Method and equipment for optimizing specification of electromagnetic ultrasonic transducer for detection in pipeline

Abstract

The invention relates to the field of electromagnetic nondestructive testing, in particular to a specification optimization method and equipment of an electromagnetic ultrasonic transducer for internal detection of a pipeline. The method comprises the steps that a detection simulation model is created based on multi-physics field simulation software, then the shapes and specifications of a permanent magnet and a magnet gathering body in the electromagnetic ultrasonic transducer are set, and the magnet gathering body is of a square table type structure; discretizing specification parameters of the to-be-tested pipeline, the permanent magnet and the magnet gathering body to design an orthogonal experiment plan for traversing the search space; analyzing each experiment task by utilizing the detection simulation model to obtain a performance database containing a large number of experiment results; finally, the performance database is used for assisting in completing optimization design of the electromagnetic ultrasonic transducer under the specified working condition. The electromagnetic ultrasonic transducer solves the problem that an existing electromagnetic ultrasonic transducer of a single specification cannot be suitable for nondestructive testing of pipelines of different specifications.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic nondestructive testing, and in particular to a method for optimizing the specifications of an electromagnetic ultrasonic transducer for pipeline inspection, as well as the corresponding data storage medium and equipment for optimizing the specifications of an electromagnetic ultrasonic transducer for pipeline inspection. Background Technology

[0002] Pipelines are widely used in industries such as petroleum, chemical, and power, serving as crucial infrastructure for energy and media transportation. Their operational status directly impacts production safety and equipment reliability. During long-term service, pipelines are frequently subjected to the combined effects of media corrosion, mechanical wear, and cyclic stress, making them prone to defects such as wall thinning and cracks. Failure to detect and assess these defects in a timely manner can lead to serious accidents such as leaks and explosions. Existing research indicates that corrosion-related damage is one of the main causes of pressure pipeline failure, posing a continuous threat to pipeline service life and operational safety. The difficulty of inspection increases significantly, especially under complex operating conditions such as high temperatures and confined spaces. Therefore, conducting efficient and reliable non-destructive testing of in-service pipelines is of great importance for preventing accidents, reducing losses, and achieving pipeline safety management.

[0003] Traditional pipeline non-destructive testing technologies each have their own advantages and disadvantages. Piezoelectric ultrasonic testing has high requirements for surface condition, requiring grinding and the use of coupling agents, which limits its application in high-temperature, coated, or in-service pipelines. Eddy current testing is suitable for near-surface defect monitoring, but its effective thickness measurement range is limited, making it difficult to meet the needs of large-diameter pipeline wall thickness testing. In contrast, the electromagnetic acoustic transducer (EMAT) has significant advantages such as non-contact excitation, no need for coupling medium, and the ability to excite multiple waveforms, exhibiting greater adaptability in complex working conditions and is considered one of the most promising non-destructive pipeline testing technologies.

[0004] Despite the significant advantages of EMAT in complex operating conditions, several limitations remain in its engineering applications. The most prominent bottleneck is its low electromagnetic-to-acoustic conversion efficiency, which directly impacts the energy transmission efficiency of the excitation and reception signals. This results in EMAT-generated ultrasonic amplitudes typically being significantly weaker than traditional piezoelectric ultrasound in actual testing. Common methods to enhance ultrasonic signal intensity include using larger permanent magnets to provide a stronger magnetic field or increasing the pulse excitation power. Studies have shown that with sufficiently high excitation power, ultrasonic signals can be generated in the specimen even without a focusing magnet. However, using larger magnets significantly increases magnetic attraction, reducing the convenience of on-site operation; while increasing pulse power not only leads to increased costs but also increases the dead time of the received signal. Therefore, these methods are not ideal solutions.

[0005] To overcome the aforementioned limitations, scholars both domestically and internationally have conducted extensive research on the structural optimization of electromagnetic acoustic transducers (EMATs) in recent years, proposing various novel design approaches. Sun et al. designed a small permanent magnet structure based on a Halbach array, significantly improving the vertical magnetic flux density and echo signal amplitude without increasing thickness. Wang also proposed an improved MPT using a Halbach magnetic array, increasing the acoustic signal amplitude by approximately 70%, demonstrating the crucial role of magnetic circuit optimization in improving transduction efficiency. Meanwhile, Tu et al. effectively improved the ability to detect small-diameter pipes by developing a small, fully enclosed circular probe and optimizing the PPM design. Miao, combining simulation and experiments, determined the optimal magnet parameters for EMATs, enhancing the sound field focusing effect. Liu improved the sound field distribution by adjusting the tilt angle between the magnet and the coil, maintaining energy uniformity over a wider range. These studies indicate that optimizing the magnet arrangement and coil design has become a major direction for improving EMAT performance. Summary of the Invention

[0006] To address the problem that existing single-specification electromagnetic ultrasonic transducers cannot be applied to non-destructive testing of pipelines of different specifications, this invention provides a specification optimization method for electromagnetic ultrasonic transducers for pipeline internal testing, along with its corresponding data storage medium and equipment.

[0007] The technical solution provided by this invention is as follows: A method for optimizing the specifications of an electromagnetic ultrasonic transducer for pipeline inspection, comprising: S1: Create a detection simulation model based on multiphysics simulation software; it is used to simulate the peak echo signal of a specified electromagnetic ultrasonic transducer in arbitrary pipeline detection.

[0008] S2: The permanent magnet in the electromagnetic ultrasonic transducer is cylindrical, and its specifications include diameter. D m ,high h m The magnet is a frustum with a rectangular cross-section, its upper base fitting against the bottom surface of the permanent magnet; its specifications include the length of the upper base. l 1. The bottom base is long l 2. Top bottom width w 1. Bottom width w 2 and height h s .

[0009] S3: The diameter of the pipe to be tested D p ,thickness t p and permeability μ p As operating parameters; the materials of permanent magnets and concentrating magnets α ,β and specifications D m , h m , l 1. l 2. w 1. w 2. h s Together they serve as equipment parameters.

[0010] S4: Discretize and quantify the theoretical feasible region of the operating parameters and equipment parameters to obtain the experimental feasible region.

[0011] S5: Based on the orthogonal experimental design method, set up an experimental plan that can traverse the feasible experimental domain and satisfy physical constraints; use the detection simulation model to generate the peak echo signal corresponding to each experimental task. A max .

[0012] S6: The associated operating parameters, equipment parameters, and echo signal peak values ​​of each group are used as metadata to form a performance database.

[0013] S7: Preset the suction force constraint, signal quality constraint, and material constraint of the magnet in the current measurement scenario; query several metadata records that meet the constraints from the performance database, and then select the equipment parameters that can achieve the best echo signal peak value from the spare parts library as the optimization result.

[0014] The present invention also includes a data storage medium storing various metadata in a performance database constructed as described above in the specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection.

[0015] The present invention also includes a specification optimization device for an electromagnetic ultrasonic transducer for pipeline inspection, which includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the aforementioned specification optimization method for an electromagnetic ultrasonic transducer for pipeline inspection, and then generates the optimal parameter matching result of the electromagnetic ultrasonic transducer based on the current operating parameters of the pipeline to be tested.

[0016] The beneficial effects of the technical solution provided by this invention are as follows: This invention designs an EMAT probe structure employing a square-shaped magnetizing element and a cylindrical permanent magnet. Using a created detection simulation model, it obtains data on the detection performance of probes with different specifications of permanent and magnetizing elements when inspecting various pipelines. This results in the generation of a performance database containing massive amounts of data. Based on this performance database, this invention can assist users in optimizing the material and size of the permanent and magnetizing elements in the probes of electromagnetic ultrasonic transducers for different detection scenarios. It can also provide data query services for users to select suitable probes in specific scenarios. This fundamentally overcomes the problems of existing single-type electromagnetic non-destructive testing probes being unable to conform to various complex curved surfaces and prone to signal attenuation due to large lift-off values, thus affecting the accuracy of pipeline wall thickness measurement. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the principle of pipe wall thickness measurement based on EMAT.

[0018] Figure 2 This is a schematic diagram of the EMAT-based pipe wall thickness measurement principle after the introduction of a magnet.

[0019] Figure 3 This is a flowchart of the steps in the specification optimization method for an electromagnetic ultrasonic transducer for pipeline inspection provided in Embodiment 1 of the present invention.

[0020] Figure 4 This is a physical image of the square-shaped magnet designed in Embodiment 1 of the present invention.

[0021] Figure 5 This is a comparison chart of the BH curves of the magnetic materials silicon steel and permalloy in the performance test experiment.

[0022] Figure 6 Simulation scene diagrams for each experimental task.

[0023] Figure 7 This is a waveform diagram of the high-frequency pulse signal input into the high-frequency coil inside the probe during the experiment.

[0024] Figure 8 The distribution cloud map of magnetic flux density on the surface of the specimen under different working conditions.

[0025] Figure 9 This is a comparison chart of the first echo intensity of different magnets in the test experiment. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the 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.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] Example 1 Pipeline wall thickness measurement is a key technology for ensuring the safe operation of industries such as petrochemicals and power generation. Traditional piezoelectric ultrasonic technology requires a coupling agent, while electromagnetic ultrasonic transducers (EMAT) offer the advantage of non-contact operation. Specifically, the traditional principle of pipeline wall thickness measurement based on EMAT is as follows: Figure 1 As shown, the EMAT probe consists of a permanent magnet and a receiving coil. During the detection process, the permanent magnet directly contacts the inner wall of the pipe, locally magnetizing it. When the ultrasonic echo returns to the surface of the specimen, the surface particles vibrate at high frequency under mechanical force, inducing an induced current. The receiving coil receives the echo signal from the pipe, thus enabling the measurement of the pipe wall thickness based on the echo signal. However, considering the large base of the permanent magnet and the relatively small curvature of the pipe in most inspection scenarios, there will be a large non-contact area when the two come into contact, resulting in a significant lift-off effect and reduced energy coupling efficiency. Furthermore, an excessively large contact area between the probe and the pipe can also negatively impact the accuracy of the thickness measurement.

[0029] For example, the excitation and reception mechanisms of ultrasound in EMAT mainly involve Lorentz force, magnetostrictive force, and magnetic force. Taking the coupling mechanism based on Lorentz force as an example, according to the Lorentz force mechanism, the main ways to enhance ultrasound energy include increasing eddy current density or increasing the magnetic flux density of the static bias magnetic field. Therefore, such as... Figure 2 As shown, this embodiment introduces a magnetizing structure below the permanent magnet. Its core function is to constrain and concentrate the magnetic flux, allowing it to be more effectively guided to the surface area of ​​the specimen below the coil. This significantly enhances the local bias magnetic field, thereby improving the ultrasonic excitation efficiency. Furthermore, based on the principle of reciprocity, this structure also enhances the response sensitivity of the receiving coil to the echo signal.

[0030] In pipeline inspection, due to space constraints and high sensitivity requirements, the impact of the focusing magnet on transduction efficiency is more significant. The main function of the focusing magnet in an electromagnetic ultrasonic transducer is to concentrate and enhance the bias magnetic field generated by the permanent magnet, thereby improving transduction efficiency and ultrasonic signal strength. Its performance depends on the comprehensive magnetic characteristics at the operating point, including saturation magnetic field strength and high-frequency loss, which are mainly affected by the permeability and conductivity of the material. Simultaneously, the geometry of the focusing magnet directly affects the magnetic flux distribution and energy coupling effect, playing a crucial role in the overall performance of the electromagnetic ultrasonic transducer. Furthermore, the design of the shape and size of the focusing magnet is also limited by the specifications of the pipeline under test and the permanent magnet. Based on these reasons, the specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection provided in this embodiment can, in conjunction with actual application scenarios, synergistically optimize the material, shape, and size specifications of the matching permanent magnet and focusing magnet, thereby achieving an overall improvement in the signal-to-noise ratio and detection performance of the electromagnetic ultrasonic transducer; assisting users in optimizing probe design or selection for specific application scenarios.

[0031] Specifically, such as Figure 3 As shown, the specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection provided in this embodiment includes the following steps: S1: Create a detection simulation model based on multiphysics simulation software; it is used to simulate the peak value of the echo signal received by the electromagnetic ultrasonic transducer when a pipeline of a specified specification is subjected to non-destructive testing using an electromagnetic ultrasonic transducer of a specified specification.

[0032] In this embodiment, the specifications of the permanent magnet and the focusing magnet are selected as variable parameters for analyzing the electromagnetic ultrasonic transducer. During the parameter optimization process, it is necessary to evaluate the detection performance of electromagnetic ultrasonic transducers of different specifications when performing non-destructive testing on pipelines of various specified specifications. Specifically, in practical applications, this embodiment selects the peak value of the echo signal as the evaluation index of the detection performance.

[0033] Considering the need for coordinated optimization of numerous multidimensional parameters in the specifications of permanent magnets and focusing magnets during the optimization process, this embodiment designs a detection simulation model to simulate the detection effect of a specified electromagnetic ultrasonic transducer on a specified pipeline. The process of the electromagnetic ultrasonic transducer detecting the wall thickness of a pipeline involves multiple effects, including electromagnetics and mechanics, encompassing multiphysics coupling analysis of static magnetic fields, eddy current fields, and acoustic fields. Therefore, this embodiment uses multiphysics simulation software to create a fully realistic detection simulation model. Specifically, the detection simulation model used in this embodiment is based on COMSOL Multiphysics. This software is designed based on the finite element method and achieves multiphysics coupling analysis by solving a system of partial differential equations. The analysis scenarios can cover fields such as electromagnetics, fluid mechanics, and structural mechanics, and support user-defined partial differential equation modeling. Of course, in the practical application of this embodiment, the detection simulation model can also be created using other software capable of multiphysics simulation besides COMSOL Multiphysics.

[0034] S2: The permanent magnet in the electromagnetic ultrasonic transducer is cylindrical, and its specifications include diameter. D m ,high h m The magnet is shaped like a frustum with a rectangular cross-section, and the larger upper part of the magnet is attached to the bottom surface of the permanent magnet; its specifications include the length of the upper part. l 1. The bottom base is long l 2. Top bottom width w 1. Bottom width w 2. Height h s .

[0035] In the practical application of this embodiment, the permanent magnet to be optimized is designed to be the most common cylindrical shape. Specifically, for pipes of different specifications, permanent magnets with different diameters and heights can be selected to construct the required probes. The structural parameters of the permanent magnet include the diameter... D m and height h m The two-dimensional parameters are constituted. Correspondingly, in the shape design of the magnet, this embodiment preferably uses the following... Figure 4 The illustrated truncated pyramidal shape refers to a magnet with a rectangular cross-section, where the larger upper base of the magnet is attached to the bottom surface of the permanent magnet. Accordingly, the structural parameters of the truncated pyramidal magnet in this embodiment are mainly determined by the length of the upper base. l 1. The bottom base is long l 2. Top bottom width w 1. Bottom width w 2. Height hs It consists of five dimensions of parameters.

[0036] In the magnet-concentrating structure of this embodiment, the larger upper surface is adjacent to the permanent magnet to fully collect magnetic flux. The inclined sidewalls then gradually guide the magnetic flux to the narrower lower surface region, concentrating the magnetic field and effectively reducing energy loss caused by magnetic leakage. Furthermore, compared to traditional rectangular structures, the square-shaped structure of this embodiment enhances magnetic field strength while avoiding excessive eddy current losses caused by sharp right angles, achieving a balance between high magnetic field strength and low energy loss. Therefore, the square-shaped magnet-concentrating structure is particularly suitable for application in the inspection of small-diameter pipes within confined spaces.

[0037] S3: The diameter of the pipe to be tested D p ,thickness t p and permeability μ p As operating parameters; materials of permanent magnets and focusing magnets in electromagnetic ultrasonic transducers α , β With specifications D m , h m , l 1. l 2. w 1. w 2. h s Together they serve as equipment parameters.

[0038] The optimization process in this embodiment mainly analyzes the performance of electromagnetic ultrasonic transducers of different specifications, composed of permanent magnets and focusing magnets, when measuring pipes of specific specifications. Among these, the properties of the pipe under test that affect the detection performance include the pipe's diameter. D p ,thickness t p and permeability μ p In this embodiment, these are referred to as operating parameters. Specifically, the pipe diameter restricts the size of the permanent magnet and the focusing magnet, while the thickness and permeability of the pipe affect the signal quality, which is primarily influenced by the electromagnetic ultrasonic transducer. Regarding the specifications of the permanent magnet and the focusing magnet, this embodiment mainly considers optimizing the material selection and size design of both; these parameters are collectively referred to as equipment parameters in this embodiment.

[0039] S4: The theoretical feasible region of each parameter in the preset operating condition parameters and equipment parameters is discretized and quantified to obtain the experimental feasible region.

[0040] In this embodiment, the value ranges of the operating parameters and equipment parameters constitute their respective theoretical feasible regions. The optimization problem of the permanent magnet and its specifications in this embodiment is essentially a search for the equipment parameters that maximize the echo signal intensity within a high-dimensional space composed of the theoretical feasible regions of the aforementioned equipment parameters, targeting specific operating parameters. Obviously, this problem cannot be solved analytically directly. Based on the actual needs of practical applications, this embodiment discretizes the theoretical feasible regions of each parameter in the equipment and operating parameters, and converts some non-numerical parameters into corresponding numerical values, thereby reaching the experimental feasible region of each parameter. Then, based on the experimental feasible region, the aforementioned optimization problem is transformed into an iterative optimization problem of each parameter in a high-dimensional discrete space.

[0041] Specifically, the method for generating the experimental feasible region of each parameter in this embodiment includes: Materials for permanent magnets and concentrating magnets α , β These are non-numerical parameters; in this embodiment, the materials of the permanent magnet and the concentrating magnet are considered. α , β Each candidate option in the theoretical feasible region is converted into a unique type code, forming a discrete experimental feasible region composed of these type codes. For example, in this embodiment, unique type codes can be assigned to permanent magnet materials based on their type and composition, such as m1, m2, etc. Similarly, unique type codes can be assigned to polymagnet materials based on their type and composition, such as n1, n2, n3, etc.

[0042] The remaining parameters related to the dimensions of the pipes, permanent magnets, and focusing magnets are all numerical parameters. In this embodiment, the sampling interval for each parameter is preset according to the experimental accuracy. D p , t p , μ p , D m , h m , l 1. l 2. w 1. w 2. h s Discrete sampling is performed on the theoretical feasible region to obtain the experimental feasible region for each parameter.

[0043] In practical applications, the experimental feasible region of each parameter can be discretized at equal intervals during the discretization process. For example, the diameter and height of a permanent magnet can be equally divided at intervals of 1-3 mm. Alternatively, the experimental feasible region of certain parameters can be non-uniformly divided based on practical considerations. Typically, for the diameter of the pipe to be tested, a non-uniform division can be made based on the pipe diameter specified in relevant standards, and some non-standard diameter options can be added to enrich the database. For example, assuming the theoretical feasible region of the pipe diameter is 0.1-5m, this embodiment can equally divide the 0.1-1m interval at 0.1m intervals, while for the 1-5m interval, it can be equally divided at 0.3-0.5m intervals.

[0044] S5: An experimental plan based on orthogonal experimental design is established to traverse the feasible experimental domain and satisfy physical constraints for all operating and equipment parameters. Each experimental task in the plan is executed using a transducer detection simulation model, thereby obtaining the peak echo signal achievable by electromagnetic ultrasonic transducers with various equipment parameters under different operating conditions. A max .

[0045] In the simulation process of this embodiment, combining one value of each parameter within its respective experimental feasible region constitutes an experimental task to be tested. Therefore, the total number of experimental tasks corresponding to the search space composed of the above multiple parameters is still very large. To address this issue, in the actual simulation experimental group obtained in this embodiment, considering that the operating parameters and equipment parameters need to satisfy some physical constraints (such as the probe size cannot be larger than the inner diameter of the pipe), and that the equipment parameters also need to satisfy some coupling constraints (such as the size of the magnet should not be larger than the size of the permanent magnet), the high-dimensional discrete space corresponding to the experimental feasible regions of all operating parameters and equipment parameters can be reduced. This reduces the number of experimental tasks to be tested included in the experimental plan.

[0046] Specifically, in practical applications, the physical constraints set refer to the coupling constraints that the relative dimensions of the permanent magnet and the cohesive magnet must satisfy in various equipment parameters under specified operating conditions; these include the geometric constraints of the permanent magnet and the cohesive magnet. Specifically, for the permanent magnet, firstly, the lower limit of the permanent magnet diameter obtained from flux matching is: Pipe constraints arise from the curvature of the pipe's inner wall; when the pipe's inner wall radius is... D p At that time, the circumferential contact width is equal to w 2. The additional lift-off distance at this point h air for: ; Through Lagrange expansion, we can approximate the following in engineering: ; To ensure signal strength, this lift-off distance is set to not exceed the maximum lift-off distance. In this embodiment =1mm, that is: ; That is, it is necessary to ensure w The range of 2 is: ; When a transducer moves within a pipe, the ratio of its outer diameter to the pipe diameter should not be too large; otherwise, blockage can easily occur if the pipe has ellipticity, weld reinforcement, or severe local scaling. Let the transducer diameter... D m Approximately based on pipe diameter D p The decision can then be made by introducing an empirical coefficient. k D (In this embodiment, the value is 0.4–0.6): ; For example, when it is necessary to explicitly specify the safety margin, it can be written as: ; This constraint reflects the fit between the transducer's lateral dimensions and the pipe's inner diameter, ensuring passability within pipe roundness deviations and bends. Finally, the upper limit of the permanent magnet's height is obtained from the probe's total height and bending performance.

[0047] When the transducer is installed in the pipeline, its total height should be less than the pipeline radius to avoid interference when passing through bends or local protrusions such as welds. Therefore: ; Therefore, the upper limit of the permanent magnet height is given as: ; This geometric relationship ensures that the transducer can still pass smoothly within the pipe section with the minimum bending radius, and will not get stuck inside the pipe due to excessive longitudinal dimensions.

[0048] For a concentrator, when guiding a fixed magnetic flux Φ from a permanent magnet to the concentrator, in order to keep the magnetic flux Φ constant, the area must be reduced, and the magnetic field strength must be increased. This is necessary to achieve magnetic field concentration and enhancement, which requires the following: ; In summary, in this embodiment, the geometric constraints of the permanent magnet are: ; The geometric constraints of the magnet are: ; After designing an experimental plan containing numerous experimental tasks, this embodiment only requires inputting the values ​​of the operating parameters and equipment parameters from these experimental tasks into the created detection simulation model to obtain the corresponding echo signal peak values. This embodiment records the corresponding data after each experimental task is completed.

[0049] S6: The associated operating parameters, equipment parameters, and echo signal peak values ​​of each group are used as metadata to form a performance database.

[0050] This step organizes the data from the various experimental tasks recorded in the previous step, resulting in a performance database. In practical applications, the data format of each metadata entry in the performance database is as follows: { D p , t p , μ p}|{ α , D m , h m}|{ β , l 1. l 2. w 1. w 2. h s}→ A max ; In the above formula, "{·}" represents a feature vector composed of multiple feature values; "|" represents feature concatenation; and "→" represents data mapping.

[0051] Using the data in this performance database, users can query the peak echo signal that can be achieved under specific operating conditions and equipment parameters. They can also query the range of values ​​for each equipment parameter that will make the peak echo signal higher than a preset value, given the operating conditions and some equipment parameters.

[0052] S7: Preset the suction force constraint, signal quality constraint, and material constraint of the magnet in the current measurement scenario; query several metadata records that meet the constraints from the performance database, and then select the equipment parameters that can achieve the best echo signal peak value from the spare parts library as the optimization result.

[0053] For example, in practical applications, based on the performance database obtained in the previous steps, this specification provides a new strategy for designing probes that meet requirements under specific working conditions. First, based on the working parameters and measurement requirements of the current scenario, pre-determine the required suction force constraints, signal quality constraints, and material constraints of the magnet to narrow the search range, and then filter out several candidate options from the performance database. Next, based on the available combinations of permanent magnets and magnets in the spare parts library, a second round of filtering is performed on the aforementioned candidate options. Finally, the option with the largest echo signal peak value is selected as the final optimized result from the results of the two rounds of filtering.

[0054] Specifically, in this embodiment, the magnetic attraction of the electromagnetic ultrasonic transducer to the pipe is determined by the contact area between the lower part of the magnet and the pipe; to ensure that the probe moves smoothly inside the pipe without obstruction, the magnetic attraction to the pipe should be less than the theoretical maximum magnetic attraction. F max (This can be calculated based on actual engineering conditions). Therefore, in this embodiment, the preset suction constraint of the transducer is expressed as: ; In the above formula, Indicates the permeability of free space; F max This represents the theoretical maximum suction force.

[0055] Accordingly, the analysis process for signal quality constraints is as follows: To ensure that the excitation ultrasonic signal satisfies the requirement of a magnetic field strength on the specimen surface. B t It should not be less than its preset minimum threshold. B min That is, satisfying: ; The magnetic path during the detection process consists of the following components connected in series: a permanent magnet, a focusing magnet, a pipe-focusing magnet air gap, and the pipe body. Among these, the magnetic reluctance of the permanent magnet... R m for: ; In the above formula, This represents the relative permeability of a permanent magnet; A m This represents the base area of ​​the permanent magnet.

[0056] magnetic resistance of a magnet R s for: ; In the above formula, This indicates the relative permeability of the magnet. Aavg Indicates the waist area of ​​the magnet: ; In the above formula, A1 and A2 are the areas of the upper and lower bases of the magnet, respectively.

[0057] The magnetic reluctance R of the air gap g for: ; Magnetic resistance of the pipe under test R p for: ; In the above formula, Indicates the relative permeability of the pipe; t p Indicates pipe thickness; The magnetic flux provided by the permanent magnet itself Size: ; The magnetic field strength on the surface of the specimen B t The following conditions must be met: ; In summary, the signal quality constraints of the transducer are expressed as follows: ; In the above formula, B m Indicates the remanence of a permanent magnet; R m Indicates the magnetic reluctance of a permanent magnet; R s Indicates the magnetic reluctance of a magnet; R g Indicates the magnetic reluctance of the air gap; R p Indicates the magnetic reluctance of the pipe under test; This represents the minimum threshold of the magnetic field strength on the specimen surface required to obtain a usable echo signal; Indicates the permeability of a permanent magnet; A m This represents the base area of ​​the permanent magnet; Indicates the permeability of a magnet. h air Indicates the distance to lift off; A avg This represents the waist area of ​​the magnet; A 1 represents the area of ​​the top surface of the magnet.

[0058] When selecting a magnet material, its saturation magnetic field density should be ensured. Bsat Greater than B t This ensures that the magnetic field energy of the permanent magnet is fully utilized. Simultaneously, the permeability of the magnet material significantly affects the magnetic reluctance; when its structural height decreases, it is necessary to prevent premature saturation, but high permeability alloys have poor machinability. Furthermore, the material compatibility of the magnet material with pipe wear must be considered. In summary, in this embodiment, the expression for the material constraints of the magnet is: B sat > B t .

[0059] Example 2 To enable a more efficient application of the scheme in Example 1, this embodiment further provides a data storage medium that stores various metadata in the performance database constructed in the specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection as described in Example 1.

[0060] In practical applications, this embodiment can use the data in the performance database itself as a product, or provide data query or search services based on the database to help users optimize the specifications of permanent magnets and focusing magnets in the probe.

[0061] Furthermore, this embodiment also provides a specification optimization device for electromagnetic ultrasonic transducers for pipeline inspection, which includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection as described above, and then generates the optimal parameter matching result of the electromagnetic ultrasonic transducer based on the current operating parameters of the pipeline to be tested.

[0062] Test Experiment

[0063] To verify the performance of the square-shaped magnet and cylindrical permanent magnet probes provided in this embodiment, and the effectiveness of the aforementioned specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection, technicians created the aforementioned detection simulation model and tested the relevant schemes. Part of the experimental content is as follows: 1. Concentrated magnet materials This experiment first uses a performance simulation model to test the influence of the magnetizing material on the probe performance. The choice of magnetizing material directly determines the enhancement effect of the bias magnetic field. Iron, nickel, cobalt, and their alloys typically have high magnetic permeability, which can effectively focus and concentrate the magnetic field. This experiment selects two typical soft magnetic materials, silicon steel (30P120) and permalloy (1J85), and compares and analyzes their application characteristics in electromagnetic ultrasonic transducers.

[0064] Get as Figure 5 The comparison of the BH curves of the two materials shown reveals that permalloy exhibits a steeper initial slope in its BH curve, enabling rapid magnetization even in extremely weak magnetic fields, demonstrating its excellent high permeability. However, its relatively low saturation magnetic field strength limits its application in strong magnetic field conditions. In contrast, silicon steel has weaker magnetization in low magnetic field regions but maintains a stable upward trend over a wider range of magnetic fields, ultimately reaching a higher saturation magnetic field strength, thus possessing stronger magnetic field carrying capacity and anti-saturation performance.

[0065] In summary, both materials have their advantages in magnetic and electrical properties. Permalloy is suitable for weak magnetic fields and high-frequency conditions, while silicon steel exhibits better resistance to saturation under strong magnetic fields. In the optimized design of electromagnetic ultrasonic transducers, material selection needs to be balanced by considering the comprehensive requirements of the detection environment regarding magnetic field strength, frequency response, and energy utilization efficiency.

[0066] 2. Experiment Task Setting

[0067] To accurately simulate the working process of an electromagnetic ultrasonic transducer, a multi-physics coupled finite element model was established, encompassing static magnetic field, eddy current field, and acoustic field, and corresponding boundary conditions were set. The simulation scenario is as follows: Figure 6 As shown, it mainly consists of a permanent magnet, a high-frequency coil, a magnetizing body, and the test piece.

[0068] In each experimental task, a high-frequency pulsed current, as shown in Figure 7, is applied to the high-frequency coil. The signal waveform uses a 3-cycle modulated positive selection pulse, with a concentrated spectrum, facilitating the excitation of a single dominant frequency ultrasonic wave. The pulse center frequency is 5MHz, consistent with the experimental conditions. This high-frequency pulsed current generates a dynamic magnetic field around the conductor and induces eddy currents on the surface of the steel plate. These eddy currents are then excited by the Lorentz force under the action of a static bias magnetic field. The surrounding air region is set as a magnetically insulated boundary to avoid interference from external magnetic fields, and the steel plate boundary is defined as a free boundary in the acoustic field. The model employs a sequential coupling method: first, the static magnetic field distribution is solved; then, a time-varying current is applied to calculate the eddy currents and dynamic magnetic field; finally, the Lorentz force volume force field is imported into the structural mechanics module to solve for the acoustic field.

[0069] To ensure computational accuracy, local mesh refinement was applied to key areas such as the magnet, excitation coil, and steel plate surface. Particularly within the skin depth range of the steel plate, the mesh size was refined to less than 1 / 5 of the skin depth to accurately capture high-frequency eddy current distribution. The overall model element count is approximately 6.7 × 10⁴, achieving a balance between computational accuracy and efficiency.

[0070] 3. Experimental Environment and Simulation Conditions

[0071] In this embodiment, a detection simulation model of electromagnetic-acoustic multiphysics coupling is established using COMSOL Multiphysics. This model can cover the static magnetic field, eddy current field, and acoustic field, and is solved using sequential coupling. The model undergoes local mesh refinement in the areas of the magnet, coil, and specimen surface, with an overall element count of approximately 6.7 × 10⁻⁶. 4 .

[0072] The permanent magnet is cylindrical, and its specifications include diameter. D m With height h m The magnet is a frustum with a rectangular cross-section, and its larger upper base fits against the bottom surface of the permanent magnet. Its specifications are as follows: l 1. l 2. w 1. w 2. h s In this experiment, to control variables and match the small space detection structure, the lengths of the top and bottom of the magnet were fixed at 10 mm, and l1=l2=10 mm were taken.

[0073] Operating parameters: { D p , t p , μ p}

[0074] Equipment parameters: Permanent magnet material α Concentrated magnet materials β and{ D m , h m , l 1 , l 2 , w 1 , w 2 , h s}

[0075] In this embodiment, the following specific parameters are used: the permanent magnet material is N52 neodymium iron boron, and the remanence is B. r =1.44 T; Specification is D m =15 mm, h m =10 mm. The diameter of the copper wire in the coil is 0.2 mm, the number of turns is 15, and the turn spacing is 0.2 mm; the lift-off height h air =0.5 mm; the excitation signal uses, for example Figure 7The three-cycle modulated sinusoidal pulse shown has a center frequency of 5 MHz; the test piece is made of carbon steel plate, with dimensions of 40 mm × 10 mm, and the target thickness for thickness measurement is 25 mm (for subsequent error verification).

[0076] Material parameter discretization: The magnet material β is selected from two types: silicon steel (30P120) and permalloy (1J85). Geometric parameter discretization: A three-factor, four-level experimental feasible region is constructed: w1∈{14,12,10,8} mm; w2∈{7,6,5,4} mm; h s ∈{7,5,3,1} mm.

[0077] 4. Experimental Results and Analysis

[0078] A three-factor, four-level orthogonal experimental design was used to generate 16 sets of experimental tasks with different parameter combinations. Simulations were performed on both silicon steel and permalloy materials for each task, and the peak echo signal was extracted as... A max .

[0079] The following typical results were obtained by summarizing these implementation methods: (1) When the parameter combination is ( w 1 = 8 mm, w 2 = 4 mm, h s When the diameter is 3 mm, the echo peak value of the silicon steel magnet is... A max =2.68 mV, peak echo value of permalloy magnet A max =2.04 mV; (2) When the parameter combination is ( w 1 = 14 mm, w 2 = 7 mm, h s When the diameter is 7 mm, the echo peak value of the silicon steel magnet is... A max =1.59 mV, peak echo value of permalloy magnet A max =0.96 mV.

[0080] Range analysis of the echo peak values ​​reveals that the influence of the three factors, ranked as follows: height h s The largest, followed by the bottom width. w 2. Next, the width of the top base. w 1, that is: h s > w2> w1; The operating parameters, equipment parameters, and echo peak values ​​corresponding to each experimental task are written into the performance database. Except... A max In addition, the index field used for constraint screening is preferably stored synchronously: magnetic field strength on the specimen surface. B t With magnetic attraction F .

[0081] In this embodiment, the following constraints are preset and database retrieval filtering is performed: (1) Suction constraint: To ensure the probe can be easily lifted and moved, a preset maximum allowable suction threshold F is provided. max =40 N. Screening requirements: F ≤ F max ; (2) Signal quality constraints: To ensure that the echo can be used for thickness measurement, a minimum magnetic field threshold B is preset on the specimen surface. min =0.45 T, screening requirements: B t ≥ B min ; (3) Material constraints: To avoid magnet saturation leading to the failure of the magnetizing effect, saturation constraint is adopted: B sat > B t ; In a typical scheme, the saturation magnetic field strength of silicon steel can be taken as approximately B. sat ≈1.8 2.0 T, permalloy approximately B sat ≈1.0 1.2 T.

[0082] Under the above constraints, after obtaining candidate combinations from the performance database and performing secondary screening using the spare parts library, the optimal combination output is: w 1 = 8 mm, 42 = 4 mm h s =3 mm, l 1= l 2 = 10 mm, β =Silicon steel (30P120).

[0083] To verify the effectiveness of the above optimal combination, magnet samples with optimal (8-4-3) and worst (14-7-7) dimensions were prepared in the experiment using silicon steel and permalloy materials, and tested under the same permanent magnet and coil conditions.

[0084] (1) Magnetic field strength B on the surface of the specimen t test: Tested at the center point of the specimen surface (directly below the magnet), no magnet was found: B t =566 mT; Silicon steel 14-7-7: B t =443 mT; Silicon steel 8-4-3: B t =650 mT; Permalloy 14-7-7: B t =243 mT; Permalloy 8-4-3: B t =370 mT.

[0085] (2) Magnetic attraction force F test: The test results showed that: non-magnetic material: F=76 N; silicon steel 14-7-7: F=39.2 N; silicon steel 8-4-3: F=30.1 N; permalloy 14-7-7: F=16.8 N; permalloy 8-4-3: F=15.3 N.

[0086] (3) Echo signal and thickness measurement error: A-scan signals were acquired, and the first and second echoes and signal-to-noise ratio (SNR) were extracted. The thickness was then calculated. For the non-magnetic material: first echo amplitude was 44, second echo amplitude was 31, SNR was 18.97 dB, calculated thickness was 24.81 mm (actual thickness 25 mm), with a relative error of 0.77%. For silicon steel 8-4-3: first echo amplitude was 59, second echo amplitude was 34, SNR was 22.2 dB, calculated thickness was 24.97 mm (actual thickness 25 mm), with a relative error of 0.13%. For permalloy 14-7-7: first echo amplitude was 23, second echo amplitude was 13, SNR was 15.07 dB, calculated thickness was 25.18 mm (actual thickness 25 mm), with a relative error of 0.71%. Based on the above experimental data, the following plots were created: Figure 8 The magnetic flux density distribution cloud map shown, and as shown in the figure Figure 9 The diagram shows a comparison of the first echo intensity of different magnets. The data in the diagram demonstrates that the optimized solution developed in this invention indeed achieves the best performance.

[0087] The above-described embodiments are merely one implementation of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for optimizing the specifications of an electromagnetic ultrasonic transducer for pipeline inspection, characterized in that, It includes: S1: Create a detection simulation model based on multiphysics simulation software; it is used to simulate the peak echo signal of a specified electromagnetic ultrasonic transducer in arbitrary pipeline detection. S2: The permanent magnet in the electromagnetic ultrasonic transducer is cylindrical, and its specifications include diameter. D m ,high h m The magnet is a frustum with a rectangular cross-section, and its upper bottom is in contact with the bottom surface of the permanent magnet. Its specifications include the length of the upper base. l 1. The bottom base is long l 2. Top bottom width w 1. Bottom width w 2 and height h s ; S3: The diameter of the pipe to be tested D p ,thickness t p and permeability μ p As operating parameters; the materials of permanent magnets and concentrating magnets α , β and specifications D m , h m , l 1. l 2. w 1. w 2. h s Together they serve as equipment parameters; S4: Discretize and quantify the theoretical feasible region of the operating condition parameters and equipment parameters to obtain the experimental feasible region; S5: Based on the orthogonal experimental design method, set up an experimental plan that can traverse the feasible domain and satisfy physical constraints; The peak echo signal value for each experimental task was generated using a detection simulation model. A max ; S6: Use the associated operating parameters, equipment parameters and echo signal peak values ​​of each group as metadata to form a performance database; S7: Preset the suction force constraint, signal quality constraint, and material constraint of the magnet in the current measurement scenario; query several metadata records that meet the constraints from the performance database, and then select the equipment parameters that can achieve the best echo signal peak value from the spare parts library as the optimization result.

2. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 1, characterized in that: In step S1, the multiphysics simulation software used is COMSOL Multiphysics.

3. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 1, characterized in that: In step S4, the methods for generating the experimental feasible region for each parameter include: Materials of permanent magnets and concentrating magnets α , β Each candidate in the theoretical feasible region is converted into a dedicated type code, and the resulting discrete experimental feasible region is composed of these type codes. The sampling interval for each parameter is preset according to the experimental accuracy. D p , t p , μ p , D m , h m , l 1. l 2. w 1. w 2. h s Discrete sampling is performed on the theoretical feasible region to obtain the experimental feasible region for each parameter.

4. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 1, characterized in that: In step S5, the physical constraint refers to the coupling constraint that the relative dimensions of the permanent magnet and the cohesive magnet need to satisfy in each equipment parameter under specified operating conditions; including the geometric constraints of the permanent magnet and the geometric constraints of the cohesive magnet. The geometric constraints of the permanent magnet are: ； The geometric constraints of the magnet are: ； In the above formula, k D This represents an empirical coefficient set to reserve a safety margin; k D ∈[0.4,0.6]; h air-max This indicates the preset maximum lift-off distance.

5. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 1, characterized in that: In step S6, the data format for each metadata element is as follows: { D p 、 t p 、 μ p}|{ α 、 D m 、 h m}|{ β 、 l 1、 l 2、 w 1、 w 2、 h s}→ A max ； In the above formula, "{·}" represents a feature vector composed of multiple feature values; "|" represents feature concatenation; and "→" represents data mapping.

6. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 4, characterized in that: In step S7, the suction constraint of the transducer is expressed as: ； In the above formula, B t Indicates the magnetic field strength on the surface of the specimen; Indicates the permeability of free space; F max This represents the theoretical maximum suction force.

7. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 6, characterized in that: In step S7, the signal quality constraint of the transducer is expressed as: ； In the above formula, B m Indicates the remanence of a permanent magnet; R m Indicates the magnetic reluctance of a permanent magnet; R s Indicates the magnetic reluctance of a magnet; R g Indicates the magnetic reluctance of the air gap; R p Indicates the magnetic reluctance of the pipe under test; This represents the minimum threshold of the magnetic field strength on the specimen surface required to obtain a usable echo signal; Indicates the permeability of a permanent magnet; A m This represents the base area of ​​the permanent magnet; Indicates the permeability of a magnet. h air Indicates the distance to lift off; A avg This represents the waist area of ​​the magnet; A 1 represents the area of ​​the top surface of the magnet.

8. The specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection according to claim 7, characterized in that: In step S7, the expression for the material constraint of the magnet is: B sat ＞ B t ； In the above formula, B sat This indicates the saturation magnetic field density of the magnet.

9. A data storage medium, characterized in that: It internally stores various metadata from the performance database constructed in the specification optimization method for electromagnetic ultrasonic transducers for pipeline inspection as described in any one of claims 1-8.

10. A specification optimization device for an electromagnetic ultrasonic transducer for pipeline inspection, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, it implements the specification optimization method for an electromagnetic ultrasonic transducer for pipeline inspection as described in any one of claims 1-8, and then generates the optimal parameter matching result of the electromagnetic ultrasonic transducer based on the current operating parameters of the pipeline under test.

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