CN107091878B - Young modulus measuring instrument based on transient excitation - Google Patents
Young modulus measuring instrument based on transient excitation Download PDFInfo
- Publication number
- CN107091878B CN107091878B CN201710285836.4A CN201710285836A CN107091878B CN 107091878 B CN107091878 B CN 107091878B CN 201710285836 A CN201710285836 A CN 201710285836A CN 107091878 B CN107091878 B CN 107091878B
- Authority
- CN
- China
- Prior art keywords
- speed sensor
- vibration
- solid sample
- sample column
- sample
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Classifications
-
- 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
- G01N29/04—Analysing solids
- G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
- G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
- G09B23/08—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for statics or dynamics
- G09B23/10—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for statics or dynamics of solid bodies
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Mathematical Optimization (AREA)
- Mathematical Physics (AREA)
- Pure & Applied Mathematics (AREA)
- Business, Economics & Management (AREA)
- Computational Mathematics (AREA)
- Educational Administration (AREA)
- Educational Technology (AREA)
- Algebra (AREA)
- Acoustics & Sound (AREA)
- Mathematical Analysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a transient excitation-based Young modulus measuring instrument which comprises a sample fixing and stress wave excitation device and a data acquisition and processing system, and comprises a tripod, a supporting rod, an aluminum fixing ring, a solid sample column, a resonance extension frame, a speed sensor, a nylon round-head hammer, a vibration signal transmission line and a data acquisition and processing system case. The principle is that a small hammer is used for knocking a sample column to generate transient broadband vibration signals, multi-mode standing waves are formed in a sample, the vibration signals of the sample are measured through speed sensors arranged at different parts of the sample, and the vibration frequency, the solid medium acoustic velocity and the Young modulus of the sample can be obtained through frequency spectrum analysis and vibration mode identification; compared with the existing steady-state ultrasonic method and time domain measurement method, the invention can simplify the excitation device, improve the measurement precision of the sound velocity and the Young modulus of the medium, and has wide application prospect in the fields of engineering geology, mechanical engineering, material science and the like.
Description
Technical Field
The invention relates to an instrument for measuring the Young modulus of a solid, in particular to a transient excitation-based Young modulus measuring instrument.
Background
Various methods and means are available for measuring the Young's modulus of a solid, and commonly used measuring methods in practical engineering include a stretching method, a dynamic suspension method, an ultrasonic sound velocity method and the like. The stretching method is a static method, which is to apply a force to strain a sample material to be measured, and measure the strain through an electrical or optical method, so as to obtain the young modulus of the material; the method is inconvenient to measure and low in measurement precision. The dynamic suspension method and the ultrasonic sound velocity method both adopt dynamic methods, and can obtain the Young modulus of a sample material by exciting the sample material to generate vibration or ultrasonic waves and measuring the vibration frequency of the sample or the transmission time of the ultrasonic waves in the sample. In the practical measurement of the Young modulus of a solid material, an ultrasonic speed method is mainly adopted, and because a dynamic method needs to generate a steady-state excitation source for the whole or local vibration of a sample, the device is complex, the cost is high, the frequency band is narrow, and the measurement precision is limited. Compared with ultrasonic steady-state excitation, the transient stress excitation does not need special steady-state excitation equipment, and the broadband excitation can be realized only by mechanical knocking, so that the structure of the instrument is simplified, and the production and use cost of the instrument is reduced; and secondly, the measurement precision of the Young modulus can be improved by synchronously or asynchronously measuring the vibration of the multi-point standing wave in the sample and calculating according to different modes of the standing wave in the medium by using a frequency spectrum analysis method.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a young modulus measuring apparatus based on transient excitation, which not only can provide identification of vibration modes and measure propagation velocity of acoustic waves in a solid, but also has a simple structure and good stability, and can automatically analyze and calculate a vibration fundamental frequency, an acoustic velocity and a young modulus of a solid medium of a sample.
The embodiment of the invention provides a transient excitation-based Young modulus measuring instrument, which comprises a sample fixing and stress wave excitation device and a data acquisition and processing system; the sample fixing and stress wave excitation device comprises a sample fixing device, a solid sample column, a small hammer, a first speed sensor, a second speed sensor, a third speed sensor and a fourth speed sensor; the solid sample column is arranged on the sample fixing device, the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor are respectively arranged at the top of the solid sample column, one quarter of the top of the solid sample column, one half of the top of the solid sample column and the bottom of the solid sample column, and the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor are respectively connected with the data acquisition and processing system through vibration signal transmission lines; the data acquisition and processing system comprises a filter circuit, a precise differential amplifier, a signal acquisition switch circuit, ADC (analog to digital converter), a microcontroller and related detection, control and signal processing software; the filter circuit and the precise differential amplifier are used for reducing noise and improving the stability of a measurement signal; the microcontroller is used for collecting a sample vibration signal subjected to analog-to-digital conversion by the ADC and sending the sample vibration signal to the upper computer for data processing and analysis and calculation; the small hammer is used for knocking the upper end face or the lower end face of the sample column, triggering a transient broadband vibration signal, generating a stress wave on the solid sample column, forming standing waves in various modes, measuring speed signals of various standing waves generated by vibration at various positions of the solid sample column through the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor, and transmitting the speed signals to the data acquisition and processing system through the vibration signal transmission line.
Further, the sample holding device comprises a tripod, a support bar and at least two holding rings; the tripod is placed on a horizontal table top or the ground, the supporting rod is vertically screwed in a central hole of the tripod through threads, and the solid sample column is fixed on the supporting rod of the tripod along the vertical direction by the fixing ring.
Furthermore, one end of the fixing ring is fixed on the supporting rod, and the other end of the fixing ring is flexibly connected with the solid sample column through the annular metal sheet, so that the solid sample column can be stably in a vertical suspended state, the solid sample column is guaranteed to be in a free vibration state, and excitation of multiple vibration modes is facilitated.
Furthermore, a resonance extension frame is respectively fixed at the top of the solid sample column, one fourth of the top of the solid sample column, one half of the top of the solid sample column and the bottom of the solid sample column, and a first speed sensor, a second speed sensor, a third speed sensor and a fourth speed sensor are respectively installed on the extension plane of the resonance extension frame; the vibration in the plane of the resonant spreader can be considered to coincide with the vertical vibration of the solid sample column at that point, and a velocity sensor fixed to the plane of the resonant spreader can measure the vertical vibration velocity of the solid sample column at that point.
Furthermore, the data acquisition and processing system is assembled in an independent box body, and a front panel of the box body is provided with four vibration signal input ports and a USB output port; the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor are respectively connected to a vibration signal input port of the data acquisition and processing system through vibration signal transmission lines; and the data acquisition and processing system is connected with an upper computer through a USB output interface.
Further, the small hammer is a nylon round-head small hammer.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
(1) compared with ultrasonic steady-state excitation, transient stress excitation does not need steady-state excitation equipment, broadband excitation is realized, the display contents of vibration and standing wave phenomena are richer, the structure of the instrument is simplified, and the production and use costs of the instrument are reduced;
(2) the method of spectral analysis and vibration mode identification can be used for measuring the frequencies of a plurality of relevant modes, and the measurement precision of the vibration frequency of the sample is improved through average processing. If the density r and the length l of the sample medium are known, the fundamental frequency f of the sample vibration is obtained by the method described above1Then u is 2lf1And E ═ ru2The propagation speed of the stress wave in the sample medium and the Young modulus of the solid medium are respectively calculated. Generally, the measurement precision in the frequency domain is higher than that in the time domain, so that the method can obviously improve the measurement precision of the wave velocity and the Young modulus;
(3) the device can be used as a teaching instrument for demonstrating transient excitation, stress wave propagation in a solid medium and generation and measurement of various vibration modes; the demonstration effect is obvious, and the operation is simple and easy.
Drawings
FIG. 1 is a schematic structural view of a Young's modulus measuring instrument according to the present invention.
FIG. 2 is a functional block diagram of a data acquisition and processing system.
In the figure: 1. a tripod; 2. a support bar; 3. a fixing ring; 4. a column of solid samples; 5. a resonance extension frame; 6. a small hammer; 7. a first speed sensor; 8. a second speed sensor; 9. a third speed sensor; 10. a fourth speed sensor; 11. a vibration signal transmission line; 12. a data acquisition and processing system; 121. a filter circuit; 122. a precision differential amplifier; 123. a signal acquisition switching circuit; 124. ADC analog-to-digital conversion; 125. a microcontroller; 13. and (4) an upper computer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be further described with reference to the accompanying drawings.
The embodiment of the invention provides a transient excitation-based Young modulus measuring instrument, which comprises a sample fixing and stress wave excitation device and a data acquisition and processing system 12.
Referring to fig. 1, the sample fixing and stress wave exciting apparatus includes a tripod 1, a support rod 2, a fixing ring 3, a solid sample column 4, a resonant extension frame 5, a hammer 6, a first speed sensor 7, a second speed sensor 8, a third speed sensor 9, a fourth speed sensor 10, and a vibration signal transmission line 11. The tripod 1 is placed on a horizontal table top or the ground, the supporting rod 2 is vertically screwed in a central hole of the tripod 1 through threads, one end of an aluminum fixing ring 3 is fixed on the supporting rod 2, and the other end of the aluminum fixing ring is flexibly connected with the solid sample column 4 through an annular metal sheet, so that the solid sample column 4 can be stably in a vertical suspended state, the solid sample column 4 can be ensured to freely vibrate, and excitation of various vibration modes is facilitated. Resonance extending frames 5 are respectively fixed at the top, the bottom, the quarter and the half of the top of the solid sample column 4, and a first speed sensor 7, a second speed sensor 8, a third speed sensor 9 and a fourth speed sensor 10 are respectively arranged on the extending planes of the resonance extending frames 5 from top to bottom and are used for obtaining vibration speed signals of the sample column at the positions. The plane vibration of the resonance extension stage 5 can be considered to coincide with the vertical vibration of the solid sample column 4 at that point, and therefore, the first velocity sensor 7, the second velocity sensor 8, the third velocity sensor 9, and the fourth velocity sensor 10 fixed on the extension plane of the resonance extension stage 5 can measure the vertical vibration velocity of the solid sample column 4 at that point. The small hammer 6 is a nylon round-head small hammer and is used for knocking the upper end face or the lower end face of the sample column 4 to trigger a transient broadband vibration signal, generating a stress wave on the solid sample column 4 and forming standing waves in various modes, measuring vibration speed signals of various standing waves generated at various positions of the solid sample column 4 through the first speed sensor 7, the second speed sensor 8, the third speed sensor 9 and the fourth speed sensor 10, and transmitting the vibration speed signals to the data acquisition and processing system 12 through the vibration signal transmission line 11.
Referring to fig. 2, a schematic block diagram of a data acquisition and processing system 12 of the present invention is shown, wherein the data acquisition and processing system includes a filter circuit 121, a precision differential amplifier 122, a signal acquisition switch circuit 123, an ADC analog-to-digital converter 124, a microcontroller 125 and related detection, control and signal processing software; the filter circuit 121 and the precision differential amplifier 122 are used for reducing noise and improving the stability of the measurement signal; the microcontroller 125 is used for collecting the sample vibration signal subjected to the ADC analog-to-digital conversion 124, and sending the sample vibration signal to the upper computer 13 for data processing and analysis and calculation; the microcontroller 125 controls the signal acquisition switch circuit 123 to turn on and off. The data acquisition and processing system 12 has a plurality of channels, and the microcontroller 125 can perform high-speed real-time acquisition on signals of a plurality of speed sensors (a first speed sensor 7, a second speed sensor 8, a third speed sensor 9 and a fourth speed sensor 10), wherein the sampling rate is 1 MHz; the multi-channel collection can simultaneously show various vibration modes at multiple positions of the solid sample column, and the high-speed collection can ensure the precision and the integrity of signals. The microcontroller 125 is connected with the upper computer 13 through a USB interface, the setting of initial parameters, and the processing, analysis and display of data of each speed sensor (the first speed sensor 7, the second speed sensor 8, the third speed sensor 9 and the fourth speed sensor 10) can be completed on the upper computer 13, and the intellectualization of the measurement of the Young modulus of the solid is realized. The upper computer 13 in this application uses a computer.
The data acquisition and processing system 12 is of modular design and is additionally packaged, and a signal transmission interface of the system is connected with each speed sensor through a vibration signal transmission line 11. The box body of the system is of a metal sealing structure, is rain-proof and moisture-proof, shields interference, and can flexibly select an installation place according to a measurement site environment.
The working process of the transient excitation-based Young modulus measuring instrument comprises the following steps:
the solid sample column 4 is fixed on the support rod 2 of the tripod 1 along the vertical direction by the fixing ring 3; lightly knocking the upper end surface of the solid sample column 4 by a nylon round-head hammer 6 to generate transient stress waves (acoustic waves) in the solid sample column 4 and reflecting back and forth between the two end surfaces of the solid sample column 4 to form standing waves; is arranged at the top of the solid sample column 4, is one fourth column length away from the top end and is one half column lengthThe first speed sensor 7, the second speed sensor 8, the third speed sensor 9 and the fourth speed sensor 10 on the extension plane of the bottom resonance extension frame 5 collect vibration speed signals of the solid sample column 4 at the positions, the collected vibration speed signals are respectively transmitted to the data collecting and processing system 12 through the vibration signal transmission line 11, in the data acquisition and processing system 12, the vibration velocity signals at the four locations are first processed by the filter circuit 121, then gain-amplified by a precise differential amplifier 122, transmitted to a signal acquisition switching circuit 123, the analog signal is converted into a digital signal by the ADC analog-to-digital conversion 124 and output to the microcontroller 125, the USB interface is transmitted to the upper computer 13 (computer), and the computer performs mode frequency measurement and data processing by using a method of spectrum analysis and vibration mode identification to obtain the fundamental frequency f of the sample vibration.1The density r and the length l of the sample medium are known, and are then determined according to the formula u-2 lf1Calculating the propagation speed of the stress wave in the sample medium according to the formula E ═ ru2The young's modulus of the solid sample column 4 is calculated.
The instrument can measure the stress wave velocity of the solid medium, can also dynamically measure the mechanical property of the medium material, and has wide application prospect in the fields of engineering geology, civil construction, mechanical engineering, material science and the like.
In this document, the terms front, back, upper and lower are used to define the components in the drawings and the positions of the components relative to each other, and are used for clarity and convenience of the technical solution. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.
The features of the embodiments and embodiments described herein above may be combined with each other without conflict.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. Base of a fuel cellThe transient excited Young's modulus measuring instrument includes sample fixing and stress wave exciting device and data acquiring and processing system; the method is characterized in that: the sample fixing and stress wave excitation device comprises a sample fixing device, a solid sample column, a small hammer, a first speed sensor, a second speed sensor, a third speed sensor and a fourth speed sensor; the solid sample column is arranged on the sample fixing device, the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor are respectively arranged at the top of the solid sample column, one quarter of the top of the solid sample column, one half of the top of the solid sample column and the bottom of the solid sample column, and the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor are respectively connected with the data acquisition and processing system through vibration signal transmission lines; the data acquisition and processing system comprises a filter circuit, a precise differential amplifier, a signal acquisition switch circuit, ADC (analog to digital converter), a microcontroller and related detection, control and signal processing software; the filter circuit and the precise differential amplifier are used for reducing noise and improving the stability of a measurement signal; the microcontroller is used for collecting a sample vibration signal subjected to analog-to-digital conversion by the ADC and sending the sample vibration signal to the upper computer for data processing and analysis and calculation; the small hammer is used for knocking the upper end face or the lower end face of the sample column, triggering a transient broadband vibration signal, generating a stress wave on the solid sample column, forming standing waves in various modes, measuring speed signals of various standing waves generated by vibration at various positions of the solid sample column through the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor, and transmitting the speed signals to the data acquisition and processing system through the vibration signal transmission line; the method of frequency spectrum analysis and vibration mode identification can be used for measuring the frequencies of a plurality of relevant modes, and the measurement precision of the vibration frequency of the sample is improved through average processing; if the density r and the length l of the sample medium are known, the fundamental frequency f of the sample vibration is obtained by the method described above1Then u is 2lf1And E ═ ru2The propagation speed of the stress wave in the sample medium and the Young modulus of the solid medium are respectively calculated.
2. The young's modulus measuring instrument based on transient excitation according to claim 1, wherein: the sample fixing device comprises a tripod, a support rod and at least two fixing rings; the tripod is placed on a horizontal table top or the ground, the supporting rod is vertically screwed in a central hole of the tripod through threads, and the solid sample column is fixed on the supporting rod of the tripod along the vertical direction by the fixing ring.
3. The young's modulus measuring instrument based on transient excitation as claimed in claim 2, wherein: one end of the fixing ring is fixed on the supporting rod, and the other end of the fixing ring is flexibly connected with the solid sample column through the annular metal sheet, so that the solid sample column can be stably in a vertical suspended state, the solid sample column is guaranteed to be in a free vibration state, and excitation of various vibration modes is facilitated.
4. The young's modulus measuring instrument based on transient excitation according to claim 1, wherein: resonance extension frames are respectively fixed at the top of the solid sample column, one fourth of the top of the solid sample column, one half of the top of the solid sample column and the bottom of the solid sample column, and a first speed sensor, a second speed sensor, a third speed sensor and a fourth speed sensor are respectively arranged on extension planes of the resonance extension frames from top to bottom; the vibration in the plane of the resonant spreader can be considered to coincide with the vertical vibration of the solid sample column at that point, and a velocity sensor fixed to the plane of the resonant spreader can measure the vertical vibration velocity of the solid sample column at that point.
5. The young's modulus measuring instrument based on transient excitation according to claim 1, wherein: the data acquisition and processing system is integrated in an independent box body, and the front panel of the box body is provided with four vibration signal input ports and a USB output port; the first speed sensor, the second speed sensor, the third speed sensor and the fourth speed sensor are respectively connected to a vibration signal input port of the data acquisition and processing system through vibration signal transmission lines; and the data acquisition and processing system is connected with an upper computer through a USB output interface.
6. The young's modulus measuring instrument based on transient excitation according to claim 1, wherein: the small hammer is a nylon round-head small hammer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710285836.4A CN107091878B (en) | 2017-04-27 | 2017-04-27 | Young modulus measuring instrument based on transient excitation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710285836.4A CN107091878B (en) | 2017-04-27 | 2017-04-27 | Young modulus measuring instrument based on transient excitation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107091878A CN107091878A (en) | 2017-08-25 |
| CN107091878B true CN107091878B (en) | 2020-08-07 |
Family
ID=59638731
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710285836.4A Expired - Fee Related CN107091878B (en) | 2017-04-27 | 2017-04-27 | Young modulus measuring instrument based on transient excitation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107091878B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114428025B (en) * | 2022-01-04 | 2023-09-26 | 苏州热工研究院有限公司 | Portable internal consumption measuring instrument and internal consumption measuring method |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4845989A (en) * | 1987-09-04 | 1989-07-11 | Titlow Joseph D | Method and apparatus for determining elastic constants in tubes |
| CN202814930U (en) * | 2012-08-09 | 2013-03-20 | 浙江托普仪器有限公司 | Standing tree trunk Young modulus measurement device |
| CN104849147A (en) * | 2015-05-26 | 2015-08-19 | 山东交通学院 | Modal natural frequency-based metal material Young modulus measurement device and method |
| CN205426685U (en) * | 2016-03-22 | 2016-08-03 | 宿迁学院 | Young modulus measuring instrument of convenient experiment teaching usefulness |
| CN106053606A (en) * | 2016-05-07 | 2016-10-26 | 田凯 | Experiment device and method adopting resonance principle to measure Young modulus of metal wire |
-
2017
- 2017-04-27 CN CN201710285836.4A patent/CN107091878B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN107091878A (en) | 2017-08-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3617036B2 (en) | Ground exploration device and analysis program used therefor | |
| CN103698404B (en) | Damping material fissipation factor measuring method based on impulse response method and measurement apparatus | |
| US20150153311A1 (en) | System for measuring propagation velocity of sound wave and method of measuring propagation velocity of sound wave | |
| CN201653999U (en) | Intelligent ultrasonic transverse wave and longitudinal wave comprehensive tester | |
| CN1873406B (en) | Comprehensive test instrument for performance of acoustic material | |
| CN107091878B (en) | Young modulus measuring instrument based on transient excitation | |
| CN105277967A (en) | Water tank physical model ultrasonic automatic detection system and method | |
| Zaalishvili | Measurement and recording equipment for seismic microzoning | |
| CN111412974A (en) | System and method for calibrating co-vibration vector sensor | |
| CN204924435U (en) | Sound duct is measured in sensitivity of hydrophone low frequency | |
| CN102681009B (en) | Multi-channel transient Rayleigh wave test system and method | |
| CN203466956U (en) | Amplitude and phase variable double-resonance sound wave generator | |
| CN111397721A (en) | Method and system for absolute calibration of co-vibrating vector hydrophone based on water surface boundary vibration measurement technology | |
| CN110333295B (en) | Rock-soil core sample wave speed testing system and method | |
| CN210271424U (en) | Self-testing device for modal analysis | |
| Sun et al. | Natural frequency measurement of pipe vibration for vortex flowmeter | |
| CN208313903U (en) | A kind of device measuring chopped strand elasticity modulus | |
| CN201417314Y (en) | Tricomponent photoelectricity mixing integration acceleration seismic geophone | |
| JP4121426B2 (en) | Method and apparatus for measuring coefficient for vibration energy loss | |
| CN109470887A (en) | A kind of earthquake instrument system accelerometer Special testing device and method | |
| CN2572706Y (en) | Resonance frequency and mechanical compliance measurer for small bore electroacoustic device vibrating diaphragm | |
| CN108802195B (en) | Test device and method for measuring transverse wave velocity of core sample | |
| Niu et al. | Laboratory small-strain stiffness measurement using distributed acoustic sensing | |
| CN106320395A (en) | Low-strain double-speed signal averaging detection method for building hollow pile | |
| CN111141376A (en) | Ultrasonic wave interference phenomenon demonstration and sound velocity measurement device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200807 Termination date: 20210427 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |