Ultrahigh-temperature multi-axial-force thermal coupling test system and method for multi-layer thermal protection structure

Abstract

The invention discloses an ultrahigh-temperature multi-axial-force thermal coupling test system and method for a multi-layer thermal protection structure, and belongs to the field of multi-layer thermal protection structure testing. The system comprises an in-plane loading module, an out-of-plane loading module and an ultra-high-temperature radiation loading module which are loaded on a test piece, the in-plane loading module is connected with the periphery of the test piece through an in-plane extension type clamp so as to simulate an in-plane fatigue load; the out-of-plane loading module is connected with the end face of the test piece through an out-of-plane extension type tool so as to simulate an out-of-plane fatigue load; and the ultrahigh-temperature radiation loading module is attached to the end surface of the test piece, so that high-temperature loading can be provided, and meanwhile, the constancy of the loading temperature can be ensured. The problems that true values of ultrahigh-temperature loads and complex stress borne by the multi-layer thermal protection structure are difficult to obtain, the actual reference value is low and the like due to the fact that an existing test method cannot give consideration to tests of in-plane loads, out-of-plane loads and high-temperature loads at the same time are solved.

Description

Technical Field

[0001] The present invention belongs to the field of multi-layer thermal protection structure testing, and in particular relates to an ultra-high temperature multi-axial force-thermal coupling test system and method for a multi-layer thermal protection structure. Background Art

[0002] Hypersonic aircraft have the characteristics of high speed, strong penetration capability, good concealment, and short reaction time. They have become the core technology pursued by the aviation industry and an important direction for the development of the aviation industry at present and in the future. Compared with subsonic and supersonic aircraft, hypersonic aircraft face more severe aerodynamic heating challenges during flight. Due to the high temperature generated by aerodynamic heating, the shape of the aircraft is susceptible to ablation, and its internal equipment may not work properly. In order to avoid these adverse consequences, effective thermal protection structures must be adopted.

[0003] It is worth noting that aviation structures are often in a multi-axial stress state during use, which places higher requirements on the safety and reliability of thermal protection structures. At the same time, a single type of thermal protection material and structure is difficult to meet the corresponding load-bearing and heat-insulating requirements, and multi-layer integrated thermal protection structures have emerged. Therefore, multi-axial force-thermal coupling experimental research on hypersonic aircraft thermal protection structures in ultra-high temperature environments is particularly important and has great significance for promoting the development of hypersonic aircraft technology.

[0004] In order to fully verify the performance of multi-layer thermal protection structures in ultra-high temperature and multi-axial thermal coupling environments, it is necessary not only to simulate the actual thermal load environment, but also to simultaneously apply multi-axial static and fatigue loads during the test. At present, the published thermal coupling test method for multi-layer thermal protection structures of C / SiC materials provides a thermal load environment through an electrically heated ceramic resistor plate, which has disadvantages such as a slow heating rate; and can only apply out-of-plane static loads, not multi-axial fatigue loads. The published thermal coupling virtual test method uses quartz lamp heating, and the operating temperature cannot exceed 1000 degrees Celsius; the size of the quartz lamp limits the device from being used for small test pieces, etc.

[0005] In summary, the existing technology cannot well simulate the ultra-high temperature loads and complex stresses that the multi-layer thermal protection structure of a hypersonic aircraft bears under actual working conditions. Therefore, in response to the needs of ultra-high temperature multi-axial force thermal coupling tests on multi-layer thermal protection structures, the present invention establishes a principle test method for ultra-high temperature multi-axial force thermal coupling response characteristics of multi-layer thermal protection structures suitable for small test pieces. Summary of the invention

[0006] Technical issues to be solved:

[0007] In order to avoid the shortcomings of the prior art, the present invention provides an ultra-high temperature multi-axial force-thermal coupling test system and method for a multi-layer thermal protection structure, which integrates in-plane loads, out-of-plane loads, and high-temperature loads (above 1200 degrees Celsius), and combined with special tooling, can achieve precise loading of the testing machine, thereby solving the problem that the existing test method cannot take into account the simultaneous loading of in-plane loads, out-of-plane loads, and high-temperature loads, resulting in difficulty in obtaining the true values ​​of the ultra-high temperature loads and complex stresses borne by the multi-layer thermal protection structure, and the actual reference value is low.

[0008] The technical solution of the present invention is: a multi-layer thermal protection structure ultra-high temperature multi-axial force-thermal coupling test system, comprising an in-plane loading module, an out-of-plane loading module and an ultra-high temperature radiation loading module loaded on a test piece;

[0009] The in-plane loading module is connected to the periphery of the test piece through an in-plane extension fixture, and the multi-axial loading force applied by the in-plane loading module is transmitted to the test piece along a set direction through the in-plane extension fixture to simulate the in-plane fatigue load;

[0010] The out-of-plane loading module is connected to the end face of the test piece through an out-of-plane extension tooling, and the loading force of the out-of-plane loading module is vertically applied to the end face of the test piece through the out-of-plane extension tooling to simulate the out-of-plane fatigue load;

[0011] The ultra-high temperature radiation loading module is arranged to fit the end surface of the test piece, which can ensure the constancy of the loading temperature while providing high temperature loading.

[0012] A further technical solution of the present invention is: the test piece is a cross-shaped multi-layer thermal protection structure, including a heat protection layer, a heat insulation layer and a cold structure layer arranged in sequence, wherein the heat protection layer serves as a high-temperature loading surface and is opposite to and in contact with the ultra-high temperature radiation loading module, and the heat protection layer is longer at the end of the cross than the heat protection layer and the heat insulation layer, and is used to connect an in-plane extension clamp.

[0013] A further technical solution of the present invention is: the in-plane extension fixture includes a positioning plate, a fixing plate and a cooling channel, one end of the positioning plate is connected to the in-plane loading module as a loading end, and the other end is connected to the end of the heat protection layer of the test piece as a force-applying end; the force-applying end of the positioning plate is provided with a mounting surface of the end of the heat protection layer, the fixing plate is fastened to the mounting surface of the end of the heat protection layer by a fastener, and the end of the heat protection layer is clamped and fixed between the force-applying end of the positioning plate and the fixing plate to realize the in-plane extension of the end of the heat protection layer; the cooling channel is connected to a water cooler to reduce heat transfer of the in-plane extension fixture.

[0014] A further technical solution of the present invention is: the in-plane loading module is a multi-axis fatigue testing machine, including loading heads arranged in the positive and negative directions of XY in the plane, the four loading heads are respectively connected to the four ends of the test piece through in-plane extension clamps, and the loading directions are respectively parallel to the extension directions of the four ends.

[0015] A further technical solution of the present invention is: the out-of-plane extension tooling includes a vertical plate, which is arranged perpendicular to the end faces of the test piece on both sides, and reinforcing ribs are arranged on both sides; the first vertical plate located on one side of the cold structure layer is vertically fixed to the cross center of the cold structure layer; there are two second vertical plates located on one side of the heat protection layer, which are respectively vertically fixed to two oppositely arranged in-plane extension fixture surfaces; the out-of-plane loading force applied to the test piece by the out-of-plane loading module is received by the vertical plates arranged at both ends of the test piece.

[0016] A further technical solution of the present invention is: the out-of-plane loading module has a traction rope and weights, one end of the traction rope is connected to the vertical plate, and the other end is connected to the weights, and the out-of-plane loading force of the test piece can be adjusted by increasing or decreasing the number of weights or changing the specifications.

[0017] A further technical solution of the present invention is: the ultra-high temperature radiation loading module comprises a shell and an electromagnetic induction coil arranged therein; a through hole is provided on one side wall of the shell, and a silicon carbide heating plate is installed in the through hole, a high temperature resistant insulation board is fixed on the shell wall located at the periphery of the through hole, and a 25 mm channel is opened on the high temperature resistant insulation board to form a heating window, the channel entrance is opposite to the silicon carbide heating plate, and the channel exit is opposite to the test piece; the heating temperature of the silicon carbide heating plate by the electromagnetic induction coil is controlled by a temperature control box, and the heat is transferred to the test piece through the channel to complete the high temperature loading;

[0018] The inner wall of the shell is provided with a water cooling pipe which is connected to a water cooler to reduce the temperature of the shell through circulating water.

[0019] A further technical solution of the present invention is: further comprising a collection module, wherein the collection module comprises an in-plane multi-axis force displacement data collection module, a temperature collection module and a strain collection module;

[0020] The in-plane multi-axis force displacement data acquisition module is arranged on the multi-axis fatigue testing machine, and performs data acquisition while loading;

[0021] The temperature acquisition module is composed of an S-type thermocouple and an infrared thermal imager; there are 4 S-type thermocouples, one of which is installed at the center of the radiated heating surface and is responsible for feeding back the temperature of the test piece to the temperature control box, thereby realizing fine temperature control; two are installed at the central area where the thermal insulation layer and the heat protection layer meet; and one is installed on the outer surface of the cold structure layer; the infrared thermal imager is used to measure the temperature of the entire field, and the S-type thermocouple is used to verify its data to ensure the accuracy of the measured temperature;

[0022] The strain acquisition module uses high temperature DIC for measurement.

[0023] A further technical solution of the present invention is: it also includes a fixed module as a frame structure, the top of which is slidably connected to the shell of the ultra-high temperature radiation loading module through a slide rail; and a support frame is arranged on the top of the frame to support and limit the force direction of the traction rope.

[0024] A multi-layer thermal protection structure ultra-high temperature multi-axial force and thermal coupling test method, the specific steps are as follows:

[0025] The test piece is fixedly connected to four loading heads of the in-plane loading module through four in-plane extension clamps;

[0026] Install the ultra-high temperature radiation loading module on the fixing module, and adjust its position so that the heating window fits the radiation heating surface of the test piece;

[0027] Starting each module of the ultra-high temperature multi-axial force-thermal coupling test system of the multi-layer thermal protection structure to carry out a loading test;

[0028] The real-time collected measurement data is fed back to the host computer through the in-plane multi-axis force displacement data acquisition module to adjust the loading force;

[0029] The temperature acquisition module feeds back the real-time measurement data to the temperature control box to adjust the loading current and achieve precise control of the loading temperature.

[0030] The global strain of the test piece is measured through the strain acquisition module.

[0031] Beneficial Effects

[0032] The beneficial effects of the present invention are as follows: the present invention combines an in-plane loading module with an out-of-plane loading module, and by designing a special fixture and tooling, it is possible to simultaneously apply in-plane and out-of-plane loading forces to the test piece, and the loading force can be flexibly and accurately adjusted; at the same time, the ultra-high temperature radiation loading module is arranged on the side of the radiated heating surface of the test piece, and the ultra-high temperature loading of small test pieces can be achieved based on the design of its heating window; therefore, the present invention can conduct a principle test of the ultra-high temperature multi-axial force-thermal coupling response characteristics of the multi-layer protective structure that is close to the actual application scenario, thereby ensuring the test accuracy and providing real reference data for the actual application of the multi-layer protective structure. The specific advantages are analyzed as follows:

[0033] 1. The present invention adopts an ultra-high temperature radiation heating module, which can implement accurate thermal load simulation on small multi-layer thermal protection structures and realize single-sided radiation heating. This heating method is highly similar to the single-sided aerodynamic heating conditions experienced by the outer surface of a hypersonic vehicle, thereby ensuring the accuracy and reliability of the test results. Based on electromagnetic induction driven silicon carbide heating plate radiation rapid heating, the heating rate can be adjusted within 5-15°C / s, and the maximum operating temperature can reach 1500°C. In addition, compared with quartz lamp radiation heating, the present invention can operate stably for a long time in an ultra-high temperature environment (i.e., 1250 degrees Celsius).

[0034] 2. The present invention adopts the above-mentioned multi-axial load simulation module, which can ensure that under the condition of high-temperature single-sided thermal load, the in-plane multi-axial fatigue load and the out-of-plane static load of the test piece can be loaded at the same time, which is more in line with actual working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the test device of the present invention;

[0036] Figure 2 is a schematic diagram of an ultra-high temperature radiation heating module of the present invention;

[0037] Figure 3 is a schematic diagram of a small multi-axial test piece of the present invention;

[0038] Figure 4 It is a schematic diagram of the connection between the in-plane extension clamp 20 of the present invention and the temperature cooling module;

[0039] Figure 5 Schematic diagram of the connection between the in-plane extension type fixture 20 of the present invention and the test piece;

[0040] Explanation of the reference numerals: 1. Fixing module, 2. Ultra-high temperature radiation heating module, 3. Multi-axis fatigue testing machine 3, 4. Weights, 5. Traction rope, 6. Water-cooling pipe, 7. Loading head, 8. Support frame, 9. Heating window, 10. High temperature resistant insulation board (mullite), 11. Corridor, 12. Heat protection layer (ceramic-based composite material), 13. Insulation layer (carbon aerogel), 14. Cold structure layer (titanium alloy cold structure), 15. Water-cooling channel, 16. Out-of-plane extension tooling, 17. Fixing plate, 18. Positioning plate, 19. Test piece, 20. In-plane extension fixture. DETAILED DESCRIPTION

[0041] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0043] Based on the existing aviation structure testing requirements and the limitations of current tests, in order to ensure the authenticity and accuracy of the simulation, the system designed by the present invention must strictly meet the following four conditions when applying the thermal load: first, the thermal load must be applied to the test piece on one side to simulate the heating conditions of the aircraft during actual flight; second, the thermal load must be able to change rapidly over time to reflect the various thermal environments that the aircraft may encounter during flight; third, the thermal load temperature must be high enough, reaching above 1200 degrees Celsius, to ensure that the test can cover the extreme high temperature environment that the aircraft may encounter; finally, the test system must be able to operate stably for a long time under ultra-high temperature conditions to ensure the reliability and effectiveness of the test results.

[0044] In terms of applying external force loads, the following three key conditions need to be met: first, the external force load must meet the requirements of multi-axis loading to simulate the various complex stress states that hypersonic vehicles may encounter during actual use; second, static and fatigue loads need to be able to be loaded simultaneously to comprehensively evaluate the performance of the thermal protection structure under multiple loads; finally, ensure that the application of external force loads during the test is stable and controllable to ensure the accuracy of the test results.

[0045] At the same time, full-scale structural thermal tests have the disadvantages of large scale, high energy consumption, high cost, and high requirements for measurement and control technology. In contrast, small-scale structural equivalent tests show obvious advantages. They can effectively reduce test costs, significantly shorten test cycles, and speed up model development. Therefore, the proposed scheme must fully meet the requirements of small test pieces to ensure its effectiveness and feasibility in practical applications. The implementation of this scheme is expected to overcome the many limitations of full-scale structural thermal tests and bring important breakthroughs and progress to research and development in related fields.

[0046] Based on the above problems and requirements, the present invention proposes an ultra-high temperature multi-axial force thermal coupling test system for a multi-layer thermal protection structure, including an in-plane loading module, an out-of-plane loading module and an ultra-high temperature radiation loading module loaded on a test piece; the in-plane loading module is connected to the periphery of the test piece through an in-plane extension fixture, and the multi-axial loading force applied by the in-plane loading module is transmitted to the test piece along a set direction through the in-plane extension fixture to simulate the in-plane fatigue load; the out-of-plane loading module is connected to the end face of the test piece through an out-of-plane extension fixture, and the loading force of the out-of-plane loading module is vertically applied to the end face of the test piece through the out-of-plane extension fixture to simulate the out-of-plane fatigue load; the ultra-high temperature radiation loading module is fitted with the end face of the test piece, which can provide high temperature loading while ensuring the constancy of the loading temperature. Through the combination of the three loading modules, the ultra-high temperature multi-axial force thermal coupling test of the multi-layer thermal protection structure is completed, and real and accurate test data can be obtained.

[0047] The above technical solution is further described below with reference to the accompanying drawings and examples:

[0048] In one embodiment, a multiaxial thermal fatigue test is performed on a small test piece of a ceramic matrix composite multilayer thermal protection structure in an ultra-high temperature environment. Figure 1 As shown, the test system used for testing includes an in-plane loading module, an out-of-plane loading module, an ultra-high temperature radiation loading module, an acquisition module, and a fixing module, wherein the in-plane loading module is a multi-axis fatigue testing machine 3, and the multi-axis fatigue testing machine 3 includes four loading heads 7 arranged in the positive and negative directions of XY; the out-of-plane loading module includes a traction rope 5 and a weight 6; and the ultra-high temperature radiation loading module 2 is slidably installed on the fixing module 1.

[0049] In one embodiment, referring to Figure 3 As shown, the test piece includes a multi-layer thermal protection structure of a heat protection layer 12, a heat insulation layer 13 and a cold structure layer 14, wherein the heat protection layer adopts a needle-punched ceramic-based composite material made by Northwestern Polytechnical University, and its surface is covered with a layer of SiC coating by chemical vapor deposition technology, the heat insulation layer adopts carbon aerogel produced by the National University of Defense Technology, and the cold structure adopts TC2 alloy.

[0050] In one embodiment, the in-plane extension clamp 20 is made of Inconel 718 nickel-based high-temperature alloy, which can maintain excellent strength and stability at high temperatures. Bolts made of the same material as the clamp are used to connect the clamp and the test piece. At the same time, the design of the in-plane extension clamp 20 adopts a unique dovetail clamp structure, which can significantly increase the friction between the clamp and the test piece, thereby effectively reducing the stress concentration phenomenon at the edge of the test piece hole and reducing the shear force on the bolt.

[0051] In one embodiment, the fixing module 1 is a frame-type bracket constructed of 50*50 aluminum alloy profiles, the bottom of which is fixed to the ground by bolts to ensure the stability of the bracket. The main function of the bracket is to fix the ultra-high temperature radiation heating module and the out-of-plane loading module by bolts to ensure that they maintain a stable and accurate position during use.

[0052] In one embodiment, a temperature cooling module is also included, and the temperature cooling module includes a water cooler. Figure 4 As shown, the water cooler is connected to the ultra-high temperature radiation heating module 3 and the in-plane extension clamp 20 through water cooling pipes and supporting equipment, thereby ensuring that the outer surface temperature of the ultra-high temperature radiation heating module 3 is maintained at room temperature and the temperature of the loading head 7 of the multi-axis fatigue testing machine 3 is stabilized below 100 degrees Celsius.

[0053] In one embodiment, referring to Figure 2 As shown, the ultra-high temperature radiation heating module 3 includes a silicon carbide heating plate, an electromagnetic induction coil, a temperature control box, a high temperature resistant insulation board 10 and a shell. The core working principle of the module is to realize efficient electromagnetic heating of the silicon carbide heating plate by passing a high frequency current into the electromagnetic induction coil. In the internal structure of the ultra-high temperature radiation heating module, the high temperature resistant insulation board 10 is designed as a 25mm long heat flow channel, which can not only withstand ultra-high temperature environment, but also effectively ensure that the heat loss during the transfer process is as small as possible. The silicon carbide heating plate is placed at one end of the channel, and the test piece is close to the other end of the channel. Such a structural design ensures that the heat generated by the silicon carbide heating plate can pass through the channel smoothly and directly reach the surface of the test piece. In this way, single-sided ultra-high temperature radiation heating of the test piece can be achieved. This feature enables the ultra-high temperature radiation heating module to highly realistically simulate the real environment in which the multi-layer heat protection structure on the hypersonic aircraft is subjected to aerodynamic heating on one side during hypersonic flight. At the same time, an S-type thermocouple is installed at the center of the test piece to collect temperature signals in real time and transmit them to the temperature control box. The temperature control box intelligently adjusts the current in the heating coil according to the received temperature signal, and then accurately controls the heat generated by the silicon carbide heating plate to achieve the two purposes of rapid heating and fine temperature control. The temperature control box has a number of configurable parameters, including heating rate, maximum temperature and temperature holding time, to meet the flexible adjustment and precise control requirements of different heat loads.

[0054] In one embodiment, the high temperature resistant insulation board is made of mullite and the outer shell is made of 304 stainless steel.

[0055] When a hypersonic vehicle is flying, the multi-layer thermal protection structure on the vehicle is not only subjected to the above-mentioned ultra-high temperature loads, but also to the multi-axial dynamic and static fatigue loads in the plane and the tensile stress from the high-speed incoming flow on the multi-layer thermal protection structure. In order to more realistically simulate the actual working conditions of a hypersonic vehicle during flight, a multi-axis load simulation module is set up.

[0056] In one embodiment, the multi-axis load simulation module is composed of several parts such as a multi-axis fatigue testing machine and an out-of-plane load simulation module. The multi-axis fatigue testing machine adopts the ZYSS series dual-axis servo dynamic and static material testing machine produced by Changchun Mechanical Science Research Institute Co., Ltd. The in-plane multi-axis load spectrum can be obtained according to the actual flight conditions of the hypersonic vehicle during the flight. The out-of-plane load is applied through the out-of-plane load simulation module, which uses the pulley on the fixed module to convert the gravity of the weight into a horizontal pulling force, which is applied to the multi-layer thermal protection structure, and the applied out-of-plane load is changed by changing the mass of the weight.

[0057] In one embodiment, the data acquisition module is divided into an in-plane multi-axis force displacement data acquisition module, a temperature acquisition module, and a strain acquisition module. Among them, the in-plane multi-axis load displacement data is collected by the above-mentioned multi-axis fatigue testing machine. The temperature acquisition module consists of an S-type thermocouple and an infrared thermal imager. There are 4 S-type thermocouples, one is installed in the center of the radiated heating surface, responsible for feeding back the temperature of the test piece to the temperature control box, thereby realizing fine temperature control; two are installed in the central area where the insulation layer and the heat protection layer meet; and one is installed on the outer surface of the cold structure. The infrared thermal imager is used to measure the temperature of the entire field. Since there may be errors in the temperature measurement of the infrared thermal imager, an S-type thermocouple is used to verify its data to ensure the accuracy of the measured temperature. The strain acquisition module uses high-temperature DIC for measurement.

[0058] In one embodiment, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test method comprises the following specific steps:

[0059] First, the multi-axial fatigue testing machine 3 is connected to the test piece 19 via the in-plane extending fixture 20 , and an in-plane multi-axial fatigue load can be applied to the test piece 19 via the control system of the multi-axial fatigue testing machine 3 .

[0060] Secondly, the ultra-high temperature radiation heating simulation module 3 is moved to a predetermined position so that the outlet of the high temperature corridor 11 is closely fitted to the heating area of ​​the test piece 19 , thereby achieving single-sided high temperature radiation to the test piece 19 .

[0061] At the same time, the temperature of the center of the radiation surface of the test piece 19 is measured by a thermocouple, and the temperature signal is transmitted to the temperature control box in real time. The temperature control box flexibly adjusts the current in the high-frequency coil according to the received temperature signal, thereby achieving precise temperature control.

[0062] Next, the out-of-plane load applying module is connected to the fixing module 1 by bolts, and the mass of the weight 4 is adjusted to control the magnitude of the out-of-plane load.

[0063] Finally, the temperature cooling system is connected to the fixture and the ultra-high temperature radiation heating module to ensure that the outer surface temperature of the ultra-high temperature radiation heating module is maintained at room temperature and the temperature of the testing machine chuck is stabilized below 100 degrees Celsius.

[0064] The global strain of the specimen was obtained by high-temperature digital image correlation (DIC) technology, and the surface temperature of the specimen was measured by an S-type thermocouple and an infrared thermal imager.

[0065] Before the formal test, it is necessary to adjust the position of the fixed module and fix it to the ground with bolts. The ultra-high temperature radiation heating module and the multi-axis load module are also fixed to the appropriate positions of the fixed module with bolts to ensure the accuracy of the relative position between the two modules and the test piece, so that the two modules can function normally.

[0066] The fatigue load is applied by a multi-axis fatigue testing machine, and the mass of the weight used for the out-of-plane load condition is 45kg; the temperature load is controlled by the temperature control box of the ultra-high temperature radiation heating module, and the heating rate is set to 10℃ / s, the maximum temperature is 1250℃, and the temperature holding time is 1000s. During the above test process, the strain data of the surface of the test piece is obtained using a DIC non-contact strain measurement system, the temperature of 5 points is obtained using a thermocouple, and the global temperature field of the surface of the test piece is obtained using an infrared thermal imager. After each test, the test piece needs to be cooled to room temperature, and the above test process is repeated until the test piece breaks.

[0067] Based on the principle test method established by the present invention, mainly for small test pieces of multi-layer thermal protection structures, in-depth multi-axis mechanical and thermal coupling test research in ultra-high temperature environment is carried out. This test method can not only reveal the thermodynamic response characteristics of the multi-layer thermal protection structure under different multi-axis load conditions and thermal loads, but also further evaluate its mechanical and thermal damage under repeated mechanical and thermal loads. More importantly, due to the miniaturization of the test piece design, when it is necessary to increase the test conditions, the test cost can be greatly reduced, thereby obtaining more abundant test data and significantly improving the experimental efficiency. This innovation provides a more solid test support and data foundation for the application of multi-layer thermal protection structures in hypersonic aircraft, and is expected to significantly accelerate the development process of related models and provide strong guarantees for practical applications.

[0068] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. An ultra-high temperature multi-axial force-thermal coupling test system for a multi-layer thermal protection structure, characterized in that: It includes an in-plane loading module, an out-of-plane loading module and an ultra-high temperature radiation loading module loaded on the test piece; The in-plane loading module is connected to the periphery of the test piece through an in-plane extension fixture, and the multi-axial loading force applied by the in-plane loading module is transmitted to the test piece along a set direction through the in-plane extension fixture to simulate the in-plane fatigue load; The out-of-plane loading module is connected to the end face of the test piece through an out-of-plane extension tooling, and the loading force of the out-of-plane loading module is vertically applied to the end face of the test piece through the out-of-plane extension tooling to simulate the out-of-plane fatigue load; The ultra-high temperature radiation loading module is arranged to fit the end surface of the test piece, which can ensure the constancy of the loading temperature while providing high temperature loading.

2. According to claim 1, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system is characterized by: The test piece is a cross-shaped multi-layer thermal protection structure, including a heat protection layer, a heat insulation layer and a cold structure layer arranged in sequence, wherein the heat protection layer serves as a high-temperature loading surface and is opposite to and in contact with the ultra-high temperature radiation loading module, and the heat protection layer is longer at the end of the cross than the heat protection layer and the heat insulation layer, and is used to connect the in-plane extension clamp.

3. According to claim 2, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system is characterized by: The in-plane extension fixture includes a positioning plate, a fixing plate and a cooling channel, one end of the positioning plate is connected to the in-plane loading module as a loading end, and the other end is connected to the end of the heat protection layer of the test piece as a force-applying end; the force-applying end of the positioning plate is provided with a mounting surface of the end of the heat protection layer, the fixing plate is fastened to the mounting surface of the end of the heat protection layer by fasteners, and the end of the heat protection layer is clamped and fixed between the force-applying end of the positioning plate and the fixing plate, so as to realize the in-plane extension of the end of the heat protection layer; the cooling channel is connected to a water cooler to reduce the heat transfer of the in-plane extension fixture.

4. According to claim 3, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system is characterized by: The in-plane loading module is a multi-axis fatigue testing machine, including loading heads arranged in the positive and negative directions of XY in the plane, the four loading heads are respectively connected to the four ends of the test piece through in-plane extension fixtures, and the loading directions are respectively parallel to the extension directions of the four ends.

5. According to claim 4, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system is characterized by: The out-of-plane extension tooling includes a vertical plate, which is arranged perpendicular to the end faces of the test piece on both sides and has reinforcing ribs on both sides; the first vertical plate located on one side of the cold structure layer is vertically fixed to the cross center of the cold structure layer; there are two second vertical plates located on one side of the heat protection layer, which are vertically fixed to two oppositely arranged in-plane extension fixture surfaces; the out-of-plane loading force applied to the test piece by the out-of-plane loading module is received by the vertical plates arranged at both ends of the test piece.

6. According to claim 5, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system is characterized by: The out-of-plane loading module has a traction rope and weights, one end of the traction rope is connected to the vertical plate, and the other end is connected to the weights. The out-of-plane loading force of the test piece can be adjusted by increasing or decreasing the number of weights or changing the specifications.

7. According to claim 6, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system, characterized in that: The ultra-high temperature radiation loading module includes a shell and an electromagnetic induction coil arranged therein; a through hole is provided on one side wall of the shell, and a silicon carbide heating plate is installed in the through hole, a high temperature resistant insulation board is fixed on the shell wall located at the periphery of the through hole, and a 25 mm channel is opened on the high temperature resistant insulation board to form a heating window, the channel entrance is opposite to the silicon carbide heating plate, and the channel exit is opposite to the test piece; the heating temperature of the silicon carbide heating plate by the electromagnetic induction coil is controlled by a temperature control box, and the heat is transferred to the test piece through the channel to complete the high temperature loading; The inner wall of the shell is provided with a water cooling pipe which is connected to a water cooler to reduce the temperature of the shell through circulating water.

8. According to claim 7, a multi-layer thermal protection structure ultra-high temperature multi-axial force thermal coupling test system is characterized by: It also includes a collection module, which includes an in-plane multi-axis force displacement data collection module, a temperature collection module and a strain collection module; The in-plane multi-axis force displacement data acquisition module is arranged on the multi-axis fatigue testing machine, and performs data acquisition while loading; The temperature acquisition module is composed of an S-type thermocouple and an infrared thermal imager; there are 4 S-type thermocouples, one of which is installed at the center of the radiated heating surface and is responsible for feeding back the temperature of the test piece to the temperature control box, thereby realizing fine temperature control; two are installed at the central area where the thermal insulation layer and the heat protection layer meet; and one is installed on the outer surface of the cold structure layer; the infrared thermal imager is used to measure the temperature of the entire field, and the S-type thermocouple is used to verify its data to ensure the accuracy of the measured temperature; The strain acquisition module uses high temperature DIC for measurement.

9. The ultra-high temperature multi-axial force-thermal coupling test system of a multi-layer thermal protection structure according to claim 8, characterized in that: It also includes a fixed module as a frame structure, the top of which is slidably connected to the shell of the ultra-high temperature radiation loading module through a slide rail; and a support frame is arranged on the top of the frame to support and limit the force direction of the traction rope.

10. A method for ultra-high temperature multi-axial force-thermal coupling test of a multi-layer thermal protection structure, characterized in that The specific steps are as follows: The test piece is fixedly connected to four loading heads of the in-plane loading module through four in-plane extension clamps; Install the ultra-high temperature radiation loading module on the fixing module, and adjust its position so that the heating window fits the radiation heating surface of the test piece; Start each module of the ultra-high temperature multi-axial force-thermal coupling test system for the multi-layer thermal protection structure described in claim 9 to perform a loading test; The real-time collected measurement data is fed back to the host computer through the in-plane multi-axis force displacement data acquisition module to adjust the loading force; The temperature acquisition module feeds back the real-time measurement data to the temperature control box to adjust the loading current and achieve precise control of the loading temperature. The global strain of the test piece is measured through the strain acquisition module.

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