A stress quantification magnetic measurement device and method based on demagnetization correction

Abstract

The present invention discloses a magnetic measurement device and method for quantifying stress based on demagnetization correction. The device specifically includes: a closed-circuit measurement unit and an open-circuit measurement unit; the closed-circuit measurement unit includes: an excitation circuit, a detection circuit, an excitation coil, a detection coil, and a standard closed-circuit sample; the open-circuit measurement unit includes: an excitation circuit, a detection circuit, an excitation coil, a detection coil, and an object to be measured; the connection method of the components of the closed-circuit measurement unit is consistent with that of the open-circuit measurement unit. The method mainly performs demagnetization correction on the measurement results of the open-circuit measurement unit based on the measurement results obtained by the closed-circuit measurement unit to obtain the true magnetic properties of the measured material; and extracts characteristic parameters from the corrected magnetic measurement results, and uses them to quantitatively evaluate stress. The beneficial effects of the present invention are: it can effectively consider the influence of the demagnetization effect and quantitatively characterize tensile stress through the true magnetic properties of ferromagnetic materials; it is reliable and fast, easy to operate, not affected by the environmental magnetic field, and the measurement results are stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of stress and magnetic field detection in electromagnetic nondestructive testing, and particularly relates to a stress quantification magnetic measurement device based on low demagnetization correction and a measurement method thereof. Background Art

[0002] Ferromagnetic materials have been widely used in many engineering practices due to their excellent mechanical properties. The research on the magnetic properties and applications of ferromagnetic materials has also attracted the attention of many scholars.

[0003] In practical engineering applications, ferromagnetic materials are often used in environments where stress fields and external magnetic fields coexist. Under the coupling of stress and external magnetic fields, the macroscopic hysteresis characteristics of ferromagnetic materials will undergo significant changes. This is one of the important magnetic properties of ferromagnetic materials - the magnetomechanical coupling effect.

[0004] Understanding the magnetomechanical coupling effect is of great theoretical significance for the practical application of ferromagnetic materials in engineering. For example, the vibration, noise, and hysteresis loss problems that exist in electromechanical equipment such as motors and transformers during actual use are closely related to the magnetomechanical coupling effect of the motor core.

[0005] Furthermore, in electromagnetic nondestructive testing (EMNDT), the magnetomechanical coupling effect is the fundamental principle underlying stress magnetic measurement of ferromagnetic materials. However, due to a lack of relevant regulatory guidance, there are currently no regulations for standard specimens used in ferromagnetic material magnetomechanical coupling testing. This makes it difficult to fully understand the impact of the demagnetization field on test results.

[0006] In static magnetometry measurements of ferromagnetic materials, standard ring-shaped samples are typically used for these measurements, i.e., closed-loop measurements. However, in magnetomechanical coupling measurements, since the sample must be mechanically loaded simultaneously, conventional ring-shaped samples are insufficient, and therefore strip (or ribbon) samples are required.

[0007] The magnetic flux loop of a strip (or ribbon) sample is typically uneven and cannot be closed, hence the name "open-circuit measurement." Existing techniques for correcting the demagnetization effect and correction methods for open-circuit measurements of strip (or ribbon) samples are only applicable to static magnetometry measurements, and require the following prerequisites to be met:

[0008] 1) The entire sample must be placed in a solenoid (excitation coil) of sufficient length;

[0009] 2) A relatively uniform external magnetic field must be formed inside the solenoid. This makes this method unable to meet the requirements of mechanical loading. If mechanical loading is required, the sample length will inevitably be longer than the solenoid length, making this method unsuitable. Furthermore, in open-circuit force magnetic coupling measurements, relevant scholars have proposed a method in which a magnetic yoke can be clamped in the middle of the sample during tensile loading to form a closed magnetic flux loop. However, this method is significantly affected by the material properties of the yoke itself—parameters such as the yoke's remanence, coercive force, and magnetic permeability all significantly affect the measurement results. Summary of the Invention

[0010] To address the technical issues of annular standard samples (capable of forming a closed uniform loop) being unable to undergo mechanical loading and strip (or ribbon) tensile samples or objects of actual shape being significantly deviated from their true magnetic material properties (affected by the demagnetization field), the present application provides a stress quantification magnetic measurement device and method based on demagnetization correction. The device specifically comprises:

[0011] Closed-circuit measurement unit and open-circuit measurement unit;

[0012] The closed-circuit measurement unit includes: a first basic measurement unit and a first test object; wherein the first basic measurement unit includes an excitation circuit, a detection circuit, an excitation coil and a detection coil; the test object is a standard closed-circuit sample;

[0013] The open circuit measurement unit includes: a second basic measurement unit and a second test object; wherein the second basic measurement unit includes an excitation circuit, a detection circuit, an excitation coil and a detection coil; the second test object is an open circuit measurement sample or an object to be measured;

[0014] The standard closed-circuit sample is closed; the open-circuit measurement sample or the object to be measured is open;

[0015] Except that the standard closed-circuit sample of the closed-circuit measurement unit is different from the open-circuit measurement sample or the object to be measured of the open-circuit measurement unit, the component parameters, connection mode, excitation parameters and detection parameters of the closed-circuit measurement unit and the first basic measurement unit and the second basic measurement unit of the open-circuit measurement unit are consistent;

[0016] The measurement results obtained by the closed-circuit measurement unit are used to perform demagnetization correction on the measurement results of the open-circuit measurement unit to obtain the true magnetic properties of the measured material;

[0017] The excitation circuit and the detection circuit are inductively connected via an excitation coil and a detection coil wound around a standard closed-circuit sample, an open-circuit measurement sample or an object to be measured;

[0018] The excitation circuit provides the sample with an alternating external magnetic field H0 with a fixed frequency, and is composed of an excitation power supply, an excitation circuit resistor, and an excitation circuit voltmeter or other device capable of measuring voltage;

[0019] The detection circuit is used to collect the magnetic flux density change signal inside the sample, and is composed of a detection circuit resistor, a detection circuit capacitor, and a detection circuit voltmeter or other device that can measure voltage.

[0020] The specific method is as follows:

[0021] The method comprises the following steps:

[0022] S1. Using the closed-circuit measurement unit, test a standard closed-circuit measurement sample to obtain a standard BH curve of the sample material.

[0023] S2. Using the open-circuit measurement unit, test open-circuit samples without stress and with a series of stresses to obtain their nominal BH curves; using the standard BH curve obtained in S1, calibrate the nominal BH curve of the open-circuit sample to obtain its standard BH curve; extract stress-sensitive magnetic parameters from the calibrated standard BH curve and establish a relationship between the magnetic parameters and the known stress, which is the calibration relationship between the magnetic parameters and stress of the sample material;

[0024] S3. Using the same open-circuit measurement unit as in S2, test the stress-free and possibly stressed objects to obtain their nominal BH curves; calibrate the nominal BH curves of the objects to be tested using the same method as in S2 to obtain their standard BH curves; and extract the stress-sensitive magnetic parameters established in S2 from the calibrated standard BH curves of the objects to be tested.

[0025] S4. Compare the magnetic parameters extracted by S3 with the calibration relationship between the magnetic parameters and stress established by S2, and thereby quantitatively evaluate the load stress of the object to be measured.

[0026] The beneficial effects provided by the present invention are: it can effectively consider the influence of demagnetization effect and quantitatively characterize tensile stress through the true magnetic properties (magnetic characteristic parameters) of ferromagnetic materials; it is reliable and fast, easy to operate, not affected by the environmental magnetic field, and the measurement results are stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Shown is a schematic diagram of a standard closed-circuit magnetic measurement circuit and device;

[0028] Figure 2 Shown is a schematic diagram of an open-circuit force magnetic coupling measurement circuit and device;

[0029] Figure 1-Figure 2 middle:

[0030] 1—Excitation circuit; 11—Excitation power supply; 12—Excitation circuit resistor; 13—Excitation circuit voltmeter or other device capable of measuring voltage;

[0031] 2—Detection circuit; 21—Detection circuit resistance; 22—Detection circuit capacitance; 23—Detection circuit voltmeter or other device capable of measuring voltage; 3—Excitation coil; 4—Detection coil; 5—Standard closed-circuit sample; 6—Open-circuit measurement sample or object to be measured; 7—Stress;

[0032] Figure 3 It is the definition of magnetic characteristic parameters and the schematic diagram of demagnetization correction;

[0033] Figure 4 is the magnetic characteristic parameter H under different excitation intensities H0 max Schematic diagram of the characterization of tensile stress; Figure 5 is the magnetic characteristic parameter H under different excitation intensities H0 cj Schematic diagram of the characterization of tensile stress;

[0034] Figure 6 is the magnetic characteristic parameter p under different excitation intensities H0 h Schematic diagram of the characterization of tensile stress. DETAILED DESCRIPTION

[0035] 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.

[0036] The present invention provides a stress quantification magnetic measurement device and method based on demagnetization correction, please refer to Figure 1-Figure 2 , the device specifically includes:

[0037] Closed-circuit measurement unit and open-circuit measurement unit;

[0038] The closed-circuit measurement unit includes: a first basic measurement unit and a first test object; wherein the first basic measurement unit includes an excitation circuit 1, a detection circuit 2, an excitation coil 3 and a detection coil 4; the test object is a standard closed-circuit sample 5;

[0039] The open circuit measurement unit includes: a second basic measurement unit and a second test object; wherein the second basic measurement unit includes an excitation circuit 1, a detection circuit 2, an excitation coil 3 and a detection coil 4; the second test object is an open circuit measurement sample or an object to be measured 6;

[0040] The standard closed-circuit sample 5 is closed; the open-circuit measurement sample or the object to be measured 6 is open;

[0041] Except that the standard closed-circuit sample 5 of the closed-circuit measurement unit is different from the open-circuit measurement sample or the object to be measured 6 of the open-circuit measurement unit, the component parameters, connection mode, excitation parameters and detection parameters of the closed-circuit measurement unit and the first basic measurement unit and the second basic measurement unit of the open-circuit measurement unit are consistent;

[0042] The measurement results obtained by the closed-circuit measurement unit are used to perform demagnetization correction on the measurement results of the open-circuit measurement unit to obtain the true magnetic properties of the measured material;

[0043] The excitation circuit 1 and the detection circuit 2 are inductively connected via an excitation coil 3 and a detection coil 4 wound around a standard closed-circuit sample 5 and an open-circuit measurement sample or an object to be measured 6;

[0044] The excitation circuit 1 provides an alternating external magnetic field H0 with a fixed frequency to the sample, and is composed of an excitation power supply 11, an excitation circuit resistor 12, and an excitation circuit voltmeter or other device capable of measuring voltage 13;

[0045] The detection circuit 2 is used to collect the magnetic flux density change signal inside the sample, and is composed of a detection circuit resistor 21, a detection circuit capacitor 21 and a detection circuit voltmeter or other device 23 that can measure voltage.

[0046] The measurement results obtained by the closed-circuit measurement unit are used to perform demagnetization correction on the measurement results of the open-circuit measurement unit to obtain the true magnetic properties of the measured material.

[0047] The excitation circuit 1 provides the sample with an alternating external magnetic field H0 with a fixed frequency, and is composed of an excitation power supply 11, an excitation circuit resistor 12, and an excitation circuit voltmeter or other device that can measure voltage 13; the detection circuit 2 is used to collect the magnetic flux density change signal inside the sample, and is composed of a detection circuit resistor 21, a detection circuit capacitor 21, and a detection circuit voltmeter or other device that can measure voltage 23.

[0048] The excitation circuit 1 and the detection circuit 2 are inductively connected via an excitation coil 3 and a detection coil 4 wound around a standard closed-circuit sample 5;

[0049] The detection coil 4 is pre-wound on the surface of the standard closed-circuit sample 5, and the two are kept in close contact; then the excitation coil 3 is wound to cover the detection coil 4, such as Figure 1 shown.

[0050] It should be noted that if Figure 1 As shown, during a standard closed-circuit magnetic measurement, the excitation power supply 11 is first energized, and then the frequency or amplitude of the excitation power supply 11 is varied to achieve a change in the excitation intensity H0. The excitation signal and detection signal are then synchronously collected using an excitation circuit voltmeter or other voltage-measuring device 13 and a detection circuit voltmeter or other voltage-measuring device 23, respectively, to obtain the true magnetic properties of the sample, i.e., the true BH curve.

[0051] Please refer to Figure 2 , carry out open circuit force magnetic coupling measurement.

[0052] First, clamp the two ends of the open-circuit measurement sample or the object to be measured 6 in the tensile machine fixture to achieve stress loading, and then power on the excitation power supply 11. When the stress is loaded to the predetermined value, change the frequency or amplitude of the excitation power supply 11 to achieve the change of the excitation intensity H0, and synchronously collect the excitation signal and the detection signal through the excitation circuit voltmeter or other device that can measure voltage 13 and the detection circuit voltmeter or other device that can measure voltage 23. After the signal acquisition is completed, the stress of the open-circuit measurement sample is loaded to the next predetermined value and the above steps are repeated to obtain the nominal BH curve under different stresses. The nominal BH curve here mainly refers to the Figure 2 The measurement result of the device is affected by the demagnetization field and cannot reflect the true magnetic properties of the material.

[0053] like Figure 3 As shown, based on Figure 1 The results of standard closed-circuit magnetic measurements are Figure 2 The results of the open-circuit force magnetic coupling measurement are demagnetized. The measurement results of the open-circuit measurement sample or object 6 after demagnetization correction are close to the true magnetic properties of the material to a high degree.

[0054] like Figure 3 As shown, the magnetic characteristic parameters and the maximum magnetic field intensity H are defined on the real BH curve after demagnetization correction. max , intrinsic coercive field H cj and hysteresis loss power p h .

[0055] right Figure 3 The relevant instructions are as follows:

[0056] Basic magnetization curve - the line connecting the points where the magnetic induction intensity is the maximum;

[0057] H0—the abscissa of the basic magnetization curve (i.e., the excitation intensity);

[0058] H max —The maximum value of the external magnetic field intensity in the hysteresis loop;

[0059] H cj —Intrinsic coercive field, the horizontal coordinate corresponding to the magnetic induction intensity of 0;

[0060] p h —Hysteresis loss power, the product of the hysteresis loop area and the excitation frequency.

[0061] Under different stresses, these magnetic characteristic parameters will change significantly, which is the specific effect of pure stress on the true magnetic properties of the sample. In other words, the device provided by the present invention can accurately measure the true value of the magnetic characteristic parameters. Therefore, by applying the maximum external magnetic field strength H max , intrinsic coercive field Hcj and hysteresis loss power p h These parameters are stable and practical in quantitatively characterizing stress.

[0062] For an open-circuit measurement sample or object 6, the excitation coil 3 and detection coil 4 can be pre-wound around the sample or pre-wound using a geometric mold, and then the sample is inserted into the detection coil 4. The open-circuit measurement sample or object 6, the excitation coil 3, and the detection coil 4 remain coaxial. The open-circuit measurement sample or object 6 can be extended to a certain length to be gripped by the tensile machine clamp for stress loading.

[0063] It should be noted that the standard closed-circuit sample 5 and the open-circuit measurement sample or the object to be measured 6 can be any ferromagnetic material and have a certain electrical conductivity, but both need to be made of the same material type.

[0064] A stress quantification magnetic measurement method based on demagnetization correction is applied to a stress quantification magnetic measurement device based on demagnetization correction. The method comprises the following steps:

[0065] S1. Using the closed-circuit measurement unit, test a standard closed-circuit measurement sample to obtain a standard BH curve of the sample material.

[0066] It should be noted that the standard BH curve measurement process described in step S1 includes:

[0067] I. The standard closed-circuit sample 5 is pre-wound with the excitation coil 3 and the detection coil 4; the excitation coil 3 and the detection coil 4 are connected to the excitation circuit 1 and the detection circuit 2 respectively;

[0068] II. The excitation power supply 11 is first powered on, and then the frequency or amplitude of the excitation power supply 11 is changed to achieve a change in the excitation intensity H0; then, the excitation signal and the detection signal are synchronously collected through the excitation circuit voltmeter or other voltage-measuring device 13 and the detection circuit voltmeter or other voltage-measuring device 23, respectively, to obtain the standard BH curve of the standard closed-circuit sample 5.

[0069] S2. Using the above-mentioned open-circuit measurement unit (or an open-circuit measurement unit optimized therefrom), test open-circuit samples without stress and loaded with a series of stresses to obtain their nominal BH curves; using the standard BH curve obtained in S1, calibrate the nominal BH curve of the open-circuit sample to obtain its standard BH curve; extract the stress-sensitive magnetic parameters in the calibrated standard BH curve, and establish a relationship between the magnetic parameters and the known stress, which is the calibration relationship between the magnetic parameters and stress of the sample material;

[0070] The stress-sensitive magnetic parameters described in step S2 specifically include: the maximum value of the applied magnetic field intensity H max, intrinsic coercive field H cj and hysteresis loss power p h .

[0071] S3. Using the same open-circuit measurement unit as in S2, test the stress-free and possibly stressed objects to obtain their nominal BH curves; calibrate the nominal BH curves of the objects to be tested using the same method as in S2 to obtain their standard BH curves; and extract the stress-sensitive magnetic parameters established in S2 from the calibrated standard BH curves of the objects to be tested.

[0072] The method for correcting the nominal BH curve described in steps S2 and S3 includes the following steps:

[0073] S21. Using the above-mentioned open-circuit measurement unit (or an optimized open-circuit measurement unit thereof), test the stress-free open-circuit measurement sample or the object to be measured 6 to obtain a nominal BH curve of the open-circuit measurement sample or the object to be measured 6;

[0074] S22. Based on the correlation between the nominal BH curve and the standard BH curve, calculate the correlation parameter between the nominal BH curve in S21 and the standard BH curve in S1: demagnetization field parameter N f and coefficient parameter k m ;

[0075] In step S22, the correlation relationship and correlation parameters between the nominal BH curve and the standard BH curve are obtained through the following process:

[0076] I. Open circuit measurement: Multiply the nominal MH curve of the sample or object under load by the correction factor k. m , and obtain the true magnetization intensity M* of the sample after correction, as shown in Formula 1:

[0077] M * = k m M (1)

[0078] The conversion relationship between the MH curve and the BH curve is as follows: B = μ0 (H + M);

[0079] II. Correction coefficient k m , including open circuit measurement of the sample or object to be measured 6 k m1 and k of the object to be tested m2 , the nominal MH curve M measured by the open circuit measurement sample or the object to be measured 6 when there is no stress 名义-无应力 and the standard MH curve M measured by S1 标准 Obtain:

[0080] k m =M 标准 / M名义-无应力 (2)

[0081] III. Open circuit measurement of the magnetization intensity M of the sample or object 6 after correction * Multiply by the demagnetization factor N f That is the reverse additional demagnetization field;

[0082] The external magnetic field strength H of the open circuit measurement sample or the object to be measured 6 is added with the reverse additional demagnetization field -N f M * , as shown in formula (3):

[0083] H * = H - N f M * (3)

[0084] IV. Demagnetization parameter N f , including open circuit measurement of the sample or object to be measured 6 N f1 and N of the object to be measured f2 , obtained from the nominal MH curve of the open-circuit measurement sample or the object to be measured 6 without stress and the standard MH curve measured by S1:

[0085] N f =-(H 标准 -H 无应力 ) / M 标准 (4).

[0086] S23, using the open-circuit measurement unit and measurement parameters in S21, testing the open-circuit measurement sample or the object to be measured 6 loaded with stress to obtain nominal BH curves loaded with different stresses;

[0087] S24, using the demagnetization field parameter N obtained in S22 f and coefficient parameter k m , using the same correlation relationship in S22, the nominal BH curve of S23 loaded with different stresses is corrected to obtain the corrected standard BH curve of the loading series stress.

[0088] S4. Compare the magnetic parameters extracted by S3 with the calibration relationship between the magnetic parameters and stress established by S2, and thereby quantitatively evaluate the load stress of the object to be measured.

[0089] An improved solution is to optimize the device. The optimized detection device specifically optimizes the open circuit measurement unit as follows:

[0090] The excitation coil 3 and the detection coil 4 of the open circuit measurement unit may or may not be wound around the open circuit detection sample or the object to be measured 6; the components of the first basic measurement unit of the open circuit measurement unit and its connection method, device parameters, excitation parameters and detection parameters are consistent with the second basic measurement unit of the closed circuit measurement unit. Finally, the excitation coil 3 and the detection coil 4 of the open circuit measurement unit may or may not be wound around the open circuit detection sample or the object to be measured 6; the components of the first basic measurement unit of the open circuit measurement unit and its connection method, device parameters, excitation parameters and detection parameters are consistent with the second basic measurement unit of the closed circuit measurement unit.

[0091] In summary, the present invention is based on the principle of magnetomechanical coupling effect, and comprehensively considers the problems that standard closed-circuit samples cannot be mechanically loaded and open-circuit measurement samples are seriously affected by the demagnetization field. Figure 1 The results are demagnetized to make the open circuit force magnetic coupling measurement (as shown) Figure 2 The results are close to the real magnetic properties of the material to a high degree (as shown in Figure 3 After obtaining the true magnetic characteristic parameters of the material, a magnetic measuring device and a measuring method thereof are provided for quantitatively characterizing stress (as shown in FIG. Figures 4 to 6 shown).

[0092] In addition, the results measured by the device of the present invention, such as Figures 4 to 6 As shown in Figure 3, it shows the effect of tensile stress on the true magnetic properties of ferromagnetic materials, which reflects the inherent material properties of ferromagnetic materials.

[0093] The present invention provides a practical and feasible technical solution for experimental research on the magnetomechanical coupling effect of ferromagnetic materials. This solution is reliable, rapid, easy to operate, unaffected by ambient magnetic fields, produces stable measurement results, and effectively accounts for demagnetization effects. The present invention can be widely applied in numerous engineering applications, such as monitoring stress changes in cables of suspension and cable-stayed bridges, oil and gas drilling pipes, and critical steel structures.

[0094] 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 stress quantification magnetic measurement device based on demagnetization correction, characterized by: include: Closed-circuit measurement unit and open-circuit measurement unit; The closed-circuit measurement unit comprises: a first basic measurement unit and a first test object; wherein the first basic measurement unit comprises an excitation circuit (1), a detection circuit (2), an excitation coil (3) and a detection coil (4); and the test object is a standard closed-circuit sample (5); The open circuit measurement unit comprises: a second basic measurement unit and a second test object; wherein the second basic measurement unit comprises an excitation circuit (1), a detection circuit (2), an excitation coil (3) and a detection coil (4); and the second test object is an open circuit measurement sample or an object to be measured (6); The standard closed-circuit sample (5) is of a closed type; the open-circuit measurement sample or the object to be measured (6) is of an open type; Except that the standard closed-circuit sample (5) of the closed-circuit measurement unit is different from the open-circuit measurement sample or the object to be measured (6) of the open-circuit measurement unit, the first basic measurement unit of the closed-circuit measurement unit and the second basic measurement unit of the open-circuit measurement unit have the same component parameters, connection mode, excitation parameters and detection parameters; The measurement results obtained by the closed-circuit measurement unit are used to perform demagnetization correction on the measurement results of the open-circuit measurement unit to obtain the true magnetic properties of the measured material; The excitation circuit (1) and the detection circuit (2) are inductively connected via an excitation coil (3) and a detection coil (4) wound around a standard closed-circuit sample (5); The excitation circuit (1) and the detection circuit (2) are inductively connected via an excitation coil (3) and a detection coil (4) that are wound around or not wound around an open-circuit measurement sample or an object to be measured (6); the excitation circuit (1) provides an alternating external magnetic field H0 with a fixed frequency to the sample, and is composed of an excitation power supply (11), an excitation circuit resistor (12), and an excitation circuit voltmeter or other device capable of measuring voltage (13); The detection circuit (2) is used to collect the signal of the change in magnetic flux density inside the sample, and is composed of a detection circuit resistor (21), a detection circuit capacitor (22), and a detection circuit voltmeter or other device capable of measuring voltage (23).

2. The stress quantification magnetic measurement device based on demagnetization correction according to claim 1, characterized in that: A closed-circuit measurement unit is used to measure a standard closed-circuit sample (5), and an open-circuit measurement unit is used to measure an open-circuit measurement sample or an object to be measured (6); wherein the open-circuit measurement sample is loaded with a known stress, and the object to be measured may be loaded with an unknown stress.

3. The stress quantification magnetic measurement device based on demagnetization correction according to claim 1, characterized in that: The standard closed-circuit sample (5) and the open-circuit measurement sample or the object to be measured (6) are made of the same ferromagnetic material.

4. A stress quantification magnetic measurement method based on demagnetization correction, applied to a stress quantification magnetic measurement device based on demagnetization correction as claimed in any one of claims 1 to 3, characterized in that: The method comprises the following steps: S1. Using the closed-circuit measurement unit, test a standard closed-circuit measurement sample to obtain a standard BH curve of the sample material. S2. Using the open-circuit measurement unit, test open-circuit samples without stress and loaded with a series of known stresses to obtain their nominal BH curves; using the standard BH curve obtained in S1, calibrate the nominal BH curve of the open-circuit sample to obtain its standard BH curve; extract the stress-sensitive magnetic parameters in the calibrated standard BH curve and establish their relationship with the known stresses, which is the calibration relationship between the magnetic parameters and stress of the sample material; S3. Using the same open-circuit measurement unit as in S2, test the stress-free and possibly stressed objects to obtain their nominal BH curves; calibrate the nominal BH curves of the objects to be tested using the same method as in S2 to obtain their standard BH curves; and extract the stress-sensitive magnetic parameters established in S2 from the calibrated standard BH curves of the objects to be tested. S4. Compare the magnetic parameters extracted by S3 with the calibration relationship between the magnetic parameters and stress established by S2, and thereby quantitatively evaluate the load stress of the object to be measured.

5. The stress quantification magnetic measurement method based on demagnetization correction according to claim 4, characterized in that: The method for correcting the nominal BH curve described in steps S2 and S3 includes the following steps: S21, using the above-mentioned open circuit measurement unit to test the stress-free open circuit measurement sample or the object to be measured (6), and obtain the nominal BH curve of the open circuit measurement sample or the object to be measured (6); S22. Based on the correlation between the nominal BH curve and the standard BH curve, calculate the correlation parameter between the nominal BH curve in S21 and the standard BH curve in S1: demagnetization field parameter N f and coefficient parameter k m ; S23, using the open circuit measurement unit and measurement parameters in S21, testing the open circuit measurement sample or the object to be measured (6) loaded with stress to obtain the nominal BH curves loaded with different stresses; S24, using the demagnetization field parameter N obtained in S22 f and coefficient parameter k m , using the same correlation relationship as in S22, the nominal BH curve of S23 loaded with different stresses is corrected to obtain the corrected standard BH curve of the loading series stress.

6. The stress quantification magnetic measurement method based on demagnetization correction according to claim 4, characterized in that: The stress-sensitive magnetic parameters described in step S2 specifically include: the maximum value of the applied magnetic field intensity H max , intrinsic coercive field H cj and hysteresis loss power p h .

7. The stress quantification magnetic measurement method based on demagnetization correction according to claim 4, characterized in that: The standard BH curve measurement process described in step S1 includes: I. The standard closed-circuit sample (5) is pre-wound with an excitation coil (3) and a detection coil (4); the excitation coil (3) and the detection coil (4) are connected to an excitation circuit (1) and a detection circuit (2) respectively; II. The excitation power supply (11) is first powered on, and then the frequency or amplitude of the excitation power supply (11) is changed to achieve a change in the excitation intensity H0; then, the excitation signal and the detection signal are synchronously collected by the excitation circuit voltmeter or other device capable of measuring voltage (13) and the detection circuit voltmeter or other device capable of measuring voltage (23), respectively, to obtain a standard BH curve of the standard closed-circuit sample (5).

8. The stress quantification magnetic measurement method based on demagnetization correction according to claim 4, characterized in that: The nominal BH curve measurement process described in steps S2 and S3 includes: I. An open-circuit measurement sample in S2 that is stress-free or loaded with a series of known stresses, or an object to be measured in S3 that is stress-free or may be loaded with unknown stresses, is pre-wound with an excitation coil (3) and a detection coil (4); the excitation coil (3) and the detection coil (4) are connected to an excitation circuit (1) and a detection circuit (2), respectively; II. The excitation power supply (11) is powered on and the frequency or amplitude of the excitation power supply (11) is changed to achieve a change in the excitation intensity H0. The excitation signal and the detection signal are synchronously collected by the excitation circuit voltmeter or other device capable of measuring voltage (13) and the detection circuit voltmeter or other device capable of measuring voltage (23), respectively, to obtain a nominal BH curve of the open circuit measurement sample or the object to be measured (6).

9. The stress quantification magnetic measurement method based on demagnetization correction according to claim 5, characterized in that: In step S22, the correlation relationship and correlation parameters between the nominal BH curve and the standard BH curve are obtained through the following process: I. Open circuit measurement of the sample or object to be measured (6) The nominal MH curve under load conditions is multiplied by the coefficient parameter k m , and obtain the true magnetization intensity M* of the sample after correction, as shown in formula (1): M * = k m M (1) The conversion relationship between the MH curve and the BH curve is as follows: B = μ0 (H + M); II. Coefficient parameter k m , including open circuit measurement of the sample or object to be measured (6) m1 and k of the object to be tested m2 , the nominal MH curve M measured by the open circuit measurement sample or the object to be measured (6) when no stress is measured and the standard MH curve M measured by S1 标准 Obtain: k m =M 标准 / M 名义-无应力 (2) III. Open circuit measurement of the sample or object to be measured (6) The corrected magnetization intensity M * Multiply by the demagnetization field parameter N f That is the reverse additional demagnetization field; The external magnetic field strength H of the open circuit measurement sample or the object to be measured (6) is added with the reverse additional demagnetization field -N f M * , as shown in formula (3): H * = H - N f M * (3) IV. Demagnetization parameter N f , including N of the open circuit measurement sample or object to be measured (6) f1 and N of the object to be measured f2 , obtained from the nominal MH curve of the open-circuit measurement sample or the object to be measured (6) in the stress-free state and the standard MH curve measured by S1: N f =-(H 标准 -H 无应力 ) / M 标准 (4)。

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