A fast calculation method, device and storage device for arbitrary defect leakage magnetic field

Abstract

The present invention discloses a method, device, and storage device for rapidly calculating the leakage magnetic field of an arbitrary defect. The method comprises: establishing a detection model based on an actual detection system, wherein the model includes a magnetizer, an object to be detected, and a detection magnetic field sensor, wherein the object to be detected includes defects of arbitrary shapes; meshing the object to be detected to obtain a series of unit bodies of the meshed object to be detected; setting magnetization parameters of the magnetizer based on the detection model; calculating the magnetic charge density values ​​at all nodes of the series of unit bodies of the object to be detected based on the detection model and the magnetizer parameters; and calculating the leakage magnetic field of the detection area of ​​the object to be detected based on the magnetic charge density values ​​at all nodes of the series of units of the object to be detected and the detection model. The present invention is suitable for calculating the leakage magnetic field of defects of arbitrary complex shapes, and is fast and low-cost, having significant advantages in the calculation method of sample data for leakage magnetic detection.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field detection, and in particular to a method, device and storage device for quickly calculating leakage magnetic field of an arbitrary defect. Background Art

[0002] Magnetic flux leakage testing technology is based on the phenomenon of magnetic field leakage. The so-called magnetic field leakage phenomenon refers to the phenomenon that after a component made of ferromagnetic material is magnetized, the magnetic permeability of the ferromagnetic material far exceeds that of air. If there is a defect somewhere in the component, the existence of the defect destroys the continuity of the material. In this case, the magnetic lines of force in the magnetic circuit will change to a certain extent. A small part of the magnetic lines of force leaks from the defect of the component being tested into the air near the defect, forming a leakage magnetic field at this location. This technology has the advantages of being relatively simple in principle, easy to apply to actual projects, and having low requirements for the surface cleanliness of the test piece being tested. It plays an important role in the field of non-destructive testing and has been widely used. It is currently the most mature and widely used in-pipeline inspection technology in the industry, and is often used to detect defects in key structures such as long-distance oil and gas pipelines.

[0003] Through magnetic flux leakage detection technology, various defects in pipelines can be analyzed in a targeted manner in terms of shape, size, location, and quantitative statistics. When analyzing the detection data, it is necessary to calculate the corresponding leakage magnetic field distribution based on the defect model. The existing calculation methods mainly include the magnetic dipole model and the finite element method. The magnetic dipole model is simple to calculate and has a fast calculation speed, but its fatal flaw is that it cannot calculate the leakage magnetic field signal of any defect model. The finite element method has strong computing power, but the modeling and calculation process of this method is complex and the calculation cost is high, which makes it impossible to apply it to actual engineering. At present, there is no method in this technical field that can calculate defects of any shape and obtain calculation results efficiently. Summary of the Invention

[0004] The technical problem solved by the present invention is: how to provide an algorithm that can quickly calculate the leakage magnetic field signal of any defect, so as to solve the problems of inability to calculate and high calculation cost existing in existing calculation methods.

[0005] The present invention provides a method for quickly calculating leakage magnetic field of an arbitrary defect, comprising the following steps:

[0006] S1. Based on the actual detection system, a detection model is established. The model includes a magnetizer, an object to be tested, and a detection magnetic field sensor. The object to be tested contains defects of arbitrary shapes.

[0007] S2. Meshing the object to be measured to obtain a series of unit bodies of the meshed object to be measured; S3. Setting magnetization parameters of the magnetizer based on the detection model;

[0008] S4. Calculate the magnetic charge density values ​​at all nodes of the series unit of the object to be tested according to the detection model and magnetizer parameters;

[0009] S5. Calculate the leakage magnetic field of the detection area of ​​the object to be measured according to the magnetic charge density values ​​at all nodes of the series units of the object to be measured and the detection model.

[0010] A storage device stores instructions and data for implementing a fast calculation method for leakage magnetic field of any defect.

[0011] A device for quickly calculating leakage magnetic fields of arbitrary defects comprises: a processor and a storage device; the processor loads and executes instructions and data in the storage device to implement a method for quickly calculating leakage magnetic fields of arbitrary defects.

[0012] The beneficial effects provided by the present invention are: solving the problems of inability to calculate and high calculation cost in existing leakage magnetic field calculation methods, making the calculation cost low and being able to target any defect model. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic flow chart of the method of the present invention.

[0014] Figure 2 1 is a diagram of calculation results of three calculation methods according to a specific embodiment of the present invention;

[0015] Figure 3 It is a schematic diagram of the operation of the hardware device in the embodiment of the present invention. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0017] Please refer to Figure 1 , Figure 1 It is a schematic flow chart of the method of the present invention.

[0018] A method for quickly calculating leakage magnetic field of an arbitrary defect comprises the following steps:

[0019] S1. Based on the actual detection system, a detection model is established. The model includes a magnetizer, an object to be tested, and a detection magnetic field sensor. The object to be tested contains defects of arbitrary shapes.

[0020] It should be noted that the defect model of the present invention is a defect model of any shape; for example, a pipeline leakage model or other weld defect model;

[0021] The defect model can be directly obtained through commercial finite element calculation software; for example, COMSOL, ABAQUS and ANSYS can complete the modeling and divide the model, or the model can be first established using CAD software such as SOLIDWORKS, 3DMAX, etc., and then the defect model can be imported into the above commercial finite element calculation software, or the defect model can be meshed through dedicated meshing software such as HyperMesh. As another way, the defect model meshing open source source code can be adaptively modified according to actual needs.

[0022] The object to be measured is generally the area scanned by the detection probe around the defect; and the detection magnetic field sensor is used to measure the magnetic flux density in the space;

[0023] S2, meshing the object to be measured to obtain a series of unit bodies of the object to be measured after meshing;

[0024] It should be noted that, in the embodiment of the present invention, the series unit body is a tetrahedron unit; in some other embodiments, more different divisions may be performed according to actual conditions;

[0025] The series unit body includes multiple nodes; each node has node coordinate data and node number data;

[0026] S3. Setting magnetization parameters of the magnetizer based on the detection model;

[0027] It should be noted that after importing the model data, because the magnetizer is in motion during the magnetic flux leakage detection process, in order to simulate the motion process, the position of the magnetizing magnetic field changes in the program calculation. Therefore, the magnetizing magnetic field needs to be adjusted before each calculation.

[0028] The parameters of the magnetizer include the size of the end face of the excitation body, the surface magnetic charge density, and the position parameter. The size of the end face of the magnet and the surface magnetic charge density are determined by the excitation body itself and are fixed values. The position parameter is a variable value and is adjusted in real time during the scanning process.

[0029] S4. Calculate the magnetic charge density values ​​at all nodes of the series unit body of the object to be tested based on the detection model and magnetizer parameters;

[0030] It should be noted that before obtaining the magnetic charge density value at the node, the external magnetic field intensity at the centroid of the corresponding tetrahedral unit is obtained according to the parameters of the magnetizer;

[0031] In the calculation, the excitation body is used as the magnetization source, and the surface magnetic charge distributed on its magnetized end face (i.e., the contact surface between the excitation body and the object to be inspected) is used to equate the magnetization source to calculate the magnetic field intensity generated by the excitation body in the series of unit bodies of the object to be inspected.

[0032] Assume that the center coordinates of each element on the contact surface are (x, y, 0), and the length of the contact surface parallel to the y-axis is 2L y , the length of the side parallel to the x-axis is 2L x The surface magnetic charge density distributed on it is σ s .

[0033] The contact surface is mostly rectangular, but not limited to a rectangle. Taking a rectangle as an example, the magnetic charge distribution on the contact surface is at any point coordinate (x f ,y f ,z f ) is the triaxial component H of the magnetic field strength generated at xf 、H yf 、H zf They are:

[0034]

[0035]

[0036] It should be noted that the next step is to enter the node calculation, obtain the data information of an uncalculated node, calculate the magnetizing magnetic field intensity at the centroid of the node, and then form the node control equation and solve it to obtain the magnetic charge contributed by the unit on the node. After calculating one node, obtain the data information of the next unit and continue the calculation until all nodes have completed a calculation.

[0037] The specific calculation formula for solving the magnetic charge density value at the node is:

[0038]

[0039] Where χ is the magnetic susceptibility. ij (i=1,2,3,4;j=x,y,z) are the j-axis components of the distance from each node i to the corresponding unit body centroid, which are calculated from the node coordinate data and the unit centroid coordinate data; H xf 、H yf 、H zf are the x-, y-, and z-axis components of the external magnetic field intensity at the unit centroid, which are calculated by formula (1); f ,y f ,z f ) The magnetic charges at each node are {q 1f ,q 2f ,q 3f ,q 4f}, is the final solution;

[0040] The control equations are linear equations, where {q 1f ,q2f ,q 3f ,q 4f} is an unknown quantity. Solving the linear equations can obtain the magnetic charge of each node. The solution can be programmed using methods such as Gaussian elimination, LU decomposition, and Jacobi iteration in the field of mathematics.

[0041] S5. Calculate the leakage magnetic field of the detection area of ​​the object to be measured according to the magnetic charge density values ​​at all nodes of the series units of the object to be measured and the detection model.

[0042] The distribution of leakage magnetic field is calculated based on the magnetic charge density values ​​at all nodes. The calculation formula is the basic theory of the magnetic charge method.

[0043] Step S5 is specifically as follows: the magnetic charge of each node at all field points {q 1f ,q 2f ,q 3f ,q 4f}, calculate the leakage magnetic field distribution of any field point in the inspection area above the object to be inspected;

[0044] Assume that the object to be inspected has a series of unit field points n, and each field point has m nodes. Then at any field point in the area to be inspected (x k ,y k ,z k ) leakage magnetic field B kj (k=1,2,3…;j=x,y,z) is:

[0045]

[0046] Among them B kj is the leakage magnetic field at any point in the inspection area of ​​the object to be inspected, q i is the magnetic charge on the i-th node of the object to be inspected (i=n*m), r i is the distance from the i-th node to the field point, l i is the vector pointing from the i-th node to the field point.

[0047] As an embodiment, the present invention uses a three-dimensional rectangular defect model with a length, width and height of 5mm, 4mm and 4mm respectively, and the end face dimensions of the excitation body are: length 100mm, width 20mm, and magnetic charge density 100Wb / mm 2 Take this as an example to illustrate.

[0048] A 3D rectangular model with a length, width, and height of 5 mm, 4 mm, and 4 mm was directly created in the commercial finite element software COMSOL. The mesh was then divided into tetrahedral elements and the mesh data was exported. A magnetic flux leakage detection model corresponding to the defect was also created in COMSOL for finite element calculations, obtaining the results of the finite element method.

[0049] According to the above calculation formula and calculation process, you can write a program by yourself, use any programming language, import the grid data into the self-written program for calculation, and you can get the calculation results of the present invention. Figure 2 , Figure 2 The following are the calculation results of three calculation methods for a specific embodiment of the present invention; comparing these results with the existing magnetic dipole model calculation results and the finite element method calculation results calculated by COMSOL can illustrate the effectiveness of the present invention. The comparison results are as follows:

[0050] Table 1 Root mean square error between the calculation results of the present invention and the existing method

[0051] method Bx By Bz Finite Element Method 1.86％ 2.34％ 1.63％ Magnetic dipole model 0.15％ 0.28％ 0.16％

[0052] See Figure 3 , Figure 3 4 is a schematic diagram of the working of the hardware device of an embodiment of the present invention, wherein the hardware device specifically comprises: a fast calculation device 401 of leakage magnetic field of any defect, a processor 402 and a storage device 403.

[0053] A device 401 for quickly calculating leakage magnetic field of an arbitrary defect: the A device 401 implements the A method.

[0054] Processor 402: The processor 402 loads and executes instructions and data in the storage device 403 to implement the method for quickly calculating leakage magnetic field of an arbitrary defect.

[0055] Storage device 403: The storage device 403 stores instructions and data; the storage device 403 is used to implement the method for quickly calculating the leakage magnetic field of an arbitrary defect.

[0056] The beneficial effects of the present invention are: solving the problems of incomputation and high calculation cost in existing leakage magnetic field calculation methods, making the calculation cost low and being able to target any defect model.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for rapidly calculating leakage magnetic field of an arbitrary defect, characterized by: include: S1. Based on the actual detection system, a detection model is established. The model includes a magnetizer, an object to be tested, and a detection magnetic field sensor. The object to be tested contains defects of arbitrary shapes. S2, meshing the object to be measured to obtain a series of unit bodies of the object to be measured after meshing; The series unit body includes multiple nodes; each node has node coordinate data and node number data; S3. Setting magnetization parameters of the magnetizer based on the detection model; S4. Calculate the magnetic charge density values ​​at all nodes of the series unit body of the object to be tested based on the detection model and magnetizer parameters; S5. Calculate the leakage magnetic field of the detection area of ​​the object to be tested based on the magnetic charge density values ​​at all nodes of the series unit of the object to be tested and the detection model; In step S4, first, the external magnetic field intensity at the centroid of the series unit body of the object to be inspected is obtained according to the parameters of the magnetizer; The coordinates of any field point at the centroid of the series unit of the object to be inspected (x f ,y f ,z f ) The three-axis components of the magnetic field strength H xf 、H yf 、H zf They are: Among them, the center coordinates of each unit of the contact surface between the object to be tested and the excitation body are (x, y, 0), and the length of the contact surface parallel to the y axis is 2L y , the length of the side parallel to the x-axis is 2L x The surface magnetic charge density distributed on it is σ s .

2. The method for rapidly calculating leakage magnetic field of an arbitrary defect according to claim 1, wherein: In step S3, the parameters of the magnetizer include the size of the end face of the excitation body, the surface magnetic charge density and the position parameter; the size of the end face of the magnet and the surface magnetic charge density are determined by the excitation body in the magnetizer itself and are fixed values; the position parameter is a variable value and is adjusted in real time during the scanning process.

3. The method for rapidly calculating leakage magnetic field of an arbitrary defect according to claim 1, wherein: The specific calculation formula for solving the magnetic charge density value at the node of the series unit of the object to be tested in step S4 is: Where χ is the magnetic susceptibility; r ij , i = 1, 2, 3, 4; j = x, y, z are the j-axis components of the distance from each node i to the corresponding unit body centroid, which are calculated from the node coordinate data and the unit centroid coordinate data; H xf 、H yf 、H zf are the x-, y-, and z-axis components of the external magnetic field intensity at the cell centroid, calculated by formula (1); Any point of the object to be measured (x f ,y f ,z f ) The magnetic charges at each node are {q 1f ,q 2f ,q 3f ,q 4f }, which is the final solution.

4. The method for rapidly calculating leakage magnetic field of an arbitrary defect according to claim 1, wherein: Step S5 is specifically as follows: the magnetic charge of each node at all field points {q 1f ,q 2f ,q 3f ,q 4f }, calculate the leakage magnetic field distribution of any field point in the inspection area above the object to be inspected; Assume that the object to be inspected has a series of unit field points n, and each field point has m nodes. Then at any field point in the area to be inspected (x k ,y k ,z k ) leakage magnetic field B kj , k=1,2,3…;j=x,y,z is: Among them B kj is the leakage magnetic field at any point in the inspection area of ​​the object to be inspected, q i is the magnetic charge on the i-th node of the object to be tested, i=n*m, r i is the distance from the i-th node to the field point, l i is the vector pointing from the i-th node to the field point.

5. A storage device, characterized in that: The storage device stores instructions and data for implementing a method for rapidly calculating leakage magnetic field of an arbitrary defect as claimed in any one of claims 1 to 4.

6. A method and apparatus for rapidly calculating leakage magnetic field of an arbitrary defect, characterized by: include: A processor and a storage device; the processor loads and executes instructions and data in the storage device to implement a method for quickly calculating leakage magnetic field of an arbitrary defect as described in any one of claims 1 to 4.

Images