A static and dynamic liquid bridge measurement system and method between particles

Abstract

The present invention discloses a system and method for measuring static and dynamic liquid bridges between three or two ellipsoidal particles, belonging to the field of micro-force measurement. The system includes a support module, a displacement adjustment module, a liquid bridge volume control module, a micro-force measurement module, a data acquisition and image processing module, and a particle placement device. By measuring the horizontal and vertical liquid bridge suction between particle groups using the deflection changes at the bottom end of a down-rigged beam and a microbalance, the system enables microscopic measurement of the morphology and mechanical properties of liquid bridges between three or two ellipsoidal particles at different inclination angles. This system provides experimental insights for conducting more complex particle group suction studies and offers a more realistic experimental method for studying microscopic soil-water characteristics.

Description

Technical Field

[0001] The present invention relates to a system and method for measuring static and dynamic liquid bridges between particles, and in particular to a system and method for measuring static and dynamic liquid bridges between three particles or double ellipsoid particles, belonging to the technical field of micro-force measurement. Background Art

[0002] Liquid bridges are a natural phenomenon formed when interstitial liquid exists between wet particles, resulting from the interaction of solid, liquid, and gas phases at their interfaces. Their microscopic hydraulic properties are fundamental to studying the capillary phenomena and mechanical properties of unsaturated soils. Current tests of liquid bridge forces primarily focus on double-spherical particles. When the water content is high, adjacent liquid bridges overlap, reaching a "rope-like" stage. The merged liquid bridges can connect two or even more particles simultaneously. In this case, the double-particle liquid bridge model is no longer applicable, necessitating the development of a three-particle or particle group contact model. Furthermore, in their natural state, soil particles are often irregularly and asymmetrically distributed. Their geometry and particle contact state influence the distribution of liquid in the pores, pore water pressure, and surface tension, and thus the strength and deformation properties of the soil. However, existing experiments have mostly been based on spherical or round particles, which fail to describe the true particle shape. To more accurately describe non-spherical particles, researchers have attempted to employ tetrahedrons, ellipsoids, hyperellipsoids, polyhedrons, and non-uniform free radical spline surfaces for true approximation. Among them, ellipsoids or extended superellipsoids have rich shape feature representations, such as elongation, flatness, angularity and asymmetry, and are widely used in the three-dimensional reconstruction of the true shape of particles.

[0003] Since the liquid bridge force is very small and changes rapidly, it is only significant when the particle size is <3mm. Micro-force measuring instruments suitable for physical experiments are often expensive, and testing devices are rare. Microbalance method or cantilever beam method are mainly used. A Chinese invention patent (CN113252515A) discloses a test device and method for the tensile-compression mechanical properties of liquid bridges between wet particles. It can carry out liquid bridge stretching, compression and cyclic tests within a set range under the condition of automatic control of liquid bridge volume or matrix suction. At the same time, an industrial electron microscope is used to monitor the changes in the key geometric parameters of the curved liquid surface in combination with image processing methods. A Chinese invention patent (CN112986059A) discloses a static and dynamic liquid bridge observation system and method between two spherical particles. The invention is based on the cantilever beam micro-force measurement method, which converts the liquid bridge force measurement into the change in the deflection of the cantilever beam end, realizing static and dynamic liquid bridge force measurement. Both of the above invention devices can measure the liquid bridge force between particles and its morphological changes during the tensile fracture process, but they are all centered on double spherical particles and cannot analyze multiple particles and irregular particles. In view of the above background, the present invention proposes a test device that can measure the mechanical properties of liquid bridges between three particles or bi-ellipsoidal particles, in order to provide an experimental means for studying the microscopic soil-water characteristics between matrix suction and volumetric moisture content. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention aims to provide a static and dynamic liquid bridge measurement system and method between three particles or double ellipsoid particles. By changing the deflection of the bottom end of the downward beam and using a microbalance, the horizontal and vertical liquid bridge suctions between the particle groups are measured respectively. This realizes the microscopic measurement of the morphology and mechanical properties of the liquid bridges between three particles or double ellipsoid particles under different inclination conditions, provides an experimental idea for conducting more complex particle group suction research, and provides a more realistic experimental testing means for studying the microscopic soil-water characteristic laws.

[0005] The present invention uses cantilever beam micro-force measurement technology to convert the rapidly changing and tiny liquid bridge force measurement into changes in the deflection of the cantilever beam end, indirectly achieving accurate measurement of the horizontal force of the liquid bridge, and then combining it with the vertical force read by the microbalance to realize the mechanical properties of the multi-particle liquid bridge.

[0006] The present invention provides a static and dynamic liquid bridge measurement system between particles, comprising a support module, a displacement adjustment module, a liquid bridge volume control module, a micro-force measurement module, a data acquisition and image processing module, and a particle placement device;

[0007] The support module includes a vibration reduction platform and an L-shaped cantilever beam. The vibration reduction platform and the L-shaped cantilever beam are provided in two groups on the left and right, with the same structure. One or both groups can be selected for the experiment as needed. The L-shaped cantilever beam is provided above the vibration reduction platform, and the cantilever beam is supported by a microbalance and a first U-shaped slot. The displacement adjustment modules are respectively connected to the cantilever beam.

[0008] The displacement adjustment module includes a horizontal adjustment device and a height adjustment device; the horizontal adjustment device includes a worm gear, a worm, and a displacement block. The worm gear and the worm are connected at the end of the cantilever beam, and the displacement block is connected at the end of the worm gear. The horizontal cantilever beam is connected to the displacement block through a transversely arranged worm gear. By rotating the worm gear, the worm gear and the displacement block are driven to move horizontally; the height adjustment device includes two sets of devices, coarse adjustment and fine adjustment. The coarse adjustment device includes an adjustment bracket, a clip, and a lower extension beam. The adjustment accuracy is 5mm. The lower extension beam is arranged at the end of the displacement block of the horizontal adjustment device The lower extending beam is composed of a vertically arranged rectangular plate and a rectangular plate vertically connected at the bottom, and the side surface is an inverted T-shaped structure; the lower extending beam is fixed to the displacement block by a clamp, and the bottom of the rectangular plate at the bottom of the lower extending beam is bonded to the sample particles; the vertical position of the lower extending beam and the upper particles is adjusted by loosening the clamp; the adjustment bracket is located at the bottom of the particle placement device, and the vertical position of the lower particle can also be controlled by manually adjusting the bracket; the fine adjustment device includes an electric bevel gear lifting platform, which is placed above the adjustment bracket; the adjustment accuracy of the fine adjustment device is 0.08mm.

[0009] The liquid bridge volume control module includes a micro-propulsion pump and a syringe needle. The micro-propulsion pump is connected to a computer via a controller. This module is placed behind the particle placement device. The micro-propulsion pump controls the syringe needle to add a droplet at the apex of the particle's spherical cap to form a liquid bridge.

[0010] The particle placement device includes a second U-shaped slot located above the electric bevel gear lifting platform, and the upper particles to be tested are in contact with the downward extension beam; the lower particles to be tested are placed in the second U-shaped slot, and the U-shaped slot is used to fix the particles to be tested by adjusting the slot spacing through the telescopic plate.

[0011] The data acquisition and image processing module includes a high-speed camera that records the morphological changes of the interparticle liquid bridge during its formation, stretching, and rupture through photos and videos. The high-speed camera is mounted on a height-adjustable camera stand with its field of view aligned with the particle group to be tested.

[0012] The micro-force measurement module includes a first microbalance and a second microbalance; wherein, the first microbalance and the second microbalance are placed on a vibration reduction table, and a first U-shaped slot is fixed on the balance weighing plate. The U-shaped slot is used to adjust the slot spacing through a telescopic plate to support the cantilever beam.

[0013] The controller is connected to the computer and can control the operating device after installing the corresponding driver.

[0014] Furthermore, the L-shaped outrigger beam is a horizontal beam, the end of which is bent into an L shape and fixed to the vibration reduction platform by bolts, and the vibration reduction platform is arranged symmetrically on the left and right.

[0015] Furthermore, one end of the worm of the level adjustment device is locked in the cantilever beam, and the other end is fixedly connected to the displacement block. The worm wheel is fixed to the end of the cantilever beam by bolts.

[0016] Furthermore, the electric bevel gear lifting platform is connected to a computer to achieve precise vertical movement of the lower particles. Specifically, the electric bevel gear lifting platform includes a glass tempered plate, anti-slip pads, a motor, an elevator, a connecting shaft, and a lead screw. The glass tempered plate is a rectangular structure with four anti-slip pads evenly distributed below it. The bottom of the anti-slip pads is connected to the elevator via a lead screw. The four elevators are connected by connecting shafts and are all connected to the motor, providing power.

[0017] Furthermore, the adjustment bracket is a high-precision small scissor-type lifting workbench, which is used as a part of the coarse adjustment device to adjust the vertical displacement of the sample particles.

[0018] The present invention can be used for measuring static and dynamic liquid bridges between three particles or double ellipsoid particles.

[0019] When three particles are used as the research object, the three-particle test is composed of three spherical particles, the centers of which are located in the same vertical plane, two of which are located at the top and one at the bottom. The particle placement device of the above-mentioned measurement system includes: a second U-shaped slot and a third microbalance; the two upper spherical particles are respectively glued to the bottom of the bottom plate of the two downward extending beams, and the lower spherical particle is placed in the second U-shaped slot. The second U-shaped slot is located above the third microbalance, and the third microbalance is set above the electric bevel gear lifting platform.

[0020] Furthermore, in order to facilitate the adjustment of the two upper particles, the heights of the two lower extension beams are staggered; because the particles are very close to each other, it is convenient for installation and operation, and it prevents the left and right vibration damping platforms from contacting each other and hindering the movement of the particles.

[0021] A laser rangefinder is also provided on the side of the three-particle placement device; the laser rangefinder is arranged on the left and right sides of the downward extending beam, and the laser light spot is aligned with the midpoint of the bottom end of the downward extending beam.

[0022] When studying bi-ellipsoidal particles, the bi-ellipsoidal test particles consist of two ellipsoidal particles, one above and one below, with their centers aligned on the same vertical line. The upper particle is cemented to the bottom of the downward beam, while the lower particle is held within a U-shaped slot. The particle placement device of the measurement system includes a second U-shaped slot and an angle adjustment mechanism. The upper ellipsoidal particle is secured below the bottom plate of the downward beam, while the lower ellipsoidal particle is secured within the second U-shaped slot. An angle adjustment mechanism is provided below the second U-shaped slot. The angle adjustment mechanism includes a worm and worm gear mechanism, a rotating gear, an angle plate, a support plate, an outer ring, and an encapsulating housing. The support plate is a steel square plate for placing particles, and a worm gear mechanism is provided at the bottom; the outer ring is sleeved on the outer edge of the rotating gear and is connected to the bottom of the support plate by bolts to form a whole, so as to keep the worm gear and the gear in close contact at all times; the worm gear is located above the rotating gear and is tightly engaged with it, and the worm gear is driven to rotate by rotating the worm, thereby causing the support plate to rotate along the outer edge of the gear; the surfaces of the encapsulating shell of the worm gear mechanism and the rotating gear below are respectively provided with pointers and angle scales for indicating the inclination angle of the lower particles.

[0023] It should be noted that when double ellipsoid particles are used as the research object, only the support module and displacement adjustment module on one side of the support device participate in the experiment.

[0024] The structures of the first U-shaped slot and the second U-shaped slot are the same; both are composed of a left U-shaped plate, a right U-shaped plate, a telescopic plate, and a gear. The left U-shaped plate and the right U-shaped plate are bilaterally symmetrical structures. Taking the left U-shaped plate as an example to describe its structure, it includes an inclined plate, a vertical plate and two horizontal rods. The inclined plate is located at the top, and the upper end of the vertical plate is connected to the inclined plate at an angle of 110°~130°; the bottom end of the vertical plate is vertically connected to the two horizontal rods, and the two horizontal rods are arranged parallel to the upper and lower sides of the gear, and one of the horizontal rods is provided with serrations; the left U-shaped plate and the right U-shaped plate are symmetrical. The two horizontal rods are staggered and in contact with the gear, wherein the horizontal rod with serrations is engaged with the gear, and the horizontal rod without serrations is located outside the horizontal rod with serrations; the telescopic plate is a hollow movable structure, an elliptical hole is provided inside the telescopic plate, half of the elliptical hole is serrated, the gear is embedded in the telescopic plate and fixed to the bottom plate below by bolts, the gear is respectively engaged with the serrations in the telescopic plate and with the serrations on the horizontal rods of the left U-shaped plate and the right U-shaped plate; that is, the upper, lower and right sides of the gear are respectively engaged with the rack, and stretching the telescopic plate drives the left and right U-shaped plates to move.

[0025] The gear has thickness, and the U-shaped plate is above the telescopic plate. The two are not in the same plane. The upper horizontal rod of the left U-shaped plate is provided with serrations, which meshes with the gear. The lower horizontal rod of the right U-shaped plate is provided with serrations, which meshes with the gear. The lower horizontal rod of the left U-shaped plate is located on the outside of the right U-shaped plate, and the upper horizontal rod of the right U-shaped plate is located on the outside of the left U-shaped plate; the horizontal rod without serrations is slightly shorter. This design makes the U-shaped plate tend to be balanced and stable to prevent lateral twisting.

[0026] The left and right plates of the U-shaped card slot are in an 'embracing' structure, with gears tightly meshing with the serrations on the U-shaped plate, and a plate on top to maintain stability, allowing for flexible placement of particles of different shapes and sizes.

[0027] Furthermore, the support end of the cantilever beam is supported on the microbalance through a U-shaped slot to form an outrigger beam structure; in order to increase the support reaction force caused by the vertical force of the liquid bridge, the support is arranged as close to the end as possible.

[0028] The present invention provides a method for measuring static and dynamic liquid bridges between particles. When measuring the morphology and mechanical properties of liquid bridges between three particles, the method includes the following steps:

[0029] Step 1: Build a static and dynamic measurement system for the liquid bridge between three particles;

[0030] Step 2: Use the height and level adjustment devices to adjust the three particles to the set positions;

[0031] Step 3: Use computer-controlled fine-tuning of the lifting device to bring the upper and lower spherical particles closer together. Use the injection needle of a micro-propellant pump to add a droplet of liquid to the apex of the lower particle's spherical cap. After the needle retracts, lower the upper particle again until the droplets overlap to form a liquid bridge between the three particles. Use a laser rangefinder to record the initial reading of the lower extension beam and the initial reading of the microbalance.

[0032] Step 4: Computer-controlled fine-tuning of the lifting mechanism gradually separates the upper and lower particles, stretching the liquid bridge until it breaks. During this process, a laser rangefinder records the horizontal deflection of the bottom of the extension beam, and a high-speed camera records the entire process of stretching and breaking the liquid bridge.

[0033] Step 5: Calculate the horizontal suction of the liquid bridge indirectly through the horizontal deflection of the extended beam, and read the real-time magnitude of the vertical suction of the liquid bridge through a microbalance; at the same time, apply image processing technology to invert the geometric characteristic parameters of the liquid bridge based on the morphology record.

[0034] The present invention also provides a method for measuring static and dynamic liquid bridges between double ellipsoid particles, comprising the following steps:

[0035] Step 1: Build a static and dynamic measurement system for the liquid bridge between double ellipsoid particles;

[0036] Step 2: Use the height and level adjustment devices to adjust the two ellipsoidal particles to the set position, and use a high-speed camera to align the upper and lower ellipsoidal particles;

[0037] Step 3: Place the lower ellipsoid particle in the second U-shaped slot and secure it to the top of the angle adjustment device's support plate with bolts. Turn the angle adjustment device to rotate the support plate to the set angle. After the beam's self-weight deformation stabilizes, place the U-shaped slot on the first microbalance so that it contacts the bottom of the beam and adjust the balance to zero.

[0038] Step 4: Use computer-controlled fine-tuning of the lifting device to bring the upper and lower ellipsoidal particles closer together. Use the injection needle of a micro-propellant pump to add a droplet of liquid to the apex of the crown of the lower ellipsoidal particle. After the needle is retracted, lower the upper ellipsoidal particle again until the droplet overlaps and forms a liquid bridge between the two ellipsoidal particles. Record the initial reading of the first microbalance at this time.

[0039] Step 5: Computer-controlled fine-tuning of the lifting mechanism gradually separates the upper and lower ellipsoidal particles. A high-speed camera records the geometric morphology of the entire process of liquid bridge stretching and breaking, and a microbalance measures the suction force of the liquid bridge.

[0040] When measuring double ellipsoid particles, only one vibration damping table is required, and the laser rangefinder and second microbalance are removed. The lower ellipsoid particle is clamped in the second U-shaped slot, and the bottom plate of the U-shaped slot is fixedly connected to the support plate of the angle adjustment device below with bolts. By turning the angle adjustment device, the support plate is rotated to the set angle. The liquid bridge suction is read using the microbalance on the vibration damping table. The test steps are basically the same as above. Because the worm gear mechanism is inherently self-locking, the worm gear cannot drive the worm to reverse, so the inclination angle of the support plate can always remain constant during rotation.

[0041] Beneficial effects of the present invention:

[0042] (1) The present invention expands the current two-particle liquid bridge force measurement device to three-particle devices, which can measure the horizontal and vertical components of the liquid bridge suction respectively, providing an experimental idea for conducting more complex particle group suction research.

[0043] (2) Microscopic measurement of the liquid bridge morphology and mechanical properties of ellipsoidal particles at different inclination angles was achieved.

[0044] (3) Through the cantilever beam micro-force measurement technology, the rapidly changing and tiny liquid bridge force measurement is converted into the change of the cantilever beam end deflection, which indirectly realizes the accurate measurement of the liquid bridge force and can clearly record the morphological changes of the liquid bridge during the stretching and fracture process. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structure of the static and dynamic liquid bridge measurement system between three particles of the present invention;

[0046] Figure 2 A partial schematic diagram of a particle placement device of a double-ellipsoid inter-particle liquid bridge measurement system of the present invention;

[0047] Figure 3 Schematic diagram of the electric bevel gear lifting platform of the present invention;

[0048] Figure 4 A partial schematic diagram of a displacement block of the inter-particle static and dynamic liquid bridge measurement system of the present invention;

[0049] Figure 5 It is a partially enlarged front view of the angle adjustment device of the double ellipsoid inter-particle liquid bridge measurement system of the present invention;

[0050] Figure 6 for Figure 5 Right view;

[0051] Figure 7 Schematic diagram of the liquid bridge between three particles of the present invention;

[0052] Figure 8It is a front view of the U-shaped slot of the present invention;

[0053] Figure 9 It is a top view of the U-shaped slot of the present invention.

[0054] In the figure: 1-extension beam, 2-bolt, 3-vibration reduction platform, 4-first U-shaped slot, 5-first microbalance, 6-worm gear, 7-worm, 8-displacement block, 9-lower extension beam, 10-fastening bolt, 11-clamp, 12-upper spherical particle, 13-lower spherical particle, 14-second U-shaped slot, 15-third microbalance, 16-laser rangefinder, 17-electric bevel gear lifting platform, 18-adjustment bracket, 19-high-speed camera, 20-computer, 21-micro propulsion pump, 22-second microbalance, 23-angle adjustment device, 24-upper ellipsoidal particles, 25-lower ellipsoidal particles; 1701-glass tempered plate, 1702-anti-slip pad, 1703-motor, 1704-elevator, 1705-connecting shaft, 1706-screw; 2301-support plate, 2302-worm, 2303-rotating gear, 2304-worm wheel, 2305-outer ring, 2306-angle disk, 2307-packaging shell; 401-gear, 402-right U-shaped plate, 403-telescopic plate, 404-left U-shaped plate. DETAILED DESCRIPTION

[0055] The present invention is further illustrated by the following examples, but is not limited to the following examples.

[0056] like Figures 1 to 9 As shown, a static and dynamic liquid bridge measurement system between particles includes a support module, a displacement adjustment module, a liquid bridge volume control module, a micro-force measurement module, a data acquisition and image processing module, and a particle placement device;

[0057] The support module includes a vibration reduction platform 3 and an L-shaped cantilever beam 1. The vibration reduction platform 3 and the L-shaped cantilever beam 1 are provided in two groups on the left and right with the same structure. One or two groups can be selected for the experiment as needed. An L-shaped cantilever beam is provided above the vibration reduction platform, and the cantilever beam is supported by a microbalance and a first U-shaped slot 4. Figure 1As shown, a first U-shaped slot 4 is provided above the first microbalance 5; a displacement adjustment module is connected to the cantilever beam 1 respectively; the displacement adjustment module includes a horizontal adjustment device and a height adjustment device; the horizontal adjustment device includes a worm gear 6, a worm 7, and a displacement block 8. The worm gear 6 and the worm 7 are connected at the end of the cantilever beam, and the displacement block 8 is connected at the end of the worm 7. The horizontal cantilever beam 1 is connected to the displacement block 8 by the transversely arranged worm 7. By rotating the worm gear, the worm and the displacement block are driven to move horizontally; the height adjustment device includes two sets of devices for coarse adjustment and fine adjustment. The coarse adjustment device includes an adjustment bracket 18, a clip 11, and a lower extension beam 9 with an adjustment accuracy of 5 mm. The lower extension beam 9 is provided at the end of the displacement block 8 of the horizontal adjustment device. The lower extension beam consists of a vertically arranged rectangular plate and a rectangular plate vertically connected to the bottom, and the side is an inverted T-shaped structure; the lower extension beam 9 is fixed to the displacement block 8 by a clip 11 and a fastening bolt 10 (see Figure 4 ), the bottom of the rectangular plate at the bottom of the extended beam is glued to the upper particles; the vertical position of the extended beam and the upper particles is adjusted by loosening the clamp; the adjustment bracket 18 is located at the bottom of the particle placement device, and the vertical position of the lower particles can also be controlled by manually adjusting the bracket; the fine adjustment device includes an electric bevel gear lifting platform 17, which is placed above the adjustment bracket 18; the adjustment accuracy of the fine adjustment device is 0.08mm.

[0058] Specifically, the following dimensions can be used for the downrigger beam 9: a vertically mounted rectangular plate: 150 mm high, 30 mm wide, and 0.1 mm thick; and a vertically connected rectangular plate at the bottom: 5 mm long, 5 mm wide, and 1 mm thick, made of high-flexibility stainless steel. The cross-sectional dimensions should ensure that the downrigger beam exhibits significant horizontal deflection under minimal forces, while not significantly deforming under vertical loads. Particles should preferably be polished soda-lime glass spheres with the physical properties of soil or sand. At the beginning of each test, the particle surface is cleaned with 99% ethanol, and the ethanol is allowed to evaporate completely to prevent mixing with the test liquid.

[0059] The liquid bridge volume control module includes a micro-pump 21 and a syringe needle. The micro-pump 21 is connected to a computer 20 via a controller and can be configured with a lead of 1 mm and a rate ranging from 0.01 mm / min to 150 mm / min. This module is placed behind the particle placement device. The micro-pump controls the syringe needle to add a droplet at the apex of the particle's spherical cap, forming a liquid bridge.

[0060] The particle placement device includes a second U-shaped slot 14, which is located above the electric bevel gear lifting platform 17. The upper particles to be tested are in contact with the downward extension beam; the lower particles to be tested are placed in the second U-shaped slot. The U-shaped slot is used to fix the particles to be tested by adjusting the slot spacing through the telescopic plate.

[0061] The data acquisition and image processing module includes a high-speed camera 19, which records the morphological changes of the interparticle liquid bridge during the entire process of formation, stretching, and breaking through photos and videos. The high-speed camera 19 is mounted on a height-adjustable camera stand with its field of view aligned with the particle group to be tested.

[0062] The micro-force measurement module includes a first microbalance 5 and a second microbalance 22. Each microbalance 5 and 22 are placed on a vibration damping platform 3. A first U-shaped slot 4 is fixed to the weighing pan of each balance. The slot spacing of the first U-shaped slot 4 is adjustable via a telescopic plate to support the cantilever beam. The first and second microbalances have an accuracy of 0.01 mg and a measuring range of 95 g.

[0063] The controller is connected to the computer and can control the operating device after installing the corresponding driver.

[0064] Furthermore, the L-shaped outrigger beam 1 is a horizontal beam, the end of which is bent into an L shape and fixed to a vibration reduction platform 3 by bolts 2. The vibration reduction platform is arranged symmetrically on the left and right.

[0065] Furthermore, one end of the worm 7 of the level adjustment device is sleeved in the cantilever beam 1, and the other end is fixedly connected to the displacement block 8. The worm wheel 6 is fixed to the end of the cantilever beam by bolts.

[0066] Furthermore, the electric bevel gear lifting platform 17 is connected to the computer 20 to achieve precise vertical movement of the lower particles. Specifically, the electric bevel gear lifting platform 17 includes a glass tempered plate 1701, an anti-skid pad 1702, a motor 1703, an elevator 1704, a connecting shaft 1705, and a screw 1706. The glass tempered plate is a rectangular structure plate with four anti-skid pads evenly distributed below it. The bottom of the anti-skid pads is connected to the elevator via a screw. The four elevators are connected by a connecting shaft. The elevators are all connected to the motor and powered by the motor.

[0067] Furthermore, the adjustment bracket 18 is a high-precision small scissor-type lifting workbench, which is used as a part of the coarse adjustment device to adjust the vertical displacement of the sample particles.

[0068] The above-mentioned first U-shaped slot 4 and second U-shaped slot 14 have the same structure; both are composed of a left U-shaped plate 404, a right U-shaped plate 402, a telescopic plate 403, and a gear 401. The left U-shaped plate 404 and the right U-shaped plate 402 are left-right symmetrical structures. Taking the left U-shaped plate 404 as an example to describe its structure, it includes an inclined plate, a vertical plate and two horizontal rods. The inclined plate is located at the top end, and the upper end of the vertical plate is connected to the inclined plate at an angle of 120°. The bottom end of the vertical plate is vertically connected to the two horizontal rods, and the two horizontal rods are arranged parallel to the upper and lower sides of the gear, and one of the horizontal rods is provided with serrations. The two horizontal rods of the left U-shaped plate and the right U-shaped plate are staggered and contact the gear, wherein the horizontal rod with serrations is engaged with the gear, and the horizontal rod without serrations is located outside the horizontal rod with serrations. The telescopic plate 403 is a hollow movable structure with an elliptical hole inside. Half of the ellipse is serrated. A gear is embedded in the telescopic plate and fixed to the bottom plate below by bolts. The gear 401 is respectively engaged with the serrations in the telescopic plate 403 and with the serrations on the horizontal bars of the left U-shaped plate 404 and the right U-shaped plate 402; that is, the upper, lower and right sides of the gear are respectively engaged with the racks of other components, and stretching the telescopic plate drives the left and right U-shaped plates to move.

[0069] like Figure 9 As shown, the gear has thickness, the U-shaped plate is above the telescopic plate, and the two are not in the same plane. The left U-shaped plate has an upper horizontal rod with serrations, which engages with the gear, and the right U-shaped plate has a lower horizontal rod with serrations, which engages with the gear. The lower horizontal rod of the left U-shaped plate is located on the outside of the right U-shaped plate, and the upper horizontal rod of the right U-shaped plate is located on the outside of the left U-shaped plate; the horizontal rod without serrations is slightly shorter. This design makes the U-shaped plate tend to be balanced and stable to prevent lateral twisting.

[0070] The left and right plates of the U-shaped slot are constructed in an "embracing" manner. The gears mesh tightly with the racks on the U-shaped plates, and the upper plate provides stability. This allows for flexible placement of particles of varying shapes and sizes. Furthermore, the gears should have a small meshing gap to ensure a relatively tight fit between the particles and the U-shaped plates, preventing them from moving loose.

[0071] Furthermore, the support end of the cantilever beam 1 is supported on the first or second microbalance through the first U-shaped slot to form an outrigger beam structure; in order to increase the support reaction force caused by the vertical force of the liquid bridge, the support is arranged as close to the end as possible.

[0072] like Figure 1 As shown, one end of the L-shaped cantilever beam 1 is supported on a first microbalance 5 via a first U-shaped slot 4, forming an outrigger structure. To increase the support reaction force caused by the vertical force of the liquid bridge, the balance is placed as close to the end as possible. Because the balance has a very small measuring range, during device construction, after the cantilever beam 1's self-weight deformation stabilizes, the first U-shaped slot 4 is positioned so that it precisely contacts the bottom surface of the beam, minimizing the transmission of the self-weight reaction force to the balance.

[0073] The support reaction force at the microbalance can be calculated according to the force method in structural mechanics. The specific calculation formula is:

[0074] (1)

[0075] Where, , The support reaction force is:

[0076] (2)

[0077] Where, X 1 is the reaction force at the support; F is the vertical force of the liquid bridge; l is the beam length; x is the displacement of the balance support from the beam end; EI is the beam stiffness; δ 11 express X 1 is the unit force acting alone in the basic structure along the support X Displacement in 1 direction; 1p Indicates that the vertical force of the liquid bridge is applied alone in the basic structure along the support X 1 direction displacement. M1 represents the displacement of the basic structure in X Bending moment under 1=1; M p It represents the bending moment of the basic structure under the vertical force of the liquid bridge.

[0078] It can be seen that the closer the balance support is to the fixed end of the L-shaped cantilever beam, the more obvious the amplification effect of the support reaction force.

[0079] The liquid bridge measurement system provided by the present invention can be used to measure static and dynamic liquid bridges between three particles or two ellipsoidal particles. This is described below using specific examples:

[0080] Example 1: Provide a static and dynamic measurement system and method for three-particle liquid

[0081] When three particles are used as the research object, the three-particle test is composed of three spherical particles, the centers of which are located in the same vertical plane, two of which are located at the top and one at the bottom. The particle placement device of the above-mentioned measurement system includes: a second U-shaped slot and a third microbalance; the two upper spherical particles are respectively glued to the bottom of the bottom plate of the two downward extending beams, and the lower spherical particle is placed in the second U-shaped slot. The second U-shaped slot is located above the third microbalance, and the third microbalance is set above the electric bevel gear lifting platform.

[0082] Furthermore, in order to facilitate the adjustment of the two upper particles, the heights of the two lower extension beams are staggered, such as Figure 1As shown, the end of the left outrigger beam is lower than that of the right end. This is because the particles are very close together. This is to facilitate installation and to prevent the left and right vibration damping platforms from contacting each other and hindering particle movement.

[0083] A laser rangefinder is also provided on the side of the three-particle placement device; the laser rangefinder is arranged on the left and right sides of the downward extending beam, and the laser light spot is aligned with the midpoint of the bottom end of the downward extending beam.

[0084] use Figure 1 The provided three-particle liquid static and dynamic measurement system has the following test steps:

[0085] Step 1: Build a three-particle liquid static and dynamic measurement system;

[0086] Step 2: Use the height and level adjustment devices to adjust the three particles to the set positions;

[0087] Step 3: Computer 20 controls the fine-tuning lifting device 17 to gradually bring the upper and lower spherical particles closer together. A droplet of liquid is added to the apex of the cap of the lower spherical particle 13 via a micro-pump 21. After the needle retracts, the upper spherical particle 12 is lowered until the droplet forms a liquid bridge between the three particles. The initial readings of the lower extension beam 9 and the microbalance are recorded using a laser rangefinder 16.

[0088] Step 4: Computer 20 controls the fine-tuning lifting device 17 to move the upper spherical particle 12 away from the lower spherical particle 13. The lower spherical particle 13 is fixed in the second U-shaped slot 14. The particle is slowly raised in the vertical direction in steps of 0.02 mm. After the balance reading stabilizes, the micro-force (the vertical component of the suction force) is read and the corresponding displacement is recorded until the liquid bridge breaks. The deflection of the lower extension beam 9 is recorded by a laser rangefinder 16, and the high-speed camera 19 records the morphological changes of the entire liquid bridge stretching and breaking process.

[0089] Step 5: Calculate the horizontal suction of the liquid bridge indirectly through the horizontal deflection of the downward extension beam 9, and read the real-time magnitude of the vertical suction of the liquid bridge through a microbalance; record the entire process of formation, stretching, and fracture of the liquid bridge between the two balls through a high-speed camera 19, and apply image processing technology to obtain the geometric parameters of the liquid bridge morphology.

[0090] Example 2: Provide a static and dynamic measurement system and method for double ellipsoidal particles in liquid

[0091] When using a double ellipsoid as the research object, the double ellipsoid test particle consists of an upper and a lower ellipsoidal particle, with the centers of the two ellipsoids located on the same vertical line. The particle placement device of the above-mentioned measurement system includes a second U-shaped slot and an angle adjustment device. The upper ellipsoidal particle is cemented to the bottom end of the downward extending beam, and the lower ellipsoidal particle is clamped into the second U-shaped slot. The angle adjustment device is provided below the second U-shaped slot.

[0092] When measuring bi-ellipsoidal particles, only one vibration damping platform 3 is required, while the laser rangefinder 16 and second microbalance 15 are removed. The lower particle is clamped into the U-shaped slot 14 and bolted to the support plate of the angle adjustment device 23. By turning the angle adjustment device 23, the support plate is rotated to the set angle. The liquid bridge suction is measured using the first microbalance 5 on the vibration damping platform 3. The test steps are essentially the same as above.

[0093] The angle adjustment device 23 includes a support plate 2301, a worm 2302, a worm wheel 2304, a rotating gear 2303, an outer ring 2305, an angle disc 2306, and an enclosure 2307. The support plate 2301 is a square steel plate used to hold the particles, with a worm gear mechanism located at the bottom. The outer ring 2305 fits over the outer edge of the rotating gear 2303 and is bolted to the bottom of the support plate 2301 to form a gear housing, which ensures that the worm wheel 2304 and the rotating gear 2303 maintain close contact at all times. The worm wheel 2304 is located above the rotating gear 2303 and is tightly meshed with it. The rotating worm 2302 drives the worm wheel 2304 to rotate, thereby causing the support plate 2301 to rotate along the outer edge of the gear. The surfaces of the worm gear mechanism and the enclosure 2307 of the rotating gear 2303 below are respectively provided with a pointer and an angle disc 2306 to indicate the tilt angle of the particles. Since the worm gear mechanism itself has a self-locking property, the worm wheel 2304 cannot drive the worm 2302 to reverse, so that the inclination angle of the support plate 2301 can always remain constant during the rotation process.

[0094] The method for measuring static and dynamic liquid bridges between double ellipsoid particles includes the following steps:

[0095] Step 1: Build a static and dynamic measurement system for the liquid bridge between double ellipsoid particles;

[0096] Step 2: The two ellipsoid particles are adjusted to the set positions by the height and level adjustment devices, and the upper and lower ellipsoid particles are aligned by the high-speed camera 19;

[0097] Step 3: Place the lower ellipsoid particle 25 on the second U-shaped slot 14 and secure it to the top of the angle adjustment device 23 with bolts. Turn the angle adjustment device to rotate the plate to the set angle. After the beam's self-weight deformation stabilizes, place the first U-shaped slot on the first microbalance so that it contacts the bottom of the beam and adjust the balance to zero.

[0098] Step 4: The computer 20 controls the fine adjustment of the lifting device to bring the upper and lower ellipsoidal particles closer together. The injection needle of the micro-propellant pump 21 is used to add a droplet of liquid to the apex of the crown of the lower ellipsoidal particle 25. After the needle is retracted, the upper ellipsoidal particle 24 is lowered again until the droplet overlaps the two ellipsoidal particles to form a liquid bridge. The initial reading of the first microbalance 5 at this time is recorded.

[0099] Step 5: The computer 20 controls the fine adjustment of the lifting device to gradually separate the upper and lower ellipsoidal particles. The high-speed camera 19 records the geometric morphology of the entire process of liquid bridge stretching and breaking; and the first microbalance 5 reads the magnitude of the liquid bridge suction.

[0100] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A system for measuring static and dynamic liquid bridges between particles, characterized by: It includes a support module, a displacement adjustment module, a liquid bridge volume control module, a micro-force measurement module, a data acquisition and image processing module, and a particle placement device; The support module includes a vibration reduction platform and an L-shaped cantilever beam, which are provided in two groups on the left and right and have the same structure. The L-shaped cantilever beam is provided above the vibration reduction platform, and the cantilever beam is supported by a microbalance and a first U-shaped slot, and the displacement adjustment modules are respectively connected to the cantilever beam. The displacement adjustment module includes a horizontal adjustment device and a height adjustment device; the horizontal adjustment device includes a worm gear, a worm, and a displacement block. The worm gear and the worm are connected at the end of the cantilever beam, and the displacement block is connected at the end of the worm gear. The horizontal cantilever beam is connected to the displacement block through a transversely arranged worm gear. By rotating the worm gear, the worm gear and the displacement block are driven to move horizontally; the height adjustment device includes two sets of devices, a coarse adjustment device and a fine adjustment device. The coarse adjustment device includes an adjustment bracket, a clip, and a lower extension beam. The lower extension beam is arranged at the end of the displacement block of the horizontal adjustment device. The lower extension beam is composed of a vertically arranged rectangular parallelepiped The device is composed of a rectangular plate vertically connected to the bottom and a side in an inverted T-shaped structure; the adjustment bracket is located at the bottom of the particle placement device, and the vertical position of the lower particle can be controlled by manually adjusting the bracket; the fine adjustment device includes an electric bevel gear lifting platform, which is placed above the adjustment bracket; the lower extension beam of the coarse adjustment device is fixed to the displacement block by a clamp, and the bottom of the rectangular plate at the bottom of the lower extension beam is cemented to the sample particle; the vertical position of the lower extension beam and the upper particle is adjusted by loosening the clamp; the adjustment accuracy of the coarse adjustment device is 5mm, and the adjustment accuracy of the fine adjustment device is 0.08mm; The liquid bridge volume control module includes a micro-propulsion pump and an injection needle. The micro-propulsion pump is connected to a computer through a controller. The module is placed behind the particle placement device. The micro-propulsion pump controls the injection needle to add a droplet at the apex of the particle cap to form a liquid bridge. The particle placement device includes a second U-shaped slot located above the electric bevel gear lifting platform, wherein the upper particles to be tested are in contact with the downward extension beam; the lower particles to be tested are placed in the second U-shaped slot, and the second U-shaped slot is used to fix the particles to be tested by adjusting the slot spacing through the telescopic plate; The data acquisition and image processing module includes a high-speed camera, which records the morphological changes of the interparticle liquid bridge during the entire process of formation, stretching and breaking through photos and videos; The micro-force measurement module includes a first microbalance and a second microbalance; wherein, the first microbalance and the second microbalance are placed on a vibration reduction table, and a first U-shaped slot is fixed on the balance weighing plate. The U-shaped slot is used to adjust the slot spacing through a telescopic plate to support the cantilever beam.

2. The inter-particle static and dynamic liquid bridge measurement system according to claim 1, characterized in that: The L-shaped outrigger beam is a horizontal beam with its end bent into an L shape and fixed to the vibration reduction platform by bolts. The vibration reduction platform is arranged symmetrically on the left and right. One end of the worm of the level adjustment device is sleeved in the cantilever beam, and the other end is fixedly connected to the displacement block; the worm wheel is fixed to the end of the cantilever beam by bolts.

3. The inter-particle static and dynamic liquid bridge measurement system according to claim 1, characterized in that: The electric bevel gear lifting platform is connected to a computer to achieve precise vertical movement of the lower particles; the electric bevel gear lifting platform includes a glass tempered plate, an anti-slip pad, a motor, an elevator, a connecting shaft and a screw; the glass tempered plate is a rectangular structural plate, and four anti-slip pads are evenly distributed underneath it. The bottom of the anti-slip pad is connected to the elevator through a screw, and the four elevators are connected by a connecting shaft. The elevators are all connected to the motor and powered by the motor.

4. The inter-particle static and dynamic liquid bridge measurement system according to claim 1, characterized in that: The adjustment bracket is a high-precision small scissor-type lifting workbench; the high-speed camera is installed on the height-adjustable camera bracket, and the field of view is aligned with the particle group to be tested.

5. The inter-particle static and dynamic liquid bridge measurement system according to claim 1, characterized in that: When the particle to be tested is a three-sphere particle, the centers of the three spheres are located in the same vertical plane, two of which are located at the top and one at the bottom; The particle placement device also includes a third microbalance; two upper spherical particles are respectively bonded to the bottom of the bottom plates of the two downward extending beams, and the lower spherical particle is placed in a second U-shaped slot, which is located above the third microbalance, which is arranged above the electric bevel gear lifting platform; to facilitate adjustment of the two upper particles, the heights of the two downward extending beams are staggered; A laser rangefinder is also provided on the side of the particle placement device; the laser rangefinder is arranged on the left and right sides of the downward extending beam, and the laser light spot is aligned with the midpoint of the bottom end of the downward extending beam.

6. The inter-particle static and dynamic liquid bridge measurement system according to claim 1, characterized in that: When the particle to be tested is a double ellipsoid particle, the double ellipsoid particle is composed of an upper ellipsoidal particle and a lower ellipsoidal particle, and the centers of the two ellipsoids are located on the same vertical line; The particle placement device also includes an angle adjustment device, the upper ellipsoid particle is fixed under the bottom plate of the lower extension beam, and the lower ellipsoid particle is fixed in the second U-shaped slot, and an angle adjustment device is provided under the second U-shaped slot; the angle adjustment device includes a worm gear mechanism, a rotating gear, an angle disk, a support plate, an outer ring, and an encapsulation shell; the support plate is a steel square plate for placing particles, and a worm gear mechanism is provided at the bottom; the outer ring is sleeved on the outer edge of the rotating gear and is connected to the bottom of the support plate by bolts to form a whole, so as to keep the worm gear and the gear in close contact at all times; the worm gear is located above the rotating gear and is tightly engaged with it, and the worm gear is driven to rotate by rotating the worm, thereby causing the support plate to rotate along the outer edge of the gear; the worm gear mechanism and the surface of the encapsulation shell of the rotating gear below are respectively provided with pointers and angle scales for indicating the inclination angle of the lower particle.

7. The inter-particle static and dynamic liquid bridge measurement system according to claim 1, characterized in that: The structures of the first U-shaped slot and the second U-shaped slot are the same; both are composed of a left U-shaped plate, a right U-shaped plate, a telescopic plate, and a gear. The left U-shaped plate and the right U-shaped plate are left-right symmetrical structures. The left U-shaped plate includes an inclined plate, a vertical plate and two horizontal rods. The inclined plate is located at the top, and the upper end of the vertical plate is connected to the inclined plate at an angle of 110°~130°; the bottom end of the vertical plate is vertically connected to the two horizontal rods, and the two horizontal rods are arranged parallel to the upper and lower sides of the gear, and one of the horizontal rods is provided with serrations; the two horizontal rods of the left U-shaped plate and the right U-shaped plate are staggered and contacted with the gear, wherein the horizontal rod with serrations meshes with the gear, and the horizontal rod without serrations is located outside the horizontal rod with serrations; the telescopic plate is a hollow movable structure, and an elliptical hole is provided inside the telescopic plate, half of the ellipse is serrated, and the gear is embedded in the telescopic plate and fixed to the bottom plate below by bolts, and the gears mesh with the serrations in the telescopic plate and with the serrations on the horizontal rods of the left U-shaped plate and the right U-shaped plate respectively.

8. A method for measuring static and dynamic liquid bridges between particles using the system for measuring static and dynamic liquid bridges between particles according to any one of claims 1 to 5 or 7, characterized in that The following steps are involved: Step 1: Build a static and dynamic measurement system for the liquid bridge between three particles; Step 2: Use the height and level adjustment devices to adjust the three particles to the set positions; Step 3: Use computer-controlled fine-tuning of the lifting device to bring the upper and lower spherical particles closer together. Use the injection needle of a micro-propellant pump to add a droplet of liquid to the apex of the lower particle's spherical cap. After the needle retracts, lower the upper particle again until the droplets overlap to form a liquid bridge between the three particles. Use a laser rangefinder to record the initial reading of the lower extension beam and the initial reading of the microbalance. Step 4: The upper and lower particles are gradually separated by fine-tuning the lifting device controlled by a computer, stretching the liquid bridge until it breaks. During this process, a laser rangefinder records the horizontal deflection of the bottom of the extension beam, and a high-speed camera records the morphology of the entire process of liquid bridge stretching and breaking. Step 5: Calculate the horizontal suction of the liquid bridge indirectly through the horizontal deflection of the extended beam, and read the real-time magnitude of the vertical suction of the liquid bridge through a microbalance; at the same time, apply image processing technology to invert the geometric characteristic parameters of the liquid bridge based on the morphology record.

9. A method for measuring static and dynamic liquid bridges between particles using the system for measuring static and dynamic liquid bridges between particles according to any one of claims 1 to 4 or 6 to 7, characterized in that The following steps are involved: Step 1: Build a static and dynamic measurement system for the liquid bridge between double ellipsoid particles; Step 2: Use the height and level adjustment devices to adjust the two ellipsoidal particles to the set position, and use a high-speed camera to align the upper and lower ellipsoidal particles; Step 3: The lower ellipsoid particle is clamped on the second U-shaped slot and fixed above the support plate of the angle adjustment device by bolts; the angle adjustment device is turned to rotate the support plate to the set angle. After the deformation of the beam due to its own weight is stable, the U-shaped slot is placed above the first microbalance so that it is in contact with the bottom surface of the beam, and the balance is adjusted to zero at the same time; Step 4: Use computer-controlled fine-tuning of the lifting device to bring the upper and lower ellipsoidal particles closer together. Use the injection needle of a micro-propellant pump to add a droplet of liquid to the apex of the crown of the lower ellipsoidal particle. After the needle is retracted, lower the upper ellipsoidal particle again until the droplet overlaps and forms a liquid bridge between the two ellipsoidal particles. Record the initial reading of the first microbalance at this time. Step 5: The upper and lower ellipsoid particles are gradually separated by fine-tuning the lifting device controlled by a computer; the geometric morphology of the entire process of liquid bridge stretching and breaking is recorded with a high-speed camera; and the magnitude of the liquid bridge suction is read by the first microbalance.

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