A calibration device for adhesive optical fiber strain gauge

Abstract

The present invention provides a calibration device for adhesive-type optical fiber strain gauges, comprising a support column, an equal-strength beam, a force load application unit, and an angle adjustment unit. The equal-strength beam comprises a fixed end and a free end, and is fixed to the support column via the fixed end. The equal-strength beam is used to support the optical fiber strain gauge so that the optical fiber strain gauge is fitted onto the equal-strength beam. The force load application unit is connected to the free end of the equal-strength beam and is used to apply a force load to the equal-strength beam. The angle adjustment unit is connected to the support column and is used to adjust the angle between the support column and the horizontal plane so that the direction of the force load applied by the force load application unit is perpendicular to the equal-strength beam. The technical solution of the present invention is applied to solve the technical problems in the prior art of calibration devices, such as the lack of equal-strength relationships and large calibration errors when the test beam undergoes large deformation.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber strain gauges, and in particular to a calibration device for adhesive optical fiber strain gauges. Background Art

[0002] An adhesive fiber optic strain gauge is a strain measurement instrument that is fixed to the object being measured using a specific connection method (usually adhesive bonding). It measures the strain of the object by synchronously deforming with it. Due to its advantages such as immunity to electromagnetic interference, ease of reuse, and high-temperature resistance, adhesive fiber optic strain gauges are currently widely used for stress and strain measurement in a wide range of fields, including civil engineering, aviation, aerospace, and shipbuilding.

[0003] To improve the measurement accuracy of adhesive fiber optic strain gauges, they usually need to be calibrated. Currently, the calibration of adhesive fiber optic strain gauges mainly involves attaching them to a test beam, applying a force load to the free end of the test beam, and completing the calibration of relevant parameters by comparing and analyzing the stress measurement value output by the adhesive fiber optic strain gauge with the theoretical strain value of the test beam. However, traditional test beams can only maintain an equal strength relationship when measuring small strains within 2000με. When the strain is 5000με or above, the test beam undergoes significant deformation, causing the equal strength relationship to no longer hold, and the calibration accuracy to drop significantly. Therefore, the current calibration device can only achieve small strain calibration within 2000με, and it is difficult to meet the calibration requirements of large strains of 5000με and above. Summary of the Invention

[0004] In order to solve one of the problems existing in the prior art, the present invention provides a calibration device for an adhesive optical fiber strain gauge.

[0005] According to one aspect of the present invention, a calibration device for an adhesive-type optical fiber strain gauge is provided, the calibration device comprising:

[0006] Support columns;

[0007] The equal strength beam includes a fixed end and a free end. The equal strength beam is fixed to the supporting column through the fixed end. The equal strength beam is used to carry the optical fiber strain gauge so that the optical fiber strain gauge is fitted on the equal strength beam.

[0008] A force load applying unit is connected to the free end of the equal strength beam and is used to apply a force load to the equal strength beam;

[0009] An angle adjustment unit is connected to the supporting column and is used to adjust the angle between the supporting column and the horizontal plane so that the direction of the force load applied by the force load applying unit is perpendicular to the equal strength beam.

[0010] Furthermore, the angle adjustment unit includes a guide rail, a slider, a connecting rod and a support plate. The top of the support plate is connected to the bottom of the support column, the end of the support plate is hinged to the end of the guide rail, the slider is set on the guide rail and connected to the bottom of the support plate through a connecting rod. The slider moves along the guide rail to drive the connecting rod to rotate, thereby driving the support plate to rotate in a plane perpendicular to the guide rail.

[0011] Furthermore, the angle adjustment unit further includes a controller and a driver, the driver is connected to the slider, and the angle adjustment unit controls the driver through the controller to drive the slider to move on the guide rail.

[0012] Furthermore, the controller includes a position control module, a speed control module, a position detection feedback module and a speed detection feedback module. The position control module is used to control the moving distance of the slider, the speed control module is used to control the moving speed of the slider, the position detection feedback module is used to detect the position information of the slider and feed the position information back to the position control module, and the speed detection feedback module is used to detect the speed information of the slider and feed the speed information back to the speed control module.

[0013] Furthermore, the driver includes a servo motor, a coupling and a ball screw connected in sequence, the servo motor is connected to the controller, and the ball screw is connected to the slider. The driver drives the ball screw to rotate through the servo motor to drive the slider to move on the guide rail.

[0014] Furthermore, the calibration device also includes a force sensor, which is arranged on the force load applying unit and is used to measure the actual force load value applied to the equal-strength beam by the force load applying unit.

[0015] Furthermore, the force load applying unit includes a weight hanging and a weight, one end of the weight hanging is connected to the free end of the equal strength beam, and the other end contains the weight.

[0016] Furthermore, the force load applying unit includes a traction part, a hollow threaded column and a base. A threaded hole is provided in the base. The hollow threaded column moves in the base by cooperating with the threaded hole. The hollow threaded column is sleeved on the traction part and one end of the traction part is connected to the free end of the equal strength beam, and the other end is limited on the hollow threaded column. The force load applying unit adjusts the force load applied to the traction part by moving the hollow threaded column.

[0017] Furthermore, the material of the equal strength beam is manganese steel.

[0018] Furthermore, the effective length of the equal strength beam is 380 mm, the thickness is 2 mm, the width of the fixed end is 38 mm, and the slope of the effective length section is 0.05.

[0019] By applying the technical solution of the present invention, a calibration device for an adhesive fiber optic strain gauge is provided. The calibration device is configured by placing an equal-strength beam to which the optical fiber strain gauge is attached on a supporting column, configuring a force load application unit at the free end of the equal-strength beam, and configuring an angle adjustment unit to adjust the angle between the supporting column and the horizontal plane, thereby adjusting the angle between the equal-strength beam and the force load so that the angle between the two is always 90°. In this way, the large deformation of the equal-strength beam during large strain measurement can be effectively coped with, ensuring that the equal-strength relationship always holds, thereby ensuring calibration accuracy and improving the calibration range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the embodiments of the present invention, constitute a part of the specification, illustrate the embodiments of the present invention, and together with the description, explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0021] Figure 1 A schematic structural diagram of a calibration device for an adhesive optical fiber strain gauge according to a specific embodiment of the present invention is shown;

[0022] Figure 2 A schematic diagram showing the control and driving principles of a slider and a guide rail provided according to a specific embodiment of the present invention is shown;

[0023] Figure 3 A top view of a constant strength beam provided according to a specific embodiment of the present invention is shown;

[0024] Figure 4 A side view of a constant strength beam provided according to a specific embodiment of the present invention is shown;

[0025] Figure 5 A schematic diagram of the calibration principle of a calibration device for an adhesive optical fiber strain gauge provided according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0029] like Figure 1 As shown, according to a specific embodiment of the present invention, a calibration device for an adhesive optical fiber strain gauge is provided, the calibration device comprising:

[0030] Support column 10;

[0031] The constant strength beam 20 includes a fixed end 21 and a free end 22. The constant strength beam 20 is fixed to the support column 10 via the fixed end 21. The constant strength beam 20 is used to carry the optical fiber strain gauge 30 so that the optical fiber strain gauge 30 is fitted on the constant strength beam 20.

[0032] A force load applying unit 40 , the force load applying unit 40 being connected to the free end 22 of the equal strength beam 20 and being used to apply a force load to the equal strength beam 20 ;

[0033] The angle adjustment unit 50 is connected to the support column 10 and is used to adjust the angle between the support column 10 and the horizontal plane so that the direction of the force load applied by the force load applying unit 40 is perpendicular to the equal strength beam 20.

[0034] The materials of the constant-strength beam 20 and the support column 10 are determined based on calibration requirements. For example, manganese steel can be used for the constant-strength beam 20 to meet calibration requirements for large strains, while aluminum alloy or carbon steel can be used for the support column 10 to meet strength and weight requirements. The mounting method of the support column 10 and the constant-strength beam 20, as well as the installation method of the optical fiber strain gauge 30 on the constant-strength beam 20, are common knowledge in the art and will not be further described here. Typically, the constant-strength beam 20 is perpendicular to the support column 10.

[0035] Using this configuration, a calibration device for adhesive-type optical fiber strain gauges is provided. This calibration device comprises an equal-strength beam 20 with an optical fiber strain gauge 30 attached thereto, disposed on a support column 10, a force load application unit 40 disposed at the free end 22 of the equal-strength beam 20, and an angle adjustment unit 50 configured to adjust the angle between the support column 10 and the horizontal plane. This allows adjustment of the angle between the equal-strength beam 20 and the force load, ensuring that the angle between the two is always 90°. This method effectively addresses the large deformation of the equal-strength beam 20 during large strain measurements, ensuring that the equal-strength relationship always holds, thereby ensuring calibration accuracy and increasing the calibration range. Compared to the prior art, the technical solution of the present invention can address the technical issues in the prior art where the equal-strength relationship does not exist and calibration errors are large when the test beam of the calibration device undergoes large deformation.

[0036] As a specific embodiment of the present invention, the load application unit 40 includes a weight 41 and a counterweight 42. One end of the weight 41 is connected to the free end 22 of the constant strength beam 20, and the other end contains the counterweight 42. With this configuration, the load direction is always perpendicular to the horizontal plane. At the beginning of measurement, the load direction and the constant strength beam 20 are perpendicular to each other. When the load is large and causes the constant strength beam 20 to undergo significant deformation, the constant strength beam 20 and the load are not perpendicular. At this time, the angle between the constant strength beam 20 and the load can be adjusted to 90° by adjusting the angle between the support column 10 and the horizontal plane using the angle adjustment unit 50.

[0037] Further, in order to adjust the angle between the support column 10 and the horizontal plane, please refer to Figure 1In an embodiment, the angle adjustment unit 50 includes a guide rail 51, a slider 52, a connecting rod 53 and a support plate 54. The top of the support plate 54 is connected to the bottom of the support column 10, and the end of the support plate 54 is hinged to the end of the guide rail 51. The slider 52 is set on the guide rail 51 and is connected to the bottom of the support plate 54 through the connecting rod 53. The slider 52 moves along the guide rail 51 to drive the connecting rod 53 to rotate, thereby driving the support plate 54 to rotate in a plane perpendicular to the guide rail 51. Taking the force load applied by the weight 42 as an example, the direction of the force load is always perpendicular to the horizontal plane. At the beginning of the measurement, the direction of the force load is perpendicular to the equal-strength beam 20. The support column 10 is vertically arranged on the upper surface of the support plate 54, and the support plate 54 and the guide slide 51 are parallel to the horizontal plane. As the force load increases, the deformation of the equal-strength beam 20 gradually increases, and the angle between the force load and the equal-strength beam 20 gradually increases. At this time, by pushing the slider 52 toward the hinged end of the support plate 54 and the guide slide 51, the connecting rod 53 can be driven to rotate to push the support plate 54 upward, thereby increasing the angle between the support plate 54 and the guide slide 51. Since the angle between the support plate 54 and the support column 10 remains unchanged, the purpose of reducing the angle between the equal-strength beam 20 and the force load can be achieved. When the two processes reach equilibrium, the equal-strength beam 20 and the force load can be maintained always perpendicular, thereby maintaining the equal-strength relationship.

[0038] To improve the accuracy of angle adjustment, in one embodiment of the present invention, the angle adjustment unit 50 further includes a controller and a driver 5555. The driver 5555 is connected to the slider 52. The angle adjustment unit 50 controls the driver 5555 via the controller to drive the slider 52 to move on the guide rail 51. This configuration improves the digitalization and intelligence of the calibration device and enhances calibration accuracy.

[0039] Please refer to Figure 2In an embodiment, the controller includes a position control module, a speed control module, a position detection and feedback module, and a speed detection and feedback module. The position control module is used to control the movement distance of the slider 52, the speed control module is used to control the movement speed of the slider 52, the position detection and feedback module is used to detect the position information of the slider 52 and feed it back to the position control module, and the speed detection and feedback module is used to detect the speed information of the slider 52 and feed it back to the speed control module. The position detection and feedback module can detect the current position of the slider 52 using a grating. The inner loop is the speed loop, and the outer loop is the position loop. The position command signal is sent via the CNC. The device used for speed detection and feedback in the speed loop is an encoder. The speed control module is an independent unit component, consisting of various components such as a speed regulator, a current regulator, and a drive amplifier. The position loop is composed of the position control module, the speed control module, and the position detection and feedback module. The position command signal and the feedback position signal are comprehensively analyzed through a comparison process to generate a position deviation signal. This signal is then amplified to control the motor to drive the slider 52 to the command position. Position control mainly controls the movement axis of the slider 52, and has strict requirements on the control of the axis's movement speed and position accuracy, thereby ensuring that the equal strength beam 20 is always perpendicular to its force direction.

[0040] Furthermore, as a specific embodiment of the present invention, Figure 1 and Figure 2 As shown, the driver 55 includes a servo motor 551, a coupling, and a ball screw 552 connected in sequence. The servo motor 551 is connected to the controller, and the ball screw 552 is connected to the slider 52. The driver 55 drives the ball screw 552 to rotate through the servo motor 551, thereby driving the slider 52 to move on the guide rail 51. The slider 52 can be fixed to the ball screw 552 by a nut. Through this configuration, the moving speed and distance of the slider 52 can be precisely controlled, thereby ensuring that the constant strength beam 20 is perpendicular to the direction of the force load, that is, the force direction of the constant strength beam 20 is perpendicular to itself.

[0041] Furthermore, to improve the accuracy of force load application, in an embodiment of the present invention, the calibration device further includes a force sensor, which is disposed on the force load application unit 40 and is used to measure the actual force load value applied by the force load application unit 40 to the constant strength beam 20. The actual force load value can be used to determine whether the force applied to the constant strength beam 20 is the expected value, thereby adjusting the force load to achieve the expected value. This configuration improves calibration accuracy.

[0042] Furthermore, to ensure the accuracy of force load application, in one embodiment of the present invention, the force load application unit 40 is configured to include a traction portion, a hollow threaded column, and a base. A threaded hole is provided in the base, and the hollow threaded column moves within the base by cooperating with the threaded hole. The hollow threaded column is sleeved on the traction portion, and one end of the traction portion is connected to the free end 22 of the equal-strength beam 20, and the other end is limited by the hollow threaded column. The force load application unit 40 adjusts the force load applied to the traction portion by moving the hollow threaded column, wherein the traction portion can be made of steel wire. Through this configuration, the magnitude of the force load can be infinitely adjusted, while preventing the traction portion from rotating when the threaded column rotates, thereby continuously calibrating different strains and achieving higher calibration accuracy.

[0043] In addition, the material and size of the equal strength beam 20 are determined according to the actual measurement requirements. When a force load G is applied to the equal strength beam 20, the bending moment M on the cross section at a distance x from the loading point is x for:

[0044] M x =Gx,

[0045] Correspondingly, the maximum stress σ on the section is:

[0046]

[0047] In the above formula, W represents the bending section modulus, assuming the section is rectangular, b x is the width and h is the thickness, then:

[0048]

[0049] Therefore, through the above three formulas, we can get

[0050]

[0051] The so-called equal strength means that the stress in each section is equal under the action of force, that is, the value of σ remains unchanged. Obviously, when the thickness h of the beam remains unchanged, the width of the beam must change with the change of x, so:

[0052]

[0053] From the above formula, we can see that when G, σ and h remain unchanged, The value of b is a fixed value, indicating that x It varies linearly with x.

[0054] Depend on Figure 3 It can be seen that but Therefore, it can be concluded that: Where tgα represents the slope of the uniform strength beam 20. Obviously, once the force load is determined, the allowable stress σ is determined based on the selected beam material. Then, by properly selecting the beam's aspect ratio, the beam thickness h can be calculated. Finally, tgα or α can be calculated based on the requirements of the uniform strength beam 20. After processing, the uniform strength beam 20 can be obtained.

[0055] Taking the maximum strain calibration range of 5000 με as an example, as a specific embodiment of the present invention, quenched manganese steel is selected to manufacture the constant strength beam 20, whose elastic modulus E = 211 GPa, Poisson's ratio μ = 0.288, maximum load G = 70 N, overload coefficient 50%, cross-sectional stress σ is 443 MPa, and the effective size of the test beam is determined to be 380×38×2 according to the aforementioned theoretical formula, that is, the effective length is 380 mm, the thickness is 2 mm, the width of the fixed end 21 is 38 mm, the slope tgα of the effective length section is 0.05, and the shape and size are as follows: Figure 3 and Figure 4 shown.

[0056] Please refer to the method for using the calibration device proposed in this invention. Figure 1 In the embodiment, the optical fiber strain gauge 30 includes an optical fiber strain sensor 31 and a demodulator 32. The optical fiber strain sensor 31 is attached to the equal strength beam 20 and a force load is applied to the equal strength beam 20. Please refer to the calibration process. Figure 5 On the one hand, the demodulator 32 is used to obtain the cavity length signal of the optical fiber strain sensor 31, which is transmitted to the computer. The host computer software collects, records and calculates the parameters of the optical fiber strain sensor 31, analyzes the characteristic indicators and some parameter curves of the optical fiber strain sensor 31, and obtains the strain measurement value; on the other hand, the position signal and speed signal of the slider 52 are obtained through the controller, and the position of the slider 52 is adjusted. The force sensor is used to accurately control the size of the applied force load, and the theoretical strain amount is calculated by the software; finally, the accuracy of the optical fiber strain gauge 30 is determined by comparing and analyzing the measured value and the theoretical value to obtain the calibration result. The software can use LabVIEW.

[0057] In summary, the present invention provides a calibration device for adhesive-type fiber optic strain gauges. This calibration device is achieved by placing an equal-strength beam with an optical fiber strain gauge attached on a support column, configuring a force load application unit at the free end of the equal-strength beam, and configuring an angle adjustment unit to adjust the angle between the support column and the horizontal plane, thereby adjusting the angle between the equal-strength beam and the force load so that the angle between the two is always 90°. In this way, it can effectively cope with large deformations of the equal-strength beam during large strain measurements, ensuring that the equal-strength relationship always holds, thereby ensuring calibration accuracy. Compared with the prior art, the technical solution of the present invention can solve the technical problems of the prior art in which the equal-strength relationship does not exist and the calibration error is large when the test beam of the calibration device undergoes large deformation, thereby improving the calibration range.

[0058] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0059] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A calibration device for an adhesive optical fiber strain gauge, characterized in that: The calibration device includes: a support column; An equal strength beam, the equal strength beam comprising a fixed end and a free end, the equal strength beam being fixed to the supporting column via the fixed end, the equal strength beam being used to carry the optical fiber strain gauge so that the optical fiber strain gauge is fitted on the equal strength beam; a force load applying unit, the force load applying unit being connected to the free end of the equal strength beam and being used to apply a force load to the equal strength beam; An angle adjustment unit is connected to the support column and is used to adjust the angle between the support column and the horizontal plane so that the direction of the force load applied by the force load applying unit is perpendicular to the equal strength beam.

2. The calibration device according to claim 1, characterized in that The angle adjustment unit includes a guide rail, a slider, a connecting rod and a support plate. The top of the support plate is connected to the bottom of the support column, and the end of the support plate is hinged to the end of the guide rail. The slider is set on the guide rail and connected to the bottom of the support plate through the connecting rod. The slider moves along the guide rail to drive the connecting rod to rotate, thereby driving the support plate to rotate in a plane perpendicular to the guide rail.

3. The calibration device according to claim 2, wherein the angle adjustment unit further comprises a controller and a driver, wherein the driver is connected to the slider, and the angle adjustment unit controls the driver through the controller to drive the slider to move on the guide rail.

4. The calibration device according to claim 3, characterized in that The controller includes a position control module, a speed control module, a position detection feedback module and a speed detection feedback module. The position control module is used to control the moving distance of the slider, the speed control module is used to control the moving speed of the slider, the position detection feedback module is used to detect the position information of the slider and feed the position information back to the position control module, and the speed detection feedback module is used to detect the speed information of the slider and feed the speed information back to the speed control module.

5. The calibration device according to claim 4, characterized in that The driver includes a servo motor, a coupling and a ball screw connected in sequence, the servo motor is connected to the controller, the ball screw is connected to the slider, and the driver drives the ball screw to rotate through the servo motor to drive the slider to move on the guide rail.

6. The calibration device according to claim 5, characterized in that The calibration device further includes a force sensor, which is disposed on the force load applying unit and is used to measure an actual force load value applied to the constant strength beam by the force load applying unit.

7. The calibration device according to any one of claims 1 to 6, characterized in that: The force load applying unit includes a weight hanging and a weight. One end of the weight hanging is connected to the free end of the equal strength beam, and the other end contains the weight.

8. The calibration device according to any one of claims 1 to 6, characterized in that: The force load applying unit includes a traction part, a hollow threaded column and a base. A threaded hole is provided in the base. The hollow threaded column moves in the base by cooperating with the threaded hole. The hollow threaded column is sleeved on the traction part and one end of the traction part is connected to the free end of the equal-strength beam, and the other end is limited on the hollow threaded column. The force load applying unit adjusts the force load applied to the traction part by moving the hollow threaded column.

9. The calibration device according to claim 8, characterized in that The material of the equal strength beam is manganese steel.

10. The calibration device according to claim 9, characterized in that The effective length of the equal strength beam is 380 mm, the thickness is 2 mm, the width of the fixed end is 38 mm, and the slope of the effective length section is 0.05.

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