Permanent magnet steel magnetic performance degradation law prediction method based on magnetic viscosity

Abstract

The invention discloses a permanent magnet steel magnetic performance degradation law prediction method based on magnetic viscosity. The invention belongs to the technical field of permanent magnet steel, and particularly relates to a permanent magnet steel magnetic performance degradation law prediction method based on magnetic viscosity. The invention aims to solve the problem that the magnetic performance degradation rule of the magnetic steel cannot be accurately predicted in the prior art. The method comprises the following steps: carrying out a magnetic viscosity performance test on permanent magnet steel based on a vibration sample magnetometer to obtain a time-varying curve of magnetization intensity, a logarithmic relation curve of magnetization intensity and time and a relation curve of a magnetic viscosity coefficient and an external magnetic field; analyzing the influence of the demagnetizing field on the relationship between the total magnetic field and the external magnetic field in the magneto-viscous process, and obtaining the relationship data of the total magnetic field and the external magnetic field; constructing a magnetic performance degradation prediction model, and introducing temperature coefficient correction to obtain a relationship among magnetization intensity variation, storage time, an applied magnetic field, a demagnetization factor and initial magnetization intensity; and predicting the magnetic performance degradation law of the permanent magnet steel through the magnetic performance degradation amount prediction model.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet steels, and particularly relates to a method for predicting the degradation law of the magnetic properties of permanent magnet steels based on magnetic viscosity. Background Art

[0002] In the current booming development of modern technology, the progress of many cutting-edge technologies highly depends on the performance improvement of precision sensing and measurement devices. With its high precision, high stability, and excellent dynamic response characteristics, the quartz accelerometer has already become the core supporting technology in many key fields. In the aerospace field, the accurate navigation, attitude control, and precise monitoring of the flight trajectory of aircraft all rely on the accurate acceleration data provided by the quartz accelerometer. Its measurement accuracy directly determines whether the aircraft can perform tasks safely and stably, and plays a decisive role in the success or failure of flight missions. In the military and national defense field, whether it is the precise strike of precision-guided weapons or the underwater navigation and control of ships and submarines, the high-performance performance of the quartz accelerometer provides a solid guarantee for the combat effectiveness of military equipment and is a key link to ensure the high precision and reliability of military operations. In the field of industrial automation control, from the precision machining of high-end manufacturing to the precise handling of intelligent logistics systems, the quartz accelerometer helps industrial production achieve more efficient and precise automated operations, greatly improving production efficiency and product quality. In the field of inertial navigation, whether in an environment where global satellite navigation signals are interfered with or cannot be covered, or in special application scenarios with extremely high requirements for navigation accuracy, the quartz accelerometer, as the core component of the inertial navigation system, always provides stable and reliable acceleration information for the carrier to ensure that the navigation system can work continuously and accurately.

[0003] The permanent magnet steel, as the core magnetic component inside the quartz accelerometer, is like the engine to an automobile and is the key for the entire accelerometer to accurately sense acceleration changes. The quality and stability of its magnetic properties, just like the cornerstone to a high-rise building, directly determine the overall performance and reliability of the accelerometer. It can be said without exaggeration that the performance of the permanent magnet steel is the core factor determining whether the quartz accelerometer can exert its excellent effectiveness in the above key fields.

[0004] However, permanent magnets face many complex challenges in actual use environments, and it is difficult to maintain an ideal constant state. Among the many influencing factors, the external magnetic field is an extremely critical and complex variable. In actual application scenarios, permanent magnets are often in various complex magnetic field environments. External magnetic fields of different strengths and directions will be like invisible "big hands" that continue to "reshape" the magnetic domain structure inside the magnet. Over time, the magnetic domain structure gradually changes, and the originally orderly arranged magnetic domains become chaotic and disordered. This change in the magnetic domain structure at the microscopic level will have a significant impact on the macroscopic level like ripples, which is directly reflected in the fluctuation and attenuation of magnetic performance parameters. For example, the key magnetic performance parameter of magnetization intensity will gradually weaken with the action of the external magnetic field, resulting in a decrease in the sensitivity of the accelerometer to small acceleration changes; the coercive force will also change, which will reduce the ability of the magnet to resist external magnetic field interference, thereby affecting the measurement accuracy and stability of the accelerometer.

[0005] The shape factor of the magnet itself also plays an important role in the degradation of magnetic properties. Since the magnetic field distribution generated by magnets of different shapes in space has its own characteristics, the demagnetization field they are affected by is completely different when facing the same external conditions. Taking slender magnets and block magnets as examples, the slender magnets have a relatively dispersed magnetic field distribution in space due to their unique geometric structure, and the size and direction of the demagnetization field are significantly different from those of block magnets. This difference in demagnetization field will cause the degradation process and rate of magnetic properties of the two shapes of magnets to show significant inconsistency under the same external environment. Specifically, the magnetic domains of slender magnets may be more easily deflected and rearranged under the action of the demagnetization field, resulting in a relatively fast degradation of magnetic properties; while the demagnetization field is relatively small due to the relatively concentrated magnetic field distribution of block magnets, and the degradation rate of magnetic properties may be relatively slow.

[0006] Temperature changes play the role of "catalyst" in the degradation of the magnetic properties of permanent magnetic steel. In actual application scenarios, temperature changes are everywhere. Whether it is the seasonal fluctuations in natural ambient temperature or the local temperature increase caused by heat generated by various factors during the operation of the equipment, it will have a thermal activation effect on the permanent magnetic steel. This thermal activation effect is like injecting "vitality" into the magnetic domain, causing the magnetic domain to irreversibly reverse. At the same time, high temperature will also cause the saturation magnetization intensity of the magnetic steel to decrease, reducing the maximum magnetization degree that the magnetic steel can achieve. For example, in some high-temperature industrial environments, such as steel smelting, glass manufacturing and other industries, permanent magnetic steel is in a high temperature state for a long time, and the degradation rate of its magnetic properties will be significantly accelerated. This rapid degradation of magnetic properties will seriously affect the measurement accuracy and stability of the accelerometer, causing the accelerometer to produce large errors during the measurement process and unable to accurately reflect the actual acceleration changes.

[0007] However, in the current related technical fields, the existing research and technical means have obvious limitations. In most cases, researchers often only consider the influence of one or a few of these factors on the magnetic properties of permanent magnet steels in isolation. For example, some studies only focus on the influence of the applied magnetic field on the magnetic properties, while ignoring the effects of the shape of the magnet steel and temperature changes; some studies only consider the influence of temperature on the magnetic properties, without considering the combined effects of the applied magnetic field and the shape of the magnet steel. This one-sided research method results in the lack of an effective model that can comprehensively, systematically, and accurately consider various factors such as the applied magnetic field, the shape of the magnet steel, and temperature changes, and accurately predict the long-term degradation law of the magnetic properties of permanent magnet steels. This technical shortcoming has caused a series of problems in the design, production, use, and maintenance processes of quartz accelerometers. Due to the inability to accurately predict the changes in the magnetic properties of permanent magnet steels, in the design stage of the accelerometer, it is difficult for engineers to select the most suitable permanent magnet steel according to actual requirements, resulting in potential performance risks in the design scheme; in the production stage, due to the inability to effectively control the consistency of the magnetic properties of the magnet steel, the product quality may vary; during use, due to the inability to predict in advance the degradation of the magnetic properties of the magnet steel, the scale factor of the accelerometer may deviate, thereby affecting the accuracy of the entire measurement system; in the maintenance stage, due to the lack of an accurate magnetic property degradation prediction model, it is difficult to formulate a reasonable maintenance plan, resulting in increased maintenance costs and the inability to detect and solve problems caused by the degradation of the magnetic properties of the magnet steel in a timely manner. In some application scenarios with extremely high precision requirements, such as navigation and positioning, the measurement errors of the accelerometer caused by the degradation of the magnetic properties of the magnet steel may lead to serious consequences, such as the aircraft deviating from the predetermined route and the missile strike accuracy decreasing.

[0008] Based on this, the present invention proposes a method for predicting the degradation law of the magnetic properties of permanent magnet steels based on magnetic viscosity. Summary of the Invention

[0009] The object of the present invention is to solve the problem in the prior art that the degradation law of the magnetic properties of magnet steels cannot be accurately predicted, and further provide a method for predicting the degradation law of the magnetic properties of permanent magnet steels based on magnetic viscosity.

[0010] A method for predicting the degradation law of the magnetic properties of permanent magnet steels based on magnetic viscosity according to the present invention includes the following steps:

[0011] Step 1: Perform magnetic viscosity performance tests on the permanent magnet steel based on a vibrating sample magnetometer to obtain the magnetization intensity vs. time curve, the magnetization intensity vs. logarithm of time curve, and the magnetic viscosity coefficient vs. applied magnetic field curve;

[0012] Step 2: Analyze the influence of the demagnetizing field on the relationship between the total magnetic field and the applied magnetic field during the magnetic viscosity process, and obtain the relationship data between the total magnetic field and the applied magnetic field;

[0013] Step 3: Build a prediction model for the magnetic property degradation amount, introduce temperature coefficient correction, and obtain the relationship among the change amount of magnetization intensity, storage time, applied magnetic field, demagnetization factor, and initial magnetization intensity.

[0014] Step 4: Predict the magnetic property degradation law of the permanent magnet by using the prediction model for the magnetic property degradation amount.

[0015] The present invention has the following beneficial effects:

[0016] 1. Comprehensiveness and systematicness. For the first time, this model comprehensively considers various key factors such as applied magnetic field, magnet shape, and temperature change, breaking the limitations of previous studies that only focused on single or a few factors. This comprehensiveness makes the prediction of the magnetic property degradation law of the permanent magnet more in line with the actual application scenario, can more accurately reflect the performance change trend of the magnet under complex working conditions, and provides a more reliable basis for the performance evaluation of the accelerometer.

[0017] 2. High-precision prediction ability. By combining a large number of experimental tests and in-depth theoretical analysis, the constructed prediction model has extremely high precision in predicting the magnetic property degradation amount. Whether it is short-term or long-term magnetic property changes, they can be estimated with a small error. For example, in the prediction of the permanent magnet in a specific type of accelerometer, compared with the actual measurement data, the prediction error of the change amount of magnetization intensity can be controlled within a very small range, which is of great significance for applications in fields such as aerospace and military defense that require high precision, can effectively avoid measurement errors caused by magnetic property deviations, and improve the reliability and accuracy of the entire system.

[0018] 3. Wide adaptability. This model is applicable to permanent magnets with different shapes, different initial magnetization intensities, and in various applied magnetic field and temperature environments. Whether it is a common block magnet or a magnet with a special shape, whether it is in a normal temperature environment or extreme temperature environments such as high temperature and low temperature, this model can be used to effectively predict the magnetic property degradation. This greatly broadens its application scope. It can not only be applied to existing accelerometer products, but also provide strong technical support for the research and development design of new accelerometers, reducing the test cost and time cost in the research and development process.

[0019] 4. Provide effective guidance for the maintenance and calibration of the accelerometer. Based on this prediction model, the degradation situation of the magnetic property of the permanent magnet can be known in advance, so as to formulate a reasonable maintenance plan for the accelerometer. For example, when it is predicted that the magnetic property of the magnet is about to decline to the threshold value affecting the accuracy of the accelerometer, the accelerometer can be calibrated in time or the magnet component can be replaced to avoid equipment failures or performance degradation caused by magnetic property degradation, extend the service life of the accelerometer, reduce the overall maintenance cost of the equipment, and improve the operation efficiency and stability of the equipment.

[0020] Through the prediction model of the magnetic property degradation law of the permanent magnet in the accelerometer of the present invention, the problem that the magnetic property degradation law of the permanent magnet cannot be accurately predicted in the prior art can be effectively solved, the reliability of the accelerometer and the accuracy of stability evaluation can be improved, and strong support can be provided for the technological development in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A series of magnetization intensity-time change curves in the embodiment;

[0022] Figure 2 H in the embodiment E -S curve;

[0023] Figure 3 The magnetic viscosity curve of Hs and S in the embodiment;

[0024] Figure 4 The magnetic viscosity curves under an externally applied magnetic field of 1000 Oe at different temperatures in the embodiment;

[0025] Figure 5 The fitting curve between the magnetic viscosity coefficient and the temperature in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE INVENTION I: A method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to this embodiment includes the following steps:

[0027] Step 1: Perform magnetic viscosity performance tests on the permanent magnet using a vibrating sample magnetometer to obtain the magnetization intensity-time change curve, the magnetization intensity-time logarithm relationship curve, and the magnetic viscosity coefficient-externally applied magnetic field relationship curve;

[0028] Step 2: Analyze the influence of the demagnetizing field on the relationship between the total magnetic field and the externally applied magnetic field during the magnetic viscosity process, and obtain the relationship data between the total magnetic field and the externally applied magnetic field;

[0029] Step 3: Construct a prediction model for the magnetic property degradation amount, introduce temperature coefficient correction, and obtain the relationship between the magnetization intensity change amount, the storage time, the externally applied magnetic field, the demagnetization factor, and the initial magnetization intensity;

[0030] Step 4: Predict the magnetic property degradation law of the permanent magnet through the prediction model of the magnetic property degradation amount.

[0031] The magnetic property degradation of a permanent magnet is a process that evolves over time. The magnetization intensity vs. time curve intuitively shows the specific values of the magnetization intensity of the magnet at different times. From a microscopic perspective, the arrangement and orientation of magnetic domains inside the magnet change over time, and this change is reflected in the macroscopic magnetization intensity. By measuring this curve, the basic degradation trend of the magnetic properties of the magnet over time in its natural state can be understood, providing basic data in the time dimension for subsequent analysis. The magnetic viscosity phenomenon usually has a specific relationship with the logarithm of time. According to magnetic theory, the movement and rearrangement of magnetic domains inside the magnet follow a logarithmic law under certain conditions. By plotting the curve of magnetization intensity vs. the logarithm of time, the internal law of the magnetic viscosity phenomenon can be more clearly revealed, and the characteristics of the magnetic property change with the logarithm of time can be determined, which helps to accurately grasp the rate and trend of magnetic property degradation. An externally applied magnetic field is one of the important factors affecting the magnetic properties of a permanent magnet. Externally applied magnetic fields of different intensities have different effects on the magnetic domains inside the magnet, thus changing the magnetic viscosity coefficient. The magnetic viscosity coefficient reflects the ease of change of the magnetic properties of the magnet over time under the action of a magnetic field. Through this curve, the quantitative relationship between the externally applied magnetic field and the magnetic viscosity coefficient can be understood, providing a basis for subsequent consideration of the influence of the externally applied magnetic field on magnetic property degradation.

[0032] The shape of the magnet causes a demagnetizing field to be generated inside it. The demagnetizing field interacts with the externally applied magnetic field and jointly affects the magnetic properties of the magnet. Physically speaking, the surface magnetic poles of the magnet generate a demagnetizing field that is opposite in direction to the externally applied magnetic field, and its magnitude and distribution are closely related to the shape of the magnet. For example, the demagnetizing field distributions of slender magnets and block-shaped magnets are significantly different. By analyzing the influence of the demagnetizing field on the relationship between the total magnetic field and the externally applied magnetic field during the magnetic viscosity process, the demagnetizing field factor is incorporated into the overall consideration. The total magnetic field is the combined result of the externally applied magnetic field and the demagnetizing field, which more accurately reflects the actual magnetic field environment in which the magnet is located. Obtaining the relationship data between the total magnetic field and the externally applied magnetic field can more comprehensively describe the magnetic field state of the magnet in practical applications, providing more accurate magnetic field information for constructing an accurate prediction model.

[0033] Based on the data obtained in Step 1 and Step 2, a prediction model for the magnetic property degradation amount is constructed using mathematical methods. This model organically combines factors such as the change in magnetization intensity, storage time, applied magnetic field, demagnetization factor, and initial magnetization intensity. Physically, these factors are interrelated and interact with each other, jointly determining the degree of magnetic property degradation of the permanent magnet steel. For example, the initial magnetization intensity is the starting state of the magnetic properties of the permanent magnet steel. The applied magnetic field and the demagnetization factor jointly affect the movement of magnetic domains inside the magnet, and the storage time is the factor of time accumulation for magnetic property degradation. By establishing the mathematical relationship between them, the degradation law of magnetic properties can be quantitatively described. Temperature has a significant impact on the magnetic properties of permanent magnet steel. As the temperature increases, the thermal motion of atoms inside the magnet intensifies, leading to a decrease in the stability of magnetic domains, thereby causing magnetic property degradation. At different temperatures, parameters such as the magnetic viscosity coefficient and saturation magnetization intensity of the magnet will change. By measuring the variation relationship of magnetic properties with temperature and introducing a temperature coefficient for correction, the prediction model can more accurately reflect the magnetic property degradation of the permanent magnet steel in different temperature environments, further improving the accuracy and applicability of the model.

[0034] By using the prediction model for the magnetic property degradation amount constructed in Step 3 and combining actual parameters such as storage time, applied magnetic field, demagnetization factor, initial magnetization intensity, and temperature, the degradation law of the magnetic properties of permanent magnet steel can be predicted. In practical applications, the model can be verified and optimized through experimental data, continuously improving the accuracy and reliability of the model. For example, by comparing the model prediction results with the actual measured magnetic property data and adjusting the model parameters according to the error situation, the model can better adapt to different permanent magnet steels and actual application scenarios.

[0035] In this embodiment, by constructing a new prediction model for the magnetic property degradation law of the accelerometer permanent magnet steel, various key influencing factors such as the applied magnetic field, magnet shape, and temperature change can be effectively integrated, and the long-term degradation law of the magnetic properties of the permanent magnet steel can be predicted comprehensively, systematically, and accurately. The emergence of this innovative model will completely change the situation in the prior art where the degradation law of the magnetic properties of the magnet steel cannot be accurately predicted, and greatly improve the accuracy of the reliability and stability assessment of the accelerometer. This model will play an important role in all aspects of the design, production, use, and maintenance of quartz accelerometers, providing strong support for the technological development in related fields and promoting key fields such as aerospace, military defense, industrial automation control, and inertial navigation to a higher development stage.

[0036] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the magnetic viscosity performance test of the permanent magnet steel based on the vibrating sample magnetometer in Step 1 is specifically carried out according to the following steps: ① Draw a hysteresis loop through VSM testing, and obtain the remanent magnetization M and coercive force H of the magnet through the hysteresis loop c ;

[0037] ②Apply the magnetic field again through the VSM to saturate the magnetization of the magnet, reverse the magnetic field direction, and set a series of constant reverse magnetic fields with different intensities, that is, the applied magnetic field H E , the applied magnetic field H E Take 8 to 12 values within the range of 0 Oe to 2H c ; for each selected applied magnetic field H E , use the VSM to measure the change curve of the magnetization intensity of the magnet with time, and obtain a series of magnetization intensity-time change curves; according to the measured magnetization intensity-time change curve, obtain the magnetic viscosity coefficient S corresponding to the applied magnetic field H E , with the applied magnetic field H E as the abscissa and S as the ordinate, plot the H E -S curve. Other steps and parameters are the same as those in the first specific implementation manner.

[0038] Specific implementation manner three: The difference between this implementation manner and the second specific implementation manner is that the specific method for obtaining the relationship data between the total magnetic field and the applied magnetic field in step two is: calculate the sum of the demagnetizing field H d and the applied magnetic field H E as the total magnetic field H s , and correlate the calculated H s with the corresponding S value in the H E -S curve to obtain the magnetic viscosity curve of Hs and S. Other steps and parameters are the same as those in the second specific implementation manner.

[0039] Specific implementation manner four: The difference between this implementation manner and the third specific implementation manner is that H d =-N·M; N is the demagnetization factor, which is determined by the shape of the magnet, and M is the remanent magnetization. Other steps and parameters are the same as those in the third specific implementation manner.

[0040] Specific implementation manner five: The difference between this implementation manner and the third specific implementation manner is that the specific steps for constructing the magnetic property degradation prediction model in step three are as follows:

[0041] ①Perform Gaussian distribution fitting on the magnetic viscosity curve of Hs and S to obtain formula (1);

[0042]

[0043] where a1, a2, a3, and a4 are fitting parameters;

[0044] ②According to the logarithmic relationship formula between the magnetization intensity and the magnetic viscosity coefficient and the magnetization intensity attenuation amount calculation formula, obtain the change relationship between the magnetization intensity attenuation amount △M(y) and the storage life y (unit: year) to obtain formula (2);

[0045] ΔM(y) = S(H S )(ln(y) + 11.37) (2);

[0046] ③ Integrate formula (1) and formula (2) to obtain the relationship between the magnetization intensity attenuation, the residual magnetization intensity, and the storage life, and get formula (3);

[0047]

[0048] ④ From formula (3) and the attenuation formula of the magnetization intensity based on the logarithmic change model, obtain the calculation formula of the magnetization intensity of the magnet in the y-th year (4);

[0049]

[0050] ⑤ Simplify formula (4) to get formula (5);

[0051] Other steps and parameters are the same as those in the third specific implementation manner.

[0052] Specific implementation manner six: The difference between this implementation manner and the fifth specific implementation manner is that in step ②, the calculation formula for the magnetization intensity attenuation: △M(y) = M0 - M(y); the logarithmic relationship formula between the magnetization intensity and the magnetic viscosity coefficient: M(y) = M0 - S·lnt; where M(y) is the magnetization intensity at time y, M0 is the initial magnetization intensity, and S is the magnetic viscosity coefficient. Other steps and parameters are the same as those in the fifth specific implementation manner.

[0053] Specific implementation manner seven: The difference between this implementation manner and the sixth specific implementation manner is that the time unit obtained from the magnetic viscosity curve test is seconds, and the relationship between △M(y) and the storage time t (unit: seconds) conforms to:

[0054] ΔM(y) = S(H S )lnt

[0055] Calculated by 365 days in a year, then one year is 3.1536×10^7 s, so t = 3.1536×10 7 ^y, substituting into the above formula gives

[0056] ΔM(y) = S(H S )(ln(y) + 11.37). Other steps and parameters are the same as those in the sixth specific implementation manner.

[0057] Specific implementation manner eight: The difference between this implementation manner and the fifth specific implementation manner is that the simplification in step ⑤ is to consider that under a closed magnetic circuit, the demagnetizing field of the magnet can be ignored. Other steps and parameters are the same as those in the fifth specific implementation manner.

[0058] Embodiment 9: The difference between this embodiment and Embodiment 3 is that in Step 3, the introduction of temperature coefficient correction takes into account the attenuation of magnetic properties at different temperatures. The magnetic viscosity curve is measured at 20 to 100 degrees, the relationship between the magnetic viscosity coefficient S and the temperature T is obtained, and linear fitting is performed to obtain (6);

[0059] S(T) = S T0 + b·T (6);

[0060] where S T0 is the magnetic viscosity coefficient at room temperature, and b is the fitting parameter. Other steps and parameters are the same as those in Embodiment 3.

[0061] Embodiment 10: The difference between this embodiment and Embodiments 5 and 9 is that a prediction model for the magnetic property degradation law of permanent magnet steels based on magnetic viscosity is constructed from formula (5) and formula (6), and the magnetization intensity of the storage life y at temperature T is obtained as formula (7) or (8);

[0062] When it is an open-circuit environment, the formula is:

[0063]

[0064] When it is a closed-circuit environment, the formula is:

[0065] Other steps and parameters are the same as those in Embodiments 5 and 9.

[0066] The beneficial effects of the present invention are verified through the following examples:

[0067] Example: The prediction method for the magnetic property degradation law of permanent magnet steels based on magnetic viscosity includes the following steps:

[0068] The hysteresis loop is plotted through VSM testing, and the remanent magnetization M and coercive force H of the alnico8 magnet are obtained from the hysteresis loop c ; The remanent magnetization is 9.6 kGs, and the test magnet size is 1*1*3 mm; H c is 1500 Oe;

[0069] Again, a magnetic field is applied through VSM to saturate the magnet, the magnetic field direction is reversed, and a series of different intensities of constant reverse magnetic fields, that is, the applied magnetic field H E , the applied magnetic field H E takes 10 values in the range of 300 Oe to 3000 Oe, with each value spaced 300 Oe apart; for each selected applied magnetic field H E , the VSM is used to measure the magnetization intensity change curve of the magnet over time, and a series of magnetization intensity - time change curves are obtained; according to the measured magnetization intensity - time change curves, the corresponding applied magnetic field HE The magnetic viscosity coefficient S, with the externally applied magnetic field H E as the abscissa and S as the ordinate, plot the H E -S curve;

[0070] Obtaining the relationship data between the total magnetic field and the externally applied magnetic field is specifically: calculating the demagnetizing field H d and the externally applied magnetic field H E whose sum is the total magnetic field H s , and correlating the calculated H s with the corresponding S value in the H E -S curve to obtain the magnetic viscosity curve of Hs and S; H d = -N·M; N is the demagnetization factor taken as 0.12, determined by the shape of the magnet, and M is the remanent magnetization taken as 9.6 kGs;

[0071] Perform Gaussian fitting on the Hs-S curve to obtain

[0072]

[0073] The calculated magnetization intensity of the magnet in the y-th year is:

[0074]

[0075] In a closed-circuit environment, the magnetization intensity of the magnet satisfies:

[0076]

[0077] Test the magnetic viscosity curves at temperature environments of 40°C, 60°C, 80°C, and 100°C. As Figure 4 shown, linearly fit the relationship between the magnetic viscosity coefficient and temperature. As Figure 5 shown, obtain b = 0.00772 Gs / °C. Therefore, obtain:

[0078]

[0079] Based on the above formula, according to the ambient temperature T of the permanent magnet and the external magnetic field strength H E , the magnetization intensity of the permanent magnet stored for different years can be predicted. In precision instruments such as accelerometers, there is a corresponding relationship between the magnetization intensity of the permanent magnet and the instrument parameters. Therefore, the long-term change law of the instrument can be predicted, and the service life of the instrument can be extended through means such as circuit correction and temperature compensation. The prediction law obtained by this method has wide applicability, is simple and easy to operate, and the prediction results are reliable, providing a reference value for the service life of permanent magnets in various environments.

Claims

1. A method for predicting the degradation law of the magnetic properties of a permanent magnet based on magnetic viscosity, characterized in that The method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity includes the following steps: Step 1: Conduct magnetic viscosity performance tests on the permanent magnet using a vibrating sample magnetometer to obtain the magnetization intensity vs. time curve, the magnetization intensity vs. logarithm of time curve, and the magnetic viscosity coefficient vs. applied magnetic field curve; Step 2: Analyze the influence of the demagnetizing field on the relationship between the total magnetic field and the applied magnetic field during the magnetic viscosity process, and obtain the relationship data between the total magnetic field and the applied magnetic field; Step 3: Construct a prediction model for the magnetic property degradation amount, introduce temperature coefficient correction, and obtain the relationship between the change in magnetization intensity, storage time, applied magnetic field, demagnetization factor, and initial magnetization intensity; Step 4: Predict the magnetic property degradation law of the permanent magnet through the prediction model for the magnetic property degradation amount.

2. The method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claim 1, wherein The specific steps for conducting magnetic viscosity performance tests on the permanent magnet using a vibrating sample magnetometer in Step 1 are as follows: ①Draw the hysteresis loop through VSM testing and obtain the remanent magnetization M and coercivity H of the magnet from the hysteresis loop c ; ②Apply a magnetic field again through VSM to saturate the magnetization of the magnet, reverse the magnetic field direction, and set a series of constant reverse magnetic fields with different intensities, namely the applied magnetic field H E , the applied magnetic field H E takes 8 - 12 values within the range of 0 Oe to 2H c ; for each selected applied magnetic field H E , use VSM to measure the magnetization intensity change curve of the magnet over time to obtain a series of magnetization intensity - time change curves; according to the measured magnetization intensity - time change curves, obtain the magnetic viscosity coefficient S corresponding to the applied magnetic field H E , with the applied magnetic field H E as the abscissa and S as the ordinate, plot the H E -S curve.

3. The method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claim 2, wherein The specific data acquisition of the relationship between the total magnetic field and the applied magnetic field in Step 2 is as follows: Calculate the demagnetizing field H d and the applied magnetic field H E , and their sum is the total magnetic field H s . Correlate the calculated H s with the corresponding S value in the H E -S curve to obtain the magnetic viscosity curve of Hs and S.

4. The prediction method for the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claim 3, characterized in that H d = -N·M; where N is the demagnetization factor, determined by the shape of the magnet, and M is the remanent magnetization.

5. A method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claim 3, characterized in that The specific steps for constructing the prediction model for the magnetic property degradation amount in Step 3 are as follows: ① Fit the magnetic viscosity curve of Hs and S with a Gaussian distribution to obtain Equation (1); where a1, a2, a3, and a4 are fitting parameters; ② According to the logarithmic relationship formula between magnetization intensity and magnetic viscosity coefficient and the magnetization intensity attenuation amount calculation formula, obtain the variation relationship between the magnetization intensity attenuation amount △M(y) and the storage years y (unit: year) to obtain Equation (2); ΔM(y) = S(H S )(ln(y) + 11.37) (2); ③ Integrate Equation (1) and Equation (2) to obtain the relationship between the magnetization intensity attenuation amount, the residual magnetization intensity, and the storage years to obtain Equation (3); ④ From Equation (3) and the attenuation amount formula of the magnetization intensity based on the logarithmic change model, obtain the magnetization intensity calculation formula of the magnet in the y-th year Equation (4); ⑤ Simplify Equation (4) to obtain Equation (5); 6. The method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claim 5, wherein In Step ②, the magnetization intensity attenuation amount calculation formula: △M(y) = M0 - M(y); the logarithmic relationship formula between magnetization intensity and magnetic viscosity coefficient: M(y) = M0 - S·lnt; where M(y) is the magnetization intensity at time y, M0 is the initial magnetization intensity, and S is the magnetic viscosity coefficient.

7. A method for predicting the degradation law of the magnetic properties of a permanent magnet based on magnetic viscosity, as described in claim 6, wherein The time unit obtained from the magnetic viscosity curve test is seconds, and the relationship between △M(y) and the storage time t (unit: second) conforms to: ΔM(y) = S(H S ) lnt Calculated based on 365 days in a year, one year is 3.1536×10^7 s, so t = 3.1536×10 7 y, substituting into the above formula gives ΔM(y) = S(H S )(ln(y) + 11.37).

8. A method for predicting the degradation law of the magnetic properties of a permanent magnet based on magnetic viscosity according to claim 5, characterized in that The simplification in Step ⑤ is considering that in a closed magnetic circuit, the demagnetizing field of the magnet can be ignored.

9. The prediction method for the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claim 3, wherein The introduction of temperature coefficient correction in Step 3 is considering the attenuation of magnetic properties at different temperatures. Test the magnetic viscosity curve at 20 - 100 degrees to obtain the relationship between the magnetic viscosity coefficient S and the temperature T, and perform linear fitting to obtain (6); S(T) = S T0 + b·T (6); Where S T0 is the magnetic viscosity coefficient at room temperature, and b is the fitting parameter.

10. A method for predicting the magnetic property degradation law of a permanent magnet based on magnetic viscosity according to claims 5 and 9, characterized in that Construct a prediction model for the magnetic property degradation law of a permanent magnet based on magnetic viscosity from Equation (5) and Equation (6), and obtain the magnetization intensity of the storage years y at temperature T as Equation (7) or (8); When it is an open-circuit environment, the formula is: When it is a closed-circuit environment, the formula is:

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