Solid propellant resistivity test device and test method using mechanical and thermal coupling loading

Abstract

The present invention relates to a solid propellant resistivity testing device and method using mechanical and thermal coupling loading, belonging to the field of resistivity testing technology, and solving the problem that traditional technologies cannot accurately measure the resistivity of solid propellants under mechanical and thermal coupling. The testing device includes a vacuum chamber, a microscopic imaging component, a probe holder, a mechanical and thermal coupling loading device, and an electrically controlled three-dimensional displacement platform. The mechanical and thermal coupling loading device includes a mechanical loading component and a temperature loading unit. A closed heat medium circulation loop formed by the temperature loading unit and a bellows is used to perform temperature loading on a dumbbell-shaped specimen. The dumbbell-shaped specimen is stretched using the mechanical loading component. The probe holder is connected to a probe measuring point inside the dumbbell-shaped specimen via a probe extension copper wire. The probe holder then applies electrical excitation to the dumbbell-shaped specimen, and finally measures and obtains test data for calculating the resistivity of the solid propellant. The device can accurately test the influence trend of the coupling of temperature and deformation on the resistivity of the solid propellant, with high repeatability.

Description

Technical Field

[0001] The present invention relates to the technical field of resistivity testing, and in particular to a solid propellant resistivity testing device and a testing method using mechanical and thermal coupling loading. Background Art

[0002] The development of electronically controlled solid propellants has overcome the technical bottlenecks of traditional solid propellants in terms of repeatable ignition and adjustable thrust. By applying a desired voltage to the electronically controlled solid propellant through electrodes, the propellant ignites and continues to burn without the need for ignition powder. When the voltage is removed, the propellant extinguishes, and reapplying the voltage will allow the propellant to burn again. Furthermore, by varying the applied voltage, the propellant's burning rate can be controlled, enabling thrust adjustment.

[0003] Solid propellant is a particle-reinforced energetic composite material composed of a polymer matrix and filler particles. Solid rocket motors are subject to various loads throughout their lifecycle, from manufacturing, transportation, handling, storage, and final launch. During long-term vertical storage, they are subjected to tensile and compressive stresses, which can easily cause irreversible deformation damage, resulting in internal holes and cracks in the propellant, affecting the overall resistivity of the solid propellant. During long-distance transportation across temperature zones, the solid propellant is subject to temperature swings, causing complex pyrolysis behavior and pyrolysis products, which can also cause changes in the propellant's resistivity. These resistivity changes caused by temperature and deformation seriously affect the ignition reliability and combustion performance of the solid rocket motor. Current research on solid propellants is limited to resistivity testing (see “H. Hu, Y. Ding, Study on combustion characteristics of ammonium perchlorateenhanced hydroxylamine nitrate-based electronically controlled solid propellant, Chemical Engineering Journal, 500 (2024) 157366”) or studying the electrical conductivity characteristics of solid propellants at different temperatures without mechanical loading (see “Bao Lirong et al. Thermal decomposition and electrical conductivity characteristics of HAN-based electronically controlled solid propellant [J]. Energetic Materials, 2019, Vol. 27, No. 9, pp. 743-748”). There is still a lack of testing equipment that can simultaneously apply temperature and mechanical loads to solid propellants and obtain the resistivity of solid propellants. Therefore, the development of a solid propellant resistivity testing device with coupled mechanical and thermal loading is of great significance. Summary of the Invention

[0004] The purpose of the present invention is to provide a solid propellant resistivity test device and test method with mechanical and thermal coupling loading, so as to solve the problem that traditional technology cannot accurately measure the resistivity of solid propellant under mechanical and thermal coupling. The test device and test method of the present invention utilize a closed heat medium circulation loop in a vacuum chamber composed of a temperature loading unit and a bellows to load the dumbbell-shaped specimen with temperature, utilize a mechanical loading assembly to stretch the dumbbell-shaped specimen, and connect the probe seat and the probe measuring point inside the dumbbell-shaped specimen through an extended copper wire of the probe. The probe seat then applies electrical excitation to the dumbbell-shaped specimen and measures to obtain test data for calculating the resistivity of the solid propellant. This can accurately test the influence trend of the coupling effect of temperature and deformation on the resistivity of the solid propellant, and provide an important technical means for exploring the effects of temperature and deformation on the ignition reliability and combustion control performance of the solid propellant.

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

[0006] Solid propellant resistivity test device with mechanical and thermal coupling loading, including:

[0007] Vacuum chamber, which is a vacuum environment when conducting resistivity testing;

[0008] A microscopic imaging assembly mounted on the vacuum chamber is used to capture surface topography images of a dumbbell-shaped specimen made of solid propellant. Probe measuring points are pre-buried at each end of the gauge section of the dumbbell-shaped specimen. Each probe measuring point is conductively 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. The probe extension copper wire bends as the dumbbell-shaped specimen is stretched.

[0009] A pair of probe holders mounted on the vacuum chamber via probe flanges, for applying electrical excitation to the dumbbell-shaped specimen and measuring test data for calculating the resistivity of the solid propellant, wherein one end of the two probe holders located inside the vacuum chamber is electrically connected to the exposed end of the corresponding probe extension copper wire;

[0010] A mechanical and thermal coupling loading device is provided in the vacuum chamber and is installed with the dumbbell-shaped specimen, and is used to synchronously apply a mechanical load and a temperature load to the dumbbell-shaped specimen;

[0011] An electrically controlled three-dimensional displacement platform is used to carry the mechanical and thermal coupling loading device and is fixed to the cavity wall of the vacuum chamber, and is used to adjust the relative position between the dumbbell-shaped specimen installed on the mechanical and thermal coupling loading device and the microscopic imaging assembly.

[0012] Accordingly, the present invention also proposes a solid propellant resistivity testing method using mechanical and thermal coupling loading, comprising the following steps:

[0013] S1: preparing the dumbbell-shaped specimen and cleaning the extended copper wire of the probe;

[0014] S2: Install the dumbbell-shaped specimen in the fixture, connect the extended copper wire of the probe to the probe holder, and evacuate the vacuum chamber to a preset vacuum degree;

[0015] S3: adjusting the electrically controlled three-dimensional displacement platform so that the high-speed camera in the microscopic imaging assembly is aligned with the gauge length section of the dumbbell-shaped specimen;

[0016] S4: starting the temperature loading unit to adjust the temperature of the heat medium in the heat medium heat exchange plate so that the temperature of the dumbbell-shaped sample reaches the target temperature and keeps the temperature for a preset time;

[0017] S5: controlling the driving motor to rotate so that the fixture stretches the dumbbell-shaped specimen to a target length at a uniform speed, and synchronously capturing a surface topography image of the upper surface of the dumbbell-shaped specimen during the stretching process using the high-speed camera;

[0018] S6: obtaining the voltage value and the current value corresponding to the gauge length section of the dumbbell-shaped sample by measuring with the probe base, and calculating the resistivity of the solid propellant according to the measured voltage value and current value and the dimensional parameters of the gauge length section of the dumbbell-shaped sample.

[0019] The beneficial effects of the present invention are as follows: through the mechanical and thermal coupling loaded solid propellant resistivity testing device of the present invention, the resistivity change trend of the solid propellant when the solid propellant is coupled with different temperature loads and different strain rates can be obtained. In the mechanical loading assembly, the probe measuring point embedded in the dumbbell-shaped specimen moves with the elongation of the specimen and is always located at the end of the specimen gauge section, ensuring the accuracy of the resistivity test. The temperature loading unit and the fixture are both dragged by the loading beam for linear motion, which can enable the dumbbell-shaped specimen to maintain a stable temperature loading during tensile loading, further ensuring the accuracy of the resistivity test. The temperature loading unit uses a thermal copper busbar to connect the sliding thermal block and the fixture. While ensuring stable heat conduction, it effectively avoids the mechanical load measurement deviation caused by rigid connection, thereby ensuring the accuracy of mechanical loading. The present invention comprehensively considers the influence of temperature stability in tensile loading, changes in the specimen resistivity test interval and mechanical load measurement accuracy on the accuracy of the resistivity test, making the test data more accurate and highly repeatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic diagram of the overall structure of a solid propellant resistivity testing device with mechanical and thermal coupling loading according to an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of the structure of the mechanical and thermal coupling loading device;

[0023] Figure 3 It is a schematic diagram of the cross-section enlarged structure of the temperature loading unit;

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

[0025] Description 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. Transparent imaging window; 203. Adjustable distance bracket;

[0027] 3. Probe seat;

[0028] 4. Mechanical and thermal coupling loading device;

[0029] 40. Mechanical loading assembly; 401. Lead screw; 402. Loading beam; 403. Clamp; 404. Mounting 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. Pressing screw; 416. Rolling bearing; 417. Sliding heat conduction block; 418. Heat conduction copper busbar; 419. Sample heat conduction plate;

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

[0032] 6. Electronically controlled three-dimensional displacement platform; 601, X-axis displacement platform; 602, Y-axis displacement platform; 603, Z-axis displacement platform;

[0033] 7. Protect the shell. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] See also Figures 1 to 4 The present embodiment provides a solid propellant resistivity testing device using mechanical and thermal coupling loading. The testing device mainly includes a vacuum chamber 1, a microscopic imaging assembly 2, a pair of probe holders 3, a mechanical and thermal coupling loading device 4 equipped with a solid propellant testing assembly 5, and an electrically controlled three-dimensional displacement platform 6. The solid propellant testing assembly 5 includes a dumbbell-shaped specimen 501 made of solid propellant, as well as a probe extension copper wire 502 and a probe measuring point 503. The probe measuring points 503 are pre-embedded in the two ends of the gauge section of the dumbbell-shaped specimen 501. Each probe measuring point 503 is conductively 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 to the outside for connection to the probe holder 3. The probe extension copper wire 502 is a flexible wire that bends as the dumbbell-shaped specimen 501 stretches to avoid introducing additional stress and ensure the accuracy of the resistivity test. The sample in this embodiment is designed to be dumbbell-shaped, which facilitates clamping the sample while providing a larger contact area at the sample end, thereby ensuring a more reliable sample clamping effect. However, it should be noted that the dumbbell-shaped sample 501 in this embodiment can also be implemented in other common shapes, such as a long strip, which are all within the scope of protection of the present invention.

[0036] The vacuum chamber 1 is a sealed, evacuable chamber. During resistivity testing, the interior of the chamber is in a vacuum. Multiple flange interfaces are provided on the chamber wall 101 of the chamber 1. These include a camera imaging flange 102, a probe flange 103, and a thermal channel flange 104. The camera imaging flange 102 is located on the chamber wall 101 opposite the dumbbell-shaped specimen 501 mounted on the mechanical loading assembly 40. A probe holder 3 is mounted on each of the two probe flanges 103. The thermal channel flange 104 is connected to the temperature loading unit 41 via a bellows 105. The thermal channel flange 104, the bellows 105, and the heat medium heat exchange plate 411 form a sealed flow channel.

[0037] The microscopic imaging assembly 2 is mounted on the vacuum chamber 1 and is used to capture surface topography images of the dumbbell-shaped specimen 501. Furthermore, the microscopic imaging assembly 2 includes a high-speed camera 201, a transparent imaging window 202, and a distance-adjustable bracket 203. The transparent imaging window 202 is fixedly mounted on the camera imaging flange 102, and the high-speed camera 201 is connected to the cavity wall 101 of the vacuum chamber 1 via the distance-adjustable bracket 203. The high-speed camera 201 observes and captures surface topography images of the dumbbell-shaped specimen 501 through the transparent imaging window 202, and transmits the captured surface topography images to subsequent image processing equipment for image processing and analysis.

[0038] After the probe base 3 is installed on the probe flange 103, the end of the probe base 3 located inside the vacuum chamber 1 is conductively connected to the end of the corresponding probe extension copper wire 502 exposed outside the dumbbell-shaped specimen 501. The two probe bases 3 are respectively conductively connected to the probe extension copper wire 502 on the corresponding side, thereby forming a current loop between the probe base 3, the probe extension copper wire 502 and the dumbbell-shaped specimen 501. Under the action of an external voltage source, the two probe bases 3 apply electrical excitation to the dumbbell-shaped specimen 501. At the same time, the probe bases 3 measure and obtain test data for calculating the resistivity of the solid propellant. The test data includes voltage and current values. Then, 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. , the specific calculation formula is as follows:

[0039] (1)

[0040] in, is the current voltage value applied at both ends of the gauge length segment, is the current value, is the current cross-sectional area of ​​the gauge segment, The current length of the gauge segment.

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

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

[0043] The mechanical and thermal coupling loading device 4 is arranged inside the vacuum chamber 1, and a dumbbell-shaped specimen 501 is installed on the mechanical and thermal coupling loading device 4, which is used to synchronously apply a mechanical load and a temperature load to the dumbbell-shaped specimen 501. Specifically, the mechanical and 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 drive motor, a screw 401, a pair of loading beams 402, a clamp 403 and a mounting base 404, wherein the screw 401 is installed in parallel on the mounting base 404, one end of the screw 401 is fixedly connected to the output shaft of the drive motor, and the other end is rotatably connected to a fixed plate on the mounting base 404, and the drive motor drives the screw 401 to rotate. The sliding guide rail is parallel to the lead screw 401 and is fixed to the mounting base 404. The bottom of each loading beam 402 is fixedly connected to the corresponding slider on the sliding guide rail. The loading beam 402 can slide along the sliding guide rail. At the same time, one end of each loading beam 402 is sleeved on the lead screw 401 and engages with the lead screw 401 thread. The drive motor drives the lead screw 401 to rotate, thereby driving the loading beam 402 to move along the axis of the lead screw 401. The other ends of the two loading beams 402 are fixed to the clamp 403, and the dumbbell-shaped specimen 501 is installed in the clamp 403. The temperature loading unit 41 is connected to the side wall of the loading beam 402 via the sliding thermal seat traction bracket 414. Therefore, the loading beam 402 can drag the clamp 403 and some components in the temperature loading unit 41 to move synchronously and at a constant speed.

[0044] The temperature loading unit 41 specifically includes a heat exchange plate bracket 410, a heat medium heat exchange plate 411, a sliding heat conductive seat 412, a sliding heat conductive seat bracket 413, a sliding heat conductive seat traction bracket 414, a clamping screw 415, a rolling bearing 416, a sliding heat conductive block 417, a heat conductive copper busbar 418, and a sample heat conductive plate 419. The sample heat conductive plate 419 is located on the fixture 403 and contacts the lower surface of the dumbbell-shaped sample 501 to transfer heat to the dumbbell-shaped sample 501. The heat exchange plate bracket 410 is disposed between the heat medium heat exchange plate 411 and the mounting base 404 to support and secure 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 bracket 410 and are fixedly connected via screws and mounting holes. The heat exchange plate bracket 410 simultaneously provides support and insulation, preventing heat from the heat medium heat exchange plate 411 from being directly transferred to other components. The inner surfaces of the two sliding heat-conducting blocks 417 are tightly fitted with the inner side surfaces of the heat medium heat exchange plate 411 respectively, and the two sliding heat-conducting seats 412 are fixedly connected to the corresponding sliding heat-conducting blocks 417 through the sliding heat-conducting seat brackets 413, and the clamping screws 415 are installed on the sliding heat-conducting seats 412 through threads. In each sliding heat-conducting seat 412, the rolling bearing 416 is pressed by the clamping screws 415, so that the rolling bearing 416 contacts the outer side surface of the heat medium heat exchange plate 411, ensuring that the sliding heat-conducting block 417 and the sliding heat-conducting seat 412 can slide on the two side surfaces of the heat medium heat exchange plate 411. Furthermore, 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 parallel rolling bearings 416 are provided in each sliding heat-conducting seat 412, and the inner rings of the two rolling bearings 416 are fixedly connected by a connecting rod. The clamping screw 415 is located at one end inside the sliding heat-conducting seat 412 and is threadedly connected to the connecting rod, thereby fixing the connecting rod to the side wall of the sliding heat-conducting seat 412. By rotating the clamping screw 415, the force between the rolling bearing 416 and the outer surface of the heat medium heat exchange plate 411 can be adjusted.

[0045] The ends of each heat-conducting copper busbar 418 fit tightly against the outer surface of the corresponding sliding heat-conducting block 417 and the lower surface of the sample heat-conducting plate 419, respectively, with planar contact to achieve close contact, thereby improving heat transfer efficiency. Each heat-conducting sliding seat bracket 413 is fixedly connected to the corresponding loading beam 402 via a heat-conducting sliding seat traction bracket 414, allowing the heat-conducting sliding seat 412, heat-conducting sliding seat bracket 413, heat-conducting sliding block 417, heat-conducting copper busbar 418, and sample heat-conducting plate 419 to move synchronously with the loading beam 402.

[0046] The heat medium heat exchange plate 411 is provided with a heat medium channel inside, and 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 connected to the heat medium channel inside the heat medium heat exchange plate 411, and the bellows 105 is connected to the heat medium channel inside the heat medium heat exchange plate 411 through the copper tube, forming a closed heat medium circulation loop. The bellows 105 is connected to the external heat source through the heat conduction channel flange 104 on the cavity wall 101, and the heat source provides the required heat medium and adjusts the temperature. The heat source can be implemented by a high and low temperature integrated machine, which heats the liquid through a heating rod or compresses the liquid with a compressor so that the silicone oil inside is heated or cooled. The heated or cooled liquid flows into the heat medium heat exchange plate 411 through the bellows 105 as a heat medium. The heat of the heat medium is finally transferred to the dumbbell-shaped sample 501 through the bellows 105, the heat medium heat exchange plate 411, the sliding heat conduction block 417, the heat conduction copper bar 418 and the sample heat conduction plate 419 in sequence. Furthermore, the shape of the heat medium channel can be a circuitous channel, including but not limited to an S-shape or a U-shape, and 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 connected to the heat medium input bellows, and the other end is connected to the heat medium output bellows. Both the heat medium input bellows and the heat medium output bellows are connected to the heat source through the heat conduction channel flange 104. The use of a U-shaped channel for the heat medium channel can extend the flow path of the heat medium within the heat medium heat exchange plate 411, thereby facilitating improved heat exchange efficiency.

[0047] Furthermore, the thermal-mechanical coupling loading device 4 also includes a protective shell 7, which is arranged on the side of the thermal-mechanical coupling loading device 4 close to the screw 401, and is used to partially cover the mechanical loading component 40 to avoid damage to the components during transportation, while also having dust-proof and aesthetic functions.

[0048] The working process of the testing device of 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 electrically controlled three-dimensional displacement platform 6 so that the high-speed camera 201 can clearly observe the gauge length section of the dumbbell-shaped specimen 501. The temperature loading unit 41 transfers heat to the dumbbell-shaped specimen 501 installed in the fixture 403. Then, the mechanical loading assembly 40 stretches the dumbbell-shaped specimen 501. At the same time, the probe holder 3 is used to apply electrical excitation and measure to obtain resistivity test data.

[0049] The solid propellant resistivity testing device with mechanical and thermal coupling loading proposed in this embodiment realizes the synchronous and precise loading of solid propellant with temperature and mechanical load under simulated real working conditions by integrating a vacuum chamber, a microscopic imaging component, a mechanical and thermal coupling loading device, and an electrically controlled three-dimensional displacement platform. The device utilizes pre-embedded probe measuring points and probe extension copper wires to collect electrical signals in real time, solving the problem of the inability to accurately measure the resistivity of solid propellant under mechanical and thermal coupling in traditional technologies. At the same time, the adoption of a surface contact design of a thermally conductive copper bar and a coordinated structure of a sliding thermal conductive block and a rolling bearing ensures the simultaneous improvement of heat conduction efficiency and mechanical loading stability under high temperature and high pressure environments. The vacuum environment isolates external interference, significantly improving the accuracy and repeatability of resistivity test data, and providing key technical support for the optimization of ignition reliability and precise thrust control of solid propellants.

[0050] In another embodiment, the present invention provides a solid propellant resistivity testing method using the test device described in the above embodiment using mechanical and thermal coupling loading, the method comprising the following steps:

[0051] S1: Using a sample cutter to cut the solid propellant blank to prepare a dumbbell-shaped sample 501, and cleaning the probe extension copper wire 502 to remove solid propellant waste adhering 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 until the vacuum level of the vacuum chamber 1 reaches a preset vacuum level, for example, 0.5 Pa;

[0053] S3: Adjust the electrically controlled three-dimensional displacement platform 6 so that the high-speed camera 201 in the microscopic imaging assembly 2 is aligned with the gauge length section of the dumbbell-shaped specimen 501. For example, first adjust the Z-axis displacement platform 603 so that the high-speed camera 201 can clearly observe the upper surface of the dumbbell-shaped specimen 501. Then, adjust the X-axis displacement platform 601 and the Y-axis displacement platform 602 respectively so that the high-speed camera 201 can observe the gauge length section of the upper surface of the dumbbell-shaped specimen 501.

[0054] S4: Start the temperature loading unit 41 to adjust the temperature of the heat medium in the heat medium heat exchange plate 411 so that the temperature of the dumbbell-shaped sample 501 reaches the target temperature and keeps the temperature for a preset time, for example, 30 minutes;

[0055] S5: Control the driving motor to rotate, thereby controlling the movement of the mechanical loading assembly 40, so that the clamp 403 stretches the dumbbell-shaped specimen 501 to the target length at a uniform speed, and synchronously captures the topographic image of the gauge length section of the dumbbell-shaped specimen 501 during the stretching process using the high-speed camera 201;

[0056] S6: The voltage and current values ​​corresponding to the gauge length section of the dumbbell-shaped sample 501 are measured by the probe holder 3. The resistivity of the solid propellant is then calculated based on the measured voltage and current values ​​and the dimensional parameters of the gauge length section of the dumbbell-shaped sample 501. The formula for calculating the resistivity of the solid propellant can be found in the previous formula (1) and will not be repeated here.

[0057] The solid propellant resistivity testing method with mechanical and thermal coupling loading proposed in this embodiment achieves accurate measurement of the resistivity change of solid propellant under mechanical and thermal coupling through steps such as sample pretreatment, vacuum treatment, sample morphology monitoring, temperature loading, synchronous control of mechanical deformation, and real-time electrical parameter acquisition. It breaks through the limitations of traditional single-factor testing and provides key technical support for the optimization of ignition reliability of solid propellant and precise thrust control.

[0058] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the scope of protection of the present invention.

Claims

1. A solid propellant resistivity test device with mechanical and thermal coupling loading, characterized in that: include: A vacuum chamber (1), wherein the interior of the chamber is a vacuum environment when performing resistivity testing; A microscopic imaging assembly (2) mounted on the vacuum chamber (1) is used to collect a surface topography image of a dumbbell-shaped sample (501) made of solid propellant, wherein probe measuring points (503) are pre-buried inside the two ends of the gauge section of the dumbbell-shaped sample (501), each of the probe measuring points (503) is conductively connected to one end of a corresponding probe extension copper wire (502), and the other end of each probe extension copper wire (502) extends out of the surface of the dumbbell-shaped sample (501) and is exposed to the outside, and the probe extension copper wire (502) bends as the dumbbell-shaped sample (501) is stretched; A pair of probe bases (3) mounted on the vacuum chamber (1) via probe flanges (103) are used to apply electrical excitation to the dumbbell-shaped specimen (501) and measure and obtain test data for calculating the resistivity of the solid propellant, wherein one end of the two probe bases (3) located inside the vacuum chamber (1) is electrically connected to one end of the corresponding probe extension copper wire (502) exposed to the outside; a mechanical-thermal coupling loading device (4) disposed in the vacuum chamber (1) and mounted with the dumbbell-shaped specimen (501), for synchronously applying a mechanical load and a temperature load to the dumbbell-shaped specimen (501); an electrically controlled three-dimensional displacement platform (6) for carrying the thermomechanical coupling loading device (4) and fixed to the cavity wall (101) of the vacuum chamber (1), and for adjusting the relative position between the dumbbell-shaped specimen (501) mounted on the thermomechanical coupling loading device (4) and the microscopic imaging assembly (2); The mechanical-thermal coupling loading device (4) comprises 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), wherein the mechanical loading assembly (40) comprises a sliding guide rail, a drive motor, a lead screw (401), a pair of loading beams (402), a clamp (403) and a mounting base (404), wherein the lead screw (401) is mounted parallel to the mounting base (404), and one end of the lead screw (401) is connected to the output shaft of the drive motor. Fixedly connected, the bottom of each loading beam (402) is fixedly connected to the slider on the sliding guide rail, one end of each loading beam (402) is sleeved on the lead screw (401) and is threadedly engaged with the lead screw (401), the driving motor drives the lead screw (401) to rotate and thereby drives the loading beam (402) to move along the axial direction of the lead screw (401), the other ends of the two loading beams (402) are fixed to 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 bracket (410), a heat medium heat exchange plate (411), a sliding heat conductive seat (412), a sliding heat conductive seat bracket (413), a sliding heat conductive seat traction bracket (414), a clamping screw (415), a rolling bearing (416), a sliding heat conductive block (417), a heat conductive copper bar (418) and a sample heat conductive plate (419), wherein the sample heat conductive plate (419) is located on the fixture (403) and contacts the lower surface of the dumbbell-shaped specimen (501), and the heat exchange plate bracket (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 conductive blocks (417) are respectively tightly fitted with the inner side surfaces of the heat medium heat exchange plate (411), and the two sliding heat conductive seats (412) are respectively connected to the opposite sides through the sliding heat conductive seat bracket (413). The corresponding sliding heat-conducting block (417) is fixedly connected, and the rolling bearing (416) is installed in each sliding heat-conducting seat (412). Under the pressing action of the clamping screw (415), the rolling bearing (416) contacts the outer side surface of the heat medium heat exchange plate (411), and the two ends of the heat-conducting copper bar (418) are tightly fitted to the outer surface of the sliding heat-conducting block (417) and the lower surface of the sample heat-conducting plate (419) in a planar contact manner. Each sliding heat-conducting seat bracket (413) is fixedly connected to the loading beam (402) on the corresponding side through the sliding heat-conducting seat traction bracket (414). A heat medium channel is provided inside the heat medium heat exchange plate (411), and the heat medium channel and the bellows (105) form a closed heat medium circulation loop. The bellows (105) is connected to the external heat source through the heat-conducting channel flange (104) on the cavity wall (101).

2. The solid propellant resistivity testing device with mechanical and thermal coupling loading according to claim 1, characterized in that: The microscopic imaging assembly (2) comprises a high-speed camera (201), an imaging transparent window (202) and a distance-adjustable bracket (203); a camera imaging flange (102) is provided on the cavity wall (101) of the vacuum chamber (1) facing the dumbbell-shaped specimen (501); the imaging transparent window (202) is fixedly mounted on the camera imaging flange (102); the high-speed camera (201) is connected to the cavity wall (101) via the distance-adjustable bracket (203); and the high-speed camera (201) observes and collects a surface morphology image of the dumbbell-shaped specimen (501) through the imaging transparent window (202).

3. The solid propellant resistivity testing device with mechanical and thermal coupling loading according to claim 1, characterized in that: The electrically controlled three-dimensional displacement platform (6) includes an X-axis displacement platform (601), a Y-axis displacement platform (602), and a Z-axis displacement platform (603), which are respectively used to adjust the lateral position, longitudinal position, and vertical position of the dumbbell-shaped sample (501) relative to the high-speed camera (201) in the microscopic imaging assembly (2).

4. The solid propellant resistivity testing device with mechanical and thermal coupling loading according to claim 1, characterized in that: Two parallel rolling bearings (416) are provided in each sliding heat-conducting seat (412), and the inner rings of the two rolling bearings (416) are fixedly connected via a connecting rod, and the clamping screw (415) fixes the connecting rod to the side wall of the sliding heat-conducting seat (412).

5. The solid propellant resistivity testing device with mechanical and thermal coupling loading according to claim 1, characterized in that: The heat medium channel is a U-shaped channel, one end of the U-shaped channel is connected to the heat medium input bellows, and the other end is connected to the heat medium output bellows, and both the heat medium input bellows and the heat medium output bellows are connected to the heat source through the heat conduction channel flange (104).

6. The solid propellant resistivity testing device with mechanical and thermal coupling loading according to claim 1, characterized in that: Both ends of the heat medium heat exchange plate (411) are in contact with and fixedly connected to the two end portions of the heat exchange plate bracket (410).

7. The solid propellant resistivity testing device with mechanical and thermal coupling loading according to claim 1, characterized in that: The force-heat coupling loading device (4) further comprises a protective shell (7), wherein the protective shell (7) is arranged on a side of the force-heat coupling loading device (4) close to the lead screw (401).

8. A solid propellant resistivity testing method based on the mechanical and thermal coupling loading of the device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: preparing the dumbbell-shaped specimen (501) and cleaning 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: adjusting the electrically controlled three-dimensional displacement platform (6) so that the high-speed camera (201) in the microscopic imaging assembly (2) is aligned with the gauge length section of the dumbbell-shaped specimen (501); S4: starting the temperature loading unit (41) to adjust the temperature of the heat medium in the heat medium heat exchange plate (411) so that the temperature of the dumbbell-shaped sample (501) reaches the target temperature and is kept warm for a preset time; S5: controlling the driving motor to rotate so that the clamp (403) stretches the dumbbell-shaped specimen (501) to a target length at a uniform speed, and synchronously collecting a surface morphology image of the upper surface of the dumbbell-shaped specimen (501) during the stretching process using the high-speed camera (201); S6: The probe holder (3) is used to measure and obtain the voltage value and current value corresponding to the gauge length section of the dumbbell-shaped sample (501), and the resistivity of the solid propellant is calculated based on the measured voltage value and current value and the size parameters of the gauge length section of the dumbbell-shaped sample (501).

9. The solid propellant resistivity testing method using mechanical and thermal coupling loading according to claim 8, characterized in that: The preset vacuum degree is 0.5 Pa, and the preset time is 30 minutes.

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