Marine ceramic capacitive pressure sensor structure integrity state estimation method

Abstract

The invention provides a method for estimating the structural integrity state of a marine ceramic capacitive pressure sensor, and the method comprises the steps: building a mathematical model of a ceramic capacitor diaphragm, and enabling the mathematical model to be used for describing the deformation behavior of the diaphragm and the relation between the deformation behavior and the capacitance change under the action of external pressure; carrying out basic hypothesis analysis on the diaphragm; respectively calculating the deflection of the diaphragm in small deflection deformation and large deflection deformation, and calculating the maximum allowable strain of the diaphragm; the capacitance and capacitance sensitivity of the pressure sensor are calculated, and the relation between the capacitance variation and the pressure is obtained; and comprehensively evaluating the structural integrity of the pressure sensor by combining the deformation behavior of the diaphragm, the maximum allowable strain and the relationship between the capacitance and the pressure. According to the method, the ceramic capacitor technology is combined, numerical simulation and experimental verification are carried out by establishing a mathematical model based on finite element analysis software and a deflection deformation theory, and thus the reliability and accuracy of the sensor in practical application are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic capacitor pressure sensors, and in particular to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor. Background Art

[0002] The pressure sensor is mainly responsible for measuring the pressure of the gas or liquid in its environment and feeding this data back to the main control unit of the system to ensure accurate control of the system. Whether in automobiles, industrial automation, home appliances or consumer electronics, pressure sensors play a key role. According to their working principles, pressure sensors are mainly divided into: silicon piezoresistive technology, ceramic resistor technology, glass micro-melting technology and ceramic capacitor technology. Among them, silicon piezoresistive technology uses the piezoresistive properties of semiconductors to work. Although this technology has significant advantages in size, cost and sensitivity, its low tolerance to media, poor temperature characteristics and poor long-term stability are still major disadvantages. Although the industry has adopted some special packaging technologies such as oil filling and back pressure to make up for these shortcomings, this has also led to increased costs.

[0003] Ceramic resistor technology converts pressure signals into voltage signals by printing a Wheatstone bridge on the surface of ceramics and utilizing its piezoresistive effect. This technology has advantages in cost and manufacturing process, but the signal output sensitivity is low, and its overload resistance is also a problem for large pressure changes. Glass micro-melting technology is a method that combines silicon strain gauges with stainless steel structures through high-temperature sintering. Although this technology has obvious advantages in medium tolerance and overload resistance, its high cost and manufacturing difficulty limit its wide application. Ceramic capacitor technology uses a fixed ceramic base and a movable ceramic diaphragm structure. When the pressure on the diaphragm changes, the capacitance value between the two will also change. This technology is not only moderately expensive, but also performs well in range, temperature characteristics and long-term stability. In general, ceramic capacitive pressure sensors have been widely used in various fields due to their many advantages, such as corrosion resistance, impact resistance, overload resistance and stable output. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor. The method combines ceramic capacitor technology, is based on finite element analysis software and deflection deformation theory, and ensures the reliability and accuracy of the sensor in practical applications by establishing a mathematical model, performing numerical simulation and experimental verification.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor, the method comprising the following steps:

[0007] A mathematical model of ceramic capacitor diaphragm is established to describe the deformation behavior of the diaphragm under external pressure and its relationship with the change of capacitance.

[0008] Conduct basic hypothesis analysis of the diaphragm;

[0009] Calculate the deflection of the diaphragm in small deflection deformation and large deflection deformation respectively, and calculate the maximum allowable strain of the diaphragm;

[0010] Calculate the capacitance and capacitance sensitivity of the pressure sensor, and derive the relationship between the capacitance change and pressure;

[0011] The structural integrity of the pressure sensor is comprehensively evaluated by combining the deformation behavior of the diaphragm, the maximum allowable strain, and the relationship between capacitance and pressure.

[0012] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the basic assumption analysis of the diaphragm includes:

[0013] The line segments perpendicular to the mid-surface remain straight lines and are still perpendicular to the deformed mid-surface;

[0014] The normal stress perpendicular to the mid-plane is relatively small and can be ignored, so only the in-plane stress and deformation need to be considered;

[0015] Only the deformation of the diaphragm caused by pressure is considered.

[0016] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the deflection calculation of the diaphragm under small deflection deformation is expressed as the following deflection formula:

[0017]

[0018] Where d0 is the deflection of the center point of the diaphragm, R is the radius of the diaphragm, and r is the distance from a point on the movable electrode of the diaphragm to the center of the diaphragm.

[0019] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the deflection calculation of the diaphragm under large deflection deformation is expressed as the following deflection formula:

[0020]

[0021] Among them, μ is Poisson's ratio, E is Young's elastic modulus, and h is the thickness of the diaphragm.

[0022] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the calculation of the maximum allowable strain of the diaphragm includes:

[0023] The maximum allowable strain of the elastic diaphragm in the event of plastic deformation or cracking is calculated as follows:

[0024]

[0025] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the method for calculating the capacitance and capacitance sensitivity of the pressure sensor comprises:

[0026] In the case of diaphragm deformation, the capacitance calculation of the pressure sensor is expressed as follows:

[0027]

[0028] Where C0 is the capacitance value when the pressure is 0, ε0 is the dielectric constant of vacuum, ε a is the relative dielectric constant of air.

[0029] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the method for calculating the capacitance and capacitance sensitivity of the pressure sensor comprises:

[0030] Calculate the sensitivity of the capacitor, expressed as the following formula:

[0031]

[0032] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, when establishing a mathematical model, the Timoshenko plate and shell theory is used to analyze the deformation of the diaphragm.

[0033] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the following steps are further performed:

[0034] Use ANSYS software to perform numerical simulation, set the properties of ceramic materials, and simulate the deformation of the diaphragm under different pressure differences;

[0035] Divide the diaphragm grid to ensure simulation accuracy and analyze the stress and deflection distribution of the diaphragm under different pressures;

[0036] Adjust simulation parameters and perform multiple simulations to ensure the stability and repeatability of simulation results.

[0037] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the following steps are further performed:

[0038] Introduce temperature, humidity or other multi-physics factors to analyze their impact on the deformation behavior and capacitance characteristics of ceramic capacitor diaphragms.

[0039] According to a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor provided by the present invention, the following steps are further performed:

[0040] Using big data and machine learning technology, we collect and analyze the performance data of pressure sensors in actual applications and establish a data-driven evaluation model.

[0041] It can be seen that compared with the prior art, the method provided by the present invention has the following beneficial effects:

[0042] 1. The present invention can accurately calculate the deformation and stress distribution of the diaphragm under different pressure conditions by establishing a mathematical model of the ceramic capacitor diaphragm, combining finite element analysis and experimental verification. Ceramic capacitor technology itself has corrosion resistance, impact resistance and overload resistance. On this basis, the evaluation method of the present invention can ensure the rationality and accuracy of the sensor design and significantly improve the reliability of the sensor in practical applications.

[0043] 2. The present invention uses ANSYS software to perform numerical simulation and optimize design parameters. By reducing the number of repeated tests, the R&D cost is reduced. Compared with other technologies, ceramic capacitor technology has moderate cost and relatively simple manufacturing process. The present invention can greatly reduce the uncertainty in design and production by comparing and analyzing the mathematical model of the ceramic capacitor core with the results of finite element analysis. In addition, the optimized design parameters can not only improve the performance of the sensor, but also reduce the production and maintenance costs.

[0044] 3. The present invention ensures the reliability of the sensor under high pressure and overload conditions through a comprehensive structural integrity assessment. The outstanding performance of ceramic capacitor technology in range, temperature characteristics and long-term stability ensures its long-term stable operation in harsh environments. It can improve the service life and reliability of the sensor, reduce maintenance and replacement costs, and ensure its stability during long-term operation.

[0045] 4. The present invention considers the deflection calculation of the diaphragm under small deflection deformation and large deflection deformation respectively, which is helpful to more comprehensively evaluate the deformation of the diaphragm under different pressure conditions. Among them, the small deflection deformation theory is applicable to the case of lower pressure, while the large deflection deformation theory is applicable to the case of higher pressure.

[0046] 5. The present invention can ensure that the diaphragm will not be damaged due to excessive deformation when subjected to pressure by calculating the maximum allowable strain of the diaphragm, thereby ensuring the long-term stability and reliability of the sensor.

[0047] 6. The results of the present invention are intuitive, and the results such as the relationship between the capacitance change and the pressure obtained by calculation are intuitive and easy to understand, and can be conveniently used for performance evaluation and fault diagnosis of the sensor.

[0048] In summary, the present invention provides a method for evaluating the structural integrity of a marine ceramic capacitor pressure sensor, which aims to systematically analyze and evaluate the structural integrity of the ceramic capacitor pressure sensor under different pressure conditions through mathematical modeling, numerical simulation and experimental verification. The method mainly includes establishing a mathematical model of the diaphragm, performing numerical simulation, building an experimental platform for verification, and finally evaluating the reliability and accuracy of the sensor through experimental data analysis and parameter optimization.

[0049] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a schematic flow chart of an embodiment of a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor.

[0051] Figure 2 It is a schematic diagram of the internal structure of the core of a capacitive pressure sensor in an embodiment of a method for estimating the structural integrity state of a marine ceramic capacitive pressure sensor of the present invention.

[0052] Figure 3 It is a schematic cross-sectional diagram of ANSYS mesh division and stress distribution of a capacitive pressure sensor core in an embodiment of a method for estimating the structural integrity state of a marine ceramic capacitive pressure sensor of the present invention.

[0053] Figure 4 It is a structural schematic diagram of a diaphragm displacement of 9.2 μm under a pressure of 1.2 MPa in an embodiment of a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor of the present invention.

[0054] Figure 5 About Figure 4 sectional view of .

[0055] Figure 6 It is a schematic diagram of the relationship between pressure and diaphragm displacement in an embodiment of a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0058] See also Figures 1 to 6 This embodiment provides a method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor, the method comprising the following steps:

[0059] Step S1, establishing a mathematical model of a ceramic capacitor diaphragm, used to describe the deformation behavior of the diaphragm under external pressure and its relationship with capacitance change;

[0060] Step S2, performing basic assumption analysis of the diaphragm;

[0061] Step S3, respectively calculating the deflection of the diaphragm in small deflection deformation and large deflection deformation, and calculating the maximum allowable strain of the diaphragm;

[0062] Step S4, calculating the capacitance and capacitance sensitivity of the pressure sensor, and obtaining the relationship between the capacitance change and the pressure;

[0063] Step S5, comprehensively evaluating the structural integrity of the pressure sensor based on the deformation behavior of the diaphragm, the maximum allowable strain, and the relationship between capacitance and pressure.

[0064] In the above step S2, the basic assumption analysis of the diaphragm includes:

[0065] The line segments perpendicular to the mid-surface remain straight lines and perpendicular to the deformed mid-surface. This is part of the small deformation assumption and is applicable when the deformation of the diaphragm is not large.

[0066] The normal stress perpendicular to the mid-plane is relatively small and can be ignored. Only the in-plane stress and deformation need to be considered. This is applicable to thin plate structures where bending stress dominates.

[0067] Only the diaphragm deformation caused by pressure is considered, and other possible deformation sources such as temperature, vibration, etc. are ignored.

[0068] Specifically, the line segments perpendicular to the mid-surface remain straight lines and are still perpendicular to the deformed mid-surface: This means that when the diaphragm is deformed, although the mid-surface (i.e., the original plane of the diaphragm) will change, any line segments perpendicular to the mid-surface (i.e., normal lines) remain straight lines after deformation and are still perpendicular to the deformed mid-surface. This assumption ignores the shear deformation of the diaphragm in the thickness direction, that is, it is assumed that the deformation of the diaphragm in the thickness direction is uniform, without distortion or shearing. The rationality lies in that for thin film structures (such as plastic films, rubber films, etc.), their thickness is much smaller than the dimensions in the other two directions, so the shear deformation in the thickness direction can be ignored relative to the deformation of the mid-surface.

[0069] The normal stress perpendicular to the mid-plane is relatively small and can be ignored: During the deformation of the diaphragm, the normal stress perpendicular to the mid-plane (i.e., the normal stress in the thickness direction) is very small and can be ignored. This is because the diaphragm is mainly subjected to in-plane stress (i.e., stress parallel to the mid-plane), while the stress in the thickness direction is difficult to produce significant normal stress due to the small thickness of the diaphragm and the weak constraint of the material in the thickness direction. After ignoring the normal stress perpendicular to the mid-plane, the mechanical analysis of the diaphragm can be further simplified, and only the in-plane stress and deformation need to be considered.

[0070] Consider only the deformation of the diaphragm caused by pressure: This assumption limits the source of the diaphragm deformation, that is, it is assumed that the deformation of the diaphragm is mainly caused by external pressure (or internal pressure, depending on the specific situation). In actual applications, the diaphragm may be subjected to various forces, such as temperature stress, gravity, etc. But under this assumption, these secondary factors are ignored and only the deformation caused by pressure is considered. The rationale is that for many diaphragm structures, pressure is the main factor causing deformation. Especially in applications such as pressure sensors and diaphragm pumps, the deformation of the diaphragm directly determines the performance parameters of the equipment. Therefore, in these cases, it is reasonable to only consider the deformation caused by pressure.

[0071] In the above step S3, for the case of small deflection deformation: when the pressure difference between the two sides is P, the deflection d of the point at a distance r from the center of the diaphragm is r for:

[0072]

[0073] Where d0 is the deflection of the center point of the diaphragm, R is the radius of the diaphragm, and r is the distance from a point on the movable electrode of the diaphragm to the center of the diaphragm.

[0074] In the above step S3, for the case where the two plates are not in contact with each other due to large deflection, the deflection formula of the point at a distance r from the center of the diaphragm is the same as the above formula, but d0 is determined by the following formula:

[0075]

[0076] Among them, μ is Poisson's ratio, E is Young's elastic modulus, and h is the thickness of the diaphragm.

[0077] In the above step S3, the calculation of the maximum allowable strain of the diaphragm includes:

[0078] The maximum allowable strain of the elastic diaphragm in the event of plastic deformation or cracking is calculated as follows:

[0079]

[0080] In the above step S4, when the diaphragm is deformed, the capacitance of the sensor can be calculated by the following formula:

[0081] In the case of diaphragm deformation, the capacitance calculation of the pressure sensor is expressed as follows:

[0082]

[0083] Where C0 is the capacitance value when the pressure is 0, ε0 is the dielectric constant of vacuum, ε a is the relative dielectric constant of air.

[0084] In the above step S4, the sensitivity of the capacitor is calculated and expressed as the following formula:

[0085]

[0086] In this embodiment, a mathematical model of a ceramic capacitor diaphragm is established by using the basic assumptions and deformation analysis of the diaphragm. The model includes two cases of small deflection deformation and large deflection deformation, and the deflection of the diaphragm under different pressure differences is calculated respectively.

[0087] In this embodiment, when establishing the mathematical model, the Timoshenko plate and shell theory is used to analyze the deformation of the diaphragm to ensure the rationality and accuracy of the mathematical model.

[0088] Specifically, two points are added to the model, a path along the radial direction is set, the deflection of each point from the center along the radial direction to the edge is calculated, and it is determined that the shape of the deflection curve of each point on the diaphragm from the center along the radial direction is basically consistent with the model.

[0089] In the above step S5, a comprehensive evaluation is conducted on the structural integrity of the marine ceramic capacitor pressure sensor. The evaluation results include the stability, reliability, sensitivity and durability of the sensor under different pressure conditions. This evaluation result is of great significance for ensuring the safe and reliable operation of the sensor in the marine environment.

[0090] Therefore, the structural integrity state estimation method of the marine ceramic capacitor pressure sensor is a comprehensive, systematic and quantitative evaluation report, which not only reveals the deformation behavior and capacitance change law of the sensor when subjected to pressure, but also provides a strong guarantee for its safe and reliable operation in the marine environment.

[0091] In this embodiment, the following is also performed:

[0092] Use ANSYS software to set the ceramic material properties (such as Young's modulus, Poisson's ratio, etc.) and set different pressures for the diaphragm.

[0093] The diaphragm is meshed, with 0.2mm mesh for the diaphragm and 0.5mm mesh for the body. Because the diaphragm and body have relatively regular structures, they are meshed with hexahedrons to improve calculation accuracy and speed. Run the solver.

[0094] Adjust simulation parameters, including load size and material properties. Perform multiple simulations to ensure the stability and repeatability of the simulation results. Calculate the stress and deflection distribution of the diaphragm under different pressures to verify the accuracy of the mathematical model.

[0095] Furthermore, load size: according to different working conditions, the applied pressure difference is adjusted to simulate the deformation behavior of the diaphragm under various pressure conditions. Material properties: according to different ceramic materials, material property parameters such as Young's modulus, Poisson's ratio and density are adjusted.

[0096] In this embodiment, the evaluation method is experimentally verified, including:

[0097] (1) Build an experimental platform, including a pressure loading system, a sensor fixture, a capacitance measurement system, etc.

[0098] (2) Prepare ceramic capacitor pressure sensor samples and perform preliminary calibration to ensure that the initial capacitance value of the sensor at zero pressure is accurate.

[0099] (3) On the experimental platform, the ceramic capacitor pressure sensor is tested under different pressures and the changes in capacitance values ​​are recorded.

[0100] (4) Analyze the experimental results and verify the accuracy of the mathematical model and numerical simulation.

[0101] In this embodiment, the experimental results are analyzed and parameters are optimized, including:

[0102] (1) Based on the experimental data, analyze the response curve of the sensor under different pressures and determine the linearity, sensitivity and repeatability of the sensor.

[0103] (2) Compare experimental data and numerical simulation results, determine the error range, optimize model parameters, reduce errors, and improve model accuracy.

[0104] (3) Conduct multiple experiments to ensure the stability and repeatability of the experimental results and further verify the reliability of the sensor.

[0105] Through models and experimental results, the structural integrity of ceramic capacitor pressure sensors under different pressures is evaluated to ensure their reliability under high pressure and overload conditions.

[0106] In this embodiment, the following is further performed: introducing temperature, humidity or other multi-physical field factors to analyze the influence on the deformation behavior and capacitance characteristics of the ceramic capacitor diaphragm.

[0107] Furthermore, in addition to temperature and humidity, other multi-physics factors such as vibration and electromagnetic fields may also affect the deformation behavior and capacitance characteristics of ceramic capacitor diaphragms. For example, long-term vibration may cause the connection between the ceramic diaphragm and the electrode to loosen or break, thereby affecting the performance of the capacitor; in a strong electromagnetic field environment, ceramic capacitors may be affected by electromagnetic interference, resulting in capacitance fluctuations or unstable performance.

[0108] In this embodiment, the following is also performed: using big data and machine learning technology to collect and analyze performance data of pressure sensors in actual applications and establish a data-driven evaluation model.

[0109] Specifically, pressure sensors are deployed in the environment that needs to be monitored to ensure that the sensors can accurately capture the required data; a data acquisition system is established to collect data from sensors in real time or periodically; data from different sensors and systems are integrated to form a unified data set; the collected raw data is cleaned to remove noise, missing values, and outliers. Noise can be removed by filtering algorithms (such as mean filtering, median filtering, and Gaussian filtering), missing values ​​can be processed using interpolation, forward filling, backward filling, and other methods, and outliers can be detected and processed using methods such as Z-score, IQR, and Isolation Forest.

[0110] Then, the cleaned data is converted into a format that the machine learning model can understand, including data normalization and standardization to ensure the stability and accuracy of model training. For example, methods such as minimum-maximum normalization or Z-score normalization can be used to scale the data to a suitable range.

[0111] Select the appropriate machine learning algorithm: According to the characteristics of the data and application requirements, select the appropriate machine learning algorithm to build the evaluation model, including linear regression, decision tree, random forest, neural network, etc.; use the preprocessed data and extracted features to train the machine learning model. During the training process, it is necessary to continuously optimize the parameters and structure of the model to improve the prediction accuracy and generalization ability of the model.

[0112] Use the test data set to evaluate the performance of the model, including accuracy, recall, F1 score and other indicators, and optimize the model based on the evaluation results, including adjusting the model parameters, selecting a more appropriate algorithm or performing feature selection, etc. Display the evaluation results of the model in the form of charts, reports, etc., so that users can intuitively understand the performance of the pressure sensor.

[0113] Deploy the trained model to actual application scenarios to achieve real-time monitoring and evaluation of pressure sensor performance; use the model to monitor sensor data in real time to promptly identify and resolve potential problems and hidden dangers; and continuously optimize the model's structure and parameters based on feedback and data changes in actual applications to improve the model's adaptability and accuracy.

[0114] In summary, this embodiment provides a method for evaluating the structural integrity of a marine ceramic capacitor pressure sensor, which aims to systematically analyze and evaluate the structural integrity of the ceramic capacitor pressure sensor under different pressure conditions through mathematical modeling, numerical simulation and experimental verification. The method mainly includes establishing a mathematical model of the diaphragm, performing numerical simulation, building an experimental platform for verification, and finally evaluating the reliability and accuracy of the sensor through experimental data analysis and parameter optimization.

[0115] Furthermore, this embodiment can accurately calculate the deformation and stress distribution of the diaphragm under different pressure conditions by establishing a mathematical model of the ceramic capacitor diaphragm, combining finite element analysis and experimental verification. Ceramic capacitor technology itself has corrosion resistance, impact resistance and overload resistance. On this basis, the evaluation method of the present invention can ensure the rationality and accuracy of the sensor design and significantly improve the reliability of the sensor in practical applications.

[0116] Furthermore, this embodiment uses ANSYS software to perform numerical simulation and optimize design parameters. By reducing the number of repeated tests and reducing R&D costs, ceramic capacitor technology has moderate cost and relatively simple manufacturing process compared to other technologies. The present invention can greatly reduce the uncertainty in design and production by comparing and analyzing the results of the ceramic capacitor core mathematical model and finite element analysis. In addition, the optimized design parameters can not only improve the performance of the sensor, but also reduce production and maintenance costs.

[0117] Furthermore, this embodiment ensures the reliability of the sensor under high pressure and overload conditions through a comprehensive structural integrity assessment. The outstanding performance of ceramic capacitor technology in range, temperature characteristics and long-term stability ensures its long-term stable operation in harsh environments. The service life and reliability of the sensor can be improved, maintenance and replacement costs can be reduced, and its stability can be ensured during long-term operation.

[0118] Furthermore, this embodiment considers the calculation of the deflection of the diaphragm under small deflection deformation and large deflection deformation respectively, which is helpful to more comprehensively evaluate the deformation of the diaphragm under different pressure conditions. Among them, the small deflection deformation theory is applicable to the case of lower pressure, while the large deflection deformation theory is applicable to the case of higher pressure.

[0119] Furthermore, this embodiment can ensure that the diaphragm will not be damaged due to excessive deformation when subjected to pressure by calculating the maximum allowable strain of the diaphragm, thereby ensuring the long-term stability and reliability of the sensor.

[0120] Furthermore, the results of this embodiment are intuitive, and the results such as the relationship between the capacitance change and the pressure obtained by calculation are intuitive and easy to understand, and can be conveniently used for performance evaluation and fault diagnosis of the sensor.

[0121] Furthermore, this method can guide the design of ceramic capacitor pressure sensors. By calculating parameters such as capacitance and capacitance sensitivity, the structural parameters and performance parameters of the sensor can be optimized, thereby improving the measurement accuracy and stability of the sensor.

[0122] Furthermore, by evaluating the relationship between the deformation behavior of the diaphragm and the change in capacitance, this method can determine whether the sensor will be damaged or fail when subjected to pressure, thereby ensuring the structural integrity of the sensor.

[0123] Furthermore, this method is not only applicable to marine ceramic capacitor pressure sensors, but can also be extended to the evaluation of pressure sensors in other fields, and has broad application prospects.

[0124] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for estimating the structural integrity state of a marine ceramic capacitor pressure sensor, characterized in that: The method comprises the following steps: A mathematical model of ceramic capacitor diaphragm is established to describe the deformation behavior of the diaphragm under external pressure and its relationship with the change of capacitance. Conduct basic what-if analysis of the diaphragm; Calculate the deflection of the diaphragm in small deflection deformation and large deflection deformation respectively, and calculate the maximum allowable strain of the diaphragm; Calculate the capacitance and capacitance sensitivity of the pressure sensor, and derive the relationship between the capacitance change and pressure; The structural integrity of the pressure sensor is comprehensively evaluated by combining the deformation behavior of the diaphragm, the maximum allowable strain, and the relationship between capacitance and pressure.

2. The method according to claim 1, characterized in that: The basic assumptions for the diaphragm analysis include: The line segments perpendicular to the mid-surface remain straight lines and are still perpendicular to the deformed mid-surface; The normal stress perpendicular to the mid-plane is relatively small and can be ignored, so only the in-plane stress and deformation need to be considered; Only the deformation of the diaphragm caused by pressure is considered.

3. The method according to claim 1, characterized in that: The deflection calculation of the diaphragm under small deflection deformation is expressed as the following deflection formula: Where d0 is the deflection of the center point of the diaphragm, R is the radius of the diaphragm, and r is the distance from a point on the movable electrode of the diaphragm to the center of the diaphragm.

4. The method according to claim 3, characterized in that: The deflection calculation of the diaphragm under large deflection deformation is expressed as the following deflection formula: Among them, μ is Poisson's ratio, E is Young's elastic modulus, and h is the thickness of the diaphragm.

5. The method according to claim 1, characterized in that The calculation of the maximum allowable strain of the diaphragm includes: The maximum allowable strain of the elastic diaphragm in the event of plastic deformation or cracking is calculated as follows: 。 6. The method according to claim 1, characterized in that The method of calculating the capacitance and capacitance sensitivity of the pressure sensor comprises: In the case of diaphragm deformation, the capacitance calculation of the pressure sensor is expressed as follows: Where C0 is the capacitance value when the pressure is 0, ε0 is the dielectric constant of vacuum, ε a is the relative dielectric constant of air.

7. The method according to claim 6, characterized in that The method of calculating the capacitance and capacitance sensitivity of the pressure sensor comprises: Calculate the sensitivity of the capacitor, expressed as the following formula: 。 8. The method according to claim 1, characterized in that: When establishing the mathematical model, Timoshenko plate and shell theory is used to analyze the deformation of the diaphragm.

9. The method according to any one of claims 1 to 8, characterized in that: Also execute: Use ANSYS software to perform numerical simulation, set the properties of ceramic materials, and simulate the deformation of the diaphragm under different pressure differences; Divide the diaphragm grid to ensure simulation accuracy and analyze the stress and deflection distribution of the diaphragm under different pressures; Adjust simulation parameters and perform multiple simulations to ensure the stability and repeatability of simulation results.

10. The method according to any one of claims 1 to 8, characterized in that: Also execute: Introduce temperature, humidity or other multi-physics factors to analyze their impact on the deformation behavior and capacitance characteristics of ceramic capacitor diaphragms.

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