A magnetic measurement method for plane vector stress

Abstract

This invention provides a magnetic measurement method for planar vector stress, relating to the field of stress testing technology for iron-based materials. The method includes: obtaining the principal stress difference between the maximum and minimum principal stresses of the iron-based specimen; obtaining the principal stress sum of the maximum and minimum principal stresses of the iron-based specimen; and combining the principal stress difference and the principal stress sum to obtain the maximum and minimum principal stresses. This invention can directly obtain the precise values ​​of the maximum and minimum principal stresses, as well as the directions of the principal stresses, avoiding subsequent calculation errors and cumulative errors. It solves the problem that existing calculation methods can only determine the principal stress direction angle and the principal stress difference.

Description

Technical Field

[0001] This invention relates to the field of stress testing technology for iron-based materials, and more particularly to a magnetic method for measuring planar vector stress. Background Technology

[0002] To minimize energy during the spontaneous magnetization equilibrium distribution, iron-based materials develop magnetic domains. A magnetic domain is defined as a small region within an iron-based material where the spontaneous magnetization orientation of each atom is identical. Under a magnetic field, domains with different orientations exhibit varying degrees of magnetization difficulty, a phenomenon known as magnetocrystalline anisotropy. The process by which an iron-based material, under the influence of an applied magnetic field, transitions from a magnetically neutral state to a magnetically saturated state where all magnetic moments align with the applied magnetic field direction is called magnetization. Applying stress to an iron matrix causes deformation, which, through magnetoelasticity, preferentially orients magnetic moments, leading to stress anisotropy. Similar to magnetic anisotropy, stress anisotropy also hinders magnetization. For iron-based materials with a magnetostriction coefficient greater than zero, permeability increases in the direction of tensile stress and decreases in the direction of compressive stress. This results in magnetic anisotropy. The magnitude of permeability varies with the magnitude of stress, and the principal permeability aligns with the principal stress direction. The permeability μ varies with the angle θ due to the anisotropy of stress. Therefore, the magnitude and direction of the principal stress can be obtained by measuring the changes in permeability in various directions at a point in the material.

[0003] The magnetic stress measurement method of the diode probe stress detector utilizes the interrelationship between circuits, magnetic fields, and stress. The effect of stress on the magnetic field is expressed by circuit parameters. Stress changes the total magnetic reluctance in the magnetic circuit, which in turn changes the magnetic flux of the entire magnetic circuit, resulting in a change in the voltage across the coil. The stress change value can be deduced by detecting the current across the measuring resistor in the bridge circuit. Wang Zhenshan et al. from Xi'an Jiaotong University studied the relationship between the output of the diode magnetic sensor and the principal stress and the measurement angle, proposing that the difference in magnetic measurement signal current along the two directions, I2-I1, has an approximately single-valued linear relationship with the principal stress difference (σ1-σ2). Li Siyuan derived the relationship expression between the principal stress sum, the principal stress difference, and the output in the principal stress direction, and established a formula for calculating residual stress. R. Langman improved a new type of sensor by placing two orthogonal induction coils on the surface of the material being measured between the two magnetic poles using a two-pole excitation source. When a material is under stress, due to magnetic anisotropy, the direction of the magnetization intensity of the material will deflect under the action of an external excitation magnetic field, and the output signals of the two induction coils will change. The difference in principal stress can be evaluated by the ratio of the two output signals.

[0004] Existing calculation methods can only solve for the principal stress difference and principal stress direction angle. To obtain the absolute values ​​of the maximum and minimum principal stresses, other more complex derivation formulas are required, which introduces a significant cumulative error, resulting in a large error in the obtained stress values. Summary of the Invention

[0005] To address the technical problem that existing calculation methods can only determine the principal stress direction angle and principal stress difference, a magnetic measurement method for planar vector stress is provided.

[0006] The technical means employed in this invention are as follows:

[0007] A magnetic measurement method for planar vector stress includes the following steps:

[0008] Obtain the principal stress difference between the maximum and minimum principal stresses of the iron-based specimen;

[0009] Obtain the sum of the principal stresses of the maximum and minimum principal stresses of the iron-based specimen;

[0010] By combining the principal stress difference with the principal stress sum, we obtain the maximum principal stress and the minimum principal stress.

[0011] Furthermore, obtaining the principal stress difference between the maximum and minimum principal stresses of the iron-based specimen includes:

[0012] Obtain the principal stress direction angles of the iron-based specimen;

[0013] Obtain the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit;

[0014] Based on the principal stress direction angle, the unbalanced current value of the 0° bridge circuit and the unbalanced current value of the 90° bridge circuit, the difference between the maximum principal stress direction current output value and the minimum principal stress direction current output value is obtained.

[0015] The difference between the maximum and minimum principal stresses is obtained by comparing the current output values ​​in the direction of maximum and minimum principal stress.

[0016] Furthermore, the principal stress difference between the maximum principal stress and the minimum principal stress satisfies the following formula:

[0017]

[0018] in,

[0019] (I2-I1)=K1(σ1-σ2);

[0020]

[0021] In the formula: σ1 is the maximum principal stress / MPa; σ2 is the minimum principal stress / MPa; I1 is the current output value in the direction of maximum principal stress / mA; I2 is the current output value in the direction of minimum principal stress / mA; K1 is the sensitivity coefficient / mA·MPa -1 ;I 0° The unbalanced current value of the 0° bridge circuit is given in mA; I 90° θ is the unbalanced current value of the 90° bridge circuit / mA; θ is the angle between the direction of the maximum principal stress and the X-axis / degrees.

[0022] Furthermore, when the direction of the principal stress is unknown, the direction angle of the principal stress satisfies the following formula:

[0023]

[0024] In the formula: θ is the angle (in degrees) between the direction of the maximum principal stress and the X-axis; I 0° I 45° I 90° The unbalanced current values ​​of the bridge circuit in the three directions of 0°, 45° and 90° are respectively in mA.

[0025] Furthermore, the sensitivity coefficient K1 is determined by a uniaxial tensile calibration test and satisfies the following formula:

[0026]

[0027] Where: K 1i is the stress difference sensitivity coefficient; n is the number of loading cycles.

[0028] Furthermore, the sum of the principal stresses for obtaining the maximum and minimum principal stresses of the iron-based specimen includes:

[0029] Obtain the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit, and then obtain the sum of the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit.

[0030] Based on the sum of the unbalanced current values ​​of the 0° and 90° bridge circuits, the sum of the principal stresses of the maximum and minimum principal stresses is obtained.

[0031] Furthermore, the principal stresses satisfy the following formula:

[0032]

[0033] In the formula: σ1 is the maximum principal stress / MPa; σ2 is the minimum principal stress / MPa; K2 is the sensitivity coefficient / mA·MPa -1 ;I 0° I 90° The unbalanced current values ​​of the bridge circuit in the 0° and 90° directions are respectively (mA).

[0034] Furthermore, the sensitivity coefficient K2 is determined by a uniaxial tensile calibration test and satisfies the following formula:

[0035]

[0036] Where: K 2i denoted as stress and sensitivity coefficient; n represents the number of loading cycles.

[0037] Furthermore, the maximum principal stress and the minimum principal stress satisfy the following formula:

[0038]

[0039] In the formula: σ1 is the maximum principal stress / MPa; σ2 is the minimum principal stress / MPa; K1 is the sensitivity coefficient / mA·MPa -1 K2 is the sensitivity coefficient / mA·Mpa -1 ;I 0° The unbalanced current value of the 0° bridge circuit is given in mA; I 90° θ is the unbalanced current value of the 90° bridge circuit / mA; θ is the angle between the direction of the maximum principal stress and the X-axis / degrees.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] This invention provides a magnetic measurement method for planar vector stress, and proposes an improved stress algorithm for a two-stage stress meter based on the magnetic anisotropy method. This method is combined with the original calculation method, thereby directly obtaining the precise values ​​of the maximum and minimum principal stresses and the direction of the principal stresses without going through tedious and lengthy subsequent calculation steps. This avoids subsequent calculation errors and cumulative errors, thus solving the problem that existing calculation methods can only determine the principal stress direction angle and the principal stress difference.

[0042] Based on the above reasons, this invention can be widely applied in fields such as stress testing. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a diagram of the sensor device for the second-level stress measuring instrument based on the magnetic anisotropy method of the present invention.

[0045] Figure 2 This is the calibration curve of the sensor (probe) of the diode stress measuring instrument of the present invention. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0050] Example 1

[0051] Existing calculation methods can only solve for the principal stress difference and principal stress direction angle. To obtain the absolute values ​​of the maximum and minimum principal stresses, more complex derivation formulas are required, leading to significant cumulative errors and substantial inaccuracies in the obtained stress values. This invention provides a magnetic measurement method for plane vector stress, based on a novel relationship between principal stress and current. By combining this method with existing calculation methods in this field, plane vector stress can be solved. The new algorithm eliminates the need for complex subsequent calculations and additional stress measurement steps, offering advantages in simplicity and accuracy. This invention can quickly solve for the maximum and minimum principal stresses and principal stress direction angles, and is particularly suitable for secondary sensor probes based on the magnetic anisotropy method for stress measurement. The obtained measurement data can be directly used in calculations, making it suitable for rapid assessment and calculation of stress distribution.

[0052] The present invention provides a magnetic measurement method for planar vector stress, proposing a novel calculation method that transforms the original calculation method, which only yields the stress difference and principal stress direction, into a method that, by combining the novel calculation method with the original method, can solve for the precise values ​​of the maximum principal stress, the minimum principal stress, and the principal stress direction angle.

[0053] The calculation method of this invention has a well-established theoretical connection with the original calculation method. That is, in the original calculation method, the principal stress difference and the current difference in the two directions have an approximately single-valued linear relationship; in the newly proposed calculation method, the principal stress sum and the current sum in the two directions also have an approximately single-valued linear relationship.

[0054] The coefficients K1 and K2 in the single-valued linear relationship in the original calculation method and the single-valued linear relationship in the newly proposed calculation method of this invention can both be calibrated through the same calibration experiment.

[0055] After the coefficients K1 and K2 are simultaneously calibrated under tension, the original measurement steps can still be followed when measuring stress. There is no need to add new measurement steps. After calibration, the stress data is measured. Similar to the original calculation method, the original calculation method and the newly proposed calculation method can be combined and simplified. Then, the data only needs to be substituted into the simplified formula to solve for the precise values ​​of the maximum principal stress, the minimum principal stress, and the principal stress direction angle.

[0056] I. Analysis and Summarization of the Original Calculation Method

[0057] As attached Figure 1This diagram shows the sensor device of a two-stage stress measuring instrument based on the magnetic anisotropy method. A closed loop is formed by a magnetic core I, a coil II, and an iron-based specimen III. An excitation current, passing through the excitation coil, generates an alternating magnetic field. This magnetic field is emitted into the iron-based specimen for stress detection. The feedback magnetic signal is then recovered by the detection coil and converted into a detection current through electromagnetic induction. Based on the relationship between stress and the magnetic and electrical signals, the internal stress distribution of the specimen is deduced, thus achieving the purpose of stress detection in the iron-based specimen. For two-stage probe equipment measuring surface stress, extensive theoretical analysis and experimental research have proven that the principal stress difference and the current difference in the two directions have an approximately single-valued linear relationship, expressed as:

[0058] (I2-I1)=K1(σ1-σ2) (1)

[0059] In the formula: I1 is the current output value in the direction of maximum principal stress / mA; I2 is the current output value in the direction of minimum principal stress / mA; K1 is the sensitivity coefficient / mA·MPa -1 σ1 is the maximum principal stress / MPa; σ2 is the minimum principal stress / MPa.

[0060] When the direction of the principal stress is unknown, the direction angle of the principal stress can be determined using the following formula:

[0061]

[0062] In the formula: θ is the angle (in degrees) between the direction of the maximum principal stress and the X-axis; I 0° I 45° I 90° The unbalanced current values ​​of the bridge circuit in the three directions of 0°, 45° and 90° are respectively in mA.

[0063] The maximum principal stress direction current output value I1, the minimum principal stress direction current output value I2, and the 0° bridge unbalanced current value I 0° 90° bridge unbalanced current value I 90° The following relationship exists between them:

[0064]

[0065] Therefore, by combining formula (1) and formula (3), we can obtain:

[0066]

[0067] The original calculation method ends here. It can be seen that the original calculation formula only yields the stress difference value, which cannot intuitively reflect the maximum principal stress value and the minimum principal stress value. If we want to continue to solve, we need to use the shear stress difference method. The shear stress difference method formula is complicated and has a cumulative error that cannot be ignored, which undoubtedly affects the calculation accuracy and calculation difficulty.

[0068] II. Proposal of New Calculation Methods

[0069] Existing calculation methods cannot directly obtain the magnitudes of the maximum and minimum principal stresses in a plane; they can only provide the difference in principal stresses and their directions. This invention, by exploring the relationship between the sum of principal stresses and the sum of currents, and then combining this with existing calculation methods, transforms the formula into a single equation, thereby obtaining the values ​​of the maximum and minimum principal stresses.

[0070] According to the Mohr's circle of stress, at any point in a plane, the sum of the normal stresses in any two mutually perpendicular directions is equal. That is:

[0071] σ1+σ2=σ 0° +σ 90° (5)

[0072] After single-point stress measurement, the experimental results show that the relationship between the principal stress and the current approximately satisfies the following relationship:

[0073] I 90° +I 0° =K2(σ1+σ2) (6)

[0074] In the formula: K2 is the sensitivity coefficient / mA·MPa -1 ;I 0° I 90° The values ​​are: unbalanced current in the bridge circuit at 0° and 90° (mA); σ1 is the maximum principal stress (MPa); and σ2 is the minimum principal stress (MPa).

[0075] The sensitivity coefficient K2 in the formula can be calibrated by the same tensile calibration experiment as K1.

[0076] ① By transforming formula (6), we can obtain:

[0077]

[0078] ② Combining formula (4) with formula (7), we get:

[0079]

[0080] ③Simplifying the above equation, we get:

[0081]

[0082] When the direction of the principal stress is unknown, the principal stress direction angle can still be determined using formula (2):

[0083]

[0084] Thus, the new calculation method of this invention has been derived through the inductive summary in step one and the simultaneous simplification in step two. Using this calculation method, the final result can be obtained directly from the experimental data without the need for further calculations, thus avoiding accumulated errors.

[0085] The newly proposed calculation method can solve the problem that the original calculation method cannot directly obtain the magnitude of the maximum and minimum principal stresses in the plane. By combining the new calculation method with the original calculation method, the specific values ​​of the maximum and minimum principal stresses in the plane can be obtained.

[0086] III. Calibration of sensitivity coefficients K1 and K2

[0087] Sensitivity coefficients K1 and K2 are determined by uniaxial tensile and compressive tests. Since both the calculation method proposed in this invention and the original calculation method use axial and perpendicular axial data from uniaxial tensile tests for their sensitivity coefficients, they can be calibrated simultaneously. This is one of the advantages of this invention, as it eliminates the need for additional tensile calibration steps and allows for simultaneous tensile calibration tests.

[0088] Define the stress difference as ΔI1=I 90° -I 0° The stress sum is ΔI² = I 90° +I 0° During unidirectional loading, the loading stress σ should have a linear relationship with ΔI1 and ΔI2, which can be represented by two approximate straight lines passing through the origin in the coordinate system. These two straight lines are called calibration curves, and their slopes are the sensitivity coefficients K1 and K2. When the loading stress is different, the relationship between stress and ΔI1 and ΔI2 is as follows:

[0089]

[0090] Where: K 1i K is the stress difference sensitivity coefficient. 2i For stress and sensitivity coefficients, σ i This represents the axial normal stress. Therefore, the expressions for the sensitivity coefficients K1 and K2 are determined.

[0091]

[0092] In the formula: n is the number of loading times.

[0093] Example 2

[0094] I. Summarize the relationship between principal stress and current.

[0095] As shown in Example 1, at the same point in a plane, the sum of the normal stresses in any two mutually perpendicular directions is equal. That is:

[0096] σ1+σ2=σ 0° +σ 90°(5)

[0097] According to the relationship mentioned in formula (5), the unknown direction σ1+σ2 and the known direction σ 0° +σ 90° They are equal, therefore I can be used 0° +I 90° Further calculations are performed to confirm the measured angle.

[0098] Therefore, a square steel plate with dimensions of 360mm × 360mm and a thickness of 10mm was used. The steel plate material was quenched 45 steel. The current values ​​at 0°, 45°, 90° and 135° directions were measured at a single point on the quenched steel plate.

[0099] The data obtained after measurement can be fitted to determine the relationship between the principal stress and the current. The experimental results approximately satisfy the following relationship:

[0100] I 90° +I 0° =K2(σ1+σ2) (6)

[0101] In the formula: K2 is the sensitivity coefficient / mA·MPa -1 ;I 0° I 90° The values ​​are: unbalanced current in the bridge circuit at 0° and 90° (mA); σ1 is the maximum principal stress (MPa); and σ2 is the minimum principal stress (MPa).

[0102] The sensitivity coefficient K2 in the formula can be calibrated by the same tensile calibration experiment as K1.

[0103] II. Proposal of New Calculation Methods

[0104] The specific process is as follows:

[0105] ① By transforming formula (6), we can obtain:

[0106]

[0107] ② Combining formula (4) with formula (7), we get:

[0108]

[0109] ③Simplifying the above equation, we get:

[0110]

[0111] When the direction of the principal stress is unknown, the principal stress direction angle can still be determined using formula (2):

[0112]

[0113] Thus, the new calculation method of this invention has been derived through the inductive summary in step one and the simultaneous simplification in step two. Using this calculation method, the final result can be obtained directly from the experimental data without the need for further calculations, thus avoiding accumulated errors.

[0114] III. Calibrate sensitivity coefficients K1 and K2

[0115] Define the stress difference as ΔI1=I 90° -I 0° The stress sum is ΔI² = I 90° +I 0° During unidirectional loading, the loading stress σ should have a linear relationship with ΔI1 and ΔI2, which can be represented by two approximate straight lines passing through the origin in the coordinate system. These two straight lines are called calibration curves, and their slopes are the sensitivity coefficients K1 and K2. When the loading stress is different, the relationship between stress and ΔI1 and ΔI2 is as follows:

[0116]

[0117] In the formula, K 1i K is the stress difference sensitivity coefficient. 2i For stress and sensitivity coefficients, σ i This represents the axial normal stress. Therefore, the expressions for the sensitivity coefficients K1 and K2 are determined.

[0118]

[0119] In the formula: n is the number of loading times.

[0120] A uniaxial tensile calibration test was conducted on the tensile specimens using a microcomputer-controlled hydraulic universal tensile testing machine. The measuring instrument was a diode probe stress magnetometer, and the specimen material was annealed 45# steel. The sensitivity coefficients K1 and K2 were determined to be 0.00105 mA / MPa and 0.00276 mA / MPa, respectively, through experimentation.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic measurement method for planar vector stress, characterized in that, Includes the following steps: Obtain the principal stress difference between the maximum and minimum principal stresses of the iron-based specimen; Obtain the sum of the principal stresses of the maximum and minimum principal stresses of the iron-based specimen; By combining the principal stress difference with the principal stress sum, we can obtain the maximum principal stress and the minimum principal stress. The sum of the principal stresses for obtaining the maximum and minimum principal stresses of iron-based specimens includes: Obtain the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit, and then obtain the sum of the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit. Based on the sum of the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit, the sum of the principal stresses of the maximum and minimum principal stresses is obtained. The principal stresses satisfy the following formula: ； In the formula: σ 1 represents the maximum principal stress in MPa; σ 2 represents the minimum principal stress in MPa; K 2 represents the sensitivity coefficient / mA Mpa -1 ; , The unbalanced current values ​​of the bridge circuit in the 0° and 90° directions are respectively (mA).

2. The magnetic measurement method for planar vector stress according to claim 1, characterized in that, The principal stress difference between the maximum and minimum principal stresses of iron-based specimens includes: Obtain the principal stress direction angles of the iron-based specimen; Obtain the unbalanced current values ​​of the 0° bridge circuit and the 90° bridge circuit; Based on the principal stress direction angle, the unbalanced current value of the 0° bridge circuit and the unbalanced current value of the 90° bridge circuit, the difference between the maximum principal stress direction current output value and the minimum principal stress direction current output value is obtained. The difference between the maximum and minimum principal stresses is obtained by comparing the current output values ​​in the direction of maximum and minimum principal stress.

3. The magnetic measurement method for planar vector stress according to claim 2, characterized in that, The difference between the maximum principal stress and the minimum principal stress satisfies the following formula: ； in, ； ； In the formula: σ 1 represents the maximum principal stress in MPa; σ 2 represents the minimum principal stress in MPa; I 1 represents the current output value in the direction of maximum principal stress, in mA. I 2 represents the current output value in the direction of minimum principal stress (mA); K 1 represents the sensitivity coefficient / mA Mpa -1 ; The unbalanced current value of the 0° bridge circuit is given in mA. The unbalanced current value of the 90° bridge circuit is given in mA. θ The angle (in degrees) between the direction of the maximum principal stress and the X-axis.

4. The magnetic measurement method for planar vector stress according to claim 2 or 3, characterized in that, When the direction of the principal stress is unknown, the direction angle of the principal stress satisfies the following formula: ； In the formula: θ The angle (in degrees) between the direction of the maximum principal stress and the X-axis; , , The unbalanced current values ​​of the bridge circuit in the three directions of 0°, 45° and 90° are respectively in mA.

5. The magnetic measurement method for planar vector stress according to claim 3, characterized in that, Sensitivity coefficient K 1. Determined by a uniaxial tensile calibration test, satisfying the following formula: ； In the formula: K 1i This is the stress difference sensitivity coefficient; n This represents the number of times the data was loaded.

6. The magnetic measurement method for planar vector stress according to claim 1, characterized in that, Sensitivity coefficient K 2. Determined by a uniaxial tensile calibration test, satisfying the following formula: ； In the formula: K 2i These are the stress and sensitivity coefficients; n This represents the number of times the data was loaded.

7. The magnetic measurement method for planar vector stress according to claim 1, characterized in that, The maximum principal stress and the minimum principal stress satisfy the following formula: ； In the formula: σ 1 represents the maximum principal stress in MPa; σ 2 represents the minimum principal stress in MPa; K 1 represents the sensitivity coefficient / mA Mpa -1 ; K 2 represents the sensitivity coefficient / mA Mpa -1 ; The unbalanced current value of the 0° bridge circuit is given in mA. The unbalanced current value of the 90° bridge circuit is given in mA. θ The angle (in degrees) between the direction of the maximum principal stress and the X-axis.

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