A small adjustable low-temperature environment generation chamber for high strain rate testing and its use method

Abstract

The present invention discloses a small, adjustable low-temperature environment generation chamber for high-strain rate testing, comprising a main chamber, a first cover plate, a second cover plate, a temperature-measuring thermocouple, a temperature controller, an observation window, and a base. The main chamber is clamped to the first and second cover plates at both ends, and the base is mounted on the bottom. The main chamber is provided with a test chamber, a refrigeration chamber, and a heat-insulating chamber, arranged in sequence from the inside to the outside of the central axis. Each chamber is provided with an observation window. One end of a one-dimensional stress wave incident loading rod and one end of a one-dimensional stress wave transmission loading rod are respectively passed through the main chamber from the outside of the first and second cover plates to the test chamber. A temperature-measuring thermocouple is provided in the test chamber. The temperature controller is arranged outside the main chamber and is connected to the temperature-measuring thermocouple signal. A method for using the chamber is also disclosed. The present invention can provide a stable ambient temperature for a test piece that has undergone a cooling treatment during the experiment, avoiding the problem of temperature loss during the test piece replacement process. The chamber has the advantages of simple structure, detachability, portability, and easy operation.

Description

Technical Field

[0001] The invention relates to an experimental device for testing the dynamic mechanical properties of materials, in particular to a small adjustable low-temperature environment generating chamber for high strain rate testing and a use method thereof. Background Art

[0002] High strain rate one-dimensional tension and compression performance testing device is widely used in the field of material dynamic mechanical properties testing. It uses the stress wave generated by high-speed impact to make the material produce high-speed deformation and thus measure the dynamic mechanical properties of the material. High strain rate one-dimensional tension and compression performance testing device can measure the dynamic mechanical properties of engineering materials in 10 2 ~10 4 s -1 The stress-strain relationship within the strain rate loading range is convenient, fast, simple in structure, and easy to process waveforms.

[0003] With the development of superconductors, aviation, and materials, engineering materials often need to work in extreme environments of low temperature and high strain rate. High strain rate one-dimensional tensile and compressive performance testing devices are also used to test the dynamic mechanical properties of materials in low temperature environments. At present, the main approach to low temperature dynamic testing is to pre-cool the engineering materials. This is done by placing the engineering materials in a low temperature environment to cool them down in advance, using a thermistor or thermocouple to measure whether the temperature has reached the predetermined temperature, and then transferring the pre-cooled materials to a split Hopkinson pressure bar for testing. However, the high sensitivity of high strain rate one-dimensional tensile and compressive performance testing devices and engineering materials to temperature, as well as the temperature loss when transferring the pre-cooled materials, will have a significant impact on the dynamic mechanical properties testing of materials in low temperature environments, resulting in large experimental errors.

[0004] A currently known low-temperature environmental chamber for a split-type Hopkinson pressure bar (CN113484159B) utilizes a low-temperature test chamber to provide a low ambient temperature, solving the problem of temperature loss during dynamic experiments in low-temperature environments. However, the refrigeration circuit is installed within the experimental chamber, resulting in a long cooling time during the experiment. The ambient temperature of the rear chamber of the low-temperature environmental chamber after refrigeration and insulation is not equal to the ambient temperature of the front chamber, and the entire chamber is refrigerated unevenly. Cooling the sample through a liquid nitrogen spray pipe causes the sample to be placed in a humid environment, resulting in experimental errors. The sample is loaded into a support structure, and although there is an observation window, the condition of the sample cannot be observed during the actual experiment. The low-temperature environmental chamber includes a chamber, a sample conveying device, a fixture, and refrigeration system connecting pipes, resulting in a complex structure and difficult maintenance. The currently known low-temperature impact test device for a split-type Hopkinson pressure bar (CN112033827A) uses a test chamber to surround the incident rod and transmission rod of the entire split-type Hopkinson pressure bar device to cool the environment, solving the problem of different sizes caused by different temperatures at both ends of the incident rod and transmission rod. However, low-temperature testing only requires keeping the specimen at a low temperature, and the entire test chamber is too large and the cost is high. Summary of the Invention

[0005] Purpose of the Invention: To address the above-mentioned issues, the present invention aims to provide a small, adjustable low-temperature environment generation chamber for high-strain-rate testing, optimizing its structure, ensuring experimental results, and reducing costs. The present invention also provides a method for using the chamber.

[0006] Technical solution: A small adjustable low-temperature environment generation chamber for high strain rate testing, including a main cabin, a first cover plate, a second cover plate, a temperature measuring thermocouple, a temperature controller, an observation window, and a base. The main cabin is a hollow cylindrical structure and is placed vertically. Its two ends are respectively clamped with the first cover plate and the second cover plate, and the base is installed at the bottom. The interior of the main cabin is surrounded by three chambers from the central axis from the inside to the outside, namely a test chamber, a refrigeration chamber, and a heat preservation chamber. Each chamber is provided with an observation window. One end of a one-dimensional stress wave incident loading rod and one end of a one-dimensional stress wave transmission loading rod are respectively passed through the main cabin from the outside of the first cover plate and the second cover plate to the test chamber. A temperature measuring thermocouple is provided in the test chamber. The temperature controller is arranged outside the main cabin and connected to the temperature measuring thermocouple signal.

[0007] Furthermore, the main cabin includes an inner ring cover plate 1, an inner ring cover plate 2, and an inner ring plate, an intermediate ring plate, and an outer ring plate, which are spaced apart from the inside to the outside and have flush end faces. The inner ring cover plate 1 and the inner ring cover plate 2 are respectively fixed to the two end faces formed by the three. The interior of the inner ring plate is a test cavity, the space between the inner ring plate and the intermediate ring plate is a refrigeration cavity, and the space between the intermediate ring plate and the outer ring plate is an insulation cavity. A refrigerant injection port is provided on the inner ring cover plate 1, and the refrigerant injection port is connected to the refrigeration cavity. The refrigerant introduced into the refrigeration cavity through the refrigerant injection port is liquid nitrogen, and the insulation cavity is a vacuum environment.

[0008] Preferably, an observation window is installed on each of the inner annular plate, the middle annular plate, and the outer annular plate, and the three observation windows are opposite to each other in sequence.

[0009] The best observation window is a highly transparent double-layer glass observation window. Both layers of glass are curved glass, and there is a vacuum between the two.

[0010] Furthermore, the surface of the inner annular plate is a wavy structure, and its material is copper. The inner ring cover plate 1, the inner ring cover plate 2, the middle annular plate, the outer annular plate, the first cover plate, and the second cover plate are all composite insulation plates.

[0011] Furthermore, the generation cabin also includes female buckles and male buckles. The plate surfaces of the first cover plate and the second cover plate are both conical structures. A plurality of male buckles are installed at intervals on the outer circumferential surfaces of the large ends of the two. A plurality of female buckles are installed on the outer circumferential surfaces of the two ends of the outer annular plate respectively. The first cover plate is arranged on one side of the inner ring cover plate, and the second cover plate is arranged on one side of the inner ring cover plate. The male buckles on the first cover plate and the second cover plate are respectively snapped into correspondence with the female buckles on the outer annular plate. The female buckles and the male buckles are both made of polyhexamethylene adipamide and modified ABS plastic.

[0012] Optimally, a through connection hole is provided on the first cover plate, the connection hole is close to the side of the one-dimensional stress wave incident loading rod, the temperature measuring thermocouple connecting wire is inserted into the test cavity through the connection hole, one end of the wire is connected to the temperature measuring thermocouple, and the other end passes through the connection hole and is connected to the temperature controller outside the main cabin.

[0013] Furthermore, an incident rod hole is provided in the middle of the first cover plate, and a transmission rod hole is provided in the middle of the second cover plate. One end of the one-dimensional stress wave incident loading rod is successively passed through the incident rod hole and the inner ring cover plate one, and one end of the one-dimensional stress wave transmission loading rod is successively passed through the transmission rod hole and the inner ring cover plate two, and the incident rod hole and the transmission rod hole are respectively coated with high lubricating oil.

[0014] Preferably, the base is a liftable base, on which an electric telescopic rod is provided, and the telescopic portion of the electric telescopic rod is fixed to the outer peripheral bottom surface of the main cabin body.

[0015] A method for using the above-mentioned small adjustable low-temperature environment generation chamber for high strain rate testing includes the following steps:

[0016] S1: Place the sample in a liquid nitrogen box for pre-cooling;

[0017] S2: Liquid nitrogen is injected into the refrigeration chamber, and the first and second cover plates are connected to the main cabin respectively. The height of the main cabin is adjusted by the base so that the centers of the first and second cover plates are aligned with one end of the one-dimensional stress wave incident loading rod and one end of the one-dimensional stress wave transmission loading rod respectively. The one-dimensional stress wave incident loading rod is passed through the first and second cover plates in sequence, and the main cabin is placed thereon. The ends of the one-dimensional stress wave incident loading rod and the one-dimensional stress wave transmission loading rod are spaced apart and facing each other outside the generation cabin.

[0018] S3: After the sample is pre-cooled, the sample is installed between the one-dimensional stress wave incident loading rod and the one-dimensional stress wave transmission loading rod. The generation chamber is moved so that the one-dimensional stress wave incident loading rod begins to separate from the second cover plate. The generation chamber moves toward the one-dimensional stress wave transmission loading rod. The sample is observed through the observation window. When the sample enters the test cavity and reaches the middle of the observation window, it stops. A temperature measuring thermocouple is inserted into the temperature measuring cavity. When the temperature measuring thermocouple is close to the sample position, it stops. The camera and lighting equipment are installed in front of the observation window parallel to the front.

[0019] S4: Use a thermocouple to measure the ambient temperature around the sample and adjust the ambient temperature to a predetermined value through an external temperature controller;

[0020] S5: After the ambient temperature reaches the predetermined value, a high strain rate one-dimensional tension and compression performance test experiment is performed;

[0021] S6: After the impact is completed, the generation chamber is moved to the side of the loading rod where the one-dimensional stress wave is incident, the sample after the experiment is taken out, and steps S2 to S5 are repeated for multiple repeated experiments.

[0022] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0023] (1) The generation chamber of the present invention is small in size, detachable, and has simple operation steps; the first and second truncated cone-shaped cover plates on both sides are used to gather the inner main chamber body to form a relatively closed space, which can prevent the impact of experimental debris and further improve the cooling efficiency.

[0024] (2) The inner annular plate of the present invention adopts a wave shape, which increases the cooling area, can further shorten the cooling time, and improve the experimental efficiency.

[0025] (3) The bottom of the present invention is equipped with a base with a lifting function, which can adjust the posture of the generation cabin to ensure the coaxiality of the one-dimensional stress wave incident loading rod, the one-dimensional stress wave transmission loading rod and the main cabin;

[0026] (4) The present invention uses a temperature measuring thermocouple and a temperature controller to accurately adjust the ambient temperature within the device.

[0027] (5) The present invention has a highly transparent observation window on the front of the generation cabin, which is conducive to experimental photography and recording. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the three-dimensional structure of the present invention during testing;

[0029] Figure 2 This is a schematic diagram of the internal structure of the main cabin;

[0030] Figure 3 This is a right view of the present invention during a high strain rate one-dimensional tension and compression performance test;

[0031] Figure 4 This is a schematic diagram of the left side cross-section of the present invention during a high strain rate one-dimensional tension and compression performance test;

[0032] Figure 5 This is a schematic diagram of the internal structure of the present invention when performing high strain rate one-dimensional tension and compression performance testing;

[0033] Figure 6 This is a schematic front cross-sectional view of the high strain rate one-dimensional tension and compression performance test of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0035] A small adjustable low temperature environment generation chamber for high strain rate testing, such as Figures 1 to 6 As shown, it includes a main cabin, a first cover plate 1, a second cover plate 2, a temperature measuring thermocouple 6, a temperature controller, an observation window 7, a base 12, a female buckle 17, and a male buckle 18.

[0036] The main cabin has a hollow cylindrical structure and is placed vertically. The interior of the main cabin is surrounded by three chambers: a test chamber, a refrigeration chamber, and an insulation chamber. The main cabin includes an inner ring cover plate 13, an inner ring cover plate 14, and an inner ring plate 11, an intermediate ring plate 10, and an outer ring plate 9, which are spaced apart from each other and have flush end faces from the inside to the outside. The inner ring cover plate 13 and the inner ring cover plate 14 are respectively fixed to the two end faces formed by the three. The surface of the inner ring plate 11 is a wavy structure. Its material is copper with good thermal conductivity. The inner ring cover plate 13, the inner ring cover plate 14, the intermediate ring plate 10, the outer ring plate 9, the first cover plate 1, and the second cover plate 2 are all composite insulation plates.

[0037] The inside of the inner annular plate 11 is a test cavity, the space between the inner annular plate 11 and the middle annular plate 10 is a refrigeration cavity, the space between the middle annular plate 10 and the outer annular plate 9 is an insulation cavity, and a refrigerant injection port 8 is provided on the inner ring cover 13. The refrigerant injection port 8 is connected to the refrigeration cavity, and the refrigerant introduced into the refrigeration cavity through the refrigerant injection port 8 is liquid nitrogen, and the insulation cavity is a vacuum environment.

[0038] An observation window 7 is installed on the inner annular plate 11, the middle annular plate 10 and the outer annular plate 9 respectively. The three observation windows 7 are opposite to each other in sequence. The observation windows 7 are highly transparent double-layer glass observation windows. The double-layer glass is curved glass, and there is a vacuum between the two.

[0039] The two ends of the main cabin are respectively connected with the first cover plate 1 and the second cover plate 2. The plate surfaces of the first cover plate 1 and the second cover plate 2 are both conical structures. A plurality of male buckles 18 are installed at intervals on the outer circumferences of the large ends of the two. A plurality of female buckles 17 are respectively installed on the outer circumferences of the two ends of the outer annular plate 9. The first cover plate 1 is arranged on one side of the inner ring cover plate 13, and the second cover plate 2 is arranged on one side of the inner ring cover plate 2 14. The male buckles 18 on the first cover plate 1 and the second cover plate 2 are respectively connected with the female buckles 17 on the outer annular plate 9. The female buckles 17 and the male buckles 18 are made of polyhexamethylene adipamide and modified ABS plastic and have good flexibility.

[0040] A base 12 is installed at the bottom of the main cabin. The base 12 is a liftable base, on which an electric telescopic rod is provided. The telescopic part of the electric telescopic rod is fixed to the outer bottom surface of the main cabin.

[0041] One end of the one-dimensional stress wave incident loading rod 3 and one end of the one-dimensional stress wave transmission loading rod 4 are respectively passed through the outside of the first cover plate 1 and the second cover plate 2 through the main cabin to the test cavity. A temperature measuring thermocouple 6 is provided in the test cavity. The temperature controller is arranged outside the main cabin and is connected to the temperature measuring thermocouple 6 signal for measuring and changing the ambient temperature.

[0042] A through connection hole 5 is provided on the first cover plate 1 , one end of the wire is connected to the temperature measuring thermocouple 6 , and the other end passes through the connection hole 5 and is connected to the temperature controller outside the main cabin.

[0043] An incident rod hole 15 is provided in the middle of the first cover plate 1, and a transmission rod hole 16 is provided in the middle of the second cover plate 2. One end of the one-dimensional stress wave incident loading rod 3 is sequentially inserted into the incident rod hole 15 and the inner ring cover plate 1 13, and one end of the one-dimensional stress wave transmission loading rod 4 is sequentially inserted into the transmission rod hole 16 and the inner ring cover plate 2 14. The incident rod hole 15 and the transmission rod hole 16 are respectively coated with high lubricating oil.

[0044] The method for using the high strain rate test small adjustable low temperature environment generation chamber comprises the following steps:

[0045] S1: Before the experiment, the sample was placed in a liquid nitrogen box for pre-cooling;

[0046] S2: Inject liquid nitrogen into the refrigeration cavity through the refrigerant injection hole 8, install the first cover plate 1 and the second cover plate 2 on the main cabin, so that the male buckle 18 and the female buckle 17 are correspondingly locked, and adjust the height of the main cabin through the base 12 so that the incident rod hole 15 and the transmission rod hole 16 are aligned with one end of the one-dimensional stress wave incident loading rod 3 and one end of the one-dimensional stress wave transmission loading rod 4 respectively. Pass the one-dimensional stress wave incident loading rod 3 through the first cover plate 1, the main cabin, and the second cover plate 2 in sequence, so that the main cabin is placed thereon, and the ends of the one-dimensional stress wave incident loading rod 3 and the one-dimensional stress wave transmission loading rod 4 are spaced apart and opposite each other outside the generation cabin;

[0047] S3: After the sample is pre-cooled, the sample is installed between the one-dimensional stress wave incident loading rod 3 and the one-dimensional stress wave transmission loading rod 4. The generation chamber is moved so that the one-dimensional stress wave incident loading rod 3 begins to separate from the second cover plate 2. The generation chamber moves toward the one-dimensional stress wave transmission loading rod 4. The sample is observed through the observation window 7. When the sample enters the temperature measurement cavity and reaches the middle of the observation window, the sample stops. The temperature measuring thermocouple 6 is inserted into the temperature measurement cavity through the connecting hole 5. When the temperature measuring thermocouple 6 is close to the sample position, the sample stops. The camera and lighting equipment are installed in front of the observation window 7 and parallel to the observation window 7.

[0048] S4: Using the temperature measuring thermocouple 6 to measure the ambient temperature around the sample, and adjusting the ambient temperature to a predetermined value through an external temperature controller;

[0049] S5: After the ambient temperature reaches the predetermined value, a high strain rate one-dimensional tension and compression performance test experiment is performed;

[0050] S6: After the impact is completed, the generation chamber is moved to the side of the one-dimensional stress wave incident loading rod 3, the sample after the experiment is taken out, and steps S2 to S5 are repeated to perform multiple repeated experiments.

Claims

1. A small adjustable low temperature environment generation chamber for high strain rate testing, characterized by: The invention comprises a main cabin, a first cover plate (1), a second cover plate (2), a temperature measuring thermocouple (6), a temperature controller, an observation window (7), and a base (12). The main cabin is a hollow columnar structure and is placed vertically. Its two ends are respectively connected to the first cover plate (1) and the second cover plate (2). The base (12) is installed at the bottom. The interior of the main cabin is provided with three chambers, namely, a test chamber, a refrigeration chamber, and a heat preservation chamber, which are arranged around the central axis from the inside to the outside. Each chamber is provided with an observation window (7). One end of a one-dimensional stress wave incident loading rod (3) and one end of a one-dimensional stress wave transmission loading rod (4) are respectively passed through the main cabin from the outside of the first cover plate (1) and the second cover plate (2) to the test chamber. A temperature measuring thermocouple (6) is provided in the test chamber. The temperature controller is arranged outside the main cabin and is connected to the temperature measuring thermocouple (6) signal. The main cabin comprises an inner ring cover plate 1 (13), an inner ring cover plate 2 (14), and an inner ring plate (11), an intermediate ring plate (10), and an outer ring plate (9) which are spaced apart from each other and have flush end faces from the inside to the outside. The inner ring cover plate 1 (13) and the inner ring cover plate 2 (14) are fixed to the two end faces formed by the three, respectively. The interior of the inner ring plate (11) is a test cavity, the space between the inner ring plate (11) and the intermediate ring plate (10) is a refrigeration cavity, and the space between the intermediate ring plate (10) and the outer ring plate (9) is a heat preservation cavity. A refrigerant injection port (8) is provided on the inner ring cover plate 1 (13), and the refrigerant injection port (8) is connected to the refrigeration cavity. The refrigerant introduced into the refrigeration cavity through the refrigerant injection port (8) is liquid nitrogen, and the heat preservation cavity is a vacuum environment. An observation window (7) is installed on each of the inner annular plate (11), the middle annular plate (10), and the outer annular plate (9), and the three observation windows (7) are aligned in sequence; It also includes a female buckle (17) and a male buckle (18). The plate surfaces of the first cover plate (1) and the second cover plate (2) are both truncated cone structures. A plurality of male buckles (18) are installed on the outer peripheral surfaces of the large ends of the two, respectively. A plurality of female buckles (17) are installed on the outer peripheral surfaces of the two ends of the outer annular plate (9). The first cover plate (1) is arranged on one side of the inner annular cover plate (13), and the second cover plate (2) is arranged on one side of the inner annular cover plate (14). The male buckles (18) on the first cover plate (1) and the second cover plate (2) are respectively connected to the female buckles (17) on the outer annular plate (9). The female buckles (17) and the male buckles (18) are made of polyhexamethylene adipamide and modified ABS plastic. The base (12) is a liftable base, on which an electric telescopic rod is provided, and the telescopic portion of the electric telescopic rod is fixed to the outer peripheral bottom surface of the main cabin body.

2. The small adjustable low temperature environment generation chamber for high strain rate testing according to claim 1, characterized in that: The observation window (7) is a highly transparent double-layer glass observation window, both of which are curved glass, with a vacuum between the two.

3. The small adjustable low temperature environment generation chamber for high strain rate testing according to claim 1, characterized in that: The surface of the inner annular plate (11) is a wavy structure and is made of copper. The inner ring cover plate 1 (13), the inner ring cover plate 2 (14), the middle annular plate (10), the outer annular plate (9), the first cover plate (1), and the second cover plate (2) are all composite material insulation plates.

4. The small adjustable low temperature environment generation chamber for high strain rate testing according to claim 1, characterized in that: A through connection hole (5) is provided on the first cover plate (1), and the connection hole (5) is close to the side of the one-dimensional stress wave incident loading rod (3). A temperature measuring thermocouple connecting wire is inserted into the test cavity through the connection hole (5), one end of the wire is connected to the temperature measuring thermocouple (6), and the other end passes through the connection hole (5) and is connected to a temperature controller outside the main cabin.

5. The small adjustable low temperature environment generation chamber for high strain rate testing according to claim 1, characterized in that: An incident rod hole (15) is provided in the middle of the first cover plate (1), and a transmission rod hole (16) is provided in the middle of the second cover plate (2). One end of the one-dimensional stress wave incident loading rod (3) is sequentially inserted into the incident rod hole (15) and the inner ring cover plate 1 (13). One end of the one-dimensional stress wave transmission loading rod (4) is sequentially inserted into the transmission rod hole (16) and the inner ring cover plate 2 (14). High-lubricating oil is applied around the incident rod hole (15) and the transmission rod hole (16).

6. A method for using a small adjustable low temperature environment generating chamber for high strain rate testing according to any one of claims 1 to 5, characterized in that The following steps are involved: S1: Place the sample in a liquid nitrogen box for pre-cooling; S2: Liquid nitrogen is injected into the refrigeration chamber, and the first cover plate (1) and the second cover plate (2) are connected to the main cabin respectively. The height of the main cabin is adjusted by the base (12) so that the centers of the first cover plate (1) and the second cover plate (2) are aligned with one end of the one-dimensional stress wave incident loading rod (3) and one end of the one-dimensional stress wave transmission loading rod (4) respectively. The one-dimensional stress wave incident loading rod (3) is passed through the first cover plate (1) and the second cover plate (2) in sequence, so that the main cabin is placed thereon, and the ends of the one-dimensional stress wave incident loading rod (3) and the one-dimensional stress wave transmission loading rod (4) are spaced apart and opposite to each other outside the generation cabin; S3: After the sample is pre-cooled, the sample is installed between the one-dimensional stress wave incident loading rod (3) and the one-dimensional stress wave transmission loading rod (4). The generation chamber is moved so that the one-dimensional stress wave incident loading rod (3) begins to separate from the second cover plate (2). The generation chamber moves toward the one-dimensional stress wave transmission loading rod (4). The sample is observed through the observation window (7). When the sample enters the test cavity and reaches the middle of the observation window (7), it stops. The temperature measuring thermocouple (6) is inserted into the temperature measuring cavity. When the temperature measuring thermocouple (6) is close to the sample position, it stops. The camera and lighting equipment are installed in front of the observation window (7) in parallel. S4: using a temperature measuring thermocouple (6) to measure the ambient temperature around the sample, and adjusting the ambient temperature to a predetermined value through an external temperature controller; S5: After the ambient temperature reaches the predetermined value, a high strain rate one-dimensional tension and compression performance test experiment is performed; S6: After the impact is completed, the generating chamber is moved to the side of the one-dimensional stress wave incident loading rod (3), the sample after the experiment is taken out, and steps S2 to S5 are repeated to perform multiple repeated experiments.

Images