CN217006811U - Hard brittle material dynamic indentation experimental device based on Hopkinson pressure bar - Google Patents
Hard brittle material dynamic indentation experimental device based on Hopkinson pressure bar Download PDFInfo
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- CN217006811U CN217006811U CN202122793009.0U CN202122793009U CN217006811U CN 217006811 U CN217006811 U CN 217006811U CN 202122793009 U CN202122793009 U CN 202122793009U CN 217006811 U CN217006811 U CN 217006811U
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Abstract
The invention discloses a dynamic indentation experimental device for a hard and brittle material based on a Hopkinson pressure bar, which is characterized by comprising a striker bar, an incident bar, a transmission bar, a buffer block, a digital oscilloscope, a linear variable differential sensor, a super-dynamic strain gauge and a computer processing system, wherein a strain gauge is arranged between the incident bar and the transmission bar, the strain gauge is electrically connected with the super-dynamic strain gauge, a tested piece is arranged at the front end of the transmission bar, a pressure head is arranged at the rear end of the incident bar through a sleeve, a steel momentum trap component with flange-sleeve-rigid quality is arranged at the front end of the incident bar, a guide restraint device ensures that the incident bar, a workpiece and the transmission bar are positioned on the same axis, a speed measuring device is arranged at the front end of the incident bar, a force sensor is arranged at the rear end of the bar, and the internal damage of the test piece is recorded through an X-ray transmission device; the method has the advantages that the single indentation can be realized, the dynamic mechanical characteristics of the test piece and the development process of the internal damage under the high strain rate are obtained, and the dynamic damage characteristic response under the high strain rate is conveniently and deeply researched.
Description
Technical Field
The utility model relates to the field of measurement of dynamic mechanical properties of hard and brittle materials, in particular to a dynamic indentation experimental device for hard and brittle materials.
Background
At present, the existing indentation technology mainly focuses on static indentation experiments, such as common nano indentation experiments; the development of a dynamic indentation experiment technology is not mature, and the dynamic mechanical property of the material cannot be accurately measured; the crack propagation speed block under the dynamic load cannot track the damage initiation and the evolution in the deformation process under the dynamic load in the test piece; pulses cannot be controlled in experiments, and single indentation is difficult to realize; in the indentation experiment process, the relative position of the test piece and the experiment device is changed, so that the experiment result is influenced; due to the fact that the hardness of the hard and brittle material is high, the impact speed is high under the dynamic loading condition, and the service life of the incident rod can be shortened.
Disclosure of Invention
The purpose of the utility model is: in order to overcome the defects of the prior art, the utility model provides the hard and brittle material dynamic indentation experimental device which is high in measurement precision and capable of detecting the internal damage evolution of the material.
In order to realize the purpose of the utility model, the following technical scheme is adopted for realizing the purpose: a hard brittle material dynamic indentation experimental apparatus based on a Hopkinson pressure bar comprises: striking rod, light trigger speed sensor, buffer block, the variable differential sensor of linearity, installation foil gage in the middle of the pole of incidence and the transmission pole, transmission pole front end installation test piece, its characterized in that: the front end of an incident rod is provided with a momentum trap assembly consisting of a flange, a sleeve and a rigid mass, the rear end of the incident rod is provided with a pressure head through a pressure head sleeve, the same axis of the incident rod, a test piece and a transmission rod is ensured through a guide constraint device, a linear variable differential sensor is directly connected with the pressure head sleeve, the front end of the incident rod is provided with a light trigger speed measuring device, a force sensor is arranged between the transmission rod and a buffer block, and the internal damage of the test piece is monitored and recorded through an X-ray imaging device.
Preferably, the guiding and restraining device is a hollow cylinder with openings at the upper and lower parts of the front end and is made of transparent glass.
Preferably, the front end of the incidence rod is provided with a ' flange-sleeve-rigid mass ' momentum trap ' steel component, the rear end of the incidence rod is provided with a pressure head through a pressure head sleeve, and the pressure head sleeve is made of hard alloy and is in threaded connection with the pressure head sleeve.
Preferably, the linear variable differential sensor is fixedly connected with the pressure head sleeve through the baffle plate.
Preferably, the distance between the center and the edge of the test piece is at least 2.5 times of the diagonal of the indentation, so that the hardness measurement of the indentation cannot be influenced by the boundary effect, the thickness of the test piece is 1.5 times of the diagonal of the indentation, complete radial/middle cracks are contained, and complete fracture and crack information loss are avoided.
Preferably, the X-ray imaging device monitors and records the internal damage of the test piece.
Compared with the prior art, the experimental device has the advantages that the experimental device is used for carrying out dynamic indentation experiments on the hard and brittle materials, so that the problems that the joint of the pressure head sleeve and the incident rod generates local plastic deformation and the incident rod is damaged by the reaction force of the pressure head on the incident rod due to the fact that the hard and brittle materials are high in the traditional device are solved; the wave impedance mismatch problem of the pressure head and the incident rod is caused by the large difference of the cross section areas of the incident rod and the pressure head; the problem of a plurality of indentations generated in the experimental process is avoided by adopting a steel ' flange-sleeve-rigid mass ' momentum trap ' component; the shock is generated in the impact process, so that the relative positions of a pressure head, a tested piece and the like are changed; except a few transparent materials, the damage initiation and the evolution in the dynamic deformation process of the interior of the test piece can not be tracked. The dynamic mechanical property of the material can be accurately measured, and the development process of the internal damage of the material under high strain rate can be recorded and tracked.
Drawings
Fig. 1 illustrates the structural principle of the present invention.
Figure 2 illustrates the construction of the indenter sleeve.
1: a striker bar; 2: a light-triggered speed measuring device; 3: a flange; 4: a sleeve; 5: a rigid mass; 6: a momentum trap; 7: an incident rod; 8: a strain gauge; 9: a linear variable differential sensor; 10: a baffle plate; 11: a ram sleeve; 12; a pressure head; 13: a test piece; 14: an X-ray generator; 15: a scintillator; 16: a 45 ° mirror; 17: a microscope lens; 18: a high-speed camera; 19: a transmission rod; 20: a guide restraint device; 21: a force sensor; 22: and a buffer block.
Detailed Description
The key points of the utility model are as follows: when the striker rod 1 strikes the flange 3, a compression pulse is simultaneously generated in the sleeve 4 and the incident rod 7. Wherein the compression pulses (C) in the sleeve 4sleeve) When reaching the rigid mass 5, it will be reflected back to the flange 3 in the form of a stretching pulse, and when reaching the end of the flange 3, it will have a stretching pulse (T)sleeve) Loaded into the entrance bar 7. Compression pulse (C) in incident rod 7impact) The indentation required for the experiment is generated and then reflected to form a tension pulse (T)impact) Which is captured by the momentum trap assembly 6 when it reaches the end of the flange 3, and which is not sensed by the strain gauge in subsequent readings. Therefore, the strain gauge 8 is installed at the center of the incident rod 7 and the transmission rod 19, and the compression pulse (C) is recorded impact) Followed by a stretching pulse (T)sleeve) Both of which move toward the transmission rod 19. Initial stretching pulse (T)sleeve) Reaching the indenter 12 will cause the indenter 12 to separate from the test piece 13, followed by a compression pulse (C)sleeve) Is reflected back to the flange end and then pulsed with tension (T)sleeve) Reflects back to the head end. This process will be repeated several times, causing the indenter to retract and move away from the specimen. Thus, by properly designing the momentum trap 6, it is ensured that only one compression pulse reaches the end of the indenter, allowing dynamic indentation tests to be performed at high strain rates.
The duration of the input pulse can be varied by selecting different lengths of the striker rod 1 and the amplitude of the incident compressive stress pulse (or incident load) can be varied by varying the velocity of the incident rod 7. The linear variable differential sensor 9 is directly connected with the pressure head sleeve 11 through a baffle plate 10 to obtain an indentation depth time curve of a dynamic indentation experiment.
The optical trigger speed measuring device 2 is fixedly installed between the impact rod 1 and the incident rod 7, the optical trigger speed measuring device comprises a trigger timer, two laser tubes arranged side by side and two photosensitive tubes corresponding to the laser tubes from top to bottom, the photosensitive tubes are located below the laser tubes, the photosensitive tubes are electrically connected with the trigger timer, and the initial speed of the impact rod 1 can be obtained.
A force sensor 21 is arranged between the transmission rod 19 and the buffer block 22, and the force sensor 21 is used for in-situ measurement of pressure in a dynamic indentation experiment.
The X-ray emitter 14 emits X-rays which can penetrate through the dynamically loaded test piece 13, then the X-rays are converted into visible light through the scintillator 15 arranged below the test piece 13, the visible light is reflected by the 45-degree reflector 16 to pass through the 5-time or 10-time microscope lens 17, then the visible light finally enters the aperture of the high-speed camera 18, and the image of the internal damage evolution of the test piece is recorded after the visible light is amplified by the high-speed camera 18.
By the process, the mechanical data of the tested piece under the dynamic indentation and the development process of the material internal damage under the high strain rate can be obtained, the comparative analysis with the mechanical data under the quasi-static state is facilitated, and the material dynamic damage characteristic response under the high strain rate is deeply researched.
Claims (6)
1. A hard brittle material dynamic indentation experimental apparatus based on Hopkinson pressure bars comprises: striking rod (1), light trigger speed sensor (2), buffer block (22), linear variable differential sensor (9), and installation foil gage (8) in the middle of incident rod (7) and transmission rod (19), transmission rod (19) front end installation test piece (13), its characterized in that: "momentum trap" subassembly (6) that "flange (3) -sleeve (4) -rigidity quality (5)" constitution are equipped with to incidence pole (7) front end, the rear end passes through pressure head sleeve (11) installation pressure head (12), guarantee incidence pole (7) through direction restraint device (20), test piece (13), transmission rod (19) same axis, linear variable differential sensor (9) directly link to each other with pressure head sleeve (11), the incidence pole front end sets up light trigger speed measuring device (2), set up force sensor (21) between transmission rod (19) and buffer block (22), monitor and record the inside damage of test piece through X-ray image device.
2. The dynamic indentation experimental device for hard and brittle materials based on the Hopkinson pressure bar as claimed in claim 1, wherein the guiding and restraining device (20) is a hollow cylinder with openings at the upper and lower parts of the front end, and is made of transparent glass.
3. The dynamic indentation experimental device for the hard and brittle materials based on the Hopkinson pressure bar as claimed in claim 1, wherein a momentum trap steel component (6) of flange (3) -sleeve (4) -rigid mass (5) is mounted at the front end of the incident bar (7), a pressure head (12) is mounted at the rear end of the incident bar through a pressure head sleeve (11), and the pressure head sleeve is made of hard alloy and is in threaded connection with the pressure head sleeve.
4. The hard and brittle material dynamic indentation experimental device based on the Hopkinson pressure bar as claimed in claim 1, wherein the linear variable differential sensor (9) is fixedly connected with the indenter sleeve through a baffle (10).
5. The dynamic indentation experimental device for the hard and brittle materials based on the Hopkinson pressure bar as claimed in claim 1, wherein the distance between the center and the edge of the test piece (13) is at least 2.5 times of the diagonal line of the indentation, so that the hardness measurement of the indentation cannot be influenced by the boundary effect, and the thickness is 1.5 times of the diagonal line of the indentation, so that complete radial/middle cracks are contained, and complete fracture and crack information loss are avoided.
6. The dynamic indentation experimental device for hard and brittle materials based on Hopkinson pressure bars as claimed in claim 1, characterized in that an X-ray imaging device is used for monitoring and recording internal damage of the test piece (13).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202122793009.0U CN217006811U (en) | 2021-11-16 | 2021-11-16 | Hard brittle material dynamic indentation experimental device based on Hopkinson pressure bar |
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| CN202122793009.0U CN217006811U (en) | 2021-11-16 | 2021-11-16 | Hard brittle material dynamic indentation experimental device based on Hopkinson pressure bar |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115616370A (en) * | 2022-11-21 | 2023-01-17 | 北京理工大学 | System for testing electrical parameters of MOS control thyristor in impact environment |
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2021
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115616370A (en) * | 2022-11-21 | 2023-01-17 | 北京理工大学 | System for testing electrical parameters of MOS control thyristor in impact environment |
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