Device and method for testing mechanical properties of superconducting coil structure under low temperature and variable temperature environment

Abstract

The present invention discloses a superconducting coil structure mechanical property testing device and method under low temperature and variable temperature environment, which relates to the field of stress measurement technology, and the main purpose is to improve the test accuracy and expand the measurement range of the superconducting coil structure mechanical property test. The main technical scheme of the present invention is: the test device includes: a dewar container; a temperature control component, including a refrigerator and a heater, the refrigerator includes a cold screen, a first-level cold head and a second-level cold head, the cold screen is set in the dewar container, the first-level cold head is connected to the cold screen, the second-level cold head is set in the cold screen, and the heater is set at the second-level cold head; a compression component is set in the cold screen and connected to the second-level cold head, the compression component is used to produce deformation with temperature changes to apply pressure to the superconducting coil to be tested; a detection component is set in the cold screen and is respectively connected to the compression component and the superconducting coil to be tested, and is used to detect the strain of the superconducting coil to be tested and the strain value of the compression component.

Description

Technical Field

[0001] The present invention relates to the field of stress measurement technology, and in particular to a device and method for testing the mechanical properties of a superconducting coil structure in a low-temperature variable temperature environment. Background Art

[0002] The characterization and analysis of the multi-field performance of superconducting materials and magnet structures under extremely complex operating environments is crucial for the design and preparation of superconducting magnets. Studying the electromagnetic, heat transfer and mechanical properties of superconducting magnet structures under extremely multi-fields, as well as basic mechanical problems such as the mutual coupling effect and nonlinear effect between them, is the key to ensuring the safe operation of superconducting magnet structures, and is also a hot and difficult topic in the current international superconducting technology research.

[0003] At present, a large number of laboratories at home and abroad are carrying out experimental characterization research on the equivalent parameter measurement of the mechanical properties of superconducting composite structures. Most of them are limited to room temperature or liquid nitrogen temperature. The existing equipment mostly uses liquid nitrogen or liquid helium immersion to cool the materials, which will inevitably lead to measurement errors. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a device and method for testing the mechanical properties of a superconducting coil structure in a low-temperature variable temperature environment, the main purpose of which is to improve the test accuracy of the mechanical properties test of the superconducting coil structure and expand the measurement range.

[0005] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0006] On the one hand, an embodiment of the present invention provides a superconducting coil structure mechanical property testing device in a low temperature variable temperature environment, comprising:

[0007] Dewar vessel;

[0008] A temperature control component, the temperature control component includes a refrigerator and a heater, the refrigerator includes a cold shield, a primary cold head and a secondary cold head, the cold shield is sleeved in the Dewar container, the primary cold head is connected to the cold shield, the secondary cold head is arranged in the cold shield, and the heater is arranged at the secondary cold head;

[0009] A compression assembly, the compression assembly is arranged in the cold shield and connected to the secondary cold head, the compression assembly is used to deform with temperature changes to apply pressure to the superconducting coil to be tested;

[0010] A detection component is arranged in the cold shield and is respectively connected to the compression component and the superconducting coil to be tested, and is used to detect the strain of the superconducting coil to be tested and the strain value of the compression component.

[0011] Further, the compression assembly includes a first pressure head assembly, a second pressure head assembly and a plurality of tie rods, the first pressure head assembly and the second pressure head assembly are arranged opposite to each other, and the plurality of tie rods are connected between the first pressure head assembly and the second pressure head assembly; the first pressure head assembly is connected to the secondary cold head;

[0012] The superconducting coil to be tested is placed between the first pressure head assembly and the second pressure head assembly; the pull rod is used to shorten its length as the temperature decreases, so as to drive the first pressure head assembly and the second pressure head assembly to apply pressure to the superconducting coil to be tested.

[0013] Further, the first pressing head assembly includes a first pressing head and a first supporting plate, the second pressing head assembly includes a second pressing head and a second supporting plate, the first supporting plate and the second supporting plate are arranged opposite to each other, the first supporting plate includes a first surface facing the second supporting plate, the second supporting plate includes a second surface facing the first supporting plate, the first pressing head is connected to the first surface, the second pressing head is connected to the second surface, and the first pressing head and the second pressing head are arranged opposite to each other;

[0014] The superconducting coil to be tested is placed between the first pressure head and the second pressure head;

[0015] The secondary cold head is connected to the first support plate;

[0016] A plurality of the pull rods are connected between the first support plate and the second support plate;

[0017] A first pressure detection member is provided between the first pressure head and the superconducting coil to be tested, and a second pressure detection member is provided between the second pressure head and the superconducting coil to be tested;

[0018] The first pressure head is provided with a first temperature detection member, and the second pressure head is provided with a second temperature detection member.

[0019] Furthermore, the compression assembly further comprises a heat-and-cold conductive connector, one end of which is connected to the first support plate, and the other end of which is connected to the second support plate;

[0020] The heat and cold conducting connecting piece is a flexible piece;

[0021] The heat-cold conductive connector includes a first heat-cold conductive connector and a second heat-cold conductive connector, wherein the first heat-cold conductive connector is connected to one end of the first support plate and the second support plate, and the second heat-cold conductive connector is connected to the other end of the first support plate and the second support plate.

[0022] Furthermore, the compression assembly further comprises a guide ring, one end of which is sleeved on the outside of the first pressure head, and the other end of which is sleeved on the outside of the second pressure head;

[0023] The superconducting coil to be tested is arranged inside the guide ring.

[0024] Further, the compression assembly further comprises a plurality of first locking nuts and a plurality of second locking nuts;

[0025] The first support plate is provided with a plurality of first mounting holes; the second support plate is provided with a plurality of second mounting holes, and the plurality of second mounting holes correspond one to one with the plurality of first mounting holes;

[0026] The pull rod includes a first end and a second end, the first end passes through the first mounting hole and is inserted into the corresponding second mounting hole and is threadedly connected to the first locking nut, and the second end is threadedly connected to the second locking nut.

[0027] Furthermore, the superconducting coil structure mechanical properties testing device under low temperature / temperature environment also includes:

[0028] A cooling plate, wherein the secondary cold head is connected to the first pressure head assembly through the cooling plate.

[0029] Furthermore, the cooling plate is U-shaped, and comprises a first arm and a second arm connected to each other, the outer side of the first arm is connected to the secondary cold head, and the outer side of the second arm is connected to the first pressure head assembly;

[0030] An accommodating space is arranged between the first supporting arm and the second supporting arm, and the heater is arranged in the accommodating space.

[0031] Furthermore, the detection component includes a sample strain gauge and multiple tie rod strain gauges, the multiple tie rod strain gauges are arranged on the tie rod for detecting the strain value of the tie rod, and the sample strain gauge is arranged on the superconducting coil to be tested for detecting the strain value of the superconducting coil to be tested.

[0032] Furthermore, the sample strain gauge includes a first strain gauge and a second strain gauge, the sensitive grid direction of the first strain gauge is parallel to the pressure direction, and the sensitive grid direction of the second strain gauge is perpendicular to the pressure direction.

[0033] On the other hand, an embodiment of the present invention provides a method for testing the mechanical properties of a superconducting coil structure in a low-temperature variable temperature environment, using the aforementioned device for testing the mechanical properties of a superconducting coil structure in a low-temperature variable temperature environment;

[0034] When the superconducting coil to be tested is placed in the compression assembly, controlling the refrigerator to operate;

[0035] When the temperature of the superconducting coil to be tested reaches a first preset temperature, controlling the refrigerator to stop;

[0036] controlling the operation of the heater;

[0037] In the process of increasing the temperature of the superconducting coil to be tested, obtaining a first strain value of the superconducting coil to be tested and a second strain value of the pull rod of the compression assembly at a plurality of second preset temperatures; wherein the plurality of second preset temperatures include the first preset temperature, and the difference between two adjacent second preset temperatures is the first preset value;

[0038] The elastic modulus and Poisson's ratio of the superconducting coil to be tested are determined according to the first strain value and the second strain value.

[0039] Furthermore, when the superconducting coil to be tested is placed in the compression assembly, before controlling the refrigerator to operate, the testing method further includes:

[0040] Adjusting the first locking nut and the second locking nut of the compression assembly so that the difference between the strain values ​​of the plurality of tie rod strain gauges of the detection assembly is less than or equal to a second preset value;

[0041] The sample strain gauge of the detection component and the pull rod strain gauge are cleared.

[0042] By means of the above technical solution, the present invention has at least the following beneficial effects:

[0043] In the mechanical property testing device for a superconducting coil structure under a low-temperature and variable temperature environment provided by an embodiment of the present invention, the first-level cold head of a refrigerator of a temperature control component is connected to a cold screen, the second-level cold head is connected to a compression component, and a heater is arranged at the second-level cold head. When the refrigerator is started, the first-level cold head, the cold screen and the second-level cold head can provide a low-temperature environment for the superconducting coil to be tested. When the heater is started, a variable temperature environment can be provided for the superconducting coil to be tested. Moreover, the compression component can deform with temperature changes to apply pressure to the superconducting coil to be tested. The detection component can detect the strain generated by the superconducting coil to be tested when under pressure and the strain of the compression component, thereby realizing the mechanical property testing of the superconducting coil to be tested under a low-temperature or variable temperature environment.

[0044] In the superconducting coil structure mechanical property testing device under low temperature and variable temperature environment provided by the embodiment of the present invention, a low temperature or variable temperature environment is provided for the performance test of the superconducting coil to be tested through a temperature control component, and the dependence on low temperature liquids such as liquid nitrogen or liquid helium is eliminated. The measurement data is stable and accurate, the test accuracy is improved, the measurement range is expanded, and it can also be applied to on-site tests of various working conditions; moreover, a compression component that can deform with temperature changes is used to apply pressure to the superconducting coil to be tested, rather than using a driving mechanism such as a jack to apply pressure to the superconducting coil to be tested, so that the extra heat brought by the driving mechanism when it is working to affect the test temperature of the superconducting coil to be tested is avoided, and the test accuracy is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of a superconducting coil structure mechanical performance testing device under a low temperature and variable temperature environment provided by an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of the structure of a superconducting coil to be tested provided by an embodiment of the present invention;

[0047] Figure 3 A flow chart of a method for testing the mechanical properties of a superconducting coil structure in a low-temperature variable temperature environment provided by an embodiment of the present invention.

[0048] The reference numerals are:

[0049] 1-Dewar container; 2-refrigerator; 21-cold shield; 22-first cold head; 23-second cold head; 3-compression assembly; 31-first pressure head assembly; 311-first pressure head; 312-first support plate; 32-second pressure head assembly; 321-second pressure head; 322-second support plate; 33-pull rod; 34-guide ring; 35-first locking nut; 36-second locking nut; 4-cold plate; 5-first strain gauge; 6-second strain gauge; 7-first hot and cold connector; 8-second hot and cold connector; 100-superconducting coil to be tested. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be described in more detail in conjunction with the accompanying drawings in the preferred embodiments of the present invention. In conjunction with the accompanying drawings, some implementation methods of the invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0051] like Figure 1As shown, the embodiment of the present invention provides a superconducting coil structure mechanical property testing device under low temperature variable temperature environment, including a dewar container 1; a temperature control component, including a refrigerator 2 and a heater, the refrigerator 2 includes a cold shield 21, a first-level cold head 22 and a second-level cold head 23, the cold shield 21 is sleeved in the dewar container 1, the first-level cold head 22 is connected to the cold shield 21, the second-level cold head 23 is arranged in the cold shield 21, and the heater is arranged at the second-level cold head 23; a compression component 3 is arranged in the cold shield 21 and connected to the second-level cold head 23, the compression component 3 can be deformed with temperature changes to apply pressure to the superconducting coil 100 to be tested; a detection component is arranged in the cold shield 21 and is respectively connected to the compression component 3 and the superconducting coil 100 to be tested, and is used to detect the strain of the superconducting coil 100 to be tested and the strain of the compression component 3. The superconducting coil 100 to be tested is in the shape of a cube or a cuboid.

[0052] Among them, the refrigerator 2 can be a small refrigerator, and its first-level cold head 22 is connected to the cold screen 21 to realize cooling on the cold screen 21, forming a heat shield, and providing a preliminary cold environment for the superconducting coil 100 to be tested. The second-level cold head 23 is connected to the compression assembly 3 to realize cooling for the superconducting coil 100 to be tested, thereby providing a low-temperature environment for measuring the mechanical properties of the superconducting coil 100 to be tested. The heater can be a device that can be heated, such as an electric heating plate. After the refrigerator 2 provides a low-temperature environment for the superconducting coil 100 to be tested, the refrigerator 2 is stopped and the heater is started, so that the temperature of the low-temperature environment can be increased, thereby providing a variable temperature environment for measuring the mechanical properties of the superconducting coil 100 to be tested.

[0053] In the mechanical property testing device for a superconducting coil structure under a low-temperature variable temperature environment provided by an embodiment of the present invention, the first-level cold head 22 of the refrigerator 2 of the temperature control component is connected to the cold shield 21, the second-level cold head 23 is connected to the compression component 3, and the heater is arranged at the second-level cold head 23. When the refrigerator 2 is started, the first-level cold head 22, the cold shield 21 and the second-level cold head 23 can provide a low-temperature environment for the superconducting coil 100 to be tested. When the heater is started, a variable temperature environment can be provided for the superconducting coil 100 to be tested. Moreover, the compression component 3 can be deformed with temperature changes to apply pressure to the superconducting coil 100 to be tested. The detection component can detect the strain generated by the superconducting coil 100 to be tested when under pressure and the strain of the compression component 3, thereby realizing the mechanical property test of the superconducting coil 100 to be tested under a low-temperature or variable temperature environment.

[0054] In the superconducting coil structure mechanical property testing device under low temperature and variable temperature environment provided by the embodiment of the present invention, a low temperature or variable temperature environment is provided for the performance test of the superconducting coil 100 to be tested through a temperature control component, and the dependence on low temperature liquids such as liquid nitrogen or liquid helium is eliminated. The measurement data is stable and accurate, the test accuracy is improved, the measurement range is expanded, and it can also be applied to field tests of various working conditions; moreover, a compression component 3 that can deform with temperature changes is used to apply pressure to the superconducting coil 100 to be tested, rather than using a driving mechanism such as a jack to apply pressure to the superconducting coil 100 to be tested, so that the extra heat brought by the driving mechanism when working to affect the test temperature of the superconducting coil 100 to be tested is avoided, and the test accuracy is further improved.

[0055] In some embodiments, see Figure 1 The compression assembly 3 may include a first pressing head assembly 31, a second pressing head assembly 32 and a plurality of tie rods 33. The first pressing head assembly 31 and the second pressing head assembly 32 are arranged opposite to each other, and the plurality of tie rods 33 are connected between the first pressing head assembly 31 and the second pressing head assembly 32. The first pressing head assembly 31 is connected to the secondary cold head 23. The superconducting coil 100 to be tested is placed between the first pressing head assembly 31 and the second pressing head assembly 32. The tie rods 33 are used to shorten their length as the temperature decreases, so as to drive the first pressing head assembly 31 and the second pressing head assembly 32 to apply pressure to the superconducting coil 100 to be tested.

[0056] When the refrigerator 2 is started, the temperature in the cold shield 21 gradually decreases, and the length of the pull rod 33 can be gradually shortened as the temperature decreases, thereby the distance between the first pressure head assembly 31 and the second pressure head assembly 32 gradually decreases, thereby achieving the load applied to the superconducting coil 100 to be tested. Correspondingly, when the heater is started, the temperature in the cold shield 21 gradually increases, the length of the pull rod 33 can be gradually restored, and the load assembly applied by the first pressure head assembly 31 and the second pressure head assembly 32 to the superconducting coil 100 to be tested is reduced.

[0057] It can be understood that the pull rod 33 and the superconducting coil 100 to be tested have different thermal expansion coefficients, and the thermal expansion coefficient of the pull rod 33 is larger. Moreover, the yield strength of the pull rod 33 can be greater than the yield strength of the superconducting coil 100 to be tested, so that when the temperature in the cold shield 21 decreases, the length of the pull rod 33 gradually shortens as the temperature decreases, thereby driving the first pressure head assembly 31 and the second pressure head assembly 32 to apply a load to the superconducting coil 100 to be tested. Compared with the use of a driving mechanism such as a jack to drive the first pressure head assembly 31 and the second pressure head assembly 32, which generates heat, the technical solution provided by the embodiment of the present invention does not introduce additional heat, and does not affect the test temperature of the superconducting coil 100 to be tested, thereby further improving the test accuracy.

[0058] It is understandable that the pull rod 33 can be made of any metal material with a large thermal expansion coefficient and yield strength, as long as it can be shortened at low temperatures to drive the first and second pressure head assemblies 31 and 32 to apply load to the superconducting coil 100 to be tested.

[0059] Specifically, the pull rod 33 can be made of an aluminum alloy material with known material properties. The elastic modulus of the material can be approximately regarded as a linear change with temperature. Under the temperature range of 293 K-4.3 K, the calculation formula of the elastic modulus can be expressed as:

[0060] ;

[0061] In the formula, is the elastic modulus of aluminum alloy, is the temperature, , It is a coefficient determined by the material properties. For aluminum alloy materials, the values ​​of a and b are fixed and known.

[0062] Among them, under a certain temperature condition, the mechanical performance parameters of the superconducting coil to be tested conform to the formula:

[0063] ;

[0064] ;

[0065] ;

[0066] In the formula, is the compression modulus of the superconducting coil to be tested; is the shear modulus of the superconducting coil to be tested; is the elastic modulus of the tie rod; is the strain of the tie rod; is the positive strain value of the superconducting coil to be tested; is the shear strain value of the superconducting coil to be tested, is the Poisson's ratio of the superconducting coil to be tested; r is the radius of the rod; is the length of the superconducting coil to be tested; is the width of the superconducting coil to be tested.

[0067] In some embodiments, see Figure 1The first pressing head assembly 31 may include a first pressing head 311 and a first supporting plate 312, the second pressing head assembly 32 may include a second pressing head 321 and a second supporting plate 322, the first supporting plate 312 and the second supporting plate 322 are arranged opposite to each other, the first supporting plate 312 includes a first surface facing the second supporting plate 322, the second supporting plate 322 includes a second surface facing the first supporting plate 312, the first pressing head 311 is connected to the first surface, the second pressing head 321 is connected to the second surface, and the first pressing head 311 and the second pressing head 321 are arranged opposite to each other; the superconducting coil 100 to be tested is placed between the first pressing head 311 and the second pressing head 321; the secondary cold head 23 is connected to the first supporting plate 312; and a plurality of pull rods 33 are connected between the first supporting plate 312 and the second supporting plate 322.

[0068] When the temperature in the cold shield 21 gradually decreases, the length of the pull rod 33 gradually shortens due to the temperature drop, and the first support plate 312 and the second support plate 322 gradually approach each other under the drive of the pull rod 33, thereby driving the first pressure head 311 and the second pressure head 321 to apply load to the superconducting coil 100 to be tested.

[0069] In the above embodiment, the number of the pull rods 33 can specifically be four, wherein two pull rods 33 can be connected to one end of the first support plate 312 and the second support plate 322, and the other two pull rods 33 can be connected to the other ends of the first support plate 312 and the second support plate 322; moreover, the first support plate 312 and the second support plate 322 can be arranged parallel to each other, so that when the length of the pull rods 33 is shortened due to a decrease in temperature, the first support plate 312 and the second support plate 322 can drive the first pressure head 311 and the second pressure head 321 to smoothly apply a load to the superconducting coil 100 to be tested.

[0070] In some embodiments, a first pressure detection member may be disposed between the first pressure head 311 and the superconducting coil 100 to be tested, and a second pressure detection member may be disposed between the second pressure head 321 and the superconducting coil 100 to be tested.

[0071] In the above embodiment, the first pressure detection member can be used to detect the contact state between the first pressure head 311 and the superconducting coil 100 to be tested, and the second pressure detection member can be used to detect the contact state between the second pressure head 321 and the superconducting coil 100 to be tested. If the information detected by the corresponding pressure detection member is that the corresponding pressure head is not in good contact with the superconducting coil 100 to be tested, it is necessary to adjust the connection state between the pull rod 33 and the first support plate 312 and the second support plate 322 to ensure that the superconducting coil 100 to be tested is in good contact with the first pressure head 311 and the second pressure head 321, thereby ensuring that the first pressure head 311 and the second pressure head 321 can reliably apply load to the superconducting coil 100 to be tested.

[0072] In order to ensure that the superconducting coil 100 to be tested is in good contact with the first pressure head 311 and the second pressure head 321 , both the first pressure detection member and the second pressure detection member may be pressure-sensitive paper.

[0073] In some embodiments, a first temperature detection component may be disposed on the first pressure head 311 , and a second temperature detection component may be disposed on the second pressure head 321 .

[0074] In the above embodiment, the first temperature detection member and the second temperature detection member are used to detect the temperature of the superconducting coil 100 to be tested. When the temperature values ​​detected by the first temperature detection member and the second temperature detection member are the same or close, it means that the temperature of the superconducting coil 100 to be tested has reached the temperature value. Specifically, the first temperature detection member and the second temperature detection member can both be thermometers.

[0075] In some embodiments, the compression assembly 3 may further include a heat-and-cold conductive connector, one end of which is connected to the first support plate 312 and the other end of which is connected to the second support plate 322; the heat-and-cold conductive connector may be a flexible member.

[0076] Among them, the hot and cold connecting parts can reduce the temperature difference between the first compression assembly 3 and the second compression assembly 3 as much as possible to maintain the compression assembly 3 as an isothermal body, thereby more accurately realizing the mechanical properties test of the superconducting coil 100 to be tested in a low temperature or variable temperature environment.

[0077] Further, see Figure 1 The hot and cold connecting member may include a first hot and cold connecting member 7 and a second hot and cold connecting member 8. The first hot and cold connecting member 7 is connected to one end of the first support plate 312 and the second support plate 322, and the second hot and cold connecting member 8 is connected to the other end of the first support plate 312 and the second support plate 322, so as to better maintain the compression assembly 3 as an isothermal body.

[0078] In some embodiments, see Figure 1 The compression assembly 3 may further include a guide ring 34 , one end of the guide ring 34 is sleeved on the outside of the first pressure head 311 , and the other end of the guide ring 34 is sleeved on the outside of the second pressure head 321 ; the superconducting coil 100 to be tested is arranged inside the guide ring 34 .

[0079] In the above embodiment, the guide ring 34 can ensure that the center line of the first press head 311 and the center line of the second press head 321 coincide with each other, so that when the length of the pull rod 33 is shortened as the temperature decreases, the first press head 311 and the second press head 321 can stably apply a load to the superconducting coil 100 to be tested along the direction of their center lines, thereby avoiding deviation in the load applied to the superconducting coil 100 to be tested due to the offset of the first press head 311 or the second press head 321, causing the local force on the superconducting coil 100 to be too large or too small, thereby ensuring the accuracy and reliability of the test results.

[0080] The guide ring 34 may be a cylindrical structure, and its extension direction is consistent with the extension direction of the pull rod 33. The inner walls at both ends of the guide ring 34 and the outer walls of the first and second rams 311 and 321 may be smooth surfaces. During assembly, the guide ring 34 is directly sleeved on the first and second rams 311 and 321; or, for ease of operation, internal threads are provided on the inner walls at both ends of the guide ring 34, and matching external threads are provided on the outer walls of the first and second rams 311 and 321. During assembly, the guide ring 34 is threadedly connected with the first and second rams 311 and 321. It can be understood that the first ram 311 and the first support plate 312 are split structures, and the two can be connected by fasteners such as bolts, and the second ram 321 and the second support plate 322 are split structures, and the two can be connected by fasteners such as bolts.

[0081] In some embodiments, see Figure 1 The compression assembly 3 can also include multiple first locking nuts 35 and multiple second locking nuts 36; the first support plate 312 is provided with multiple first mounting holes; the second support plate 322 is provided with multiple second mounting holes, and the multiple second mounting holes correspond one by one to the multiple first mounting holes; the pull rod 33 includes a first end and a second end, the first end passes through the first mounting hole and is inserted into the corresponding second mounting hole, and is threadedly connected to the first locking nut 35, and the second end is threadedly connected to the second locking nut 36.

[0082] Before testing, the rod 33 can be initially pre-tightened at room temperature to ensure that the first pressure head 311 and the second pressure head 321 are in good contact with the superconducting coil 100 to be tested. Specifically, the first locking nut 35 can be adjusted and tightened first, and then the second locking nut 36 can be adjusted to achieve initial pre-tightening of the rod 33.

[0083] In some embodiments, see Figure 1 The superconducting coil structure mechanical property testing device under low temperature variable temperature environment may further include a cold plate 4 , and the secondary cold head 23 is connected to the first pressure head assembly 31 through the cold plate 4 .

[0084] In the above embodiment, the cold conducting plate 4 can transfer the cold energy generated by the refrigerator 2 to the compression assembly 3 with greater efficiency, so that the temperature of the superconducting coil 100 to be tested is reduced, thereby better providing a low temperature environment for the superconducting coil 100 to be tested. The cold conducting member can be any type of component that can conduct cold energy and has a certain strength, such as a metal member.

[0085] In some embodiments, the cold conduction plate 4 is U-shaped, and the cold conduction member includes a first arm and a second arm connected to each other, the outer side surface of the first arm is connected to the secondary cold head 23, and the outer side surface of the second arm is connected to the first pressure head assembly 31, specifically connected to the first support plate 312; an accommodating space is arranged between the first arm and the second arm, and the heater is arranged in the accommodating space.

[0086] Among them, the cooling member can be a U-shaped cooling plate, the outer side of the first arm of which is connected to the secondary cold head 23, and the outer side of the second arm is connected to the first pressure head assembly 31. Such a structural arrangement, on the one hand, can make the cooling plate 4 have a certain elasticity, so that a flexible connection can be formed between the secondary cold head 23 of the refrigerator 2 and the first pressure head assembly 31, rather than a rigid connection. When the compression assembly 3 applies a load to the superconducting coil 100 to be tested, or when the device is subjected to other abnormal external forces, the cooling plate 4 can be deformed with the external force, thereby avoiding damage to the compression assembly 3 and the refrigerator 2. On the other hand, a storage space can be formed between the first arm and the second arm, and the heater can be arranged in the storage space for easy use.

[0087] Among them, the detection component can have various structural forms, as long as it can detect the strain of the superconducting coil 100 to be tested and the strain of the compression component 3. For example, the detection component can realize strain detection by means of strain gauges, fiber grating sensors, etc. When the detection component performs strain detection through strain gauges, the strain gauges can be attached to the surfaces of the superconducting coil 100 to be tested and the pull rod 33. When the superconducting coil 100 to be tested and the pull rod 33 are deformed, the resistance value of the strain gauge will change. By measuring the resistance change of the strain gauge, the strain of the superconducting coil 100 to be tested and the pull rod 33 can be obtained. When the detection component performs strain detection through fiber grating sensors, the fiber grating sensors are embedded or attached in the superconducting coil 100 to be tested and the pull rod 33. When the superconducting coil 100 to be tested and the pull rod 33 are deformed, the wavelength of the fiber grating will change. By measuring the wavelength change, the strain of the superconducting coil 100 to be tested and the pull rod 33 can be determined.

[0088] For ease of use, in some embodiments, the detection assembly may include a sample strain gauge and multiple tie rod strain gauges. The tie rod strain gauge is arranged on the tie rod 33 to detect the strain value of the tie rod 33, and the sample strain gauge is arranged on the superconducting coil to be tested to detect the strain value of the superconducting coil 100 to be tested.

[0089] Among them, the number of tie rod strain gauges on the tie rod 33 can be four, and the four tie rod strain gauges can adopt a full-bridge strain test circuit connection method. The number of sample strain gauges on the superconducting coil 100 to be tested can be two, and the two sample strain gauges can adopt a half-bridge strain measurement circuit connection method to improve the strain measurement accuracy.

[0090] In some embodiments, see Figure 2 The sample strain gauge includes a first strain gauge 5 and a second strain gauge 6. The sensitive grid direction of the first strain gauge 5 is parallel to the pressure direction, and the sensitive grid direction of the second strain gauge 6 is perpendicular to the pressure direction.

[0091] The sensitive grid direction of the first strain gauge 5 is parallel to the pressure direction, and the normal strain value of the superconducting coil 100 to be tested in the pressure direction can be measured. The sensitive grid direction of the second strain gauge 6 is perpendicular to the pressure direction, and the shear strain value of the superconducting coil 100 to be tested in the direction perpendicular to the pressure direction can be measured. Specifically, the first strain gauge 5 and the second strain gauge 6 can be attached to the same outer peripheral side of the superconducting coil 100 to be tested.

[0092] like Figure 3 As shown, an embodiment of the present invention further provides a method for testing the mechanical properties of a superconducting coil structure in a low temperature variable temperature environment, using the above-mentioned superconducting coil structure mechanical properties testing device in a low temperature variable temperature environment, and the testing method includes:

[0093] 101. When the superconducting coil to be tested is placed in the compression assembly, control the operation of the refrigerator;

[0094] It is understandable that controlling the operation of the refrigerator may specifically include: firstly evacuating the Dewar container, and then waiting for the vacuum degree inside the Dewar container to be greater than or equal to a preset value such as 10 -3 When Pa, stop vacuuming to make the refrigerator ready for start-up, and then control the refrigerator to start running.

[0095] After the refrigerator is started, it begins to cool down the superconducting coil to be tested to provide a low-temperature environment for the superconducting coil to be tested. During the cooling process, the temperature and strain value of the superconducting coil to be tested, as well as the strain value on the pull rod, are monitored in real time.

[0096] 102. When the temperature of the superconducting coil to be tested reaches a first preset temperature, control the heater to operate.

[0097] When the temperature of the superconducting coil to be tested reaches a first preset temperature, that is, when the temperature of the superconducting coil to be tested reaches a minimum temperature such as 4.2K or below, the strain value of the superconducting coil to be tested and the strain value of the pull rod can be synchronously recorded.

[0098] Then, the heater is turned on to start heating and temperature increase. Specifically, the temperature of the superconducting coil to be tested can be increased from the aforementioned lowest temperature to room temperature, so as to provide a variable temperature environment for the superconducting coil to be tested.

[0099] 103. During the temperature increase of the superconducting coil to be tested, a first strain value of the superconducting coil to be tested and a second strain value of the tension rod of the compression assembly at a plurality of second preset temperatures are obtained; wherein the plurality of second preset temperatures include a first preset temperature, and the difference between two adjacent second preset temperatures is the first preset value. It can be understood that the first strain value includes a normal strain value and a shear strain value of the superconducting coil to be tested.

[0100] That is to say, during the temperature increase of the superconducting coil to be tested, the first strain value of the superconducting coil to be tested and the second strain value of the pull rod at the corresponding temperature may be recorded at each temperature interval of the first preset value.

[0101] Among them, the multiple second preset temperatures are temperatures at each interval of the first preset value, and the multiple second preset temperatures include the first preset temperature. For example, the first preset temperature is 4.2K, and the first preset value is 10K. Then, at a temperature of 4.2K, the first strain value of the superconducting coil to be tested and the second strain value of the pull rod are recorded, at a temperature of 14.2K, the first strain value of the superconducting coil to be tested and the second strain value of the pull rod are recorded, then at a temperature of 24.2K, the first strain value of the superconducting coil to be tested and the second strain value of the pull rod are recorded, then at a temperature of 34.2K, the first strain value of the superconducting coil to be tested and the second strain value of the pull rod are recorded, and so on, so as to obtain the first strain value of the superconducting coil to be tested and the second strain value of the pull rod at each temperature.

[0102] 104. Determine the elastic modulus and Poisson's ratio of the superconducting coil to be tested according to the first strain value and the second strain value.

[0103] Data processing is performed based on the aforementioned calculation formula to calculate the elastic modulus (compression modulus and shear modulus) and Poisson's ratio of the corresponding superconducting coil sample at the same temperature.

[0104] It can be understood that multiple cooling and heating test experiments can be carried out on the same superconducting coil to be tested to examine the repeatability of the measurement data. If the repeatability is good, it means that the test data is reliable. If the repeatability is poor, the test device needs to be adjusted and the test must be repeated until the measurement data has good repeatability and the test data obtained is reliable.

[0105] Furthermore, the placement direction of the superconducting coil to be tested on the compression assembly can be changed, and the above test process can be repeated to obtain the data of the elastic modulus and Poisson's ratio of the superconducting coil to be tested in another direction as a function of temperature. Thus, the elastic modulus and Poisson's ratio of the superconducting coil in different directions at a certain temperature point in a low temperature or variable temperature environment can be finally obtained.

[0106] In an embodiment of the present invention, before step 101, the testing method may further include: adjusting the first locking nut and the second locking nut of the compression assembly so that the difference in strain values ​​of multiple tie rod strain gauges of the detection assembly is less than or equal to a second preset value; and clearing the sample strain gauge and the tie rod strain gauge of the detection assembly.

[0107] The tie rod can be initially pre-tightened at room temperature. Specifically, the first locking nut at the bottom of the tie rod can be adjusted, and then the second locking nut at the top of the tie rod can be adjusted to ensure that the strain values ​​of all tie rod strain gauges on the tie rod are close. On the premise that the strain values ​​of all tie rod strain gauges on the tie rod are close, the tie rod strain gauges on the tie rod and the sample strain gauges on the superconducting coil to be tested are cleared to ensure that the strain on the superconducting coil to be tested and the tie rod is caused by temperature changes, thereby ensuring the accuracy of the test results.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment, characterized in that: include: Dewar vessel; A temperature control component, the temperature control component includes a refrigerator and a heater, the refrigerator includes a cold shield, a primary cold head and a secondary cold head, the cold shield is sleeved in the Dewar container, the primary cold head is connected to the cold shield, the secondary cold head is arranged in the cold shield, and the heater is arranged at the secondary cold head; A compression assembly, the compression assembly is arranged in the cold shield and connected to the secondary cold head, the compression assembly is used to deform with temperature changes to apply pressure to the superconducting coil to be tested; A detection component, which is arranged in the cold shield and connected to the compression component and the superconducting coil to be tested, respectively, and is used to detect the strain of the superconducting coil to be tested and the strain value of the compression component; The compression assembly includes a first pressure head assembly, a second pressure head assembly and a plurality of tie rods, the first pressure head assembly and the second pressure head assembly are arranged opposite to each other, and the plurality of tie rods are connected between the first pressure head assembly and the second pressure head assembly; the first pressure head assembly is connected to the secondary cold head; The superconducting coil to be tested is placed between the first pressure head assembly and the second pressure head assembly; the pull rod is used to shorten its length as the temperature decreases, so as to drive the first pressure head assembly and the second pressure head assembly to apply pressure to the superconducting coil to be tested.

2. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 1, characterized in that: The first pressing head assembly includes a first pressing head and a first supporting plate, the second pressing head assembly includes a second pressing head and a second supporting plate, the first supporting plate and the second supporting plate are arranged opposite to each other, the first supporting plate includes a first surface facing the second supporting plate, the second supporting plate includes a second surface facing the first supporting plate, the first pressing head is connected to the first surface, the second pressing head is connected to the second surface, and the first pressing head and the second pressing head are arranged opposite to each other; The superconducting coil to be tested is placed between the first pressure head and the second pressure head; The secondary cold head is connected to the first support plate; A plurality of the pull rods are connected between the first support plate and the second support plate; A first pressure detection member is provided between the first pressure head and the superconducting coil to be tested, and a second pressure detection member is provided between the second pressure head and the superconducting coil to be tested; The first pressure head is provided with a first temperature detection member, and the second pressure head is provided with a second temperature detection member.

3. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 2, characterized in that: The compression assembly further comprises a heat-cooling connection piece, one end of which is connected to the first support plate, and the other end of which is connected to the second support plate; The heat and cold conducting connecting piece is a flexible piece; The heat-cold conductive connector includes a first heat-cold conductive connector and a second heat-cold conductive connector, wherein the first heat-cold conductive connector is connected to one end of the first support plate and the second support plate, and the second heat-cold conductive connector is connected to the other end of the first support plate and the second support plate.

4. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 2, characterized in that: The compression assembly further includes a guide ring, one end of which is sleeved on the outside of the first pressure head, and the other end of which is sleeved on the outside of the second pressure head; The superconducting coil to be tested is arranged inside the guide ring.

5. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 2, characterized in that: The compression assembly also includes a plurality of first locking nuts and a plurality of second locking nuts; The first support plate is provided with a plurality of first mounting holes; the second support plate is provided with a plurality of second mounting holes, and the plurality of second mounting holes correspond one to one with the plurality of first mounting holes; The pull rod includes a first end and a second end, the first end passes through the first mounting hole and is inserted into the corresponding second mounting hole and is threadedly connected to the first locking nut, and the second end is threadedly connected to the second locking nut.

6. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 1, characterized in that: Also includes: A cooling plate, wherein the secondary cold head is connected to the first pressure head assembly through the cooling plate.

7. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 6, characterized in that: The cooling plate is U-shaped, and comprises a first arm and a second arm connected to each other, the outer side of the first arm is connected to the secondary cold head, and the outer side of the second arm is connected to the first pressure head assembly; An accommodating space is arranged between the first supporting arm and the second supporting arm, and the heater is arranged in the accommodating space.

8. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 1, characterized in that: The detection component includes a sample strain gauge and a plurality of tie rod strain gauges. The plurality of tie rod strain gauges are arranged on the tie rod for detecting the strain value of the tie rod. The sample strain gauge is arranged on the superconducting coil to be tested for detecting the strain value of the superconducting coil to be tested.

9. The superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment according to claim 8, characterized in that: The sample strain gauge includes a first strain gauge and a second strain gauge. The sensitive grid direction of the first strain gauge is parallel to the pressure direction, and the sensitive grid direction of the second strain gauge is perpendicular to the pressure direction.

10. A method for testing the mechanical properties of a superconducting coil structure under a low temperature and variable temperature environment, characterized in that: Using the superconducting coil structure mechanical properties testing device under low temperature and variable temperature environment as described in any one of claims 1 to 9; When the superconducting coil to be tested is placed in the compression assembly, controlling the refrigerator to operate; When the temperature of the superconducting coil to be tested reaches a first preset temperature, controlling the heater to operate; In the process of increasing the temperature of the superconducting coil to be tested, obtaining a first strain value of the superconducting coil to be tested and a second strain value of the pull rod of the compression assembly at a plurality of second preset temperatures; wherein the plurality of second preset temperatures include the first preset temperature, and the difference between two adjacent second preset temperatures is the first preset value; The elastic modulus and Poisson's ratio of the superconducting coil to be tested are determined according to the first strain value and the second strain value.

11. The testing method according to claim 10, characterized in that: When the superconducting coil to be tested is placed in the compression assembly, before controlling the refrigerator to operate, the testing method further includes: Adjusting the first locking nut and the second locking nut of the compression assembly so that the difference between the strain values ​​of the plurality of tie rod strain gauges of the detection assembly is less than or equal to a second preset value; The sample strain gauge of the detection component and the pull rod strain gauge are cleared.

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