CN211122369U - Variable rod diameter Hopkinson pressure bar experimental device - Google Patents
Variable rod diameter Hopkinson pressure bar experimental device Download PDFInfo
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- CN211122369U CN211122369U CN201920992684.6U CN201920992684U CN211122369U CN 211122369 U CN211122369 U CN 211122369U CN 201920992684 U CN201920992684 U CN 201920992684U CN 211122369 U CN211122369 U CN 211122369U
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Abstract
The utility model discloses a variable rod diameter Hopkinson pressure bar experimental device, which comprises a three-jaw chuck, a transmitting system, an experimental rod system and a data acquisition and processing system; the launching system consists of an air pump, an air cylinder and a gun barrel, and the experimental rod system consists of an impact rod, an incident rod, a transmission rod and an absorption rod; the incident rod, the transmission rod and the absorption rod are sequentially and centrally clamped by a three-jaw chuck; the three-jaw chuck consists of a baffle plate, a base, a pneumatic chuck, a radial moving pawl, a roller, a pneumatic adjusting air inlet and a manual adjusting valve; the pneumatic chuck is connected with the air pump through a pneumatic adjusting air inlet; the roller moves the clamping end of the pawl in the radial direction, and the incident rod, the transmission rod and the absorption rod can slide on the roller; the device comprises a data acquisition processing system, a data acquisition processing system and a data acquisition processing system, wherein a sample is arranged between an incident rod and a transmission rod, an incident rod strain gauge and a transmission rod strain gauge are respectively arranged on the incident rod and the transmission rod, and the incident rod strain gauge and the transmission rod strain gauge are both connected with the data acquisition processing system.
Description
Technical Field
The utility model belongs to rock dynamics test field. The utility model relates to a Hopkinson pressure bar experimental device for testing the dynamic mechanical properties and the destructive behaviors of rocks or concrete samples with different sizes.
Background
Impact loading of rocks, concrete or rock mass structures and rock dynamics problems associated therewith are involved in civil engineering such as mining, geotechnical, hydraulic, traffic, civil air defence and natural disasters such as earthquakes, landslides and the like. Therefore, the research and the mastering of the dynamic mechanical properties of materials such as rocks, concrete and the like have very important scientific and engineering practical significance for the design, the stability and the safety evaluation of rock engineering.
The Split Hopkinson Pressure Bar (SHPB) is one of the international standard test devices used to study the dynamic mechanical properties of materials. In recent years, based on the SHPB device, a large number of experimental studies on the dynamic performance of materials such as rocks and concrete have been carried out by domestic and foreign scholars, and a series of results of the studies have been obtained. Because the test of brittle materials such as rock, concrete and the like requires that the size of a test sample is large (usually, the diameter of the test sample is required to be more than 10 times or more than the maximum composition particle size of the test sample), and the brittle materials such as the rock, the concrete and the like have obvious size effect, in order to research the dynamic characteristics of the brittle materials such as the rock, the concrete and the like with different sizes, the traditional method is to simultaneously construct a plurality of sets of Hopkinson pressure bar test systems with different bar diameters. Although the method can meet the test requirement, the manufacturing cost of the SHPB device is high, the occupied area is large, the economic cost is increased by times easily, and the serious waste of the laboratory land resources is easily caused to the scientific research unit with short laboratory land area.
SUMMERY OF THE UTILITY MODEL
The utility model aims at overcoming not enough among the prior art, develop the dynamic impact experiment of brittle materials such as different diameter size rocks, concrete down, research rocks, the dynamic mechanical properties and the destructive behavior of brittle materials such as concrete provide a but variable rod footpath hopkinson pressure bar experimental apparatus, through the three-jaw chuck device in design variable rod footpath, can concentrate on one set of test platform with the hopkinson pressure bar system of different diameters, have apparent economic benefits, scientific research and engineering application meaning.
The utility model aims at realizing through the following technical scheme:
a variable-rod-diameter Hopkinson pressure bar experimental device comprises a three-jaw chuck, a transmitting system, an experimental rod system and a data acquisition and processing system; the launching system consists of an air pump, an air cylinder and a gun barrel, and the experimental rod system consists of an impact rod, an incident rod, a transmission rod and an absorption rod; the incident rod, the transmission rod and the absorption rod are sequentially and centrally clamped by a three-jaw chuck; the three-jaw chuck consists of a baffle, a base, a pneumatic chuck, a radial moving pawl, a roller, a pneumatic adjusting air inlet and a manual adjusting valve; the baffle is fixed on the upper surface of the base, the pneumatic chuck is fixed on one side of the baffle, the radial moving pawls are uniformly distributed on the outer side of the pneumatic chuck, the pneumatic adjusting air inlet and the manual adjusting valve are arranged on the pneumatic chuck, the pneumatic chuck is connected with the air pump through the pneumatic adjusting air inlet, the radial moving pawls can move in the radial direction by adjusting air pressure, and the movement of the radial moving pawls can be controlled by rotating the manual adjusting valve; the roller moves the clamping end of the pawl in the radial direction, and the incident rod, the transmission rod and the absorption rod can slide on the roller;
the impact rod is arranged in the gun barrel and is aligned with the incident end of the incident rod; a sample is arranged between the incident rod and the transmission rod, an incident rod strain gauge and a transmission rod strain gauge are respectively arranged on the incident rod and the transmission rod, and the incident rod strain gauge and the transmission rod strain gauge are both connected with the data acquisition and processing system;
the tail end of the absorption rod is also provided with a damping baffle.
Further, the radial movement adjustment range of the radial moving pawl is 25mm to 100 mm.
Further, the inner diameter of the gun barrel is 80-120 mm.
Further, the outer wall of the impact rod is provided with a Teflon sleeve.
Furthermore, the data acquisition and processing system consists of a super-dynamic strain gauge and an oscilloscope.
Compared with the prior art, the utility model discloses a beneficial effect that technical scheme brought is:
the utility model provides an experimental system can concentrate on one set of test platform with the hopkinson compression bar system of the different diameters of 20-100mm through the three-jaw chuck of self-designed, has overcome current hopkinson compression bar device and can't develop the shortcoming of brittle material dynamic impact experimental study such as not unidimensional rocks, concrete simultaneously, can adopt pneumatic or manual mode fine setting radial movement pawl realization system's accurate centering simultaneously to reduce experimental error. The experimental system saves the field, is convenient to install, is economical and efficient, meets the requirements and regulations of rock dynamic tests, and has obvious scientific research and engineering application significance.
Drawings
Fig. 1 is a schematic structural diagram of the experimental device of the present invention.
Fig. 2 is a three-dimensional structure diagram of the three-jaw chuck.
Fig. 3-1 to 3-3 are schematic front, side and top views of a three-jaw chuck, respectively.
FIGS. 4-1 and 4-2 are schematic views of the installation state of the rod members of the experimental rod system with diameters of 100mm and 38mm, respectively.
FIG. 5 is a schematic view of the construction of a 38mm diameter striker bar.
Reference numerals: 1-air pump, 2-air cylinder, 3-barrel, 4-impact rod, 5-incident rod, 6-three-jaw chuck, 7-incident rod strain gauge, 8-sample, 9-transmission rod, 10-transmission rod strain gauge, 11-absorption rod, 12-damping baffle, 13-ultra dynamic strain gauge, 14-oscilloscope, 15-baffle, 16-pneumatic chuck, 17-roller, 18-radial moving pawl, 19-base, 20-manual regulating valve, 21-pneumatic regulating air inlet, 22-38mm impact rod and 23-Teflon sleeve.
Detailed Description
The present invention will be described in further detail with reference to the following drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1 to 5, the utility model relates to a variable rod diameter hopkinson pressure bar experimental device, which comprises a three-jaw chuck 6, a transmitting system, an experimental rod system and a data acquisition and processing system; the launching system consists of an air pump 1, an air cylinder 2 and a gun barrel 3, and the experimental rod system consists of a striking rod 4, an incident rod 5, a transmission rod 9 and an absorption rod 11; the incident rod 5, the transmission rod 9 and the absorption rod 11 are sequentially and centrally clamped by the three-jaw chuck 6; the three-jaw chuck consists of a baffle 15, a base 19, a pneumatic chuck 16, a radial moving pawl 18, a roller 17, a pneumatic adjusting air inlet 21 and a manual adjusting valve 20; the baffle 15 is fixed on the upper surface of the base 19, the air chuck 16 is fixed on one side of the baffle 15, the radial moving pawls 18 are uniformly distributed on the outer side of the air chuck 16, the pneumatic adjusting air inlet 21 and the manual adjusting valve 20 are arranged on the air chuck 16, the air chuck 16 is connected with the air pump 1 through the pneumatic adjusting air inlet 21, the radial moving pawls 18 can move in the radial direction by adjusting air pressure, the movement of the radial moving pawls 18 can be controlled by rotating the manual adjusting valve 20, and the adjusting range is 25mm to 100 mm; the roller 17 moves the grip end of the ratchet 18 each radially, and the incident rod 5, the transmission rod 9 and the absorption rod 11 can slide on the roller 17;
the impact rod 4 is arranged in the barrel 3 and is aligned with the incident end of the incident rod 5; a sample 8 is arranged between the incident rod 5 and the transmission rod 9, an incident rod strain gauge 7 and a transmission rod strain gauge 10 are respectively arranged on the incident rod 5 and the transmission rod 9, and the incident rod strain gauge 7 and the transmission rod strain gauge 10 are both connected with a super-dynamic strain gauge 13 and an oscilloscope 14; the end of the absorption bar 11 is also provided with a damping baffle 12.
When an experimental rod with a diameter less than 100mm, such as a striker rod 22 with a diameter of 38mm, a teflon sleeve 23 with an outer diameter of 100mm can be added on the periphery of the striker rod to ensure that the striker rod can smoothly move in the barrel and ensure the centering impact with the incident rod. Through the experiment pole system of changing different diameters of 25mm to 100mm, can the utility model discloses a develop the dynamic impact experimental study of brittle materials such as rock, concrete under the different diameter sizes on the same set of Hopkinson pressure bar experiment platform.
During the experiment, the compressed gas in the launching system pushes the impact rod 4 to impact the incident rod 5 to generate incident stress wavesI(t) and propagates in the direction of the transmission rod 9. When the incident stress wave is transmitted to the interface of the incident rod 5 and the sample 8, the incident stress wave is transmitted and reflected, and a part of the incident stress wave is reflected to the incident rod to form a reflected tensile waveR(t) and propagating along the direction far away from the transmission rod, and transmitting the residual incident stress wave to the transmission rod through the test sample to form a transmission stress waveT(t), continues to propagate forward and be absorbed by the absorption rod. Incident and reflected stress wave signals may be measured by the incident rod strain gage 7 and transmitted stress wave signals may be measured by the transmitted rod strain gage 10. The incident rod strain gauge 7 and the transmission rod strain gauge 10 are connected with the ultra-dynamic strain gauge 13 and the oscilloscope 14, so that stress wave signals monitored on the experimental rod are collected and stored. The energy of the test rod after the impact is completed will be absorbed by the impact of the absorber rod 11 against the baffle 12.
Based on the one-dimensional stress wave theory, according to the data monitored in the test process, the dynamic strength sigma (t), the dynamic strain (t) and the dynamic loading strain rate of the sample
The calculation is as follows:
in the formula:I(t)、R(t) andT(t) represents the monitored incident, reflected and transmitted strain signals, respectively; A. e and C respectively represent the cross-sectional area, the elastic modulus and the longitudinal wave velocity of the experimental rod; a. thesAnd LSRespectively representing the cross-sectional area and the length of the sample; t represents the duration of the stress wave.
Since both the test specimen end and the test rod end are sufficiently lubricated by a lubricant (e.g., petrolatum) during testing, the dissipation of the ability at the test rod to specimen interface due to friction is negligible and, therefore, the dissipated energy E during testingSCan be measured by incident stress wave energy EIReflected stress wave energy ERAnd transmitted stress wave energy ETAs determined, it is defined as follows:
ES＝EI-ER-ET(6)
in the formula: ρ represents the density of the experimental bar.
Best embodiment 1:
step 1: an incident rod 5, a transmission rod 9 and an absorption rod 11 which are made of high-strength silicon manganese steel and have the diameter of 100mm and the lengths of 4000mm, 4000mm and 1000mm are arranged in a three-jaw chuck 6, and proper intervals, such as 800mm, are kept among the three-jaw chuck 6 so as to reduce the influence of the dead weight of an experimental rod on the experiment;
step 2: the three-jaw chuck 6 is radially adjusted through a pneumatic device (or a manual adjusting valve 20), so that the incident rod 5, the transmission rod 9 and the absorption rod 11 are positioned on the same axis and can smoothly slide;
and step 3: an incident rod strain gauge 7 and a transmission rod strain gauge 10 are adhered to the central positions of the incident rod 5 and the transmission rod 9 and are connected with a super-dynamic strain gauge 13 and an oscilloscope 14, and the smooth circuit is ensured;
and 4, step 4: after the step 3 is finished, performing a blank impact test without installing a test sample to check the feasibility and reliability of the experimental system (namely, calibrating the system);
and 5: after the operation of the step 4 is finished, two ends of the sample 8 which is polished and measured in size are fully lubricated by lubricating oil and then clamped between the incident rod 5 and the transmission rod 9, and the axis of the sample 8 is superposed with the axes of the incident rod 5 and the transmission rod 9;
step 6: after the step 5 is finished, selecting proper impact air pressure to carry out an impact experiment according to the design of the test experiment, wherein data measured by the experiment (an incident strain signal and a reflected strain signal monitored by an incident rod strain gage 7 and a transmitted strain signal monitored by a transmission rod strain gage 10) need to be completely recorded in the experiment;
and 7: and (3) calculating and analyzing the dynamic mechanical characteristics and the failure behaviors of the test sample by using the calculation formulas (1) to (6) based on a one-dimensional stress wave theory and combined with the actually measured data of the test.
Best embodiment 2:
step 1: the incident rod 5, the transmission rod 9 and the absorption rod 11, which are made of high-strength silicon manganese steel and have the diameter of 38mm, the length of 2000mm and the length of 500mm, are arranged in the three-jaw chucks 6, and proper intervals, such as 1000mm, are kept among the three-jaw chucks 6 so as to reduce the influence of the dead weight of the experimental rod on the experiment;
step 2: the three-jaw chuck 6 is radially adjusted through a pneumatic device (or a manual adjusting valve 20), so that the incident rod 5, the transmission rod 9 and the absorption rod 11 are positioned on the same axis and can smoothly slide;
and step 3: an incident rod strain gauge 7 and a transmission rod strain gauge 10 are adhered to the central positions of the incident rod 5 and the transmission rod 9 and are connected with a super-dynamic strain gauge 13 and an oscilloscope 14, and the smooth circuit is ensured;
and 4, step 4: after the step 3 is finished, performing a blank impact test without installing a test sample to check the feasibility and reliability of the experimental system (namely, calibrating the system);
and 5: after the step 4 is finished, two ends of the sample 8 which is polished and measured in size are fully lubricated by lubricating oil and then clamped between the incident rod 5 and the transmission rod 9, and the axis of the sample 8 is superposed with the axes of the incident rod 5 and the transmission rod 9;
step 6: after the step 5 is finished, selecting proper impact air pressure to carry out an impact experiment according to the design of the test experiment, wherein data measured by the experiment (an incident strain signal and a reflected strain signal monitored by an incident rod strain gage 7 and a transmitted strain signal monitored by a transmission rod strain gage 10) need to be completely recorded in the experiment;
and 7: and (3) calculating and analyzing the dynamic mechanical characteristics and the failure behaviors of the test sample by using the calculation formulas (1) to (6) based on a one-dimensional stress wave theory and combined with the actually measured data of the test.
The present invention is not limited to the above-described embodiments. The above description of the embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above embodiments are merely illustrative and not restrictive. Without departing from the spirit of the invention and the scope of the appended claims, the person skilled in the art can make many changes in form and detail within the teaching of the invention.
Claims (5)
1. A variable-rod-diameter Hopkinson pressure bar experimental device is characterized by comprising a three-jaw chuck (6), a transmitting system, an experimental rod system and a data acquisition and processing system; the launching system consists of an air pump (1), an air cylinder (2) and a gun barrel (3), and the experimental rod system consists of a striking rod (4), an incident rod (5), a transmission rod (9) and an absorption rod (11); the incident rod (5), the transmission rod (9) and the absorption rod (11) are sequentially and centrally clamped through a three-jaw chuck (6); the three-jaw chuck consists of a baffle plate (15), a base (19), a pneumatic chuck (16), a radial moving pawl (18), a roller (17), a pneumatic adjusting air inlet (21) and a manual adjusting valve (20); the baffle (15) is fixed on the upper surface of the base (19), the pneumatic chuck (16) is fixed on one side of the baffle (15), the radial moving pawls (18) are uniformly distributed on the outer side of the pneumatic chuck (16), the pneumatic adjusting air inlet (21) and the manual adjusting valve (20) are arranged on the pneumatic chuck (16), the pneumatic chuck (16) is connected with the air pump (1) through the pneumatic adjusting air inlet (21), the radial moving pawls (18) can move in the radial direction by adjusting air pressure, and the movement of the radial moving pawls (18) can be controlled by rotating the manual adjusting valve (20); the roller (17) moves the clamping end of the pawl (18) in each radial direction, and the incident rod (5), the transmission rod (9) and the absorption rod (11) can slide on the roller (17);
the impact rod (4) is arranged in the gun barrel (3) and is aligned with the incident end of the incident rod (5); a sample (8) is arranged between the incident rod (5) and the transmission rod (9), an incident rod strain gauge (7) and a transmission rod strain gauge (10) are respectively arranged on the incident rod (5) and the transmission rod (9), and the incident rod strain gauge (7) and the transmission rod strain gauge (10) are both connected with the data acquisition and processing system;
the tail end of the absorption rod (11) is also provided with a damping baffle plate (12).
2. The variable-rod-diameter Hopkinson pressure bar experiment device according to claim 1, wherein the radial motion adjustment range of said radially moving pawl (18) is 25mm to 100 mm.
3. The variable-rod-diameter Hopkinson pressure bar experimental device according to claim 1, wherein the inner diameter of the gun barrel (3) is 80-120 mm.
4. The variable-rod-diameter Hopkinson pressure bar experimental device according to claim 1, wherein a Teflon sleeve (23) is arranged on the outer wall of the impact rod (4).
5. The variable-rod-diameter Hopkinson pressure bar experimental device according to claim 1, wherein the data acquisition and processing system is composed of a hyper-dynamic strain gauge (13) and an oscilloscope (14).
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| CN110579413A (en) * | 2019-06-28 | 2019-12-17 | 天津大学 | variable-rod-diameter Hopkinson pressure bar experiment device and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110579413A (en) * | 2019-06-28 | 2019-12-17 | 天津大学 | variable-rod-diameter Hopkinson pressure bar experiment device and method |
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