CN111735677A - Testing equipment and testing method for shear stress of solid particle material - Google Patents
Testing equipment and testing method for shear stress of solid particle material Download PDFInfo
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- CN111735677A CN111735677A CN202010581692.9A CN202010581692A CN111735677A CN 111735677 A CN111735677 A CN 111735677A CN 202010581692 A CN202010581692 A CN 202010581692A CN 111735677 A CN111735677 A CN 111735677A
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- telescopic cylinder
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/04—Chucks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
Abstract
The invention provides a test device and a test method for shear stress of a solid particle material, wherein the test device comprises: a load tray (30); a plurality of sub-moulds (10), each sub-mould (10) and the load tray (30) enclosing an internal cavity for compaction moulding of the solid particulate material; the opening and closing device is connected outside each split mold (10) and respectively controls the opening and closing of each split mold (10); and the compacting device is positioned above the inner cavity, wherein the compacting device comprises a telescopic rod (70) and a compacting piece (50) which are sequentially connected from top to bottom, and the telescopic rod (70) can drive the compacting piece (50) to compact the solid particle materials positioned in the inner cavity. According to the invention, the plurality of split molds surround the sample preparation inner cavity, after sample preparation is completed, the split molds are separated, and then a shearing test is carried out, so that the influence of the friction force of the inner wall of the mold on the test result in the prior art is avoided, and the test result is more accurate.
Description
Technical Field
The invention relates to the technical field of rock-soil mechanical tests, in particular to a test device and a test method for shear stress of a solid particle material.
Background
The increase in the inherent moisture of the solid particulate material leads to an increase in its internal shear stress and a deterioration in the flow properties. This can lead to reduced flow in various storage and handling equipment, to parts of the particulate material adhering to the walls of the container, or to unstable material flow due to moisture content. Therefore, there is a need to guide the design and optimization of on-site storage and handling equipment by measuring the shear stress response of a particular solid particulate material under a variety of moisture and principal stress conditions.
The flow course of a solid particulate material is determined by the shear stress at its particular principal stress, the flow function of which is its unconstrained yield strength σcAnd principal stress sigma1The relationship between them. Among the various test methods for measuring shear stress, the direct shear test is widely accepted and used. Fig. 15 is a graph showing the relationship between unconfined yield stress and principal stress obtained using a direct shear test. However, the direct shear test has several disadvantages: in order to obtain reliable and repeatable results, experienced operators will perform pre-consolidation, pre-shearing and shearing processes from which the shear stress at a specific principal stress is obtained, thereby deriving a flow function for the tested material, a method that is highly skilled for the operator; furthermore, direct shear testing is very time consuming, often requiring several days to complete a material test; direct shear testing is also not suitable for on-site performance and must be performed in a laboratory environment to obtain accurate results. Furthermore, the testing process may produce measurement errors because the direct shear test must be performed on multiple samples.
An alternative method of testing the shear stress of solid particulate materials is to perform uniaxial compression tests. FIG. 16 is a schematic illustration of a uniaxial compression test. As shown in fig. 16, at a predetermined consolidation pressure σ1Then, the sample material is injected into a cylindrical mold at one time and compacted to form a sample, then the load corresponding to the consolidation stress is removed, the mold is opened, and an unconstrained freely consolidated cylindrical sample is leftAnd then a compression test is performed. Fig. 13 is a graph comparing the unconfined yield stress and principal stress obtained from the direct shear test and the uniaxial compression test, and referring to fig. 13, the uniaxial compression test is simple to operate, but the test results are not as accurate as the direct shear test. When a specific main consolidation stress sigma is applied1In time, due to the friction force of the inner wall of the mold, a corresponding Janssen effect (granary effect) is generated to promote the main consolidation stress sigma1Decays exponentially with sample depth. In uniaxial compression tests, mathematical methods have been developed to correct the relationship between unconstrained yield stress and principal stress, but the correction coefficient often varies with the type of material and cannot be generally applied.
Another method is a sample preparation method using a traditional dynamic triaxial test, which is to wrap a film around a sample and add lubricating oil between the film and the mold wall to minimize the wall friction effect. In addition, further attempts were made to eliminate the wall friction effect using a multilayer sample preparation method. The latter two attempts may allow the results between unconstrained yield stress and principal stress to approach the results of the direct shear test indefinitely. However, the testing procedures for both of these methods are complex and inefficient for commercial or industrial use.
Disclosure of Invention
On one hand, the invention aims to solve the problem of providing the test equipment for the shear stress of the solid particle material, the test equipment can eliminate the influence of the friction force of the inner wall of the die, the test process is quick, and the test result is accurate.
The technical problem to be solved by the invention is to provide a method for testing the shear stress of the solid particle material, the method can eliminate the influence of the friction force of the inner wall of the die, the testing process is rapid, and the testing result is accurate.
In order to achieve the above object, an aspect of the present invention provides a test apparatus for shear stress of a solid particulate material, the test apparatus comprising: the device comprises a load plate, a plurality of split molds, an opening and closing device and a compacting device, wherein each split mold and the load plate enclose an inner cavity which takes the load plate as a bottom and the split molds as side walls and is used for compacting and forming the solid particle materials, the opening and closing device is connected outside each split mold and respectively controls the opening and closing of each split mold, and the split molds are positioned above the inner cavity, wherein the compacting device comprises a telescopic rod and a compacting piece which are sequentially connected from top to bottom, and the telescopic rod can drive the compacting piece to compact the solid particle materials in the inner cavity.
Preferably, the load tray is connected to the chassis of the test device by a swivelling lever.
Further preferably, a handle is connected to the rotating rod.
Preferably, a discharge hopper is obliquely arranged below the load tray.
Further, the test equipment further comprises a mould platform, and the opening and closing device takes the mould platform as a support.
Furthermore, the opening and closing device comprises a first telescopic cylinder connected to the mold platform, and the first telescopic cylinder is hinged to the outer wall of the mold splitting device.
Furthermore, the opening and closing device further comprises a baffle and a connecting rod mechanism, the connecting rod mechanism comprises a first connecting rod and a second connecting rod, one end of the first connecting rod is hinged to the end of the piston rod of the first telescopic cylinder, the other end of the first connecting rod is hinged to the outer wall of the die, one end of the second connecting rod is hinged to the outer wall of the die, the other end of the second connecting rod is hinged to the baffle, and the first telescopic cylinder can drive the baffle to move along with the die to shield the die.
Further, the opening and closing device comprises a baffle which can be slidably arranged on the die platform, a second telescopic cylinder and a fixed end which are fixed at the bottom of the die platform, and a first telescopic cylinder which is arranged on the baffle, wherein the telescopic end of the second telescopic cylinder is fixedly connected with the baffle, the telescopic end of the first telescopic cylinder is connected with the die and the baffle through a connecting rod mechanism, the connecting rod mechanism comprises a first connecting rod, one end of which is hinged to the telescopic end of the first telescopic cylinder, and the other end of which is hinged to the first connecting rod on the outer wall of the die, and a second connecting rod, the other end of which is hinged to the second connecting rod on the baffle, and the first telescopic cylinder and the second telescopic cylinder can drive the die to move along with the baffle so that the baffle can shield the die.
Preferably, the die platform is provided with a limit groove of the baffle.
Preferably, a load sensor is connected between the telescopic rod and the compacting member, the telescopic rod can drive the compacting member to apply a shearing force to the compacted solid particulate material, and the load sensor measures the shearing force.
In a second aspect, the present invention provides a method for testing shear stress of a solid particulate material, the method comprising the steps of:
1) starting the opening and closing device, closing each split mold to form an inner cavity formed by compacting the solid granular material together with the load plate;
2) adding the solid particulate material to the internal cavity and compacting;
3) repeating step 2) a plurality of times until the inner cavity is filled with the compacted solid particulate material;
4) and starting the opening and closing device, separating the split dies, applying a shearing force to the split dies from the upper part of the material, and measuring the shearing force.
Through the technical scheme, the invention has the following beneficial effects:
1. according to the invention, the plurality of split molds surround the sample preparation inner cavity, after sample preparation is completed, the split molds are separated, and then a shearing test is carried out, so that the influence of the friction force of the inner wall of the mold on the test result in the prior art is avoided, and the test result is more accurate; the sample preparation and the test are carried out on the test equipment, the test flow is shortened, the test efficiency is high, the unexpected factor caused by overlong flow is avoided, and the test equipment can be popularized and used; the solid particle material can be fed in batches, the next feeding is carried out after each feeding and compaction, the porosity of the solid particle material is close to that of a direct shearing sample, the test result is also very close, the solid particle material is kept along with the depth, and the measurement accuracy is high.
2. In the preferred embodiment of the invention, the load disk can be rotatably arranged, and can rotate during sample preparation, so that the further compaction state lifting of the sample can be realized, and the accuracy of the subsequent test result can be ensured.
3. In the preferred embodiment of the invention, part or all of the opening and closing devices comprise the baffle, and the baffle can not only provide extra support for the whole structure, so that the inner cavity structure is more stable when a sample to be tested is manufactured, but also can prevent materials from splashing, and effectively protect the safety of operators.
4. In the preferred embodiment of the invention, the load sensor is connected between the telescopic rod and the compacting member, and after sample preparation is finished, a shear test can be directly carried out on a sample, so that the test flow is greatly shortened.
Drawings
FIG. 1 is a schematic block diagram of one embodiment of a test apparatus of the present invention;
FIG. 2 is a rear view of the test apparatus of the present invention;
FIG. 3 is a side view of the test apparatus of the present invention;
FIG. 4 is a top view of the test apparatus of the present invention;
FIG. 5 is a schematic view of FIG. 3 looking from A;
FIG. 6 is a right side view of FIG. 5;
FIG. 7 is a rear view of FIG. 5;
fig. 8 is a perspective view of fig. 5 from the rear;
FIG. 9 is a schematic view of the connection of the chassis to the stand in the present invention;
FIG. 10 is a right side view of FIG. 9;
FIG. 11 is a bottom view of FIG. 9;
FIG. 12 is a perspective view of FIG. 9;
FIG. 13 is a graph comparing the unconfined yield stress versus principal stress obtained from a direct shear tester and uniaxial compression test and in accordance with the present invention;
FIG. 14 is a graph comparing the compressive stress and porosity generated by a direct shear tester, a uniaxial compression test tester, and the present invention on a test specimen;
FIG. 15 is a schematic representation of the shear stress of a prior art specimen obtained using a direct shear tester, and the corresponding unconstrained yield stress versus principal stress;
FIG. 16 is a schematic view of a prior art uniaxial compression test procedure.
Description of the reference numerals
10-division mold 11 chassis
12 mould platform 20 first telescopic cylinder
21 second telescopic cylinder 30 load disc
31 rotating rod 40 load sensor
50 compression 60 support
70 telescopic rod 80 handle
100 baffle of 90 discharge hopper
101 first connecting rod 102 second connecting rod
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
It should be noted that, in the following description, for clarity of explanation of the technical solution of the present invention, some orientation words, such as "up", "down", etc., are used according to the orientation that the testing device of the present invention normally refers to in the use state, and "inside", "outside", etc., are used according to the orientation that the components of the testing device normally refers to, for example, the inner cavity is inside, and the opposite portion is outside. This is done solely for the purpose of facilitating the description of the invention and simplifying the description, and is not intended to indicate or imply that the device or element so referred to must be in a particular orientation, constructed and operated, and therefore should not be taken as limiting the invention.
Furthermore, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, and therefore the features defined "first", "second" may explicitly or implicitly include one or more of the features described.
In the description of the present invention, it should be noted that, unless otherwise explicitly stated or limited, the terms "mounted" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; either directly or indirectly through intervening media, either internally or in any combination thereof. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Referring to fig. 1 to 12, as one embodiment of the present invention, a test apparatus for shear stress of a solid particulate material according to the present invention includes: the device comprises a load plate 30, a plurality of sub-dies 10, an opening and closing device and a compacting device, wherein each sub-die 10 and the load plate 30 enclose an inner cavity which takes the load plate 30 as a bottom and the sub-dies 10 as side walls and is used for compacting and forming the solid granular materials, the opening and closing device is connected outside each sub-die 10 and respectively controls the opening and closing of each sub-die 10, the compacting device is positioned above the inner cavity, the compacting device comprises an expansion rod 70 and a compacting piece 50 which are sequentially connected from top to bottom, and the expansion rod 70 can drive the compacting piece 50 to compact the solid granular materials positioned in the inner cavity. The compacting device is attached to the chassis 11 of the test apparatus by means of a bracket 60 so that it is located above the cavity, i.e. the upper end of the telescopic rod 70 is attached to the bracket 60.
The number of the split dies 10 is at least two, preferably 3, and the 3 split dies 10 form an inner cavity, so that the structure is more stable. When the device is used, each opening and closing device drives each sub-die 10 to surround and form an inner cavity with the load plate 30, the force is continuously applied to the sub-die 10, solid particle materials are added into the inner cavity, the telescopic rod 70 drives the compaction piece 50 to compact the materials, then each opening and closing device drives each sub-die 10 to separate, namely, the compacted solid particle materials to be tested are separated, then shearing force is applied to the materials, and the test result is read. Each sub-mold 10 is separated from the compacted material to be tested, so that the influence of the friction force of the inner wall of the mold on the test result in the prior art is avoided, and the test result is more accurate. And in the second aspect, sample preparation and test are carried out on the test equipment, so that the test flow is shortened, unexpected factors caused by overlong flow are avoided, and the labor intensity is reduced. In a third aspect, the solid particulate material may be fed in batches, each charge being compacted and then fed next as shown in figure 14, with a porosity close to that of the direct shear sample, as shown in figure 13, with test results very close to that of the direct shear, and with a maintained depth, with a high degree of accuracy.
In one embodiment of the present invention, the load tray 30 is connected to the chassis 11 of the testing apparatus via a rotating rod 31, for example, a hole may be formed in the chassis 11 and a bearing may be disposed in the hole, and the rotating rod 31 is fixedly disposed on an inner ring of the bearing. When the sample is prepared, the load disc 30 is driven to rotate by rotating the rotating rod 31, so that the further compaction state of the sample is promoted, and the accuracy of a subsequent test result is ensured. For convenience of operation, a rotation handle 80 may be connected to the rotation rod 31 to facilitate application of force.
In the shearing test process, the sample to be tested is broken and dropped due to the shearing force, and in order to avoid splashing of the dropped fragments, the discharge hopper 90 which is obliquely arranged is arranged below the load disk 30, so that the fragments are guided by the discharge hopper 90 and then fall to the same position for collection. A collection hopper may be placed at the inclined bottom of the discharge hopper 90 to collect the pieces. The discharge hopper 90 may be secured to the bottom of the support frame 60 or the mold platform 12.
Further, the test equipment further comprises a mould platform 12, and the opening and closing device takes the mould platform 12 as a support.
The following are some embodiments of the opening and closing device of the present invention.
Firstly, the opening and closing device comprises a first telescopic cylinder 20 connected to the mold platform 12, and the first telescopic cylinder 20 is hinged to the outer wall of the split mold 10.
When there are 2 branch moulds 10, each first telescoping cylinder 20 all is perpendicular to the outer wall of the branch mould 10 of respective control for its axle center of pointing to the inner chamber, inner chamber structure is more stable like this.
When there are 3 split dies 10, as shown in fig. 1, 4, 5 and 8, one of the first telescopic cylinders 20 may be arranged perpendicular to the split dies 10 controlled by it, and the other two first telescopic cylinders 20 may be arranged oblique to the split dies 10 controlled by them, and when each split die 10 is opened, the two first telescopic cylinders 20 bring the split dies 10 controlled by them to both sides of the inner cavity. In addition, the cavity structure formed by the 3 split molds 10 is more stable.
In order to further ensure the stability and safety of the structure, the opening and closing device further comprises a baffle 100 and a connecting rod mechanism, the connecting rod mechanism comprises a first connecting rod 101 and a second connecting rod 102, wherein one end of the first connecting rod is hinged to the end of the piston rod of the first telescopic cylinder 20, the other end of the first connecting rod is hinged to the outer wall of the split mold 10, one end of the second connecting rod 102 is hinged to the outer wall of the split mold 10, and the other end of the second connecting rod 102 is hinged to the baffle 100, and the first telescopic cylinder 20 can drive the baffle 100 to move along with the split mold 10 so as to shield the. When each partial mould 10 surrounds, each baffle 100 also leans on each other, gives whole structure extra support for when the preparation sample that awaits measuring, inner chamber structure is more stable. In addition, the baffle 100 can also prevent materials from splashing, and effectively protect operators.
Secondly, as shown in fig. 6 to 8, the opening and closing device includes a baffle 100 slidably disposed on the mold platform 12, a second telescopic cylinder 21 fixed at the bottom of the mold platform 12, and a first telescopic cylinder 20 fixed at the baffle 100, the telescopic end of the second telescopic cylinder 21 is fixedly connected with the baffle 100, the telescopic end of the first telescopic cylinder 20, the die 10 and the baffle 100 are connected through a connecting rod mechanism, the connecting rod mechanism comprises a first connecting rod 101 with one end hinged on the telescopic end of the first telescopic cylinder 20 and the other end hinged on the outer wall of the split die 10 and a second connecting rod 102 with one end hinged on the outer wall of the split die 10 and the other end hinged on the baffle 100, the first telescopic cylinder 20 and the second telescopic cylinder 21 can drive the split mold 10 to move along with the baffle 100 so that the baffle 100 shields the split mold 10. When the split dies 10 are surrounded, the second telescopic cylinder 21 extends to drive the baffle 100 to move, the first telescopic cylinder 20 also extends, the movable baffle 100 and the extended first telescopic cylinder 20 drive the split dies 10 to surround together, and the split dies 10 are separated when the first telescopic cylinder 20 and the second telescopic cylinder 21 are shortened. Compared with the first embodiment, the first telescopic cylinder 20 and the second telescopic cylinder 21 of the embodiment move more stably, and the structure of the inner cavity formed by the surrounding of the split dies 10 is more stable.
Preferably, the mold platform 12 is provided with a limit groove of the baffle 100, and the baffle 100 moves along the limit groove, so that the split mold 10 can reach a specific position along a specific track when being surrounded and separated, thereby ensuring stable and fixed structure, good test repeatability and high accuracy.
On the basis of the technical scheme, in order to further simplify the test flow, a load sensor 40 is connected between the telescopic rod 70 and the compaction piece 50, after the material to be tested is compacted, the sub-dies 10 are separated, the telescopic rod 70 drives the compaction piece 50 to apply a shearing force to the material to be tested, and the shearing force is measured by the load sensor 40.
The test equipment further comprises a control system, wherein the control system is preferably arranged on the support 60 and used for controlling the action and the action degree of each telescopic cylinder and each telescopic rod so as to improve the automation capacity of the test equipment and avoid the test error caused by manual operation.
The invention also provides a method for testing the shear stress of the solid particle material, which comprises the following steps:
1) starting the opening and closing device, closing each sub-mold 10 to form an inner cavity formed by compacting the solid granular material together with the load plate 30;
2) adding the solid particulate material to the internal cavity and compacting;
3) repeating step 2) a plurality of times until the inner cavity is filled with the compacted solid particulate material;
4) starting the opening and closing device, separating the split dies 10, applying a shearing force to the split dies from the upper side of the material, and measuring the shearing force.
The test method can avoid the influence of the inner wall of the mold on the measurement result, and sample preparation and measurement are realized on the test equipment, thereby greatly shortening the test flow.
The following is a preferred embodiment of the present invention.
As shown in fig. 1 to 12, the apparatus for testing shear stress of solid particulate material includes a load plate 30, a compacting device, 3 split molds 10, and opening and closing devices corresponding to the split molds 10, each split mold 10 and the load plate 30 enclosing an inner cavity formed by compacting the solid particulate material with the load plate 30 as a bottom and the split mold 10 as a side wall, the opening and closing devices being connected to the outside of each split mold 10 and respectively controlling the opening and closing of each split mold, the compacting device being located above the inner cavity, the compacting device including an expansion link 70 and a compacting member 50 connected in sequence from top to bottom, and the compacting device being connected to a chassis 11 of the apparatus through a bracket 60 so as to be located above the inner cavity. A load cell 40 is also provided between the extension rod 70 and the compacting member 50. The load tray 30 is attached to the chassis 11 of the test apparatus by means of a rotatable lever 31, and a rotation handle 80 is attached to the rotatable lever 31. The bracket 60 is provided with a discharge hopper 90 positioned below the load tray 30 and disposed at an incline. One of the opening and closing devices is a first telescopic cylinder 20 vertical to the split dies 10, the cylinder body of the first telescopic cylinder is fixed on a support 60, the other two opening and closing devices are arranged obliquely to the split dies 10 controlled by the opening and closing devices and respectively comprise a baffle 100 which can be arranged on the die platform 12 in a sliding manner, a second telescopic cylinder 21 fixed at the bottom of the die platform 12 and the first telescopic cylinder 20 of which the fixed end is fixed on the baffle 100, the telescopic end of the second telescopic cylinder 21 is fixedly connected with the baffle 100, the telescopic end of the first telescopic cylinder 20, the split dies 10 and the baffle 100 are connected through a connecting rod mechanism, one end of the connecting rod mechanism is hinged on the telescopic end of the first telescopic cylinder 20, the other end articulates on the outer wall of minute mould 10 first connecting rod 101 and one end articulate on the outer wall of minute mould 10, the other end articulates on baffle 100 second connecting rod 102, and first telescoping cylinder 20 and second telescoping cylinder 21 can drive minute mould 10 and move along with baffle 100 so that baffle 100 shelters from minute mould 10.
The test method of the test equipment comprises the following steps: starting a first telescopic cylinder 20 of a split die 10 controlled by the first telescopic cylinder to extend, enabling the split die 10 to approach to the other two split dies 10, starting the first telescopic cylinder 20 and a second telescopic cylinder 21 of the other two split dies to extend, enabling the two second telescopic cylinders 21 to drive respective baffle plates 100 to approach to each other, and enabling the two split dies 10 to approach to each other by the driving of a first connecting rod 101 and a second connecting rod 102 until the three split dies 10 surround and form an inner cavity with a load disc 30; then adding solid particle materials into the inner cavity in batches, wherein after each time of adding, the telescopic rod 70 drives the compaction piece 50 to compact the solid particle materials under the main stress (such as 10kPa), and during the compaction process of the compaction piece 50, the handle 80 is rotated to drive the load disk 30 to rotate so as to compress the solid particle materials; after the sample preparation is finished, the telescopic cylinders are shortened to drive the split dies 10 to separate, the telescopic rods 70 drive the compaction pieces 50 to apply shearing force to the prepared sample, the force is measured by the load sensor 40, and the maximum shearing force when the material is crushed is read, wherein the maximum shearing force is the unconstrained yield stress. The above operations were repeated to compact the solid particulate materials at different principal stresses (e.g., 10kPa, 20kPa … … 100kPa, etc.), and the respective unconstrained yield stresses of these materials were measured, with the results shown in fig. 13.
As can be seen from the above description, the present invention has the following advantages: a sample preparation inner cavity is defined by a plurality of sub-moulds 10, after sample preparation is finished, each sub-mould 10 is separated, and then shearing test is carried out, so that the influence of the friction force of the inner wall of the mould on the test result in the prior art is avoided, and the test result is more accurate; sample preparation and test are carried out on the test equipment, so that the test flow is shortened, and unexpected factors caused by overlong flow are avoided; the solid particle material can be fed in batches, the porosity of the solid particle material is close to that of a direct shearing sample after each feeding and compaction, the test result of the solid particle material is also close to that of the direct shearing sample, the solid particle material is maintained along with the depth, and the measurement accuracy is high. The loading disc 30 can be rotatably arranged and rotates during sample preparation, so that the further compaction state of the sample can be improved, and the accuracy of a subsequent test result is ensured. Part or whole headstock gear contain baffle 100, not only can give whole structure extra support for when the preparation sample that awaits measuring, the inner chamber structure is more stable, can also prevent that the material from splashing, effectively protects operating personnel. The load sensor 40 is connected between the telescopic rod 70 and the compaction piece 50, and after sample preparation is completed, a shear test can be directly carried out on a sample, so that the test flow is greatly shortened.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
1. Apparatus for testing the shear stress of a solid particulate material, comprising:
a load tray (30);
a plurality of sub-moulds (10), wherein each sub-mould (10) and the loading tray (30) enclose an inner cavity which takes the loading tray (30) as a bottom and the sub-mould (10) as a side wall and is used for compacting and forming the solid granular material;
the opening and closing device is connected outside each split mold (10) and respectively controls the opening and closing of each split mold (10); and
a compaction device located above the inner cavity,
wherein, the compaction device comprises a telescopic rod (70) and a compaction piece (50) which are connected in sequence from top to bottom, and the telescopic rod (70) can drive the compaction piece (50) to compact the solid particle material in the inner cavity.
2. A test apparatus for shear stress of solid particulate material according to claim 1, wherein the load tray (30) is connected to the chassis (11) of the test apparatus by a rotatable rod (31), the rotatable rod (31) having a handle (80) connected thereto.
3. The apparatus for testing the shear stress of solid particulate materials according to claim 1, wherein a discharge hopper (90) is obliquely disposed below the loading tray (30).
4. Apparatus for testing the shear stress of a solid particulate material according to claim 1, further comprising a mould platform (12), said opening and closing means being supported by said mould platform (12).
5. The apparatus for testing the shear stress of solid particulate material according to claim 4, wherein said opening and closing means comprise a first telescopic cylinder (20) connected to said mould platform (12), said first telescopic cylinder (20) being hinged on the outer wall of said split mould (10).
6. The apparatus for testing shear stress of solid particulate material according to claim 5, wherein the opening and closing device further comprises a baffle (100) and a connecting rod mechanism, the connecting rod mechanism comprises a first connecting rod (101) having one end hinged to the end of the piston rod of the first telescopic cylinder (20) and the other end hinged to the outer wall of the split mold (10), and a second connecting rod (102) having one end hinged to the outer wall of the split mold (10) and the other end hinged to the baffle (100), and the first telescopic cylinder (20) can drive the baffle (100) to move along with the split mold (10) to shield the split mold (10).
7. The solid particle material shear stress test equipment according to claim 4, wherein the opening and closing device comprises a baffle plate (100) slidably arranged on the mold platform (12), a second telescopic cylinder (21) fixed at the bottom of the mold platform (12), and a first telescopic cylinder (20) fixed at a fixed end on the baffle plate (100), wherein a telescopic end of the second telescopic cylinder (21) is fixedly connected with the baffle plate (100), a telescopic end of the first telescopic cylinder (20), the split mold (10) and the baffle plate (100) are connected through a connecting rod mechanism, the connecting rod mechanism comprises a first connecting rod (101) with one end hinged on the telescopic end of the first telescopic cylinder (20) and the other end hinged on the outer wall of the split mold (10), and a second connecting rod (102) with one end hinged on the outer wall of the split mold (10) and the other end hinged on the baffle plate (100), the first telescopic cylinder (20) and the second telescopic cylinder (21) can drive the split die (10) to move along with the baffle (100) so that the baffle (100) can shield the split die (10).
8. The apparatus for testing the shear stress of a solid particulate material according to claim 6 or 7, wherein the die platform (12) is provided with a limiting groove of the baffle (100).
9. Apparatus for testing the shear stress of solid particulate material according to any one of claims 1 to 7, characterized in that a load cell (40) is connected between the telescopic rod (70) and the compacting member (50), the telescopic rod (70) being capable of moving the compacting member (50) to apply a shear force to the solid particulate material being compacted, the load cell (40) measuring the shear force.
10. A method for testing the shear stress of a solid particle material is characterized by comprising the following steps:
1) starting the opening and closing device, closing each sub-mold (10) to form an inner cavity formed by compacting the solid granular material together with the load disc (30);
2) adding the solid particulate material to the internal cavity and compacting;
3) repeating step 2) a plurality of times until the inner cavity is filled with the compacted solid particulate material;
4) starting the opening and closing device, separating the split dies (10), applying a shearing force to the split dies from above the material and measuring the shearing force.
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