CN107817290B - Defect magnetic flux leakage signal solving method based on depth-lift-off value transformation - Google Patents
Defect magnetic flux leakage signal solving method based on depth-lift-off value transformation Download PDFInfo
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Abstract
The invention discloses a method for solving a defect flux leakage signal based on depth-lift-off value transformation, which comprises the following steps of: s1: determining the defect size and the lift-off value t of the surface of the substance corresponding to the defect magnetic leakage signal to be solved; s2: dividing the defect of the defect leakage magnetic signal to be solved into n sub-defects with equal depth along the direction of the defect depth, and determining the basic sub-defects from the n sub-defects; s3: respectively carrying out depth-extraction value transformation on the defect magnetic flux leakage signals corresponding to the n sub-defects at the extraction value t, and solving the defect magnetic flux leakage signals corresponding to the n sub-defects in different depth ranges at the extraction value t to obtain an extraction value sequence Tn; s4: acquiring defect flux leakage signals corresponding to the basic sub-defects at different lift-off values according to the lift-off value sequence Tn; s5: and carrying out combined operation on the defect flux leakage signals corresponding to the basic sub-defects at different lift-off values to obtain the defect flux leakage signal to be solved. The invention has the advantages of high calculation speed and high calculation precision.
Description
Technical Field
The invention relates to the technical field of nondestructive testing, in particular to a method for solving a defect magnetic flux leakage signal based on depth-lift-off value transformation.
Background
The magnetic flux leakage detection is a nondestructive detection technology which is generally applied to the defect detection and evaluation of ferromagnetic materials, and has the advantages of high online detection speed, high reliability, low requirement on detection environment and the like. Analyzing the detected defect leakage magnetic signal, and further realizing defect quantification or imaging is one of important applications of leakage magnetic detection. The quantification or imaging of defects usually adopts a closed loop iterative structure, wherein the most important link is to construct a forward model and solve a corresponding defect leakage magnetic signal according to a given defect size. For solving the defect magnetic leakage signal, in the current related technology, for example, in the three-dimensional magnetic leakage detection defect contour reconstruction method, a forward finite element calculation model is adopted to solve the defect magnetic leakage signal, the finite element calculation process is complex, the calculation time is long, and the efficiency is low; for example, the three-dimensional magnetic flux leakage detection defect compound inversion imaging method adopts a forward finite element neural network model and a forward finite element calculation model to solve defect magnetic flux leakage signals in sequence, although the method has high calculation precision, the calculation speed is slow, and model calculation needs to be carried out again when the magnetic flux leakage signals of the defects with different sizes are solved, so that the efficiency is low.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems.
Therefore, the invention aims to provide a method for solving the defect magnetic leakage signal based on the depth-lift-off value transformation, which can effectively solve the defect magnetic leakage signal and has the advantages of high calculation speed and high calculation precision.
The embodiment of the invention discloses a method for solving a defect magnetic leakage signal based on depth-lift-off value transformation, which comprises the following steps: s1: determining the defect size and the lift-off value t of the surface of the substance corresponding to the leakage flux signal of the defect to be solved, wherein the defect size of the surface of the substance comprises defect length, defect width and defect depth; s2: dividing the defect of the to-be-solved defect magnetic leakage signal into n sub-defects with equal depth along the direction of the defect depth, and determining a basic sub-defect from the n sub-defects; s3: respectively carrying out depth-extraction value transformation on the defect magnetic flux leakage signals corresponding to the n sub-defects at the extraction value t, and solving the defect magnetic flux leakage signals corresponding to the n sub-defects at the extraction value t in different depth ranges to obtain an extraction value sequence Tn; s4: acquiring a defect flux leakage signal corresponding to the basic sub-defect at different lift-off values according to the lift-off value sequence Tn; s5: and carrying out combined operation on the defect magnetic leakage signals corresponding to the basic sub-defects at different lift-off values to obtain the defect magnetic leakage signal to be solved.
According to the method for solving the defect magnetic leakage signal based on the depth-lift-off value transformation, the defect magnetic leakage signals corresponding to the sub-defects in different depth ranges can be solved and converted into the corresponding combination of the defect magnetic leakage signals of the basic sub-defects under different lift-off values, and the same basic sub-defects can be selected for the defects with the same length and width and different depths.
In addition, the method for solving the defect leakage magnetic signal based on the depth-lift-off value transformation according to the above embodiment of the present invention may further have the following additional technical features:
in some examples, prior to said S1, further comprising: and carrying out saturation magnetization treatment by adopting a direct-current magnetization field on the surface of the substance corresponding to the leakage magnetic signal of the defect to be solved so as to determine the size of the defect on the surface of the substance to be solved.
In some examples, the direction of the defect length is a magnetization direction along a surface of the substance corresponding to the leakage magnetic signal to be solved, the direction of the defect depth is a thickness direction along the surface of the substance corresponding to the leakage magnetic signal to be solved, and the direction of the defect width is a plane perpendicular to the direction of the defect length and the direction of the defect depth.
In some examples, n is greater than or equal to 2 of the n sub-defects, and the length and width of each sub-defect are equal to the defect length and defect width of the material surface corresponding to the to-be-solved defect leakage magnetic signal, the defect depths of the n sub-defects are all d/n, and the depth ranges of the n sub-defects are: [0, -d/n ], [ -d/n, -2d/n ], [ - (n-1) d/n, -d ], wherein the sub-defects having a depth range of [0, -d/n ] are basic sub-defects.
In some examples, the depth-extraction value transformation is performed on the defect leakage flux signals corresponding to the n sub-defects at the extraction value t, where the depth-extraction value transformation satisfies the following equation:
B(-kd/n,-(k+1)d/n,t)＝B(0,-d/n,t+kd/n)，
wherein B (-kd/n, - (k +1) d/n, t) represents a defect leakage magnetic signal corresponding to a sub-defect having a depth range of [ -kd/n, - (k +1) d/n ] at an extraction value of t, B (0, -d/n, t + kd/n) represents a defect leakage magnetic signal corresponding to a sub-defect having a depth range of [0, -d/n ] at an extraction value of t + kd/n, k is 0, 1.
In some examples, the sequence of lift-off values Tn contains a total of n elements and satisfies the following equation:
Tn＝[t,t+d/n,...,t+kd/n,...,t+d]，k＝0,1,...,n-1。
in some examples, the method for acquiring the defect leakage magnetic signals corresponding to the basic sub-defects at different lift-off values includes: the method comprises an analytic calculation method, a numerical calculation method and a manual test method, wherein the analytic calculation method is to calculate and obtain a corresponding defect leakage magnetic signal according to the following formula based on a magnetic dipole model:
b (0, -d/n, T) represents a defect magnetic leakage signal corresponding to the basic sub-defect at the position where the lift-off value is T, and the numerical calculation method is to calculate and obtain the corresponding defect magnetic leakage signal by establishing a finite element numerical simulation model; the manual test method is characterized in that a magnetic flux leakage detection test is carried out on a ferromagnetic plate or pipe with manual excavation defects, and a magnetic flux leakage signal of the defects is obtained through detection of a magnetic sensor at different lift-off values.
In some examples, the combining operation is to add the corresponding magnetic leakage flux signals of the basic sub-defect at different lift-off values, and multiply the corresponding magnetic leakage flux signals by a correction coefficient p, where a value range of p is [0.9,1.3], and a resulting magnetic leakage flux signal B of the defect to be solved satisfies the following calculation formula:
additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flowchart of a method for solving a leakage flux signal of a defect based on a depth-lift-off transformation according to an embodiment of the present invention;
FIG. 2(a) is a schematic top view of a ferromagnetic material and its defects tested according to one embodiment of the present invention;
FIG. 2(b) is a schematic side view of a ferromagnetic material and its defects tested according to one embodiment of the present invention;
FIG. 3 is a graph of a leakage flux signal of a fundamental sub-defect at different lift-off values according to an embodiment of the present invention;
FIG. 4 is a comparison graph of the results of solving for 24mm × 24mm × 4.8mm leakage flux signals for defects according to an embodiment of the present invention;
FIG. 5 is a comparison graph of the results of solving for 24mm × 24mm × 2.4mm defect leakage flux signals according to another embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
These and other aspects of embodiments of the invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the embodiments of the invention may be practiced, but it is understood that the scope of the embodiments of the invention is not limited correspondingly. On the contrary, the embodiments of the invention include all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto.
The following describes a method for solving the cell combination of the perpendicular magnetization direction of the leakage magnetic signals of the defects according to an embodiment of the present invention with reference to the drawings.
Fig. 1 is a flowchart of a method for solving a leakage flux signal of a defect based on depth-lift-off value transformation according to an embodiment of the present invention. As shown in fig. 1, the method comprises the steps of:
step S1: and determining the defect size and the lift-off value t of the material surface corresponding to the defect leakage magnetic signal to be solved, wherein the defect size of the material surface comprises defect length, defect width and defect depth.
In some embodiments, the direction of the defect length is a magnetization direction along the surface of the substance corresponding to the leakage magnetic signal of the defect to be solved, the direction of the defect depth is a thickness direction along the surface of the substance corresponding to the leakage magnetic signal of the defect to be solved, and the direction of the defect width is a plane in which the direction perpendicular to the defect length and the direction of the defect depth are located.
Specifically, as described in conjunction with fig. 2(a) and fig. 2(b), the defect size corresponding to the leakage magnetic signal of the defect to be solved includes the length l, the width w and the depth d of the defect. Under an xyz coordinate system, the length direction of the defect is along the magnetization direction of the measured material, the length of the defect is-l/2 to l/2, the depth direction of the defect is along the thickness direction of the measured material, the depth of the defect is-d, the width direction of the defect is vertical to the plane where the length direction and the depth direction of the defect are located, and the width of the defect is-w/2 to w/2.
Before the S1, the method further includes: and performing saturation magnetization treatment on the surface of the substance corresponding to the flux leakage signal of the defect to be solved by adopting a direct-current magnetization field so as to determine the size of the defect on the surface of the substance to be solved.
Specifically, the defect corresponding to the leakage magnetic signal of the defect to be solved is located on the surface of the ferromagnetic material (plate or pipe) to be tested, and the ferromagnetic material to be tested is subjected to saturation magnetization treatment by using a direct-current magnetization field.
Step S2: dividing the defect of the defect leakage magnetic signal to be solved into n sub-defects with equal depth along the direction of the defect depth, and determining the basic sub-defects from the n sub-defects.
In some embodiments, n is greater than or equal to 2, and the length and width of each sub-defect are equal to the defect length and defect width of the material surface corresponding to the leakage flux signal of the defect to be solved, the defect depths of the n sub-defects are all d/n, and the depth ranges of the n sub-defects are sequentially: [0, -d/n ], [ -d/n, -2d/n ], [ - (n-1) d/n, -d ], wherein the sub-defects having a depth range of [0, -d/n ] are basic sub-defects.
Step S3: and respectively carrying out depth-extraction value transformation on the defect magnetic flux leakage signals corresponding to the n sub-defects at the extraction value t, and solving the defect magnetic flux leakage signals corresponding to the n sub-defects in different depth ranges at the extraction value t to obtain an extraction value sequence Tn.
In some embodiments, depth-extraction value transformation is performed on the defect leakage magnetic signals corresponding to the n sub-defects at the extraction value t, where the depth-extraction value transformation satisfies the following equation:
B(-kd/n,-(k+1)d/n,t)＝B(0,-d/n,t+kd/n)，
wherein B (-kd/n, - (k +1) d/n, t) represents a defect leakage magnetic signal corresponding to a sub-defect having a depth range of [ -kd/n, - (k +1) d/n ] at an extraction value of t, B (0, -d/n, t + kd/n) represents a defect leakage magnetic signal corresponding to a sub-defect having a depth range of [0, -d/n ] at an extraction value of t + kd/n, k is 0, 1.
In some embodiments, the sequence of lift-off values Tn comprises a total of n elements and satisfies the following equation:
Tn＝[t,t+d/n,...,t+kd/n,...,t+d]，k＝0,1,...,n-1。
step S4: and acquiring the defect flux leakage signals corresponding to the basic sub-defects at different lift-off values according to the lift-off value sequence Tn.
In some embodiments, the method for obtaining the defect leakage magnetic signals corresponding to the basic sub-defects at different lift-off values includes: the method comprises an analytic calculation method, a numerical calculation method and a manual test method, wherein the analytic calculation method is to calculate and obtain a corresponding defect leakage magnetic signal according to the following formula based on a magnetic dipole model:
b (0, -d/n, T) represents a defect leakage signal corresponding to the basic sub-defect at the lift-off value T,
the numerical calculation method is to calculate and obtain a corresponding defect magnetic leakage signal by establishing a finite element numerical simulation model;
the manual test method is to carry out a magnetic flux leakage detection test on ferromagnetic plates or pipes with defects cut manually, and detect the ferromagnetic plates or pipes at different lift-off values through a magnetic sensor to obtain defect magnetic flux leakage signals.
Step S5: and carrying out combined operation on the defect flux leakage signals corresponding to the basic sub-defects at different lift-off values to obtain the defect flux leakage signal to be solved.
In some embodiments, the combining operation is to add the corresponding defect leakage magnetic signals of the basic sub-defect at different lift-off values, and multiply the added defect leakage magnetic signals by a correction coefficient p, where a value range of p is [0.9,1.3], and an obtained defect leakage magnetic signal B to be solved satisfies the following calculation formula:
in summary, according to the method for solving the defect leakage magnetic signals based on the depth-extraction value transformation of the embodiment of the present invention, the defect leakage magnetic signals corresponding to the sub-defects in different depth ranges can be solved and converted into the corresponding combination of the defect leakage magnetic signals of the basic sub-defects in different extraction values, and the same basic sub-defects can be selected for the defects with the same length and width but different depths.
In order to better understand the present invention, the following describes an exemplary method for solving the combination of the perpendicular magnetization direction units of the leakage magnetic signals of the defect in detail with reference to the accompanying drawings and specific embodiments.
Example 1
In this embodiment, the method includes the steps of:
1. and determining the defect size and the lift-off value information corresponding to the defect leakage magnetic signal to be solved. The defect corresponding to the defect leakage signal to be solved is positioned on the surface of the ferromagnetic plate to be tested, the ferromagnetic plate is subjected to saturation magnetization treatment by adopting a direct-current magnetization field, and the thickness of the plate can be 12 mm. The defect leakage signal to be solved may correspond to a defect length l of 24mm, a width w of 24mm, a depth d of 4.8mm, and a signal lift-off value t of 2 mm.
2. And dividing the defect corresponding to the defect magnetic leakage signal to be solved into 4 sub-defects with equal depth along the depth direction. The length of these 4 "sub-defects" all can be 24mm, and the width all can be 24mm, and is equal with the length and the width of the defect that the defect magnetic leakage signal that waits to solve corresponds, and the degree of depth all can be 1.2mm, and the depth range of these 4 "sub-defects" is in proper order: [0mm, -1.2mm ], [ -1.2mm, -2.4mm ], [ -2.4mm, -3.6mm ], [ -3.6mm, -4.8mm ]. Among them, the "sub-defects" having a depth ranging from 0mm to-1.2 mm are called basic sub-defects.
3. And respectively carrying out depth-extraction value transformation operation on the defect magnetic leakage signals corresponding to the 4 sub-defects at the extraction value t, converting the defect magnetic leakage signals corresponding to the sub-defects with the solved 4 different depth ranges at the extraction value t of 2mm into the defect magnetic leakage signals corresponding to the basic sub-defects at different extraction values, and obtaining an extraction value sequence Tn. A depth-lift-off transformation operation satisfying the following equation:
B(-kd/n,-(k+1)d/n,t)＝B(0,-d/n,t+kd/n)
where d is 1.2mm, t is 2mm, n is 4, k is 0,1,2, 3. B (-kd/n, - (k +1) d/n, t) represents a defect leakage signal corresponding to a sub-defect having a depth range of [ -kd/n, - (k +1) d/n ] at an extraction value of t, and B (0, -d/n, t + kd/n) represents a defect leakage signal corresponding to a sub-defect having a depth range of [0, -d/n ] at an extraction value of t + kd/n.
The extracted value sequence contains 4 elements in total, and Tn is [2mm,3.2mm,4.4mm,5.6mm ].
4. And obtaining the defect flux leakage signals corresponding to the basic sub-defects at different lift-off values by adopting a numerical calculation method according to the lift-off value sequence Tn. By establishing a finite element numerical simulation model, basic sub-defects with the length of 2.4mm, the width of 2.4mm and the depth range of [0mm to-1.2 mm ] are obtained through simulation calculation, and the defect leakage magnetic signal curve graphs are shown in figure 3, wherein the defect leakage magnetic signals correspond to the positions with the lift-off values of 2mm,3.2mm,4.4mm and 5.6mm respectively.
5. And combining the obtained defect magnetic leakage signals corresponding to the basic sub-defects at different lift-off values, namely adding the defect magnetic leakage signals obtained by the basic sub-defects at different lift-off values, multiplying the added defect magnetic leakage signals by a correction coefficient, and taking 1.24 as the correction coefficient p to obtain a defect magnetic leakage signal B to be solved, wherein the obtained defect magnetic leakage signal B satisfies the following calculation formula:
where p is 1.24, d is 1.2mm, t is 2mm, n is 4, k is 0,1,2, 3.
In this example, a comparison graph of a defect leakage magnetic signal corresponding to a defect with a size l of 24mm, w of 24mm, and d of 4.8mm at a lift-off value t of 2mm obtained by the method of the embodiment of the present invention and a defect leakage magnetic signal curve obtained by direct finite element method calculation is shown in fig. 4. In addition, in the present embodiment, the defect leakage magnetic signals corresponding to 4 "sub-defects" in different depth ranges are solved and converted into the corresponding combination of the defect leakage magnetic signals of the basic sub-defects at 4 different lift-off values, and for the defects with the same length and width but different depths (such as the defect with l ═ 24mm, w ═ 24mm, d ═ 4.8mm and the defect with l ═ 24mm, w ═ 24mm, d ═ 2.4 mm), the same basic sub-defects (with l ═ 24mm, w ═ 24mm, d ═ 1.2mm, and depth range [0mm, -1.2mm ]) can be selected. Therefore, according to the defect leakage signal solving method provided by the embodiment of the invention, when the defect leakage signals at different depths are solved, the construction and calculation of complex models such as finite elements are not required to be carried out again, and only the defect leakage signals of basic sub-defects at different lift-off values are required to be combined, so that the defect leakage signals at different depths can be obtained, the signal solving process is effectively simplified, and the solving time is remarkably reduced.
Example 2
In this embodiment, a method for solving a defect leakage magnetic signal based on depth-lift-off value transformation includes the following steps:
1. and determining the defect size and the lift-off value information corresponding to the defect leakage magnetic signal to be solved. The defect corresponding to the defect leakage signal to be solved is positioned on the surface of the ferromagnetic plate to be tested, the ferromagnetic plate is subjected to saturation magnetization treatment by adopting a direct-current magnetization field, and the thickness of the plate can be 12 mm. The defect leakage signal to be solved may correspond to a defect length l of 24mm, a width w of 24mm, a depth d of 2.4mm, and a signal lift-off value t of 2 mm.
2. And dividing the defect corresponding to the defect magnetic leakage signal to be solved into 2 sub-defects with equal depth along the depth direction. The length of these 2 "sub-defects" all can be 24mm, and the width all can be 24mm, and is equal with the length and the width of the defect that the defect magnetic leakage signal that waits to solve corresponds, and the degree of depth all can be 1.2mm, and the depth range of these 2 "sub-defects" is in proper order: [0mm, -1.2mm ], [ -1.2mm, -2.4mm ]. Among them, the "sub-defects" having a depth ranging from 0mm to-1.2 mm are called basic sub-defects.
3. And respectively carrying out depth-extraction value transformation operation on the defect magnetic leakage signals corresponding to the 2 sub-defects at the extraction value t, converting the defect magnetic leakage signals corresponding to the sub-defects in the extraction value t-2 mm for solving 2 different depth ranges into the defect magnetic leakage signals corresponding to the basic sub-defects at different extraction values, and obtaining an extraction value sequence Tn. A depth-lift-off transformation operation satisfying the following equation:
B(-kd/n,-(k+1)d/n,t)＝B(0,-d/n,t+kd/n)
where d is 1.2mm, t is 2mm, n is 2, and k is 0, 1. B (-kd/n, - (k +1) d/n, t) represents a defect leakage signal corresponding to a sub-defect having a depth range of [ -kd/n, - (k +1) d/n ] at an extraction value of t, and B (0, -d/n, t + kd/n) represents a defect leakage signal corresponding to a sub-defect having a depth range of [0, -d/n ] at an extraction value of t + kd/n.
The extracted value sequence Tn contains 2 elements in total, and is Tn ═ 2mm,3.2mm respectively.
4. And obtaining the defect flux leakage signals corresponding to the basic sub-defects at different lift-off values by adopting a numerical calculation method according to the lift-off value sequence Tn. In embodiment 1, a finite element numerical simulation model is already established, a basic sub-defect with a length of 2.4mm, a width of 2.4mm and a depth range of [0mm, -1.2mm ] is obtained through simulation calculation, and corresponding defect leakage magnetic signals at different lift-off values are obtained, because the basic sub-defect selected in embodiment 2 is the same as the basic sub-defect selected in embodiment 1, finite element modeling and calculation do not need to be performed again, and the simulation result in embodiment 1 can be directly adopted to obtain corresponding defect leakage magnetic signals of the basic sub-defect at the lift-off values of 2mm and 3.2mm respectively.
5. And combining the obtained defect magnetic leakage signals corresponding to the basic sub-defects at different lift-off values, namely adding the defect magnetic leakage signals obtained by the basic sub-defects at different lift-off values, multiplying the added defect magnetic leakage signals by a correction coefficient, and taking 1.08 as the correction coefficient p to obtain a defect magnetic leakage signal B to be solved, wherein the obtained defect magnetic leakage signal B satisfies the following calculation formula:
where p is 1.08, d is 1.2mm, t is 2mm, n is 2, k is 0, 1.
In this example, a comparison graph of a defect leakage magnetic signal corresponding to a defect with a size l of 24mm, w of 24mm, and d of 2.4mm at a lift-off value t of 2mm obtained by the method of the embodiment of the present invention and a defect leakage magnetic signal curve obtained by direct finite element method calculation is shown in fig. 5. In addition, in this embodiment, a depth-extraction value transformation method is adopted to solve and convert the defect leakage magnetic signals corresponding to 2 sub-defects in different depth ranges into a combination of the defect leakage magnetic signals of corresponding basic sub-defects at 2 different extraction values, since the basic sub-defects selected in this example 2 are the same as those selected in example 1 (i.e., 24mm, w.24 mm, d.1.2 mm, depth range of [0mm, -1.2mm ]), therefore, when the defect magnetic signal is solved in the embodiment, the construction and calculation of complex models such as finite elements and the like are not required to be carried out again, only the defect leakage magnetic signals of basic sub-defects under different lift-off values are required to be combined, and defect magnetic flux leakage signals of different depths can be obtained, the signal solving process is effectively simplified, and the solving time is obviously reduced.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (7)
1. A method for solving a defect magnetic leakage signal based on depth-extraction value transformation is characterized by comprising the following steps:
s1: determining the defect size and the lift-off value t of the surface of the substance corresponding to the defect leakage magnetic signal to be solved, wherein the defect size of the surface of the substance comprises a defect length l, a defect width w and a defect depth d;
s2: dividing the defect of the to-be-solved defect magnetic leakage signal into n sub-defects with equal depth along the direction of the defect depth, and determining a basic sub-defect from the n sub-defects;
s3: respectively carrying out depth-extraction value transformation on the defect magnetic flux leakage signals corresponding to the n sub-defects at the extraction value t, and solving the defect magnetic flux leakage signals corresponding to the n sub-defects at the extraction value t in different depth ranges to obtain an extraction value sequence Tn;
s4: acquiring a defect flux leakage signal corresponding to the basic sub-defect at different lift-off values according to the lift-off value sequence Tn;
s5: and carrying out combined operation on the defect magnetic leakage signals corresponding to the basic sub-defects at different lift-off values to obtain the defect magnetic leakage signal to be solved.
2. The method for solving the defect leakage magnetic signal based on the depth-extraction value transformation as claimed in claim 1, further comprising, before said S1: and carrying out saturation magnetization treatment by adopting a direct-current magnetization field on the surface of the substance corresponding to the leakage magnetic signal of the defect to be solved so as to determine the size of the defect on the surface of the substance to be solved.
3. The method according to claim 1, wherein the direction of the defect length is along a magnetization direction of a material surface corresponding to the defect leakage magnetic signal to be solved, the direction of the defect depth is along a thickness direction of the material surface corresponding to the defect leakage magnetic signal to be solved, and the direction of the defect width is perpendicular to the direction of the defect length and the plane of the direction of the defect depth.
4. The method according to claim 1, wherein n is greater than or equal to 2 among the n sub-defects, the length and width of each sub-defect are equal to the defect length and defect width of the material surface corresponding to the defect leakage signal to be solved, the defect depths of the n sub-defects are d/n, and the depth ranges of the n sub-defects are sequentially: [0, -d/n ], [ -d/n, -2d/n ], [ - (n-1) d/n, -d ], wherein the sub-defects having a depth range of [0, -d/n ] are basic sub-defects.
5. The method according to claim 1, wherein the depth-lift-off value transformation is performed on the leakage flux signals corresponding to the n sub-defects at the lift-off value t, and the depth-lift-off value transformation satisfies the following equation:
B(-kd/n,-(k+1)d/n,t)＝B(0,-d/n,t+kd/n)，
wherein B (-kd/n, - (k +1) d/n, t) represents a defect leakage magnetic signal corresponding to a sub-defect having a depth range of [ -kd/n, - (k +1) d/n ] at an extraction value of t, B (0, -d/n, t + kd/n) represents a defect leakage magnetic signal corresponding to a sub-defect having a depth range of [0, -d/n ] at an extraction value of t + kd/n, k is 0, 1.
6. The method for solving the defect leakage magnetic signal based on the depth-extraction value transformation as claimed in claim 1, wherein the extraction value sequence Tn contains n elements in total and satisfies the following equation:
Tn＝[t,t+d/n,...,t+kd/n,...,t+d]，k＝0,1,...,n-1。
7. the method according to claim 1, wherein the combination operation is to add the corresponding magnetic leakage signals of the basic sub-defects at different lift-off values, and multiply the added signals by a correction coefficient p, where the value range of p is [0.9,1.3], and the obtained magnetic leakage signal B to be solved satisfies the following calculation formula:
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