Device for testing mechanical property of material under ultralow temperature condition and use method of device

Abstract

The invention discloses a device for testing mechanical properties of a material under an ultralow temperature condition and a use method of the device. The testing device comprises a cryostat, a sample testing mechanism, an inflating device and a stretching device, the cryostat comprises a heat insulation container, refrigeration equipment and a sample channel; the sample testing mechanism comprises a supporting rod, a stretching rod, a partition plate, a testing upper flange assembly, a bottom plate, a measuring sensor and a clamp; the inflating device is communicated with the sample channel; and the stretching device is fixedly connected with the testing upper flange assembly. Through the refrigerating machine and the heater, the test piece can be rapidly cooled and rapidly adjusted in temperature, the temperature of the test piece is rapidly adjusted, and the test efficiency can be improved.

Description

Technical Field

[0001] This invention relates to the field of material mechanical property testing technology, specifically to a testing device for the mechanical properties of materials under ultra-low temperature conditions and its usage method. Background Technology

[0002] The cryogenic operating temperatures of cryogenic storage and transportation equipment, large superconducting devices, and cryogenic liquid rockets place special demands on the selection of structural materials. Under cryogenic conditions, the mechanical properties of materials change significantly, primarily manifested as a substantial increase in strength, improved fatigue resistance, and a decrease in toughness. Conducting mechanical tests under cryogenic conditions allows for a more comprehensive understanding of material properties, ensuring their safety and reliability in practical applications.

[0003] Currently, the most common method for measuring the liquid helium temperature range (4K-5K) is liquid helium immersion. However, liquid helium is a strategic resource and therefore expensive, and each test results in significant losses, inevitably leading to substantial resource waste and testing costs. Cooling with refrigerators often requires multiple refrigerators and cannot directly cool to the liquid helium temperature range; it necessitates depressurization and evacuation, followed by further cooling to achieve the desired liquid helium temperature. This results in costly experimental setups and complex operation.

[0004] Therefore, there is a need to provide a new testing device for the mechanical properties of materials under ultra-low temperature conditions. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a testing device for the mechanical properties of materials under ultra-low temperature conditions. This device can test the mechanical properties of materials under liquid helium temperature conditions, and the temperature is adjustable. Furthermore, the measuring device has a simple structure, is easy to operate, and is inexpensive.

[0006] A further technical problem to be solved by the present invention is to provide a method for using the above-mentioned testing device.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A testing device for the mechanical properties of materials under ultra-low temperature conditions, comprising a cryostat, a sample testing mechanism, an inflation device, and a tensile device;

[0009] The cryogenic thermostat includes an insulated container, a refrigeration device, and a sample channel; wherein the sample channel, from top to bottom, includes a high-temperature channel, an upper heat cutoff, an upper heat cutoff flexible support, a low-temperature channel, and a thermostat chamber; the cold head of the refrigeration device is located in the insulated container.

[0010] The sample testing mechanism includes a support rod, a tension rod, a partition, a test upper flange assembly, a base plate, a measuring sensor, and a fixture; wherein the support rod passes through the sample channel and one end of the support rod is connected to the test upper flange assembly, and the other end of the support rod is connected to the base plate; the test piece is placed between the fixtures, the tension rod is connected to the fixtures, the partition is fitted onto the tension rod and is fixedly or slidably connected to the support rod, the partition is located above the constant temperature chamber, and the fixtures and the test piece are located inside the constant temperature chamber;

[0011] The inflation device is connected to the sample channel;

[0012] The tensile device is fixedly connected to the test upper flange assembly.

[0013] The insulated container includes an outer wall, a cold shield, a container cover, and a cold shield cover. The cold shield is fitted inside the outer wall of the container. The cold shield and the cold shield cover form a cold shield space. The cold shield cover and the container cover form an outer wall space. The container cover and the cold shield cover are fixedly connected by a tie rod.

[0014] The refrigeration equipment extends longitudinally through the container cover and the cold shield cover. The cold head of the refrigeration equipment includes a primary cold head and a secondary cold head. The primary cold head is located in the outer wall space, and the secondary cold head is located in the cold shield space. The primary cold head is connected to the cold shield cover through a copper flexible connection.

[0015] Heating elements are installed on the secondary cold head.

[0016] The upper thermal cutoff flexible support of the sample channel is located between the cold screen cover and the upper thermal cutoff. The upper thermal cutoff of the sample channel is connected to the cold screen cover through the upper thermal cutoff copper flexible connector. The constant temperature chamber is connected to the cold head of the refrigeration equipment through the constant temperature chamber copper flexible connector.

[0017] There are multiple partitions, and at least one partition is in close contact with the upper heat cut-off plate during the test.

[0018] Among them, multiple partitions are sequentially fitted onto the tension rod from top to bottom and there is a certain gap between them and the tension rod;

[0019] And / or, at least one partition is slidably connected to the support rod and is capable of sliding along the support rod.

[0020] The partition includes, from top to bottom, a first partition, a second partition, a third partition, and a fourth partition. The second partition is in close contact with the upper heat cut-off, the fourth partition can slide along the support rod, and the second partition is connected to the tension rod through a heat transfer flexible connection.

[0021] The inflation device includes a pressure transmitter, a safety valve, a pressure reducing valve, an inflation pipe, an evacuation port, a helium cylinder, and a switch ball valve; the interface of the inflation pipe leading to the sample channel is located between the upper heat cutoff and the constant temperature chamber.

[0022] The method of using the above-mentioned testing device for the mechanical properties of materials under ultra-low temperature conditions includes the following steps:

[0023] S1: Evacuate the inside of the low-temperature thermostat;

[0024] S2: Install the sample testing mechanism and inflation device;

[0025] S3: Replace the sample channel with helium. Specifically, replenish the sample channel with helium through the filling pipe.

[0026] S4: Turn on the refrigeration equipment, set the control temperature, and fix the temperature of the low-temperature thermostat;

[0027] S5: After the temperature of the low-temperature thermostat stabilizes, the mechanical properties can be tested by applying a load to the test piece using a tensile device.

[0028] The beneficial effects of the device for testing the mechanical properties of materials under ultra-low temperature conditions according to the present invention are as follows:

[0029] (1) The test device of the present invention reduces the heat load from the tension rod and the support rod, and reduces the cooling capacity requirement of the refrigeration unit.

[0030] (2) The testing device of the present invention uses a refrigerator as a cold source, eliminating the need for other low-temperature media to provide a low-temperature environment, and in particular, eliminating the dependence on liquid helium, reducing resource waste and saving testing costs.

[0031] (3) The testing device of the present invention is equipped with a heater on the second-stage cold head of the refrigerator, which can accurately and continuously control the temperature of the sample in the liquid helium temperature range of 4K-5K through the temperature control device.

[0032] (4) The testing device of the present invention has a simple structure, low cost and is easy to use. Attached Figure Description

[0033] Figure 1 This is an overall schematic diagram of a testing device for the mechanical properties of materials under ultra-low temperature conditions according to the present invention.

[0034] Figure 2 This is a schematic diagram of the overall structure of the low-temperature thermostat of the testing device of the present invention;

[0035] Figure 3This is a schematic diagram of the overall sample testing mechanism of the testing device of the present invention.

[0036] In the diagram: 1-Low-temperature thermostat; 2-Sample testing mechanism; 3-Inflation device; 4-Tension device; 11-Container outer wall; 12-Cold shield; 13-Refrigeration equipment; 14-Heating element; 15-Sample channel; 16-Upper heat cutoff copper flexible connection; 17-Constant temperature chamber copper flexible connection; 18-Pull rod; 19-Cold shield cover copper flexible connection; 20-Test piece; 21-Support rod; 22-Tension rod; 23-Partition; 24-Heat transfer flexible connection; 25-Test upper flange assembly; 26-Base plate; 27-Clamp; 28-Measuring sensor; 31-Pressure transmitter; 32-Safety valve; 33-Pressure reducing valve; 34-Inflation device Pipeline; 35-Evacuation port; 36-Helium cylinder; 37-Switch ball valve; 110-Container cover; 120-Cold shield cover; 131-First-stage cold head; 132-Second-stage cold head; 151-High-temperature channel; 152-Upper heat shut-off; 153-Low-temperature channel; 154-Constant temperature chamber; 155-Upper heat shut-off flexible support; 231-First partition; 232-Second partition; 233-Third partition; 234-Fourth partition; 251-Support flange; 252-Welded bellows; 253-Traction flange; 271-Lower clamp; 272-Upper clamp; 281-Extensometer; 282-Temperature sensor. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0038] See Figure 1 A testing device for the mechanical properties of materials under ultra-low temperature conditions, comprising a cryostat 1, a sample testing mechanism 2, an inflation device 3, and a tensile device 4.

[0039] The tensioning device 4 can be any existing tensioning device. Figure 1 It is not shown in detail in the text.

[0040] See Figure 2 The cryogenic thermostat 1 includes an insulated container, a refrigeration device 13, and a sample channel 15.

[0041] See Figure 2The insulated container includes an outer wall 11, a cold shield 12, a container cover 110, and a cold shield cover 120. The cold shield 12 is fitted inside the outer wall 11. The cold shield 12 and the cold shield cover 120 form a cold shield space. The cold shield cover 120 and the container cover 110 form an outer wall space. The container cover 110 and the cold shield cover 120 are fixedly connected by a pull rod 18.

[0042] In this embodiment, both the outer wall 11 of the container and the cold shield 12 are hollow cylindrical structures. The container cover 110 is used to close the outer wall 11 of the container, and the cold shield cover 120 is used to close the cold shield 12.

[0043] See Figure 2 The refrigeration device 13 extends longitudinally through the container cover 110 and the cold shield cover 120. The cold head of the refrigeration device 13 is located in the insulated container. Specifically, the cold head of the refrigeration device 13 includes a primary cold head 131 and a secondary cold head 132. The primary cold head 131 is located in the outer wall space, and the secondary cold head 132 is located in the cold shield space. The primary cold head 131 is connected to the cold shield cover 120 via a copper flexible connector 19. In this embodiment, the refrigeration device 13 is a GM refrigeration unit.

[0044] For an even better option, see [link to previous section]. Figure 2 A heating element 14 is installed on the secondary cold head 132.

[0045] See Figure 2 The sample channel 15 includes, from top to bottom, a high-temperature channel 151, an upper heat cutoff 152, an upper heat cutoff flexible support 155, a low-temperature channel 153, and a constant temperature chamber 154.

[0046] The high-temperature channel 151 is constructed of a corrugated pipe. An upper heat cutoff 152 is located below the high-temperature channel 151. A low-temperature channel 153 lies between the upper heat cutoff 152 and the constant-temperature chamber 154. A flexible upper heat cutoff support 155 for the sample channel 15 is located between the cold screen cover 120 and the upper heat cutoff 152. The upper heat cutoff 152 of the sample channel 15 is connected to the cold screen cover 120 via an upper heat cutoff copper flexible connector 16 to obtain cooling. The constant-temperature chamber 154 is located below the cold screen cover 120 and is connected to the cold head of the refrigeration device 13 via a constant-temperature chamber copper flexible connector 17 to transfer cooling. In this embodiment, the constant-temperature chamber 154 is connected to the second cold head 132 of the refrigeration device 13 via the constant-temperature chamber copper flexible connector 17 to transfer cooling. The constant-temperature chamber 154 is preferably made of high-purity oxygen-free copper.

[0047] The upper heat-stop copper flexible connector 16, due to the high thermal conductivity of copper, can better conduct heat and obtain the cooling capacity of the cold screen cover 120.

[0048] See Figure 3 The sample testing mechanism 2 includes a support rod 21, a tension rod 22, a partition 23, a test upper flange assembly 25, a base plate 26, a measuring sensor 28, and a clamp 27.

[0049] The test flange assembly 25 includes a support flange 251, a welded bellows pipe 252, and a traction flange 253. The support flange 251 is installed and fixed on the container cover plate 110. The tensioning device 4 is connected to the traction flange 253.

[0050] The support rod 21 passes through the sample channel 15 and one end of the support rod 21 is connected to the support flange 251 of the test upper flange assembly 25, while the other end of the support rod 21 is connected to the base plate 26; that is, the base plate 26 is fixed to the support flange 251 by the support rod 21.

[0051] The support rod 21 is preferably made of a material that has high strength and low thermal conductivity at low temperatures, such as titanium alloy or high-temperature alloy. Preferably, three or four support rods are used.

[0052] See Figure 3 The fixture 27 includes a lower fixture 271 and an upper fixture 272. The lower fixture 271 is fixed to the base plate 26, and the upper fixture 272 is connected to the tension rod 22. The workpiece 20 to be tested is placed between the upper fixture 272 and the lower fixture 271.

[0053] In this embodiment, the tension rod 22 is preferably made of materials such as titanium alloy or high-temperature alloy, which have high strength and low thermal conductivity at low temperatures.

[0054] See Figure 3 The partition 23 is fitted onto the tension rod 22 and is fixedly or slidably connected to the support rod 21. The partition 23 is located above the constant temperature chamber 154, and the clamp 27 and the test piece 20 are located within the constant temperature chamber 154. In this embodiment, the partition 23 separates the constant temperature chamber 154 from other parts, thus reducing the loss of cold air from the constant temperature chamber 154. In this embodiment, most of the support rod 21 and the tension rod 22 are located below the upper heat cutoff 152, which reduces the heat load from the tension rod 22 and the support rod 21, thereby reducing the cooling capacity requirement of the refrigeration unit.

[0055] In this embodiment, the partition is preferably made of two mirrored surfaces.

[0056] Preferably, in this embodiment, there are multiple partitions 23, and during testing, at least one partition 23 is in close contact with the upper heat cutoff 152, thus ensuring good heat transfer. More preferably, the partition 23 in contact with the upper heat cutoff 152 is made of high-purity oxygen-free copper.

[0057] More preferably, the plurality of partitions 23 are sequentially fitted onto the tension rod 22 from top to bottom, with a certain gap between them. This avoids affecting the measurement accuracy of the tension rod 22, thereby ensuring the measurement effect.

[0058] More preferably, at least one partition 23 is slidably connected to the support rod 21 and is slidable along the support rod 21.

[0059] See Figure 3 In this embodiment, the partition 23 includes, from top to bottom, a first partition 231, a second partition 232, a third partition 233, and a fourth partition 234. The second partition 232 is in close contact with the upper heat cutoff 152, and the fourth partition 234 is slidable along the support rod 21. The first partition 231, the second partition 232, and the third partition 233 are fixed to the support rod 21, and the fourth partition 234 is slidably connected to the support rod 21.

[0060] More preferably, the second partition 232 is connected to the tension rod 22 via a heat transfer flexible connection 24.

[0061] The measuring sensor 28 in this embodiment includes an extensometer 281 and two temperature sensors 282. The extensometer 281 is clamped and mounted on the workpiece 20 to be measured, and the temperature sensors 282 are respectively mounted on the lower clamp 271 and the upper clamp 272.

[0062] See Figure 1 The inflation device 3 is connected to the sample channel 15.

[0063] Specifically, the inflation device 3 includes a pressure transmitter 31, a safety valve 32, a pressure reducing valve 33, an inflation pipe 34, an evacuation port 35, a helium cylinder 36, and a switch ball valve 37 connected in sequence; the interface of the inflation pipe 34 leading to the sample channel 15 is located between the upper heat cutoff 152 and the constant temperature chamber 154.

[0064] The testing device of the present invention reduces heat transfer from the surrounding environment to the tension rod 22 and the support rod 21 by setting up a constant temperature chamber 154; secondly, the mirror-type partition 23 can reduce radiative heat transfer; and thirdly, some partitions 23 connected to the cold head can also reduce the heat load on these two components. Such multi-faceted design reduces the heat load from the tension rod 22 and the support rod 21, thereby reducing the cooling capacity requirement of the refrigeration unit.

[0065] The method of using the above-mentioned testing device for the mechanical properties of materials under ultra-low temperature conditions includes the following steps:

[0066] S1: Evacuate the interior of the low-temperature thermostat 1;

[0067] S2: Install the sample testing mechanism 2 and the inflation device 3;

[0068] S3: Helium is replaced in the sample channel 15. Specifically, helium is added to the sample channel 15 through the gas filling pipe 34. The gas pressure in the sample channel 15 can be read by the pressure transmitter 31.

[0069] S4: Turn on the refrigeration equipment 13, set the control temperature, and fix the temperature of the low-temperature thermostat 1;

[0070] S5: After the temperature of the low-temperature thermostat 1 stabilizes, the tensile device 4 is used to apply a load to the test piece 20, and the strain value of the test piece 20 is recorded by the extensometer 281.

[0071] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0072] The parts of this invention not described in detail are well-known in the art. The above embodiments are provided merely for the purpose of describing the invention and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within the scope of the invention.

Claims

1. A testing device for the mechanical properties of materials under ultra-low temperature conditions, characterized in that, Includes a cryostat, a sample testing mechanism, an inflation device, and a stretching device; The cryogenic thermostat includes an insulated container, a refrigeration device, and a sample channel; wherein the sample channel, from top to bottom, includes a high-temperature channel, an upper heat cutoff, an upper heat cutoff flexible support, a low-temperature channel, and a thermostat chamber; the cold head of the refrigeration device is located in the insulated container. The sample testing mechanism includes a support rod, a tension rod, a partition, a test upper flange assembly, a base plate, a measuring sensor, and a fixture; wherein the support rod passes through the sample channel and one end of the support rod is connected to the test upper flange assembly, and the other end of the support rod is connected to the base plate; the test piece is placed between the fixtures, the tension rod is connected to the fixtures, the partition is fitted onto the tension rod and is fixedly or slidably connected to the support rod, the partition is located above the constant temperature chamber, and the fixtures and the test piece are located inside the constant temperature chamber; The inflation device is connected to the sample channel; The tensile device is fixedly connected to the test upper flange assembly.

2. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 1, characterized in that, The insulated container includes an outer wall, a cold shield, a container cover, and a cold shield cover. The cold shield is fitted inside the outer wall of the container. The cold shield and the cold shield cover form a cold shield space, and the cold shield cover and the container cover form an outer wall space. The container cover and the cold shield cover are fixedly connected by a tie rod.

3. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 2, characterized in that, The refrigeration equipment extends longitudinally through the container cover and the cold shield cover. The cold head of the refrigeration equipment includes a primary cold head and a secondary cold head. The primary cold head is located in the outer wall space, and the secondary cold head is located in the cold shield space. The primary cold head is connected to the cold shield cover through a copper flexible connection.

4. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 3, characterized in that, Heating elements are installed on the secondary cold head.

5. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 1, characterized in that, The upper thermal cutoff flexible support of the sample channel is located between the cold screen cover and the upper thermal cutoff. The upper thermal cutoff of the sample channel is connected to the cold screen cover through the upper thermal cutoff copper flexible connector. The constant temperature chamber is connected to the cold head of the refrigeration equipment through the constant temperature chamber copper flexible connector.

6. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 1, characterized in that, There are multiple partitions, and at least one partition is in close contact with the upper heat cut-off plate during the test.

7. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 6, characterized in that, Multiple partitions are sequentially fitted onto the tension rod from top to bottom with a certain gap between them and the tension rod. At least one partition is slidably connected to the support rod and can slide along the support rod.

8. The testing apparatus for the mechanical properties of materials under ultra-low temperature conditions according to claim 7, characterized in that, The partition consists of a first partition, a second partition, a third partition, and a fourth partition from top to bottom. The second partition is in close contact with the upper heat cut-off plate, the fourth partition is slidable along the support rod, and the second partition is connected to the tension rod via a heat transfer flexible connection.

9. The testing device for the mechanical properties of materials under ultra-low temperature conditions according to claim 1, characterized in that, The inflation device includes a pressure transmitter, a safety valve, a pressure reducing valve, an inflation pipe, an evacuation port, a helium cylinder, and a switch ball valve; the interface of the inflation pipe leading to the sample channel is located between the upper heat cutoff and the constant temperature chamber.

10. The method of using the testing device for the mechanical properties of materials under ultra-low temperature conditions according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Evacuate the inside of the low-temperature thermostat; S2: Install the sample testing mechanism and inflation device; S3: Replace the sample channel with helium. Specifically, replenish the sample channel with helium through the filling pipe. S4: Turn on the refrigeration equipment, set the control temperature, and fix the temperature of the low-temperature thermostat; S5: After the temperature of the low-temperature thermostat stabilizes, the mechanical properties can be tested by applying a load to the test piece using a tensile device.

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