Axial vibration test device and method for solid propellant tensile specimen

Abstract

The present invention discloses an axial vibration test device and method for a solid propellant tensile specimen, the device comprising an axial vibration base, a pre-stressing regulator, a first axial vibration pressure plate and a second axial vibration pressure plate; a first groove is provided on the axial vibration base, one side and the top of the first groove are open, the first axial vibration pressure plate is connected to the axial vibration base and covers the side opening of the first groove; a second groove is provided on the pre-stressing regulator, one side and the bottom of the second groove are open, the pre-stressing regulator is connected to the axial vibration base, the second groove is located directly above the first groove, the second axial vibration pressure plate is detachably connected to the pre-stressing regulator and covers the side opening of the second groove. The present invention relates to the field of vibration testing, not only has a simple structure and is easy to use, but also can fill the gap in the axial vibration test device of the propellant vibration test, and can serve all aspects of the vibration test.

Description

Technical Field

[0001] The invention relates to the technical field of vibration testing, in particular to an axial vibration testing device and method for a solid propellant tensile specimen. Background Art

[0002] Solid propellants have the advantages of simple structure, low cost and high stability, and have been widely used. Among them, the structural integrity of solid motor grains directly affects the success rate of solid rocket ignition and launch, and is a key issue in the aerospace field.

[0003] During the transportation and storage of solid rocket engines, long-term vibration will cause damage to the grain, which will lead to a decrease in the mechanical properties of the propellant and seriously affect the structural integrity of the grain. Therefore, it is necessary to carry out vibration tests on solid propellants to study the damage evolution law and mechanical property degradation law of solid propellants under vibration loads, and provide a basis for the structural integrity analysis of the grain. Since the stress field of the propellant under axial vibration is relatively simple and closer to the stress distribution in actual engineering, it is easy to study the quantitative relationship between vibration load and propellant damage. It is urgent to carry out axial vibration tests on solid propellants to provide theoretical guidance for engineering practice.

[0004] At present, most axial vibration tests of solid propellants are carried out with the help of electronic universal testing machines or dynamic thermomechanical analyzers, etc., to apply periodic force or displacement loads to both ends of the dumbbell-shaped specimens, so that the stress field and strain field of the propellant show periodic changes, thereby simulating the vibration conditions during transportation and storage. In actual engineering, propellants are more subject to acceleration loads, and the stress and strain distribution are significantly different from those in axial tension and compression. The above loading mode cannot fully simulate the real load. In addition, the existing axial vibration test of solid propellants only provides vibration aging conditions for the test pieces, and cannot monitor and record the physical quantities during the vibration process, making it difficult to conduct theoretical analysis and verification of the axial vibration of solid propellants.

[0005] The existing axial vibration fixtures still have the following problems: 1) The two ends of the test section cannot be completely fixed, and the test piece cannot be guaranteed to reciprocate along the same axis during the vibration process, and the load transfer accuracy is low; 2) It is not convenient to adjust the fixture spacing, and it is impossible to apply a certain preload to eliminate the influence of the fixture gravity on the test piece, and there is a deviation between the test vibration conditions and the actual vibration load; 3) The surface of the test piece is blocked, and it is impossible to obtain the temperature change of the test piece during the vibration process, explore the vibration heating law, and quantitatively analyze the relationship between propellant damage and fatigue heating. To this end, it is necessary to design an axial vibration test device to accurately transfer the acceleration load to the test piece to simulate the forced vibration of solid propellant under actual working conditions. Summary of the invention

[0006] In view of the deficiencies in the above-mentioned prior art, the present invention provides an axial vibration test device and method for a solid propellant tensile specimen. Relying on the existing electric vibration test system, it is not only simple in structure and easy to use, but also can fill the gap in the axial vibration test device for propellant vibration experiments. It can serve all aspects of vibration experiments, can accurately transmit acceleration loads, apply axial vibration acceleration loads in actual engineering, apply pre-stress to eliminate the influence of fixtures, and provide an exposed test section for temperature monitoring.

[0007] To achieve the above-mentioned object, the present invention provides an axial vibration test device for a solid propellant tensile specimen, comprising an axial vibration base, a preload regulator, a first axial vibration pressure plate and a second axial vibration pressure plate, wherein the axial vibration base is provided with a connecting structure for fixing the axial vibration base on an electric vibration test bench;

[0008] The axial vibration base is provided with a first groove into which the first end of the solid propellant tensile specimen can be embedded, and one side and the top end of the first groove are open, and the first axial vibration pressure plate is detachably connected to the axial vibration base, and the first axial vibration pressure plate covers the side opening of the first groove;

[0009] The pre-stressing regulator is provided with a second groove into which the second end of the solid propellant tensile specimen can be embedded, and one side and the bottom end of the second groove are open. The pre-stressing regulator is detachably connected to the axial vibration base, and the second groove is located directly above the first groove. The second axial vibration pressure plate is detachably connected to the pre-stressing regulator, and the second axial vibration pressure plate covers the side opening of the second groove.

[0010] In one embodiment, the axial vibration base includes a bottom plate, a vertical plate and a top plate connected in sequence from bottom to top, and the connecting structure is arranged on the bottom plate;

[0011] A protrusion is provided on one side of the bottom of the vertical plate, the first groove is provided on the protrusion, and the first axial vibration pressure plate is detachably connected to the protrusion;

[0012] The pre-stressing regulator is detachably connected to the vertical plate and the top plate respectively, and the pre-stressing regulator is located directly above the protrusion.

[0013] In one embodiment, the top plate is provided with a first threaded hole, and the top of the preload regulator is provided with a second threaded hole;

[0014] The first threaded hole is coaxial with the second threaded hole, and the preload regulator is detachably connected to the top plate through the cooperation of the first threaded hole, the second threaded hole, and screws, so as to achieve height adjustment of the preload regulator;

[0015] The vertical plate is provided with a plurality of third threaded holes distributed in a rectangular array, and the side of the pre-force regulator is provided with first strip holes corresponding to the third threaded holes one by one, and the length direction of the first strip holes is parallel to the vertical direction. The pre-force regulator is detachably connected to the vertical plate through the cooperation of the third threaded holes, the corresponding first strip holes, and screws to achieve horizontal position adjustment of the pre-force regulator.

[0016] In one embodiment, the second axial vibration platen is provided with second strip holes corresponding to the third threaded holes one by one, and the length direction of the second strip holes is parallel to the vertical direction;

[0017] The second axial vibration pressure plate, the preload regulator and the vertical plate are detachably connected through the cooperation of the third threaded hole, the corresponding first strip hole, the corresponding second strip hole and screws.

[0018] In one embodiment, the axial vibration base is provided with a plurality of fourth threaded holes distributed in a rectangular array, the first axial vibration pressure plate is provided with third strip holes corresponding one-to-one to the fourth threaded holes, and the length direction of the third strip holes is parallel to the vertical direction;

[0019] The axial vibration base and the first axial vibration pressure plate are detachably connected through the cooperation of the fourth threaded hole, the corresponding third strip hole, and the screw.

[0020] In one embodiment, a first convex pad is provided on the side of the first axial vibration platen, and the first convex pad is embedded in the side opening of the first groove to abut against the side of the first end of the solid propellant tensile specimen;

[0021] A second convex pad is provided on the side of the second axial vibration pressure plate, and the second convex pad is embedded in the side opening of the second groove to abut against the side of the second end of the solid propellant tensile specimen.

[0022] In one embodiment, a first rubber pad is provided on the bottom groove wall of the first groove to fill the gap between the bottom groove wall of the first groove and the first end of the solid propellant tensile specimen;

[0023] A second rubber pad is provided on the top groove wall of the second groove to fill the gap between the bottom top groove wall of the second groove and the second end of the solid propellant tensile specimen.

[0024] In one embodiment, the connection structure is a fifth threaded hole provided at the bottom of the axial vibration base.

[0025] To achieve the above object, the present invention also provides an axial vibration test method for a solid propellant tensile specimen, and uses the above axial vibration test device to perform an axial vibration test on the solid propellant tensile specimen.

[0026] In one embodiment, the method specifically comprises the following steps:

[0027] The solid propellant tensile specimens are numbered, and the original microscopic structural images of the surface of the test section of each solid propellant tensile specimen are taken and stored using a scanning electron microscope. The surface measuring points of the solid propellant tensile specimens are cleaned, and the strain gauges are attached to the surface measuring points of the solid propellant tensile specimens and the wires are welded. Then, the axial vibration test device is assembled and the solid propellant tensile specimens are placed.

[0028] The axial vibration test device with the solid propellant tensile specimen placed thereon is fixed to the vibration platform of the electrodynamic vibration test system, and an infrared imager is fixed around the electrodynamic vibration test system so that the infrared imager lens faces the temperature monitoring surface of the solid propellant tensile specimen to capture the temperature field data of the surface of the solid propellant tensile specimen, and then the strain gauge wire is connected to the strain gauge to record and store the strain field data of the solid propellant tensile specimen in real time during the vibration process;

[0029] According to the vibration data collected in the actual working conditions, select the waveform, frequency, acceleration amplitude or power spectrum density of the test loading, set the vibration time, and start the test after checking that everything is correct. Make the vibration platform reciprocate in the vertical direction under the set acceleration conditions. The reciprocating motion is transmitted to the solid propellant tensile specimen by the axial vibration test device to realize the loading of the vibration acceleration load.

[0030] Record the surface temperature distribution cloud diagram of the solid propellant tensile specimen at different times during the vibration process, record the curve of the maximum surface temperature of the solid propellant tensile specimen changing with time during the vibration process, and record the curve of the strain changing with time at each surface measuring point on the solid propellant tensile specimen;

[0031] The intrinsic relationship between temperature rise and structural damage is analyzed based on the surface temperature distribution cloud map of the solid propellant tensile specimen; the surface maximum temperature variation curve of the solid propellant tensile specimen with time is combined with the strain variation curve with time to analyze the mechanism of temperature rise; the surface maximum temperature of the solid propellant tensile specimen at different times and the strain of each surface measuring point are compared with the theoretical model to verify the accuracy of the model;

[0032] Select at least one solid propellant tensile specimen from a group of solid propellant tensile specimens after vibration, slice the test section, and use a scanning electron microscope to take a microscopic structural image of the surface of the test section after vibration, compare the microscopic structural image after vibration with the original microscopic structural image, and analyze the influence of vibration loads in actual engineering on the propellant microstructure;

[0033] Prepare several unvibrated solid propellant tensile specimens and vibrated solid propellant tensile specimens, measure and record the size of the test section of each solid propellant tensile specimen, stretch the unvibrated solid propellant tensile specimens and the vibrated solid propellant tensile specimens at a stretching rate of 1-3 mm / min until they break, record the force-displacement curve during stretching, calculate the initial modulus, tensile strength, breaking strength, maximum elongation and elongation at break of each solid propellant tensile specimen, compare the initial modulus, tensile strength, breaking strength, maximum elongation and elongation at break of the unvibrated solid propellant tensile specimens and the vibrated solid propellant tensile specimens, and obtain the degradation law of the mechanical properties of the propellant under vibration conditions;

[0034] The fracture surface of the solid propellant tensile specimen was sliced, and the microstructure image of the fracture surface was taken using a scanning electron microscope. The microstructure image of the fracture surface of the solid propellant tensile specimen after vibration was compared with that of the fracture surface without vibration, and the effect of vibration aging on the propellant failure mode was analyzed.

[0035] Compared with the prior art, the present invention has the following beneficial technical effects:

[0036] 1. The axial vibration test method for the solid propellant tensile specimen of the present invention can apply a vibration acceleration load to the solid propellant tensile specimen through the reciprocating motion of the vibration table plane with the help of the existing electric vibration test system to simulate the actual working conditions;

[0037] 2. The solid propellant tensile specimen axial vibration test method of the invention can monitor the temperature field and strain field of the solid propellant tensile specimen in real time during the vibration process and store the test data with the help of an infrared imager, a strain measurement system, an electron microscope scanning system, an electronic universal testing machine and related software configurations, and can be used for theoretical analysis of the axial vibration of solid propellants;

[0038] 3. The solid propellant tensile specimen axial vibration test device of the present invention comprises an axial vibration pressure plate, and a baffle is provided on the inner side of the preload regulator for fixing the solid propellant tensile specimen; when installing the solid propellant tensile specimen, rubber pads are placed in the gaps at both ends of the solid propellant tensile specimen to fix the solid propellant tensile specimen, ensuring that there is no relative displacement between the solid propellant tensile specimen and the test device during the vibration process, thereby greatly improving the accuracy of vibration transmission and reducing the vibration test error;

[0039] 4. The preload regulator in the present invention is connected to the axial vibration base with screws, and the height of the preload regulator can be quickly adjusted by adjusting the position of the nut, ensuring that the solid propellant tensile specimen is in a stress-free state before the test begins, eliminating the interference of the fixture gravity during the test, and reducing the experimental error caused by the vibration test device;

[0040] 5. The solid propellant tensile specimen axial vibration test device of the present invention only fixes the two ends of the tensile solid propellant tensile specimen, and the overall structure does not block the test section of the solid propellant tensile specimen. An infrared imaging thermometer can be used to monitor the surface temperature of the test section in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 the structures shown in these drawings without paying creative work.

[0042] Figure 1 It is an axonometric diagram of an axial vibration test device (including a solid propellant tensile specimen) in an embodiment of the present invention;

[0043] Figure 2 It is a front view of an axial vibration test device (including a solid propellant tensile specimen) in an embodiment of the present invention;

[0044] Figure 3 It is a side view of an axial vibration test device (including a solid propellant tensile specimen) in an embodiment of the present invention;

[0045] Figure 4 is an axonometric view of an axial vibration base in an embodiment of the present invention;

[0046] Figure 5 It is a front view of the axial vibration base in the embodiment of the present invention;

[0047] Figure 6 It is an axonometric diagram of a preload regulator in an embodiment of the present invention;

[0048] Figure 7 is an axonometric view of a first axial vibration platen in an embodiment of the present invention;

[0049] Figure 8 is an axonometric view of a second axial vibration platen in an embodiment of the present invention;

[0050] Fig. 9 It is an axonometric diagram showing the installation of a solid propellant tensile specimen when the first axial vibration platen is not included in the embodiment of the present invention and the first axial vibration platen;

[0051] Fig.10 It is a front view showing the installation of a solid propellant tensile specimen when the first axial vibration pressure plate is not included in the embodiment of the present invention and when the first axial vibration pressure plate is not included.

[0052] Figure Number:

[0053] Axial vibration base 1, bottom plate 101, vertical plate 102, top plate 103, fifth threaded hole 104, first groove 105, protrusion 106, fourth threaded hole 107, first threaded hole 108, third threaded hole 109;

[0054] Preload regulator 2, second groove 201, second threaded hole 202, first strip hole 203;

[0055] A first axial vibration plate 3, a third strip hole 301, and a first convex pad 302;

[0056] A second axial vibration platen 4, a second strip hole 401, and a second convex pad 402;

[0057] Solid propellant tensile specimen5.

[0058] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0060] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0061] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0062] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0064] Example 1

[0065] like Figures 1 to 10 The figure shows an axial vibration test device for a solid propellant tensile specimen disclosed in this embodiment, which mainly includes an axial vibration base 1, a preload regulator 2, a first axial vibration pressure plate 3 and a second axial vibration pressure plate 4.

[0066] The axial vibration base 1 includes a bottom plate 101, a vertical plate 102 and a top plate 103 which are connected in sequence from bottom to top. The bottom plate 101, the vertical plate 102 and the top plate 103 are fixedly connected by welding, snap connection, angle plate connection or integral molding. The bottom plate 101 is parallel to the top plate 103, and the vertical plate 102 is arranged vertically and perpendicular to the bottom plate 101 and the top plate 103. A fifth threaded hole 104 is provided on the bottom plate 101 as a connection structure for fixing the axial vibration base 1 on the electric vibration test system. Specifically, the number of the fifth threaded holes 104 is multiple, and they are symmetrically distributed on both sides of the vertical plate 102.

[0067] The axial vibration base 1 is provided with a first groove 105 into which the first end of the solid propellant tensile specimen 5 can be embedded, and one side and the top end of the first groove 105 are open. The first axial vibration pressure plate 3 is detachably connected to the axial vibration base 1, and the first axial vibration pressure plate 3 covers the side opening of the first groove 105.

[0068] Specifically, a protrusion 106 is provided on one side of the bottom of the vertical plate 102, a first groove 105 is opened on the protrusion 106, a plurality of fourth threaded holes 107 distributed in a rectangular array are provided on the protrusion 106, a third strip hole 301 corresponding to the fourth threaded hole 107 is provided on the first axial vibration platen 3, and the length direction of the third strip hole 301 is parallel to the vertical direction, and the axial vibration base 1 and the first axial vibration platen 3 are detachably connected through the fourth threaded hole 107, the corresponding third strip hole 301, and the screw. Preferably, a first convex pad 302 is provided on the side of the first axial vibration platen 3, and the first convex pad 302 is embedded in the side opening of the first groove 105, and then abuts the side of the first end of the solid propellant tensile specimen 5, to ensure the fixation of both sides of the solid propellant tensile specimen 5. Among them, the third strip hole 301 is set as a vertical strip hole, so that when the protrusion 106 is connected to the first axial vibration pressure plate 3, the horizontal position of the first axial vibration pressure plate 3 can be adjusted, so that the first convex pad 302 on the first axial vibration pressure plate 3 can completely cover the side of the first end of the solid propellant tensile specimen 5, thereby fixing the relative position of the solid propellant tensile specimen 5 and the test device to transmit the acceleration load.

[0069] The pre-stress regulator 2 is provided with a second groove 201 into which the second end of the solid propellant tensile specimen 5 can be embedded, and one side and the bottom end of the second groove 201 are open. The pre-stress regulator 2 is detachably connected to the axial vibration base 1, and the second groove 201 is located directly above the first groove 105. The second axial vibration pressure plate 4 is detachably connected to the pre-stress regulator 2, and the second axial vibration pressure plate 4 covers the side opening of the second groove 201.

[0070] Specifically, a first threaded hole 108 is provided on the top plate 103, and a second threaded hole 202 is provided on the top of the pre-stressing regulator 2. The first threaded hole 108 is coaxial with the second threaded hole 202. The pre-stressing regulator 2 is detachably connected to the top plate 103 through the cooperation of the first threaded hole 108, the second threaded hole 202, and screws. The height of the pre-stressing regulator 2 can be adjusted by adjusting the depth of the threaded connection, thereby ensuring that the solid propellant tensile specimen 5 is in a stress-free state before the test begins, eliminating the interference of the fixture's gravity during the test, and reducing the experimental error caused by the vibration test device.

[0071] More specifically, the vertical plate 102 is provided with a plurality of third threaded holes 109 distributed in a rectangular array, the side of the pre-stressing regulator 2 is provided with a first strip hole 203 corresponding to the third threaded hole 109, and the second axial vibration platen 4 is provided with a second strip hole 401 corresponding to the third threaded hole 109. The length direction of the first strip hole 203 and the second strip hole 401 is parallel to the vertical direction. The pre-stressing regulator 2 is detachably connected to the vertical plate 102 through the third threaded hole 109, the corresponding first strip hole 203, and the screw, so as to achieve the horizontal position adjustment of the pre-stressing regulator 2. The second axial vibration platen 4, the pre-stressing regulator 2 and the vertical plate 102 are detachably connected through the third threaded hole 109, the corresponding first strip hole 203, the corresponding second strip hole 401, and the screw. By setting the first strip hole 203 as a strip hole along the vertical direction, it is convenient to locate the horizontal position of the pre-stressing regulator 2 when connecting the pre-stressing regulator 2 and the vertical plate 102, so that the second groove 201 of the pre-stressing regulator is aligned with the first groove 105, and eccentric loading during vibration is prevented, which causes experimental errors. Preferably, a second convex pad 402 is provided on the side of the second axial vibration platen 4, and the second convex pad 402 is embedded in the side opening of the second groove 201, and then abuts the side of the second end of the solid propellant tensile specimen 5 to ensure the fixation of both sides of the solid propellant tensile specimen 5. Among them, the second strip hole 401 is set as a strip hole along the vertical direction, and then the horizontal position of the second axial vibration platen 4 can be adjusted when the pre-stressing regulator 2 and the second axial vibration platen 4 are connected, so that the second convex pad 402 on the second axial vibration platen 4 can completely cover the side of the second end of the solid propellant tensile specimen 5, and then fix the relative position of the solid propellant tensile specimen 5 and the test device to transmit the acceleration load.

[0072] Before carrying out the axial vibration test of the solid propellant tensile specimen 5, the axial vibration test device is fixed through the fifth threaded hole 104 at the bottom of the axial vibration base 1, and the two ends of the solid propellant tensile specimen 5 are placed in the first groove 105 and the second groove 201 of the axial vibration base 1 and the preload regulator 2, and then the first axial vibration pressure plate 3 and the second axial vibration pressure plate 4 are respectively installed to fix the solid propellant tensile specimen 5 on the axial vibration test device. When the solid propellant tensile specimen 5 is placed, there may be gaps between the two ends of the solid propellant tensile specimen 5 and the groove walls of the first groove 105 and the second groove 201, so that the solid propellant tensile specimen 5 and the axial vibration test device produce relative slip during vibration, and the two ends of the solid propellant tensile specimen 5 will be subjected to additional supporting force. Therefore, in this embodiment, a first rubber pad is provided on the bottom groove wall of the first groove 105 to fill the gap between the bottom groove wall of the first groove 105 and the first end of the solid propellant tensile specimen 5. At the same time, a second rubber pad is provided on the top groove wall of the second groove 201 to fill the gap between the bottom and top groove walls of the second groove 201 and the second end of the solid propellant tensile specimen 5. The rubber pad is used to fill the gap so that the solid propellant tensile specimen 5 has no relative displacement with the test device during the vibration process, ensuring that the solid propellant tensile specimen 5 reciprocates along the same axis, reducing the vibration test error. After the solid propellant tensile specimen 5 is installed, the height of the preload regulator 2 is adjusted, and the test section is placed in a stress-free state in combination with the force sensor, eliminating the influence of the external force applied by the device, and then the vibration test can be carried out.

[0073] During the vibration test, since the solid propellant tensile specimen 5 is only covered and fixed at both ends and the middle portion is exposed, an infrared thermal imager can be used to monitor the surface temperature of the test section of the solid propellant tensile specimen 5.

[0074] Example 2

[0075] This embodiment discloses a method for an axial vibration test of a solid propellant tensile specimen, and an axial vibration test is performed on the solid propellant tensile specimen by using the axial vibration test device of Embodiment 1.

[0076] The method specifically comprises the following steps:

[0077] 1. Preparation before the test

[0078] 1) Label the solid propellant tensile specimen to be tested, use a scanning electron microscope to take the original microstructure image of the test section surface and store it;

[0079] 2) Clean the measuring point on the surface of the solid propellant tensile specimen and locate it with a marker pen, attach the strain gauge to the measuring point on the surface of the solid propellant tensile specimen and weld the wire to provide conditions for strain field measurement during the test.

[0080] 3) Device assembly: Assemble the axial vibration test device in Example 1 and place the solid propellant tensile specimen.

[0081] 4) Construction of vibration test platform: adjust the vibration platform of the electric vibration test system to an appropriate height; fix the axial vibration test device with the solid propellant tensile specimen on the vibration platform of the electric vibration test system. When the test starts, the vibration platform will reciprocate in the vertical direction at the set acceleration condition. The reciprocating motion is transmitted from the axial vibration test device to the solid propellant tensile specimen to realize the loading of vibration acceleration load; place a tripod around the electric vibration test system and fix the infrared imager. The infrared imager lens faces the temperature monitoring surface. Connect the power cord and network cable of the infrared imager to capture the surface temperature field data of the solid propellant tensile specimen and transmit and store the image data in real time; connect the strain gauge wire to the strain gauge to record and store the strain field data during the vibration process in real time.

[0082] 2. Vibration table test

[0083] 1) Test condition setting: According to the vibration data collected in the actual working conditions, select the waveform, frequency, acceleration amplitude or power spectrum density of the test load, select the vibration monitoring and control channel, and set the vibration time;

[0084] 2) Start the test: turn on the power amplifier in the electric vibration test system, check the test conditions to ensure that the test conditions are set correctly, check the test platform wiring to ensure that all physical quantities can be detected and recorded in real time, and then start the test;

[0085] 3) Data processing: record the surface temperature cloud map of the solid propellant tensile specimen at different times during the vibration process, record the curve of the maximum temperature of the solid propellant tensile specimen surface changing with time during the vibration process, and record the curve of the strain changing with time at each point;

[0086] 4) Result analysis: Analyze the intrinsic relationship between temperature rise and structural damage based on the surface temperature distribution cloud map of the solid propellant tensile specimen; combine the temperature change curve with the strain change curve to analyze the mechanism of temperature rise; compare the maximum surface temperature and strain of each point of the solid propellant tensile specimen at different times with the theoretical model to verify the accuracy of the model.

[0087] 3. Scanning electron microscope

[0088] 1) Solid propellant tensile specimen processing: Select 1-2 solid propellant tensile specimens from a group of solid propellant tensile specimens after vibration, and slice the test section;

[0089] 2) Start the test: Use a scanning electron microscope to photograph the microstructure of the test section surface after vibration and store the image;

[0090] 3) Result analysis: Compare the surface microstructure of the solid propellant tensile specimen after vibration with the microstructure before vibration, and analyze the influence of vibration load on the propellant microstructure in actual engineering.

[0091] 4. Uniaxial constant speed tensile test

[0092] 1) Dimension measurement: prepare several solid propellant tensile specimens without vibration and several solid propellant tensile specimens after vibration, and measure and record the dimensions of the test section of each solid propellant tensile specimen;

[0093] 2) Start the test: Stretch the unvibrated solid propellant tensile specimen and the vibrated solid propellant tensile specimen until they break at a stretching rate of 2 mm / min, and record the force-displacement curve during stretching;

[0094] 3) Data processing: Calculate the initial modulus, tensile strength, breaking strength, maximum elongation and elongation at break of each solid propellant tensile specimen;

[0095] 4) Result analysis: Compare the initial modulus, tensile strength, breaking strength, maximum elongation and breaking elongation of the solid propellant tensile specimens without vibration and the solid propellant tensile specimens after vibration to obtain the degradation law of the mechanical properties of the propellant under vibration conditions.

[0096] 5. Scanning electron microscope

[0097] 1) Solid propellant tensile specimen processing: Slice the fracture surface of the solid propellant tensile specimen after being pulled apart;

[0098] 2) Start the experiment: Use a scanning electron microscope to photograph the microstructure of the fracture surface and store the image;

[0099] 3) Result analysis: Compare the fracture microstructure of the solid propellant tensile specimen after vibration with that of the non-vibrated specimen to analyze the effect of vibration aging on the propellant failure mode.

[0100] In this embodiment, with the help of the existing electric vibration test system, a vibration acceleration load is applied to the solid propellant tensile specimen through the reciprocating motion of the vibration table plane. This is different from applying force and displacement loads in the axial tension and compression at both ends of the solid propellant tensile specimen, and can achieve simulation of actual working conditions.

[0101] During the test, the temperature field and strain field of the solid propellant tensile specimen during the vibration process can be monitored in real time through infrared imagers, strain measurement systems, scanning electron microscopes, electronic universal testing machines and related software, and the test data can be stored. This can be used for theoretical analysis and verification of the acceleration vibration of solid propellants, filling the gap in solid propellant axial vibration test equipment and test methods.

[0102] According to the test process in this embodiment, the temperature rise phenomenon and deformation trend during the vibration of the propellant can be analyzed and theoretically verified, and the microstructural changes, mechanical property degradation and failure mode changes caused by vibration can also be experimentally observed, forming a complete solid propellant axial vibration test and analysis system.

[0103] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A solid propellant tensile specimen axial vibration test device, characterized in that: It includes an axial vibration base, a preload regulator, a first axial vibration platen and a second axial vibration platen, wherein the axial vibration base is provided with a connecting structure for fixing the axial vibration base on an electric vibration test bench; The axial vibration base is provided with a first groove into which the first end of the solid propellant tensile specimen can be embedded, and one side and the top end of the first groove are open, and the first axial vibration pressure plate is detachably connected to the axial vibration base, and the first axial vibration pressure plate covers the side opening of the first groove; The pre-stressing regulator is provided with a second groove capable of being embedded in the second end of the solid propellant tensile specimen, and one side and the bottom end of the second groove are open, the pre-stressing regulator is detachably connected to the axial vibration base, and the second groove is located directly above the first groove, and the second axial vibration pressure plate is detachably connected to the pre-stressing regulator, and the second axial vibration pressure plate covers the side opening of the second groove; The axial vibration base comprises a bottom plate, a vertical plate and a top plate which are connected in sequence from bottom to top, and the connection structure is arranged on the bottom plate; a protrusion is arranged on one side of the bottom of the vertical plate, the first groove is arranged on the protrusion, and the first axial vibration pressure plate is detachably connected to the protrusion; the pre-force regulator is detachably connected to the vertical plate and the top plate respectively, and the pre-force regulator is located directly above the protrusion; The top plate is provided with a first threaded hole, and the top of the pre-stressing regulator is provided with a second threaded hole; the first threaded hole is coaxial with the second threaded hole, and the pre-stressing regulator is detachably connected to the top plate through the cooperation of the first threaded hole, the second threaded hole and a screw, so as to achieve height adjustment of the pre-stressing regulator; By adjusting the height of the preload regulator, the solid propellant tensile specimen is ensured to be in a stress-free state before the test begins, eliminating the interference of the fixture gravity during the test and reducing the experimental error caused by the vibration test device; The vertical plate is provided with a plurality of third threaded holes distributed in a rectangular array, and the side of the pre-force regulator is provided with first strip holes corresponding to the third threaded holes one by one, and the length direction of the first strip holes is parallel to the vertical direction. The pre-force regulator is detachably connected to the vertical plate through the third threaded holes, the corresponding first strip holes and screws to achieve horizontal position adjustment of the pre-force regulator.

2. The solid propellant tensile specimen axial vibration test device according to claim 1, characterized in that: The second axial vibration platen is provided with second strip holes corresponding to the third threaded holes one by one, and the length direction of the second strip holes is parallel to the vertical direction; The second axial vibration pressure plate, the preload regulator and the vertical plate are detachably connected through the cooperation of the third threaded hole, the corresponding first strip hole, the corresponding second strip hole and screws.

3. The solid propellant tensile specimen axial vibration test device according to claim 1 or 2, characterized in that: The axial vibration base is provided with a plurality of fourth threaded holes distributed in a rectangular array, the first axial vibration pressing plate is provided with third strip holes corresponding to the fourth threaded holes one by one, and the length direction of the third strip holes is parallel to the vertical direction; The axial vibration base and the first axial vibration pressure plate are detachably connected through the cooperation of the fourth threaded hole, the corresponding third strip hole and the screw.

4. The solid propellant tensile specimen axial vibration test device according to claim 1 or 2, characterized in that: A first convex pad is provided on the side of the first axial vibration platen, and the first convex pad is embedded in the side opening of the first groove to abut against the side of the first end of the solid propellant tensile specimen; A second convex pad is provided on the side of the second axial vibration pressure plate, and the second convex pad is embedded in the side opening of the second groove to abut against the side of the second end of the solid propellant tensile specimen.

5. The solid propellant tensile specimen axial vibration test device according to claim 1 or 2, characterized in that: A first rubber pad is provided on the bottom groove wall of the first groove to fill the gap between the bottom groove wall of the first groove and the first end of the solid propellant tensile specimen; A second rubber pad is provided on the top groove wall of the second groove to fill the gap between the top groove wall of the second groove and the second end of the solid propellant tensile specimen.

6. The solid propellant tensile specimen axial vibration test device according to claim 1 or 2, characterized in that: The connection structure is a fifth threaded hole arranged at the bottom of the axial vibration base.

7. A method for testing axial vibration of a solid propellant tensile specimen, characterized in that: An axial vibration test device according to any one of claims 1 to 6 is used to perform an axial vibration test on a solid propellant tensile specimen; The method specifically comprises the following steps: The solid propellant tensile specimens are numbered, and the original microscopic structural images of the surface of the test section of each solid propellant tensile specimen are taken and stored using a scanning electron microscope, and then the surface measuring point positions of the solid propellant tensile specimens are cleaned, and the strain gauges are attached to the surface measuring points of the solid propellant tensile specimens and welded with wires, and then the axial vibration test device described in any one of claims 1 to 6 is assembled and the solid propellant tensile specimens are placed. After the solid propellant tensile specimens are installed, the height of the preload regulator is adjusted, and the force sensor is combined to make the test section in a stress-free state, so as to eliminate the interference of the fixture gravity during the test process and reduce the experimental error caused by the vibration test device; The axial vibration test device with the solid propellant tensile specimen placed thereon is fixed to the vibration platform of the electrodynamic vibration test system, and an infrared imager is fixed around the electrodynamic vibration test system so that the infrared imager lens faces the temperature monitoring surface of the solid propellant tensile specimen to capture the temperature field data of the surface of the solid propellant tensile specimen, and then the strain gauge wire is connected to the strain gauge to record and store the strain field data of the solid propellant tensile specimen in real time during the vibration process; According to the vibration data collected in the actual working conditions, select the waveform, frequency, acceleration amplitude or power spectrum density of the test loading, set the vibration time, and start the test after checking that everything is correct. Make the vibration platform reciprocate in the vertical direction under the set acceleration conditions. The reciprocating motion is transmitted to the solid propellant tensile specimen by the axial vibration test device to realize the loading of the vibration acceleration load. Record the surface temperature distribution cloud diagram of the solid propellant tensile specimen at different times during the vibration process, record the curve of the maximum surface temperature of the solid propellant tensile specimen changing with time during the vibration process, and record the curve of the strain changing with time at each surface measuring point on the solid propellant tensile specimen; The intrinsic relationship between temperature rise and structural damage is analyzed based on the surface temperature distribution cloud diagram of solid propellant tensile specimens; The maximum surface temperature of the solid propellant tensile specimen is combined with the strain-time curve to analyze the mechanism of temperature rise. The maximum surface temperature of the solid propellant tensile specimen at different times and the strain of each surface measurement point are compared with the theoretical model to verify the accuracy of the model. Select at least one solid propellant tensile specimen from a group of solid propellant tensile specimens after vibration, slice the test section, and use a scanning electron microscope to take a microscopic structural image of the surface of the test section after vibration, compare the microscopic structural image after vibration with the original microscopic structural image, and analyze the influence of vibration loads in actual engineering on the propellant microstructure; Prepare several unvibrated solid propellant tensile specimens and vibrated solid propellant tensile specimens, measure and record the size of the test section of each solid propellant tensile specimen, stretch the unvibrated solid propellant tensile specimens and the vibrated solid propellant tensile specimens at a stretching rate of 1-3 mm / min until they break, record the force-displacement curve during stretching, calculate the initial modulus, tensile strength, breaking strength, maximum elongation and elongation at break of each solid propellant tensile specimen, compare the initial modulus, tensile strength, breaking strength, maximum elongation and elongation at break of the unvibrated solid propellant tensile specimens and the vibrated solid propellant tensile specimens, and obtain the degradation law of the mechanical properties of the propellant under vibration conditions; The fracture surface of the solid propellant tensile specimen was sliced, and the microstructure image of the fracture surface was taken using a scanning electron microscope. The microstructure image of the fracture surface of the solid propellant tensile specimen after vibration was compared with that of the fracture surface without vibration, and the effect of vibration aging on the propellant failure mode was analyzed.

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