Flange pipe radial stress measurement method, system, electronic device and storage medium

Abstract

The present application relates to the technical field of stress calculation, in particular to a flange pipeline radial stress measurement method, system, electronic device and storage medium. The method defines a stress tensor to describe the three-dimensional stress of the pipeline, equivalent to an orthogonal anisotropic medium, and establishes a correlation model between the elastic constant and the stress. The ultrasonic guided wave propagation equation is constructed to calculate the dispersion curve and the coupling relationship, and the coupling equation of the multi-axial stress and the phase velocity change is fitted. The hoop mode and the non-dispersive working point sensitive to the radial stress and insensitive to the stress in other directions are screened. The sensor array is deployed to collect signals, and the phase velocity change is extracted after processing. The axial and hoop stresses are solved by step-by-step substitution into the coupling equation, and finally the radial stress is solved. The method considers the superimposed influence of multi-axial stress, realizes accurate measurement of radial stress through mode selection and step-by-step solving, and solves the problem of nonlinear interference.

Description

Technical Field

[0001] This invention relates to the field of stress calculation technology, specifically to a method, system, electronic device, and storage medium for measuring radial stress in flange pipes. Background Technology

[0002] Existing pipeline stress measurement technologies include those based on the acoustoelastic effect. However, this approach treats the medium as transversely isotropic based on acoustoelastic theory, generally only considering axial stress and based on the uniaxial stress assumption. Its model of the relationship between phase velocity change and stress is generally only applicable to stress in a single direction. However, the radial stress of flanged pipelines is not a simple stress in a single direction, but a complex state of superposition of multiaxial stresses. This is because the internal pressure of the medium generates radial stress, the bolt preload generates circumferential and axial stresses on the flange, and the thermal expansion and contraction of the pipeline introduces additional axial stresses, which are coupled with radial stresses.

[0003] Multiaxial stress leads to the nonlinear superposition of the acoustoelastic effect, causing the phase velocity change of the ultrasonic guided wave to no longer be a linear function of a single stress. This results in significant errors when inverting radial stress using existing methods (for example, circumferential stress may mask the acoustoelastic signal of radial stress). Summary of the Invention

[0004] The purpose of this invention is to provide a method, system, electronic device, and storage medium for measuring radial stress in flange pipes, in order to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] Methods for measuring radial stress in flanged pipes, including the following steps:

[0007] Define the stress tensor and represent the three-dimensional stress state of the flange pipe as a second-order tensor matrix; equate the isotropic medium under multiaxial stress to an orthogonal anisotropic medium and establish the relationship between the elastic constant matrix and the stress tensor.

[0008] Establish the propagation equation of ultrasonic guided waves in orthogonal anisotropic media;

[0009] Calculate the dispersion curve and coupling relationship, establish a set of characteristic equations, and solve the phase velocity dispersion curve of the multimode guided wave; generate sample data and fit the coupling equation of multiaxial stress and phase velocity variation;

[0010] Calculate the sensitivity coefficients of different guided wave modes to stress in each direction, screen out circumferential modes with high sensitivity coefficients to radial stress and low sensitivity coefficients to circumferential / axial stress, and select the operating point of the circumferential mode in the non-dispersion frequency band;

[0011] Deploy a sensor array to collect axial stress signals, and collect radial and circumferential stress signals;

[0012] The circumferential array is controlled to emit circumferential modal guided waves, and the axial array is emitted longitudinal modal guided waves. Multiple time-domain signals are acquired synchronously and averaged. Noise is removed, signal envelopes are extracted, and phase velocity changes are calculated.

[0013] Substitute the phase velocity change of the axial array into the coupling equation, fix the radial and circumferential stresses as zero, solve for the axial stress, solve for the circumferential stress, substitute the calculated circumferential and axial stresses into the coupling equation, and solve for the radial stress.

[0014] Furthermore, establishing a set of characteristic equations and solving for the phase velocity dispersion curve of multimode guided waves includes: constructing a three-dimensional model of the pipeline based on cylindrical coordinates, transforming the geometric features of the pipeline into coordinate parameters, decomposing the displacement field of the ultrasonic guided wave into radial, circumferential, and axial components using the separation of variables method, establishing a wave equation including stress correction terms by combining the elastic constant matrix of the orthogonal anisotropic medium, deriving the boundary constraints of the characteristic equation based on the stress boundary conditions and displacement continuity conditions of the inner and outer walls of the pipeline, substituting the elastic constant matrix, wave number vector, and boundary conditions into the wave equation to construct a set of characteristic equations with phase velocity as the unknown, solving the eigenvalues ​​of the characteristic equations using the numerical iteration method to obtain the phase velocities of different modes of guided waves at different frequencies, and generating dispersion curves by plotting the relationship curve between phase velocity and frequency.

[0015] Furthermore, the fitting of the coupling equation between multiaxial stress and phase velocity variation includes: generating multiple sets of sample data using the finite element method, and fitting the coupling equation using a multiple linear regression algorithm.

[0016] ; where k r k θ k z σ represents the sensitivity coefficients of radial, circumferential, and axial stresses to changes in phase velocity, respectively. r For radial stress, σ θ For circumferential stress, σ z Δv represents the axial stress, and Δv is the output variable.

[0017] Furthermore, the sensitivity coefficients of different guided wave modes to stress in each direction are calculated by changing the radial, circumferential, and axial stress components respectively using the controlled variable method, calculating the phase velocity change rate of different guided wave modes, and obtaining the sensitivity coefficients of each mode to stress in the three directions.

[0018] Furthermore, selecting the operating point of the circumferential mode in the non-dispersion frequency band includes: determining the target mode type, performing segmented analysis on the dispersion curve of the target mode, calculating the fluctuation amplitude of the phase velocity in different frequency bands, and selecting the frequency band with the smallest fluctuation amplitude as the candidate non-dispersion frequency band.

[0019] A radial stress measurement system for flanged pipes includes a hardware subsystem and a software subsystem. The hardware subsystem is used for the transmission, reception, signal conditioning, and synchronous acquisition of ultrasonic guided waves. The hardware subsystem includes a sensor array module, a signal transmission and reception module, a data acquisition module, and an industrial computer or embedded controller. The software subsystem is used for signal processing, dispersion analysis, sensitivity coefficient calculation, and stress decoupling. The software subsystem includes:

[0020] The stress model and dispersion analysis module is used to establish an acoustoelastic theoretical model under multiaxial stress and to calculate the guided wave dispersion curve and stress-phase velocity coupling relationship.

[0021] The sensitivity coefficient and modal screening module is used to screen waveguide modes and operating frequency bands that are highly sensitive to radial stress and low sensitive to circumferential / axial stress.

[0022] The signal processing and phase velocity calculation module is used to denoise the acquired time-domain signal, extract features, and calculate the phase velocity change.

[0023] The multiaxial stress decoupling and radial stress calculation module is used to decouple multiaxial stress based on coupling equations and finally calculate radial stress.

[0024] An electronic device includes one or more processors, which execute the above-described method for measuring radial stress in flange pipes by running programs stored in a memory.

[0025] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for measuring radial stress in flange pipes.

[0026] Compared with existing technologies, this invention has the following advantages: This application uses a three-dimensional stress tensor to describe the radial, circumferential, and axial multiaxial stresses of flanged pipes, treating the medium as an orthogonal anisotropic material and establishing a correlation model between elastic constants and stress, rather than considering only stress in a single direction. Through finite element data and multivariate regression, a coupling equation between phase velocity change and stress in the three directions is fitted, quantifying the superposition effect of multiaxial stresses and solving the nonlinear interference problem. The sensitivity coefficients of each guided wave mode to different stresses are calculated, and the circumferential mode (e.g., T(0,1)) that is sensitive to radial stress but insensitive to circumferential / axial stress is selected, along with its non-dispersion frequency band, reducing the masking of radial signals by other stresses. Signals are acquired using axial and circumferential sensor arrays respectively. The axial stress is first calculated, then the circumferential stress is calculated in combination with the axial stress, and finally, the radial stress is obtained by substituting it into the coupling equation, achieving multiaxial stress separation. Attached Figure Description

[0027] Figure 1 This is a flowchart of the radial stress measurement method for flange pipes according to the present invention;

[0028] Figure 2 This is a diagram showing the software subsystem components of the flange pipe radial stress measurement system of the present invention. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This application discloses a method for measuring radial stress in flanged pipes, such as... Figure 1 ,include:

[0031] Step s001: Define the stress tensor and represent the three-dimensional stress state of the flange pipe as a second-order tensor matrix; equate the isotropic medium under multiaxial stress to an orthogonal anisotropic medium and establish the relationship between the elastic constant matrix and the stress tensor.

[0032] Establish the propagation equation of ultrasonic guided waves in orthogonal anisotropic media;

[0033] Step s002: Calculate the dispersion curve and coupling relationship, establish a set of characteristic equations, and solve the phase velocity dispersion curve of the multimode guided wave; generate sample data and fit the coupling equation of multiaxial stress and phase velocity variation;

[0034] Step s003: Calculate the sensitivity coefficients of different guided wave modes to stress in each direction, screen out circumferential modes with high sensitivity coefficients to radial stress and low sensitivity coefficients to circumferential / axial stress, and select the operating point of the circumferential mode in the non-dispersion frequency band;

[0035] Step s004: Deploy the sensor array to collect axial stress signals and radial and circumferential stress signals;

[0036] Step s005: Control the circumferential array to emit circumferential mode guided waves, the axial array to emit longitudinal mode guided waves, synchronously acquire multiple time-domain signals and average them, remove noise, extract the signal envelope, and calculate the phase velocity change.

[0037] Step s006: Substitute the phase velocity change of the axial array into the coupling equation, fix the radial and circumferential stresses as zero, solve for the axial stress, solve for the circumferential stress, substitute the calculated circumferential and axial stresses into the coupling equation, and solve for the radial stress.

[0038] For step s002: calculate the dispersion curve and coupling relationship, establish a set of characteristic equations, and solve the phase velocity dispersion curve of the multimode guided wave. Specifically, in implementation, a three-dimensional model of the pipeline is constructed based on cylindrical coordinates, and the geometric features of the pipeline are transformed into coordinate parameters. The displacement field of the ultrasonic guided wave is decomposed into radial, circumferential, and axial components using the separation of variables method. Combining the elastic constant matrix of the orthogonal anisotropic medium, a wave equation including stress correction terms is established. Based on the stress boundary conditions and displacement continuity conditions of the inner and outer walls of the pipeline, the boundary constraint conditions of the characteristic equation are derived. The elastic constant matrix, wave number vector, and boundary conditions are substituted into the wave equation to construct a set of characteristic equations with phase velocity as the unknown. The eigenvalues ​​of the characteristic equations are solved using the numerical iteration method to obtain the phase velocities of different modes of guided waves at different frequencies. The dispersion curve is generated by plotting the relationship curve between phase velocity and frequency. The solution results are used for mode identification and classification to distinguish different types of guided wave modes such as longitudinal, circumferential, and bending modes. The continuity and stability of the dispersion curve under boundary conditions are verified. The influence of multiaxial stress on the propagation characteristics of guided waves is analyzed by comparing the dispersion curve with that under stress-free conditions.

[0039] For the generated sample data, a coupling equation between multiaxial stress and phase velocity changes is fitted. Specifically, multiple sets of sample data are generated using the finite element method, and the coupling equation is obtained by fitting the data using a multiple linear regression algorithm.

[0040] ; where k r k θ k z σ represents the sensitivity coefficients of radial, circumferential, and axial stresses to changes in phase velocity, respectively. r For radial stress, σ θ For circumferential stress, σ z Let Δv be the axial stress and Δv be the output variable. For step s003: calculate the sensitivity coefficients of different guided wave modes to stress in each direction, screen the circumferential mode with a high sensitivity coefficient to radial stress and a low sensitivity coefficient to circumferential / axial stress, and select the operating point of the circumferential mode in the non-dispersion frequency band; in practice, the radial, circumferential, and axial stress components are changed by controlling the variable method respectively, the phase velocity change rate of different guided wave modes is calculated, the sensitivity coefficients of each mode to stress in the three directions are obtained, a sensitivity coefficient matrix is ​​constructed, and the mode with a significantly higher radial stress sensitivity coefficient than that in the circumferential and axial directions is screened by matrix analysis. Candidate modes with mode transitions or excessively fast attenuation are excluded based on the mode propagation characteristics, the target mode type is determined, the dispersion curve of the target mode is segmented and analyzed, the fluctuation amplitude of phase velocity in different frequency bands is calculated, and the frequency band with the smallest fluctuation amplitude is selected as the candidate non-dispersion frequency band.

[0041] For step s004: Deploy the sensor array to collect axial stress signals, and collect radial and circumferential stress signals; construct the sensor array unit using a modular design concept to ensure good signal synchronization and spatial complementarity among the sensors; achieve tight connection between the sensors and the outer wall of the pipe through a coupling agent; improve the adhesion between the sensors and the pipe surface by using a flexible substrate material; design a special fixture to fix the sensor array to ensure positional stability during measurement; configure a signal conditioning circuit to improve the anti-interference capability of the sensors; use a wireless transmission module to achieve remote connection between the sensor array and the data acquisition system; and construct a multi-channel synchronous acquisition system to achieve parallel acquisition of axial and circumferential stress signals.

[0042] The following is a detailed explanation of a method for measuring radial stress in flanged pipes:

[0043] A method for measuring radial stress in flanged pipes specifically includes: establishing an acoustoelastic theoretical model under multiaxial stress; defining multiaxial stress components; and clarifying the three-dimensional stress state of the flanged pipe, including radial stress σ. r Circumferential stress σ θ axial stress σ z (Including bolt preload and additional stress from thermal expansion and contraction), and based on three-dimensional elasticity, it is converted into a second-order stress tensor matrix:

[0044] ;

[0045] Based on the three-dimensional acoustoelastic theory, an isotropic medium under multiaxial stress is equivalent to an orthotropic medium, and its equivalent elastic constant matrix is:

[0046] C ijkl =C ijkl 0 +D ijklmn σ mn ;

[0047] Among them, C ijkl 0 D is the elastic constant under no stress. ijklmn The sixth-order elastic constant σ is used to describe the coupling relationship between multiaxial stress and elastic modulus. mn These are the stress tensor components.

[0048] A three-dimensional wave equation is established. Based on the dynamic wave equation and the constitutive relation under multiaxial stress, the propagation equation of ultrasonic guided waves in orthogonal anisotropic flange pipes is established: Where σ is the stress tensor under multiaxial stress, ρ is the density of the pipe material, U is the displacement vector, t is the time variable, and "∇" represents the divergence operator, which is used to describe the rate of change of the stress tensor σ in space.

[0049] Calculate the dispersion curve and coupling relationship under multiaxial stress, and establish the multimodal dispersion curve equation:

[0050] In cylindrical coordinates (r, θ, z), the displacement potential of the ultrasonic guided wave is decomposed into radial (r), circumferential (θ), and axial (z) components, and a three-dimensional stress tensor is introduced to correct the elastic constant.

[0051] Based on the geometric parameters of the flanged pipe (pipe outer diameter, wall thickness, flange thickness) and boundary conditions (stress continuity between the pipe inner wall and the medium, displacement continuity at the flange-pipe interface), a set of characteristic equations is established, and the phase velocity dispersion curve equations for different modes (longitudinal, circumferential, and bending modes) under multiaxial stress are obtained by solving them.

[0052] Where ω is the angular frequency, b z denoted as axial wave number, and v as phase velocity.

[0053] Establish a multiaxial stress-phase velocity variation coupled model:

[0054] The phase velocity change Δv is defined as the difference between the phase velocity under multiaxial stress and the phase velocity under stress-free conditions.

[0055] Multiple sets of sample data (σ) were generated using the finite element method. r For radial stress, σ θ For circumferential stress, σ z For axial stress, σ r σ θ σ z (where Δv is the input variable and Δv is the output variable) is used to fit the coupling equation using a multiple linear regression algorithm:

[0056] ; where k r k θ k z These are the sensitivity coefficients of radial, circumferential, and axial stresses to changes in phase velocity, respectively (obtained through calibration using sample data, unit: m / (s・MPa)).

[0057] By screening radial stress-sensitive guided wave modes and frequencies, and based on the dispersion curves from the previous steps, the sensitivity coefficients k of different modes (longitudinal L (0,3), circumferential T (0,1), and bending F (1,2)) under multiaxial stress are calculated. r k θ k z ;

[0058] Selecting the radial stress sensitivity coefficient k r ≥0.8 m / (s·MPa) and circumferential / axial sensitivity coefficient k θ kz The target mode was determined to be the circumferential T (0,1) mode (which has a significant response to radial stress) with a stress ≤0.3 m / (s·MPa).

[0059] For the T(0,1) mode, analyze its phase velocity stability (non-dispersion characteristics) in the target frequency band (e.g., 5kHz-10kHz). Select the frequency corresponding to the horizontal segment of the dispersion curve as 6kHz-8kHz (within this frequency band, the phase velocity fluctuation is ≤2%, and the Δv caused by radial stress is ≥5m / s).

[0060] Construct a multi-directional sensor array by arranging sensors in two directions on straight pipe sections on both sides of the flange (e.g., 50mm-100mm from the flange, avoiding the bolt hole area):

[0061] Axial array: Three sensors are arranged equidistantly along the pipe axis (e.g., 200mm apart), with the transmitter in the middle and the receivers on both sides, to collect axial stress-related signals;

[0062] Circular array: Six sensors are evenly distributed along the circumference of the pipe (e.g., spaced at 60° intervals), one of which is a transmitter and the rest are receivers, used to collect radial and circumferential stress-related signals.

[0063] The sensor uses a piezoelectric ceramic probe, which is tightly attached to the outer wall of the pipe using a coupling agent.

[0064] Under stress-free conditions (pipeline not installed, no medium pressure), the reference signals of each sensor are collected, and the initial value of the phase velocity v0 is recorded; a known uniaxial stress is applied (axial / radial force is applied through a hydraulic device) to verify the consistency of the sensor array's response to stress in each direction.

[0065] The transmitting end of the circumferential array is controlled to transmit a T (0,1) mode guided wave at a fixed frequency (e.g., 7kHz), and the time-domain signals of 6 receiving ends are recorded simultaneously (sampling frequency 1MHz, duration 10ms); the transmitting end of the axial array is controlled to transmit an L (0,3) mode guided wave at a frequency (e.g., 7kHz), and the time-domain signals of 2 receiving ends are recorded simultaneously; each group of signals is sampled 3 times, and the average value is taken to reduce noise interference (signal-to-noise ratio is improved to ≥30dB).

[0066] Environmental noise is removed using a wavelet thresholding denoising algorithm (e.g., using the db6 wavelet basis and decomposing into 5 layers); the signal envelope is extracted using Hilbert transform to determine the waveguide arrival time; the phase velocities v_ring and v_axis of the circumferential / axial array are calculated to obtain the phase velocity change Δv. 环 = v_ring - v0_ring, Δv 轴= v_axis - v0_axis. v0_ring: refers to the initial value of the ultrasonic guided wave phase velocity collected by the circumferential sensor array under stress-free conditions (pipe not installed, no medium pressure), serving as the reference value for the circumferential phase velocity. v_ring: refers to the real-time phase velocity of the ultrasonic guided wave collected by the circumferential sensor array during measurement (under multi-axial stress). Δv 环 : Refers to the change in circumferential phase velocity, i.e., the difference between the real-time phase velocity and the initial reference phase velocity. It reflects the change in the guided wave propagation velocity under circumferential stress and is a key parameter for subsequent substitution into the coupling equations to solve for radial and circumferential stresses. v0_axis: Refers to the initial value of the ultrasonic guided wave phase velocity acquired by the axial sensor array under stress-free conditions, serving as the reference value for the axial phase velocity. v_axis: Refers to the real-time phase velocity of the ultrasonic guided wave acquired by the axial sensor array during measurement. Δv 轴 : refers to the change in axial phase velocity, that is, the difference between the real-time phase velocity and the initial reference phase velocity. It is used to reflect the change in the propagation velocity of the guided wave under axial stress and is the core input parameter for solving axial stress.

[0067] Perform multiaxial stress decoupling and radial stress calculation, and calculate the Δv of the axial array. 轴 Substitute the axial stress-phase velocity relationship (based on the coupling model from the previous steps, with σ fixed). r =0、σ θ =0), solve for the axial stress σ z : ;

[0068] Δv based on a circular array 环 With the already obtained σ z Substituting into the coupling equation, we solve for the circumferential stress σ. θ : ; (where σ r The radial stress, initially estimated, is calculated using the medium pressure formula: σ r = P・d / (2δ), where P is the medium pressure, d is the pipe inner diameter, and δ is the wall thickness.

[0069] σ θ σ z Substituting into the coupling equation, the radial stress σ is solved using the least squares method. r :

[0070] The calculated radial stress is compared with the reference value (measured directly by strain gauges placed at the corresponding positions in the circumferential array), and the error is calculated: if the error is ≤5%, the measurement result is output; if the error is >5%, the previous steps are returned to recalibrate the sensitivity coefficient of the coupled model.

[0071] This application also discloses a radial stress measurement system for flanged pipes. The radial stress measurement system for flanged pipes includes a hardware subsystem and a software subsystem. The hardware subsystem is used for the transmission, reception, signal conditioning and synchronous acquisition of ultrasonic guided waves. The hardware subsystem includes a sensor array module, a signal transmission and reception module, a data acquisition module and an industrial computer or embedded controller. The software subsystem is used to realize signal processing, dispersion analysis, sensitivity coefficient calculation and stress decoupling. Generally, the software subsystem is configured and runs in an industrial computer or embedded controller.

[0072] like Figure 2 The software subsystem includes:

[0073] The stress model and dispersion analysis module 100 is used to establish an acoustoelastic theoretical model under multiaxial stress and to calculate the guided wave dispersion curve and stress-phase velocity coupling relationship.

[0074] Sensitivity coefficient and mode screening module 200 is used to screen guided wave modes and operating frequency bands that are highly sensitive to radial stress and lowly sensitive to circumferential / axial stress.

[0075] The signal processing and phase velocity calculation module 300 is used to denoise the acquired time-domain signal, extract features, and calculate the phase velocity change.

[0076] The multiaxial stress decoupling and radial stress calculation module 400 is used to decouple multiaxial stress based on coupling equations and finally calculate radial stress.

[0077] This application also provides an embodiment of an electronic device. The electronic device is manifested in the form of a general-purpose computing device. The components of the electronic device may include, but are not limited to: one or more processors or processing units, memory, and buses connecting different components (including memory and processing units).

[0078] A bus refers to one or more of several bus architectures, including memory buses or memory controllers, peripheral buses, graphics acceleration ports, processors, or local buses using any of the various bus architectures. Examples of these architectures include, but are not limited to, Industry Standard Architecture (ISA) buses, Micro Channel Architecture (MCA) buses, Enhanced ISA buses, Video Electronics Standards Association (VESA) local buses, and Peripheral Component Interconnect (PCI) buses.

[0079] Electronic devices typically include a variety of computer-readable media. These media can be any available media that can be accessed by the electronic device, including volatile and non-volatile media, and removable and non-removable media.

[0080] The memory may include computer-readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory. Electronic devices may further include other removable / non-removable, volatile / non-volatile computer device storage media. By way of example only, the storage system may be used to read and write non-removable, non-volatile magnetic media.

[0081] The electronic device can also communicate with one or more external devices (e.g., keyboard, pointing device, camera, etc.), may include a display, and may communicate with one or more devices that enable a user to interact with the electronic device, and / or with any device that enables the electronic device to communicate with one or more other computing devices (e.g., network card, modem, etc.). This communication can be performed via an input / output (I / O) interface. Furthermore, the electronic device can also communicate with one or more networks (e.g., Local Area Network (LAN), Wide Area Network (WAN) and / or public networks, such as the Internet) via a network adapter. The network adapter communicates with other modules of the electronic device via a bus. The processor executes various functional applications and data processing by running programs stored in memory, such as implementing the radial stress measurement method for flange pipes provided in the above embodiments of the present invention. This method includes: representing the three-dimensional stress state of the flange pipe as a second-order tensor matrix; equivalentizing the isotropic medium under multiaxial stress to an orthotropic medium, and establishing the relationship between the elastic constant matrix and the stress tensor;

[0082] Establish the propagation equation of ultrasonic guided waves in orthogonal anisotropic media;

[0083] Calculate the dispersion curve and coupling relationship, establish a set of characteristic equations, and solve the phase velocity dispersion curve of the multimode guided wave; generate sample data and fit the coupling equation of multiaxial stress and phase velocity variation;

[0084] Calculate the sensitivity coefficients of different guided wave modes to stress in each direction, screen out circumferential modes with high sensitivity coefficients to radial stress and low sensitivity coefficients to circumferential / axial stress, and select the operating point of the circumferential mode in the non-dispersion frequency band;

[0085] Simultaneously acquire multiple time-domain signals and average them, remove noise, extract the signal envelope, and calculate the phase velocity change.

[0086] Substitute the phase velocity change of the axial array into the coupling equation, fix the radial and circumferential stresses as zero, solve for the axial stress, solve for the circumferential stress, substitute the calculated circumferential and axial stresses into the coupling equation, and solve for the radial stress.

[0087] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the radial stress measurement method for flange pipes provided in the embodiments of the present invention. The method includes: representing the three-dimensional stress state of the flange pipe as a second-order tensor matrix; equating the isotropic medium under multiaxial stress to an orthogonal anisotropic medium, and establishing the relationship between the elastic constant matrix and the stress tensor.

[0088] Establish the propagation equation of ultrasonic guided waves in orthogonal anisotropic media;

[0089] Calculate the dispersion curve and coupling relationship, establish a set of characteristic equations, and solve the phase velocity dispersion curve of the multimode guided wave; generate sample data and fit the coupling equation of multiaxial stress and phase velocity variation;

[0090] Calculate the sensitivity coefficients of different guided wave modes to stress in each direction, screen out circumferential modes with high sensitivity coefficients to radial stress and low sensitivity coefficients to circumferential / axial stress, and select the operating point of the circumferential mode in the non-dispersion frequency band;

[0091] Simultaneously acquire multiple time-domain signals and average them, remove noise, extract the signal envelope, and calculate the phase velocity change;

[0092] Substitute the phase velocity change of the axial array into the coupling equation, fix the radial and circumferential stresses as zero, solve for the axial stress, solve for the circumferential stress, substitute the calculated circumferential and axial stresses into the coupling equation, and solve for the radial stress.

[0093] The computer storage medium of this invention can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, system, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, system, or device.

[0094] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit programs for use by or in conjunction with an instruction execution system, system, or device.

[0095] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0096] The above description is merely one specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring radial stress in flanged pipes, characterized in that, Including the following steps: Define the stress tensor and represent the three-dimensional stress state of the flange pipe as a second-order tensor matrix; equate the isotropic medium under multiaxial stress to an orthogonal anisotropic medium and establish the relationship between the elastic constant matrix and the stress tensor. Establish the propagation equation of ultrasonic guided waves in orthogonal anisotropic media; Calculate the dispersion curve and coupling relationship, establish a set of characteristic equations, and solve the phase velocity dispersion curve of the multimode guided wave. Generate sample data and fit the coupled equation of multiaxial stress and phase velocity variation; Calculate the sensitivity coefficients of different guided wave modes to stress in each direction, screen out circumferential modes with high sensitivity coefficients to radial stress and low sensitivity coefficients to circumferential / axial stress, and select the operating point of the circumferential mode in the non-dispersion frequency band; Deploy a sensor array to collect axial stress signals, and collect radial and circumferential stress signals; The circumferential array is controlled to emit circumferential modal guided waves, and the axial array is emitted longitudinal modal guided waves. Multiple time-domain signals are acquired synchronously and averaged. Noise is removed, signal envelopes are extracted, and phase velocity changes are calculated. Substitute the phase velocity change of the axial array into the coupling equation, fix the radial and circumferential stresses as zero, solve for the axial stress, solve for the circumferential stress, substitute the already calculated circumferential and axial stresses into the coupling equation, and solve for the radial stress. Defining the stress tensor, representing the three-dimensional stress state of a flanged pipe as a second-order tensor matrix includes: clearly defining the three-dimensional stress state of the flanged pipe, including the radial stress σ. r Circumferential stress σ θ axial stress σ z And based on three-dimensional elasticity, it is transformed into a second-order stress tensor matrix: ； To equate an isotropic medium under multiaxial stress to an orthotropic medium, the relationship between the elastic constant matrix and the stress tensor is established as follows: The equivalent elastic constant matrix is: C ijkl =C ijkl 0 +D ijklmn s mn ; Among them, C ijkl 0 D is the elastic constant under no stress. ijklmn σ is a sixth-order elastic constant used to describe the coupling relationship between multiaxial stress and elastic modulus. mn These are the components of the stress tensor; The propagation equation of ultrasonic guided waves in orthogonal anisotropic media is established as follows: Where σ is the stress tensor under multiaxial stress, ρ is the density of the pipe material, U is the displacement vector, t is the time variable, and "∇" represents the divergence operator, which is used to describe the rate of change of the stress tensor σ in space; The calculation of dispersion curves and coupling relationships, the establishment of characteristic equations, and the solution of phase velocity dispersion curves of multimode guided waves include: establishing multimode dispersion curve equations, decomposing the displacement potential of ultrasonic guided waves into radial, circumferential, and axial components in cylindrical coordinates, and introducing a three-dimensional stress tensor to correct the elastic constants. By establishing a set of characteristic equations and solving them, we can obtain the phase velocity dispersion curve equations for different modes under multiaxial stress: Where ω is the angular frequency, b z λ is the axial wave number, and v is the phase velocity; Generate sample data and fit the coupling equation between multiaxial stress and phase velocity change, including: defining the phase velocity change Δv as the difference between the phase velocity under multiaxial stress and the phase velocity in the stress-free state; Multiple sets of sample data were generated using the finite element method, σ r For radial stress, σ θ For circumferential stress, σ z For axial stress, σ r σ θ σ z Let Δv be the input variable and Δv be the output variable. A multiple linear regression algorithm is used to fit the coupled equation: ; where k r k θ k z These are the sensitivity coefficients of radial, circumferential, and axial stresses to changes in phase velocity, respectively.

2. The method for measuring radial stress in flanged pipes according to claim 1, characterized in that, Including the following steps: The process of establishing a set of characteristic equations and solving for the phase velocity dispersion curve of multimode guided waves includes: constructing a three-dimensional model of the pipeline based on cylindrical coordinates, converting the geometric features of the pipeline into coordinate parameters, decomposing the displacement field of the ultrasonic guided wave into radial, circumferential, and axial components using the method of separation of variables, establishing a wave equation including stress correction terms based on the elastic constant matrix of the orthogonal anisotropic medium, deriving the boundary constraints of the characteristic equations based on the stress boundary conditions and displacement continuity conditions of the inner and outer walls of the pipeline, substituting the elastic constant matrix, wave number vector, and boundary conditions into the wave equations to construct a set of characteristic equations with phase velocity as the unknown, solving the eigenvalues ​​of the characteristic equations using a numerical iteration method to obtain the phase velocities of different modes of guided waves at different frequencies, and generating dispersion curves by plotting the relationship between phase velocity and frequency.

3. The method for measuring radial stress in flanged pipes according to claim 1, characterized in that, Including the following steps: The calculation of the sensitivity coefficients of different guided wave modes to stress in each direction includes: changing the radial, circumferential, and axial stress components respectively by controlling the variable method, calculating the phase velocity change rate of different guided wave modes, and obtaining the sensitivity coefficients of each mode to stress in the three directions.

4. The method for measuring radial stress in flanged pipes according to claim 1, characterized in that, Including the following steps: Selecting the operating point of the circumferential mode in the non-dispersion frequency band includes: determining the target mode type, performing segmented analysis on the dispersion curve of the target mode, calculating the fluctuation amplitude of the phase velocity in different frequency bands, and selecting the frequency band with the smallest fluctuation amplitude as the candidate non-dispersion frequency band.

5. A radial stress measurement system for flanged pipes, comprising a hardware subsystem and a software subsystem, characterized in that, The hardware subsystem is used for the transmission, reception, signal conditioning, and synchronous acquisition of ultrasonic guided waves. It includes a sensor array module, a signal transmission and reception module, a data acquisition module, and an industrial computer or embedded controller. The software subsystem is used for signal processing, dispersion analysis, sensitivity coefficient calculation, and stress decoupling. It includes: The stress model and dispersion analysis module is used to establish an acoustoelastic theoretical model under multiaxial stress and to calculate the guided wave dispersion curve and stress-phase velocity coupling relationship. The sensitivity coefficient and modal screening module is used to screen waveguide modes and operating frequency bands that are highly sensitive to radial stress and low sensitive to circumferential / axial stress. The signal processing and phase velocity calculation module is used to denoise the acquired time-domain signal, extract features, and calculate the phase velocity change. The multiaxial stress decoupling and radial stress calculation module is used to decouple multiaxial stress based on coupling equations and finally calculate radial stress.

6. An electronic device comprising one or more processors, characterized in that, The processor executes the radial stress measurement method for flange pipes as described in claims 1-4 by running a program stored in memory.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the radial stress measurement method for flange pipes as described in claims 1-4.

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