Solid propellant resistivity testing device and testing method based on force and heat coupling loading

Abstract

The invention relates to a mechanical and thermal coupling loading solid propellant resistivity testing device and testing method, belongs to the technical field of resistivity testing, and solves the problem that the resistivity of a solid propellant cannot be accurately measured under the action of mechanical and thermal coupling in the prior art. The testing device comprises a vacuum chamber, a microscopic imaging assembly, a probe seat, a force and heat coupling loading device and an electric control three-dimensional displacement platform, the force and heat coupling loading device comprises a mechanical loading assembly and a temperature loading unit, and a closed thermal medium circulation loop formed by the temperature loading unit and a corrugated pipe is used for carrying out temperature loading on a dumbbell-shaped sample. The mechanical loading assembly is used for stretching the dumbbell-shaped sample, the probe seat is connected with a probe measuring point in the dumbbell-shaped sample through the probe extension copper wire, then the probe seat applies electrical excitation to the dumbbell-shaped sample, and finally test data for calculating the resistivity of the solid propellant is obtained through measurement. The influence trend of the temperature and deformation coupling effect on the resistivity of the solid propellant can be accurately tested, and the repeatability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of resistivity testing, and particularly to a resistivity testing device and method for solid propellant under coupled force and heat loading. Background Art

[0002] The development of electro-controlled solid propellant has broken through the technical bottlenecks of traditional solid propellants in aspects such as repeatable ignition and adjustable thrust. By applying the required voltage to the electro-controlled solid propellant through electrodes, the propellant can be ignited and continuously burned without an ignition charge. When the voltage applied to the propellant is removed, the propellant goes out, and when the voltage is reapplied, the propellant can burn again. Additionally, by changing the magnitude of the applied voltage, the burning rate of the propellant can be controlled, thereby achieving the adjustment of thrust.

[0003] Solid propellant is a particle-reinforced energetic composite material composed of a polymer matrix and filler particles. The solid rocket motor is subjected to various different forms of loads during its entire life cycle from production, transportation, handling, storage to final launch. When stored vertically for a long time, it is subjected to tensile / compressive stress, which is prone to irreversible deformation damage, resulting in internal damage such as holes and cracks in the propellant, affecting the overall resistivity of the solid propellant; during long-distance transportation across temperature zones, affected by the temperature span, the solid propellant undergoes complex pyrolysis behavior and pyrolysis products, which also cause changes in the resistivity of the propellant. The resistivity changes caused by temperature and deformation seriously affect the ignition reliability and combustion performance of solid motors. Currently, in the existing technology, the research on solid propellants is limited to the testing of resistivity (see "H. Hu, Y. Ding, Study on combustion characteristics of ammonium perchlorate-enhanced hydroxylamine nitrate-based electronically controlled solid propellant, Chemical Engineering Journal, 500 (2024) 157366") or the study of the conductivity characteristics of solid propellants at different temperatures without applying mechanical loads (see "Bao Lirong et al. Thermal decomposition and conductivity characteristics of HAN-based electronically controlled solid propellant [J]. Energetic Materials, 2019, Vol. 27, No. 9, 743-748"). There is still a lack of a testing device that can simultaneously apply temperature loads and mechanical loads to solid propellants and obtain the resistivity of solid propellants. Therefore, it is of great significance to develop a resistivity testing device for solid propellants under coupled force and heat loading. Summary of the Invention

[0004] The object of the present invention is to provide a resistivity testing device and method for solid propellants under coupled force and heat loading, so as to solve the problem that the traditional technology cannot accurately measure the resistivity of solid propellants under the action of coupled force and heat. The testing device and method of the present invention use a closed thermal medium circulation loop in a vacuum chamber composed of a temperature loading unit and a bellows to perform temperature loading on a dumbbell-shaped specimen, use a mechanical loading component to stretch the dumbbell-shaped specimen, connect the probe seat and the probe measuring point inside the dumbbell-shaped specimen through a probe extension copper wire, and then apply an electrical excitation to the dumbbell-shaped specimen by the probe seat and measure to obtain the test data for calculating the resistivity of the solid propellant, which can accurately test the influence trend of the coupling effect of temperature and deformation amount on the resistivity of the solid propellant, and provide an important technical means for exploring the ignition reliability and combustion regulation performance of the solid propellant under the action of temperature and deformation.

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

[0006] A resistivity testing device for solid propellants under coupled force and heat loading, comprising:

[0007] A vacuum chamber, which is in a vacuum environment inside during resistivity testing;

[0008] A microscopic imaging assembly installed on the vacuum chamber, which is used to collect the surface morphology images of a dumbbell-shaped specimen prepared from a solid propellant. Probe measuring points are respectively embedded inside the two ends of the gauge section of the dumbbell-shaped specimen. Each probe measuring point is electrically connected to one end of a corresponding probe extension copper wire. The other end of each probe extension copper wire extends out of the surface of the dumbbell-shaped specimen and is exposed, and the probe extension copper wire bends along with the stretching of the dumbbell-shaped specimen;

[0009] A pair of probe seats installed on the vacuum chamber through probe flanges, which are used to apply an electrical excitation to the dumbbell-shaped specimen and measure to obtain the test data for calculating the resistivity of the solid propellant. The two ends of the pair of probe seats located inside the vacuum chamber are respectively electrically connected to the exposed ends of the corresponding probe extension copper wires;

[0010] A coupled force and heat loading device arranged in the vacuum chamber and used to install the dumbbell-shaped specimen, which is used to simultaneously apply mechanical load and temperature load to the dumbbell-shaped specimen;

[0011] An electronically controlled three-dimensional displacement platform used to carry the coupled force and heat loading device and fixed to the chamber wall of the vacuum chamber, which is used to adjust the relative position between the dumbbell-shaped specimen installed on the coupled force and heat loading device and the microscopic imaging assembly.

[0012] Correspondingly, the present invention also provides a resistivity testing method for solid propellants under coupled force and heat loading, comprising the following steps:

[0013] S1: Prepare the dumbbell-shaped specimen and clean the probe extension copper wire.

[0014] S2: Install the dumbbell-shaped specimen in the fixture, connect the probe extension copper wire to the probe base, and evacuate the vacuum chamber to a preset vacuum degree.

[0015] S3: Adjust the electronically controlled three-dimensional displacement platform to align the high-speed camera in the microscopic imaging component with the gauge section of the dumbbell-shaped specimen.

[0016] S4: Start the temperature loading unit, adjust the temperature of the heat medium in the heat medium heat exchange plate to make the temperature of the dumbbell-shaped specimen reach the target temperature and keep it warm for a preset duration.

[0017] S5: Control the driving motor to rotate to make the fixture uniformly stretch the dumbbell-shaped specimen to the target length, and synchronously collect the surface topography images of the upper surface of the dumbbell-shaped specimen during the stretching process by using the high-speed camera.

[0018] S6: Measure the voltage value and current value corresponding to the gauge section of the dumbbell-shaped specimen through the probe base, and calculate the resistivity of the solid propellant according to the measured voltage value, current value and the size parameters of the gauge section of the dumbbell-shaped specimen.

[0019] The beneficial effects of the present invention are as follows: Through the resistivity test device for solid propellants with force-thermal coupling loading of the present invention, the change trend of the resistivity of solid propellants under the coupling action of different temperature loads and different strain rates can be obtained. In the mechanical loading component, the probe measuring points embedded inside the dumbbell-shaped specimen move along with the elongation of the specimen and are always located at the end of the gauge section of the specimen, ensuring the accuracy of resistivity measurement. Both the temperature loading unit and the fixture are driven by the loading crossbeam to move linearly, which can keep the dumbbell-shaped specimen under stable temperature loading during tensile loading and further ensure the accuracy of resistivity measurement. The temperature loading unit uses a heat-conducting copper bar to connect the sliding heat-conducting block and the fixture, which can effectively avoid the deviation of mechanical load measurement caused by rigid connection while ensuring stable heat conduction, thus ensuring the accuracy of mechanical loading. The present invention comprehensively considers the influence of temperature stability, change of specimen resistivity test interval and accuracy of mechanical load measurement on the accuracy of resistivity measurement during tensile loading, making the test data more accurate and highly repeatable. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0021] Figure 1 Schematic diagram of the overall structure of the resistivity test device for solid propellant with force-thermal coupling loading according to the embodiment of the present invention;

[0022] Figure 2 Schematic diagram of the structure of the force-thermal coupling loading device;

[0023] Figure 3 Schematic diagram of the enlarged cross-sectional structure of the temperature loading unit;

[0024] Figure 4 Schematic diagram of the structure of the dumbbell-shaped specimen.

[0025] Explanation of reference numerals: 1. Vacuum chamber; 101. Chamber wall; 102. Camera imaging flange; 103. Probe flange; 104. Heat conduction channel flange; 105. Bellows;

[0026] 2. Microscopic imaging assembly; 201. High-speed camera; 202. Imaging transparent window; 203. Focus adjustment bracket;

[0027] 3. Probe base;

[0028] 4. Force-thermal coupling loading device;

[0029] 40. Mechanical loading assembly; 401. Lead screw; 402. Loading cross beam; 403. Clamp; 404. Installation base;

[0030] 41. Temperature loading unit; 410. Heat exchange plate bracket; 411. Heat medium heat exchange plate; 412. Sliding heat conduction seat; 413. Sliding heat conduction seat bracket; 414. Sliding heat conduction seat traction bracket; 415. Compression screw; 416. Rolling bearing; 417. Sliding heat conduction block; 418. Heat conduction copper bar; 419. Specimen heat conduction plate;

[0031] 5. Solid propellant test assembly; 501. Dumbbell-shaped specimen; 502. Probe extension copper wire; 503. Probe measurement point;

[0032] 6. Electrically controlled three-dimensional displacement platform; 601. X-direction displacement platform; 602. Y-direction displacement platform; 603. Z-direction displacement platform;

[0033] 7. Protection housing. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] See Figures 1 to 4 , this embodiment provides a resistivity testing device for solid propellant under force-thermal coupling loading. The testing device mainly includes a vacuum chamber 1, a microscopic imaging component 2, a pair of probe seats 3, a force-thermal coupling loading device 4 installed with a solid propellant testing component 5, and an electronically controlled three-dimensional displacement platform 6. The solid propellant testing component 5 includes a dumbbell-shaped specimen 501 made of solid propellant, and also includes a probe extension copper wire 502 and a probe measurement point 503. Probe measurement points 503 are respectively embedded inside the two ends of the gauge section of the dumbbell-shaped specimen 501. Each probe measurement point 503 is conductively connected to one end of the corresponding probe extension copper wire 502. The other end of each probe extension copper wire 502 extends out of the surface of the dumbbell-shaped specimen 501 and is exposed for connection to the probe seat 3. And the probe extension copper wire 502 is a flexible wire, which will bend with the stretching of the dumbbell-shaped specimen 501 to avoid introducing additional stress and ensure the accuracy of resistivity testing. The specimen in this embodiment is designed in a dumbbell shape, which is convenient for clamping the specimen and enables the specimen ends to have a larger contact area, thereby ensuring a more reliable clamping effect of the specimen. It should be noted, however, that the dumbbell-shaped specimen 501 in this embodiment can also be implemented in other common shapes, such as a long strip shape, etc., which all fall within the protection scope of the present invention.

[0036] The vacuum chamber 1 is a sealable cavity that can be evacuated. The inside of the vacuum chamber 1 is in a vacuum environment during resistivity testing. A variety of flange interfaces are opened on the cavity wall 101 of the vacuum chamber 1. The variety of flange interfaces include a camera imaging flange 102, a probe flange 103, and a heat conduction channel flange 104. The camera imaging flange 102 is arranged on the cavity wall 101 opposite to the dumbbell-shaped specimen 501 installed on the mechanical loading component 40. A probe seat 3 is installed on each of the two probe flanges 103. The heat conduction channel flange 104 is connected to the temperature loading unit 41 through a corrugated pipe 105. The heat conduction channel flange 104, the corrugated pipe 105, and the heat medium heat exchange plate 411 form a closed flow path.

[0037] The microscopic imaging assembly 2 is installed on the vacuum chamber 1 and is used to collect surface topography images of the dumbbell-shaped specimen 501. Further, the microscopic imaging assembly 2 includes a high-speed camera 201, an imaging transparent window 202, and a distance adjustment bracket 203. Among them, the imaging transparent window 202 is fixedly installed on the camera imaging flange 102, and the high-speed camera 201 is connected to the chamber wall 101 of the vacuum chamber 1 through the distance adjustment bracket 203. The high-speed camera 201 observes and collects surface topography images of the dumbbell-shaped specimen 501 through the imaging transparent window 202, and transmits the collected surface topography images to subsequent image processing devices for image processing and analysis by the image processing devices.

[0038] After the probe holder 3 is installed on the probe flange 103, one end of the probe holder 3 located inside the vacuum chamber 1 is electrically connected to one end of the corresponding probe extension copper wire 502 exposed outside the dumbbell-shaped specimen 501. The two probe holders 3 are respectively electrically connected to the corresponding probe extension copper wires 502, thereby forming an electric current loop among the probe holder 3, the probe extension copper wire 502, and the dumbbell-shaped specimen 501. Under the action of an externally connected voltage source, the two probe holders 3 apply an electrical excitation to the dumbbell-shaped specimen 501, and at the same time, test data for calculating the resistivity of the solid propellant is obtained by measuring through the probe holder 3. The test data includes voltage values and current values. Furthermore, based on the test data and the dimensional parameters of the gauge section of the dumbbell-shaped specimen 501, the resistivity of the solid propellant can be calculated. , and the specific calculation formula is as follows:

[0039] (1)

[0040] Among them, is the current voltage value applied at both ends of the gauge section, is the current current value, is the current cross-sectional area of the gauge section, is the current length of the gauge section.

[0041] The force-thermal coupling loading device 4 is connected to the chamber wall 101 of the vacuum chamber 1 through the electric control three-dimensional displacement platform 6, that is, the bottom of the electric control three-dimensional displacement platform 6 is fixed to the chamber wall 101 of the vacuum chamber 1, and the top of the electric control three-dimensional displacement platform 6 carries and fixes the force-thermal coupling loading device 4. The electric control three-dimensional displacement platform 6 is mainly used to adjust the relative position between the dumbbell-shaped specimen 501 installed on the force-thermal coupling loading device 4 and the microscopic imaging assembly 2, so that the high-speed camera 201 can observe and collect high-quality surface topography images of the dumbbell-shaped specimen 501.

[0042] Furthermore, the electronically controlled three-dimensional displacement platform 6 includes an X-direction displacement platform 601, a Y-direction displacement platform 602, and a Z-direction displacement platform 603. The X-direction displacement platform 601 is used to adjust the lateral position of the dumbbell-shaped specimen 501 relative to the high-speed camera 201. The Y-direction displacement platform 602 is used to adjust the longitudinal position of the dumbbell-shaped specimen 501 relative to the high-speed camera 201. The Z-direction displacement platform 603 is used to adjust the vertical position of the dumbbell-shaped specimen 501 relative to the high-speed camera 201. Therefore, moving the X-direction displacement platform 601 and the Y-direction displacement platform 602 can adjust the imaging area of the high-speed camera 201 relative to the dumbbell-shaped specimen 501, and moving the Z-direction displacement platform 603 can adjust the imaging distance of the high-speed camera 201.

[0043] The force-thermal coupling loading device 4 is arranged inside the vacuum chamber 1, and the dumbbell-shaped specimen 501 is installed on the force-thermal coupling loading device 4 for synchronously applying mechanical load and temperature load to the dumbbell-shaped specimen 501. Specifically, the force-thermal coupling loading device 4 includes a mechanical loading assembly 40 for stretching the dumbbell-shaped specimen 501 and a temperature loading unit 41 for adjusting the temperature of the dumbbell-shaped specimen 501. The mechanical loading assembly 40 includes a sliding guide rail, a driving motor, a lead screw 401, a pair of loading crossbeams 402, a fixture 403, and a mounting base 404. Among them, the lead screw 401 is installed in parallel on the mounting base 404. One end of the lead screw 401 is fixedly connected to the output shaft of the driving motor, and the other end is rotatably connected to a fixed plate on the mounting base 404. The driving motor drives the lead screw 401 to rotate. The sliding guide rail is parallel to the lead screw 401 and is fixed on the mounting base 404. The bottom of each loading crossbeam 402 is fixedly connected to a corresponding slider on the sliding guide rail. The loading crossbeam 402 can slide along the sliding guide rail. At the same time, one end of each loading crossbeam 402 is sleeved on the lead screw 401 and is in threaded cooperation with the lead screw 401. The driving motor drives the lead screw 401 to rotate, thereby driving the loading crossbeam 402 to move along the axis direction of the lead screw 401. The other ends of the two loading crossbeams 402 are fixed with the fixture 403, and the dumbbell-shaped specimen 501 is installed in the fixture 403. The temperature loading unit 41 is connected to the side wall of the loading crossbeam 402 through a sliding heat conduction seat traction bracket 414. Therefore, the loading crossbeam 402 can drag some components in the fixture 403 and the temperature loading unit 41 to move synchronously and linearly at a constant speed.

[0044] The temperature loading unit 41 specifically includes a heat exchange plate support 410, a heat medium heat exchange plate 411, a sliding heat conduction seat 412, a sliding heat conduction seat support 413, a sliding heat conduction seat traction support 414, a compression screw 415, a rolling bearing 416, a sliding heat conduction block 417, a heat conduction copper bar 418, and a specimen heat conduction plate 419. The specimen heat conduction plate 419 is located on the fixture 403, and the specimen heat conduction plate 419 contacts the lower surface of the dumbbell-shaped specimen 501, and is used to conduct heat for the dumbbell-shaped specimen 501. The heat exchange plate support 410 is arranged between the heat medium heat exchange plate 411 and the mounting base 404, and is used to support and fix the heat medium heat exchange plate 411. The two ends of the heat medium heat exchange plate 411 contact the two ends of the heat exchange plate support 410 and are fixedly connected through screws and their mounting holes. The heat exchange plate support 410 also plays the role of support and heat insulation, avoiding the direct transfer of the heat of the heat medium heat exchange plate 411 to other components. The inner surfaces of the two sliding heat conduction blocks 417 are respectively closely attached to the inner sides of the heat medium heat exchange plate 411. The two sliding heat conduction seats 412 are respectively fixedly connected to the corresponding sliding heat conduction blocks 417 through the sliding heat conduction seat supports 413. And the compression screw 415 is installed on the sliding heat conduction seat 412 through threads. Inside each sliding heat conduction seat 412, through the pressing action of the compression screw 415 on the rolling bearing 416, the rolling bearing 416 contacts the outer side surface of the heat medium heat exchange plate 411, ensuring that the sliding heat conduction block 417 and the sliding heat conduction seat 412 can slide on the two side surfaces of the heat medium heat exchange plate 411. Further, in this embodiment, the number of rolling bearings 416 can be set to one, or can be set to two or more. For example, two juxtaposed rolling bearings 416 are provided inside each sliding heat conduction seat 412. The inner rings of the two rolling bearings 416 are fixedly connected through a connecting rod. One end of the compression screw 415 located inside the sliding heat conduction seat 412 is threadedly connected to the connecting rod, thereby fixedly connecting the connecting rod to the side wall of the sliding heat conduction seat 412. By rotating the compression screw 415, the magnitude of the acting force between the rolling bearing 416 and the outer side surface of the heat medium heat exchange plate 411 can be adjusted.

[0045] Both ends of each heat conduction copper bar 418 are respectively closely attached to the outer surface of the corresponding sliding heat conduction block 417 and the lower surface of the specimen heat conduction plate 419, and the close attachment is achieved in a plane contact manner to improve the heat conduction efficiency. Each sliding heat conduction seat support 413 is fixedly connected to the corresponding side of the loading cross beam 402 through the sliding heat conduction seat traction support 414, so that the sliding heat conduction seat 412, the sliding heat conduction seat support 413, the sliding heat conduction block 417, the heat conduction copper bar 418, and the specimen heat conduction plate 419 can move synchronously with the loading cross beam 402.

[0046] The interior of the heat medium heat exchange plate 411 is provided with a heat medium channel. The end of the heat medium heat exchange plate 411 is welded with a bent copper tube, such as Figure 2As shown, the flow channel of the copper tube is communicated with the heat medium channel inside the heat medium heat exchange plate 411. The corrugated pipe 105 is communicated with the heat medium channel inside the heat medium heat exchange plate 411 through the copper tube to form a closed heat medium circulation loop. The corrugated pipe 105 is communicated with an external heat source through the heat conduction channel flange 104 on the cavity wall 101. The heat medium and temperature adjustment required are provided by the heat source. The heat source can be realized by a high and low temperature integrated machine, which heats the silicone oil inside by a heating rod or compresses the liquid by a compressor to heat or refrigerate it. The liquid after heating or refrigeration flows into the heat medium heat exchange plate 411 through the corrugated pipe 105 as the heat medium. The heat of the heat medium is finally conducted to the dumbbell-shaped specimen 501 through the corrugated pipe 105, the heat medium heat exchange plate 411, the sliding heat conduction block 417, the heat conduction copper row 418 and the specimen heat conduction plate 419 in sequence. Further, the shape of the heat medium channel can adopt a meandering channel, including but not limited to an S-shaped or U-shaped channel, etc. The number of channels can also be multiple. When the heat medium channel is a U-shaped channel, one end of the U-shaped channel is communicated with the heat medium input corrugated pipe, and the other end is communicated with the heat medium output corrugated pipe. Both the heat medium input corrugated pipe and the heat medium output corrugated pipe are communicated with the heat source through the heat conduction channel flange 104. The U-shaped heat medium channel can extend the flow path of the heat medium in the heat medium heat exchange plate 411, which is beneficial to improving the heat exchange efficiency.

[0047] Further, the force and heat coupling loading device 4 further includes a protective housing 7. The protective housing 7 is arranged on the side of the force and heat coupling loading device 4 close to the lead screw 401, which is used to partially cover the mechanical loading component 40. While avoiding damage to components during handling, it also has functions such as dust prevention and aesthetics.

[0048] The working process of the test device in this embodiment is as follows: First, the imaging area of the high-speed camera 201 relative to the dumbbell-shaped specimen 501 is adjusted by the electric control three-dimensional displacement platform 6, so that the high-speed camera 201 can clearly observe the gauge section of the dumbbell-shaped specimen 501. The temperature loading unit 41 conducts heat to the dumbbell-shaped specimen 501 installed in the fixture 403, and then the mechanical loading component 40 stretches the dumbbell-shaped specimen 501. At the same time, an electrical excitation is applied by the probe holder 3 and resistivity test data is measured and obtained.

[0049] The resistivity testing device for solid propellants with coupled force and heat loading proposed in this embodiment integrates a vacuum chamber, a microscopic imaging component, a coupled force and heat loading device, and an electronically controlled three-dimensional displacement platform, realizing the synchronous and accurate loading of temperature and mechanical loads on solid propellants under simulated real working conditions. By using embedded probe measurement points and probe extension copper wires to collect electrical signals in real time, it solves the problem in traditional technologies of being unable to accurately measure the resistivity of solid propellants under the action of coupled force and heat. At the same time, through the use of a surface contact design of a heat-conducting copper busbar and a cooperative structure of a sliding heat-conducting block and a rolling bearing, it ensures the synchronous improvement of heat conduction efficiency and mechanical loading stability in a high-temperature and high-pressure environment. With the vacuum environment isolating external interference, it significantly improves the accuracy and repeatability of resistivity test data, providing key technical support for the optimization of ignition reliability and precise thrust regulation of solid propellants.

[0050] In another embodiment, the present invention provides a method for testing the resistivity of solid propellants with coupled force and heat loading by applying the testing device described in the foregoing embodiment. The method includes the following steps:

[0051] S1: Use a specimen cutter to cut a solid propellant blank to obtain a dumbbell-shaped specimen 501, and clean the probe extension copper wire 502 to remove the solid propellant waste adhered to the probe extension copper wire 502.

[0052] S2: Install the dumbbell-shaped specimen 501 in the fixture 403, then connect the probe extension copper wire 502 to the probe base 3, close the vacuum chamber 1 and evacuate the air inside it to make the vacuum degree of the vacuum chamber 1 reach a preset vacuum degree, for example, make the vacuum degree reach 0.5 Pa.

[0053] S3: Adjust the electronically controlled three-dimensional displacement platform 6 to align the high-speed camera 201 in the microscopic imaging component 2 with the gauge section of the dumbbell-shaped specimen 501. For example, first adjust the Z-direction displacement platform 603 so that the high-speed camera 201 can clearly observe the upper surface of the dumbbell-shaped specimen 501, and then adjust the X-direction displacement platform 601 and the Y-direction displacement platform 602 respectively so that the high-speed camera 201 can observe the gauge section of the upper surface of the dumbbell-shaped specimen 501.

[0054] S4: Start the temperature loading unit 41, adjust the temperature of the heat medium in the heat medium heat exchange plate 411 to make the temperature of the dumbbell-shaped specimen 501 reach the target temperature, and keep it warm for a preset duration, for example, keep it warm for 30 min.

[0055] S5: Control the rotation of the driving motor, thereby controlling the movement of the mechanical loading component 40, so that the fixture 403 uniformly stretches the dumbbell-shaped specimen 501 to the target length, and use the high-speed camera 201 to synchronously collect the morphological images of the gauge section of the dumbbell-shaped specimen 501 during the stretching process.

[0056] S6: Measure the corresponding voltage value and current value of the gauge section of the dumbbell-shaped specimen 501 through the probe holder 3, and then calculate the resistivity of the solid propellant according to the measured voltage value, current value and the dimensional parameters of the gauge section of the dumbbell-shaped specimen 501. The calculation formula for the resistivity of the solid propellant can refer to the previous formula (1) and will not be elaborated here.

[0057] The resistivity test method of the solid propellant under force-thermal coupling loading proposed in this embodiment realizes the accurate measurement of the resistivity change of the solid propellant under the action of force-thermal coupling through steps such as specimen pretreatment, vacuum pumping treatment, specimen morphology monitoring, temperature loading, synchronous control of mechanical deformation and real-time electrical parameter acquisition, breaking through the limitations of traditional single-factor tests, and providing key technical support for the ignition reliability optimization and thrust precise regulation of the solid propellant.

[0058] In the present invention, specific embodiments are used to elaborate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation on the protection scope of the present invention.

Claims

1. A resistivity testing device for solid propellants under thermo-mechanical coupling loading, characterized in that Comprising: A vacuum chamber (1) which has a vacuum environment inside during resistivity testing; A microscopic imaging assembly (2) installed on the vacuum chamber (1) for collecting surface topography images of a dumbbell-shaped specimen (501) prepared from solid propellant. Probe measuring points (503) are respectively embedded inside the two ends of the gauge section of the dumbbell-shaped specimen (501). One end of each probe measuring point (503) is electrically connected to one end of a corresponding probe extension copper wire (502). The other end of each probe extension copper wire (502) extends out of the surface of the dumbbell-shaped specimen (501) and is exposed, and the probe extension copper wire (502) bends as the dumbbell-shaped specimen (501) is stretched; A pair of probe seats (3) installed on the vacuum chamber (1) through probe flanges (103) for applying an electrical excitation to the dumbbell-shaped specimen (501) and measuring test data for calculating the resistivity of solid propellant. One end of the two probe seats (3) located inside the vacuum chamber (1) is respectively electrically connected to the exposed end of the corresponding probe extension copper wire (502); A force-thermal coupling loading device (4) arranged inside the vacuum chamber (1) and for installing the dumbbell-shaped specimen (501), for synchronously applying a mechanical load and a temperature load to the dumbbell-shaped specimen (501); An electronically controlled three-dimensional displacement platform (6) for carrying the force-thermal coupling loading device (4) and fixed to the chamber wall (101) of the vacuum chamber (1), for adjusting the relative position between the dumbbell-shaped specimen (501) installed on the force-thermal coupling loading device (4) and the microscopic imaging assembly (2).

2. The resistivity testing device for solid propellant under coupled mechanical and thermal loading according to claim 1, wherein The force-thermal coupling loading device (4) includes a mechanical loading assembly (40) for stretching the dumbbell-shaped specimen (501) and a temperature loading unit (41) for adjusting the temperature of the dumbbell-shaped specimen (501); The mechanical loading assembly (40) includes a sliding guide rail, a driving motor, a lead screw (401), a pair of loading crossbeams (402), a fixture (403) and a mounting base (404). The lead screw (401) is installed in parallel on the mounting base (404). One end of the lead screw (401) is fixedly connected to the output shaft of the driving motor. The bottom of each loading crossbeam (402) is fixedly connected to a slider on the sliding guide rail. One end of each loading crossbeam (402) is sleeved on the lead screw (401) and is in threaded cooperation with the lead screw (401). The driving motor drives the lead screw (401) to rotate, thereby driving the loading crossbeam (402) to move along the axis direction of the lead screw (401). The other ends of the two loading crossbeams (402) fix the fixture (403), and the dumbbell-shaped specimen (501) is installed in the fixture (403); The temperature loading unit (41) includes a heat exchange plate support (410), a heat medium heat exchange plate (411), a sliding heat conduction seat (412), a sliding heat conduction seat support (413), a sliding heat conduction seat traction support (414), a compression screw (415), a rolling bearing (416), a sliding heat conduction block (417), a heat conduction copper bar (418) and a specimen heat conduction plate (419). The specimen heat conduction plate (419) is located on the fixture (403) and contacts the lower surface of the dumbbell-shaped specimen (501). The heat exchange plate support (410) is arranged between the heat medium heat exchange plate (411) and the mounting base (404) for supporting and fixing the heat medium heat exchange plate (411). The inner surfaces of the two sliding heat conduction blocks (417) are closely attached to the inner sides of the heat medium heat exchange plate (411) respectively. The two sliding heat conduction seats (412) are respectively fixedly connected to the corresponding sliding heat conduction blocks (417) through the sliding heat conduction seat supports (413). The rolling bearing (416) is installed in each sliding heat conduction seat (412), and under the pressing action of the compression screw (415), the rolling bearing (416) contacts the outer side surface of the heat medium heat exchange plate (411). The two ends of the heat conduction copper bar (418) are closely attached to the outer surface of the sliding heat conduction block (417) and the lower surface of the specimen heat conduction plate (419) in a plane contact manner respectively. Each sliding heat conduction seat support (413) is fixedly connected to the corresponding side of the loading cross beam (402) through the sliding heat conduction seat traction support (414). A heat medium channel is arranged inside the heat medium heat exchange plate (411), and the heat medium channel and the corrugated pipe (105) form a closed heat medium circulation loop. The corrugated pipe (105) is communicated with an external heat source through a heat conduction channel flange (104) on the cavity wall (101).

3. The resistivity testing device for solid propellants under thermo-mechanical coupling loading according to claim 1 or 2, characterized in that The microscopic imaging assembly (2) includes a high-speed camera (201), an imaging transparent window (202) and a distance adjustment support (203). A camera imaging flange (102) is arranged on the cavity wall (101) of the vacuum chamber (1) facing the dumbbell-shaped specimen (501). The imaging transparent window (202) is fixedly installed on the camera imaging flange (102). The high-speed camera (201) is connected to the cavity wall (101) through the distance adjustment support (203). The high-speed camera (201) observes and acquires the surface topography image of the dumbbell-shaped specimen (501) through the imaging transparent window (202).

4. The resistivity testing device for solid propellants under coupled thermal and mechanical loading according to claim 1 or 2, characterized in that The electronically controlled three-dimensional displacement platform (6) includes an X-direction displacement platform (601), a Y-direction displacement platform (602) and a Z-direction displacement platform (603), which are respectively used to adjust the lateral position, longitudinal position and vertical position of the dumbbell-shaped specimen (501) relative to the high-speed camera (201) in the microscopic imaging assembly (2).

5. The resistivity testing device for solid propellant under thermo-mechanical coupling loading according to claim 1 or 2, characterized in that, Each of the sliding heat conducting seats (412) is provided with two juxtaposed rolling bearings (416). The inner rings of the two rolling bearings (416) are fixedly connected by a connecting rod, and the pressing screw (415) fixedly connects the connecting rod to the side wall of the sliding heat conducting seat (412).

6. The resistivity testing device for solid propellant under coupled thermal and mechanical loading according to claim 1 or 2, characterized in that, The heat medium channel is a U-shaped channel. One end of the U-shaped channel is communicated with the heat medium input corrugated pipe, and the other end is communicated with the heat medium output corrugated pipe. Both the heat medium input corrugated pipe and the heat medium output corrugated pipe are communicated with the heat source through the heat conducting channel flange (104).

7. The resistivity testing device for solid propellants with coupled thermal and mechanical loading according to claim 1 or 2, characterized in that, Both ends of the heat medium heat exchange plate (411) are in contact with and fixedly connected to the two end parts of the heat exchange plate support (410).

8. The resistivity testing device for solid propellant with coupled mechanical and thermal loading according to claim 1 or 2, characterized in that, The force-heat coupling loading device (4) further includes a protective housing (7), and the protective housing (7) is arranged on the side of the force-heat coupling loading device (4) close to the lead screw (401).

9. A method for measuring the resistivity of a solid propellant under thermo-mechanical coupling loading, characterized in that, It includes the following steps: S1: Prepare the dumbbell-shaped specimen (501) and clean the probe extension copper wire (502); S2: Install the dumbbell-shaped specimen (501) in the fixture (403), connect the probe extension copper wire (502) to the probe base (3), and evacuate the vacuum chamber (1) to a preset vacuum degree; S3: Adjust the electric control three-dimensional displacement platform (6) so that the high-speed camera (201) in the microscopic imaging assembly (2) is aligned with the gauge section of the dumbbell-shaped specimen (501); S4: Start the temperature loading unit (41), adjust the temperature of the heat medium in the heat medium heat exchange plate (411) so that the temperature of the dumbbell-shaped specimen (501) reaches the target temperature and is kept warm for a preset duration; S5: Control the driving motor to rotate so that the fixture (403) uniformly stretches the dumbbell-shaped specimen (501) to the target length, and synchronously collect the surface topography image of the upper surface of the dumbbell-shaped specimen (501) during the stretching process by using the high-speed camera (201); S6: Measure and obtain the voltage value and current value corresponding to the gauge section of the dumbbell-shaped specimen (501) through the probe base (3), and calculate the resistivity of the solid propellant according to the measured voltage value and current value and the size parameters of the gauge section of the dumbbell-shaped specimen (501).

10. The resistivity test method of the solid propellant under coupled mechanical and thermal loading according to claim 9, wherein The preset vacuum degree is 0.5 Pa, and the preset duration is 30 min.

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