A nonlinear ultrasonic detection method and system for micro-damage in buried pipelines

Abstract

This invention discloses a nonlinear ultrasonic detection method and system for micro-damage in buried pipelines. The method includes: transmitting an ultrasonic excitation signal to the pipeline; receiving the echo signals of the ultrasonic excitation signal through signal receiving probes set at multiple locations on the pipeline surface to form echo signals of multiple channels; receiving the echo signal of each channel through a signal demodulation device and processing the echo signal of each channel; calculating the composite interference response of the echo signals of other channels to the channel under test based on the processing results; estimating the modulation residual nonlinearity rate of the channel under test based on the complex envelope and ideal modulation envelope of the channel under test, and obtaining the pipeline disturbance tensor of the channel under test by combining the integral mirror symmetric distortion of the channel under test; calculating the second gradient of the pipeline disturbance tensor and forming a time-second gradient matrix; when the trace of the time-second gradient matrix exceeds a preset threshold, micro-damage exists at the pipeline location corresponding to the channel under test.

Description

Technical Field

[0001] This invention belongs to the field of pipeline micro-damage detection technology, and more specifically, relates to a nonlinear ultrasonic detection method and system for buried pipeline micro-damage. Background Technology

[0002] Micro-damage detection for buried pipelines is a crucial technical means to ensure the safety of urban infrastructure and improve pipeline service life and efficiency, especially in the fields of oil, natural gas, water utilities, and urban heating, where it has extremely high engineering application value. As buried pipelines operate for extended periods, they are susceptible to micro-damage such as tiny cracks, corrosion spots, and stress concentration areas due to the combined effects of geological deformation, vehicle loads, temperature changes, corrosion, electrochemical interference, and uneven soil conditions. These micro-damages often manifest as extremely subtle structural changes in their early stages, making them difficult to detect using traditional macroscopic inspection methods. However, once they develop, they can lead to serious accidents such as pipe bursts and leaks, thus placing extremely high demands on their early identification and accurate monitoring.

[0003] Current technologies for detecting micro-damage in buried pipelines mainly include acoustic emission detection, leak acoustic wave detection, ultrasonic guided wave detection, electromagnetic detection (such as magnetic leakage detection and eddy current detection), distributed fiber optic sensing (such as DTS and DAS), and methods based on ground / underground radar or microgravity detection.

[0004] However, current detection methods are mostly "post-incident diagnosis" and cannot accurately capture the real-time evolution of damage. Therefore, there is an urgent need for a technical solution that can accurately detect pipeline damage in real time. Summary of the Invention

[0005] To address the above technical problems, this invention proposes a nonlinear ultrasonic detection method for micro-damage in buried pipelines, comprising:

[0006] An ultrasonic excitation signal is emitted into the pipeline, and the echo signal of the ultrasonic excitation signal is received by signal receiving probes set at multiple locations on the pipeline surface, forming echo signals in multiple channels.

[0007] The echo signal of each channel is received by the signal demodulation device, and the echo signal of each channel is processed. Based on the processing results, the composite interference response of the echo signals of other channels to the channel to be detected is calculated.

[0008] Based on the complex envelope and ideal modulation envelope of the channel under test, the modulation residual nonlinearity of the channel under test is estimated, and combined with the integral mirror symmetric distortion of the channel under test, the pipe disturbance tensor of the channel under test is obtained. The second gradient of the pipe disturbance tensor is calculated, and a time-second gradient matrix is ​​formed.

[0009] When the trace of the time-second gradient matrix exceeds a preset threshold, there is micro-damage at the pipe location corresponding to the channel to be detected.

[0010] Further processing of the echo signal for each channel includes:

[0011] The echo signal of each channel is input into two short-time integrators of the signal demodulation device. The two short-time integrators process the echo signal of the same channel simultaneously, and the output of the two short-time integrators is used as the processing result.

[0012] Furthermore, calculating the composite interferometric response of the channel under test to the echo signals from other channels includes:

[0013]

[0014] in, Let N be the composite interference response of the i-th channel at time t, used to describe the superposition of interference from multiple other channels on the i-th channel. N is the number of interference channels, and I... k (t-τ ik ) represents the output of the first short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel, and τ is the input of the echo signal of the k-th interference channel. ik Q is the time required for the ultrasonic excitation signal to propagate from the position of the k-th interference channel to the position of the i-th channel. k (t-τ ik Γ represents the output of the second short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel. ik is the coupling coefficient between the k-th interference channel and the i-th channel, j is a complex unit, and t is time.

[0015] Furthermore, based on the output of the first long-time integrator, the output of the second long-time integrator, the gain drift of the first long-time integrator, the gain drift of the second long-time integrator, the correction of the gate delay error of the first long-time integrator, and the correction of the gate delay error of the second long-time integrator, the integral mirror symmetry distortion is calculated.

[0016] Furthermore, obtaining the pipe disturbance tensor of the channel to be detected includes:

[0017]

[0018] in, Let Re be the pipe disturbance tensor of the i-th channel at time t, where Re is the real part of the complex number.

[0019] Furthermore, obtaining the ideal modulation envelope includes: obtaining the ideal modulation envelope corresponding to the modulation mode according to the selected signal demodulation device.

[0020] Furthermore, after completing the inspection of all channels, the locations of minor damage in the pipeline are displayed.

[0021] This invention also proposes a nonlinear ultrasonic detection system for micro-damage in buried pipelines, comprising:

[0022] The excitation module is used to transmit ultrasonic excitation signals to the pipeline and receive the echo signals of the ultrasonic excitation signals through signal receiving probes set at multiple positions on the pipeline surface, forming echo signals in multiple channels.

[0023] The interferometric analysis module is used to receive the echo signal of each channel through the signal demodulation device, process the echo signal of each channel, and calculate the composite interferometric response of the echo signals of other channels to the channel under test based on the processing results.

[0024] The pipeline disturbance tensor acquisition module is used to estimate the modulation residual nonlinearity of the channel under test based on the complex envelope and ideal modulation envelope of the channel under test, and obtain the pipeline disturbance tensor of the channel under test by combining the integral mirror symmetric distortion of the channel under test, calculate the second gradient of the pipeline disturbance tensor, and form a time-second gradient matrix.

[0025] The detection module is used to detect micro-damage at the pipe location corresponding to the channel to be detected when the trace of the time-second gradient matrix exceeds a preset threshold.

[0026] Further processing of the echo signal for each channel includes:

[0027] The echo signal of each channel is input into two short-time integrators of the signal demodulation device. The two short-time integrators process the echo signal of the same channel simultaneously, and the output of the two short-time integrators is used as the processing result.

[0028] Furthermore, calculating the composite interferometric response of the channel under test to the echo signals from other channels includes:

[0029]

[0030] in, Let N be the composite interference response of the i-th channel at time t, used to describe the superposition of interference from multiple other channels on the i-th channel. N is the number of interference channels, and I... k (t-τ ik ) represents the output of the first short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel, and τ is the input of the echo signal of the k-th interference channel. ik Q is the time required for the ultrasonic excitation signal to propagate from the position of the k-th interference channel to the position of the i-th channel. k (t-τ ikΓ represents the output of the second short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel. ik is the coupling coefficient between the k-th interference channel and the i-th channel, j is a complex unit, and t is time.

[0031] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0032] Through the above technical solutions, this invention can accurately detect micro-damage at various locations of buried pipelines, thereby improving the operation and maintenance efficiency of maintenance personnel and reducing operation and maintenance costs. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention;

[0034] Figure 2 This is a system structure diagram of Embodiment 2 of the present invention. Detailed Implementation

[0035] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0036] The method provided by this invention can be implemented in a terminal environment that may include one or more of the following components: a processor, a storage medium, and a display screen. The storage medium stores at least one instruction, which is loaded and executed by the processor to implement the method described in the following embodiments.

[0037] A processor may include one or more processing cores. The processor uses various interfaces and lines to connect various parts of the terminal, and performs various functions and processes data by running or executing instructions, programs, code sets or instruction sets stored in the storage medium, and by calling data stored in the storage medium.

[0038] Storage media can include random access memory (RAM) or read-only memory (ROM). Storage media can be used to store instructions, programs, code, code sets, or instructions.

[0039] The display screen is used to show the user interface of each application.

[0040] In addition, those skilled in the art will understand that the structure of the terminal described above does not constitute a limitation on the terminal. The terminal may include more or fewer components, or combine certain components, or have different component arrangements. For example, the terminal may also include radio frequency circuits, input units, sensors, audio circuits, power supplies, and other components, which will not be described in detail here.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment proposes a nonlinear ultrasonic detection method for micro-damage in buried pipelines, including:

[0043] Step 101: An ultrasonic excitation signal is emitted into the pipeline, and the echo signal of the ultrasonic excitation signal is received by signal receiving probes set at multiple positions on the pipeline surface to form echo signals in multiple channels.

[0044] Step 102: Receive the echo signal of each channel through the signal demodulation device, process the echo signal of each channel, and calculate the composite interference response of the echo signals of other channels to the channel under test based on the processing results.

[0045] Preferably, the signal demodulation device is a RAM system, which is a state-of-the-art system primarily used for the study of nonlinear acoustic phenomena (SNAP). This system includes modules such as a broadband gated RF amplifier, a unique tracking receiver, a quadrature phase-sensitive detector, two gated integrators, and a multi-frequency mixer. For example, the RAM system is the RAM-5000. However, this embodiment does not limit the signal demodulation device, as long as it can perform functions such as signal synthesis, modulation control, detection and demodulation, integration and amplification, and gate triggering.

[0046] Specifically, the processing of the echo signal for each channel includes:

[0047] The echo signal of each channel is input into two short-time integrators of the signal demodulation device. The two short-time integrators process the echo signal of the same channel simultaneously, and the output of the two short-time integrators is used as the processing result.

[0048] Specifically, the calculation involves determining the composite interference response of the channel to be tested from the echo signals of other channels. This is the spatial composite wave of the i-th channel after interference, modulation, and superposition by surrounding channels on the pipe. The specific calculation methods include:

[0049]

[0050] in, Let N be the composite interference response of the i-th channel at time t, used to describe the superposition of interference from multiple other channels on the i-th channel. N is the number of interference channels, and I... k (t-τ ik ) represents the output of the first short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel, and τ is the input of the echo signal of the k-th interference channel. ik Q is the time required for the ultrasonic excitation signal to propagate from the position of the k-th interference channel to the position of the i-th channel.k (t-τ ik Γ represents the output of the second short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel. ik is the coupling coefficient between the k-th interference channel and the i-th channel, reflecting the intensity of energy influence and phase shift propagating from the k-th interference channel to the i-th channel, where j is a complex number and t is time.

[0051] Preferably, the coupling coefficient Γ between the k-th interference channel and the i-th channel is calculated using the following formula. ik :

[0052]

[0053] Where, d ik f is the distance from the k-th interference channel to the i-th channel. c f is the center frequency of the ultrasonic excitation signal. In the RAM-5000 system, the excitation signal is output from the synthesizer, and the center frequency of the excitation signal is f. c v is the propagation speed of the ultrasonic excitation signal in the pipe, and α is the attenuation factor, which is usually taken as 1-2, such as 1.5.

[0054] Preferably, in this embodiment, after the echo signal enters the phase-sensitive detector in the RAM-5000 system, it is demodulated. After demodulation, it enters the first short-time integrator and the second short-time integrator respectively, and finally outputs I. k (t-τ ik ) and Q k (t-τ ik ).

[0055] Step 103: Based on the complex envelope and ideal modulation envelope of the channel to be detected, estimate the modulation residual nonlinearity of the channel to be detected, and combine it with the integral mirror symmetric distortion of the channel to be detected to obtain the pipe disturbance tensor of the channel to be detected, calculate the second gradient of the pipe disturbance tensor, and form a time-second gradient matrix.

[0056] Preferably, this embodiment identifies whether the ultrasonic excitation signal produces an abnormal response to the modulation envelope of the ultrasonic excitation signal when propagating in the pipeline by modulating the residual nonlinearity, thereby determining whether there are structural anomalies such as micro-damage, cracks, or nonlinear behavior. Specifically, the modulation residual nonlinearity of the channel under test is estimated by the following method:

[0057]

[0058] Among them, SCRE i Let T be the modulation residual nonlinearity of the i-th channel, and T be the integration time window length. Let be the complex envelope of the i-th channel at time t. For time t-Δt i The ideal modulation envelope at time Δt i Let Λ(t) be the envelope response delay of the i-th channel, and let Λ(t) be the Gaussian window for time t.

[0059] Preferably, the purpose of setting the Gaussian window Λ(t) with time t in this embodiment is to: suppress the window edge effect at the beginning and end of the ultrasonic excitation signal; and simulate the characteristics of the excitation intensity gradually being excited and fading over time.

[0060] Specifically, obtaining the ideal modulation envelope includes: obtaining the ideal modulation envelope corresponding to the modulation mode according to the selected signal demodulation device.

[0061] Specifically, the RAM-5000 synthesizer configures the "theoretical envelope" of the excitation signal. The RAM-5000 supports two modulation modes: Combine and Hanning. Combine is equivalent to additive modulation, while Hanning is a special type of multiplicative modulation. If Combine modulation mode is used, then... Ideal envelope constructed for additive modulation:

[0062]

[0063] Where Δf is the center frequency f of the ultrasonic excitation signal. c The frequency difference between the center frequency of the previous ultrasonic excitation signal and the center frequency of the previous signal, A1 is the center frequency f. c The amplitude of the corresponding ultrasonic excitation signal, where A2 is the amplitude of the previous ultrasonic excitation signal.

[0064] If Hanning mode is used, then Ideal envelope constructed for multiplication modulation:

[0065]

[0066] Where A0 is the center frequency f c The amplitude of the corresponding ultrasonic excitation signal.

[0067] Specifically, the integral mirror symmetry distortion is calculated based on the output of the first long-time integrator, the output of the second long-time integrator, the gain drift of the first long-time integrator, the gain drift of the second long-time integrator, the correction of the gate delay error of the first long-time integrator, and the correction of the gate delay error of the second long-time integrator.

[0068] Preferably, this embodiment detects whether there are changes in the back propagation path, asymmetric cracks, time delay anomalies, or wavefront reconstruction errors in the pipeline by comparing the degree of disruption of the mirror symmetry of the outputs of the two integrators in the RAM-5000 system. Specifically, the integral mirror symmetry distortion is calculated in the following way:

[0069]

[0070] Among them, DINSD i Let denot be the integral mirror symmetric distortion of the i-th channel, ρ(t) be the gain drift of the first long-time integrator at time t, S1(t+δ1) be the output of the first long-time integrator at time t+δ1, ζ(t) be the gain drift of the second long-time integrator at time t, S2(T-t+δ2) be the output of the second long-time integrator at time T-T+δ2, δ1 be the correction for the gating delay error of the first long-time integrator, and δ2 be the correction for the gating delay error of the second long-time integrator.

[0071] Preferably, in this embodiment, the gain drift ρ(t) of the first long-time integrator at time t is calculated in the following manner:

[0072] ρ(t) = 1 + ∈1·cos(ω1t + φ1)

[0073] Wherein, ∈1 is the gain swing amplitude of the first long-time integrator (generally 0.01-0.05 (1%-5%)), ω1 is the drift frequency of the first long-time integrator, and φ1 is the phase offset of the first long-time integrator.

[0074] The method for calculating the gain drift ζ(t) of the second long-time integrator at time t is as follows:

[0075] ζ(t)=1+∈2·sin(ω2t+φ2)

[0076] Wherein, ∈2 is the gain swing amplitude of the second long-time integrator (which can also be 0.01-0.05 (1%-5%)), ω2 is the drift frequency of the second long-time integrator, and φ2 is the phase offset of the second long-time integrator.

[0077] Preferably, δ1 is obtained from the integration gating delay parameters of the RAM-5000 system as the correction amount for the gating delay error of the first long-time integrator, and δ2 is obtained as the correction amount for the gating delay error of the second long-time integrator.

[0078] Specifically, obtaining the pipe disturbance tensor of the channel to be tested includes:

[0079]

[0080] in, Let Re be the pipe disturbance tensor of the i-th channel at time t, where Re is the real part of the complex number.

[0081] Step 104: When the trace of the time-second gradient matrix exceeds a preset threshold, there is micro-damage at the pipe location corresponding to the channel to be detected.

[0082] Specifically, after completing the inspection of all channels, the locations of minor damage in the pipeline will be displayed.

[0083] Example 2

[0084] like Figure 2 As shown, this embodiment proposes a nonlinear ultrasonic testing system for micro-damage in buried pipelines, comprising:

[0085] The excitation module is used to transmit ultrasonic excitation signals to the pipeline and receive the echo signals of the ultrasonic excitation signals through signal receiving probes set at multiple positions on the pipeline surface, forming echo signals in multiple channels.

[0086] The interferometric analysis module is used to receive the echo signal of each channel through the signal demodulation device, process the echo signal of each channel, and calculate the composite interferometric response of the echo signals of other channels to the channel under test based on the processing results.

[0087] Specifically, the processing of the echo signal for each channel includes:

[0088] The echo signal of each channel is input into two short-time integrators of the signal demodulation device. The two short-time integrators process the echo signal of the same channel simultaneously, and the output of the two short-time integrators is used as the processing result.

[0089] Specifically, calculating the composite interferometric response of the channel to be tested by the echo signals from other channels includes:

[0090]

[0091] in, Let N be the composite interference response of the i-th channel at time t, used to describe the superposition of interference from multiple other channels on the i-th channel. N is the number of interference channels, and I... k (t-τ ik ) represents the output of the first short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel, and τ is the input of the echo signal of the k-th interference channel. ik Q is the time required for the ultrasonic excitation signal to propagate from the position of the k-th interference channel to the position of the i-th channel. k (t-τ ik Γ represents the output of the second short-time integrator in the signal demodulation device for the echo signal of the k-th interference channel. ikis the coupling coefficient between the k-th interference channel and the i-th channel, j is a complex unit, and t is time.

[0092] Preferably, the coupling coefficient Γ between the k-th interference channel and the i-th channel is calculated using the following formula. ik :

[0093]

[0094] Where, d ik f is the distance from the k-th interference channel to the i-th channel. c denoted as the center frequency of the ultrasonic excitation signal, v as the propagation speed of the ultrasonic excitation signal in the pipe, and α as the attenuation factor, which is usually taken as 1 to 2, such as 1.5.

[0095] The pipeline disturbance tensor acquisition module is used to estimate the modulation residual nonlinearity of the channel under test based on the complex envelope and ideal modulation envelope of the channel under test, and obtain the pipeline disturbance tensor of the channel under test by combining the integral mirror symmetric distortion of the channel under test, calculate the second gradient of the pipeline disturbance tensor, and form a time-second gradient matrix.

[0096] Preferably, the modulation residual nonlinearity of the channel under test is estimated by the following method:

[0097]

[0098] Among them, SCRE i Let T be the modulation residual nonlinearity of the i-th channel, and T be the integration time window length. Let be the complex envelope of the i-th channel at time t. For time t-Δt i The ideal modulation envelope at time Δt i Let Λ(t) be the envelope response delay of the i-th channel, and let Λ(t) be the Gaussian window for time t.

[0099] Specifically, obtaining the ideal modulation envelope includes: obtaining the ideal modulation envelope corresponding to the modulation mode according to the selected signal demodulation device.

[0100] Specifically, the integral mirror symmetry distortion is calculated based on the output of the first long-time integrator, the output of the second long-time integrator, the gain drift of the first long-time integrator, the gain drift of the second long-time integrator, the correction of the gate delay error of the first long-time integrator, and the correction of the gate delay error of the second long-time integrator.

[0101] Preferably, the integral mirror symmetry distortion is calculated in the following way:

[0102]

[0103] Among them, DINSD i Let ρ(t) be the integral mirror symmetry distortion of the i-th channel, ρ(t) be the gain drift of the first long-time integrator at time t, S1(t+δ1) be the output of the first long-time integrator at time t+δ1, ζ(t) be the gain drift of the second long-time integrator at time t, S2(T-t+δ2) be the output of the second long-time integrator at time T-t+δ2, δ be the correction for the gate delay error of the first long-time integrator, and δ2 be the correction for the gate delay error of the second long-time integrator.

[0104] Specifically, obtaining the pipe disturbance tensor of the channel to be tested includes:

[0105]

[0106] in, Let Re be the pipe disturbance tensor of the i-th channel at time t, where Re is the real part of the complex number.

[0107] The detection module is used to detect micro-damage at the pipe location corresponding to the channel to be detected when the trace of the time-second gradient matrix exceeds a preset threshold.

[0108] Specifically, after completing the inspection of all channels, the locations of minor damage in the pipeline will be displayed.

[0109] Example 3

[0110] This invention also proposes a storage medium storing multiple instructions for implementing the aforementioned nonlinear ultrasonic detection method for micro-damage in buried pipelines.

[0111] Optionally, in this embodiment, the storage medium may be located in any computer terminal in a group of computer terminals in a computer network, or in any mobile terminal in a group of mobile terminals.

[0112] Optionally, in this embodiment, the storage medium is configured to store program code for performing the method steps of Embodiment 1.

[0113] Example 4

[0114] This invention also proposes an electronic device, including a processor and a storage medium connected to the processor. The storage medium stores multiple instructions, which can be loaded and executed by the processor to enable the processor to execute the aforementioned nonlinear ultrasonic detection method for micro-damage in buried pipelines.

[0115] Specifically, the electronic device in this embodiment can be a computer terminal, which may include one or more processors and a storage medium.

[0116] The storage medium can be used to store software programs and modules, such as the nonlinear ultrasonic detection method for micro-damage in buried pipelines in this embodiment of the invention. The processor executes the software programs and modules stored in the storage medium to perform various functional applications and data processing, thus realizing the aforementioned nonlinear ultrasonic detection method for micro-damage in buried pipelines. The storage medium may include high-speed random access storage media, and may also include non-volatile storage media, such as one or more magnetic storage systems, flash memory, or other non-volatile solid-state storage media. In some instances, the storage medium may further include storage media remotely configured relative to the processor, which can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0117] The processor can execute the method steps of Embodiment 1 by calling the information and application stored in the storage medium through the transmission system.

[0118] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0119] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0120] In the several embodiments provided by this invention, it should be understood that the disclosed technical content can be implemented in other ways. The system embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, indirect coupling or communication connection between units or modules, and may be electrical or other forms.

[0121] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0122] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0123] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, optical disks, and other media capable of storing program code.

[0124] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for nonlinear ultrasonic testing of microdamage in a buried pipeline, characterized in that, The method comprises the following steps: An ultrasonic excitation signal is emitted to the pipeline, and a signal receiving probe arranged at multiple positions on the surface of the pipeline receives an echo signal of the ultrasonic excitation signal, thereby forming echo signals of multiple channels; The echo signals of each channel are received by a signal demodulation device, and the echo signals of each channel are processed, and according to the processing result, a complex interference response of the echo signals of other channels to a to-be-detected channel is calculated; The processing of the echo signals of each channel comprises the following steps: The echo signals of each channel are input into two short-time integrators of the signal demodulation device, the echo signals of the same channel are processed by the two short-time integrators at the same time, and the outputs of the two short-time integrators are taken as the processing result; The calculation of the complex interference response of the echo signals of other channels to the to-be-detected channel comprises the following steps: ， in, For time Time The composite interference response of the first channel is used to describe the response of the other multiple channels to the first channel. Interference from multiple channels superimposed. The number of interference channels, For the first The echo signals from each interference channel are output from the first short-time integrator in the signal demodulation device. For the ultrasonic excitation signal from the first The position of the interference channel propagates to the first... The time required to locate each channel For the first The echo signal from each interference channel is output by the second short-time integrator in the signal demodulation device. For the first The first interference channel and the first The coupling coefficient of each channel, For complex units, For time; According to the complex envelope of the to-be-detected channel and an ideal modulation envelope, a modulation residual nonlinearity of the to-be-detected channel is estimated, and in combination with an integral mirror symmetry distortion amount of the to-be-detected channel, a pipeline disturbance tensor of the to-be-detected channel is obtained, a second-order gradient of the pipeline disturbance tensor is calculated, and a time-second-order gradient matrix is formed; According to the output of the first long-time integrator, the output of the second long-time integrator, the gain drift amount of the first long-time integrator, the gain drift amount of the second long-time integrator, the correction amount of the gate delay error of the first long-time integrator, and the correction amount of the gate delay error of the second long-time integrator, the integral mirror symmetry distortion amount is calculated; acquiring a pipe disturbance tensor of a channel to be detected comprises; , wherein is time the time channel pipe disturbance tensor, is the real part of a complex number; When the trace of the time-second-order gradient matrix exceeds a preset threshold, it is determined that there is a micro-damage in the pipeline position corresponding to the to-be-detected channel.

2. A method of nonlinear ultrasonic testing for microdamage of a buried pipeline according to claim 1, characterized in that, The ideal modulation envelope is obtained according to a selected modulation mode of the signal demodulation device.

3. A method for nonlinear ultrasonic testing of microdamage in a buried pipeline according to claim 1, characterized in that, After the detection of all channels is completed, the position of the pipeline where the micro-damage exists is displayed.

4. A nonlinear ultrasonic testing system for microdamage in buried pipelines, characterized in that, The method comprises the following steps: An excitation module is configured to emit an ultrasonic excitation signal to the pipeline, and a signal receiving probe arranged at multiple positions on the surface of the pipeline receives an echo signal of the ultrasonic excitation signal, thereby forming echo signals of multiple channels; An interference analysis module is configured to receive the echo signals of each channel by a signal demodulation device, and process the echo signals of each channel, and according to the processing result, calculate a complex interference response of the echo signals of other channels to a to-be-detected channel; The processing of the echo signals of each channel comprises the following steps: The echo signals of each channel are input into two short-time integrators of the signal demodulation device, the echo signals of the same channel are processed by the two short-time integrators at the same time, and the outputs of the two short-time integrators are taken as the processing result; The calculation of the complex interference response of the echo signals of other channels to the to-be-detected channel comprises the following steps: ， in, For time Time The composite interference response of the first channel is used to describe the response of the other multiple channels to the first channel. Interference from multiple channels superimposed. The number of interference channels, For the first The echo signals from each interference channel are output from the first short-time integrator in the signal demodulation device. For the ultrasonic excitation signal from the first The position of the interference channel propagates to the first... The time required to locate each channel For the first The echo signal from each interference channel is output by the second short-time integrator in the signal demodulation device. For the first The first interference channel and the first The coupling coefficient of each channel, For complex units, For time; An obtaining pipeline disturbance tensor module is configured to estimate a modulation residual nonlinearity of the to-be-detected channel according to a complex envelope of the to-be-detected channel and an ideal modulation envelope, and in combination with an integral mirror symmetry distortion amount of the to-be-detected channel, obtain a pipeline disturbance tensor of the to-be-detected channel, calculate a second-order gradient of the pipeline disturbance tensor, and form a time-second-order gradient matrix. The integral mirror symmetry distortion amount is calculated according to the output of the first long-time integrator, the output of the second long-time integrator, the gain drift amount of the first long-time integrator, the gain drift amount of the second long-time integrator, the correction amount of the gated delay error of the first long-time integrator and the correction amount of the gated delay error of the second long-time integrator; acquiring a pipe disturbance tensor of a channel to be detected comprises; , wherein is time the time the pipe disturbance tensor of the is taking the real part of a complex number; The detection module is configured to detect that the pipeline position corresponding to the to-be-detected channel has micro-damage when the trace of the matrix of the time-second-order gradient exceeds a preset threshold.

Images