Free boundary supporting system for horizontal modal test of large rocket

Abstract

The invention provides a free boundary supporting system for a horizontal modal test of a large rocket. The free boundary supporting system at least comprises a rack car, a pressure container, a free membrane type air spring and a control assembly. The rack car at least comprises a bottom truss and a top truss, and the bottom truss is provided with a moving device; the pressure container is specifically a gas storage container located between the bottom truss and the top truss, and the top of the pressure container is provided with a sealing flange connector. The free membrane type air spring is arranged on the upper end face of the top truss, the bottom of the free membrane type air spring communicates with the pressure container through the sealing flange connector, and a bracket used for supporting a rocket is arranged on the top of the free membrane type air spring. The control assembly at least comprises an acquisition module, a controller and an execution module which are in communication connection in sequence; freedom degrees of translation, rotation and torsion of the rocket in a modal test are provided by the free membrane type air spring.

Description

Technical Field

[0001] The present invention relates to the technical field of space launch vehicles, and particularly to a free boundary support system for horizontal mode tests of large rockets. Background Art

[0002] During the launch and flight of a launch vehicle, it will experience a complex vibration environment. To ensure the stability and reliability of the rocket structure, it is necessary to conduct modal tests on the ground to obtain modal parameters such as the natural frequency, damping ratio, and vibration mode of the rocket. However, the rocket is in a free boundary condition during flight, and it is difficult to fully simulate this environment in ground tests. Currently, elastic ropes are generally used in the industry to suspend the rocket to simulate the boundary conditions of free flight of the rocket. Existing horizontal mode test methods have technical difficulties such as large excitation difficulty, inconsistent response sizes due to uneven mass distribution, and difficulty in identifying dense modes. Therefore, in order to obtain the dynamic characteristic parameters of the large launch vehicle structure, it is urgent to develop a free boundary simulation system suitable for horizontal mode tests of large launch vehicles. Summary of the Invention

[0003] To solve the above technical problems, the present invention proposes a free boundary support system for horizontal mode tests of large rockets. By simulating the vibration characteristics of the rocket under free boundary conditions, the problems in the prior art are solved, and the accuracy and reliability of the modal test are improved.

[0004] The present invention provides a free boundary support system for horizontal mode tests of large rockets, which at least includes a gantry, a pressure vessel, a free membrane air spring, and a control component. The gantry at least includes a bottom truss and a top truss, and the bottom truss is provided with a moving device; the pressure vessel is specifically a gas storage container located on the lower end face of the top truss, and its top is provided with a sealed flange interface; the free membrane air spring is arranged on the upper end face of the top truss, its bottom is communicated with the pressure vessel through the sealed flange interface, and its top is provided with a bracket for supporting the rocket; the control component at least includes an acquisition module, a controller, and an execution module that are communicatively connected in sequence; the degrees of freedom of translation, rotation, and torsion during the modal test of the rocket are all provided by the free membrane air spring.

[0005] After the test starts, the controller sends at least a preset pressure to the execution module. The execution module adjusts the pressure of the free diaphragm spring to the preset pressure, and after collecting the actual pressure of the free diaphragm air spring through the acquisition module, sends it to the controller. The controller compares the actual pressure with the preset pressure. If the actual pressure exceeds the preset pressure by a certain range, it controls the execution module to deflate the free diaphragm air spring. If the actual pressure does not reach the preset pressure, it controls the execution module to inflate the free diaphragm air spring, thereby adjusting the load-bearing capacity and stiffness of the free diaphragm air spring.

[0006] In one embodiment, the bracket includes a middle part and two side parts connected to the middle part on both sides of the middle part. The middle part of the bracket is connected to the top of the free diaphragm air spring, and the side parts of the bracket are set as arc-shaped structures adapted to the outer shape of the rocket.

[0007] In one embodiment, the present invention further includes a limiting device arranged on both sides of the bracket along the first direction. The limiting device at least includes a first rigid structure, a first adjusting rod, and a first flexible structure. The first rigid structure is installed on the top truss, and the first adjusting rod is installed at one end of the first rigid structure away from the top truss. One end of the first flexible structure is connected to the first adjusting rod, and the other end is connected to the middle part of the bracket. By controlling the first adjusting rod to move along the first direction, the elongation and tension degree of the first flexible structure are adjusted.

[0008] Further, the first rigid structure includes a side-bending truss, a limiting plate, and an extension truss. The first end of the side-bending truss is installed on the top truss, and the second end faces the middle part of the bracket. The limiting plate is arranged at the second end of the side-bending truss. One end of the extension truss is connected to the back of the side-bending truss, and the other end installs the first adjusting rod. One end of the first flexible structure is connected to the first adjusting rod, and the other end passes through the limiting plate and is connected to the middle part of the bracket.

[0009] In one embodiment, the present invention further includes a lateral elastic support device arranged on both sides of the bracket along the second direction. The lateral elastic support device at least includes a second rigid structure, a second adjusting rod, and a second flexible structure. The second rigid structure is arranged on the top truss, and the second adjusting rod is installed at one end of the first rigid structure away from the top truss. One end of the second flexible structure is connected to the second adjusting rod, and the other end is connected to the side part of the bracket. By controlling the second adjusting rod to move along the second direction, the elongation and tension degree of the second flexible structure are adjusted.

[0010] In any of the above embodiments, the acquisition module at least includes a pressure sensor and a height regulating valve provided on the free diaphragm air spring, and a laser displacement sensor provided on the upper end surface of the top truss; the pressure sensor is used to detect the pressure change of the free diaphragm air spring; the height regulating valve is used to dynamically sense the direct height change of the free diaphragm air spring; the laser displacement sensor measures the position change of the bracket by laser to obtain the indirect height change of the free diaphragm air spring; the controller calculates the actual pressure of the free diaphragm air spring based on the collected pressure change data, direct height change data, and indirect height change data.

[0011] In one embodiment, the pressure vessel is provided with an inflation hole, and an inflation valve is externally connected to the inflation hole to inflate the pressure vessel, and the pressure of the pressure vessel is measured by a pressure gauge; a safety valve is provided at the top of the pressure vessel, and a drain valve is provided at the bottom.

[0012] In one embodiment, the top surfaces of the two sides of the bracket are used to support the rocket, and a protective baffle is provided on the bottom surface; one end of the second flexible structure is connected to the second adjusting rod, and the other end is connected to the protective baffle; a buffer pad is provided at one end of the protective baffle away from the bracket.

[0013] In one embodiment, the acquisition module further includes an inertial measurement unit provided on the side surface of the middle of the bracket, and the inertial measurement unit is used to measure the acceleration of the bracket in linear motion and the angular velocity in rotational motion.

[0014] In one embodiment, the moving device includes a traveling device, a braking device, and a locking device provided on the bottom truss; after the moving device transfers the support system to the test site through the traveling device, it is braked by the braking device, and the vehicle is locked and fixed by the locking device.

[0015] The free boundary support system for the horizontal modal test of a large rocket provided by the present invention has at least one of the following beneficial effects:

[0016] First, the present invention uses the non-linear characteristics and variable stiffness characteristics of the air spring to simulate the free boundary of the modal test, ensuring that the natural vibration frequency remains almost unchanged under the conditions of axial and radial loading, so that the free boundary support system has almost unchanged characteristics, approximately simulating the free boundary in the rocket flight state. In addition, the present invention upgrades the suspension to support, saving the test cost and test cycle.

[0017] Second, the present invention effectively improves the accuracy and reliability of modal tests. This support system can accurately simulate the dynamic response of a rocket under free boundary conditions, eliminating the errors caused by traditional boundary conditions, thereby greatly improving the accuracy of modal tests and the reliability of test results.

[0018] Third, the present invention can adjust the air spring stiffness according to pressure changes, reducing a large amount of physical simulation and complex adjustments in traditional tests, increasing test flexibility, shortening the test cycle, and reducing test costs.

[0019] Fourth, the present invention can be quickly adjusted according to different rocket models and test requirements, greatly enhancing the flexibility and adaptability of tests. It can simulate a variety of complex flight environments and boundary conditions, providing the possibility for a comprehensive performance evaluation of rockets.

[0020] After reading the specific implementation manners and viewing the drawings, those skilled in the art will recognize additional features and advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is a schematic diagram of a free boundary support system of an embodiment of the present invention supporting a rocket.

[0023] Figure 2 It is a schematic diagram of the overall structure of a free boundary support system of an embodiment of the present invention

[0024] Figure 3 It is a schematic diagram of the control flow of a control component of a free boundary support system of an embodiment of the present invention.

[0025] Figure 4 It is a schematic diagram of the structure of a free diaphragm air spring of an embodiment of the present invention.

[0026] Figure 5 It is a schematic diagram of the structure of a limiting device of an embodiment of the present invention.

[0027] Figure 6 It is a schematic diagram of the structure of a lateral elastic support device of an embodiment of the present invention.

[0028] Figure 7 It is a schematic diagram of the structure of a bracket of an embodiment of the present invention.

[0029] Figure 8It is an enlarged view of the free diaphragm type air spring part of the embodiment of the present invention. Detailed implementation manners

[0030] The features of various aspects of the present invention and exemplary embodiments will be described in detail below. To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are used to exemplarily illustrate the principles of the present invention, and are not configured to limit the present invention. In addition, the components in the drawings are not necessarily drawn to scale. For example, the sizes of some components or regions in the drawings may be enlarged for other components or regions to help understand the embodiments of the present invention.

[0031] The orientation terms appearing in the following descriptions are all the directions shown in the drawings and do not limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that unless otherwise specified, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0032] In addition, the terms "including", "comprising", "having" or any other variants thereof are intended to cover non-exclusive inclusion, so that a series of elements, structural parts or components include not only those elements, but also other structural parts or components that are not explicitly listed or are inherent in the structural parts and components. Without further limitations, the elements defined by the statement "including..." do not exclude the existence of additional identical elements in the articles or devices including the elements.

[0033] Spatial relationship terms such as "below", "beneath", "under", "low", "above", "on", "high", etc. are used to facilitate the description and explain the positioning of one element relative to a second element. These terms are intended to cover different orientations of the device, except for those orientations different from those shown in the drawings. In addition, for example, "one element is on / under another element" may mean that the two elements are in direct contact or that there are other elements between the two elements. In addition, terms such as "first", "second", etc. are also used to describe each element, region, part, etc., and should not be regarded as limiting. Similar terms represent similar elements throughout the description.

[0034] For those skilled in the art, the present invention can be implemented without some of these specific details. The following description of the embodiments is only provided to provide a better understanding of the present invention by showing examples of the present invention.

[0035] During flight, the rocket is under free boundary conditions, and it is difficult to fully simulate this environment in ground tests, so only an approximate simulation can be carried out. For horizontal modal tests, theoretically, the actual state of the aircraft in flight in the air needs to be simulated on the ground. This state is an unconstrained state, that is, the so-called "free-free" state, which is simply impossible to achieve in practice. The usual approach is to use springs, flexible suspensions, etc. to obtain an approximate free-free system. In order to minimize the influence of the elastic support elements on the measurement of the modal parameters of the aircraft, it is necessary to use as soft elastic elements as possible, so that the rigid body natural frequency of the specimen vibrating on the elastic support elements is as low as possible, that is, to minimize the stiffness of the elastic support elements.

[0036] In the existing simulation of free boundaries, components such as cylindrical springs, disc springs, rubber ropes, and air cushions are mostly used. The designed single-group bearing capacity of the support is low, its natural vibration frequency is fixed and non-adjustable, and the lowest natural vibration frequency can only be reduced to about 0.6 Hz. As the volume and weight of the product increase, the elastic frequency decreases, and then the required free boundary rigid body frequency decreases accordingly. Therefore, there are great difficulties in simulating the free boundary of the horizontal modal test of large liquid rockets. Aiming at the deficiencies of the existing technology, the technical problem to be solved by the present invention is to provide a free boundary simulation device for the horizontal modal test of large liquid rockets. This device can simulate the free boundary in the horizontal state, ensure that the additional mass and additional stiffness are within the engineering allowable range for boundary simulation, effectively increase the effectiveness, safety and stability of free boundary simulation, and more accurately obtain the vibration characteristics of the rocket structure, and reduce the test cost.

[0037] See Figure 1 、 Figure 2 、 Figure 3 and Figure 4, a free boundary support system for horizontal mode tests of a large rocket provided by the present invention at least includes a car body 1, a pressure vessel 2, a free diaphragm air spring 3, and a control component 4. Among them, the car body 1 serves as the installation foundation of the entire support system and at least includes a bottom truss 11 and a top truss 12. The bottom truss 11 is provided with a moving device facilitating the transfer of the support system between various sites. The pressure vessel 2 is specifically a gas storage vessel located between the bottom truss 11 and the top truss 12, and its top is provided with a sealed flange interface for connecting with the free diaphragm air spring 3. The free diaphragm air spring 3 is arranged on the upper end surface of the top truss 12, and its bottom communicates with the pressure vessel 2 through the sealed flange interface, so that the pressure in the free diaphragm air spring 3 is kept consistent with that in the pressure vessel 2. The bottom of the free diaphragm air spring 3 is also connected to the top truss 12 by bolts, and a bracket 5 for supporting the rocket is arranged at the top. The translational, rotational, and torsional degrees of freedom of the rocket located on the bracket 5 during the mode test are all provided by the free diaphragm air spring 3, and all six degrees of freedom of the free diaphragm air spring 3 are released, realizing the simulation of the free boundary in the horizontal state.

[0038] The control component 4 at least includes an acquisition module 41, a controller 42, and an execution module 43 that are communicatively connected in sequence. The acquisition module 41 at least acquires the pressure data of the free diaphragm air spring 3 and sends it to the controller 42. After receiving the data and making a judgment, the controller 42 issues an action instruction to the execution module 43 to inflate or deflate the free diaphragm air spring 3 through the execution module 43.

[0039] Specifically, before the mode test starts, two free boundary support systems of the present invention are placed in a spaced-apart columnar arrangement, and the test rocket 10 is placed above the two free support boundary systems 9A and 9B. Each set of free support boundary systems can work independently without interference. After the test starts, first, the controller 42 sends a preset pressure to the execution module 43, and the execution module 43 is used to inflate the free diaphragm spring 3 to adjust its pressure to the preset pressure. At the same time, the acquisition module 41 acquires the actual pressure of the free diaphragm air spring 3 and sends it to the controller 42. The controller 42 compares the actual pressure with the preset pressure. If the actual pressure exceeds the preset pressure by a certain range, it controls the execution module 43 to deflate the free diaphragm air spring 3; if the actual pressure does not reach the preset pressure, it controls the execution module 43 to inflate the free diaphragm air spring 3. The above process will proceed synchronously with the mode test until the test ends, so that the bearing capacity and stiffness of the free diaphragm air spring 3 can be adaptively adjusted according to different pressures, effectively and accurately simulating the free boundary conditions, and can also be quickly adjusted according to different rocket models and test requirements, greatly enhancing the flexibility and adaptability of the test.

[0040] The free membrane air spring 3 in the embodiments of the present invention is a flexible sealed shock-absorbing element, which is a composite formed by vulcanizing rubber and metal, and at least includes an upper end plate 31, a lower end plate 32, and a rubber bladder 33. The upper end plate 31 is fixedly connected to the bracket 5, and a part of the lower end plate 32 is fixedly connected to the top truss 12, and the other part is connected to the sealing flange interface of the pressure vessel 2 to realize the communication between the pressure vessel 2 and the rubber bladder 33. The free boundary support system in this embodiment inflates the rubber bladder 33 through the pressure vessel 2, so as to provide stiffness for the free membrane air spring 3. The stiffness of a commonly used ordinary steel spring is a fixed value, so its natural vibration frequency changes with the change of load, while the air spring has non-linear characteristics, and the stiffness changes with the change of load, so the natural vibration frequency is almost unchanged under any load.

[0041] See also Figure 2 、 Figure 3 、 Figure 5 、 Figure 6 and Figure 7 In one embodiment, the bracket 5 is an aluminum thin-walled welded structure, and its top is an arc-shaped smooth connecting surface for supporting the rocket body. The bracket 5 at least includes a middle part 51 and two side parts (the first side part 52 and the second side part 53) connected to the middle part 51 from both sides of the middle part 51. The middle part 51 of the bracket 5 is connected to the upper end 31 of the free membrane air spring 3, and the two side parts of the bracket 5 are arranged as arc-shaped structures adapted to the outer shape of the rocket.

[0042] To increase the support reliability, the free boundary support system in the embodiments of the present invention further includes a limiting device 6 arranged on both sides of the bracket 5 along the first direction S1. The limiting device 6 at least includes a first rigid structure 61, a first adjusting rod 62, and a first flexible structure 63. The first rigid structure 61 is installed on the top truss 12, the first adjusting rod 62 is installed at one end of the first rigid structure 61 away from the top truss 1, one end of the first flexible structure 63 is connected to the first adjusting rod 62, and the other end is connected to the middle part 51 of the bracket 5. To facilitate the connection of the first flexible structure 63, interfaces for connecting the first flexible structure 63 are arranged on both sides of the middle part 51 of the bracket in the first direction S1.

[0043] The free boundary support system in this embodiment can cooperate with adjusting the limiting devices on both sides of the bracket. By controlling the first adjusting rod 62 to move it along the first direction S1, the elongation and tension of the corresponding first flexible structure 63 can be adjusted until the bracket 5 is in a neutral position in the first direction S1. The limiting device in this embodiment can also limit the excessive deviation of the bracket and the rocket from the test position along the first direction S1 in the form of flexible support during the modal test.

[0044] Furthermore, the free boundary support system of the embodiment of the present invention further includes lateral elastic support devices 7 arranged on both sides of the bracket 5 along the second direction S2. The lateral elastic support device 7 at least includes a second rigid structure 71, a second adjusting rod 72, and a second flexible structure (not marked in the figure). The second rigid structure 71 is arranged on the top truss 12, and the second adjusting rod 72 is installed at one end of the first rigid structure 71 away from the top truss 12. One end of the second flexible structure is connected to the second adjusting rod 72, and the other end is connected to the side of the bracket 5. The tops of the two sides (side 51 and side 52) of the bracket 5 are used to support the rocket, and protective baffles 54 are respectively arranged at the bottoms of side 51 and side 52 near the middle 51. The second flexible structure 73 is connected to the bracket 5 through the protective baffle 54 to support the bracket 5 and keep the bracket 5 in a neutral position in the second direction S2. In addition, a buffer pad is arranged on the end face of the bottom (the end away from the bracket) of the protective baffle 54 to provide protection when the bracket 5 contacts the top truss 12. When the rocket rotates excessively along the second direction S2 during the modal test, the end face of the protective baffle 54 provided with the buffer pad contacts the top truss 12, so that the maximum rotation angle of the bracket and the rocket in this direction can be limited, and the bracket is protected from damage.

[0045] In the free boundary support system of this embodiment, the two lateral elastic support devices can be adjusted respectively, the corresponding second adjusting rod 72 is controlled to move along the second direction S2, and then the elongation and tension degree of the corresponding second flexible structure 73 are adjusted until the bracket 5 is in a neutral position in the second direction S2. The lateral elastic support device in this embodiment can also limit the excessive deviation of the bracket and the rocket from the test position along the second direction S2 in the form of flexible support during the modal test.

[0046] Furthermore, the first rigid structure 61 includes a side-bending truss 611, a limit plate 612, and an extension truss 613. The first end of the side-bending truss 611 is installed on the top truss 12, the second end is arranged towards the middle 51 of the bracket 5, and the limit plate 613 is arranged at the second end of the side-bending truss 611. One end of the extension truss 613 is connected to the back of the side-bending truss 611, and the other end is installed with a first adjusting rod 62. Among them, the limit plate 612 is provided with a limit hole along the direction towards the middle 51 of the bracket. One end of the first flexible structure 63 is connected to the first adjusting rod 62, and the other end passes through the limit hole of the limit plate 612 and is connected to the middle 51 of the bracket. The inner wall of the limit hole of the limit plate 612 will limit the movement amount of the first flexible structure 63, so that the movement range of the middle 51 of the bracket can be restricted, and the limit ability of the limit device in this embodiment in more degrees of freedom is improved.

[0047] In the above embodiments, the free boundary support system of the present invention can limit and protect the bracket and the rocket in the directions of all degrees of freedom through the combined use of the lateral elastic support device and the limiting device. It can not only ensure that the heights of the bracket and the test rocket do not exceed the limit value, but also guarantee the safety of the bracket and the test rocket in the test suspension state.

[0048] In any of the above embodiments, the way to adjust the elongation of the first adjusting rod and the second adjusting rod can be handwheel adjustment or servo motor adjustment.

[0049] In addition, the volume of the pressure vessel in this embodiment is not less than 300L. After the pressure vessel is connected to the free diaphragm air spring, the air chamber space of the free diaphragm air spring is enlarged. The stiffness of the air spring can be adjusted by changing the gas medium in the pressure vessel. The pressure vessel is provided with an inflation hole, and the inflation hole is externally connected to an inflation valve. The inflation of the pressure vessel is realized by controlling the opening of the inflation valve. At the same time, the pressure of the pressure vessel is measured by a screw-connected pressure gauge. A safety valve is also provided at the top of the pressure vessel, and a drain valve is provided at the bottom. Among them, the safety valve is threadedly connected to the pressure vessel and is located at the top of the pressure vessel, and the drain valve is threadedly connected to the pressure vessel and is located at the bottom of the pressure vessel.

[0050] See Figure 2 、 Figure 3 and Figure 8 , in an embodiment, the acquisition module 41 of the embodiment of the present invention at least includes a pressure sensor (not marked in the figure) and a height regulating valve 411 arranged on the side of the free diaphragm air spring 3, and a laser displacement sensor 412 arranged on the upper end surface of the top truss 12. The pressure sensor is a static gauge pressure sensor. When subjected to an external pressure, the strain gauge deforms, thereby changing its resistance value. By measuring the change in the resistance value, the magnitude of the force can be deduced to realize the monitoring of the pressure of the free diaphragm air spring. The height regulating valve 411 is used to dynamically sense the direct height change of the free diaphragm air spring 3 and can timely complete the actions of intake or exhaust to adjust the height of the free diaphragm air spring 3. The laser displacement sensor 412 is a high-precision sensor that measures the position and deformation of an object through laser. By emitting laser and collecting the reflected light, the position of the light spot on the CCD array is calculated through trigonometric functions, so as to obtain the distance between the object and the sensor. When using the free boundary support system of this embodiment to support the rocket for a horizontal modal test, the pressure sensor, the height regulating valve, and the laser displacement sensor respectively transmit the collected data to the controller. The controller calculates the actual pressure of the free diaphragm air spring based on the received data, compares the calculated actual pressure with the preset pressure, and issues corresponding action instructions to the execution module according to the comparison result.

[0051] The acquisition module 41 of this embodiment further includes an inertial measurement unit 413 disposed on the side of the middle part 51 of the bracket 5. The inertial measurement unit 413 is used to measure the acceleration of the bracket during linear motion and the angular velocity during rotational motion, so as to quickly identify the position deviation of the bracket and the rocket during the test.

[0052] The control element of the embodiment of the present invention has a dual-backup structure. The control strategy mainly adopts a pressure control system with a fuzzy PID algorithm, and at the same time uses height control as an auxiliary control strategy, with a height regulating valve as the control element. The fuzzy PID control algorithm is to combine the fuzzy control algorithm and the PID control algorithm in series, which is equivalent to real-time tuning of the control parameters of the PID controller through the fuzzy control algorithm. Specifically as follows: Real-time tuning of the proportional coefficient of the PID controller can adjust the response time of the control system, improve the overshoot of the system, and enhance the stability of the system; Real-time tuning of the integral coefficient of the PID controller can avoid the over-strong cumulative integral effect when the deviation is too large, thus causing instability of the control system; Real-time tuning of the differential coefficient of the PID controller can effectively suppress the overshoot of the control system without affecting the response speed of the system at the beginning of the control.

[0053] In any of the above embodiments, the vehicle carrier is a truss structure with functions of loading, walking, braking, and locking. The moving device disposed on the bottom truss at least includes a walking device, a braking device, and a locking device. Among them, one end of the walking device is bolted to the bottom truss and the other end is in contact with the ground. The walking device can enable the vehicle carrier to walk axially freely relative to the ground. Braking devices are arranged at the four corners of the bottom truss, and the braking devices are provided with a plurality of hydraulic brake diaphragms. The locking device at least includes an L-shaped workpiece connected to one end of the bottom truss. The other end of the L-shaped workpiece is provided with a plurality of long slots, and a plurality of handwheels are arranged at the long slots. The handwheels can move in the up and down directions to realize the locking of the vehicle carrier and the ground.

[0054] Before the test starts, the entire support system can be transferred to the test site by using the walking device. After the transfer is in place, it is braked by using the braking device, and the vehicle carrier is locked in the test area through the locking device, so as to facilitate the horizontal modal test of the rocket. After the test is over, the rocket is removed, the locking device is unlocked, and the free boundary support system is pushed away from the test area by using the walking device.

[0055] The above embodiments can be combined with each other and have corresponding technical effects.

[0056] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A free boundary support system for horizontal modal test of large rockets, characterized in that: At least: A frame vehicle, comprising at least a bottom truss and a top truss, wherein the bottom truss is provided with a moving device; The pressure vessel is specifically a gas storage container located at the lower end surface of the top truss, and a sealing flange interface is provided on the top of the pressure vessel; A free film air spring is arranged on the upper end surface of the top truss, the bottom of which is connected to the pressure vessel through the sealing flange interface, and the top of which is provided with a bracket for supporting the rocket; The control component comprises at least a collection module, a controller and an execution module which are communicatively connected in sequence; The degrees of freedom of translation, rotation and torsion of the rocket during modal testing are all provided by the free film air spring; after the test starts, the controller sends a preset pressure to the execution module, and the pressure of the free film spring is adjusted to the preset pressure by the execution module, and the actual pressure of the free film air spring is collected by the collection module and sent to the controller; the controller compares the actual pressure with the preset pressure, and if the actual pressure exceeds the preset pressure by a certain range, controls the execution module to deflate the free film air spring, and if the actual pressure does not reach the preset pressure, controls the execution module to inflate the free film air spring, thereby adjusting the load-bearing capacity and stiffness of the free film air spring.

2. The large rocket horizontal modal test free boundary support system according to claim 1, characterized in that: The bracket includes a middle portion and two side portions connected to the middle portion from both sides of the middle portion; the middle portion of the bracket is connected to the top of the free membrane air spring, and the side portions of the bracket are configured to be an arc-shaped structure adapted to the outer surface of the rocket.

3. The large rocket horizontal modal test free boundary support system according to claim 2, characterized in that: It also includes a limiting device arranged on both sides of the bracket along the first direction; The limiting device at least comprises a first rigid structure, a first adjusting rod and a first flexible structure; the first rigid structure is mounted on the top truss, and the first adjusting rod is mounted on an end of the first rigid structure away from the top truss; one end of the first flexible structure is connected to the first adjusting rod, and the other end is connected to the middle of the bracket; The first adjusting rod is controlled to move along the first direction to adjust the elongation and tension of the first flexible structure.

4. The large rocket horizontal modal test free boundary support system according to claim 3, characterized in that: It also includes lateral elastic support devices arranged on both sides of the bracket along the second direction; The lateral elastic support device at least comprises a second rigid structure, a second adjustment rod and a second flexible structure; the second rigid structure is arranged on the top truss, and the second adjustment rod is installed on an end of the first rigid structure away from the top truss; one end of the second flexible structure is connected to the second adjustment rod, and the other end is connected to the side of the bracket; The second adjusting rod is controlled to move along the second direction to adjust the elongation and tension of the second flexible structure.

5. The large rocket horizontal modal test free boundary support system according to claim 4, characterized in that: The first rigid structure includes a side bending truss, a stopper plate and an extension truss; the first end of the side bending truss is mounted on the top truss, the second end is arranged toward the middle of the bracket, and the stopper plate is arranged at the second end of the side bending truss; one end of the extension truss is connected to the back of the side bending truss, and the other end is installed with the first adjustment rod; One end of the first flexible structure is connected to the first adjusting rod, and the other end thereof passes through the limiting plate and is connected to the middle portion of the bracket.

6. The large rocket horizontal modal test free boundary support system according to any one of claims 1 to 5, characterized in that: The acquisition module at least includes a pressure sensor and a height regulating valve arranged on the free film air spring, and a laser displacement sensor arranged on the upper end surface of the top truss; The pressure sensor is used to detect the pressure change of the free film air spring; the height regulating valve is used to dynamically sense the direct height change of the free film air spring; the laser displacement sensor measures the position change of the bracket by laser to obtain the indirect height change of the free film air spring; The controller calculates the actual pressure of the free film air spring through the collected pressure change data, direct height change data and indirect height change data.

7. The large rocket horizontal modal test free boundary support system according to claim 6, characterized in that: The pressure vessel is provided with an inflation hole, the inflation hole is externally connected to an inflation valve to inflate the pressure vessel, and the pressure of the pressure vessel is measured by a pressure gauge; The top of the pressure vessel is provided with a safety valve, and the bottom is provided with a drain valve.

8. The large rocket horizontal modal test free boundary support system according to claim 4, characterized in that: The top surfaces of the two side portions of the bracket are used to support the rocket, and the bottom surface is provided with a protective baffle; one end of the second flexible structure is connected to the second adjustment rod, and the other end is connected to the protective baffle; A buffer pad is arranged at one end of the protection baffle away from the bracket.

9. The large rocket horizontal modal test free boundary support system according to claim 6, characterized in that: The acquisition module also includes an inertial measurement unit arranged on the side of the middle part of the bracket, and the inertial measurement unit is used to measure the acceleration of the bracket in linear motion and the angular velocity of the bracket in rotational motion.

10. The large rocket horizontal modal test free boundary support system according to claim 1, characterized in that: The mobile device includes a traveling device, a braking device and a locking device which are arranged on the bottom truss; after the mobile device transfers the support system to the test site through the traveling device, it stops by using the braking device, and locks and fixes the frame vehicle by using the locking device.

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