Strain sensor with ultrahigh water pressure resistance and measuring method

Abstract

The invention discloses a strain sensor with ultrahigh water pressure resistance and a measuring method, and the strain sensor comprises a vibrating wire strain sensor which is disposed in a housing, and the fixed end of the vibrating wire strain sensor is connected with one end of the housing to form a first waterproof isolation region; two ends of the free telescopic part are respectively connected with the measuring end of the vibrating wire measuring unit and the other end of the shell to form a second waterproof isolation area; and the vibrating wire strain sensor, the shell and the free telescopic component form a strain sensor.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engineering structure strain monitoring under high water pressure environment, and more particularly relates to a strain sensor with super-high water pressure resistance and a measuring method. BACKGROUND

[0002] In the fields of water conservancy projects, deep sea exploration, oil and gas exploitation, etc., long-term monitoring of engineering structure strain under high water pressure environment is often required. Due to the advantages of strong stability and resistance to harsh environment, the vibrating wire sensor has become one of the core monitoring devices in such scenarios.

[0003] Such engineering is in a special high water pressure environment, and the vibrating wire strain sensor used also has the adaptability requirement of high pressure resistance. The conventional vibrating wire strain sensor, as shown in the figure, is sealed by O-shaped waterproof rubber ring for waterproof, and can resist water pressure of 5 MPa at most, but the waterproof performance cannot be completely guaranteed due to the unstable quality of the O-shaped waterproof rubber ring. Figure 3

[0004] In addition, in the prior art, the vibrating wire strain sensor often uses linear temperature compensation method for frequency correction, that is, it is assumed that the frequency drift is linearly related to the temperature, and the second-order strain effect and the lagging influence of temperature change rate on the vibrating wire frequency are ignored.

[0005] Therefore, a technical scheme is needed to solve the above technical problems. SUMMARY

[0006] To solve the above technical problems, the application provides a strain sensor with super-high water pressure resistance, comprising: a vibrating wire strain sensor arranged in the shell, the fixed end of which is connected with one end of the shell and forms a first waterproof isolation zone; a free expansion component, the two ends of which are respectively connected with the measuring end of the vibrating wire measuring unit and the other end of the shell and form a second waterproof isolation zone; the vibrating wire strain sensor, the shell and the free expansion component form a strain sensor.

[0007] Further, the fixed end is connected with one end of the shell by welding method and forms a first waterproof isolation zone; the two ends of the free expansion component are respectively connected with the measuring end of the vibrating wire measuring unit and the other end of the shell by welding method and form a second waterproof isolation zone.

[0008] Further, the free expansion component is a bellows.

[0009] Further, the inner cavity of the free expansion component is coaxially arranged with the vibrating wire strain sensor.

[0010] Further, the shell is a metal pipe. ​

[0011] The application further provides a measurement method based on the strain sensor with super-high water pressure resistance, comprising: obtaining an actual vibrating string frequency of a historical measurement, a corresponding historical actual vibrating string strain and a corresponding internal shell temperature, setting a vibrating string drift model, taking the historical actual vibrating string strain as training data, and calculating a corresponding predicted vibrating string frequency; fitting the vibrating string drift model according to the actual vibrating string frequency, so that the predicted vibrating string frequency is less than a preset error threshold value from the actual vibrating string frequency, and training of the vibrating string drift model is completed, wherein one weight in the vibrating string drift model is fitted; taking the vibrating string strain as a result, inverting the vibrating string drift model, inputting the obtained real-time vibrating string frequency and real-time internal shell temperature into the inverted vibrating string drift model, and thus obtaining a corresponding vibrating string strain.

[0012] Further, the vibrating string drift model comprises: , wherein, is a time at which the vibrating string frequency is , is an initial reference frequency, is a first weight of the drift model, is a vibrating string strain at a time , is a second weight of the drift model, is a third weight of the drift model, is a fourth weight of the drift model, is a fifth weight of the drift model, is a sixth weight of the drift model, is a seventh weight of the drift model, is a first derivative of the internal shell temperature at a time , is an eighth weight of the drift model, is a second derivative of the internal shell temperature at a time , is a ninth weight of the drift model, is a thermal hysteresis function taking the internal shell temperature and the first derivative of the internal shell temperature as parameters, is an internal shell temperature at a time .

[0013] Further, the thermal hysteresis function taking the internal shell temperature and the first derivative of the internal shell temperature as parameters comprises: , wherein, is the thermal conduction delay time inside the housing, is the time is the temperature inside the housing at time is the calibration reference temperature, is the first derivative of the temperature inside the housing at time .

[0014] Further, an ultrasonic sensor is arranged inside the housing and / or the free expansion component for emitting and receiving ultrasonic waves. The ultrasonic sensor emits ultrasonic waves to the housing and / or the free expansion component in cycles, thereby detecting the sealing condition of the housing and / or the free expansion component.

[0015] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects: The end of the vibrating string strain sensor is connected with the steel pipe by welding at the joint, and the other end is the measuring end of the vibrating string strain sensor, which is required to be free to expand, so a section of corrugated pipe is sleeved here, and the two ends of the corrugated pipe are welded on the measuring end and the steel pipe respectively, and finally the ultrahigh water pressure resistant strain sensor is designed, which is completely sealed and can resist water pressure of more than 20MPa through test.

[0016] In addition, the measurement method of the present application introduces a convolution form of thermal hysteresis function, so that the vibrating string drift model not only depends on the instantaneous temperature, but also considers the hysteresis effect of temperature change history on frequency, which can effectively reduce the frequency drift error in the environment of rapid temperature change or periodicity. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of embodiment 1 of the present application; Figure 2 is a method flowchart of embodiment 2 of the present application; Figure 3 is a schematic diagram of the existing strain sensor. DETAILED DESCRIPTION

[0018] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings in the specification and specific embodiments.

[0019] The method provided by the present application can be implemented in a terminal environment, which can include one or more of the following components: a processor, a storage medium and a display screen. Among them, the storage medium stores at least one instruction, which is loaded and executed by the processor to realize the method described in the following embodiments.

[0020] The processor can include one or more processing cores. The processor connects various parts within the terminal with various interfaces and lines, performs various functions of the terminal and processes data by running or executing instructions, programs, code sets or instruction sets stored in the storage medium, and calling data stored in the storage medium.

[0021] The storage medium can include a random access memory (RAM) and can also include a read-only memory (ROM). The storage medium can be used to store instructions, programs, codes, code sets or instructions.

[0022] The display screen is used to display the user interface of each application program.

[0023] In addition, those skilled in the art can understand that the structure of the terminal described above does not constitute a limitation on the terminal, and the terminal can include more or fewer components, or combine certain components, or different component arrangements. For example, the terminal also includes radio frequency circuitry, input units, sensors, audio circuitry, power supplies, and other components, which are not described here.

[0024] Embodiment 1 As shown in Figure 1 The present embodiment proposes a strain sensor with super-high water pressure resistance, comprising: A vibrating wire strain sensor is arranged inside the shell, and the fixed end is connected to one end of the shell to form a first waterproof isolation zone; Specifically, the fixed end is connected to one end of the shell by welding to form a first waterproof isolation zone; A free expansion component is connected to the measuring end of the vibrating wire measuring unit and the other end of the shell to form a second waterproof isolation zone.

[0025] Specifically, the two ends of the free expansion component are connected to the measuring end of the vibrating wire measuring unit and the other end of the shell by welding to form a second waterproof isolation zone.

[0026] Specifically, the free expansion component is a corrugated pipe.

[0027] Specifically, the inner cavity of the free expansion component is coaxially arranged with the vibrating wire strain sensor.

[0028] Specifically, the shell is a metal pipe.

[0029] The vibrating wire strain sensor, the shell and the free expansion component form a strain sensor.

[0030] Embodiment 2 As shown in Figure 2As shown, the embodiment proposes a measurement method of the strain sensor with ultra-high water pressure resistance based on the embodiment 1, comprising: Step 101, acquiring the actual vibrating string frequency of the historical measurement, the corresponding historical actual vibrating string strain and the corresponding shell inner temperature, setting the vibrating string drift model, taking the historical actual vibrating string strain as the training data, and calculating the corresponding predicted vibrating string frequency; Step 102, fitting the vibrating string drift model according to the actual vibrating string frequency, so that the predicted vibrating string frequency is less than the actual vibrating string frequency by a preset error threshold, and the training of the vibrating string drift model is completed, wherein the weights in the vibrating string drift model are fitted; Specifically, the vibrating string drift model comprises: , Wherein, is the vibrating string frequency at time , is the initial reference frequency, is the first weight of the drift model, is the vibrating string strain at time , is the second weight of the drift model, is the third weight of the drift model, is the fourth weight of the drift model, is the fifth weight of the drift model, is the sixth weight of the drift model, is the seventh weight of the drift model, is the first derivative of the shell inner temperature at time , is the eighth weight of the drift model, is the second derivative of the shell inner temperature at time , is the ninth weight of the drift model, is the thermal hysteresis function with the shell inner temperature and the first derivative of the shell inner temperature as parameters, is the shell inner temperature at time .

[0031] Preferably, the embodiment normalizes the physical parameters (such as the shell inner temperature , the vibrating string strain at time , the first derivative of the shell inner temperature , the second derivative of the shell inner temperature at time ) in the vibrating string drift model. ​​​

[0032] Preferably, the least squares method is used to... The first weight of the drift model, The second weight of the drift model The third weight of the drift model The fourth weight of the drift model The fifth weight of the drift model The sixth weight of the drift model The seventh weight of the drift model The eighth weight of the drift model The ninth weight of the drift model is used for fitting.

[0033] Specifically, the temperature inside the casing The first derivative of the temperature inside the shell thermal hysteresis function as a parameter include: , in, This is the delay time for heat conduction inside the casing. For time The internal temperature of the casing at that time To calibrate the reference temperature, For time The first derivative of the temperature inside the outer shell at that time.

[0034] Step 103: Using the vibrating wire strain as the result, the vibrating wire drift model is inverted. The obtained real-time vibrating wire frequency and real-time internal temperature of the shell are input into the inverted vibrating wire drift model to obtain the corresponding vibrating wire strain.

[0035] Specifically, an ultrasonic sensor is installed inside the housing and / or freely expandable parts to emit and receive ultrasonic waves; The ultrasonic sensor periodically emits ultrasonic waves to the housing and / or freely expandable parts to detect the sealing condition of the housing and / or freely expandable parts.

[0036] Preferably, based on the echo information received by the ultrasonic sensor, a comprehensive health index for the housing and / or freely expandable components is calculated, specifically including: , in, For time The overall health index of the outer casing and / or freely expandable components reflects the sealing integrity status, ranging from 0 to 1, with closer to 1 indicating better sealing. An alarm is triggered if the index falls below a set threshold. The steepness of the logistic slope is such that a larger slope results in more sensitive alarm differentiation (faster threshold response). The weights of the amplitude sub-index, For time Time amplitude sub-index, The weights of the time difference sub-index, For time Time difference sub-index The weights of the phase sub-index, For time Time phase sub-index, It is the midpoint of the logistic function, belonging to 0–1, and is usually taken as 0.7–0.8.

[0037] Calculation time Time Amplitude Sub-index include: , in, This is the amplitude sensitivity coefficient; the larger the coefficient, the more sensitive the signal, and the more drastic the response to small amplitude decays. The initial echo amplitude, For time Time echo amplitude, The amplitude exponent controls the steepness of the curve of the exponential function, and can usually be set to 1.5–3.

[0038] Calculation time Time Difference Sub-index include: , in, This is the time-difference sensitivity coefficient, used to adjust the sensitivity of detecting changes in cracks or cavities. For time Round-trip time of echo, This is the initial round-trip time. For time zone index, similar to Adjust the curvature.

[0039] Calculation time Time phase sub-index include: , in, This is the phase sensitivity coefficient; the larger the coefficient, the faster the sensitivity decreases with small phase changes. For time Time echo phase, For the initial phase, This is the midpoint of the logistic regression.

[0040] Time Time Amplitude Sub-index ,time Time Difference Sub-index ,time Time phase sub-index The physical parameters are normalized.

[0041] Preferably, when all sub-indices are close to 1, The closer to 1, the healthier and more airtight the seal. If the pressure is below the acceptable threshold, it indicates that the seal is not up to standard, and an alarm message will be issued to remind the construction personnel that the current ultra-high water pressure strain sensor needs to be replaced or repaired.

[0042] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0043] In the several embodiments provided by this invention, it should be understood that the disclosed technical content can be implemented in other ways. The system embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, indirect coupling or communication connection between units or modules, and may be electrical or other forms.

[0044] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0045] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0046] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, optical disks, and other media capable of storing program code.

[0047] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A strain sensor with ultra-high water pressure resistance, characterized in that, include: The vibrating wire strain sensor, which is installed inside the housing, has its fixed end connected to one end of the housing to form a first waterproof isolation zone; The freely telescopic component has its two ends connected to the measuring end of the vibrating wire measuring unit and the other end of the outer shell, respectively, forming a second waterproof isolation zone; A strain sensor consists of a vibrating wire strain sensor, a housing, and freely expandable components.

2. The ultra-high water pressure resistant strain sensor as described in claim 1, characterized in that, The fixed end is connected to one end of the outer shell by welding to form the first waterproof isolation zone; The two ends of the free-expanding component are respectively connected to the measuring end of the vibrating wire measuring unit and the other end of the outer shell by welding to form a second waterproof isolation zone.

3. The ultra-high water pressure resistant strain sensor as described in claim 1, characterized in that, The freely expandable component is a bellows.

4. The ultra-high water pressure resistant strain sensor as described in claim 1, characterized in that, The inner cavity of the freely expandable component is coaxially aligned with the vibrating wire strain sensor.

5. The ultra-high water pressure resistant strain sensor as described in claim 1, characterized in that, The outer shell is a metal tube.

6. A measurement method based on the ultra-high water pressure resistant strain sensor according to any one of claims 1-5, characterized in that, include: Obtain the actual vibrating wire frequency, the corresponding actual vibrating wire strain, and the corresponding internal temperature of the shell from historical measurements. Set up the vibrating wire drift model, use the historical actual vibrating wire strain as training data, and calculate the corresponding predicted vibrating wire frequency. Based on the actual vibrating string frequency, the vibrating string drift model is fitted to make the predicted vibrating string frequency less than the actual vibrating string frequency by a preset error threshold, thus completing the training of the vibrating string drift model. In this process, the weights in the vibrating string drift model are fitted. Using the vibrating wire strain as the result, the vibrating wire drift model is inverted. The obtained real-time vibrating wire frequency and real-time internal temperature of the shell are input into the inverted vibrating wire drift model to obtain the corresponding vibrating wire strain.

7. The measurement method as described in claim 6, characterized in that, The vibrating wire drift model includes: ， in, For time Temperature inside the casing The frequency of the vibrating string below, The initial reference frequency, As the first weight of the drift model, For time Strain of vibrating string at time As the second weight of the drift model, As the third weight in the drift model, As the fourth weight in the drift model, This is the fifth weight in the drift model. As the sixth weight in the drift model, This is the seventh weight in the drift model. For time The first derivative of the temperature inside the outer shell at that time. This is the eighth weight in the drift model. For time The second derivative of the temperature inside the outer shell at that time. This is the ninth weight in the drift model. Temperature inside the casing The first derivative of the temperature inside the shell Thermal hysteresis function as a parameter For time The internal temperature of the outer casing at that time.

8. The measurement method as described in claim 7, characterized in that, Internal temperature of the casing The first derivative of the temperature inside the shell thermal hysteresis function as a parameter include: ， in, This is the delay time for heat conduction inside the casing. For time The internal temperature of the casing at that time To calibrate the reference temperature, For time The first derivative of the temperature inside the outer shell at that time.

9. The measurement method as described in claim 6, characterized in that, An ultrasonic sensor is installed inside the housing and / or the freely expandable parts for emitting and receiving ultrasonic waves; The ultrasonic sensor periodically emits ultrasonic waves to the housing and / or freely expandable parts to detect the sealing condition of the housing and / or freely expandable parts.

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