CN112146986B - Passive confining pressure loading device and method for split Hopkinson pressure bar - Google Patents
Passive confining pressure loading device and method for split Hopkinson pressure bar Download PDFInfo
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- CN112146986B CN112146986B CN202011136100.9A CN202011136100A CN112146986B CN 112146986 B CN112146986 B CN 112146986B CN 202011136100 A CN202011136100 A CN 202011136100A CN 112146986 B CN112146986 B CN 112146986B
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- 238000011068 loading method Methods 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims abstract description 11
- 238000012360 testing method Methods 0.000 claims abstract description 79
- 238000009434 installation Methods 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims description 25
- 229910052751 metal Inorganic materials 0.000 claims description 25
- 230000003068 static effect Effects 0.000 claims description 16
- 235000014121 butter Nutrition 0.000 claims description 6
- 239000007822 coupling agent Substances 0.000 claims description 6
- 229940099259 vaseline Drugs 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 239000011888 foil Substances 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 5
- 238000012423 maintenance Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 13
- 230000009471 action Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
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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
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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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
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/04—Chucks, fixtures, jaws, holders or anvils
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
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- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides a passive confining pressure loading device for a split Hopkinson pressure bar, which comprises a detachable clamping device (2), wherein the detachable clamping device (2) is provided with a through hole (5) for accommodating a test piece (6), and positioning components are arranged on two sides of the through hole (5); the front end and the rear end of the test piece (6) are provided with an incidence rod (1) and a projection rod (4) in a matching way. The invention also provides a passive confining pressure loading method for the split Hopkinson pressure bar. According to the invention, the test accuracy of the test piece is improved through the structure with the detachable upper and lower parts and the positioning part; according to the invention, the device can be finely adjusted through the cooperation among the graduated scale, the positioning groove, the positioning block and the bolt and the nut, so that the test piece is ensured to be in a passive confining pressure state in the test process. The invention has simple structure and convenient installation and disassembly; can realize the precision that the test piece was placed, be convenient for later maintenance.
Description
Technical Field
The invention relates to the technical field of dynamic mechanical property test and research of materials, in particular to a passive confining pressure loading device and method for a split Hopkinson pressure bar.
Background
In the wide fields of scientific research, engineering technology and the like, dynamic load problems such as blasting impact, mechanical disturbance, earthquake action and the like are frequently encountered. The strain rate effect of the mechanical properties of the material caused by the high-amplitude short-duration pulse and load is very important for the structural design and analysis of the anti-dynamic load. The split Hopkinson pressure bar is recognized as the most commonly used and effective experimental equipment for researching the mechanical properties of materials under the action of impulse dynamic load.
In studying the dynamic problem under high strain rate in split hopkinson struts, most materials need to be made into samples that match the struts. The original stress state of the material is quite complex, and can be a state without external force, a one-dimensional stress state or a multidimensional stress state, and the situation of passively controlling the free surface of the material often occurs in engineering sites. If the simulated material is affected by passive confining pressure, no pressure tight constraint is required to be applied to the side surface of the sample in the material test.
At present, the passive confining pressure loading device is mostly a steel sleeve with a diameter slightly larger than the rod diameter, and the initial position is not easy to determine when materials are put into the device; the materials are difficult to put in and take out during dynamic loading, and particularly the brittle materials are easy to break when the brittle materials are taken out after the test is finished; particularly, for brittle materials with lower strength, the non-pressure tight constraint on the side surface of the sample cannot be ensured, the sample cannot be ensured to be in a passive confining pressure state, and the test result deviation is caused.
Based on the above, a device and a method for passive confining pressure loading of a split Hopkinson pressure bar, which are accurate in loading, accurate in positioning, simple in structure and convenient to operate, are urgently needed.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a separated Hopkinson pressure bar passive confining pressure loading device and a method thereof, which achieve the aims of accurate loading and positioning of the passive confining pressure device, easy installation of a test piece and ensuring that the test piece is in a passive confining pressure state.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
The passive confining pressure loading device for the split Hopkinson pressure bar comprises a detachable clamping device, wherein the detachable clamping device is provided with a through hole for accommodating a test piece, and positioning components are arranged on two sides of the through hole; the front end and the rear end of the test piece are matched and provided with an incidence rod and a projection rod.
Further, the detachable clamping device comprises an upper semicircular sleeve and a lower semicircular sleeve, the upper semicircular sleeve and the lower semicircular sleeve are detachably connected through bolts and nuts, the through holes are formed by assembling the upper semicircular sleeve and the lower semicircular sleeve, and the positioning parts are scale marks respectively arranged on the lower end mounting surfaces of the upper semicircular sleeve and the lower semicircular sleeve and the upper end mounting surface; before assembly, the test piece is positioned in the lower semicircular sleeve through scale marks and an initial position is determined.
Furthermore, the lower end installation surfaces and the upper end installation surfaces of the upper semicircular sleeve and the lower semicircular sleeve are also provided with positioning blocks and positioning grooves which are matched with each other.
Further, the surface of the test piece is wrapped with a metal sheet, a strain gauge is stuck to the inner surface of the upper side of the through hole, and the strain gauge is connected with the static strain gauge through a leg wire connecting bridge circuit.
Further, the thickness of the metal sheet is 0.02-0.2mm, and the metal sheet is coated with the couplant.
Further, the coupling agent is vaseline or butter.
Further, the inner diameter of the through hole is slightly larger than the rod diameters of the incident rod and the projection rod.
Further, the detachable clamping device is made of stainless steel.
In order to achieve the above purpose, the invention also provides a passive confining pressure loading method for the split Hopkinson pressure bar, which comprises the following steps:
S1, correspondingly placing a test piece between an incident rod and a projection rod on the joint surface of a lower semicircular sleeve, adjusting the test piece to a proper position, observing scales, and determining the position of a scale interval where the test piece is positioned;
S2, taking out the incident rod, the projection rod and the test piece, and uniformly coating a layer of couplant on the joint surface of the semicircular sleeve at the corresponding lower side of the scale interval position of the test piece;
S3, cutting a metal sheet, wrapping the test piece by using the metal sheet, and matching the metal sheet with the test piece in size;
s4, placing the incidence rod, the projection rod and the test piece which is wrapped with the metal sheet and is positioned in the determined scale interval position and sequentially leaning against the test piece so as to clamp the test piece;
S5, attaching a strain gauge on the bonding surface of the upper semicircular sleeve, and lightly placing the strain gauge on the lower semicircular sleeve, wherein a strain gauge foot line is connected with a static strain gauge through a bridge circuit;
s6, opening a static strain gauge, starting to set related parameters when the screen has digital display, adjusting the parameters according to the change of a test piece, balancing a bridge, and pressing a start button to prepare calibration;
and S7, adjusting the bolts and nuts in a diagonal mode, so that the stress is uniform, the tightness of the test piece is slightly adjusted, the static strain gauge number is observed while adjusting, and when the static strain gauge number is about 10 mu epsilon, the non-pressure tight constraint state is considered to be reached, and the loading calibration adjustment is completed.
Further, the coupling agent is vaseline or butter, and the metal sheet is a copper sheet.
The beneficial effects are that: according to the invention, the test accuracy of the test piece is improved through the structure with the detachable upper and lower parts and the positioning part; according to the invention, the device can be finely adjusted through the cooperation among the graduated scale, the positioning groove, the positioning block and the bolt and the nut, so that the test piece is ensured to be in a passive confining pressure state in the test process. The invention has simple structure and convenient installation and disassembly; can realize the precision that the test piece was placed, be convenient for later maintenance.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a top view of a passive confining pressure loading device for a split Hopkinson pressure bar according to an embodiment of the invention;
FIG. 2 is a schematic end-face structure of a detachable clamping device according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a fitting structure of a detachable clamping device, a test piece and an incident rod according to an embodiment of the present invention;
FIG. 4 is a schematic side view of a detachable clamping device according to an embodiment of the present invention;
fig. 5 is a schematic perspective view of a lower half sleeve according to an embodiment of the present invention.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention will be described in detail below with reference to the drawings in connection with embodiments.
Example 1
See fig. 1-5: the passive confining pressure loading device for the split Hopkinson pressure bar comprises a detachable clamping device 2, wherein the detachable clamping device 2 is provided with a through hole 5 for accommodating a test piece 6, and positioning components are arranged on two sides of the through hole 5; the front end and the rear end of the test piece 6 are matched and provided with an incidence rod 1 and a projection rod 4.
In addition, the test piece is conveniently positioned through the positioning component and the through hole, and favorable conditions are provided for smooth and accurate loading process.
See fig. 2, 5: in a specific example, the detachable clamping device 2 includes an upper semicircular sleeve 7 and a lower semicircular sleeve 8, the upper semicircular sleeve 7 and the lower semicircular sleeve 8 are detachably connected through a bolt and nut 3, the upper semicircular sleeve 7 and the lower semicircular sleeve 8 are assembled to form the through hole 5, and the positioning components are scale marks 11 respectively arranged on the lower end mounting surfaces of the upper semicircular sleeve 7 and the lower semicircular sleeve 8 and the upper end mounting surface; before assembly, the test piece 6 is positioned in the lower semicircular sleeve 8 by the graduation marks 11 and an initial position is determined.
According to the embodiment, a test piece is positioned and installed through scale marks, an incident rod and a projection rod are installed front and back after positioning is confirmed, and then the upper semicircular sleeve and the lower semicircular sleeve are screwed through bolts and nuts. In addition, it should be noted that, the tightness between the upper side semicircle sleeve and the lower side semicircle sleeve can be adjusted through the bolts and the nuts in the embodiment, so that the size of the through hole is properly adjusted, the test piece is in a passive confining pressure state in the test process, and the test accuracy is improved.
Preferably, the lower end mounting surfaces and the upper end mounting surfaces of the upper semicircular sleeve 7 and the lower semicircular sleeve 8 are also provided with a positioning block 9 and a positioning groove 10 which are matched with each other.
The positioning block and the positioning groove can effectively position and install the upper semicircular sleeve and the lower semicircular sleeve, and the mounting position is effectively prevented from being inclined by matching with the bolts and the nuts, so that the testing accuracy is improved; in addition, it can be understood that because the positioning groove has a certain depth, the process of tightness between the upper side semicircular sleeve and the lower side semicircular sleeve which are adjusted by the bolts and the nuts is more accurate, and the displacement is prevented.
Specifically, the surface of the test piece 6 is wrapped with a metal sheet, a strain gauge is stuck to the inner surface of the upper side of the through hole 5, and the strain gauge is connected with a static strain gauge through a leg wire connecting bridge circuit.
It should be noted that the length and width of the metal sheet in this embodiment are not greater than the perimeter and width of the test piece, i.e. the surface of the test piece is wrapped with a layer of matched metal sheet; in addition, the metal sheet of the present embodiment may preferably be a copper sheet; according to the embodiment, the static strain gauge is used for testing the strain parameters of the dynamic observation test piece, and the tightness of the detachable clamping device can be timely adjusted to achieve a proper state.
Specifically, the thickness of the metal sheet is 0.02-0.2mm, the metal sheet is coated with a coupling agent, the coupling agent is vaseline or butter, the inner diameter of the through hole 5 is slightly larger than the rod diameters of the incident rod 1 and the projection rod 4, and the detachable clamping device 2 is made of stainless steel.
The thickness of the metal sheet in this embodiment is reasonably selected according to the size of the test piece, and the couplant mainly plays roles of reducing friction and lubrication. The through-hole size of this embodiment can realize the precision that the test piece was placed, and through bolt and nut convenient to detach installation and regulation.
Example 2
In order to achieve the above objective, the present embodiment further provides a passive confining pressure loading method for a split hopkinson pressure bar, including the following steps:
S1, correspondingly placing a test piece between an incident rod and a projection rod on the joint surface of a lower semicircular sleeve, adjusting the test piece to a proper position, observing scales, and determining the position of a scale interval where the test piece is positioned;
S2, taking out the incident rod, the projection rod and the test piece, and uniformly coating a layer of couplant on the joint surface of the semicircular sleeve at the corresponding lower side of the scale interval position of the test piece;
S3, cutting a metal sheet, wrapping the test piece by using the metal sheet, and matching the metal sheet with the test piece in size;
s4, placing the incidence rod, the projection rod and the test piece which is wrapped with the metal sheet and is positioned in the determined scale interval position and sequentially leaning against the test piece so as to clamp the test piece;
S5, attaching a strain gauge on the bonding surface of the upper semicircular sleeve, and lightly placing the strain gauge on the lower semicircular sleeve, wherein a strain gauge foot line is connected with a static strain gauge through a bridge circuit;
s6, opening a static strain gauge, starting to set related parameters when the screen has digital display, adjusting the parameters according to the change of a test piece, balancing a bridge, and pressing a start button to prepare calibration;
and S7, adjusting the bolts and nuts in a diagonal mode, so that the stress is uniform, the tightness of the test piece is slightly adjusted, the static strain gauge number is observed while adjusting, and when the static strain gauge number is about 10 mu epsilon, the non-pressure tight constraint state is considered to be reached, and the loading calibration adjustment is completed.
The passive confining pressure loading method for the split type hopkinson pressure lever in the embodiment has the same advantages as those of the passive confining pressure loading device for the split type hopkinson pressure lever in the prior art, and is not described herein.
Specifically, the coupling agent is vaseline or butter, and the metal sheet is a copper sheet.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (3)
1. The passive confining pressure loading device for the split Hopkinson pressure bar is characterized by comprising a detachable clamping device (2), wherein the detachable clamping device (2) is provided with a through hole (5) for accommodating a test piece (6), and positioning components are arranged on two sides of the through hole (5); the front end and the rear end of the test piece (6) are matched and provided with an incidence rod (1) and a projection rod (4), the detachable clamping device (2) comprises an upper semicircular sleeve (7) and a lower semicircular sleeve (8), the upper semicircular sleeve (7) and the lower semicircular sleeve (8) are detachably connected through a bolt and a nut (3), the through hole (5) is formed by assembling the upper semicircular sleeve (7) and the lower semicircular sleeve (8), and the positioning component is a lower end mounting surface of the upper semicircular sleeve (7) and the lower semicircular sleeve (8) and a scale mark (11) on the upper end mounting surface; before assembly, test piece (6) pass through scale mark (11) location place in downside semicircle sleeve (8) and confirm initial position, still be equipped with locating piece (9) and constant head tank (10) that mutually match on the lower extreme installation face and the upper end installation face of upside semicircle sleeve (7) and downside semicircle sleeve (8), test piece (6) surface parcel has the sheetmetal, the upper side internal surface of through-hole (5) is pasted and is had the foil gage, the foil gage passes through foot line connection bridge and is connected with static strain gauge, the thickness of sheetmetal is 0.02-0.2mm, scribbles the couplant on the sheetmetal, the couplant is vaseline or butter, the internal diameter of through-hole (5) is slightly greater than the pole footpath of incident rod (1) and projection pole (4), detachable clamping device (2) are stainless steel.
2. A loading method for a split hopkinson ram passive confining pressure loading device as claimed in claim 1 including the steps of:
S1, correspondingly placing a test piece between an incident rod and a projection rod on the joint surface of a lower semicircular sleeve, adjusting the test piece to a proper position, observing scales, and determining the position of a scale interval where the test piece is positioned;
S2, taking out the incident rod, the projection rod and the test piece, and uniformly coating a layer of couplant on the joint surface of the semicircular sleeve at the corresponding lower side of the scale interval position of the test piece;
S3, cutting a metal sheet, wrapping the test piece by using the metal sheet, and matching the metal sheet with the test piece in size;
s4, placing the incidence rod, the projection rod and the test piece which is wrapped with the metal sheet and is positioned in the determined scale interval position and sequentially leaning against the test piece so as to clamp the test piece;
s5, attaching a strain gauge on the bonding surface of the upper semicircular sleeve, and lightly placing the strain gauge on the lower semicircular sleeve, wherein a strain gauge foot line is connected with a static strain gauge through a bridge circuit;
s6, opening a static strain gauge, starting to set related parameters when the screen has digital display, adjusting the parameters according to the change of a test piece, balancing a bridge, and pressing a start button to prepare calibration;
and S7, adjusting the bolts and nuts in a diagonal mode, so that the stress is uniform, the tightness of the test piece is slightly adjusted, the static strain gauge number is observed while adjusting, and when the static strain gauge number is about 10 mu epsilon, the non-pressure tight constraint state is considered to be reached, and the loading calibration adjustment is completed.
3. The method for loading the split hopkinson pressure bar passive confining pressure loading device according to claim 2 wherein the coupling agent is vaseline or butter and the metal sheet is a copper sheet.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011136100.9A CN112146986B (en) | 2020-10-22 | 2020-10-22 | Passive confining pressure loading device and method for split Hopkinson pressure bar |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011136100.9A CN112146986B (en) | 2020-10-22 | 2020-10-22 | Passive confining pressure loading device and method for split Hopkinson pressure bar |
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| CN112146986A CN112146986A (en) | 2020-12-29 |
| CN112146986B true CN112146986B (en) | 2024-07-23 |
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| CN213422808U (en) * | 2020-10-22 | 2021-06-11 | 安徽理工大学 | Passive confining pressure loading device for split Hopkinson pressure bar |
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| CN109708955A (en) * | 2019-01-17 | 2019-05-03 | 浙江大学 | A kind of positioning device for Hopkinson pressure bar |
| CN109813618B (en) * | 2019-03-19 | 2023-08-22 | 河南理工大学 | Vertical Hopkinson pressure bar test device and test method |
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