect of the received signal and further improving the signal-to-noise ratio. Through the above measures, the signal-to-noise ratio of the system has been significantly improved, and useful signals can be detected more clearly even in the presence of noise, which is particularly important for applications in complex environments. Description of the Drawings

[0018] The following further details the specific embodiments of the present invention with reference to the drawings, where: Figure 1 is the structural block diagram of the phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation of the present invention; Figure 2 is the step of performing non-destructive testing and evaluation using the phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation in an embodiment of the present invention; Figure 3 is the layout schematic diagram of the transmitting transducer array and the receiving transducer array in an embodiment of the present invention; Figure 4Schematic diagram of the amplitude-frequency curve simulation of the multi-channel dual-bandpass filter according to an embodiment of the present invention.

[0019] Explanation of reference numerals: 1 - Transmitting transducer array; 2 - Microdamage; 3 - Material to be tested; 4 - Receiving transducer array. Specific embodiments

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. According to the following description and the claims, the advantages and features of the present invention will be more clearly understood. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, only for the purpose of facilitating and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0022] See Figure 1 , the technical solution of this embodiment provides a phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation, including: A host computer that generates multi-channel phase inversion waveform data and configuration control instructions, extracts information in the time domain - frequency domain - space domain from the received digital signals, and calculates non-linear parameters to mark the non-linear ultrasonic non-destructive testing results of the material 3 to be tested; A phased high-energy fundamental frequency ultrasonic excitation module that generates electrical signals with multi-channel phase inversion waveforms according to the control instructions of the host computer to suppress the fundamental frequency signal and enhance the harmonic amplitude, and performs delayed excitation on different channels according to the timing control instructions for ultrasonic fixed-point focusing, and then performs linear amplification processing on the electrical signals with multi-channel phase inversion waveforms; A multi-channel low-pass analog filter for filtering at the transmitting end to reduce the influence of harmonic components at the transmitting end; A transmitting transducer array 1 configured to be coupled to the material 3 to be tested through a coupling agent, convert the amplified electrical signal into an ultrasonic signal and act on the material 3 to be tested; A receiving transducer array 4 configured to be coupled to the material 3 to be tested through a coupling agent, and convert the ultrasonic signal received from the material 3 to be tested into an electrical signal; A multi-channel dual-bandpass filter that suppresses the fundamental wave and enhances the harmonics of the electrical signal converted by the receiving transducer array 4 while filtering out clutter to enhance the non-linear effect of the received signal and further improve the signal-to-noise ratio; The phased ultrasound acquisition module filters, amplifies, and samples the electrical signals fed back by the multi-channel band-pass filters according to the host computer control instructions to convert them into digital signals, and sends the digital signals to the host computer.

[0023] The technical solution of this embodiment can effectively suppress the fundamental frequency signal and enhance the harmonic amplitude by using the phase inversion waveform, thereby improving the detection ability for microdamage 2. Compared with the traditional single-channel non-linear ultrasonic non-destructive testing system, it can perform scanning inspections within a certain range, with shorter detection time and more accurate results. At the same time, the multi-channel design enables the system to detect the material to be measured 3 from multiple angles, further improving the detection resolution. By delaying the excitation of different channels according to the timing control instructions, fixed-point ultrasonic focusing measurement at any position of interest on the material to be measured 3 can be achieved. The multi-channel low-pass analog filter is used for filtering at the transmitting end, which can effectively reduce the influence of harmonic components at the transmitting end, thereby reducing background noise and improving the signal quality. The multi-channel band-pass filter not only suppresses the fundamental wave signal and enhances the harmonic signal, but also filters out clutter, which can significantly enhance the non-linear effect of the received signal, helps to more accurately identify the non-linear characteristics of the material, realizes high-energy phase inversion waveform excitation, or other high-energy arbitrary waveform excitations, while enhancing the non-linear effect and reducing the harmonic interference at the excitation end. Through the multi-channel band-pass filter, while suppressing the fundamental wave and enhancing the harmonics, other frequency components of clutter are filtered out, enhancing the non-linear effect of the received signal and further improving the signal-to-noise ratio. Through the above measures, the signal-to-noise ratio of the system has been significantly improved, and useful signals can be detected more clearly even in the presence of noise, which is particularly important for applications in complex environments.

[0024] Preferably, the phased high-energy fundamental frequency ultrasound excitation module includes a multi-channel digital-to-analog converter and a multi-channel linear amplifier. The multi-channel digital-to-analog converter is used to generate the phase inversion waveforms of each channel, and the multi-channel linear amplifier linearly amplifies the electrical signals of the multi-channel phase inversion waveforms; Among them, the excitation of the phase inversion waveform is calculated by the host computer according to the waveform to be excited to obtain the corresponding waveform data, which is sent to the register of the multi-channel digital-to-analog converter. The multi-channel digital-to-analog converter generates the corresponding waveform excitation according to the waveform data in the register. The phase inversion waveform data of each channel is excited in the following manner: If the initial input signal is , then the excitation waveforms of all channels for the first time are: , The excitation waveforms of all channels for the second time are: , For the anti-phase signal, the odd-frequency components (fundamental wave, third harmonic, etc.) have a 180-degree phase shift relative to the positive phase, and the even-frequency components (second harmonic, etc.) have a 360-degree phase shift, that is, the same phase, thus suppressing the fundamental frequency component and increasing the second harmonic amplitude.

[0025] The host computer calculates the corresponding waveform data according to the waveform to be excited and sends it to the register of the multi-channel digital-to-analog converter. This process allows for precise definition and adjustment of the waveform. According to different detection requirements, such as the characteristics of the material 3 to be measured, the size of the detection target, etc., the waveform data can be flexibly changed to achieve the best detection effect. In this way, a waveform with phase inversion characteristics can be accurately generated, providing a high-quality excitation signal for subsequent ultrasonic detection. For the initial input signal, during the process of exciting the waveform for the first and second times in all channels, the odd-frequency components have a 180-degree phase shift relative to the positive phase, and the even-frequency components have the same phase. This precise phase control helps to suppress the fundamental frequency component and increase the second harmonic amplitude. The accuracy of the phase shift enables the system to more effectively highlight the nonlinear characteristics of the material and improve the detection sensitivity to micro-damage 2 or damage inside the material. Through the 180-degree phase shift of the odd-frequency components, the fundamental frequency component is effectively suppressed. The fundamental frequency component may mask the nonlinear characteristics of the material in some cases, and suppressing the fundamental frequency component helps to highlight the nonlinear changes caused by defects or damage in the material. At the same time, increasing the second harmonic amplitude can provide more information about the material characteristics. The change of the second harmonic is often related to the change of the microstructure of the material. By enhancing the second harmonic amplitude, the nonlinear effect of the material can be better detected, and the accuracy of evaluating the internal state of the material can be improved.

[0026] Preferably, the phased high-energy fundamental frequency ultrasonic excitation module performs ultrasonic fixed-point focusing by delaying the excitation of different channels based on the timing control instruction. The delay time of each channel is calculated as follows: , where is the distance from the channel to the focus point, is the maximum distance from all channels to the focus point, C is the sound speed, the initial input signal is , then the input signal of the channel is: .

[0027] The delay time is calculated using a formula based on the distance from each channel to the focal point, the maximum distance from all channels to the focal point, and the speed of sound. This method accurately determines the excitation moment for each channel, ensuring that the ultrasonic energy is accurately superimposed at the predetermined focal point. The focal point can be flexibly adjusted for different locations and depths, enabling the system to achieve efficient fixed-point detection in different application scenarios. Based on precise delay time control, the ultrasonic signal can achieve more accurate and concentrated energy convergence at the focal point. Compared with traditional focusing methods, this method can produce a stronger focusing effect and improve the spatial resolution of detection. For complex shapes or internal structures of test materials, it can better achieve targeted detection and reduce energy diffusion and loss. The adjusted input signal can better meet the operating requirements of the phased high-energy fundamental frequency ultrasonic excitation module. When the signals from different channels reach the focal point, more accurate waveform control and energy excitation can be achieved, improving the detection performance of the entire system. Input signal parameters, such as amplitude and frequency, can be further optimized according to specific detection requirements and material properties to improve detection sensitivity and accuracy.

[0028] Preferably, the host computer calculates the corresponding waveform data according to the waveform to be excited, calculates the excitation timing instructions corresponding to different channels according to the position of the focal point, and then sends the waveform data and timing instructions to the phase-controlled high-energy fundamental frequency ultrasonic excitation module.

[0029] The close collaboration between the host computer and the phased high-energy fundamental frequency ultrasonic excitation module enables precise control of waveforms and timing. While the host computer handles calculations and planning, the excitation module ensures accurate execution. Their collaborative work improves overall system performance. This collaborative approach enables the system to better address diverse testing needs, enhancing flexibility and adaptability.

[0030] Preferably, the host computer receives the digital signal sent by the phase-controlled ultrasonic acquisition module, superimposes the acquisition results twice before and after the phase flip, calculates the amplitude spectrum and nonlinear parameters of the signal of each receiving channel, compares the nonlinear parameters with the relationship between the nonlinear parameters and damage degree of the material 3 to be tested in the standard database, and obtains the damage detection result of the material 3 to be tested; The nonlinear parameters are calculated as follows: Solving the nonlinear wave equation to the wave propagation formula at different positions, we can obtain: Where u is the displacement, n is the different channels, β is the second-order nonlinear parameter, w is the frequency, k is the wave number, and A is the fundamental amplitude; The nonlinear parameters are calculated using the following formula: where B is the amplitude of the second harmonic.

[0031] The host computer receives the digital signals sent by the phased array ultrasonic acquisition module and superimposes the acquisition results before and after phase inversion. In this way, the effective signals can be enhanced while reducing the influence of noise and interference, and the signal-to-noise ratio can be improved. By calculating the amplitude spectrum and nonlinear parameters of the signals of each receiving channel, the characteristics of the signals can be analyzed more comprehensively. The amplitude spectrum reflects the energy distribution of the signal at different frequencies, while the nonlinear parameters provide information about the changes in the internal structure of the material. By comparing the calculated nonlinear parameters with the relationship between the nonlinear parameters and the damage degree of the material to be measured No. 3 in the standard database, accurate damage detection results can be obtained. This method can effectively distinguish different degrees of damage and improve the accuracy of damage identification. By comparing with the standard database, the type and degree of damage can be quickly determined, providing a basis for taking corresponding maintenance or repair measures. By using the wave propagation formula of the solution of the nonlinear wave equation at different positions to calculate the nonlinear parameters, the characteristic information of the material can be obtained quickly and accurately. This method has high computational efficiency and can complete the processing of a large amount of data in a short time. At the same time, by analyzing the signals of different channels, multiple data points can be processed simultaneously, further improving the speed of data processing. The host computer can conveniently process and store the received data, and establish a perfect data management system. Historical data can be called at any time according to needs for comparison and analysis, providing support for long-term monitoring and prediction. By deeply analyzing the data, potential problems and trends can also be found, and preventive measures can be taken in advance to avoid accidents.

[0032] Preferably, in one embodiment, the initial input waveform is a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses, and the frequency is 2.4 MHz. The waveform data including the time sequence can be calculated by the following formula: where A is the amplitude, is the center frequency of the sine wave, is the Hanning window envelope, T is the total time length, is the specific delay time of each channel, where is the distance from the channel to the focal point, is the maximum distance from all channels to the focal point, and C is the sound speed; Based on the phase inversion theory, the waveform excited by all channels for the first time is: The phased high-energy fundamental frequency ultrasonic excitation module generates a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses of different phases according to the instructions of the host computer, and performs delayed excitation on different channels according to the timing control instructions to achieve ultrasonic fixed-point focusing, and then linearly amplifies the signal to make the peak-to-peak value of the excitation waveform reach 190V.

[0033] A high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses is used as the initial input waveform, and the frequency is 2.4 MHz. The Hanning window modulation can make the signal have smooth rising and falling edges in the time domain, reduce spectral leakage, and improve the spectral purity of the signal. The selection of this specific waveform helps to generate a clearer and more accurate signal response in ultrasonic detection and improve the resolution of the internal structure of the material. Based on the phase inversion theory, two waveform excitations are performed. The designs of the first and second excitation waveforms can be based on the acoustic characteristics of the material and the detection requirements to enhance the sensitivity to internal defects or structural features of the material. By precisely controlling the phase inversion of the waveform, better control over the propagation and reception of ultrasonic signals can be achieved, improving the accuracy and reliability of detection. The waveform data including timing is calculated by a formula, taking into account the specific delay time of each channel. According to factors such as the distance from the channel to the focus point, the maximum distance from all channels to the focus point, and the sound velocity, the delay time of each channel is accurately calculated. This precise timing control can ensure the accurate superposition of ultrasonic signals at the focus point, improving the focusing effect and accuracy. The phased high-energy fundamental frequency ultrasonic excitation module generates a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses of different phases according to the instructions of the host computer, and performs delayed excitation on different channels according to the timing control instructions to achieve ultrasonic fixed-point focusing. This method can precisely control the position of the ultrasonic focus in three-dimensional space and improve the detection ability of specific positions inside the material.

[0034] Preferably, the multi-channel dual-bandpass filter includes a bandpass filter and a bandstop filter, and by adjusting the parameters of the filter, the fundamental wave of the ultrasonic signal is suppressed, the harmonics are enhanced, and the clutter is filtered out at the same time.

[0035] A multi-channel dual-bandpass filter is adopted, which includes a bandpass filter and a bandstop filter. The bandpass filter allows signals within a specific frequency range to pass through while blocking signals of other frequencies; the bandstop filter is the opposite, it blocks signals within a specific frequency range and allows signals of other frequencies to pass through. This configuration can more flexibly control the frequency components of ultrasonic signals and achieve precise filtering of the fundamental wave and harmonics. In one embodiment, the two passbands of the multi-channel dual-bandpass filter are respectively set near the fundamental wave (2.4 MHz) and the second harmonic frequency (4.8 MHz).

[0036] Preferably, the phased ultrasound acquisition module includes a multi-channel ultrasound analog front end and a high-speed acquisition module. The multi-channel ultrasound analog front end has a maximum gain of 48 dB and a maximum resolution of 16 bits to achieve precise measurement of small signals. The high-speed acquisition module is built based on FPGA and adopts the JESD204B interface protocol to achieve fast signal acquisition.

[0037] The phased ultrasound acquisition module includes a multi-channel ultrasound analog front end, whose maximum gain can reach 48 dB and the maximum resolution is 16 bits. The high gain can amplify weak ultrasound signals to a detectable level, while the high resolution ensures precise capture of signal details. This configuration enables this technical solution to achieve precise measurement of small signals and improve the sensitivity to micro-damage 2 and structural changes inside the material. In ultrasonic testing, small signals usually contain key information about the internal microstructure and early damage of the material. By precisely measuring these small signals, potential problems can be detected earlier, improving the accuracy and reliability of the detection.

[0038] Preferably, referring to Figure 3 , both the transmitting transducer array 1 and the receiving transducer array 4 include 16 elements arranged linearly. The transmitting transducer array 1 and the receiving transducer array 4 are placed perpendicular or parallel to each other. Ultrasonic coupling agents are coated between the transmitting transducer array 1 and the plate-shaped material under test 3, and between the plate-shaped material under test 3 and the receiving transducer array 4. For example, the plate-shaped material under test 3 can be an aluminum plate.

[0039] Preferably, it further includes a multi-channel power supply module for power supply.

[0040] Based on the same concept, the present invention also provides a phased multi-channel non-linear ultrasonic non-destructive testing method based on phase-reversal excitation. The detection system includes the following steps: Calculate the multi-channel phase-reversal waveform data through the host computer, calculate the excitation timing instructions corresponding to different channels according to the position of the focal point, and send the multi-channel phase-reversal waveform data and timing instructions to the phased high-energy fundamental frequency ultrasonic excitation module; Through the phased high-energy fundamental frequency ultrasonic excitation module, generate an electrical signal of a multi-channel phase-reversal waveform based on the control instructions of the host computer to suppress the fundamental frequency signal and enhance the harmonic amplitude, and perform delayed excitation on different channels based on the timing control instructions for ultrasonic fixed-point focusing, and then perform linear amplification processing on the electrical signal of the multi-channel phase-reversal waveform; Perform filtering at the transmitting end through a multi-channel low-pass analog filter to reduce the influence of harmonic components at the transmitting end; Convert the amplified electrical signal into an ultrasonic signal through the transmitting transducer array 1 and act on the material under test 3; The ultrasonic signal received from the material 3 to be measured is converted into an electrical signal by the receiving transducer array 4; While suppressing the fundamental wave and enhancing the harmonics of the electrical signal converted by the receiving transducer array 4 through a multi-channel dual-bandpass filter, clutter is filtered out to enhance the non-linear effect of the received signal and further improve the signal-to-noise ratio; Through the phased ultrasound acquisition module, the electrical signal fed back by the multi-channel dual-bandpass filter is filtered, amplified, and sampled to be converted into a digital signal, and the digital signal is sent to the host computer; The host computer extracts the information in the time domain - frequency domain - spatial domain from the received digital signal, and calculates the non-linear parameters to mark the non-linear ultrasonic non-destructive testing result of the material 3 to be measured.

[0041] See Figure 2 , which shows the steps of non-destructive testing and evaluation using a phased multi-channel non-linear ultrasonic non-destructive testing system based on phase-reversal excitation in an embodiment. The technical solution of this embodiment can effectively suppress the fundamental frequency signal and enhance the harmonic amplitude by using the phase-reversal waveform, thereby improving the detection ability for micro-damage 2. Compared with the traditional single-channel non-linear ultrasonic non-destructive testing system, it can scan and inspect a certain range, with a shorter detection time and more accurate results. At the same time, the multi-channel design enables the system to detect the material 3 to be measured from multiple angles, further improving the detection resolution. By delaying the excitation of different channels according to the timing control instruction, fixed-point ultrasonic focusing measurement at any position of interest of the material 3 to be measured can be achieved. The multi-channel low-pass analog filter is used for filtering at the transmitting end, which can effectively reduce the influence of harmonic components at the transmitting end, thereby reducing the background noise and improving the signal quality. The multi-channel dual-bandpass filter not only suppresses the fundamental wave signal and enhances the harmonic signal, but also filters out clutter, which can significantly enhance the non-linear effect of the received signal, contribute to more accurately identifying the non-linear characteristics of the material, achieve high-energy phase-reversal waveform excitation, or other high-energy arbitrary waveform excitation, enhance the non-linear effect while reducing the harmonic interference at the excitation end. Through the multi-channel dual-bandpass filter, while suppressing the fundamental wave and enhancing the harmonics, other frequency components of clutter are filtered out, enhancing the non-linear effect of the received signal and further improving the signal-to-noise ratio. Through the above measures, the signal-to-noise ratio of the system has been significantly improved, and useful signals can be detected more clearly even in the presence of noise, which is particularly important for applications in complex environments.

[0042] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, provided that these changes fall within the scope of the claims of the present invention and their equivalent technologies, they still fall within the protection scope of the present invention.

Claims

1. A phased multi-channel non-destructive testing system for nonlinear ultrasonic based on phase inversion excitation, characterized in that, Including: A host computer that generates multi-channel phase-reversed waveform data and configuration control instructions, extracts information in the time domain, frequency domain, and spatial domain from the received digital signals, and calculates non-linear parameters to mark the results of non-destructive testing of non-linear ultrasonic waves of the material to be tested; A phased high-energy fundamental frequency ultrasonic excitation module that generates electrical signals with multi-channel phase-reversed waveforms according to the control instructions of the host computer to suppress the fundamental frequency signal and enhance the harmonic amplitude, and performs delayed excitation on different channels according to the timing control instructions to perform ultrasonic fixed-point focusing, and then performs linear amplification processing on the electrical signals with multi-channel phase-reversed waveforms; A multi-channel low-pass analog filter for filtering at the transmitting end to reduce the influence of harmonic components at the transmitting end; A transmitting transducer array configured to be coupled to the material to be tested through a coupling agent, convert the amplified electrical signal into an ultrasonic signal and act on the material to be tested; A receiving transducer array configured to be coupled to the material to be tested through a coupling agent, and convert the ultrasonic signal received from the material to be tested into an electrical signal; A multi-channel double-bandpass filter that suppresses the fundamental wave and enhances the harmonics of the electrical signal converted by the receiving transducer array while filtering out clutter to enhance the non-linear effect of the received signal and further improve the signal-to-noise ratio; A phased ultrasonic acquisition module that filters, amplifies, and samples the electrical signals fed back by the multi-channel double-bandpass filter according to the control instructions of the host computer to convert them into digital signals, and sends the digital signals to the host computer.

2. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation according to claim 1, wherein The phased high-energy fundamental frequency ultrasonic excitation module includes a multi-channel digital-to-analog converter and a multi-channel linear amplifier. The multi-channel digital-to-analog converter is used to generate phase-reversed waveforms for each channel, and the multi-channel linear amplifier linearly amplifies the electrical signals with multi-channel phase-reversed waveforms; Among them, the excitation of the phase-reversed waveform is calculated by the host computer to obtain the corresponding waveform data according to the waveform to be excited, and sent to the register of the multi-channel digital-to-analog converter. The multi-channel digital-to-analog converter generates the corresponding waveform excitation according to the waveform data in the register. The phase-reversed waveform data of each channel is excited in the following manner: If the initial input signal is , then the first excitation waveforms of all channels are: , The waveform of the second excitation of all channels is as follows: , For the anti-phase signal, the odd-frequency components have a 180-degree phase shift relative to the positive phase, and the even-frequency components have the same phase, thereby suppressing the fundamental frequency component and increasing the second harmonic amplitude.

3. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation according to claim 1, wherein The phased high-energy fundamental frequency ultrasonic excitation module performs ultrasonic fixed-point focusing by obtaining delayed excitation of different channels based on timing control instructions. The delay time of each channel is calculated as follows: , Among them is the distance from the channel to the focus point, is the maximum distance from all channels to the focus point, C is the speed of sound, and the initial input signal is , then the input signal of the channel is: .

4. The phased multi-channel non-destructive testing system based on phase inversion excitation according to claim 1, characterized in that, The host computer calculates the corresponding waveform data according to the waveform to be excited, calculates the excitation timing instructions corresponding to different channels according to the position of the focus point, and then sends the waveform data and timing instructions to the phased high-energy fundamental frequency ultrasonic excitation module.

5. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation according to claim 4, characterized in that, The host computer receives the digital signals sent by the phased ultrasonic acquisition module, superimposes the acquisition results before and after phase flipping, calculates the amplitude spectrum and non-linear parameters of the signals of each receiving channel, compares the non-linear parameters with the relationship between the non-linear parameters and the damage degree of the material to be tested in the standard database, and obtains the damage detection result of the material to be tested; Among them, the non-linear parameters are calculated in the following manner: Solving the propagation formula of waves at different positions of the non-linear wave equation, we can get: Among them, u is the displacement, n is different channels, β is the second-order non-linear parameter, w is the frequency, k is the wave number, and A is the fundamental wave amplitude; The non-linear parameters are calculated using the following formula: where B is the amplitude of the second harmonic.

6. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation according to claim 4, characterized in that, The initial input waveform is a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses, and the frequency is 2.4 MHz. The waveform data including timing can be calculated using the following formula: where A is the amplitude, is the center frequency of the sine wave, is the Hanning window envelope, T is the total time length, is the specific delay time of each channel, where is the distance from the channel to the focus point, is the maximum distance from all channels to the focus point, and C is the speed of sound; Based on the phase inversion theory, the excitation waveform for all channels for the first time is: The excitation waveform for all channels for the second time is: The phased high-energy fundamental frequency ultrasonic excitation module generates a high-energy multi-period sine electrical signal modulated by a Hanning window with 20 pulses with different phases according to the host computer instruction, and performs delayed excitation on different channels according to the timing control instruction to achieve ultrasonic fixed-point focusing, and then performs linear amplification processing on the signal to make the peak-to-peak value of the excitation waveform reach 190 V.

7. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase-reversal excitation according to claim 1, characterized in that The multi-channel dual band-pass filter includes a band-pass filter and a band-stop filter, and filters out clutter while suppressing the fundamental wave of the ultrasonic signal and enhancing the harmonic wave by adjusting the parameters of the filter.

8. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase-reversal excitation according to claim 1, characterized in that, The phased ultrasonic acquisition module includes a multi-channel ultrasonic analog front end and a high-speed acquisition module. The highest gain of the multi-channel ultrasonic analog front end is 48 dB and the highest resolution is 16 bit to achieve accurate measurement of small signals. The high-speed acquisition module is built based on FPGA and uses the JESD204B interface protocol to achieve fast signal acquisition.

9. The phased multi-channel non-linear ultrasonic non-destructive testing system based on phase inversion excitation according to claim 1, characterized in that, Both the transmitting transducer array and the receiving transducer array include 16 elements arranged linearly, and the transmitting transducer array and the receiving transducer array are placed perpendicular or parallel to each other.

10. A phased multi-channel non-destructive testing method based on phase inversion excitation, applied to the testing system described in claims 1 to 9, characterized in that, It includes the following steps: The host computer calculates the multi-channel phase inversion waveform data, calculates the excitation timing instruction corresponding to different channels according to the position of the focal point, and sends the multi-channel phase inversion waveform data and the timing instruction to the phased high-energy fundamental frequency ultrasonic excitation module; The phased high-energy fundamental frequency ultrasonic excitation module generates an electrical signal with a multi-channel phase inversion waveform based on the control instruction of the host computer to suppress the fundamental frequency signal and enhance the harmonic amplitude, and performs delayed excitation on different channels based on the timing control instruction to perform ultrasonic fixed-point focusing, and then performs linear amplification processing on the electrical signal with the multi-channel phase inversion waveform; The transmitting end is filtered by a multi-channel low-pass analog filter to reduce the influence of the harmonic components at the transmitting end; The amplified electrical signal is converted into an ultrasonic signal by the transmitting transducer array and acts on the material to be measured; The ultrasonic signal received from the material to be measured is converted into an electrical signal by the receiving transducer array; The electrical signal converted by the receiving transducer array is subjected to fundamental wave suppression, harmonic enhancement and clutter filtering by the multi-channel dual band-pass filter to enhance the non-linear effect of the received signal and further improve the signal-to-noise ratio; The phased ultrasonic acquisition module filters, amplifies and samples the electrical signal fed back by the multi-channel dual band-pass filter based on the host computer control instruction to convert it into a digital signal, and sends the digital signal to the host computer; The host computer extracts the information in the time domain - frequency domain - space domain from the received digital signal, and calculates the non-linear parameters to mark the non-destructive testing result of the non-linear ultrasonic of the material to be measured.

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