Strain sensor calibration device with limiting structure and calibration method

Abstract

The application discloses a strain sensor calibration device with a limiting structure and a calibration method, and belongs to the technical field of measuring instruments. The calibration device comprises a vibration isolation platform, a clamping support beam fixed on the vibration isolation platform, upper and lower limiters symmetrically arranged above and below a cantilever beam, and the cantilever beam with one end connected with a piezoelectric ceramic exciter through a thread and the middle part clamped by the limiter. The piezoelectric ceramic exciter penetrates through the clamping support beam and applies displacement excitation with a preset amplitude and frequency to excite the cantilever beam to vibrate. When the deflection of the short beam section of the cantilever beam exceeds the set gap, the limiter is in contact with the short beam section, the nonlinear modulation effect is used to suppress the subharmonic vibration and chaotic motion of the short beam section, so that the main beam section outputs stable periodic deflection response. The application solves the problems of unstable signal and insufficient precision in dynamic calibration, and realizes high-precision dynamic calibration of the strain sensor under the condition of low frequency and large deflection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of measuring instruments, in particular to a strain sensor calibration device with a limiting structure and a calibration method, which is suitable for measuring and analyzing the displacement, deflection, nonlinear response and limiting characteristics of the strain sensor under external excitation or load. BACKGROUND

[0002] As a key device for monitoring the stress state of a structure and outputting strain signals, strain sensors are increasingly widely used in the fields of bridge health monitoring, medical equipment, smart home, etc. Among them, the pasted strain sensor has become the mainstream solution in engineering strain measurement due to its flexible installation, fast frequency response and moderate cost.

[0003] To ensure the accuracy and comparability of strain sensor measurement data, the calibration test link is particularly important. At present, relevant standards at home and abroad have specified the static performance indicators and detection methods of pasted strain sensors, and proposed multiple static calibration methods including the four-point bending beam method, the equal-strength cantilever beam method and the high-precision displacement platform stretching method. These methods have played an important role in verifying the static characteristics of sensors. However, with the increasing complexity of engineering application environment, strain sensors are often under dynamic load and nonlinear vibration conditions in actual work, and it is difficult to accurately reflect their transient response characteristics and frequency characteristics relying solely on static calibration.

[0004] In recent years, researchers have developed various dynamic calibration techniques, such as the impact loading method based on Hopkinson bar, the transient loading method based on drop hammer, the step loading method based on suspended weights and the frequency response method based on vibration table. Although these methods can obtain the response information of sensors under dynamic environment to some extent, they still have problems such as complex experimental devices, insufficient controllability, limited frequency range or low calibration accuracy. Especially under low-frequency, large-deflection and nonlinear vibration conditions, existing devices are difficult to achieve high-precision, low-cost and repeatable dynamic calibration.

[0005] In summary, the existing strain sensor calibration technology still mainly relies on static methods, and dynamic calibration technology is not mature, lacking a dynamic calibration device that can balance high precision, wide dynamic range and effectively respond to low-frequency nonlinear response. Therefore, it is urgent to develop a strain sensor calibration device with a limiting structure and a calibration method, which can realize accurate calibration and performance testing of pasted strain sensors under dynamic working conditions through reasonable structural design and loading method, to meet the urgent needs of dynamic measurement in various fields. SUMMARY

[0006] The purpose of the present application is to provide a strain sensor calibration device with a limiting structure and a calibration method to solve the above technical problems existing in the prior art.

[0007] To achieve the above object, in one aspect, the present application provides a strain sensor calibration device with a limiting structure, comprising: a vibration isolation platform, on which a clamping support beam is fixed; a limiter, which is fixed to one end of the clamping support beam and comprises an upper limiter and a lower limiter; a cantilever beam, the left end of which is connected with a piezoelectric ceramic actuator through a thread, the middle part of which is clamped by the upper limiter and the lower limiter, and the right end of which is a free end; the left end of the cantilever beam to the limiter region is a short beam section, and the rest is a main beam section; the upper limiter and the lower limiter are symmetrically arranged above and below the cantilever beam to limit the displacement limit of the cantilever beam vibration; the piezoelectric ceramic actuator is connected with the cantilever beam through the clamping support beam, used for applying displacement excitation with a preset amplitude and frequency; when the deflection of the short beam section of the cantilever beam exceeds the set gap, the limiter and the short beam section come into contact, so that the main beam section of the cantilever beam outputs a stable periodic deflection response; a reference measurement device acquires and monitors the motion trajectory of the free end of the main beam section of the cantilever beam.

[0008] Further, the gap between the upper limiter and the lower limiter and the surface of the cantilever beam is adjustable, and the initial set gap is 30μm.

[0009] Further, the free end of the cantilever beam is provided with a sensor mounting platform, which is used to fix the micro-displacement or micro-strain sensor to be calibrated.

[0010] Further, the clamping support beam is supported and fixed on the vibration isolation platform through a base connecting beam.

[0011] Further, the base connecting beam is bolted with the vibration isolation platform, and the clamping support beam is welded or bolted and fixed on the base connecting beam.

[0012] Further, a pre-tightening force fine adjustment mechanism is provided between the piezoelectric ceramic actuator and the vibration isolation platform.

[0013] Further, the pre-tightening force fine adjustment mechanism comprises an adjusting screw and a fixed nut; the upper end of the adjusting screw is connected with the piezoelectric ceramic actuator, and the lower end is inserted into a flange; the fixed nut is threadedly matched with the adjusting screw, used for adjusting the pre-tightening force and fixing the lower end of the adjusting screw.

[0014] Further, the reference measurement device is a laser displacement sensor.

[0015] In another aspect, the present application also provides a strain sensor calibration method, which uses the strain sensor calibration device with a limiting structure described in any one of the above aspects, and the method comprises the following steps:

[0016] Step one: fix the sensor to be calibrated on the sensor mounting platform at the free end of the cantilever beam, and level the cantilever beam to the symmetric position;

[0017] Step two: drive the piezoelectric ceramic exciter by the external control circuit, apply excitation signal, make the cantilever beam produce periodic vibration;

[0018] Step three: when the short beam segment deflection of the cantilever beam exceeds the set gap, the limit stopper contacts the short beam segment, so that the main beam segment of the cantilever beam outputs stable periodic deflection response;

[0019] Step four: collect the piezoelectric ceramic exciter input signal, sensor output signal and reference measurement device signal;

[0020] Step five: change the excitation parameters, repeat steps two to four, compare the sensor and reference measurement device response curves, and obtain the dynamic sensitivity and frequency characteristics;

[0021] Step six: calculate the dynamic calibration curve based on multiple sets of data, analyze the sensitivity drift, nonlinear error and stability index.

[0022] Compared with the prior art, the present application at least discloses the following beneficial effects:

[0023] The present application provides a stable support foundation through a vibration isolation platform, combines the upper and lower limit stops to fix the support beam, forms a symmetrical limit structure, effectively restricts the displacement limit of the cantilever beam during vibration, avoids signal instability caused by excessive nonlinear deformation, reliably connects one end of the cantilever beam with the piezoelectric ceramic exciter through a thread, sets a sensor mounting platform at the other end, applies a preset amplitude and frequency displacement excitation through the piezoelectric ceramic exciter, excites the cantilever beam to produce periodic vibration response, triggers contact when the limit stopper contacts the short beam segment when the deflection of the cantilever beam exceeds the set gap, forms a segmented smooth nonlinear modulation effect, suppresses the sub-harmonic and chaotic response, ensures that the main beam segment outputs stable and repeatable periodic deflection signals, and the overall structure is compact and reasonable, can realize high-precision and controllable strain sensor calibration under dynamic working conditions, and significantly improves the accuracy and reliability of the calibration results. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 It is a front view of the strain sensor calibration device with a limit structure of the present application.

[0026] Figure 2 It is a top view of the strain sensor calibration device with a limit structure of the present application.

[0027] Figure 3 For Figure 1 local enlarged view at A in the middle;

[0028] Figure 4 for the free end of the cantilever beam main girder section without containing the limiter;

[0029] Figure 5 for the phase trajectory diagram of the free end of the cantilever beam main girder section without containing the limiter;

[0030] Figure 6 for the time domain diagram of the cantilever beam short girder section in the device of the application;

[0031] Figure 7 for the phase trajectory diagram of the cantilever beam short girder section in the device of the application;

[0032] Figure 8 for the time domain diagram of the free end of the cantilever beam main girder section after being modulated by the limiter in the device of the application;

[0033] Figure 9 for the phase trajectory diagram of the free end of the cantilever beam main girder section after being modulated by the limiter in the device of the application.

[0034] In the figure: 1, vibration isolation platform; 2, base connecting beam; 3, clamping support beam; 4, upper limiter; 5, cantilever beam; 6, lower limiter; 7, piezoelectric ceramic exciter; 8, adjusting screw; 9, fixed nut; 10, flange; 11, fastening screw. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0036] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.

[0037] Reference Figures 1 to 3As shown, the embodiment provides a strain sensor calibration device with a limiting structure, which comprises a vibration isolation platform 1, a base connecting beam 2, a clamping support beam 3, an upper limit stopper 4, a cantilever beam 5, a lower limit stopper 6, a piezoelectric ceramic exciter 7, an adjusting screw 8, a fixing nut 9, a flange plate 10 and a fastening screw 11. The strain sensor calibration device is mainly used for high-precision calibration of the pasted strain sensor under dynamic working conditions, and is especially suitable for calibration requirements under low-frequency, large-deflection and nonlinear vibration conditions. The overall structure of the device is compact, the vibration response of the cantilever beam 5 is constrained and modulated by introducing the limit stopper, and the stability and repeatability of the output signal are ensured.

[0038] In the embodiment of the present application, the vibration isolation platform 1 provides stable support and vibration isolation environment for the whole device, and the material thereof is usually stainless steel to ensure the stability of the device under dynamic excitation. The surface of the vibration isolation platform 1 is provided with threaded holes for fixing the base connecting beam 2 and the flange plate 10 by the fastening screws 11. The base connecting beam 2 is fixedly installed on the vibration isolation platform 1 by a plurality of fastening screws 11, and serves to connect and support the upper structure. The material thereof is high-strength aluminum alloy, which not only ensures rigidity but also reduces the overall weight. The clamping support beam 3 is vertically arranged on the base connecting beam 2 and is fixed by welding or bolt connection. The right end of the clamping support beam 3 is fixedly connected with the upper limit stopper 4, and the height thereof is adjustable to adapt to cantilever beams 5 of different sizes.

[0039] The cantilever beam 5 is the core component of the device, one end of which is connected with the piezoelectric ceramic exciter 7 through threads, the middle part is clamped by the upper limit stopper 4 and the lower limit stopper 6, and the other end is a free end. The material of the cantilever beam 5 is preferably spring steel or stainless steel, which has good elasticity and fatigue strength. The free end is provided with a sensor mounting platform for fixing the micro-displacement or micro-strain sensor to be calibrated.

[0040] Specifically, the upper limit stopper 4 and the lower limit stopper 6 are symmetrically arranged above and below the cantilever beam 5 and are fixed by the clamping support beam 3 and the base connecting beam 2 respectively. The gap between the limit stopper (collectively referred to as the upper limit stopper 4 and the lower limit stopper 6) and the surface of the cantilever beam 5 is adjustable (initially set to 30μm), which is used to limit the upper and lower limit positions of the short beam segment vibration of the cantilever beam 5. When the deflection of the short beam segment of the cantilever beam 5 exceeds the set gap, the limit stopper restricts its movement by contact to avoid excessive nonlinear deformation.

[0041] The piezoelectric ceramic exciter 7 is installed near the left end of the cantilever beam 5 and is adjustably connected with the cantilever beam 5 through threads and is connected with an external control circuit. Its function is to apply displacement excitation of adjustable amplitude and frequency to the cantilever beam 5 to excite the periodic vibration response of the cantilever beam 5.

[0042] The adjusting screw 8 and the fixed nut 9 are arranged below the piezoelectric ceramic exciter 7, and the adjusting screw 8 and the fixed nut 9 together constitute a pre-tightening force fine adjustment mechanism, which is used for fine adjustment of the mounting position and the pre-tightening force between the exciter and the cantilever beam 5, and ensures the accuracy and stability of excitation transmission.

[0043] The flange plate 10 is connected with the piezoelectric ceramic exciter 7 through the adjusting screw 8, and is fixed on the vibration isolation platform 1 through the fastening screw 11, and plays a supporting and positioning role.

[0044] The fastening screw 11 is eight in total, which is an internal hexagonal cylindrical head screw, and is used for fixing the base connecting beam 2 and the flange plate 10 on the vibration isolation platform 1, and ensures the rigid connection of the overall structure.

[0045] The device also comprises a reference measurement device, which is used for acquiring and monitoring the motion trajectory of the free end of the main beam section of the cantilever beam. In the initial use, the reference measurement device is used to acquire the motion trajectory of the free end of the main beam section of the cantilever beam 5; in the later use process, the reference measurement device is used to monitor the motion trajectory of the free end of the main beam section of the cantilever beam 5. If the motion trajectory of the free end of the main beam section of the cantilever beam 5 deviates from the motion trajectory recorded at the initial time by more than a set threshold value after a period of motion, it is necessary to replace the stopper or the cantilever beam 5.

[0046] In one specific embodiment, the cantilever beam 5 in the device is made of aluminum alloy material, the Young's modulus of which is 70 GPa, and the density is 2700 kg / m 3 . The left end of the cantilever beam 5 to the stopper region is set as a short beam section, the length of which is 0.1 m; the stopper to the free end is set as a main beam section, the length of which is 0.4 m, the width of the main beam section is 0.02 m, and the thickness of the main beam section is 0.005 m. The stopper is made of rigid metal material and is subjected to quenching and hardening treatment, and the initial gap is set to 30 μm, the contact stiffness of which is 1×10 12 N / m, which can generate instantaneous nonlinear contact force when large deflection occurs in the short beam section, so as to realize the truncation and modulation of the nonlinear vibration. The maximum excitation amplitude of the piezoelectric ceramic exciter is 100 μm, and the excitation frequency is set to 0.9 times the short beam fundamental frequency.

[0047] It should be understood that the function of the stopper to modulate the nonlinear vibration is not universal. Through a large number of numerical simulations and experiments by the applicant, it is found that even for the same cantilever beam 5, the stopper needs to meet four conditions to have the function of modulating the nonlinear vibration. Condition one, the main beam section and the short beam section are an integral structure, and the cross sections and the materials are the same; condition two, the main beam section is obviously longer than the short beam section; condition three, the stopper needs to be subjected to hardening treatment, that is, the contact stiffness reaches a preset value; condition four, the natural frequency of the main beam section is much lower than the natural frequency of the short beam section. In the embodiment of the application, the natural frequency of the main beam section is about 29 Hz, and the natural frequency of the short beam section is about 466 Hz.

[0048] The working principle and technical effects of the device of the embodiment are as follows:

[0049] The working principle of the calibration device is based on a cantilever beam 5-piezoelectric ceramic excitation-limiting coupling structure, aiming to realize high-precision calibration of a strain sensor under dynamic working conditions. In operation, first, the micro displacement sensor to be calibrated is fixed on the sensor mounting platform at the free end of the main beam section of the cantilever beam 5, and the pre-tightening force of the piezoelectric ceramic exciter 7 and the cantilever beam 5 is adjusted through the adjusting screw 8 and the fixed nut 9 to ensure that the cantilever beam 5 is in a symmetrical position under free vibration. Subsequently, the piezoelectric ceramic exciter 7 is driven by an external control circuit to input a sine displacement signal with a set amplitude and frequency to excite the cantilever beam 5 to generate periodic vibration response. At this time, the short beam section of the cantilever beam 5 drives the main beam section to form a deflection response under excitation; when the deflection exceeds the gap (such as 30 μm) set by the upper limiting stopper 4 and the lower limiting stopper 6, the cantilever beam 5 contacts the limiting stopper, and the non-linear modulation action suppresses the sub-harmonic and chaotic vibration of the short beam section, avoiding excessive non-linear deformation, thereby ensuring that the main beam section outputs stable periodic deflection signals. Under the stable constraint of the limiting stopper, the input signal of the piezoelectric ceramic exciter 7, the sensor output signal and the measurement value of the reference measurement device (such as a laser displacement sensor) are recorded synchronously by a data acquisition module, the acquisition process is repeated by changing the excitation parameters, and the response curves of the sensor and the reference measurement device are compared to obtain the dynamic sensitivity and frequency characteristics. Finally, based on multiple sets of data, the dynamic calibration curve of the sensor is calculated by using the least square method or fitting algorithm, the sensitivity drift, non-linear error and other indicators are analyzed, and dynamic calibration is completed.

[0050] The device of the embodiment effectively suppresses the sub-harmonic and chaotic response of the short beam section of the cantilever beam 5 through the introduction of the limiting stopper, ensures the periodicity and stability of the output of the main beam section, and thus improves the accuracy and reliability of dynamic calibration. At the same time, the device has compact structure and is easy to integrate, and is suitable for high-precision dynamic calibration of micro displacement sensors in laboratories or industrial sites.

[0051] The embodiment of the present application also proposes a strain sensor calibration method using the strain sensor calibration device with a limiting structure described in the above embodiment, which comprises the following steps:

[0052] Step one, sensor installation and initial leveling

[0053] The strain sensor to be calibrated is fixed on the sensor mounting platform at the free end of the cantilever beam 5; the piezoelectric ceramic exciter 7 is brought into close contact with the surface of the cantilever beam 5 by rotating the adjusting screw 8 and the fixed nut 9, and the cantilever beam 5 is adjusted to a symmetrical position under free vibration to ensure that there is no bias load in the initial state.

[0054] Step two, applying dynamic excitation

[0055] The piezoelectric ceramic exciter 7 is driven by an external control circuit, and a sine displacement signal with a set amplitude and frequency is input to excite the cantilever beam 5 to generate periodic vibration; at this time, the short beam section of the cantilever beam 5 drives the main beam section to form a stable deflection response under the excitation action.

[0056] Step three, triggering the limit contact

[0057] When the deflection of the cantilever beam 5 exceeds the gap (such as 30 μm) set by the upper limit stopper 4 and the lower limit stopper 6, the cantilever beam 5 contacts the limit stopper; the limit stopper restricts the motion amplitude of the short beam section to suppress the sub-harmonic and chaotic response, and ensures that the main beam section outputs a periodic stable deflection signal.

[0058] Step four, collecting dynamic response signals

[0059] Under the stable restriction of the limit stopper, the following signals are recorded synchronously by a data acquisition module:

[0060] Signal one: the input excitation signal of the piezoelectric ceramic exciter 7;

[0061] Signal two: the output signal of the strain sensor installed at the free end of the cantilever beam 5;

[0062] Signal three: the actual deflection value measured by a reference measuring device (such as a laser displacement sensor).

[0063] Step five, repeating excitation and signal comparison

[0064] The amplitude or frequency of the piezoelectric excitation signal is changed, and steps two to four are repeated to collect multiple sets of data under different dynamic conditions; the response curves of the strain sensor output signal and the reference measuring device are compared to obtain the dynamic sensitivity and frequency response characteristics of the sensor.

[0065] Step six, determining the calibration result

[0066] Based on the comparison data under multiple excitation conditions, the least square method or fitting algorithm is used to calculate the dynamic calibration curve of the sensor, analyze the sensitivity drift, nonlinear error and stability index, and complete the dynamic calibration process.

[0067] The method effectively suppresses the nonlinear instability phenomenon in the vibration process of the cantilever beam 5 by introducing the limit stopper, ensures the repeatability and accuracy of the dynamic calibration signal, and is especially suitable for high-precision calibration requirements under low-frequency, large-deflection and nonlinear vibration conditions.

[0068] As shown in Figure 4 and Figure 5 , the method comprises the following steps: Figure 4The displacement-time response of the free end of the cantilever beam in the conventional calibration device without the position limiter is shown. It can be seen that the displacement of the free end changes with time and presents amplitude drift, unstable response and other characteristics, and it is difficult to maintain ideal periodic motion state. Figure 5 The corresponding phase trajectory diagram is shown. The trajectory presents obvious nonlinearity and sub-harmonic component, which shows that the conventional calibration device is difficult to avoid the nonlinear vibration problem of the cantilever beam under dynamic working condition, thereby leading to unstable output stress environment, which is not conducive to realize high repeatability and high-precision dynamic calibration.

[0069] As shown in Figure 6 and Figure 7 , Figure 6 The time-domain response of the short beam section of the cantilever beam 5 in the device of the application without modulation by the position limiter under dynamic excitation is shown. The short beam section presents strong nonlinear characteristics under the action of excitation, and its displacement changes irregularly with time, and the overall response presents complex period-doubling or chaotic motion. Figure 7 The phase trajectory diagram of the short beam section is shown. It can be seen that the trajectory distribution presents obvious dense intersection, which further verifies that the short beam section presents obvious uncontrollable nonlinear vibration phenomenon when the position limiter is not used for modulation. If the modulation is not performed, the nonlinear disturbance will be transmitted to the main beam section, affecting the stability of the calibration output.

[0070] As shown in Figure 8 and Figure 9 , Figure 8 The displacement-time response of the main beam section of the cantilever beam 5 after modulation by the position limiter of the application is shown. It can be seen that the response of the main beam section is significantly stabilized under the action of the position limiter, and presents periodic motion with constant amplitude and clear structure, which shows that the position limiter can effectively suppress the chaotic or period-doubling vibration of the short beam section, thereby ensuring that the vibration signal transmitted to the main beam section presents regular and controllable periodicity. Figure 9 The phase trajectory diagram of the main beam section is shown. The trajectory presents regular and closed ring structure, which shows that the main beam section has restored periodic vibration state, and the dynamic output signal has high stability and high repeatability.

[0071] In the drawings Figures 4 to 9 By comparing and analyzing the response of the free end of the cantilever beam in the conventional calibration device, the response of the short beam section in the device of the application without modulation and the response of the main beam section after modulation by the position limiter, the core role of the position limiter of the device of the application in suppressing nonlinear vibration and stabilizing output signal is intuitively shown.

[0072] In the description of the present application, it needs to be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0073] The above-described embodiments are only to describe the preferred modes of the present application, and not to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A strain sensor calibration device with a stop structure, characterized by, The utility model relates to a vibration isolation platform, and it comprises the following: A vibration isolation platform (1) is provided with a clamping support beam (3) fixed thereon; A position limiter is fixed to one end of the clamping support beam (3) and comprises an upper position limiter (4) and a lower position limiter (6); A cantilever beam (5) is connected to a piezoelectric ceramic exciter (7) at the left end through a thread, is clamped by the upper position limiter (4) and the lower position limiter (6) in the middle, and has a free end at the right end; The left end of the cantilever beam (5) to the position limiter region is a short beam section, and the rest is a main beam section, the main beam section and the short beam section are an integral structure, and the natural frequency of the main beam section is much lower than that of the short beam section; The piezoelectric ceramic exciter (7) is connected with the cantilever beam (5) through the clamping support beam (3) and is used for applying displacement excitation with preset amplitude and frequency; the stopper is made of rigid metal material and is quenched and hardened, and the contact stiffness when the stopper contacts with the short beam section of the cantilever beam (5) is not less than 1×10 12 N / m. The upper position limiter (4) and the lower position limiter (6) are symmetrically arranged above and below the cantilever beam (5) to limit the displacement limit of the vibration of the cantilever beam (5); When the deflection of the short beam section of the cantilever beam (5) exceeds the set gap, the position limiter and the short beam section come into contact, the short beam section is truncated and modulated through instantaneous nonlinear contact force, and the main beam section of the cantilever beam (5) outputs a stable periodic deflection response; 2. The strain sensor calibration device with a stop structure according to claim 1, wherein, A reference measuring device is used to acquire and monitor the motion trajectory of the free end of the main beam section of the cantilever beam (5).

3. The strain sensor calibration device with a stop structure according to claim 1, wherein, The gap between the upper position limiter (4) and the lower position limiter (6) and the surface of the cantilever beam (5) is adjustable, and the initial set gap is 30 microns.

4. The strain sensor calibration device with a stop structure according to claim 1, wherein, The free end of the cantilever beam (5) is provided with a sensor mounting platform, and the sensor mounting platform is used to fix a micro-displacement or micro-strain sensor to be calibrated.

5. The strain sensor calibration device with a stop structure according to claim 4, wherein, The clamping support beam (3) is supported and fixed on the vibration isolation platform (1) through a base connecting beam (2).

6. The strain sensor calibration device with a stop structure according to claim 1, wherein, The base connecting beam (2) is bolted to the vibration isolation platform (1), and the clamping support beam (3) is welded or bolted to the base connecting beam (2).

7. The strain sensor calibration device with a stop structure according to claim 6, characterized in that, A pre-tightening force fine adjustment mechanism is arranged between the piezoelectric ceramic exciter (7) and the vibration isolation platform (1).

8. The strain sensor calibration device with a stop structure according to claim 1, wherein, The pre-tightening force fine adjustment mechanism comprises an adjusting screw (8) and a fixed nut (9), the upper end of the adjusting screw (8) is connected to the piezoelectric ceramic exciter (7), the lower end of the adjusting screw (8) is inserted into a flange (10), and the fixed nut (9) is threadedly connected to the adjusting screw (8) to adjust the pre-tightening force and fix the lower end of the adjusting screw (8).

9. The strain sensor calibration device with a stop structure according to claim 8, wherein, The piezoelectric ceramic exciter (7) is threadedly connected to the cantilever beam (5).

10. A strain sensor calibration method using the strain sensor calibration apparatus with a limiting structure according to any one of claims 1 to 9, characterized by, The reference measuring device is a laser displacement sensor. The method comprises the following steps: Step one: fix the sensor to be calibrated on the sensor mounting platform at the free end of the cantilever beam (5), and level the cantilever beam (5) to the symmetric position; Step two: drive the piezoelectric ceramic exciter (7) through an external control circuit to apply an excitation signal, so that the cantilever beam (5) generates periodic vibration; Step three: when the deflection of the short beam section of the cantilever beam (5) exceeds the set gap, the position limiter and the short beam section come into contact, so that the main beam section of the cantilever beam (5) outputs a stable periodic deflection response; Step four: collect the input signal of the piezoelectric ceramic exciter (7), the output signal of the sensor, and the signal of the reference measuring device; Step five: repeat steps two to four by changing the excitation parameters, compare the response curves of the sensor and the reference device, and obtain the dynamic sensitivity and frequency characteristics. Step six: Based on multiple sets of data to calculate dynamic calibration curve, analyze sensitivity drift, non-linear error and stability index.

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