CN211122369U - A variable rod diameter Hopkinson pressure rod experimental device - Google Patents

Abstract

The utility model discloses a variable rod diameter Hopkinson pressure rod experimental device. The device comprises a three-jaw chuck, a launching system, an experimental rod system and a data acquisition and processing system; the launching system is composed of an air pump, a cylinder and a gun barrel. The system is composed 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 centered and clamped in turn by the three-jaw chuck; the three-jaw chuck is composed of a baffle, a base, a pneumatic chuck, It is composed of radial moving pawl, roller, pneumatic adjustment air inlet and manual adjustment valve; the pneumatic chuck is connected with the air pump through the pneumatic adjustment air inlet; the clamping end of each radially moving pawl of the roller, the incident rod, the transmission The rod and the absorption rod can slide on the roller; the sample is arranged between the incident rod and the transmission rod, and the incident rod and the transmission rod are respectively provided with the incident rod strain gauge and the transmission rod strain gauge, the incident rod strain gauge and the transmission rod The strain gauges are all connected with the data acquisition and processing system.

Description

A variable rod diameter Hopkinson pressure rod experimental device

technical field

The utility model belongs to the field of rock dynamics testing. The utility model relates to a Hopkinson compression bar experimental device for testing the dynamic mechanical properties and failure behavior of rock or concrete samples of different sizes.

Background technique

In civil engineering such as mining, geotechnical, water conservancy, transportation, civil air defense, as well as natural disasters such as earthquakes and landslides, rock, concrete or rock mass structures are affected by impact loads and related rock dynamics problems. Therefore, it is of great scientific and engineering practical significance to study and master the dynamic mechanical properties of materials such as rock and concrete for the design, stability and safety assessment of rock mass engineering.

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, domestic and foreign scholars have carried out a large number of experimental studies on the dynamic properties of materials such as rock and concrete, and have achieved a series of research results. Since the test of brittle materials such as rock and concrete requires a larger size of the test sample (usually the diameter of the sample is required to be 10 times or more than the maximum particle size of the sample), and brittle materials such as rock and concrete have obvious size effects, therefore, In order to study the dynamic properties of brittle materials such as rocks and concrete of different sizes, the traditional method is to construct several sets of Hopkinson compression bar test systems with different bar diameters at the same time. Although this method can meet the testing needs, however, due to the high cost and large area of the SHPB device, it is easy to double the economic cost. serious waste.

Utility model content

The purpose of this utility model is to overcome the deficiencies in the prior art, carry out dynamic impact experiments on brittle materials such as rocks and concrete under different diameters, study the dynamic mechanical properties and failure behaviors of brittle materials such as rocks and concrete, and provide an The variable rod diameter Hopkinson pressure rod experimental device, by designing a three-jaw chuck device with variable rod diameter, can concentrate the Hopkinson pressure rod system of different diameters on a test platform, which has significant economic benefits and scientific Implications for research and engineering applications.

The purpose of this utility model is to realize through the following technical solutions:

A variable rod diameter Hopkinson pressure rod experimental device includes a three-jaw chuck, a launching system, an experimental rod system and a data acquisition and processing system; the launching system consists of an air pump, a cylinder and a gun barrel, and the experimental rod system consists of an impact rod, The incident rod, the transmission rod and the absorption rod are composed of the incident rod, the transmission rod and the absorption rod; It is composed of a moving pawl, a roller, a pneumatic adjustment air inlet and a manual adjustment valve; the baffle is fixed on the upper surface of the base, the pneumatic chuck is fixed on one side of the baffle, and the radially moving pawl is uniform Distributed on the outside of the pneumatic chuck, the pneumatic adjustment air inlet and the manual adjustment valve are arranged on the pneumatic chuck, the pneumatic chuck is connected with the air pump through the pneumatic adjustment air inlet, and the radial movement of the pawl can be made by adjusting the air pressure. The movement of the radially moving pawl can also be controlled by rotating the manual regulating valve; the clamping end of each radially moving pawl of the roller, the incident rod, the transmission rod and the absorption rod can slide on the roller;

The impact rod is arranged in the barrel and is aligned with the incident end of the incident rod; a sample is arranged between the incident rod and the transmission rod, and the incident rod and the transmission rod are respectively provided with an incident rod strain gauge and a transmission rod. The rod strain gauge, the incident rod strain gauge and the transmission rod strain gauge are all connected with the data acquisition and processing system;

The end of the absorption rod is also provided with a damping baffle.

Further, the radial movement adjustment range of the radially moving pawl is 25mm to 100mm.

Further, the inner diameter of the barrel is 80-120 mm.

Further, the outer wall of the impact rod is provided with a Teflon sleeve.

Further, the data acquisition and processing system is composed of an ultra-dynamic strain gauge and an oscilloscope.

Compared with the prior art, the beneficial effects brought by the technical solution of the present utility model are:

The experimental system in the utility model can collect Hopkinson pressure bar systems with different diameters of 20-100 mm on a set of test platforms through a self-designed three-jaw chuck, which overcomes the fact that the existing Hopkinson pressure bar devices cannot be simultaneously developed The shortcomings of dynamic impact experimental research on brittle materials such as rocks and concrete of different sizes, at the same time, the radial moving pawl can be fine-tuned by pneumatic or manual methods to achieve accurate centering of the system, thereby reducing the experimental error. The experimental system saves space, is easy to install, is economical and efficient, meets the requirements and regulations of rock dynamic test, and has significant scientific research and engineering application significance.

Description of drawings

FIG. 1 is a schematic structural diagram of the experimental device of the present invention.

FIG. 2 is a schematic diagram of the three-dimensional structure of the three-jaw chuck.

Figures 3-1 to 3-3 are the front, side and top structural schematic diagrams of the three-jaw chuck, respectively.

Figure 4-1 and Figure 4-2 are the schematic diagrams of the rod installation state of the experimental rod system with a diameter of 100mm and 38mm, respectively.

Figure 5 is a schematic diagram of the structure of a 38mm diameter impact rod.

Reference numerals: 1-air pump, 2-air cylinder, 3-gun barrel, 4-impact rod, 5-incidence rod, 6-three-jaw chuck, 7-incidence rod strain gauge, 8-sample, 9-transmission rod , 10-transmissive rod strain gauge, 11-absorbing rod, 12-damping baffle, 13-super dynamic strain gauge, 14-oscilloscope, 15-baffle, 16-pneumatic chuck, 17-roller, 18-radial movement Pawl, 19- Base, 20- Manual Adjustment Valve, 21- Pneumatic Adjustment Air Inlet, 22-38mm Striker Bar, 23- Teflon Sleeve.

Detailed ways

The present utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention.

As shown in Figures 1 to 5, a variable rod diameter Hopkinson pressure rod experimental device involved in the present invention includes a three-jaw chuck 6, a launching system, an experimental rod system and a data acquisition and processing system; the launching system consists of The air pump 1, the cylinder 2 and the barrel 3 are composed. The experimental rod system is composed of the impact rod 4, the incident rod 5, the transmission rod 9 and the absorption rod 11; Centering clamping setting; three-jaw chuck consists of baffle 15, base 19, pneumatic chuck 16, radially moving pawl 18, roller 17, pneumatic adjustment air inlet 21 and manual adjustment valve 20; baffle 15 Fixed on the upper surface of the base 19, the pneumatic chuck 16 is fixed on one side of the baffle 15, the radially moving pawls 18 are evenly distributed on the outer side of the pneumatic chuck 16, the pneumatic adjustment air inlet 21 and the manual adjustment valve 20 are arranged at On the pneumatic chuck 16, the pneumatic chuck 16 is connected to the air pump 1 through the pneumatic adjustment air inlet 21. The radial moving pawl 18 can be moved radially by adjusting the air pressure, and the radial direction can also be controlled by rotating the manual adjustment valve 20. The movement of the moving pawl 18 has an adjustment range of 25mm to 100mm; each of the rollers 17 radially moves the clamping end of the pawl 18, 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; the incident rod 5 and the transmission rod 9 are provided with a sample 8, and the incident rod 5 and the transmission rod 9 are respectively provided with an incident rod The strain gauge 7 and the transmission rod strain gauge 10, the incident rod strain gauge 7 and the transmission rod strain gauge 10 are connected to the hyperdynamic strain gauge 13 and the oscilloscope 14; the end of the absorption rod 11 is also provided with a damping baffle 12.

When using an experimental rod with a diameter of less than 100mm, such as the impact rod 22 with a diameter of 38mm, a Teflon sleeve 23 with an outer diameter of 100mm can be added to the periphery of the impact rod to ensure that the impact rod can move smoothly in the barrel, and ensure that the impact rod can move smoothly in the barrel. Concentric impact of the incident rod. By replacing the experimental rod system with different diameters from 25mm to 100mm, the dynamic impact experimental research of rock, concrete and other brittle materials with different diameters can be carried out on the same set of Hopkinson pressure rod experimental platform of the utility model patent.

During the experiment, the compressed gas in the launching system pushes the impact rod 4 to hit the incident rod 5 to generate an incident stress wave ε _I (t) and propagates toward the transmission rod 9 . When the incident stress wave is transmitted to the interface between the incident rod 5 and the sample 8, transmission and reflection will occur, and a part of the incident stress wave is reflected into the incident rod to form a reflected tensile wave ε _R (t), which propagates in the direction away from the transmission rod, and the remaining incident stress The wave passes through the test specimen to the transmission rod as the transmitted stress wave ε _T (t), which continues to propagate forward and is absorbed by the absorption rod. The incident and reflected stress wave signals can be measured by the incident rod strain gauge 7 , and the transmitted stress wave signal can be measured by the transmission rod strain gauge 10 . The incident rod strain gauge 7 and the transmission rod strain gauge 10 are connected to the hyperdynamic strain gauge 13 and the oscilloscope 14 to collect and store the stress wave signal monitored on the experimental rod. After the impact is completed, the energy of the experimental rod will be absorbed by the impact of the absorbing rod 11 on the baffle 12.

计算如下：Based on the one-dimensional stress wave theory, according to the data monitored during the testing process, the dynamic strength σ(t), dynamic strain ε(t) and dynamic loading strain rate of the specimen

The calculation is as follows:

where ε _I (t), ε _R (t) and ε _T (t) represent the monitored incident, reflected and transmitted strain signals, respectively; A, E and C represent the cross-sectional area, elastic modulus and The longitudinal wave velocity; A _s and L _S represent the cross-sectional area and length of the specimen, respectively; t represents the duration of the stress wave.

Since the end of the test sample and the end of the test rod are fully lubricated by lubricant (such as Vaseline) during the test, the energy dissipation caused by friction at the interface between the test rod and the test sample can be ignored. The scattered energy ES can be determined by the incident stress wave energy _{E I} , the reflected stress wave energy E _R and the transmitted stress wave energy E _T , which are defined as follows:

E _S =E _I -E _R -E _T (6)

In the formula: ρ represents the density of the experimental rod.

Best practice 1:

Step 1: Place the incident rod 5, transmission rod 9 and absorption rod 11 made of high-strength silicon-manganese steel with a diameter of 100 mm and a length of 4000 mm, 4000 mm and 1000 mm respectively in the three-jaw chuck 6. Keep an appropriate interval, such as 800mm, to reduce the influence of the weight of the test rod on the experiment;

Step 2: radially adjust the three-jaw chuck 6 through the pneumatic device (or the manual adjustment valve 20), so that the incident rod 5, the transmission rod 9 and the absorption rod 11 are on the same axis and can slide smoothly;

Step 3: Paste the incident rod strain gauge 7 and the transmission rod strain gauge 10 at the central positions of the incident rod 5 and the transmission rod 9, and connect them to the hyperdynamic strain gauge 13 and the oscilloscope 14, and ensure that the circuit is unobstructed;

Step 4: After the above-mentioned step 3 is completed, carry out an air shock test without installing the test sample to check the feasibility and reliability of the experimental system (that is, the calibration system);

Step 5: After the operation of step 4 is completed, both ends of the polished and measured sample 8 are fully lubricated with lubricating oil and then sandwiched between the incident rod 5 and the transmission rod 9, and the axis of the sample 8 is The axes of the incident rod 5 and the transmission rod 9 are coincident;

Step 6: After the above step 5 is completed, according to the test design, select the appropriate impact pressure to carry out the impact test. During the test, it is necessary to completely record the data measured in the experiment (the incident strain signal and the reflected strain monitored by the incident rod strain gauge 7). signal, the transmission strain signal monitored by the transmission rod strain gauge 10);

Step 7: Calculate and analyze the dynamic mechanical properties and failure behavior of the test sample by using the calculation formulas (1) to (6) based on the one-dimensional stress wave theory and in combination with the test data.

Best practice 2:

Step 1: Place the incident rod 5, transmission rod 9 and absorption rod 11 made of high-strength silicon-manganese steel with a diameter of 38mm, lengths of 2000mm, 2000mm and 500mm in the three-jaw chuck 6, and the three-jaw chuck 6 is kept between Appropriate interval, such as 1000 mm, to reduce the influence of the weight of the test rod on the experiment;

Step 2: radially adjust the three-jaw chuck 6 through the pneumatic device (or the manual adjustment valve 20), so that the incident rod 5, the transmission rod 9 and the absorption rod 11 are on the same axis and can slide smoothly;

Step 3: Paste the incident rod strain gauge 7 and the transmission rod strain gauge 10 at the central positions of the incident rod 5 and the transmission rod 9, and connect them to the hyperdynamic strain gauge 13 and the oscilloscope 14, and ensure that the circuit is unobstructed;

Step 4: After the above-mentioned step 3 is completed, carry out an air shock test without installing the test sample to check the feasibility and reliability of the experimental system (that is, the calibration system);

Step 5: After the above step 4 is completed, the two ends of the polished and measured sample 8 are fully lubricated with lubricating oil and then sandwiched between the incident rod 5 and the transmission rod 9, and the axis of the sample 8 is connected to the incident rod. The axes of rod 5 and transmission rod 9 coincide;

Step 6: After the above step 5 is completed, according to the test design, select the appropriate impact pressure to carry out the impact test. During the test, it is necessary to completely record the data measured in the experiment (the incident strain signal and the reflected strain monitored by the incident rod strain gauge 7). signal, the transmission strain signal monitored by the transmission rod strain gauge 10);

Step 7: Calculate and analyze the dynamic mechanical properties and failure behavior of the test sample by using the calculation formulas (1) to (6) based on the one-dimensional stress wave theory and in combination with the test data.

The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above-mentioned specific embodiments are only illustrative and not restrictive. Without departing from the scope of protection of the purpose of the present invention and the claims, those of ordinary skill in the art can also make many specific transformations under the inspiration of the present invention, which all belong to the protection scope of the present invention. Inside.

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).

Images