Solid propellant mechanical property testing device and method compatible with SEM (scanning electron microscope) and CT (computed tomography)

Abstract

The invention relates to an SEM (scanning electron microscope) and CT (computed tomography) compatible solid propellant mechanical property testing device and method, belongs to the technical field of precise scientific instruments and material micro-mechanical property testing, and solves the problems that in the prior art, due to the fact that imaging equipment is single, and image quality becomes poor due to creeping accumulation, micro-scale failure information of propellants is incomplete and inaccurate to obtain. In the mechanical property testing device, the in-situ mechanical testing device performs mechanical loading and load holding on the propellant sample, the SEM obtains the surface appearance of the propellant sample, the double-source double-probe industrial CT obtains the internal three-dimensional structure of the propellant sample, and the in-situ mechanical testing device is transmitted between the transfer cabin main cavity and the electron microscope cabin through the transfer channel. And the vacuum transfer cabin containing the in-situ mechanical testing device is transferred between the transfer channel and the scanning turntable of the double-source double-probe industrial CT by the mechanical arm. According to the invention, more comprehensive and accurate mesoscopic failure information of the propellant sample can be obtained while less time cost is paid.

Description

Technical Field

[0001] The present invention relates to the technical field of precision scientific instruments and micro-mechanical property testing of materials, and particularly to a device and method for testing the mechanical properties of solid propellants compatible with SEM and CT. Background Art

[0002] During the research and development of solid propellants, in-situ testing of mechanical properties is a key link for evaluating their reliability and stability. The Scanning Electron Microscope (SEM), as a high-resolution imaging technology, is widely used for observing surface topography. It can provide very detailed images of the sample surface structure for analyzing the microscopic features of the material surface. Computed Tomography (CT) is a non-destructive imaging technology based on X-rays that can provide three-dimensional images of the internal structure of the sample. Based on the above characteristics, a variety of in-situ mechanical property testing devices compatible with scanning electron microscopes or Micro-CT have been developed at home and abroad, but these devices can only be compatible with one imaging device.

[0003] These two imaging technologies, SEM and CT, each have their own advantages and disadvantages, and it is difficult to quickly obtain complete information of the propellant sample simultaneously in the same test. SEM can only obtain the surface information of the sample and cannot reveal the internal structural features of the sample, especially when observing internal defects and microcracks in the sample. CT technology is suitable for revealing macroscopic defects inside the sample, such as pores and cracks. However, CT requires a long time for scanning and imaging. For the propellant during the mechanical loading process, during the long-time and multiple CT scans, the propellant is prone to obvious creep accumulation effects, resulting in serious image overlap in the obtained three-dimensional images and unable to obtain real three-dimensional topography information. Therefore, using SEM or CT alone often cannot comprehensively reflect the micro-mechanical properties of the propellant sample.

[0004] If it is possible to synchronously and in-situ collect the surface topography information and internal three-dimensional structural features of the solid propellant under mechanical load, and combine the obtained surface topography changes and internal damage evolution for comprehensive analysis, it is of great significance for revealing the mechanism between the macroscopic mechanical properties and mesoscopic damage, failure, and deformation of the propellant at multiple levels and dimensions. Therefore, the research on a device and test method for testing the mechanical properties of solid propellants compatible with SEM and CT synchronously is of great significance. Summary of the Invention

[0005] The object of the present invention is to provide a testing device and method for the mechanical properties of solid propellants compatible with SEM and CT, so as to solve the problems in the above-mentioned existing technologies, such as incomplete and inaccurate acquisition of mesoscopic failure information of propellants due to single imaging equipment and deteriorated image quality caused by creep accumulation. The present invention constructs a connection channel between a scanning electron microscope and a dual-source dual-detector industrial CT through a vacuum transfer chamber and a transfer channel, and realizes the adjustment of the specimen angle through two sets of rotatable jigs that rotate synchronously, which can simultaneously meet the various imaging angles required by different imaging modes of the scanning electron microscope and the requirement that the specimen needs to rotate following the scanning angle during the scanning process of the dual-source dual-detector industrial CT, and can quickly and completely obtain the surface and internal deformation and damage forms of the propellant specimen during the whole loading process, providing a key technical means for scientifically constructing the relationship between the mesoscopic tissue evolution and the macroscopic property dynamic response of solid propellants from the surface to the interior under complex loadings.

[0006] In order to achieve the above object, the present invention adopts the following solutions:

[0007] A testing device for the mechanical properties of solid propellants compatible with SEM and CT, the testing device includes:

[0008] A scanning electron microscope, provided with a transfer channel communicating with the electron microscope chamber of the scanning electron microscope, for obtaining the surface morphology information of the propellant specimen;

[0009] A dual-source dual-detector industrial CT, for obtaining the internal three-dimensional structure information of the propellant specimen;

[0010] A vacuum transfer chamber, including a transfer chamber door, a transfer chamber main cavity, a transfer chamber scanning window bracket and a high-transparency scanning window. A moving platform for transmitting the in-situ mechanical testing device is arranged inside the transfer chamber main cavity. The high-transparency scanning window is installed on the side wall of the transfer chamber main cavity through the transfer chamber scanning window bracket. The transfer chamber door is connected to the front end of the transfer chamber main cavity, and is used to control the combination and isolation of the transfer chamber main cavity and the transfer channel;

[0011] A robotic arm, for transporting the vacuum transfer chamber containing the in-situ mechanical testing device along a predetermined spatial motion trajectory between the docking position of the transfer channel and the scanning turntable of the dual-source dual-detector industrial CT, and the vacuum transfer chamber maintains a high-vacuum environment during the transportation process;

[0012] A transfer channel, provided with a vacuum pneumatic flap valve for controlling the connection and isolation of the transfer channel, and is used to transmit the in-situ mechanical testing device between the transfer chamber main cavity and the electron microscope chamber;

[0013] In-situ mechanical testing device, including a bidirectional mechanical loading platform and two groups of rotatable clamps installed on the bidirectional mechanical loading platform. Both ends of the propellant sample are fixedly clamped on the two rotatable clamps respectively. The two groups of rotatable clamps, under the cooperation of the bidirectional mechanical loading platform, perform stretching and / or rotating actions synchronously according to the scanning imaging rhythm of the scanning electron microscope and the dual-source dual-detector industrial CT, including synchronous co-rotation, synchronous counter-rotation, asynchronous co-rotation, and asynchronous counter-rotation, to perform mechanical loading and load holding on the propellant sample.

[0014] Meanwhile, the present invention also proposes a method for testing the mechanical properties of solid propellants compatible with SEM and CT. The testing method includes the following steps:

[0015] S1: The robotic arm transports the vacuum transfer chamber to the docking position of the transfer channel, opens the transfer chamber door and the vacuum pneumatic flap valve, connects the vacuum transfer chamber to the scanning electron microscope, and extracts the vacuum degrees of the scanning electron microscope, the transfer channel, and the vacuum transfer chamber to a preset vacuum degree and maintains it;

[0016] S2: Determine the loading form for testing the mechanical properties of the propellant sample. If it is an in-situ tensile test, set the active frameless torque motor and the slave torque motor to the master-slave following mode; if it is a tensile-torsion test, control the active frameless torque motor and the slave torque motor to run independently;

[0017] S3: Turn on the electron gun of the scanning electron microscope and locate the test target area of the propellant sample;

[0018] S4: Set the loading parameters for the mechanical property test. The in-situ mechanical testing device completes the loading of the target parameters and maintains the load without unloading;

[0019] S5: Judge whether it is a SEM / EDS / DIC test. If so, the active frameless torque motor and the slave torque motor synchronously rotate the two groups of rotatable clamps to the first deflection angle state; if not, continue to judge whether it is an EBSD test. If so, the active frameless torque motor and the slave torque motor adjust the two groups of rotatable clamps to the second deflection angle state. After adjusting the imaging angle, the scanning electron microscope obtains the microscopic morphology information on the surface of the test target area;

[0020] S6: Judge whether the mechanical property test in the scanning electron microscope is completed. If so, transfer the in-situ mechanical testing device to the vacuum transfer chamber through the transfer channel, and transport the propellant sample to below the high-transparency scanning window through the mobile platform inside the vacuum transfer chamber. Close the transfer chamber door and the vacuum pneumatic flap valve in sequence. After venting the vacuum of the low-vacuum section of the transfer channel, the robotic arm transports the vacuum transfer chamber to the scanning turntable in the dual-source dual-detector industrial CT;

[0021] S7: Synchronize the scanning frequency of the ray source in the dual-source dual-detector industrial CT and the rotation speed of the two sets of rotatable jigs in the in-situ mechanical testing device. The X-rays emitted by the ray source penetrate the high-transparency scanning window and the propellant sample and then irradiate the CT detector to obtain the internal three-dimensional structure information during the rotation scanning process of the propellant sample;

[0022] S8: After the dual-source dual-detector industrial CT scanning and imaging are completed, determine whether the mechanical property test inside the dual-source dual-detector industrial CT is finished. If so, the robotic arm transports the vacuum transfer chamber to dock with the transfer channel on the scanning electron microscope, opens the transfer chamber door and the vacuum pneumatic flap valve to establish a vacuum channel between the vacuum transfer chamber, the transfer channel and the scanning electron microscope, and transports the in-situ mechanical testing device into the scanning electron microscope through the transfer channel;

[0023] S9: Determine whether the combined mechanical property test between the scanning electron microscope and the dual-source dual-detector industrial CT is finished. If so, vent the vacuum of the scanning electron microscope and replace the propellant sample; if not, return to step S3 until the combined mechanical property test is completed.

[0024] The present invention has the following beneficial effects compared with the prior art:

[0025] In view of the disadvantages of existing in-situ mechanical property testing devices that can only be singly compatible with scanning electron microscopes or CTs, which can only obtain surface information in a short sampling time and internal information in a long sampling time during testing, but the image quality is poor due to creep, the present invention provides a propellant mechanical property testing device and testing method that are synchronously compatible with scanning electron microscopes and CTs. During the mechanical loading and holding process, the in-situ mechanical testing device is wrapped in a vacuum turret. By utilizing the flexibility and convenience of the robotic arm, the in-situ mechanical testing device can be quickly transferred between the scanning electron microscope and the dual-source dual-detector industrial CT. The sealed vacuum turret avoids the number and time of repeated vacuum pumping of the scanning electron microscope when the in-situ mechanical testing device switches imaging devices. The two sets of rotatable clamps in the testing device can adjust the imaging angle of the propellant specimen according to different imaging methods of the scanning electron microscope, and can also adjust the angle of the propellant specimen in real time following the scanning frequency of the radiation source in the dual-source dual-detector industrial CT. Through the testing device and testing method designed by the present invention, the optimal sampling time interval and number ratio for image acquisition using the scanning electron microscope and CT can be set. By taking advantage of the fast imaging feature of the scanning electron microscope, a large amount of surface topography information of the specimen can be obtained. At the same time, by taking advantage of the feature that CT scanning can obtain the internal three-dimensional structure information of the specimen, only a small amount of accurate information about the internal structure damage evolution form of the surface failure area can be obtained. While completely obtaining the surface and internal failure forms of the propellant specimen, the influence of stress relaxation on the mechanical properties of the propellant specimen is effectively avoided, ensuring the accuracy of the material mechanical property testing, and providing a novel and effective technical means for scientifically establishing the relationship between the mesoscopic tissue evolution and the macroscopic mechanical property dynamic response of the propellant under complex load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 FIG. is a schematic diagram of the overall structure of the solid propellant mechanical property testing device compatible with SEM and CT according to the embodiment of the present invention;

[0028] Figure 2 is Figure 1 a partial enlarged schematic diagram after removing the transfer cabin scanning window bracket and the high-transparency scanning window in the 1A area in FIG.;

[0029] Figure 3 a schematic diagram of the overall structure of the in-situ mechanical testing device;

[0030] Figure 4 isFigure 3 Internal cross-sectional view of area 7A;

[0031] Figure 5 Schematic diagram of the overall structure of the in-situ mechanical testing device for microscopic imaging and transfer transportation in the SEM;

[0032] Figure 6 is Figure 5 Partial enlarged schematic diagram of area 4A;

[0033] Figure 7 Schematic diagram of the overall structure of the in-situ mechanical testing device in the vacuum transfer chamber;

[0034] Figure 8 Schematic diagram of the in-situ mechanical testing device for three-dimensional imaging in cooperation with a dual-source and dual-detector industrial CT;

[0035] Figure 9 Flow chart of the method for testing the mechanical properties of solid propellants compatible with SEM and CT according to another embodiment of the present invention.

[0036] Explanation of reference numerals:

[0037] 1. Vacuum transfer chamber; 101. Transfer chamber door; 102. Main cavity of the transfer chamber; 103. X-direction moving platform of the transfer chamber; 104. Y-direction moving platform of the transfer chamber; 105. Scanning window bracket of the transfer chamber; 106. High-transparency scanning window;

[0038] 2. Transfer channel; 201. High-vacuum section transfer channel; 202. Low-vacuum section transfer channel;

[0039] 3. Vacuum pneumatic gate valve;

[0040] 4. Scanning electron microscope; 401. EBSD detector; 402. EDS detector; 403. Pole shoe;

[0041] 5. Dual-source and dual-detector industrial CT; 51. CT detector; 52. Scanning turntable; 53. Radiation source; 531. Micro-focus radiation source;

[0042] 6. Manipulator;

[0043] 7. In-situ mechanical testing device; 701. Loading crossbeam; 702. Bidirectional trapezoidal lead screw; 703. Active frameless torque motor; 7031. Motor hollow rotor; 7032. Motor stator; 7033. Motor stator fixing seat; 704. Encoder; 705. Slip ring; 706. Force sensor; 7061. Force sensor main body for measuring force; 7062. Force sensor signal line; 707. Needle roller bearing; 708. Active fixture head; 709. Propellant sample; 710. Driven fixture head; 711. Thrust ball bearing; 712. Driven torque motor. Specific Embodiment

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] As Figures 1 to 8 shown, this embodiment provides a mechanical property testing device for solid propellants that is compatible with SEM and CT. The testing device includes a vacuum transfer chamber 1, a transfer channel 2, a scanning electron microscope 4, a dual-source dual-detector industrial CT 5, a robotic arm 6, and an in-situ mechanical testing device 7.

[0046] The scanning electron microscope 4 is used to obtain the surface morphology information of the propellant sample 709, and a transfer channel 2 communicating with the electron microscope chamber is provided on the side wall of the electron microscope chamber of the scanning electron microscope 4.

[0047] The dual-source dual-detector industrial CT 5 is used to obtain the internal three-dimensional structure information of the propellant sample 709.

[0048] Furthermore, the dual-source dual-detector industrial CT 5 in this embodiment includes a frame and a CT detector 51, a scanning turntable 52, and a radiation source 53 provided on the frame. The scanning turntable 52 for supporting the sample is located between the CT detector 51 and the radiation source 53, and the CT detector 51 and the radiation source 53 are symmetrically arranged with respect to the scanning turntable 52. When the vacuum transfer chamber 1 including the in-situ mechanical testing device 7 is located on the scanning turntable 52, the moving platform in the main chamber 102 of the transfer chamber moves the propellant sample 709 clamped in the in-situ mechanical testing device 7 below the high-transparency scanning window 106, so that the X-rays emitted by the radiation source 53 penetrate the high-transparency scanning window 106 and the propellant sample 709 and irradiate the CT detector 51, presenting clear microscopic structure information in the CT detector 51. Optionally, the radiation source 53 can adopt a micro-focus radiation source 531 to further improve the scanning resolution and reduce creep accumulation.

[0049] The vacuum transfer cabin 1 includes a transfer cabin door 101, a main transfer cabin cavity 102, a transfer cabin scanning window bracket 105, and a high-transparency scanning window 106. Inside the main transfer cabin cavity 102, there is a moving platform for transporting the in-situ mechanical testing device 7, including an X-direction moving platform 103 and a Y-direction moving platform 104 of the transfer cabin. The high-transparency scanning window 106 is installed on the side wall of the main transfer cabin cavity 102 through the transfer cabin scanning window bracket 105. The transfer cabin door 101 is connected to the front end of the main transfer cabin cavity 102 and is used to control the combination and isolation of the main transfer cabin cavity 102 and the transfer channel 2. Among them, the X-direction moving platform 103 and the Y-direction moving platform 104 of the transfer cabin have the same structure, and their interiors are all composed of a servo motor, a linear guide rail, a trapezoidal lead screw, a movable bottom plate, etc. Their connection and operation principle are: the servo motor is connected to the trapezoidal lead screw, the movable bottom plate is installed on the trapezoidal lead screw and the linear guide rail, and the rotation of the servo motor drives the trapezoidal lead screw to rotate, thereby driving the movable bottom plate to slide along the linear guide rail. The X-direction moving platform 103 and the Y-direction moving platform 104 of the transfer cabin are used in combination, and under the control of the system control and data acquisition and processing unit, the movement of the in-situ mechanical testing device 7 in the main transfer cabin cavity 102 can be realized. The X-direction and Y-direction in the X-direction moving platform 103 and the Y-direction moving platform 104 of the transfer cabin are the same as the x-axis and y-axis directions in the Figure 1 xyz coordinate system, where the x-axis is along the length direction of the dual-source dual-detector industrial CT 5, the y-axis is along the width direction of the dual-source dual-detector industrial CT 5, and the z-axis is along the height direction of the dual-source dual-detector industrial CT 5.

[0050] The robotic arm 6 is used to transfer the vacuum transfer cabin 1 containing the in-situ mechanical testing device 7 between the docking position of the transfer channel 2 and the scanning turntable 52 of the dual-source dual-detector industrial CT 5 according to a predetermined spatial motion trajectory. And the vacuum transfer cabin 1 maintains a high-vacuum environment during the transfer process. The transfer process of the in-situ mechanical testing device 7 is realized while maintaining the propellant sample 709 in a high-vacuum and stable mechanical load process.

[0051] As an optional way to realize the connection between the robotic arm 6 and the vacuum transfer cabin 1, a suction cup is installed at the end of the robotic arm 6. The suction cup is connected to the side wall of the vacuum transfer cabin 1 using the principle of vacuum negative pressure, so as to realize a stable connection to the vacuum transfer cabin 1 during the transfer process of the vacuum transfer cabin 1.

[0052] The transfer channel 2 is provided with a vacuum pneumatic gate valve 3 for controlling the connection and isolation of the transfer channel 2, and is used to transfer the in-situ mechanical testing device 7 between the main cavity 102 of the transfer cabin and the electron microscope cabin. The vacuum transfer cabin 1 is connected to the electron microscope cabin of the scanning electron microscope 4 through the vacuum pneumatic gate valve 3 and the transfer channel 2. The vacuum pneumatic gate valve 3 divides the transfer channel 2 into a high-vacuum section transfer channel 201 and a low-vacuum section transfer channel 202. The high-vacuum section transfer channel 201 is directly connected to the electron microscope cabin, and the vacuum degree of the low-vacuum section transfer channel 202 is regulated by the vacuum pneumatic gate valve 3. The vacuum pneumatic gate valve 3 can establish a channel between the low-vacuum section transfer channel 202 and the high-vacuum section transfer channel 201. The in-situ mechanical testing device 7 can be transported from the electron microscope cabin to the vacuum transfer cabin 1 or from the vacuum transfer cabin 1 to the electron microscope cabin through the transfer channel 2.

[0053] The in-situ mechanical testing device 7 is used to apply tensile and / or rotational mechanical loads to the solid propellant specimen 709 and measure the magnitude of the load. It specifically includes a bidirectional mechanical loading platform and two groups of rotatable clamps installed on the bidirectional mechanical loading platform. And the two groups of rotatable clamps can rotate synchronously in the same direction, synchronously in the opposite direction, asynchronously in the same direction or asynchronously in the opposite direction around the common axis of the clamps during the loading process of the bidirectional mechanical loading platform. The two ends of the propellant specimen 709 are respectively fixed and clamped on the two rotatable clamps. The two groups of rotatable clamps can follow the scanning imaging rhythm of the scanning electron microscope 4 and the dual-source dual-detector industrial CT 5 under the cooperation of the bidirectional mechanical loading platform, that is, perform tensile and / or rotational actions synchronously according to the scanning imaging rhythm of the scanning electron microscope 4 and the dual-source dual-detector industrial CT 5. The rotational action can be any one of synchronous rotation in the same direction, synchronous rotation in the opposite direction, asynchronous rotation in the same direction and asynchronous rotation in the opposite direction, so as to realize mechanical loading and load holding of the propellant specimen 709. The scanning imaging rhythm of the scanning electron microscope 4 and the dual-source dual-detector industrial CT 5 refers to the imaging steps and time pre-determined during the mechanical property test of the solid propellant. For example: First, the in-situ mechanical testing device 7 performs tensile on the propellant specimen 709. After the tensile stops, the mechanical load is kept without unloading, and the scanning electron microscope is used for imaging; after obtaining the image, the in-situ mechanical testing device 7 is transferred to the dual-source dual-detector industrial CT 5 (the mechanical load remains unchanged). The rotatable clamps in the in-situ mechanical testing device 7 rotate at a set rotational speed, and the dual-source dual-detector industrial CT 5 obtains a complete image of the propellant specimen 709 rotating one week according to the set CT shooting time; after the CT imaging is completed, the in-situ mechanical testing device 7 is transferred to the scanning electron microscope again. The in-situ mechanical testing device 7 performs tensile loading on the propellant specimen 709 again. After the loading is completed, the scanning electron microscope is used for imaging again. Thus, a complete imaging process including multiple scanning imaging rhythms is completed. The specific scanning imaging rhythm varies according to different mechanical property test requirements and is not limited here.

[0054] The bidirectional mechanical loading platform includes a bidirectional trapezoidal lead screw 702 and two loading crossbeams 701 that are in threaded engagement with the bidirectional trapezoidal lead screw 702. Two sets of rotatable clamps are respectively connected to the two loading crossbeams 701. The bidirectional trapezoidal lead screw 702 drives the loading crossbeams 701 to drive the rotatable clamps thereon to perform a stretching motion, thereby realizing the tensile loading of the propellant specimen 709.

[0055] Furthermore, the two sets of rotatable clamps are divided into an active rotary tensile clamp and a driven rotary tensile clamp. The active rotary tensile clamp includes an active frameless torque motor 703, a large-aperture encoder 704, a slip ring 705, a force sensor 706, a needle roller bearing 707, a thrust ball bearing, and an active clamp head 708. The active frameless torque motor 703 includes a motor hollow rotor 7031, a motor stator 7032, and a motor stator fixing seat 7033. The force sensor 706 includes a force sensor force-measuring body 7061 and a force sensor signal wire 7062. One end of the force sensor force-measuring body 7061 is connected in the motor hollow rotor 7031. The motor hollow rotor 7031 is connected to the corresponding loading crossbeam 701 through a thrust ball bearing. The force sensor signal wire 7062 passes through the motor hollow rotor 7031 and is connected to the slip ring 705 installed at the end of the encoder 704. This design of the signal wire extending from the tail of the sensor and cooperating with the slip ring can avoid the phenomenon that the signal wire is broken due to excessive winding during the rotation of the clamp. The motor stator 7032 is installed on the motor stator fixing seat 7033. The encoder 704 is connected to the motor stator fixing seat 7033 and is used to measure the rotation angle of the motor hollow rotor 7031. The other end of the force sensor force-measuring body 7061 is fixed to the active clamp head, and the force sensor force-measuring body 7061 is connected to the corresponding loading crossbeam 701 through a needle roller bearing 707. The driven rotary tensile clamp includes a driven torque motor 712, a thrust ball bearing 711, and a driven clamp head 710 that are connected in sequence, and the thrust ball bearing 711 is connected to the corresponding loading crossbeam 701. The active rotary tensile clamp is connected to the corresponding loading crossbeam 701 through a needle roller bearing 707 and a thrust ball bearing. The driven rotary tensile clamp is connected to the corresponding loading crossbeam 701 through a thrust ball bearing 711. The needle roller bearing 707 can ensure that the active rotary tensile clamp has a definite position in the circumferential direction but can move along the axial direction. The thrust ball bearing 711 can restrict the axial movement of the active rotary tensile clamp and the driven rotary tensile clamp but can ensure their rotation along the circumferential direction. The two are used in combination to ensure that during the tensile loading process of the two sets of rotatable clamps, they can rotate along the circumferential direction without axial crosstalk, ensuring the coaxiality and axial position between the two sets of rotatable clamps.

[0056] This embodiment provides a mechanical property testing device for solid propellants that is compatible with SEM and CT. It includes an in-situ mechanical testing device 7 for mechanically loading and maintaining the load on the propellant specimen 709. After obtaining the surface morphology information of the propellant specimen 709 using the scanning electron microscope 4, the in-situ mechanical testing device 7 under load can be transferred to the vacuum transfer chamber 1 through the transfer channel 2 on the wall of the electron microscope chamber. Then, the robotic arm transports the vacuum transfer chamber 1 separated from the transfer channel 2 to the scanning turntable of the dual-source dual-detector industrial CT 5 according to a predetermined spatial movement trajectory. The two rotatable fixtures of the in-situ mechanical testing device 7 in the vacuum transfer chamber 1 rotate synchronously in the same direction (or synchronously in the opposite direction, asynchronously in the same direction, asynchronously in the opposite direction) with the scanning frequency of the radiation source in the dual-source dual-detector industrial CT 5 to obtain the internal three-dimensional structure information of the propellant specimen 709 during mechanical loading. After that, the in-situ mechanical testing device 7 can be transported to the transfer channel 2 again and finally transported to the electron microscope chamber of the scanning electron microscope 4 through the transfer channel 2. The in-situ mechanical testing device 7 continuously applies mechanical loading to the propellant specimen 709 and performs scanning electron microscope 4 imaging as needed. In this way, by continuously adjusting the working states between the in-situ mechanical testing device 7 and the microscopic imaging device, repeatable testing can be achieved, ensuring more comprehensive and accurate mesoscopic failure information of the propellant specimen 709 while incurring less time cost.

[0057] As Figure 9 shown, another embodiment of the present invention proposes a method for testing the mechanical properties of solid propellants that is compatible with SEM and CT. This testing method is implemented based on the testing device described in the foregoing embodiment and can enable SEM and CT to obtain the microscopic structure failure forms of the propellant specimen in the same state. Specifically, this testing method includes the following steps S1 - S9.

[0058] S1: The robotic arm 6 transports the vacuum transfer chamber 1 to the docking position of the transfer channel 2, opens the corresponding vacuum valves (the transfer chamber hatch 101 and the vacuum pneumatic flap valve 3), connects the vacuum transfer chamber 1 to the scanning electron microscope 4 through the transfer channel 2, and extracts the vacuum degrees of the scanning electron microscope 4, the transfer channel 2, and the vacuum transfer chamber 1 to a preset vacuum degree, for example, to 0.025 Pa - 0.055 Pa, and maintains the vacuum degree.

[0059] S2: Determine the loading form of the mechanical property test of the propellant specimen, and judge whether it is an in-situ tensile test. If it is an in-situ tensile test, set the active frameless torque motor 703 and the slave torque motor 712 to the master-slave following mode; if it is a tensile-torsion test, set the active frameless torque motor 703 and the slave torque motor 712 to run independently.

[0060] S3: Turn on the electron gun of the scanning electron microscope 4 and locate the test target area of the propellant specimen 709.

[0061] S4: Set the loading parameters for the mechanical property test of the in-situ mechanical test device 7 through the system control and data acquisition and processing unit, including parameters such as the tensile loading speed, the displacement of a single tensile, and the total tensile displacement. The in-situ mechanical test device 7 completes the loading of the target parameters and keeps the load without unloading. Among them, the system control and data acquisition and processing unit is used to control the operation of the motor in the entire solid propellant mechanical property test device, the movement of the in-situ mechanical test device 7 within the scanning electron microscope 4, its movement in the transfer channel 2, its movement in the vacuum transfer chamber 1, the adsorption and combination of the robotic arm 6 and the vacuum transfer chamber 1, the movement trajectory of the robotic arm 6, and the rotational movement of the scanning turntable 52, etc., and can collect the tensile force value, displacement information in the in-situ mechanical test device 7, and the state information of the movement conversion of the in-situ mechanical test device 7 between the scanning electron microscope 4 and the dual-source dual-detector industrial CT 5, etc.;

[0062] S5: Adjust the imaging angle of the propellant specimen 709. First, determine whether it is an SEM / EDS / DIC test. If so, the active frameless torque motor 703 and the slave torque motor 712 synchronously rotate the two sets of rotatable clamps in the same direction to the first deflection angle state, such as the 0° deflection angle state (as Figure 3 shown); if not, continue to determine whether it is an EBSD test. If it is an EBSD test, the active frameless torque motor 703 and the slave torque motor 712 adjust the two sets of rotatable clamps to the second deflection angle state, such as the 70° deflection angle state. After adjusting the imaging angle, use the scanning electron microscope 4 to obtain the microscopic morphology information of the surface of the target area. Among them, the deflection angle of the two sets of rotatable clamps refers to the angle between the upper surfaces of the active clamp head 708 and the driven clamp head 710 in the two sets of rotatable clamps and the upper surface of the loading crossbeam 701. When their upper surfaces are parallel, it is the 0° deflection angle state, and when the angle between the two planes is 70°, it is the 70° deflection angle state.

[0063] S6: Determine the content of obtaining the microstructural information. Judge whether the information obtained by the scanning electron microscope 4 is complete according to the test requirements and imaging effects and conduct a CT imaging test, that is, judge whether the mechanical property test in the scanning electron microscope 4 is completed. If it is completed, transfer the in-situ mechanical test device 7 to the vacuum transfer chamber 1 through the transfer channel 2, and use the moving platform inside the vacuum transfer chamber 1 to transport the propellant specimen 709 below the high-transparency scanning window 106. Then, close the transfer chamber door 101 and the vacuum pneumatic flap valve 3 in sequence. After evacuating the vacuum of the low-vacuum section transfer channel 202, the robotic arm 6 transports the vacuum transfer chamber 1 to the center of the scanning turntable 52 in the dual-source dual-detector industrial CT 5. If it is still necessary to further obtain the mechanical property test information of the propellant specimen 709, further load the propellant specimen 709 and return to step S4, and repeat steps S4 to S6 until the mechanical property test in the scanning electron microscope 4 ends;

[0064] S7: Synchronize the scanning frequency of the radiation source 53 in the dual-source dual-detector industrial CT 5 and the rotation speed of the two sets of jigs in the in-situ mechanical testing device 7. The X-rays emitted by the radiation source 53 penetrate the high-transparency scanning window 106 and the propellant sample 709 and then irradiate the CT detector 51 to obtain the internal three-dimensional structure information during the rotational scanning process of the propellant sample 709.

[0065] S8: After the dual-source dual-detector industrial CT 5 finishes scanning and imaging, determine whether the obtained mechanical test data is complete, that is, determine whether the mechanical property test in the dual-source dual-detector industrial CT 5 is completed. If it is completed, the robotic arm 6 docks the vacuum transfer chamber 1 with the transfer channel 2 on the scanning electron microscope 4, opens the transfer chamber door 101 and the vacuum pneumatic gate valve 3 to establish a vacuum channel between the vacuum transfer chamber 1, the transfer channel 2 and the scanning electron microscope 4, and transports the in-situ mechanical testing device 7 to the electron microscope chamber of the scanning electron microscope 4 through the transfer channel 2. If it is not completed, return to step S7.

[0066] S9: Determine the progress of the in-situ mechanical property test in the scanning electron microscope 4 and the dual-source dual-detector industrial CT 5, and judge whether the combined mechanical property test in the scanning electron microscope 4 and the dual-source dual-detector industrial CT 5 is completed. If it is completed, evacuate the vacuum of the scanning electron microscope 4 and replace the propellant sample 709. If it is necessary to continue obtaining the morphological information of the propellant sample 709, return to step S3 and repeat steps S3 to S9 until the combined mechanical property test is completed and complete test information is obtained, and then end.

[0067] The present invention provides a test device and a test method for the mechanical properties of a propellant that are synchronously compatible with a scanning electron microscope and a CT. During the mechanical loading and load holding process, the in-situ mechanical test device is wrapped in a vacuum rotary chamber. By utilizing the flexibility and convenience of the robotic arm, the in-situ mechanical test device can be quickly transferred between the scanning electron microscope and the dual-source dual-detector industrial CT. The sealed vacuum rotary chamber avoids the number of times and the time for the scanning electron microscope to repeatedly evacuate when the in-situ mechanical test device switches imaging devices. The two sets of rotatable clamps in the test device can adjust the imaging angle of the propellant specimen according to different imaging modes of the scanning electron microscope, and can also adjust the angle of the propellant specimen in real time following the scanning frequency of the radiation source in the dual-source dual-detector industrial CT. Through the test device and test method designed by the present invention, the optimal sampling time interval and the proportion of the number of times for image acquisition using the scanning electron microscope and the CT can be set. By utilizing the characteristic of fast imaging of the scanning electron microscope, a large amount of surface topography information of the specimen can be obtained. At the same time, by utilizing the characteristic that the CT scan can obtain the internal three-dimensional structure information of the specimen, only a small amount of the internal structure damage evolution form of the surface failure area can be accurately obtained. While completely obtaining the surface and internal failure forms of the propellant specimen, the influence of stress relaxation on the mechanical properties of the propellant specimen is effectively avoided, ensuring the accuracy of the material mechanical property test, and providing a newer and more effective technical means for scientifically establishing the relationship between the mesoscopic tissue evolution and the macroscopic mechanical property dynamic response of the propellant under complex load actions.

[0068] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0069] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A mechanical property testing device for solid propellants compatible with SEM and CT, characterized in that, Comprising: A scanning electron microscope (4) provided with a transfer channel (2) communicating with the electron microscope chamber of the scanning electron microscope (4) for obtaining surface topography information of a propellant sample (709); A dual-source dual-detector industrial CT (5) for obtaining internal three-dimensional structure information of the propellant sample (709); A vacuum transfer chamber (1) including a transfer chamber door (101), a transfer chamber main cavity (102), a transfer chamber scanning window bracket (105), and a high-transparency scanning window (106). Inside the transfer chamber main cavity (102), there is a moving platform for transporting an in-situ mechanical testing device (7). The high-transparency scanning window (106) is installed on the side wall of the transfer chamber main cavity (102) through the transfer chamber scanning window bracket (105). The transfer chamber door (101) is connected to the front end of the transfer chamber main cavity (102) for controlling the connection and isolation between the transfer chamber main cavity (102) and the transfer channel (2); A robotic arm (6) for transporting the vacuum transfer chamber (1) containing the in-situ mechanical testing device (7) between the docking position of the transfer channel (2) and the scanning turntable (52) of the dual-source dual-detector industrial CT (5) according to a predetermined spatial motion trajectory, and maintaining a high-vacuum environment during the transportation of the vacuum transfer chamber (1); The transfer channel (2) is provided with a vacuum pneumatic flap valve (3) for controlling the connection and isolation of the transfer channel (2) and is used for transmitting the in-situ mechanical testing device (7) between the transfer chamber main cavity (102) and the electron microscope chamber; The in-situ mechanical testing device (7) includes a bidirectional mechanical loading platform and two sets of rotatable clamps mounted on the bidirectional mechanical loading platform. Both ends of the propellant sample (709) are respectively fixed and clamped by the two rotatable clamps. The two sets of rotatable clamps perform stretching and / or rotating actions synchronously according to the scanning imaging rhythm of the scanning electron microscope and the dual-source dual-detector industrial CT, including synchronous co-rotating, synchronous counter-rotating, asynchronous co-rotating, and asynchronous counter-rotating, to perform mechanical loading and hold the load on the propellant sample (709).

2. The mechanical property testing device for solid propellants compatible with SEM and CT according to claim 1, wherein The bidirectional mechanical loading platform includes a bidirectional trapezoidal lead screw (702) and two loading crossbeams (701) threadedly engaged with the bidirectional trapezoidal lead screw (702); The two sets of rotatable clamps are respectively connected to the two loading crossbeams (701), and the bidirectional trapezoidal lead screw (702) drives the loading crossbeams (701) to drive the rotatable clamps thereon to perform stretching motion.

3. The mechanical property testing device for solid propellants compatible with SEM and CT according to claim 1 or 2, characterized in that, The two sets of rotatable fixtures are divided into an active rotatable tensile fixture and a driven rotatable tensile fixture. The active rotatable tensile fixture includes an active frameless torque motor (703), an encoder (704), a slip ring (705), a force sensor (706), a needle roller bearing (707), a thrust ball bearing, and an active fixture head (708). The active frameless torque motor (703) includes a motor hollow rotor (7031), a motor stator (7032), and a motor stator fixing seat (7033). The force sensor (706) includes a force sensor force-measuring body (7061) and a force sensor signal wire (7062). One end of the force sensor force-measuring body (7061) is connected to the motor hollow rotor (7031). The motor hollow rotor (7031) is connected to the corresponding loading crossbeam (701) through a thrust ball bearing. The force sensor signal wire (7062) passes through the motor hollow rotor (7031) and is connected to the slip ring (705) installed at the end of the encoder (704). The motor stator (7032) is installed on the motor stator fixing seat (7033). The encoder (704) is connected to the motor stator fixing seat (7033). The other end of the force sensor force-measuring body (7061) is fixed to the active fixture head (708), and the force sensor force-measuring body (7061) is connected to the corresponding loading crossbeam (701) through a needle roller bearing (707). The driven rotatable tensile fixture includes a driven torque motor (712), a thrust ball bearing (711), and a driven fixture head (710) connected in sequence, and the thrust ball bearing (711) is connected to the corresponding loading crossbeam (701).

4. The mechanical property testing device for solid propellants compatible with SEM and CT according to claim 1 or 2, characterized in that, The dual-source dual-detector industrial CT (5) includes a frame body and a CT detector (51), a scanning turntable (52), and a radiation source (53) arranged on the frame body. The CT detector (51) and the radiation source (53) are symmetrically arranged relative to the scanning turntable (52). When the vacuum rotary chamber (1) containing the in-situ mechanical testing device (7) is located on the scanning turntable (52), the moving platform in the main cavity (102) of the rotary chamber moves the propellant sample (709) clamped in the in-situ mechanical testing device (7) below the high-permeability scanning window (106), so that the X-rays emitted by the radiation source (53) penetrate the high-permeability scanning window (106) and the propellant sample (709) and irradiate the CT detector (51).

5. The mechanical property testing device for solid propellants compatible with SEM and CT according to claim 4, characterized in that, The radiation source (53) uses a micro-focus radiation source.

6. The solid propellant mechanical property testing device compatible with SEM and CT according to claim 1 or 2, characterized in that The vacuum pneumatic gate valve (3) divides the transfer channel (2) into a high-vacuum section transfer channel (201) and a low-vacuum section transfer channel (202). The high-vacuum section transfer channel (201) is directly connected to the electron microscope chamber, and the vacuum degree of the low-vacuum section transfer channel (202) is regulated by the vacuum pneumatic gate valve (3).

7. The mechanical property testing device for solid propellants compatible with SEM and CT according to claim 1 or 2, characterized in that, A suction cup is installed at the end of the robotic arm (6), and the suction cup is connected to the vacuum rotary chamber (1) using the principle of vacuum negative pressure.

8. A method for testing the mechanical properties of solid propellants compatible with SEM and CT, characterized in that, Including the following steps: S1: The robotic arm (6) transports the vacuum transfer chamber (1) to the docking position of the transfer channel (2), opens the transfer chamber hatch (101) and the vacuum pneumatic slide valve (3), connects the vacuum transfer chamber (1) with the scanning electron microscope (4), and pumps the vacuum degrees of the scanning electron microscope (4), the transfer channel (2) and the vacuum transfer chamber (1) to a preset vacuum degree and maintains it; S2: Determine the loading form of the mechanical property test of the propellant sample. If it is an in-situ tensile test, set the active frameless torque motor (703) and the slave torque motor (712) to the master-slave following mode; if it is a tensile-torsion test, control the active frameless torque motor (703) and the slave torque motor (712) to run independently; S3: Turn on the electron gun of the scanning electron microscope (4) and locate the test target area of the propellant sample (709); S4: Set the loading parameters of the mechanical property test. The in-situ mechanical test device (7) completes the loading of the target parameters and maintains the load without unloading; S5: Judge whether it is a SEM / EDS / DIC test. If so, the active frameless torque motor (703) and the slave torque motor (712) synchronously rotate the two sets of rotatable clamps to the first deflection angle state in the same direction; if not, continue to judge whether it is an EBSD test. If so, the active frameless torque motor (703) and the slave torque motor (712) adjust the two sets of rotatable clamps to the second deflection angle state. After adjusting the imaging angle, the scanning electron microscope (4) obtains the microscopic morphology information on the surface of the test target area; S6: Judge whether the mechanical property test in the scanning electron microscope (4) is completed. If so, transfer the in-situ mechanical test device (7) to the inside of the vacuum transfer chamber (1) through the transfer channel (2), and transport the propellant sample (709) to below the high-transparency scanning window (106) through the mobile platform inside the vacuum transfer chamber (1). Close the transfer chamber hatch (101) and the vacuum pneumatic slide valve (3) in sequence. After venting the vacuum of the low-vacuum section transfer channel (202), the robotic arm (6) transports the vacuum transfer chamber (1) to the scanning turntable (52) in the dual-source dual-detector industrial CT (5); S7: Synchronously control the scanning frequency of the radiation source (53) in the dual-source dual-detector industrial CT (5) and the rotation speed of the two sets of rotatable clamps in the in-situ mechanical test device (7). The X-rays emitted by the radiation source (53) penetrate the high-transparency scanning window (106) and the propellant sample (709) and then irradiate the CT detector (51) to obtain the internal three-dimensional structure information of the propellant sample (709) during the rotation scanning process; S8: After the scanning and imaging of the dual-source dual-detector industrial CT (5) is completed, it is judged whether the mechanical property test inside the dual-source dual-detector industrial CT (5) is finished. If so, the robotic arm (6) transports the vacuum transfer chamber (1) to dock with the transfer channel on the scanning electron microscope (4), opens the transfer chamber door (101) and the vacuum pneumatic gate valve (3), establishes a vacuum channel between the vacuum transfer chamber (1), the transfer channel (2) and the scanning electron microscope (4), and transports the in-situ mechanical test device (7) into the scanning electron microscope (4) through the transfer channel (2); S9: It is judged whether the combined mechanical property test between the scanning electron microscope (4) and the dual-source dual-detector industrial CT (5) is finished. If so, the vacuum of the scanning electron microscope (4) is relieved and the propellant sample (709) is replaced; if not, return to step S3 until the combined mechanical property test is completed.

9. The method for testing the mechanical properties of solid propellants compatible with SEM and CT according to claim 8, characterized in that, After step S6 and before step S7, the following steps are further included: If it is necessary to further obtain the mechanical property test information of the propellant sample (709), the propellant sample (709) is further loaded and then return to step S4 until the mechanical property test in the scanning electron microscope (4) is finished.

10. The method for testing the mechanical properties of solid propellants compatible with SEM and CT according to claim 8 or 9, characterized in that, The preset vacuum degree range is 0.025 Pa to 0.055 Pa, the first deflection angle state is the 0° deflection angle state, and the second deflection angle state is the 70° deflection angle state.

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