Efficient in-situ testing device for mechanical and thermal coupling of solid propellants in scanning electron microscopes

Abstract

The present invention relates to an efficient in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope, belonging to the technical field of precision scientific instruments and material micromechanical properties testing, and solves the problem that the current in-situ testing equipment of scanning electron microscopes cannot construct a stable temperature field for solid propellant samples that undergo large deformation. The present invention includes: a mechanical loading component for applying a mechanical load to the solid propellant sample; a load loading measurement component, arranged on a loading beam, for measuring the mechanical load of the solid propellant sample; a liquid circulation heat conduction component, for continuously transferring the heat of the circulating heat conduction medium to the solid propellant sample following the movement of the two loading beams, thereby applying a stable heat load; a vacuum circulation pipe component, for forming a closed-loop heat transfer channel; and a pipe telescopic component, for adjusting the imaging position of the main body of the in-situ testing device in the scanning electron microscope cabin. The present invention realizes mechanical and thermal coupling loading and precise load measurement of solid propellants.

Description

Technical Field

[0001] The present invention relates to the technical field of precision scientific instruments and material micromechanical performance testing, and in particular to a high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope. Background Art

[0002] Solid propellant is not only the energy source of solid rocket engines but also a key engineering component. Because solid propellant is a viscoelastic material, its mechanical properties are dependent not only on the loading rate but also on the ambient temperature of the service environment. Under complex mechanical loads and temperature loading over a wide temperature range, solid propellant is highly susceptible to microscopic defect growth and mechanical property degradation.

[0003] Scanning electron microscopy (SEM) offers advantages such as a large depth of field, a wide field of view, excellent stereoscopic imaging, and infinitely adjustable magnification, making it widely used for characterizing material microstructures. Consequently, many researchers use SEM to image fracture surfaces of solid propellants subjected to various loads, such as temperature and strain rate. This post-hoc analysis method can only partially infer the cause of propellant fracture based on fracture morphology, but fails to reveal the failure mechanism during loading. Combining SEM with in situ tensile testing techniques, however, can reveal the microscopic failure patterns of propellants during loading. Currently, in situ testing equipment used for mechanical property testing of solid propellant specimens under SEM often only applies a single mechanical load and is unable to generate a stable temperature field for specimens undergoing large deformations. Creating a service environment within an SEM where mechanical and temperature loading are coupled is crucial for revealing the structure-property relationship between the macroscopic mechanical properties and microscopic damage evolution of solid propellants. Therefore, developing an efficient in situ testing device for mechanical and thermal coupling of solid propellants within an SEM is of great significance. Summary of the Invention

[0004] The purpose of the present invention is to provide an efficient in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope to solve the problems existing in the above-mentioned prior art. The device controls the mechanical loading of the solid propellant sample through a mechanical loading component. During the mechanical loading process, the heat in the circulating heat-conducting medium is transferred to the sliding-attached heat-conducting component through the liquid circulating heat-conducting component. The sliding-attached heat-conducting component moves with the loading beam and synchronously realizes contact heat conduction. Finally, the heat is transferred to the solid propellant sample through the load loading measurement component, realizing mechanical and thermal coupling loading and material mechanical property testing of the solid propellant sample, providing an important technical means for revealing the failure mechanism of the propellant under mechanical and thermal coupling.

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

[0006] An efficient in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope comprises a pipe expansion and contraction assembly connected to the scanning electron microscope cabin and an in-situ testing device body located within the scanning electron microscope cabin. The in-situ testing device body comprises a mechanical loading assembly, a vacuum circulation pipe assembly, a load loading measurement assembly, and a liquid circulation heat conduction assembly.

[0007] The mechanical loading component is used to apply a mechanical load to the solid propellant sample;

[0008] The load loading and measuring assembly is arranged on the two loading beams of the mechanical loading assembly, and is used to clamp the solid propellant sample and measure the mechanical load of the solid propellant sample using a force sensor;

[0009] The liquid circulation heat conduction component is used to follow the movement of the two loading beams to continuously transfer the heat of the circulating heat conduction medium to the solid propellant sample, thereby applying a stable heat load to the solid propellant sample;

[0010] The vacuum circulation pipeline assembly includes a vacuum bellows located in the scanning electron microscope cabin, and the vacuum bellows is respectively connected to the liquid circulation heat conduction assembly and the external circulation pipeline in the pipeline expansion assembly to form a closed-loop heat transfer channel;

[0011] The pipeline telescopic assembly is fixed on the cabin wall of the scanning electron microscope and is used to adjust the imaging position of the in-situ testing device body in the cabin of the scanning electron microscope by driving the displacement of the vacuum bellows while maintaining the vacuum degree of the scanning electron microscope.

[0012] The present invention proposes an efficient in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope, which has the following beneficial effects: the efficient in-situ testing device of the present invention can synchronously construct tensile loads of different strain rates and temperature loads in a wide temperature range for solid propellants in a scanning electron microscope, can continuously and stably apply temperature loads to solid propellants during tensile loading, and cooperate with the scanning electron microscope to carry out multi-scale mechanical property tests on solid propellants under mechanical and thermal coupling, providing a dedicated and efficient testing device for in-situ testing of the mechanical properties of solid propellants under the influence of service temperature, and providing important testing characterization equipment for in-depth revelation of the deformation, damage and failure mechanism of solid propellants under mechanical and thermal coupling. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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.

[0014] Figure 1 This is a schematic diagram of the overall structure of the high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to an embodiment of the present invention installed in a scanning electron microscope;

[0015] Figure 2 This is a schematic diagram of the overall structure of the high-efficiency in-situ testing device;

[0016] Figure 3 It is a schematic diagram of the overall structure of the liquid circulation heat conduction component;

[0017] Figure 4 This is a schematic diagram of the installation and connection structure of the liquid circulation heat conduction component;

[0018] Figure 5 for Figure 4 A partial enlarged schematic diagram of the middle 4A area;

[0019] Figure 6 is a structural diagram of the load measurement component;

[0020] Figure 7 This is a schematic diagram of the overall structure of the pipeline telescopic component.

[0021] Explanation of Reference Numerals: 1. Pipe telescopic assembly; 11. Cam-type telescopic pipe assembly; 111. Locking nut; 112. Sliding traction seat; 113. Sliding guide column; 114. Rotating cam; 115. Guide cylinder; 116. Disc-type bellows; 117. Bellows flange; 12. External circulation pipe; 121. Compression fitting; 122. Flange-through pipe; 123. Circulation pipe flange;

[0022] 2. SEM cabin; 21. Pole shoe; 22. Beveled rectangular flange;

[0023] 3. Main body of the in-situ testing device;

[0024] 31. Mechanical loading assembly; 311. Bidirectional trapezoidal lead screw; 312. Loading beam; 313. Displacement measurement assembly; 314. Drive assembly;

[0025] 32. Vacuum circulation pipe assembly; 321. Pipe fixing seat; 322. Vacuum bellows; 323. Vacuum pipe joint; 324. Thermal insulation connection seat;

[0026] 33. Load measurement assembly; 331. Load measurement assembly; 3311. Force sensor fixing plate; 3312. Force sensor; 3313. Fixture positioning plate; 3314. Round nut; 3315. Hexagonal lock nut; 332. Fixture assembly; 3321. Anti-frost fixture cover; 3322. Thermal conductive upper cover; 3323. Thermal conductive fillet; 3324. Thermal insulation fixture base; 3325. High thermal conductivity connector; 3326. Solid bracket; 333. Solid propellant sample;

[0027] 34. Liquid circulation heat conduction assembly; 341. Heat input assembly; 3411. Liquid circulation heat conduction plate; 3412. Heat conduction plate fixing bracket; 3413. Heat conduction plate fixing slide; 3414. Protective shell; 342. Heat conduction support assembly; 3421. Heat insulation mounting body; 3422. Heat insulation slide; 3423. Friction heat conduction plate; 343. Sliding attachment heat conduction assembly; 3431. Sliding traction bracket; 3432. First sliding heat conduction block bracket; 3433. First clamping slider; 3434. First light rod bearing; 3435. Sliding heat conduction cover; 3436. Sliding heat conduction seat; 3437. Vacuum thermal grease; 344. Central fixed heat conduction assembly; 3441. Central sliding heat conduction seat; 3442. Central heat conduction positioning block; 3443. Central adjustable heat conduction plate. DETAILED DESCRIPTION

[0028] 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.

[0029] like Figures 1 to 7 As shown, the present invention provides an efficient in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope, comprising a pipe telescopic assembly 1 and an in-situ testing device body 3, wherein the pipe telescopic assembly 1 is fixedly connected to the bulkhead of the scanning electron microscope cabin 2 through an oblique rectangular flange 22, and the in-situ testing device body 3 is located in the scanning electron microscope cabin 2.

[0030] The in-situ test device body 3 includes a mechanical loading component 31, a vacuum circulation pipe component 32, a load loading measurement component 33, and a liquid circulation heat conduction component 34. The mechanical loading component 31 is used to apply a stable mechanical load to the solid propellant sample 333; the load loading measurement component 33 is set on two loading beams 312 in the mechanical loading component 31, and is used to clamp the solid propellant sample 333 and use the force sensor 3312 to measure the mechanical load of the solid propellant sample 333; the liquid circulation heat conduction component 34 is used to follow the movement of the two loading beams to circulate the heat conduction medium The heat of the mass is continuously transferred to the solid propellant sample, applying a stable thermal load to the solid propellant sample; the vacuum circulation pipe assembly 32 includes a vacuum bellows 322 located in the scanning electron microscope cabin 2, and the vacuum bellows 322 are respectively connected to the liquid circulation heat conduction assembly 34 and the external circulation pipe 12 in the pipe expansion assembly 1 to form a closed-loop heat transfer channel; the pipe expansion assembly 1 is fixed on the cabin wall of the scanning electron microscope, and is used to adjust the imaging position of the in-situ test device body 3 in the scanning electron microscope cabin 2 by driving the vacuum bellows 322 to move under the premise of maintaining the vacuum degree of the scanning electron microscope.

[0031] The mechanical loading assembly 31 includes two loading beams 312 and a bidirectional trapezoidal screw 311 threadedly engaged with the two loading beams 312. The bidirectional trapezoidal screw 311 drives the two loading beams 312 toward each other, thereby driving the load loading and measurement assembly 33 thereon to move, thereby applying a tensile load to the solid propellant sample 333 clamped in the load loading and measurement assembly 33. The bidirectional trapezoidal screw 311 is driven by a drive assembly 314, which utilizes a servo motor and a worm gear mechanism to drive the bidirectional trapezoidal screw 311. Simultaneously, the displacement measurement assembly 313 measures the travel distance between the two loading beams 312 in real time. For example, the displacement measurement assembly 313 can use a grating scale and a grating readhead disposed in each of the two loading beams 312 to measure the travel distance, thereby more accurately controlling the mechanical load applied to the solid propellant sample 333.

[0032] The load loading and measuring assembly 33 includes a load measuring assembly 331 and a pair of clamp assemblies 332 installed in the loading beam 312 . The pair of clamp assemblies 332 are fixedly connected to the two loading beams 312 respectively.

[0033] Each clamp assembly 332 includes a thermally conductive top cover 3322, a thermally insulating clamp seat 3324, a high thermal conductivity connecting seat 3325 and a mounting seat, wherein one end of the high thermal conductivity connecting seat 3325 with high thermal conductivity is installed in the thermally insulating clamp seat 3324 with low thermal conductivity through a small boss, and the high thermal conductivity connecting seat 3325 and the thermally conductive top cover 3322 respectively wrap the lower surface and the upper surface of the clamping end of the solid propellant sample 333. The clamp assembly 332 can transfer heat to the solid propellant sample 333. A mounting seat is provided on one side of the thermally insulating clamp seat 3324, and the clamp assembly 332 is connected to the corresponding loading beam 312 through the mounting seat.

[0034] Furthermore, each clamp assembly 332 also includes an anti-frost clamp cover 3321, which is made of a polyimide material with a low thermal conductivity coefficient and is installed on the upper surface of the thermal conductive upper cover 3322. It can prevent frost from forming on the upper surface of the thermal conductive upper cover 3322 during low-temperature loading, thereby affecting the imaging effect of the scanning electron microscope.

[0035] Each fixture assembly 332 also includes a pair of thermally conductive fillets 3323 , each of which has the same curvature as the fillet of the solid propellant sample 333 and is installed in a high thermal conductivity connection seat 3325 to apply load and transfer heat to the fillet of the solid propellant sample 333 .

[0036] Each clamp assembly 332 also includes a solid bracket 3326, which is installed on the upper surface of the insulation clamp seat 3324. The solid bracket 3326 has good rigidity and is used to increase the rigidity of the insulation clamp seat 3324 to prevent the insulation clamp seat 3324 from deforming during mechanical loading.

[0037] Load measurement assembly 331 includes a force sensor mounting plate 3311, a force sensor 3312, a fixture positioning plate 3313, a round nut 3314, and a hexagonal locking nut 3315. The small-pitch end of the hexagonal locking nut 3315 is externally threaded to connect to one of the mounting bases of fixture assembly 332, while the large-pitch end of the hexagonal locking nut 3315 is internally threaded to connect to one end of force sensor 3312. The other end of force sensor 3312 passes through a through-hole in force sensor mounting plate 3311 and is fixedly connected to round nut 3314, thereby axially securing force sensor 3312 to force sensor mounting plate 3311. Force sensor 3312 is used to measure the tensile load of solid propellant sample 333 and has a certain temperature compensation function. Optionally, force sensor 3312 can use a WMC series sensor from Interface with a range of 45N. The fixture positioning plate 3313 can determine the rotation angle of the fixture. The two ends of the fixture positioning plate 3313 are connected to the force sensor fixing plate 3311 and the mounting seat in the fixture assembly 332, respectively. The mounting seat is cylindrical, and the side of the cylinder has a flat surface that contacts the fixture positioning plate 3313. This surface is used to determine the required rotational angle between the fixture positioning plate 3313 and the fixture. Once the fixture positioning plate 3313 is properly installed, the relative angle between the force sensor 3312 and the fixture assembly 332 is fixed, preventing the fixture from rotating relative to the force sensor 3312 during mechanical loading tests. The load measurement assembly 331, in conjunction with the fixture assembly 332, can accurately measure the millinewton-level mechanical load of the solid propellant sample 333.

[0038] The liquid circulation heat conduction component 34 includes a heat input component 341 , a heat conduction support component 342 , a sliding attachment heat conduction component 343 and a central fixed heat conduction component 344 .

[0039] The heat input assembly 341 includes a liquid circulation heat conducting plate 3411, a heat conducting plate fixing frame 3412 and a heat conducting plate fixing groove 3413 installed in a group on the heat insulation installation body 3421, wherein the interior of the liquid circulation heat conducting plate 3411 is provided with a flow channel connected to the vacuum bellows 322, the heat conducting plate fixing frame 3412 provides support for the liquid circulation heat conducting plate 3411, and the heat conducting plate fixing frame 3412 installed with screws can slide up and down along the heat conducting plate fixing groove 3413, and the heat conducting plate fixing frame 3412 is fixed to the heat conducting plate fixing groove 3413 by screws, thereby fitting and pressing the liquid circulation heat conducting plate 3411 to the friction heat conducting plate 3423, so that the liquid circulation heat conducting plate 3411 can transfer heat in the circulating medium to the friction heat conducting plate 3423.

[0040] Furthermore, the heat input component 341 also includes a protective shell 3414, which is installed on the upper surface of the heat conduction plate fixing groove 3413 to prevent foreign matter, dust, etc. from invading the liquid circulation heat conduction component 34.

[0041] The heat-conducting support assembly 342 includes a heat-insulating mounting body 3421, a heat-insulating slide 3422 and a friction heat-conducting plate 3423, wherein the inner groove of the heat-insulating slide 3422 is embedded with the friction heat-conducting plate 3423, and the outer frame of the heat-insulating slide 3422 is connected to the internal positioning surface of the heat-insulating mounting body 3421 through threads.

[0042] The liquid circulation heat conduction assembly 34 comprises two sets of synchronously sliding, attached heat conduction assemblies 343 and a central fixed heat conduction assembly 344. Both the sliding, attached heat conduction assemblies 343 and the central fixed heat conduction assembly 344 comprise a compression slider mounted with two sets of polished rod bearings and a sliding heat conduction block bracket. The polished rod bearings are threadedly connected to the lower surfaces of the corresponding compression sliders and contact the thermal insulation grooves 3422. In the sliding-attached heat-conducting assembly 343, the first sliding heat-conducting block bracket 3432 is threadedly connected to the first pressing slider 3433 and the sliding heat-conducting seat 3436 on both sides. This allows the sliding heat-conducting seat 3436 to be pressed against the surface of the friction heat-conducting plate 3423, which transfers heat to the sliding heat-conducting seat 3436. The sliding traction bracket 3431 is fixedly connected to the first sliding heat-conducting block bracket 3432 and the loading beam 312, respectively. The loading beam 312 can pull the sliding-attached heat-conducting assembly 343 to slide linearly against the surface of the friction heat-conducting plate 3423. The sliding heat-conducting seat 3436 and the sliding heat-conducting cover 3435 form a space that covers the end of the high-thermal-conductivity connecting seat 3325 that is not holding the solid propellant sample 333. The first polished rod bearing 3434 is threadedly connected to the lower surface of the first pressing slider 3433 and contacts the thermal insulation groove 3422. In the central fixed heat-conducting component 344, the two sides of the second sliding heat-conducting block bracket are respectively connected to the second clamping slider and the central sliding heat-conducting seat 3441 through threads, which can press the central sliding heat-conducting seat 3441 against the surface of the friction heat-conducting plate 3423. The friction heat-conducting plate 3423 transfers heat to the central sliding heat-conducting seat 3441, and the central sliding heat-conducting seat 3441 is connected to the central heat-conducting positioning block 3442. The upper surface of the central heat-conducting positioning block 3442 is connected to the central sliding heat-conducting seat 3441 in the central fixed heat-conducting component 344, and its lower surface is installed in the groove of the heat-insulating mounting body 3421. The central heat-conducting positioning block 3442 is used to determine the relative position of the central fixed heat-conducting component 344 and the heat-insulating mounting body 3421. The central adjustable heat conducting plate 3443 is mounted in a groove on the central sliding heat conducting seat 3441. The upper surface of the central adjustable heat conducting plate 3443 contacts the solid propellant sample 333, transferring heat from the central sliding heat conducting seat 3441 to the solid propellant sample 333. The second polished rod bearing is threadedly connected to the lower surface of the second compression slider and contacts the thermal insulation groove 3422.

[0043] Furthermore, a gap of approximately 0.5 mm exists between the high-thermal-conductivity connector 3325 and the sliding thermal-conducting cover 3435 and sliding thermal-conducting base 3436. This gap can compensate for the slight deformation of the force sensor 3312 caused by the force. At the same time, the gap is filled with vacuum thermal grease 3437, thereby more efficiently transferring heat from the sliding-attached thermal-conducting component 343 to the high-thermal-conductivity connector 3325. By adopting a heat conduction method that combines sliding friction heat conduction with the flexible filling heat conduction of thermal grease in series, heat is transferred to the high-thermal-conductivity fixture assembly, effectively improving the device's thermal load capacity while ensuring the accuracy of mechanical load measurement.

[0044] The vacuum circulation pipe assembly 32 includes a pipe fixing seat 321, a vacuum bellows 322, a vacuum pipe joint 323 and an insulating connection seat 324, wherein one end of the vacuum bellows 322 is connected to the flow channel inside the liquid circulation heat conduction plate 3411 through the vacuum pipe joint 323, and the vacuum bellows 322 is fixedly connected to the insulating connection seat 324 through the pipe fixing seat 321, and the other end of the vacuum bellows 322 is connected to the external circulation pipe 12 installed in the pipe expansion assembly 1. On the one hand, the liquid circulation heat conduction component 34 is connected to the loading beam 312 of the mechanical loading component 31 through threads, and on the other hand, it is flexibly connected to the high thermal conductivity connection seat 3325 of the clamp component 332 in the load loading measurement component 33 through pressurized flowable vacuum thermal grease 3437. The circulating heat conduction medium flows through the external circulation pipe 12, the vacuum circulation pipe component 32 and the liquid circulation heat conduction component 34 in turn, and completes heat exchange through convection heat transfer in the heat input component 341, and inputs heat into the in-situ test device body 3. The heat is transferred to the solid propellant sample 333 through contact heat conduction between the thermal support component 342, the sliding attached thermal conduction component 343, and the middle fixed thermal conduction component 344. The in-situ test device can still load a stable heat load on the solid propellant sample 333 through contact heat conduction during the stretching process of the mechanical loading component 31 on the solid propellant sample 333.

[0045] The pipe telescopic assembly 1 is used to adjust the imaging position of the in-situ testing device body 3 connected to the terminal end of the vacuum bellows 322 in the cabin of the scanning electron microscope over a large range. It specifically includes a cam-type telescopic pipe assembly 11 and an external circulation pipe 12.

[0046] The cam-type telescopic pipe assembly 11 includes a locking nut 111, a sliding traction seat 112, a sliding guide post 113, a rotating cam 114, and a guide cylinder 115. The liquid circulation heat conducting plate 3411 and the flanged pipe 122 in the heat input assembly 341 are both connected to the vacuum bellows 322 via a vacuum pipe joint 323. The sliding guide post 113 is simultaneously mounted in the spiral groove of the rotating cam 114 and the linear groove of the guide cylinder 115. The sliding guide post 113 is threadedly connected to the sliding traction seat 112 located within the rotating cam 114. The sliding traction seat 112 and the sliding guide post 113 are circumferentially connected by threads. The sliding traction seat 112 is axially connected to the circulation pipe flange 123. The sliding guide post 113 also contacts both the spiral groove of the rotating cam 114 and the linear groove of the guide cylinder 115. The rotating cam 114 can rotate and make the circulation pipe flange 123 slide linearly along the inner wall of the guide cylinder 115. The linearly sliding circulation pipe flange 123 can drag the vacuum bellows 322 and the in-situ testing device body 3 toward or away from the electron microscope cabin wall.

[0047] The locking nut 111 is threadedly connected to the guide cylinder 115. Rotating the locking nut 111 can adjust the sliding friction between the rotating cam 114 and the guide cylinder 115, thereby locking the circumferential position of the rotating cam 114 and further locking the relative position between the rotating cam 114 and the guide cylinder 115.

[0048] When the rotating cam 114 is rotated, the sliding guide column 113 slides along the tangential direction of the spiral groove of the rotating cam 114 while still maintaining tangential sliding along the linear groove of the guide cylinder 115. The sliding guide column 113 moves linearly along the slot of the guide cylinder 115, and drives the connected sliding traction seat 112, circulation pipe flange 123 and vacuum bellows 322 to move linearly along the axis of the guide cylinder 115.

[0049] Furthermore, the pipe expansion and contraction assembly 1 also includes a disc-shaped bellows 116 and a bellows flange 117. The circulation pipe flange 123 is connected to one end of the disc-shaped bellows 116 to seal the disc-shaped bellows 116. The other end of the disc-shaped bellows 116 is welded to the bellows flange 117, and the bellows flange 117 is fixedly connected to the beveled rectangular flange 22. The disc-shaped bellows 116 is connected to the scanning electron microscope chamber 2 through the bellows flange 117, creating a vacuum environment with the scanning electron microscope chamber 2. During movement, the disc-shaped bellows 116 is stretched / compressed, but the vacuum level inside the scanning electron microscope chamber is always maintained. The function of the disc-type bellows 116 is to ensure the vacuum inside the scanning electron microscope cabin 2 while allowing the vacuum bellows 322 to have a certain amount of moving space. The vacuum bellows 322 does not need to be directly connected to the cabin wall of the scanning electron microscope cabin 2, thereby realizing a large range of adjustment of the imaging position of the in-situ test device body 3 in the scanning electron microscope cabin 2.

[0050] The present invention aims to provide an efficient in-situ testing device for mechanical and thermal coupling of solid propellants within a scanning electron microscope (SEM), addressing the problem in existing SEM in-situ testing equipment that can only apply a single mechanical load to a solid propellant sample and cannot establish a stable temperature field for a solid propellant sample that undergoes large deformation. The efficient in-situ testing device comprises a pipe expansion and contraction assembly and an in-situ testing device body. The in-situ testing device body comprises a mechanical loading assembly, a vacuum circulation pipe assembly, a load loading and measurement assembly, and a liquid circulation thermal conductivity assembly. The imaging position of the in-situ testing device body within the SEM can be adjusted over a wide range by rotating a rotating cam in the pipe expansion and contraction assembly. The load loading and measurement assembly is mounted on the end loading crossbeam of the mechanical loading assembly and is used to apply tensile loading to the solid propellant sample and accurately obtain millinewton-level mechanical loads. The liquid circulation thermal conductivity assembly utilizes a heat conduction method that combines sliding friction heat conduction with thermal grease flexible filling heat conduction in series to transfer heat to a high-thermal-conductivity fixture assembly, effectively improving the device's thermal load-bearing capacity while ensuring the accuracy of mechanical load measurement. This efficient in-situ testing device has excellent mechanical and thermal coupling loading and precise load measurement capabilities for solid propellants with low modulus and low thermal conductivity.

[0051] The high-efficiency in-situ testing device of the present invention can synchronously construct tensile loads of different strain rates and temperature loads in a wide temperature range for solid propellants in a scanning electron microscope, can continuously and stably apply temperature loads to solid propellants during tensile loading, and cooperate with the scanning electron microscope to carry out multi-scale mechanical property tests on solid propellants under the action of mechanical and thermal coupling, providing a dedicated and efficient testing device for in-situ testing of the mechanical properties of solid propellants under the influence of service temperature, and providing important testing characterization equipment for in-depth revelation of the deformation, damage and failure mechanism of solid propellants under mechanical and thermal coupling.

[0052] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An efficient in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope, characterized by: The invention comprises a pipeline expansion and contraction assembly (1) connected to a scanning electron microscope cabin (2) and an in-situ testing device body (3) located in the scanning electron microscope cabin (2), wherein the in-situ testing device body (3) comprises a mechanical loading assembly (31), a vacuum circulation pipeline assembly (32), a load loading measurement assembly (33) and a liquid circulation heat conduction assembly (34); The mechanical loading component (31) is used to apply a mechanical load to the solid propellant sample (333); The load loading measurement assembly (33) is arranged on two loading beams (312) of the mechanical loading assembly (31), and is used to clamp the solid propellant sample (333) and measure the mechanical load of the solid propellant sample (333) using a force sensor (3312); The liquid circulation heat conduction component (34) is used to follow the movement of the two loading beams (312) to continuously transfer the heat of the circulating heat conduction medium to the solid propellant sample (333), thereby applying a stable heat load to the solid propellant sample (333); The liquid circulation heat conduction component (34) comprises a heat input component (341), a heat conduction support component (342), two sets of sliding attachment heat conduction components (343) and a central fixed heat conduction component (344); The heat input assembly (341) comprises a liquid circulation heat conducting plate (3411), a heat conducting plate fixing frame (3412) and a heat conducting plate fixing chute (3413) mounted in a group on a heat-insulating mounting body (3421); a flow channel communicating with a vacuum bellows (322) is provided inside the liquid circulation heat conducting plate (3411); the heat conducting plate fixing frame (3412) for supporting the liquid circulation heat conducting plate (3411) can slide up and down along the heat conducting plate fixing chute (3413) and be fixed to the heat conducting plate fixing chute (3413) by screws, so that the liquid circulation heat conducting plate (3411) is pressed and connected to the friction heat conducting plate (3423) in the heat conducting support assembly (342); The heat-conducting support assembly (342) comprises a heat-insulating mounting body (3421), a heat-insulating chute (3422) and a friction heat-conducting plate (3423); the inner groove of the heat-insulating chute (3422) is embedded with the friction heat-conducting plate (3423); and the outer frame of the heat-insulating chute (3422) is connected to the inner positioning surface of the heat-insulating mounting body (3421) via threads; Each group of the sliding attached heat conducting components (343) includes a sliding traction bracket (3431), a first sliding heat conducting block bracket (3432), a first pressing slider (3433), a first light rod bearing (3434), a sliding heat conducting cover (3435) and a sliding heat conducting seat (3436). The two sides of the first sliding heat conducting block bracket (3432) are respectively connected to the first pressing slider (3433) and the sliding heat conducting seat (3436) by screw threads, and the sliding heat conducting seat (3436) is pressed against the surface of the friction heat conducting plate (3423). The friction heat conducting plate (3423) conducts heat to the sliding heat conducting seat (3436) and the middle fixed heat conducting component (344). The middle sliding heat-conducting seat (3441) and the sliding traction bracket (3431) are fixedly connected to the first sliding heat-conducting block bracket (3432) and the loading beam (312) respectively. The sliding heat-conducting seat (3436) and the sliding heat-conducting cover (3435) form a space covering the end of the high-heat-conducting connecting seat (3325) that does not clamp the sample. There is a gap between the high-heat-conducting connecting seat (3325) and the sliding heat-conducting cover (3435) and the sliding heat-conducting seat (3436), and the gap is filled with vacuum heat-conducting grease (3437). The first polished rod bearing (3434) is connected to the lower surface of the first pressing slider (3433) by a thread and contacts the heat-insulating slide groove (3422). The vacuum circulation pipe assembly (32) includes a vacuum bellows (322) located in the scanning electron microscope cabin (2), and the vacuum bellows (322) is respectively connected to the liquid circulation heat conduction assembly (34) and the external circulation pipe (12) in the pipe expansion and contraction assembly (1), forming a closed-loop heat transfer channel; The pipeline expansion assembly (1) is fixed on the wall of the scanning electron microscope and is used to adjust the imaging position of the in-situ testing device body (3) in the scanning electron microscope cabin (2) by driving the vacuum bellows (322) to move while maintaining the vacuum degree of the scanning electron microscope.

2. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 1, characterized in that: The mechanical loading assembly (31) comprises two loading beams (312) and a bidirectional trapezoidal screw (311) threadedly engaged with the two loading beams (312), and the bidirectional trapezoidal screw (311) drives the two loading beams (312) to move toward each other.

3. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 1 or 2, characterized in that: The load loading measurement assembly (33) includes a load measurement assembly (331) and a pair of clamp assemblies (332), wherein the pair of clamp assemblies (332) are fixedly connected to the two loading beams (312) respectively; Each of the fixture components (332) includes a heat-conducting upper cover (3322), a heat-insulating fixture seat (3324), a high-thermal-conductivity connecting seat (3325) and a mounting seat. One end of the high-thermal-conductivity connecting seat (3325) is mounted in the heat-insulating fixture seat (3324), and the high-thermal-conductivity connecting seat (3325) and the heat-conducting upper cover (3322) respectively wrap the lower surface and the upper surface of the clamping end of the solid propellant sample (333). A mounting seat is provided on one side of the heat-insulating fixture seat (3324) and is connected to the corresponding loading beam (312) through the mounting seat. The load measurement assembly (331) comprises a force sensor fixing plate (3311), a force sensor (3312), a fixture positioning plate (3313), a round nut (3314) and a hexagonal locking nut (3315). The small-pitch end of the hexagonal locking nut (3315) is externally threadedly connected to a mounting seat of one of the fixture assemblies (332). The large-pitch end of the hexagonal locking nut (3315) is internally threadedly connected to one end of the force sensor (3312). The other end of the force sensor (3312) passes through a through hole on the force sensor fixing plate (3311) and is fixedly connected to the round nut (3314). The two ends of the fixture positioning plate (3313) are respectively connected to the force sensor fixing plate (3311) and the mounting seat.

4. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 3, characterized in that: The clamp assembly (332) further includes an anti-frost clamp cover (3321) mounted on the upper surface of the heat-conducting upper cover (3322).

5. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 3, characterized in that: The central fixed heat-conducting assembly (344) includes a second sliding heat-conducting block bracket, a second pressing slider, a second light rod bearing, a central sliding heat-conducting seat (3441), a central heat-conducting positioning block (3442) and a central adjustable heat-conducting plate (3443). The two sides of the second sliding heat-conducting block bracket are respectively connected to the second pressing slider and the central sliding heat-conducting seat (3441) by threads. The second light rod bearing is connected to the lower surface of the second pressing slider by threads and contacts the heat-insulating slide groove (3422). The central sliding heat-conducting seat (3441) is connected and matched with the central heat-conducting positioning block (3442) installed in the groove of the heat-insulating installation body (3421). The central adjustable heat-conducting plate (3443) is installed in the groove on the central sliding heat-conducting seat (3441), and the upper surface of the central adjustable heat-conducting plate (3443) contacts the solid propellant sample (333).

6. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 5, characterized in that: The heat input assembly (341) further comprises a protective shell (3414) mounted on the upper surface of the heat conducting plate fixing slot (3413).

7. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 5, characterized in that: The vacuum circulation pipe assembly (32) comprises a pipe fixing seat (321), a vacuum bellows (322), a vacuum pipe joint (323) and a heat-insulating connecting seat (324); one end of the vacuum bellows (322) is in communication with the flow channel inside the liquid circulation heat conduction plate (3411) via the vacuum pipe joint (323), and is fixedly connected to the heat-insulating connecting seat (324) via the pipe fixing seat (321); the other end of the vacuum bellows (322) is in communication with an external circulation pipe (12) installed in the pipe expansion and contraction assembly (1).

8. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 1 or 2, characterized in that: The pipeline telescopic assembly (1) comprises a cam-type telescopic pipeline assembly (11) and an external circulation pipeline (12); The cam-type telescopic pipe assembly (11) comprises a locking nut (111), a sliding traction seat (112), a sliding guide post (113), a rotating cam (114) and a guide cylinder (115); the sliding guide post (113) is simultaneously installed in the spiral groove of the rotating cam (114) and the linear groove of the guide cylinder (115); the sliding guide post (113) is connected to the sliding traction seat (112) located in the rotating cam (114) through a thread; the sliding traction seat (112) is fixedly connected to the circulation pipe flange (123) in the external circulation pipe (12) in the axial direction; the locking nut (111) is connected to the guide cylinder (115) through a thread and is used to lock the relative position of the rotating cam (114) and the guide cylinder (115); The external circulation pipeline (12) comprises a sleeve-type pipe joint (121), a flange-penetrating pipeline (122) and a circulation pipeline flange (123). One end of the flange-penetrating pipeline (122) is communicated with the vacuum bellows (322), and the other end passes through the circulation pipeline flange (123) and is then installed with the sleeve-type pipe joint (121).

9. The high-efficiency in-situ testing device for mechanical and thermal coupling of solid propellants in a scanning electron microscope according to claim 8, characterized in that: The pipeline expansion assembly (1) further comprises a disc-type bellows (116) and a bellows flange (117); one end of the disc-type bellows (116) is fixedly connected to the circulation pipeline flange (123); the other end is connected to the bellows flange (117) by welding, and the bellows flange (117) is fixedly connected to the oblique angle rectangular flange (22).

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