CN113252515B - Test method of wet inter-particle liquid bridge stretching-compression mechanical property tester - Google Patents
Test method of wet inter-particle liquid bridge stretching-compression mechanical property tester Download PDFInfo
- Publication number
- CN113252515B CN113252515B CN202110555654.0A CN202110555654A CN113252515B CN 113252515 B CN113252515 B CN 113252515B CN 202110555654 A CN202110555654 A CN 202110555654A CN 113252515 B CN113252515 B CN 113252515B
- Authority
- CN
- China
- Prior art keywords
- liquid bridge
- liquid
- particles
- test
- stretching
- 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.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N13/00—Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects
- G01N13/02—Investigating surface tension of liquids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N13/00—Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects
- G01N13/02—Investigating surface tension of liquids
- G01N2013/0283—Investigating surface tension of liquids methods of calculating surface tension
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a test method of a wet inter-particle liquid bridge stretching-compression mechanical property tester, which comprises the steps of initial setting of the tester, liquid bridge test for controlling the volume of a liquid bridge, liquid bridge test for controlling the suction force of a matrix, and setting the types of the liquid bridge test, namely the liquid bridge stretching test, the liquid bridge compression test and the liquid bridge stretching-compression cycle test through a control system. The method of the invention can not only develop the stretching and compression of the liquid bridge and the cyclic test thereof in the set range under the condition of automatically and accurately controlling the volume of the liquid bridge or the absorption force of the matrix, but also monitor the change rule of the key geometric parameters of the meniscus in the whole process by combining an industrial electron microscope and a corresponding image processing method.
Description
Technical Field
The invention relates to an electromechanical device for geotechnical engineering, in particular to a method for determining interaction rules of wet particles and water in unsaturated soil, and particularly relates to a test method of a wet inter-particle liquid bridge stretching-compression mechanical property tester.
Background
The research of the hydraulic and mechanical properties of unsaturated soil is the foundation and key of geotechnical structure design and performance evaluation. The existing researches do not fully reveal the physical mechanism, and the macroscopic experiments under different experimental conditions reflect the unclear action mechanism, so that the design and construction optimization of the geotechnical structures are limited, and further the investment waste or potential safety hazard is caused. Therefore, unsaturated soil is regarded as a sphere wet particle aggregate, the moisture form among the wet particles is represented by a liquid bridge, and the knowledge of the mechanism of the unsaturated soil for micro-mechanics can be improved by researching the interaction mechanism of the wet particles and water, so that the internal requirement of the development of the unsaturated soil mechanics theory is met, and the external requirement of the construction of a geotechnical structure is met. Test equipment for obtaining mechanical characteristic parameters of wet inter-particle liquid bridges completely, stably and reliably is developed, and necessary data support can be provided for macroscopic hydraulic and mechanical characteristic characterization of unsaturated soil. To date, students mostly use Young-Laplace equation numerical solution and half-resolution-half-value method to study the geometric property and stress state of the wet inter-particle liquid bridge, and the two methods for indirectly simulating the mechanical property of the liquid bridge are limited in applicability, and the geometric property-mechanical property change rule and key parameter measurement method of the liquid bridge are also important contents for describing the micro-mechanical property of unsaturated soil. Therefore, it is important to directly measure the surface (meniscus) shape parameter of the liquid bridge and the capillary force evolution rule by adopting a test method. The existing technology for testing the mechanical properties of the liquid bridge basically takes the stretching of the liquid bridge as a test condition, and the interaction of the wet particles in the unsaturated soil and water mostly presents hysteresis phenomenon in the actual geotechnical engineering (such as the sudden drop of the water level of a soil dam and the sudden rise), so that the hysteresis mechanical properties of the liquid bridge among the wet particles are mainly controlled under the stretching-compressing condition on a microscopic scale, but the testing technology is freshly developed.
The existing wet inter-particle liquid bridge mechanical property testing equipment is mainly a wet inter-particle liquid bridge tensile mechanical property instrument for controlling the volume of a liquid bridge.
For example, patent publication Capillary Forces in Microassembly by Lambert, springer, modeling, formulation, experimenters, and Case Study, chapter 17 (month 4 of 2007) Test bed and characterization discloses a platform for testing mechanical properties of wet inter-particle liquid bridges, which can fix wet particles on a section of cantilever beam, allow deflection of the cantilever beam by stretching the liquid bridge between the wet particles, measure corresponding capillary force in combination with stiffness of the beam, and monitor changes in shape of the liquid bridge by imaging technique of an industrial electron microscope (CCD). However, the test platform cannot control and collect capillary force data in the liquid bridge compression process, and the liquid bridge formed by manually dripping liquid through a pipette among wet particles has poor symmetry, so that the initial condition of a liquid bridge tensile test is easily influenced.
The paper "Experimental Verification of Capillary Force and Water Retention between Uneven-Sized Spheres" published as Lu et al in Journal of Engineering Mechanics discloses a capillary force testing technique based on a glass fiber cantilever and a rigid capillary, which is configured with a high-precision controller, an optical microscope, a digital video microscope, and a geometric analysis is performed by image processing by measuring capillary force through deflection of the glass fiber cantilever when stretching a liquid bridge between particles. However, this technique cannot perform real-time capillary force recording, and compression of the liquid bridge and a liquid bridge stretch-compression cycle test cannot be achieved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a test method of a wet inter-particle liquid bridge stretching-compression mechanical property tester, by using the method, the liquid bridge stretching and compression and the cyclic test thereof in a set range can be carried out under the condition of automatically and accurately controlling the volume of the liquid bridge or the absorption of a matrix, and the change rule of the key geometric parameters of the meniscus can be monitored in the whole process by combining an industrial electron microscope and a corresponding image processing method.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a test method of a wet inter-particle liquid bridge tensile-compression mechanical property tester comprises the following steps:
1) Opening a control system and a data acquisition and image processing system, zeroing the high-precision balance value, and adjusting the video image displayed by the data acquisition and image processing system; the upper particles and the lower particles are respectively arranged on an upper support and a lower support, the upper particles are provided with holes, the lower support is arranged on a high-precision balance, and the upper support is connected with a position adjusting device;
starting a first stepping motor, driving a first lead screw to rotate by the first stepping motor, and driving a first screw nut to rotate by the rotation of the first lead screw, so as to drive a first pull rod fixed on the first screw nut to move up and down, and adjusting the spacing of particles; rotating the first knob to drive the first gear to rotate, and the first gear rotates to drive the first rack meshed with each other to move forwards and backwards in the groove; rotating the second knob to drive the second gear to rotate, and the second gear to rotate to drive the second rack meshed with each other to move left and right in the groove, so that the upper support fixed on the second rack is driven to adjust the front, back, left and right positions; in the process of adjusting the spacing of particles and the front, back, left and right positions of the upper support, real-time monitoring is carried out according to the data acquisition and image processing system;
2) Two tests were performed as follows:
A. the liquid bridge test for controlling the volume of the liquid bridge comprises the steps of firstly injecting liquid into a liquid bridge volume controller, controlling the liquid bridge volume controller to inject liquid into a pipeline through a control system, exhausting gas through an exhaust valve of the liquid bridge volume controller, then closing the exhaust valve of the liquid bridge volume controller, injecting liquid into an upper support through a pipeline communicated with the liquid bridge volume controller, and exhausting gas in an upper particle hole and the upper support; setting the liquid volume through a control system, and controlling a liquid bridge volume controller to inject liquid into the upward particles;
B. a liquid bridge test for controlling the suction force of the matrix is carried out, liquid is poured into the beaker, after the liquid fully flows into the pipeline, the corresponding stop valve is opened, so that the liquid flows into the measuring cylinder, and the measuring cylinder is used for reading the liquid level in the beaker; then a stop valve in a pipeline communicated with the upper support is opened, so that after liquid flows into the upper support, an exhaust valve of the upper support is opened, gas in the upper support is discharged, bubbles are prevented from being generated in a test, and then the exhaust valve is closed; the height of the beaker is regulated by a lifting table, liquid flows out from the upper particles to form a liquid bridge, and the suction force of the matrix is controlled according to the height difference between the liquid level of the beaker and the central section of the liquid bridge;
3) Setting a liquid bridge test type through a control system:
A. the liquid bridge tensile test, the control system controls the tension and compression device to downwards move the upper support, so that the upper particles and the lower particles are close to each other to form a liquid bridge, the upper particles and the lower particles are close to each other to be in a contact-non-contact state, the tensile rate is set, the data acquisition and image processing system records real-time data of the high-precision balance and displacement data and video images of the whole liquid bridge tensile process, the control system starts to stretch until the liquid bridge breaks, and then the control system stops to process the data and the images;
B. the method comprises the steps of a liquid bridge compression test, namely obtaining a liquid bridge stretching initial position and an end position to be broken in a liquid bridge stretching test step, respectively setting the liquid bridge stretching initial position and the end position to be broken as the end position and the initial position of the liquid bridge compression test through a control system, setting a stretching rate, recording real-time data of a high-precision balance and displacement data and video images of the whole liquid bridge compression process through a data acquisition and image processing system, starting the test through the control system, enabling upper particles to move from top to bottom to compress the liquid bridge, enabling the particles to be close to each other, and processing the data and the images through the data acquisition and image processing system;
C. the method comprises the steps of firstly carrying out a liquid bridge stretching test step to obtain a liquid bridge stretching initial position and a final position to be broken, respectively setting the liquid bridge stretching initial position and the final position to be broken as the initial position and the final position of the liquid bridge compression test through a control system, controlling a stretching device to downwards move an upper support through the control system, enabling upper particles and lower particles to be close to each other to form a liquid bridge, approaching the liquid bridge to a state of contact or non-contact, setting stretching speed and circulation times, recording real-time data of a high-precision balance and displacement data and video images of the whole liquid bridge stretching-compression process through a data acquisition and image processing system, starting the test through the control system, enabling the upper particles to circularly move, alternately carrying out stretching-compression circulation, and processing the data and the images through the data acquisition and image processing system.
The data and image processing includes liquid bridge capillary force calculation and image processing:
the calculation method of the capillary force of the liquid bridge comprises the following steps: recording placement of the undersupport and on the high precision balance prior to formation of the liquid bridgeIndication of lower particles
After the formation of the liquid bridge, recording the indication of the high-precision balance in the process of the stretching, compressing and stretching-compressing cycle test of the liquid bridge>
Capillary force->
Is formula (1):
the image processing method of the liquid bridge comprises the following steps: firstly, obtaining high-definition pictures of different positions of particles in a liquid bridge breaking process by using a first CCD and a second CCD, introducing the pictures into Image J software for binarization processing, improving the definition of the pictures until the liquid bridge and the particles are clear in outline and easy to distinguish, so that outline lines of the particles and outline lines of the liquid bridge can be conveniently drawn by using AutoCAD software, positioning the particles to determine a circle center, measuring the radius of the particles in the picture, and determining a picture scale by combining the actual radius of the particles; after the outline of the liquid bridge is determined, the outline of the liquid bridge is approximated by a circle by using a least square method, an optimal circle is selected through the fitness, and then the curvature radius of the meniscus is calculated by matching with a picture scale; the liquid bridge contour line is approximated by a circle by using a least square method, the center of the left and right optimal circles are connected, and the narrowest neck section of the liquid bridge is obtained by matching with a picture scale, so that the narrowest neck radius of the liquid bridge can be calculated.
Principle of selecting upper and lower particles and liquid:
the particles are soda lime glass polished spheres with physical properties of soil or sand grains, and the diameter range is 2-5 mm; when a small-volume liquid bridge test is carried out, water is selected from the liquid bridge for the test in order to simulate the actual condition of engineering; when a large-volume liquid bridge test is carried out, the liquid bridge selects glycerol for the test, and the specific indexes of the glycerol are as follows: at 25 ℃, the viscosity is 800 mPas, the surface tension is 61.9mN/m, and the relative density is 1.255.
Compared with the existing wet inter-particle liquid bridge mechanical property testing method, the method has the beneficial effects that:
1. the liquid bridge test under the condition of controlling the volume of the liquid bridge and the suction of the matrix can be respectively realized through the switch of the stop valve; when a liquid bridge test under the condition of controlling the volume of the liquid bridge is carried out, the volume of the liquid bridge is set through a control system, and a liquid bridge volume controller automatically injects quantitative liquid into an upper support; when the liquid bridge test under the condition of controlling the suction force of the matrix is carried out, the liquid level height difference is controlled by the matrix suction force control device, so that the suction force of the matrix is controlled.
2. The drawing and pressing device can be controlled by the control system, the type of the liquid bridge test, the drawing rate, the cycle times, the initial position and the final position of the drawing and the compression of the liquid bridge are set, and the drawing test and the compression test of the liquid bridge and the drawing-compression cycle test of the liquid bridge in a given range are realized.
3. The position of the upper support can be adjusted through the position adjusting device and the data acquisition and image processing system so as to form a liquid bridge which has good symmetry and does not influence the initial conditions of the test. Meanwhile, the data acquisition and image processing system is also used for acquiring mechanical parameter data and video images and processing software.
Drawings
FIG. 1 is a flow chart of an image processing method;
FIG. 2 is a schematic diagram of the system of the present invention;
FIG. 3 is an overview of the system of the present invention;
FIG. 4 is a block diagram of a liquid bridge volume controller;
FIG. 5 is a cross-sectional view A-A of FIG. 4;
FIG. 6 is a section B-B of FIG. 4;
FIG. 7 is a drawing of a drawing and pressing apparatus;
FIG. 8 is a front view of the position adjustment device;
FIG. 9 is a top view of the position adjustment device;
FIG. 10 is a front view of the upper support;
FIG. 11 is a left side view of the upper mount;
FIG. 12 is a top view of the upper support;
FIG. 13 is a front view of the lower support;
FIG. 14 is a top view of the lower support;
wherein, C, an actuating system, D, a matrix suction control device, E, a data acquisition and image processing system, 1, a control system, 2, a liquid bridge volume controller, 3, a first stop valve, 4, a pulling and pressing device, 5, a position adjusting device, 6, a first end straight-through joint, 7, a third stop valve, 8, a first three-way pipe joint, 9, a fifth stop valve, 10, a second end straight-through joint, 11, a beaker, a measuring cylinder, 13, a second stop valve, 14, a lower support, 15, an upper support, 16, a computer, 17, a third end through joint, 18, a second three-way pipe joint, 19, a fourth end through joint, 20, a first CCD,21, a high precision balance, 22, a second CCD,23, a fifth end through joint, 24, a fourth stop valve, 25, a sixth stop valve, 26, a lifting table, 27, a fifth end through joint, the first and second gear assembly comprises a seal head, 29, a third compression ring, 30, a T-shaped plunger, 31, a column casing, 32, a second compression ring, 33, a collar, 34, a first guide key, 35, a first guide cylinder, 36, a first compression ring, 37, a first bearing box, 38, a first step motor, 39, a second O-ring, 40, a second key ring, 41, a first O-ring, 42, a first screw, 43, a first screw, 44, a first key ring, 45, a second step motor, 46, a second bearing box, 47, a third key ring, 48, a second guide cylinder, 49, a second screw, 50, a second screw, 51, a pull rod, 52, a seal ring, 53, a fifth compression ring, 54, a fourth compression ring, 55, a second guide key, 56, a first rack, 57, a first gear, 58, a first knob, 59, a second knob, 60, a second gear, 61 and a second rack.
Detailed Description
The invention will be further described with reference to the drawings and examples.
The structures, proportions, sizes, etc. shown in the drawings attached hereto are for illustration purposes only and are not intended to limit the scope of the invention, which is defined by the claims, but rather by the claims. Also, the terms such as "upper," "lower," "left," "right," "middle," and "a" and the like recited in the present specification are merely for descriptive purposes and are not intended to limit the scope of the invention, but are intended to provide relative positional changes or modifications without materially altering the technical context in which the invention may be practiced.
As shown in fig. 1 to 14, the test method of the wet inter-particle liquid bridge tensile-compressive mechanical property tester comprises the following steps:
1) Opening the control system 1 and the data acquisition and image processing system E, zeroing the value of the high-precision balance 21, and adjusting the video image displayed by the data acquisition and image processing system E; the upper particles and the lower particles are respectively arranged on an upper support 15 and a lower support 14, the upper particles are provided with holes, the lower support 14 is arranged on a high-precision balance 21, and the upper support 15 is connected with a position adjusting device 5;
starting a second stepping motor 45, wherein the second stepping motor 45 drives a second lead screw 49 to rotate, and the second lead screw 49 rotates to drive a second nut 50 to rotate, so that a pull rod 51 fixed on the second nut is driven to move up and down, and the spacing between particles is regulated; rotating the first knob 58 drives the first gear 57 to rotate, and the first gear 57 rotates to drive the mutually meshed first rack 56 to move forwards and backwards in the groove; the second knob 59 is rotated to drive the second gear 60 to rotate, and the second gear 60 is rotated to drive the second rack 61 meshed with each other to move left and right in the groove, so that the upper support 15 fixed on the second rack 61 is driven to adjust the front, rear, left and right positions, and real-time monitoring is performed according to the data acquisition and image processing system E in the process of adjusting the spacing of particles and the front, rear, left and right positions of the upper support 15.
2) Two tests were performed as follows:
A. the liquid bridge test for controlling the liquid bridge volume is carried out by firstly injecting liquid into the liquid bridge volume controller 2, opening the first stop valve 3, closing the second to fourth stop valves 13, 7 and 24, controlling the liquid bridge volume controller 2 to inject liquid into a pipeline through the control system 1, discharging the gas of the liquid bridge volume controller 2 through the first stop valve 3, and then closing the first stop valve 3; opening the second stop valve 13 and the third stop valve 7 to inject liquid into the upper support 15 and discharge gas to the particle hole and the third stop valve 7, and then closing the third stop valve 7; the liquid volume is set through the control system 1, and the liquid bridge volume controller 2 is controlled to inject liquid into the upward particles;
B. a liquid bridge test for controlling the suction force of the matrix, wherein the second to sixth stop valves 13, 7, 24, 9 and 25 are closed, liquid is poured into the beaker 11, the fifth stop valve 9 and the sixth stop valve 25 are opened after the liquid fully flows into the pipeline, the liquid flows into the measuring cylinder 12, and the measuring cylinder 12 is used for reading the liquid level in the beaker; the fourth stop valve 24 is opened, the third stop valve 7 is opened after the liquid flows into the upper support 15, the gas in the upper support 15 is discharged, bubbles are prevented from being generated in the test, and then the third stop valve 7 is closed; the height of the beaker 11 is regulated by a lifting table 26, liquid flows out from the upper particles to form a liquid bridge, and the suction force of the matrix is controlled according to the height difference between the liquid level of the beaker and the central section of the liquid bridge;
3) Setting a liquid bridge test type through a control system:
A. in the liquid bridge stretching test, a control system 1 controls a tension and compression device 4 to downwards move an upper support 15 so that upper particles and lower particles are close to each other to form a liquid bridge, the upper particles and the lower particles are close to each other to be in a contact-non-contact state, the stretching speed is set, a data acquisition and image processing system E records real-time data of a high-precision balance and displacement data and video images of the whole liquid bridge stretching process, the control system 1 starts stretching until the liquid bridge is broken, and then the control system stops the stretching until the liquid bridge is broken, and software programs of the data acquisition and image processing system E process the data and the images;
B. the method comprises the steps of a liquid bridge compression test, namely obtaining a liquid bridge stretching initial position and a to-be-broken end position in the liquid bridge stretching test step, respectively setting the liquid bridge stretching initial position and the to-be-broken end position as the end position and the initial position of the liquid bridge compression test through a control system 1, setting a stretching rate, recording real-time data of a high-precision balance 21 and displacement data and video images of the whole liquid bridge compression process through a data acquisition and image processing system E, starting the test through the control system 1, moving upper particles from top to bottom to compress the liquid bridge, enabling the particles to be close to each other, and processing the data and the images through a software program of the data acquisition and image processing system E;
C. the liquid bridge stretching-compressing circulation test is carried out firstly, a liquid bridge stretching initial position and a final position to be broken are obtained in the liquid bridge stretching test step, the liquid bridge stretching initial position and the final position to be broken are respectively set as the initial position and the final position of the liquid bridge compressing test through the control system 1, the upper support 15 is controlled to move downwards through the control system 1 by the control pressure pulling device 4, upper particles and lower particles are close to each other to form a liquid bridge and are close to a contact non-contact state, the stretching speed and the circulation times are set, the data acquisition and image processing system E records real-time data of the high-precision balance 21 and displacement data and video images of the whole liquid bridge stretching-compressing process, the test is started through the control system 1, the upper particles are circulated, the stretching-compressing circulation is alternately carried out, and the data and the images are processed through a software program of the data acquisition and image processing system E.
The data and image processing includes calculation of liquid bridge capillary force and image processing of liquid bridge capillary force.
The calculation method of the liquid bridge capillary force comprises the following steps: registration of placement of lower support 14 and lower particles on high precision balance 21 prior to formation of liquid bridge
After the formation of the liquid bridge, the indication of the high-precision balance 21 is recorded during the liquid bridge stretching, compressing, stretching-compressing cycle test>
Capillary force->
Is formula (1):
the processing method of the liquid bridge image (the flow chart of the image processing method in fig. 1) is as follows: firstly, obtaining high-definition pictures of different positions of particles in a liquid bridge breaking process by using a first CCD and a second CCD, introducing the pictures into Image J software for binarization processing, improving the definition of the pictures until the liquid bridge and the particles are clear in outline and easy to distinguish, so that outline lines of the particles and outline lines of the liquid bridge can be conveniently drawn by using AutoCAD software, positioning the particles to determine a circle center, measuring the radius of the particles in the picture, and determining a picture scale by combining the actual radius of the particles; after the outline of the liquid bridge is determined, the outline of the liquid bridge is approximated by a circle by using a least square method, an optimal circle is selected through the fitness, and then the curvature radius of the meniscus is calculated by matching with a picture scale; the liquid bridge contour line is approximated by a circle by using a least square method, the center of the left and right optimal circles are connected, and the narrowest neck section of the liquid bridge is obtained by matching with a picture scale, so that the narrowest neck radius of the liquid bridge can be calculated.
The principle of selecting upper and lower particles and liquid is as follows: the particles are soda-lime glass polished spheres with physical properties of soil or sand grains, the diameter range is 2-5 mm, the liquid bridge is greatly influenced by gravity when the particle size is too large, and the liquid dropping operation is difficult when the particle size is too small; when a small-volume liquid bridge test is carried out, water is selected from the liquid bridge for the test in order to simulate the actual condition of engineering; when carrying out bulky liquid bridge test, because water surface tension is less makes the difficult shaping of liquid bridge and easy evaporation, the liquid bridge selects the glycerol to carry out the test, and the concrete index of glycerol is: the viscosity (25 ℃ C.) was 800 mPas, the surface tension was 61.9mN/m, and the relative density was 1.255.
As shown in fig. 1 and 2, the wet inter-particle liquid bridge stretching-compression mechanical property tester comprises an actuating system C capable of axially stretching and compressing, a liquid bridge volume controller 2, a substrate suction control device E, a control system 1 and a data acquisition and image processing system D. The control system 1 respectively controls the actuating system C and the liquid bridge volume controller 2, the liquid bridge volume controller 2 is connected with the actuating system C, the actuating system C is connected with the substrate suction control device E, and the data acquisition and image processing system D acquires the data generated by the actuating system C;
the actuating system C comprises a pulling and pressing device 4, a position adjusting device 5, an upper support 15 and a lower support 14 which are arranged in sequence from top to bottom. The liquid bridge volume controller 2 comprises a cylinder with an opening at the front end, an end socket 28 with a central opening is arranged at the opening end of the cylinder, a power mechanism is arranged at the rear end of the cylinder, and the power mechanism is connected with a T-shaped plunger mechanism in the shell and can drive the T-shaped plunger mechanism to reciprocate; a sealing ring is embedded in the inner side of the cylinder body, so that the cylinder body, the sealing head and the T-shaped plunger form an independent closed space, and liquid in the independent closed space can be injected out when the T-shaped plunger moves upwards;
the position adjusting device 5 comprises an upper group of gear rack mechanisms and a lower group of gear rack mechanisms which are fixedly connected, and racks of the two groups of gear rack mechanisms are mutually perpendicular; the racks of the upper group of gear rack mechanisms are fixedly connected with the bottom of the pulling and pressing device 4, the racks of the lower group of gear rack mechanisms are fixedly connected with the upper support 15, and the upper support and the lower support are correspondingly arranged in a matching way.
As shown in fig. 2 and 3, the matrix suction control device E, the liquid bridge volume controller 2 and the actuating system C are the core parts of the instrument, and comprise a pulling and pressing device 4, a position adjusting device 5, an upper support 15 and a lower support 14; the lower part of the pulling and pressing device 4 is connected with the position adjusting device 5, the lower part of the position adjusting device 5 is connected with the upper support 15, the left opening of the upper support 15 is connected with the first port of the second three-way pipe joint 18 through the fourth end through joint 19 and the second stop valve 13, the second port of the second three-way pipe joint 18 is connected with the liquid bridge volume controller 2 through the third end through joint 17, the third port is connected with the first stop valve 3, the right opening of the upper support 15 is connected with the first port of the first three-way pipe joint 8 through the fifth end through joint 23 and the fourth stop valve, one port of the other two ports of the first three-way pipe joint 8 is communicated with the beaker 11 through the fifth stop valve 9 and the second end through joint 10, the other port is communicated with the measuring cylinder 12 through the sixth stop valve 25 and the end through joint 27, the beaker 11 is arranged on the lifting table 26, and the beaker 11, the measuring cylinder 12 and the lifting table 26 form the matrix suction control device E.
As shown in fig. 4 to 6, the liquid bridge volume controller 2 is composed of a head 28, a third press ring 29, a T-shaped plunger 30, a column casing 31, a second press ring 32, a collar 33, a first guide key 34, a first guide casing 35, a first press ring 36, a first bearing box 37, a first stepping motor 38, a second key ring 40, a first nut 42, a first screw 43, and a first key ring 44.
The first stepper motor 38 is connected with the first lead screw 43 through the first bearing box 37 and drives the first lead screw 43 to rotate, the first lead screw 43 penetrates through the first screw 42, the first lead screw 43 and the first screw 42 are matched for use, corresponding spiral lines are formed on the outer side of the first lead screw 43 and the inner side of the first screw 42, the left side of the first screw 42 is connected with the first guide key 34, when the first stepper motor 38 drives the first lead screw 43 to rotate, the first screw 42 moves up and down along with the first lead screw, the first guide cylinder 35 is arranged outside the first screw 42, the first guide cylinder 35 is connected with the first bearing box 37 through the first press ring 36 and the first key ring 44, and the first key ring 44 is nested in a groove on the outer side of the lower end of the first guide cylinder 35 and then fixed by the first press ring 36; the inner side of the first guide cylinder 35 is provided with a guide groove corresponding to the first guide key 34, so that the first screw 42 cannot rotate along with the first screw 43 when moving vertically in the first guide cylinder 35; the T-shaped plunger 30 is arranged on the first screw 42 and moves up and down along with the movement of the first screw 42; the column casing 31 is connected with the first guide casing 35 through the collar 33 and the second compression ring 32, the collar 33 is nested outside the first guide casing 35 and the column casing 31, and then the column casing 31 is fixed by the second compression ring 32; the seal head 28 is connected with the column casing 35 through a second key ring 40 and a third press ring 29, the second key ring 40 is nested in a groove on the outer side of the upper end of the column casing 35, and then the seal head is fixed by the third press ring 29; the central opening of the seal head 28 is used for discharging liquid; two first O-shaped sealing rings 41 are embedded in the inner side of the lower end of the column casing 35, and a second O-shaped sealing ring 39 is embedded in the inner side of the upper end of the column casing 35, so that an independent airtight space is formed among the column casing 35, the sealing head 28 and the T-shaped plunger 30, and liquid can be injected when the T-shaped plunger 30 is upwards.
As shown in fig. 7, the pulling and pressing device 4 is composed of a second stepping motor 45, a second bearing housing 46, a third key ring 47, a second guide cylinder 48, a second lead screw 49, a second nut 50, a pull rod 51, a seal ring 52, a fifth pressing ring 53, a fourth pressing ring 54, and a second guide key 55.
The second stepping motor 45 is connected with a second lead screw 49 through an inner bearing of a second bearing box 46, the second lead screw 49 penetrates through a second screw nut 50, the second lead screw 49 and the second screw nut 50 are matched for use, the outer side of the second lead screw 49 and the inner side of the second screw nut 50 are provided with corresponding spiral lines, the right side of the second screw nut 50 is connected with a second guide key 55, when the second stepping motor 45 drives the second lead screw 49 to rotate, the second screw nut 50 moves up and down along with the second lead screw, a second guide cylinder 48 is arranged outside the second screw nut 50, the second guide cylinder 48 is connected with the second bearing box 46 through a fourth compression ring 54 and a third compression ring 47, the third compression ring 47 is nested in a groove at the outer side of the upper end of the second guide cylinder 48, and then the third compression ring 54 is used for fixing; the inner side of the second guide cylinder 48 is provided with a guide groove corresponding to the second guide key 55, so that the second screw 50 does not rotate along with the second lead screw 49 when moving vertically in the second guide cylinder 48; the pull rod 51 is mounted on the second nut 50 and moves up and down along with the movement of the second nut 50; the seal ring 52 is fitted inside the upper end of the guide cylinder and then fixed by a fifth press ring 53. The pulling and pressing device is connected with the position adjusting device 5 through a pull rod 51, and the control system 1 controls the pulling and pressing device 4 to apply vertical displacement.
As shown in fig. 8 and 9, the position adjustment device 5 includes a first rack 56, a first gear 57, a second knob 58, a first knob 59, a second gear 60, and a second rack 61. The components are all arranged in the shell, and the first knob 59 is supported in a longitudinal groove on the shell and can reciprocate along the longitudinal groove; the second knob 58 is supported in a transverse slot mounted to the housing and is reciprocally movable along the transverse slot.
The components are divided into two groups, a first rack 56, a first gear 57 and a first knob 59 are respectively connected with the first knob 59 and the second knob 58, a second rack 61, a second gear 60 and the second knob 58 are respectively connected with the first rack 61, the second rack 61 is mutually vertically arranged, each group of the first rack 57 is meshed with the first rack 56, the second rack 61 is meshed with the second gear 60, the first rack 56 is fixed on the second rack 61, the upper support 15 is fixed below the second rack 61, the first gear 57 and the second gear 60 are respectively connected with the first knob 59 and the second knob 58, the first rack 59 and the second gear 60 are driven to linearly move by rotating the first gear 57 and the second gear 61 through the first knob 59 and the second knob 58, so that the front-back and left-right movement of the upper support 15 is controlled, the first rack 56 is connected with the pull rod 51 of the tension-compression device 4, the second rack 61 is connected with the upper support 15, the upper support 15 and the image processing system D is combined to center the upper support 15 and the lower support 14, and a liquid bridge which has good symmetry and does not influence initial conditions in the test.
As shown in fig. 2, the control system 1 controls the tension and compression device 4 to set the test type, the tension rate, the initial and final positions, and the number of cycles to perform the liquid bridge test.
As shown in fig. 2, 3 and 10-14, the upper opening of the upper support 15 is connected with the third stop valve 7 through the first end through joint 6, when the third stop valve 7 is opened, the gas in the upper support 15 is discharged, so that bubbles are prevented from being generated in the test, and then the third stop valve 7 is closed; the lower opening is used for installing upper particles and injecting liquid into the upper particles; the left opening is connected with the liquid bridge volume controller 2 through a fourth end straight-through joint 19, and a passage is formed by switching a second stop valve 13, so as to carry out a liquid bridge test under the condition of controlling the volume of the liquid bridge; the right side opening is connected with a substrate suction control device E through a fifth end straight-through joint 23, and a passage is formed by opening and closing a fourth stop valve 24, so that a liquid bridge test under the condition of controlling the suction of the liquid bridge substrate is performed.
As shown in fig. 2 and 3, the data acquisition and image processing system mainly comprises a computer 16, a high-precision balance 21, a first CCD20 and a second CCD 22.
The lower support 14 is placed on a high-precision balance 21, the high-precision balance 21, a first CCD20 and a second CCD22 are connected with a computer 16, and mechanical parameter data and video images in the liquid bridge test process are recorded and processed through a software program.
As shown in fig. 2, 10-14, two spherical particles are respectively mounted on the upper support 15 and the lower support 14 during the test, the upper spherical particles are provided with holes for injecting liquid, the positions of the particles are observed through the data acquisition and image processing system D, and the two particles are centered by the position adjusting device 5, so that a liquid bridge with good symmetry and no influence on the initial conditions of the test is formed.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (6)
1. The test method of the wet inter-particle liquid bridge tensile-compressive mechanical property tester is characterized by comprising the following steps of:
1) The initial setting of the tester, the upper and lower particles to be tested are respectively installed in the tester, and are adjusted in place and monitored in real time;
2) Two tests were performed as follows:
A. the liquid bridge test for controlling the volume of the liquid bridge comprises the steps of firstly injecting liquid into a liquid bridge volume controller, controlling the liquid bridge volume controller to inject liquid into a pipeline by a control system, exhausting gas through an exhaust valve of the liquid bridge volume controller, then closing the exhaust valve of the liquid bridge volume controller, injecting liquid into an upper support through a pipeline communicated with the liquid bridge volume controller, and exhausting gas in an upper particle hole and the upper support; setting the liquid volume through a control system, and controlling a liquid bridge volume controller to inject liquid into the upward particles;
B. a liquid bridge test for controlling the suction force of the matrix, pouring liquid into a beaker, and opening a corresponding stop valve after the liquid fully flows into a pipeline so as to enable the liquid to flow into a measuring cylinder; then a stop valve in a pipeline communicated with the upper support is opened, after liquid flows into the upper support, an exhaust valve of the upper support is opened, gas in the upper support is discharged, bubbles are prevented from being generated in a test, and then the exhaust valve is closed; the height of the beaker is regulated by a lifting table, liquid flows out from the upper particles to form a liquid bridge, and the suction force of the matrix is controlled according to the height difference between the liquid level of the beaker and the central section of the liquid bridge;
3) Setting a liquid bridge test type through a control system:
A. the liquid bridge tensile test, the control system controls the tension and compression device to downwards move the upper support, so that the upper particles and the lower particles are close to each other to form a liquid bridge, the upper particles and the lower particles are close to each other to be in a contact-non-contact state, the tensile rate is set, the data acquisition and image processing system records real-time data of the high-precision balance and displacement data and video images of the whole liquid bridge tensile process, the control system starts to stretch until the liquid bridge breaks, and then the control system stops to process the data and the images;
b, a liquid bridge compression test is carried out, a liquid bridge stretching initial position and an end position to be broken are obtained in the liquid bridge stretching test step, the liquid bridge stretching initial position and the end position to be broken are respectively set to be the end position and the initial position of the liquid bridge compression test through a control system, the stretching rate is set, real-time data of a high-precision balance and displacement data and video images of the whole liquid bridge compression process are recorded by a data acquisition and image processing system, the test is started through the control system, the upper particles move the compressed liquid bridge from top to bottom, the particles are close to each other, and the data and the images are processed through the data acquisition and image processing system;
C. the method comprises the steps of firstly carrying out a liquid bridge stretching test step to obtain a liquid bridge stretching initial position and a final position to be broken, respectively setting the liquid bridge stretching initial position and the final position to be broken as the initial position and the final position of the liquid bridge compression test through a control system, controlling a stretching device to downwards move an upper support through the control system, enabling upper particles and lower particles to be close to each other to form a liquid bridge, approaching the liquid bridge to a state of contact or non-contact, setting stretching speed and circulation times, recording real-time data of a high-precision balance and displacement data and video images of the whole liquid bridge stretching-compression process through a data acquisition and image processing system, starting the test through the control system, enabling the upper particles to circularly move, alternately carrying out stretching-compression circulation, and processing the data and the images through the data acquisition and image processing system.
2. The test method according to claim 1, wherein in the step 1), the control system and the data acquisition and image processing system are turned on, the high-precision balance value is zeroed, and the video image displayed by the data acquisition and image processing system is adjusted; the upper particles and the lower particles are respectively arranged on an upper support and a lower support, the upper particles are provided with holes, the lower support is arranged on a high-precision balance, and the upper support is connected with a position adjusting device;
starting a second stepping motor, driving a second screw rod to rotate by the second stepping motor, driving a second screw nut to rotate by the second screw rod, and driving a pull rod fixed on the pull rod to move up and down so as to adjust the spacing of particles; rotating the first knob to drive the first gear to rotate, and the first gear rotates to drive the first rack meshed with each other to move forwards and backwards in the groove; the second knob is rotated to drive the second gear to rotate, and the second gear rotates to drive the mutually meshed second racks to move left and right in the groove, so that the upper support fixed on the second racks is driven to adjust the front, back, left and right positions, and the adjustment comprises a first knob, the second knob, two groups of mutually meshed gears and racks; in the process of adjusting the spacing of particles and the front, back, left and right positions of the upper support, real-time monitoring is performed according to the data acquisition and image processing system.
3. The method of claim 1, wherein the processing of the data and images comprises calculation of liquid bridge capillary forces and image processing.
4. A test method according to claim 3, wherein the liquid bridge capillary force is calculated by: registration of placement of lower support and lower particles on high precision balance prior to formation of liquid bridge
After the formation of the liquid bridge, recording the indication of the high-precision balance in the process of the stretching, compressing and stretching-compressing cycle test of the liquid bridge>
Capillary force->
Is formula (1):
5. a test method according to claim 3, characterized in that the liquid bridge image is processed as follows: firstly, obtaining high-definition pictures of different positions of particles in a liquid bridge breaking process by using a first industrial electron microscope and a second industrial electron microscope, introducing the pictures into Image J software for binarization processing, improving the definition of the pictures until the liquid bridge and the particles are clear in outline and easy to distinguish, so that outline lines of the particles and outline lines of the liquid bridge are drawn by using AutoCAD software, positioning the particles to determine a circle center, measuring the radius of the particles in the pictures, and determining a picture scale by combining the actual radius of the particles; after the outline of the liquid bridge is determined, the outline of the liquid bridge is approximated by a circle by using a least square method, an optimal circle is selected through the fitness, and then the curvature radius of the meniscus is calculated by matching with a picture scale; the liquid bridge contour line is approximated by a circle by using a least square method, the center of the left and right optimal circles are connected, and the narrowest neck section of the liquid bridge is obtained by matching with a picture scale, so that the narrowest neck radius of the liquid bridge can be calculated.
6. The method according to claim 1, wherein the upper and lower particles and the liquid are selected according to the following principle:
the particles are soda lime glass polished spheres with physical properties of soil or sand grains, and the diameter range is 2-5 mm; when a small-volume liquid bridge test is carried out, water is selected from the liquid bridge for the test in order to simulate the actual condition of engineering; when a large-volume liquid bridge test is carried out, the liquid bridge selects glycerol for the test, and the specific indexes of the glycerol are as follows: at 25 ℃, the viscosity is 800 mPas, the surface tension is 61.9mN/m, and the relative density is 1.255.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110555654.0A CN113252515B (en) | 2021-05-21 | 2021-05-21 | Test method of wet inter-particle liquid bridge stretching-compression mechanical property tester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110555654.0A CN113252515B (en) | 2021-05-21 | 2021-05-21 | Test method of wet inter-particle liquid bridge stretching-compression mechanical property tester |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113252515A CN113252515A (en) | 2021-08-13 |
| CN113252515B true CN113252515B (en) | 2023-06-23 |
Family
ID=77183462
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110555654.0A Active CN113252515B (en) | 2021-05-21 | 2021-05-21 | Test method of wet inter-particle liquid bridge stretching-compression mechanical property tester |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113252515B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102081030A (en) * | 2010-04-08 | 2011-06-01 | 上海海事大学 | Geotechnical model test system based on macro-micro mechanics as well as elaboration test method |
| CA2982289A1 (en) * | 2016-10-13 | 2018-04-13 | Alidad Amirfazil | Liquid lens with a tunable focus, and method of fabrication of same |
| CN208832873U (en) * | 2018-09-12 | 2019-05-07 | 世贸天阶制药（江苏）有限责任公司 | A kind of heated-air circulation oven |
| CN111413263A (en) * | 2020-05-06 | 2020-07-14 | 西安理工大学 | Three-axis instrument for jointly measuring unsaturated soil water and gas movement |
-
2021
- 2021-05-21 CN CN202110555654.0A patent/CN113252515B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102081030A (en) * | 2010-04-08 | 2011-06-01 | 上海海事大学 | Geotechnical model test system based on macro-micro mechanics as well as elaboration test method |
| CA2982289A1 (en) * | 2016-10-13 | 2018-04-13 | Alidad Amirfazil | Liquid lens with a tunable focus, and method of fabrication of same |
| CN208832873U (en) * | 2018-09-12 | 2019-05-07 | 世贸天阶制药（江苏）有限责任公司 | A kind of heated-air circulation oven |
| CN111413263A (en) * | 2020-05-06 | 2020-07-14 | 西安理工大学 | Three-axis instrument for jointly measuring unsaturated soil water and gas movement |
Non-Patent Citations (1)
| Title |
|---|
| 粗颗粒间液桥毛细力演化规律的动态计算方法;张昭;刘奉银;齐吉琳;柴军瑞;;岩土力学(第08期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113252515A (en) | 2021-08-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107478800B (en) | Gravity casting simulates testing stand | |
| CN100573095C (en) | A kind of true triaxil tester of three-dimensional independent loads pressure chamber structure | |
| CN201378166Y (en) | Test device for studying permeable destruction phenomenon | |
| CN206920243U (en) | A kind of uniaxial compression test device | |
| CN109374856B (en) | Test device for observing three-dimensional space deformation in transparent soil model and using method | |
| CN104374625A (en) | Semi-automatic multifunctional soil test sample compaction device | |
| CN204255718U (en) | A kind of semi-automatic multifunction soil test pressure-like machine | |
| CN110095347B (en) | Strain control type unsaturated soil three-axis stretching instrument | |
| CN113252515B (en) | Test method of wet inter-particle liquid bridge stretching-compression mechanical property tester | |
| CN207366545U (en) | Gravity casting simulates testing stand | |
| CN113237797B (en) | Wet inter-particle liquid bridge stretching-compression mechanical property tester | |
| CN101514978A (en) | Test method for studying phenomenon of permeable damage on soil body and test device thereof | |
| CN102455344B (en) | Method for multi-connected sludge specific resistance measurement device | |
| CN116735844B (en) | Device and method for rapidly measuring grouting rate of semi-flexible pavement | |
| CN117147334A (en) | Energy pile-soil interface shear creep characteristic simulation device, test system and use method thereof | |
| US3433056A (en) | Permeability cell | |
| CN207619916U (en) | Simulate experimental provision of the xenobiotic pollutants to sediment incipient motion and settlement influence | |
| CN218470378U (en) | 3D prints concrete constructability testing machine | |
| CN112255135B (en) | Device and method for testing liquid film evaporation power | |
| CN108020298A (en) | Embedded Mold Steel Level sensor off-line test system | |
| CN109187924B (en) | Miniature soil sample hydraulic consolidation loading system | |
| CN110057681B (en) | Device and method for measuring rock type II fracture energy and observing rock surface velocity field | |
| CN111829920A (en) | Device for measuring resistance coefficient of crop blade | |
| CN210154925U (en) | Roadbed soil compression resistance modulus of resilience testing arrangement | |
| CN109060851B (en) | Micro loess unsaturated suction control loading device and method for separable pressure chamber |
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 |