CN213749417U - Static semi-circular disc three-point bending fracture toughness measuring device under warm-pressing environment - Google Patents
Static semi-circular disc three-point bending fracture toughness measuring device under warm-pressing environment Download PDFInfo
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- CN213749417U CN213749417U CN202022062478.0U CN202022062478U CN213749417U CN 213749417 U CN213749417 U CN 213749417U CN 202022062478 U CN202022062478 U CN 202022062478U CN 213749417 U CN213749417 U CN 213749417U
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- 238000013001 point bending Methods 0.000 title claims abstract description 31
- 230000003068 static effect Effects 0.000 title claims abstract description 11
- 238000007789 sealing Methods 0.000 claims abstract description 26
- 239000012530 fluid Substances 0.000 claims abstract description 9
- 230000000007 visual effect Effects 0.000 claims abstract description 8
- 238000005485 electric heating Methods 0.000 claims description 12
- 230000006835 compression Effects 0.000 claims description 7
- 238000007906 compression Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 abstract description 19
- 238000012360 testing method Methods 0.000 abstract description 14
- 238000000034 method Methods 0.000 abstract description 10
- 239000004567 concrete Substances 0.000 abstract description 5
- 239000011435 rock Substances 0.000 abstract description 5
- 230000000977 initiatory effect Effects 0.000 abstract description 2
- 239000011521 glass Substances 0.000 abstract 1
- 238000002474 experimental method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000007656 fracture toughness test Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000000452 restraining effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
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Abstract
A static semicircular disc three-point bending fracture toughness measuring device in a warm-pressing environment belongs to the technical field of engineering such as machinery, engineering geology, civil engineering and the like, is used for testing fracture toughness of brittle materials such as rocks, concrete, glass and the like in a controllable temperature and fluid pressure environment, and comprises a warm-pressing control device, a semicircular disc three-point bending loading device and a sample clamping device; the semi-circular disc three-point bending loading device is located inside the temperature control device, and the sample clamping device is located on a movable bottom plate of the semi-circular disc three-point bending loading device. The method can observe crack initiation and propagation processes in real time through the visual window in the test, and can timely eliminate invalid experimental data; the loading part and the sample taking part are mutually independent, so that the reduction of the sealing performance and the increase of the test error caused by inaccurate positioning of the loading part during multiple use are prevented, and the fluid consumption and the power consumption required by pressurization are saved.
Description
Technical Field
The invention belongs to the technical field of experimental equipment for elastic and brittle materials such as rocks, concrete and the like in engineering mechanics, and relates to a static semicircular disc three-point bending fracture toughness measuring device, in particular to a device capable of measuring fracture toughness of a material in a gas or liquid environment with controllable temperature and pressure.
Background
The test of the fracture toughness of the material is used for establishing the crack propagation criterion of fracture mechanics. The critical load of failure can be further determined by the crack propagation criterion in combination with the geometry of the actual problem; for complex problems, the method can also be used for establishing a crack propagation model in numerical calculation to obtain the damage form of the structure, so that the method is used for the fields of optimizing structure design, evaluating the bearing capacity of the existing structure and the like.
At present, a static semicircular disc three-point bending test is mainly used for measuring the fracture toughness of elastic and brittle materials such as rocks, concrete and the like. For these elasto-brittle materials, existing methods for measuring fracture toughness include: three-point bending of the semicircular disc, splitting of the Brazilian disc, three-point bending of the beam, compact stretching and the like, and the three-point bending test of the semicircular disc is widely applied due to simple implementation and material saving of a sample. At present, three-point bending experiments on materials are mostly carried out at normal temperature and normal pressure, in the experiments, the semicircular disc is provided with prefabricated cracks along a symmetry axis, when the stress of the top and two angular points of the disc reaches a certain critical value, the semicircular disc is damaged due to crack propagation, and the fracture toughness of the materials is deduced through the critical value.
However, many materials are in fluid environments other than normal temperature and pressure for a long time, such as: the fracture toughness test of natural oil and gas reservoirs with depths of thousands of meters underground, concrete in nuclear facilities and the like needs to simulate the real environment in which the materials are located. With the increase of temperature, the material shows the phenomena of rigidity reduction, plasticity increase, strength weakening, creep enhancement and the like; as the pressure rises, the internal pores of the rock, concrete, etc. material are compressed, and their mechanical properties will further change. If the measurement is continuously carried out at normal temperature and normal pressure, the fracture toughness of the material is not equal to the value in the real environment.
Disclosure of Invention
In order to overcome the defect that the existing semi-circular disc three-point bending equipment cannot measure the fracture toughness of the material in a warm-pressing environment, the invention provides a testing device which can adjust the temperature and the pressure of a liquid or gas environment where a sample is located and simulate the real environment where the material is located.
The technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides a static semicircle dish three point bending fracture toughness measuring device under warm-pressing environment which characterized in that: the device comprises a temperature and pressure control device, a semi-circular disc three-point bending loading device and a sample clamping device; the semi-circular disc three-point bending loading device is positioned in the temperature control device, and the sample clamping device is positioned on a movable bottom plate of the semi-circular disc three-point bending loading device; the temperature and pressure control device comprises a heating wire power supply box, a pressure gauge, a pressure control servo pump, a cylindrical kettle body, a pressure kettle top cover and a pressure kettle bottom cover, wherein the pressure kettle bottom cover is arranged at the lower part of the cylindrical kettle body; the semi-circular disc three-point bending loading device comprises a cylindrical pressing column, a semi-cylindrical pressing head, a semi-cylindrical support and a movable bottom plate, wherein the semi-cylindrical pressing head is fixed at the bottom end of the cylindrical pressing column; the sample clamping device comprises a front positioning column, a rear positioning column, a sliding soft rod and a positioning bolt; the sliding sleeve of the sliding soft rod is sleeved on the front side positioning column, the semi-cylindrical support is arranged between the front side positioning column and the rear side positioning column, and the positioning bolt is arranged on the front side positioning column and is positioned between the sliding soft rod and the semi-cylindrical support.
In order to ensure the sealing performance, the compression leg sealing ring and the movable bottom plate sealing ring are used for sealing fluid in the pressure kettle, the circular sealing guide ring is arranged at the top end of the pressure kettle, the upper end of the circular sealing guide ring is in contact with the top cover, and the lower end of the circular sealing guide ring is in contact with the bulge on the inner wall surface of the pressure kettle.
In order to ensure the positioning, the cylindrical compression leg is connected with a positioning key, guide grooves are axially and symmetrically distributed on the top cover of the pressure kettle, the guide grooves are matched with the positioning key for use, and the positioning grooves are symmetrically distributed on the movable bottom plate for positioning the bottom plate.
In order to ensure that the temperature and the pressure are controllable, the insulating layer and the electric heating wire respectively form a tubular structure at the outer side and the inner side and are adhered to the inner wall surface of the pressure kettle, and the pressure gauge and the servo pump jointly ensure that the pressure in the kettle is maintained at a specific value.
The invention has the beneficial effects that: the fracture toughness of the material can be measured under the environment with controllable temperature and pressure, and the real environment of the material can be simulated; crack initiation and propagation processes can be observed in real time in the test, and invalid experimental data can be eliminated in time; the loading part and the sample taking part are mutually independent, so that the reduction of the sealing performance and the increase of the test error caused by inaccurate positioning of the loading part during multiple use are prevented, and the fluid consumption and the power consumption required by pressurization are saved.
Drawings
FIG. 1 is an external view of the device of the present invention.
FIG. 2 is a block diagram of the apparatus of the present invention.
Fig. 3 is a structural view of the sample holder on the movable base plate.
Fig. 4 is a sample shape diagram.
In the drawing, 1, a cylindrical pressing column, 2, a pressure kettle top cover, 3, a pressure gauge, 4, a pressure control servo pump, 5, a pressure kettle bottom cover, 6, a visual window, 7, an electric heating wire power supply box, 8, a positioning key, 9, a guide groove, 10, a first sealing ring, 11, a circular sealing guide ring, 12, a second sealing ring, 13, an insulating layer and an electric heating wire, 14, a fluid pipeline, 15, a third sealing ring, 16, a positioning groove, 17, a semi-cylindrical pressing head, 18, a sample, 19, an electric resistance wire power supply channel, 20, a semi-cylindrical support, 21, a movable bottom plate, 22, a rear positioning column, 23, a sliding soft rod, 24, a positioning bolt and 25, a front positioning column are arranged.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
Fig. 1, fig. 2 and fig. 3 show a static semicircular disc three-point bending fracture toughness measurement device under a warm-pressing environment, which is characterized in that: the device comprises a temperature and pressure control device, a semi-circular disc three-point bending loading device and a sample clamping device; the semi-circular disc three-point bending loading device is positioned in the temperature control device, and the sample clamping device is positioned on a movable bottom plate (21) of the semi-circular disc three-point bending loading device; the temperature and pressure control device comprises an electric heating wire power supply box (7), a pressure gauge (3), a pressure control servo pump (4), a cylindrical kettle body, a pressure kettle top cover (2) and a pressure kettle bottom cover (5), wherein the pressure kettle bottom cover (5) is arranged at the lower part of the cylindrical kettle body, the pressure kettle top cover (2) is arranged at the top of the cylindrical kettle body, a visual window (6) is arranged in the middle of the cylindrical kettle body, the visual window (6) is fixedly connected with the kettle body, the pressure control servo pump (4) is connected with the kettle body through a pipeline, and the electric heating wire power supply box (7) is connected with the kettle body through a power supply line; the semi-disc three-point bending loading device comprises a cylindrical pressing column (1), a semi-cylindrical pressure head (17), a semi-cylindrical support (20) and a movable bottom plate (21), wherein the semi-cylindrical pressure head (17) is fixed at the bottom end of the cylindrical pressing column (1), the semi-cylindrical support (20) is fixed with the movable bottom plate (21) and is positioned on the movable bottom plate (21), and a sample is placed on the semi-cylindrical support (20) and is positioned under the semi-cylindrical pressure head (17); the sample clamping device comprises a front positioning column (22), a rear positioning column (25), a sliding soft rod (23) and a positioning bolt (24); the sliding sleeve of the sliding soft rod (23) is sleeved on the front side positioning column (22), the semi-cylindrical support (20) is arranged between the front side positioning column (22) and the rear side positioning column (25), and the positioning bolt (24) is arranged on the front side positioning column (22) and is positioned between the sliding soft rod (23) and the semi-cylindrical support (20).
In fig. 1, a top cover (2) and a bottom cover (5) of the pressure kettle are in threaded connection with a kettle body, and the side surface of the pressure kettle is provided with a threaded hole for dismounting the device; the pipeline of the servo pump (4) and a power supply line of the electric heating wire power supply box (7) are in threaded connection with the kettle body; the visual window (6) is fixedly connected with the kettle body and ensures sealing. In fig. 2, the positioning key (8) is connected with the cylindrical compression column; the guide grooves (9) are symmetrically distributed on the top cover of the pressure kettle and are matched with the positioning keys for use; the sealing ring is used for sealing fluid in the pressure kettle, and a group of multi-channel rings are used for improving the sealing property; the circular sealing guide ring (12) is arranged at the top end of the pressure kettle, the upper end of the circular sealing guide ring is contacted with the top cover, and the lower end of the circular sealing guide ring is contacted with the bulge on the inner wall surface of the pressure kettle; the insulating layer and the electric heating wire (13) form a tubular structure at the outer side and the inner side respectively and are stuck on the inner wall surface of the pressure kettle; the positioning grooves (16) are symmetrically distributed at the bottom of the pressure kettle body and used for positioning the bottom plate; the semi-cylinder pressure head (17) is fixed at the bottom end of the cylinder pressure column; the semi-cylinder support (20) is fixed on the bottom plate. In fig. 3, two positioning columns are welded on the movable bottom plate, a sliding soft rod (23) is used for sliding up and down on the rear positioning column (22) and restraining the movement of the sample in the up-down, left-right directions, and a positioning bolt (23) is used for restraining the movement of the sample in the front-back direction.
The method comprises the following steps:
(1) according to FIG. 4, the diameter D =76 mm, the thickness B ≧ 0.4D or 30 mm, the crack length a: 0.2-0.2 ≤a/DNot more than 0.3, support point spacing l: 0.5-0.5 ≤l/DProcessing a hemispherical sample by using parameters less than or equal to 0.8; the value of the geometric parameter is suggested to process the sample to be measured.
(2) The apparatus was connected completely, the autoclave was heated and pressurized for 5-10 minutes (about the time of the experiment), and the tightness, temperature and pressure were checked for constancy.
(3) The device is arranged on a compression testing machine, the pressure column is controlled to move at a constant speed to approach a stroke, and the resistance borne by the testing machine in the process is recordedF 0。
(4) And closing the electric heating wire switch, gradually reducing the pressure in the kettle body, and returning the pressing column.
(5) The autoclave was opened from the bottom, and the sample was put in and fixed with a set bolt and placed on a compression tester. The positioning of the bottom plate is noted, so that the semi-circle surface of the sample faces to one side of the visual window.
(6) Increasing the pressure to half of the measuring point, opening a switch of the electric heating wire to increase the temperature, and continuously and slowly increasing the pressure and the temperature to the measuring point.
(7) Controlling the pressure column to move at a constant speed until the force-displacement curve of the testing machine suddenly drops, and recording the maximum force borne by the testing machineF. Note that the tester displacement cannot exceed the plunger travel.
(8) Repeating (3) - (6) to complete the grouping repetition experiment.
(9) And (5) after the experiment is finished, arranging an experimental device and finishing the result.
According to the method recommended by the international society of rock mechanics, the maximum force applied by the tester in each experimentFAndF 0deducing the fracture toughness of the material as
D is the diameter of the sample, B is the thickness of the sample, B is more than or equal to 0.4D, a is the length of the crack, and a is more than or equal to 0.2a/DNot more than 0.3, l is the supporting point distance, 0.5 is not more thanl/D≤ 0.8，F 0Is the resistance measured by the testing machine in the step (3), and comprises mechanical friction and fluid pressure.
Claims (4)
1. The utility model provides a static semicircle dish three point bending fracture toughness measuring device under warm-pressing environment which characterized in that: the device comprises a temperature and pressure control device, a semi-circular disc three-point bending loading device and a sample clamping device; the semi-circular disc three-point bending loading device is positioned in the temperature control device, and the sample clamping device is positioned on a movable bottom plate (21) of the semi-circular disc three-point bending loading device; the temperature and pressure control device comprises an electric heating wire power supply box (7), a pressure gauge (3), a pressure control servo pump (4), a cylindrical kettle body, a pressure kettle top cover (2) and a pressure kettle bottom cover (5), wherein the pressure kettle bottom cover (5) is arranged at the lower part of the cylindrical kettle body, the pressure kettle top cover (2) is arranged at the top of the cylindrical kettle body, a visual window (6) is arranged in the middle of the cylindrical kettle body, the visual window (6) is fixedly connected with the kettle body, the pressure control servo pump (4) is connected with the kettle body through a pipeline, and the electric heating wire power supply box (7) is connected with the kettle body through a power supply line; the semi-disc three-point bending loading device comprises a cylindrical pressing column (1), a semi-cylindrical pressure head (17), a semi-cylindrical support (20) and a movable bottom plate (21), wherein the semi-cylindrical pressure head (17) is fixed at the bottom end of the cylindrical pressing column (1), the semi-cylindrical support (20) and the movable bottom plate (21) are fixed and located on the movable bottom plate (21), and a sample is placed on the semi-cylindrical support (20) and located under the semi-cylindrical pressure head (17); the sample clamping device comprises a front positioning column (22), a rear positioning column (25), a sliding soft rod (23) and a positioning bolt (24); the sliding sleeve of the sliding soft rod (23) is sleeved on the front side positioning column (22), the semi-cylindrical support (20) is arranged between the front side positioning column (22) and the rear side positioning column (25), and the positioning bolt (24) is arranged on the front side positioning column (22) and is positioned between the sliding soft rod (23) and the semi-cylindrical support (20).
2. The device for measuring the three-point bending fracture toughness of the static semicircular disc in the warm-pressing environment as claimed in claim 1, wherein: the compression leg sealing ring (10) and the movable bottom plate sealing ring (15) are used for sealing fluid in the pressure kettle, the circular sealing guide ring (12) is arranged at the top end of the pressure kettle, the upper end of the circular sealing guide ring is in contact with the top cover, and the lower end of the circular sealing guide ring is in contact with a bulge on the inner wall surface of the pressure kettle.
3. The device for measuring the three-point bending fracture toughness of the static semicircular disc in the warm-pressing environment as claimed in claim 1, wherein: the cylinder compression leg (1) is connected with a positioning key (8), guide grooves (9) are axially and symmetrically distributed on the top cover of the pressure kettle, the guide grooves (9) are matched with the positioning key for use, and positioning grooves (16) are symmetrically distributed on the movable bottom plate (21) for positioning the bottom plate.
4. The device for measuring the three-point bending fracture toughness of the static semicircular disc in the warm-pressing environment as claimed in claim 1, wherein: the insulating layer and the electric heating wire (13) form a pipe type structure respectively at the outer side and the inner side and are stuck on the inner wall surface of the pressure kettle.
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| CN202022062478.0U CN213749417U (en) | 2020-09-19 | 2020-09-19 | Static semi-circular disc three-point bending fracture toughness measuring device under warm-pressing environment |
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| CN202022062478.0U CN213749417U (en) | 2020-09-19 | 2020-09-19 | Static semi-circular disc three-point bending fracture toughness measuring device under warm-pressing environment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112161879A (en) * | 2020-09-19 | 2021-01-01 | 太原理工大学 | Device and method for measuring three-point bending fracture toughness of static semicircular disc in warm-pressing environment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112161879A (en) * | 2020-09-19 | 2021-01-01 | 太原理工大学 | Device and method for measuring three-point bending fracture toughness of static semicircular disc in warm-pressing environment |
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Granted publication date: 20210720 |