CN114544782A - Sensor calibration device based on embedded PVDF piezoelectric film and calibration method thereof - Google Patents
Sensor calibration device based on embedded PVDF piezoelectric film and calibration method thereof Download PDFInfo
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- CN114544782A CN114544782A CN202210185864.XA CN202210185864A CN114544782A CN 114544782 A CN114544782 A CN 114544782A CN 202210185864 A CN202210185864 A CN 202210185864A CN 114544782 A CN114544782 A CN 114544782A
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000002033 PVDF binder Substances 0.000 title claims abstract description 19
- 229920002981 polyvinylidene fluoride Polymers 0.000 title claims abstract description 19
- 238000012360 testing method Methods 0.000 claims abstract description 45
- 229920003023 plastic Polymers 0.000 claims abstract description 20
- 239000004033 plastic Substances 0.000 claims abstract description 20
- 239000000463 material Substances 0.000 claims description 13
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims description 5
- 239000000565 sealant Substances 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims description 2
- 230000003287 optical effect Effects 0.000 claims description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 2
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 2
- 239000010959 steel Substances 0.000 claims description 2
- 239000008188 pellet Substances 0.000 abstract description 8
- 230000007547 defect Effects 0.000 abstract description 3
- 239000011435 rock Substances 0.000 description 5
- 230000003116 impacting effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000011324 bead Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000005316 response function Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000004613 tight binding model Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0232—Glass, ceramics, concrete or stone
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- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
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- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
The invention discloses a sensor calibration device based on an embedded PVDF piezoelectric film and a calibration method thereof, wherein the sensor calibration device comprises a triangular prism-shaped test platform, wherein the bottom surface of the triangular prism is an isosceles right triangle; the testing platform is provided with through holes which penetrate through two bottom surfaces of the testing platform, and the sensor is coupled into the testing platform through the through holes; the sensor is connected with the amplifier device and used for capturing signals; the side surface where the bevel edge of the isosceles right triangle of the test platform is located is a top surface, the top surface is horizontally arranged, and a plastic straight pipe is vertically fixed on the top surface; the plastic straight pipe is internally provided with a channel for the pellets to vertically fall into, and the plastic straight pipe is provided with a scale for measuring the impact speed of the pellets. The method takes the small balls as calibration sources, is simple, has easily determined parameters, and can make up for the defects of the precision and the application range of the acoustic emission system.
Description
Technical Field
The invention relates to the technical field of geophysics, in particular to a sensor calibration device based on an embedded PVDF piezoelectric film and a calibration method thereof.
Background
The acoustic emission refers to the phenomenon that strain energy is released rapidly at local parts after the material is stressed so as to generate transient elastic waves, and when the material is detected by adopting an acoustic emission method, the related information of an acoustic emission source in the detected material can be obtained. In the rock, acoustic emission is a companion phenomenon of the process of initiation, expansion and fracture of micro-cracks in the rock, the internal instability fracture evolution process of the rock can be obtained by adopting an acoustic emission method, the internal fracture position can be positioned, and after the information of an internal acoustic emission source is analyzed and processed, a plurality of information about the internal damage process of the rock can be obtained. Therefore, the acoustic emission technology is widely applied to research on rock fracture and fault instability problems in geotechnical engineering, tunnel engineering and seismic engineering. Most acoustic emission detection systems have high sensitivity piezoelectric sensors and high gain recording devices, however, the sensors and recording devices are usually not calibrated, which not only makes the phenomenon observed experimentally difficult to explain, but also causes the reliability and practicability of the acoustic emission method to be limited.
The existing method for calibrating acoustic emission systems is to calibrate by calculating the influence of the sensor response, filters, amplifiers and elastic wave propagation in dynamic deformations in the system. During this calibration, the response of each component in the system will have an effect on the whole. However, the response of the elastic wave propagation can be described by the corresponding green function, and the response of the sensor and recording device can be described by the instrument response function. Therefore, in order to solve this problem, a method of calibrating the system (sensor, amplifier, data recorder, etc.) as a whole has been proposed.
Disclosure of Invention
Based on the importance and practicability of acoustic emission system calibration, the invention provides a sensor calibration device based on an embedded PVDF piezoelectric film and a calibration method thereof, wherein the sensor calibration device is used as a small ball of an ideal calibration source, related physical quantities of the sensor calibration device can be directly obtained through measurement, the system can be simply calibrated by utilizing a known formula, and the frequency amplitude difference of waves emitted by small ball impact is large, so that the waves are easy to distinguish. The calibrated acoustic emission system can obtain the stick-slip phenomenon and the displacement of the fault stick-slip in the dynamic triggering earthquake, and can obtain the relevant parameters of the earthquake source, such as earthquake moment, angular frequency, stress drop and the like, thereby providing a reliable test method for engineering measurement of the displacement of the fault plane and determination of the relevant parameters of the earthquake source, and making up the defects of the acoustic emission system in precision and application range. The device has simple structure, convenient operation, direct measurement of relevant parameters and repeatability.
The invention is realized by the following technical scheme:
the sensor calibration device based on the embedded PVDF piezoelectric film comprises a triangular prism-shaped test platform, wherein the bottom surface of the triangular prism is an isosceles right triangle; the testing platform is provided with through holes which penetrate through two bottom surfaces of the testing platform, and the sensor is coupled into the testing platform through the through holes;
the sensor is connected with the amplifier device and used for capturing signals;
the side surface where the bevel edge of the isosceles right triangle of the test platform is located is a top surface, the top surface is horizontally arranged, and a plastic straight pipe is vertically fixed on the top surface; the plastic straight pipe is internally provided with a channel for the pellets to vertically fall into, and the plastic straight pipe is provided with a scale for measuring the impact speed of the pellets.
And chamfering treatment is carried out on each end angle of the test platform, and the chamfering angle is 45 degrees.
The test platform is made of materials with good wave propagation effects such as aluminum, steel, glass or polymethyl methacrylate;
the through holes are arranged on the same horizontal line.
The sensor is a PVDF piezoelectric film and is coupled with the through hole of the test platform through a sealant.
Further comprising: the electric measurement system comprises a dynamic signal acquisition and analysis device and a signal amplifier device, wherein the sensor is connected with the signal amplifier device and captures signals; the optical acquisition system refers to a high-speed camera.
The method comprises the following steps:
adjusting an experimental device and parameters thereof, recording the signal change conditions before and after the adjustment, and carrying out experimental research according to the recorded data; wherein the adjusted objects include one or more of:
a test platform material; the impact height of the pellets; the size of the pellet; a pellet material; the location of the through-hole.
The sensor calibration method based on the embedded PVDF piezoelectric film by adopting the sensor calibration device based on the embedded PVDF piezoelectric film comprises the following processes:
and placing the small balls at the upper end of the plastic straight pipe to enable the small balls to freely fall, and impacting the test platform through the plastic straight pipe.
And obtaining the relation between the displacement and the time when the small ball impacts the test platform through the high-speed camera, thereby calculating the speed when the small ball impacts. Recording the ratio of a corresponding voltage signal S (omega) and a theoretical signal U (omega) generated by small ball impact according to a dynamic acquisition system to obtain the instrument response I (omega) of the sensor;
and (3) changing the impact parameters of the small balls, and the materials and the sizes of the test platform, and researching the influence of the small ball impact on the acoustic emission system under different conditions.
The system takes the small balls as calibration sources, not only is the method simple and the parameters easy to determine, but also can make up for the defects of the precision and the application range of the acoustic emission system.
Drawings
FIG. 1 is a schematic view of the structure of the present invention.
Detailed Description
The present invention is described in detail below with reference to the following embodiments and the attached drawings, but it should be understood that the embodiments and the attached drawings are only used for the illustrative description of the present invention and do not limit the protection scope of the present invention in any way. All reasonable variations and combinations that fall within the spirit of the invention are intended to be within the scope of the invention.
The sensor calibration device based on the embedded PVDF piezoelectric film comprises a triangular prism-shaped test platform 11, wherein the bottom surface of the triangular prism is an isosceles right triangle; a through hole 12 is arranged on the test platform 11, the through hole 12 penetrates through two bottom surfaces of the test platform 11, and the sensor is coupled into the test platform 11 through the through hole 12;
the sensor is connected with the amplifier device and used for capturing signals;
the side face where the bevel edge of the isosceles right triangle of the test platform 11 is located is a top face, the top face is horizontally arranged, and a plastic straight pipe 22 is vertically fixed on the top face; the plastic straight pipe 22 is internally provided with a channel for the small ball 21 to vertically fall, and the plastic straight pipe 22 is provided with a scale 23 for measuring the impact speed of the small ball 21.
One end of the sensor is coupled into the test platform 11 through the sealant, and the output end of the sensor is connected to the signal amplifier device, and then the output end of the amplifier device is connected to the dynamic signal acquisition and analysis device.
The center of the through hole 12 is e mm away from the top surface of the test platform 11.
The distance fmm between the adjacent through holes 12; an acoustic emission sensor is pasted on one side of the test platform 11 and used for triggering the high-speed camera.
The small ball 21 is put on the upper end of the plastic straight pipe 22, so that the small ball freely falls, and impacts the test platform 11 through the plastic straight pipe 22.
The distance between the plastic straight pipe 22 and the test platform 11 is adjusted, so that the small ball 21 just touches the top surface of the test platform 11 when falling. At a certain height, the small ball 21 passes through one end of the plastic straight pipe 22 and impacts the test platform 11; the impact process of the small ball 21 is recorded by a high-speed camera, and the small ball 21 is obtained by the ruler 23The displacement in the striking time period so as to calculate the speed v when the small ball 21 impacts the test platform 110. The impact force f (t) should be determined by equation 1.
Wherein the content of the first and second substances,
δi＝(1-μi 2)/(i＝1,2； (4)
in the formula tcRepresents the contact time of the small ball 21 and the test platform 11; f. ofmaxIndicating the maximum impact force exerted by the ball 21 during this time; e and μ represent the Young's modulus and Poisson's ratio of the material, respectively; when i is 1, the relevant material parameter of the small ball 21 is shown, and when i is 2, the relevant material parameter of the test platform 11 is shown; r1And v1Respectively, the radius and impact velocity of the small ball 21; ρ is a unit of a gradient1Indicating the density of the beads 21.
The relationship between the displacement of the small ball 21 when impacting the test platform 11 and the time is obtained through a high-speed camera, so that the speed of the small ball 21 when impacting is calculated. And recording the ratio of the corresponding voltage signal S (omega) and a theoretical signal U (omega) generated by the small ball 21 impact according to a dynamic acquisition system to obtain the instrument response I (omega) of the sensor.
Impact parameters of the small ball 21 and materials, sizes and the like of the test platform 11 are changed, and the influence of the impact of the small ball 21 on the acoustic emission system under different conditions is researched.
More specifically, the impact parameters of the small ball 21 include: pellet 21 material, size, impact height, etc.
The parameters e and f can be freely selected according to actual needs.
Claims (7)
1. The sensor calibration device based on the embedded PVDF piezoelectric film is characterized by comprising a triangular prism-shaped test platform (11), wherein the bottom surface of the triangular prism is an isosceles right triangle; arranging a through hole (12) on the test platform (11), wherein the through hole (12) penetrates through two bottom surfaces of the test platform (11), and the sensor is coupled into the test platform (11) through the through hole (12);
the side surface where the bevel edge of the isosceles right triangle of the test platform (11) is located is a top surface, the top surface is horizontally arranged, and a plastic straight pipe (22) is vertically fixed on the top surface; the device is characterized in that a channel is arranged in the plastic straight pipe (22) and used for enabling the small ball (21) to vertically fall into the channel, and a scale (23) is arranged on the plastic straight pipe (22) and used for measuring the impact speed of the small ball (21).
2. The embedded PVDF piezoelectric film-based sensor calibration device as claimed in claim 1, wherein each end corner of the test platform (11) is chamfered, and the chamfer angle is 45 °.
3. The embedded PVDF piezoelectric film-based sensor calibration device as claimed in claim 1, wherein said test platform (11) is made of aluminum, steel, glass or polymethyl methacrylate.
4. The sensor calibration device based on the embedded PVDF piezoelectric film as recited in claim 1, wherein the plurality of through holes (12) are arranged on the same horizontal line.
5. The embedded PVDF piezoelectric film-based sensor calibration device as recited in claim 1, wherein the sensor is PVDF piezoelectric film, and the sensor is coupled with the through hole (12) of the test platform (11) through a sealant.
6. The embedded PVDF piezoelectric film-based sensor calibration device as claimed in claim 1, further comprising: the electric measurement system comprises a dynamic signal acquisition and analysis device and a signal amplifier device, wherein the sensor is connected with the signal amplifier device and captures signals; the optical acquisition system refers to a high-speed camera.
7. The calibration method of the sensor based on the embedded PVDF piezoelectric film is characterized in that the calibration device of the sensor based on the embedded PVDF piezoelectric film, which is used by any one of claims 1 to 6, comprises the following steps:
the small ball (21) is put into the upper end of the plastic straight pipe (22) to enable the small ball to freely fall, and the test platform (11) is impacted through the plastic straight pipe (22).
The relationship between the displacement of the ball (21) when it impacts the test platform (11) and the time is obtained by a high-speed camera, and the speed of the ball (21) when it impacts is calculated. According to the ratio of a corresponding voltage signal S (omega) and a theoretical signal U (omega) generated by the impact of the small ball (21) recorded by the dynamic acquisition system, obtaining the instrument response I (omega) of the sensor;
impact parameters of the small ball (21) and materials and sizes of the test platform (11) are changed, and the influence of the impact of the small ball (21) on the acoustic emission system under different conditions is researched.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210185864.XA CN114544782A (en) | 2022-02-28 | 2022-02-28 | Sensor calibration device based on embedded PVDF piezoelectric film and calibration method thereof |
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| CN202210185864.XA CN114544782A (en) | 2022-02-28 | 2022-02-28 | Sensor calibration device based on embedded PVDF piezoelectric film and calibration method thereof |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104198146A (en) * | 2014-08-14 | 2014-12-10 | 东北农业大学 | Agricultural material collision recovery coefficient test platform |
| CN210982082U (en) * | 2019-10-16 | 2020-07-10 | 江西省科学院应用物理研究所 | Detection apparatus for coating crack initiation toughness |
| CN212780867U (en) * | 2020-07-24 | 2021-03-23 | 北京神州泰科科技有限公司 | Free drop test terminal speed measuring device |
| CN113376684A (en) * | 2021-06-11 | 2021-09-10 | 天津大学 | Experimental method for researching water injection induced earthquake fault fracture process |
| CN113984907A (en) * | 2021-11-04 | 2022-01-28 | 济南大学 | Method for calibrating dynamic and static characteristics of acoustic emission sensor |
-
2022
- 2022-02-28 CN CN202210185864.XA patent/CN114544782A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104198146A (en) * | 2014-08-14 | 2014-12-10 | 东北农业大学 | Agricultural material collision recovery coefficient test platform |
| CN210982082U (en) * | 2019-10-16 | 2020-07-10 | 江西省科学院应用物理研究所 | Detection apparatus for coating crack initiation toughness |
| CN212780867U (en) * | 2020-07-24 | 2021-03-23 | 北京神州泰科科技有限公司 | Free drop test terminal speed measuring device |
| CN113376684A (en) * | 2021-06-11 | 2021-09-10 | 天津大学 | Experimental method for researching water injection induced earthquake fault fracture process |
| CN113984907A (en) * | 2021-11-04 | 2022-01-28 | 济南大学 | Method for calibrating dynamic and static characteristics of acoustic emission sensor |
Non-Patent Citations (4)
| Title |
|---|
| BILL S. WU等: "Broadband Calibration of Acoustic Emission and Ultrasonic Sensors from Generalized Ray Theory and Finite Element Models", JOURNAL OF NONDESTRUCTIVE EVALUATION, vol. 37, no. 8, pages 1 - 16, XP036441518, DOI: 10.1007/s10921-018-0462-8 * |
| M G DROUBI等: "Acoustic emission monitoring of abrasive particle impacts on carbon steel", PROC. IMECHE VOL. 226 PART E: J. PROCESS MECHANICAL ENGINEERING, pages 187 - 204 * |
| 徐冉等: "实验室地震中植入式超声传感器标定", 《中国地球科学联合学术年会 2021》, pages 12 * |
| 郭玲莉: "断层失稳滑动瞬态过程的实验观测与分析", 中国博士学位论文全文数据库基础科学辑, no. 5, pages 51 - 54 * |
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