Variable-temperature magnetostriction measuring device capable of applying compressive pre-stress

Abstract

The invention belongs to the technical field of magnetostriction performance testing devices, and discloses a variable-temperature magnetostriction measuring device capable of applying compressive pre-stress. Comprising a magnet, a loading pressure head, a variable temperature cabin, an objective table, an air pump and a computer, the loading end of the loading pressure head is arranged in the variable-temperature cabin, and the variable-temperature cabin is arranged on the objective table; the magnet is divided into an N pole and an S pole which are respectively positioned at two ends of the whole of the loading pressure head, the variable temperature cabin and the objective table; the air pump is connected with the objective table; the computer is connected with a to-be-tested sample. According to the invention, the application of the compressive pre-stress and the temperature change are integrated in the magnetostriction measurement device, the synchronous test of the magnetostriction performance under the stress and temperature dual loading condition is realized for the first time, and the limitation of the single loading condition of the existing device is overcome. The pre-compressive stress is controlled in the mode that the air pump drives the objective table to ascend and descend, the contact pressure between a sample and the loading pressure head can be accurately adjusted, the loading process is stable and controllable, repeatability is good, and the device is suitable for magnetostrictive materials of different shapes and sizes.

Description

TECHNICAL FIELD

[0001] The present application relates to magnetostrictive performance testing device technical field, especially to a kind of variable temperature magnetostrictive measurement device of pre-stress can be applied. BACKGROUND

[0002] Magnetostrictive material is widely used in sensors, actuators and transformer devices due to its dimensional change under the action of an applied magnetic field. Existing magnetostrictive measurement devices are mainly used for measurement in a single variable environment, such as stress loading at constant temperature or temperature gradient application without external stress. In stress loading devices, the structure is generally composed of a support, a measurement coil, a laser displacement measurement module, a stress application module, etc. The support part includes a shock-absorbing base, a measurement coil for placing the sample to be tested, a rear clamping device, etc.; the stress application module includes a force application module and a force display module to apply tension or pressure to the actual working environment of the device. The temperature gradient loading type magnetostrictive measurement device usually uses ceramic heating sheets combined with a PID temperature controller for temperature control. The internal structure of the measurement coil chamber is composed of a base frame, a ceramic heating sheet base frame, a ceramic heating sheet, a temperature sensor and a measurement coil skeleton.

[0003] Existing magnetostrictive measurement devices can only perform performance testing in a single physical field (such as stress or temperature), and cannot achieve measurement under the coupling effect of temperature and stress. Stress loading devices are mainly used to simulate the tensile stress or compressive stress that the transformer core yoke is subjected to when it is fixed by clamps, bolts and other fasteners, and cannot reflect the influence of temperature gradient on magnetostrictive performance; although the temperature control device can simulate the working conditions of electrical steel in a non-uniform temperature field, it lacks stress loading means and is difficult to reproduce actual service conditions. The application scenarios of the above devices are limited, and the test results are difficult to comprehensively evaluate the performance of materials, especially rare earth super magnetostrictive materials, under the coupling effect of multiple fields. SUMMARY

[0004] The present application aims to overcome the technical defects of existing magnetostrictive measurement devices that cannot simultaneously load stress and temperature, and provides a variable temperature magnetostrictive measurement device that can apply pre-stress. This device can create a stress-temperature coupling environment for testing the performance changes of magnetostrictive materials under the action of multiple physical fields, especially suitable for comprehensive performance evaluation of rare earth super magnetostrictive materials and their devices, avoiding the problem of ignoring a variable in existing material testing.

[0005] The technical solution of the present application is as follows: a variable temperature magnetostrictive measurement device that can apply pre-stress, comprising a magnet 1, a loading ram 2, a variable temperature chamber 3, a sample stage 4, an air pump 5 and a computer 6.

[0006] The loading end of the loading indenter 2 is placed in the variable temperature chamber 3, which is placed on the loading platform 4; the magnet 1 is divided into N and S poles, which are respectively located at the two ends of the whole of the loading indenter 2, the variable temperature chamber 3 and the loading platform 4.

[0007] The air pump 5 is connected to the loading platform 4; and the computer 6 is connected to the sample 31 to be measured.

[0008] In the magnetostriction measurement aspect, a vertical and constant magnetic field is applied from bottom to top by the magnet 1, and a stress sheet is pasted on the surface of the sample to be measured; the stress sheet is connected to the computer 6 through a lead wire, and the strain of the sample to be measured under the action of the magnetic field is collected and analyzed in real time, so as to evaluate the magnetostriction performance.

[0009] In the pre-stress application aspect, the air pump 5 drives the loading platform 4 to rise, so that the sample 31 to be measured in the variable temperature chamber 3 is in contact with the loading indenter 2.

[0010] The loading indenter 2 is a solid cylinder, and the bottom surface area is larger than the contact surface with the sample to be measured.

[0011] The variable temperature chamber 3 comprises the sample 31 to be measured, an air inlet 32, a heat preservation layer 34, an S-shaped thermocouple 35, a Cr-Ni heating sheet 36 and an air outlet 39; the heat preservation layer 34 is a long rectangular open structure, and composite heat insulation material is adopted; the air inlet 32 and the air outlet 39 are respectively arranged on two opposite side walls of the heat preservation layer 34, are used for the inlet and outlet of liquid nitrogen, form a temperature-controllable flow loop, realize effective cooling, and the temperature in the cavity of the heat preservation layer 34 can be lowered to-120 DEG C at the lowest; the heating sheet is placed close to the inner wall of the heat preservation layer 34; the S-shaped thermocouple 35 is arranged on the inner side of the heating sheet 36, and is used for monitoring the temperature change in the cavity of the heat preservation layer 34 in real time.

[0012] The heating sheet 36 is a Cr-Ni alloy.

[0013] The variable temperature chamber 3 further comprises a clamping structure for fixing the sample 31 to be measured; the clamping structure comprises a bottom platform 38, a back baffle 37 and a front baffle 311; a threaded hole 33 is drilled in the center of the front baffle 311, and a hexagonal socket screw 310 is used to fix the sample 31 to be measured.

[0014] The sample 31 to be measured is a semicylindrical rare earth material.

[0015] The beneficial effects of the present application are as follows:

[0016] 1. The present application integrates the pre-stress application and the variable temperature into the magnetostriction measurement device, and for the first time realizes the synchronous test of the magnetostriction performance under the conditions of stress and temperature double loading, and overcomes the limitation of the single loading condition of the existing device.

[0017] 2. The pre-stress is controlled by driving the stage to rise with the air pump, which can accurately adjust the contact pressure between the sample and the loading indenter, and the loading process is stable, controllable and repeatable, and is suitable for magnetostrictive materials with different morphologies and sizes.

[0018] 3. The two-way temperature control system of Cr-Ni alloy heating sheet and liquid nitrogen is adopted, and the temperature control range is wide.

[0019] 4. The ventilation openings of the variable temperature chamber are symmetrically distributed, and the thermocouple is installed close to the heating sheet, so that the temperature control accuracy is high. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of a variable temperature magnetostrictive measurement device capable of applying pre-stress.

[0021] Figure 2 It is a sectional view of the variable temperature chamber.

[0022] Figure 3 It is a top view of the variable temperature chamber.

[0023] In the figure: 1-magnet; 2-loading indenter; 3-variable temperature chamber; 31-sample to be measured; 32-air inlet; 33-threaded hole; 34-thermal insulation layer; 35-S-shaped thermocouple; 36-Cr-Ni heating sheet; 37-back baffle; 38-bottom table; 39-air outlet; 310-internal hexagonal screw; 311-front baffle; 4-stage; 5-air pump; 6-computer. DETAILED DESCRIPTION

[0024] The variable temperature magnetostrictive measurement device capable of applying pre-stress of the application is shown in Figure 1 , mainly composed of a magnet 1, a loading indenter 2, a variable temperature chamber 3, a stage 4, an air pump 5 and a computer 6.

[0025] In the aspect of magnetostrictive measurement, a vertical and constant magnetic field is applied from bottom to top by the magnet 1, and a stress sheet is pasted on the surface of the sample to be measured 31, and the stress sheet is connected with the computer 6 by a lead wire, so as to collect and analyze the strain of the sample under the action of the magnetic field in real time, and evaluate the magnetostrictive performance.

[0026] In the aspect of applying pre-stress, the stage 4 is driven to rise by the air pump 5, so that the sample to be measured 31 in the variable temperature chamber 3 contacts with the loading indenter 2. The loading indenter 2 is a solid cylinder with a diameter of 2 cm and a height of 2.5 cm, and the bottom area is larger than the contact surface with the sample to be measured 31, which can ensure uniform stress transmission during loading. By adjusting the lifting amplitude of the air pump 5, pre-stress loading of different sizes can be realized.

[0027] In the aspect of variable temperature, the sectional view and top view of the internal structure of the variable temperature chamber 3 are shown in Figure 2 and Figure 3The temperature-variable chamber 3 mainly consists of an air inlet 32, an insulation layer 34, an S-type thermocouple 35, a Cr-Ni heating plate 36, and an air outlet 39. In this test case, the sample 31 to be tested is a rare earth material semi-cylinder with a diameter of 0.6 cm and a height of 1.2 cm. The insulation layer 34 is 10×10×3.8 cm in size. 3 The rectangular opening structure uses composite insulation materials to ensure stable temperature within the chamber during measurement. An air inlet 32 ​​and an air outlet 39, each with a diameter of 1 cm, are machined into the left and right walls of the insulation layer 34 for the introduction and discharge of liquid nitrogen, forming a temperature-controllable flow circuit for effective cooling, allowing the temperature within the chamber to drop to as low as -120°C. The heating plate 36 is made of a Cr-Ni alloy with a diameter of 5 cm and a height of 2.5 cm and is placed close to the inner wall of the insulation layer. This heater has excellent thermal stability and can provide a high-temperature environment of up to 300°C. An S-type thermocouple 35 is located inside the heating plate 36 to monitor temperature changes within the chamber in real time. Based on temperature feedback information, the heating and cooling rates can be precisely controlled, thereby improving the accuracy of the test results. In addition, a clamping structure for securing the sample is provided within the variable temperature chamber. This clamping structure primarily consists of a base 38, a rear baffle 37, and a front baffle 311. A threaded hole 33 with a diameter of 3 mm is drilled in the center of the front baffle 311, which is used to fix the sample to be tested with the hexagon socket screw 310.

[0028] The temperature-dependent magnetostrictive measurement device designed in this paper, capable of applying prestress, significantly enhances the ability to test magnetostrictive materials under complex loading conditions. It is particularly suitable for multi-field coupling experiments requiring simultaneous stress and temperature loading. Compared to existing magnetostrictive testing systems that can only adjust either the magnetic field or the temperature independently, this device achieves efficient switching and stable loading through an integrated structure, effectively improving the reliability of measurement data.

[0029] In terms of temperature control precision, the accompanying thermocouples provide real-time monitoring, and the Cr-Ni heating plate achieves a heating rate of up to 10°C / min, with temperature fluctuations controlled within ±0.5°C. After liquid nitrogen cooling, the lowest temperature measured can reach -120°C, covering the main operating temperature range of rare earth magnetostrictive materials in practical applications. In terms of stress loading, continuous loading within the range of 0 to 20 MPa can be achieved by regulating the air pump's lift and fall, with a loading error of less than 1%, effectively simulating actual prestressed working conditions.

[0030] In experimental verification, this device tested the magnetostrictive properties of a TbDyFe rare-earth magnetostrictive alloy under different temperatures and prestress conditions. This has important application value in revealing the synergistic mechanism of rare-earth giant magnetostrictive materials under the influence of magnetic field, temperature, and stress. Furthermore, the present invention offers advantages such as easy installation and disassembly, simple operation, low user barriers, and minimal human error.

Claims

1. A temperature-varying magnetostriction measuring device capable of applying prestress, characterized in that: The variable temperature magnetostriction measuring device capable of applying prestress comprises a magnet (1), a loading pressure head (2), a variable temperature chamber (3), a loading platform (4), an air pump (5) and a computer (6); The loading end of the loading head (2) is placed in the temperature-changing chamber (3), and the temperature-changing chamber (3) is placed on the loading platform (4); the magnet (1) is divided into an N pole and an S pole, which are respectively located at the two ends of the loading head (2), the temperature-changing chamber (3), and the loading platform (4); The air pump (5) is connected to the stage (4); and the computer (6) is connected to the sample to be tested (31).

2. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 1, characterized in that: In terms of magnetostriction measurement, a vertically constant magnetic field is applied from bottom to top by a magnet (1), and a stress plate is attached to the surface of the sample to be tested. The stress plate is connected to a computer (6) via a lead to collect and analyze the strain of the sample to be tested under the action of the magnetic field in real time to evaluate its magnetostrictive performance.

3. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 1, characterized in that: In applying pre-stress, the air pump (5) drives the stage (4) to rise, so that the sample to be tested (31) in the temperature-changing chamber (3) contacts the loading pressure head (2).

4. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 3, characterized in that: The loading pressure head (2) is a solid cylinder, and the bottom surface area thereof is larger than the contact surface with the sample to be tested.

5. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 1, characterized in that: The temperature-variable chamber (3) comprises a sample to be tested (31), an air inlet (32), a thermal insulation layer (34), an S-type thermocouple (35), a Cr-Ni heating plate (36) and an air outlet (39); the thermal insulation layer (34) is a rectangular open structure and adopts a composite thermal insulation material; an air inlet (32) and an air outlet (39) are respectively provided on two opposite side walls of the thermal insulation layer (34) for the introduction and discharge of liquid nitrogen, forming a temperature-controllable flow circuit to achieve effective cooling; the temperature inside the cavity of the thermal insulation layer (34) can be reduced to -120°C at the lowest; the heating plate is placed close to the inner wall of the thermal insulation layer (34); the S-type thermocouple (35) is arranged on the inner side of the heating plate (36) for real-time monitoring of the temperature change inside the cavity of the thermal insulation layer (34).

6. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 5, characterized in that: The heating plate (36) is made of Cr-Ni alloy.

7. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 5, characterized in that: The temperature-changing chamber (3) is further provided with a clamping structure for fixing the sample to be tested (31); the clamping structure comprises a base (38), a rear baffle (37) and a front baffle (311); a threaded hole (33) is drilled in the center of the front baffle (311), and the sample to be tested (31) is fixed in cooperation with a hexagon socket screw (310).

8. The temperature-varying magnetostriction measuring device capable of applying prestress according to claim 1, characterized in that: The sample (31) to be tested is a semi-cylindrical rare earth material.

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