A CBC universal core level launch vehicle full rocket modal test free boundary suspension system

Abstract

The application provides a CBC universal core level launch vehicle full rocket modal test free boundary suspension system, through designing an innovative scheme of eight-point independent controllable suspension, the force state of a binding point between a rocket booster and a core level is controlled, the load distribution at the binding point in a real flight state is simulated, and therefore problems such as the common lack of modal simulation capability for a complex force transmission path between the core level and the booster by using a traditional support mode are solved. While ensuring the force safety of a test product, the mechanical environment of the force state of the binding point in actual flight which cannot be simulated in ground tests is avoided, and the accuracy of full rocket modal characteristics obtained by the modal test is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of aerospace full-rocket / aircraft modal testing technology, specifically relating to a suspension system for the free boundary of the CBC universal core stage launch vehicle full-rocket modal testing. Background Technology

[0002] Full-rocket modal testing, a crucial ground verification step in the development of launch vehicles, focuses on accurately simulating the dynamic boundaries of the rocket in free flight to obtain realistic modal parameters for guiding control system design, load environment prediction, and stability analysis. With the leapfrog development of space launch capabilities towards heavier and more modular designs, new launch vehicles employing a universal core-stage (CBC) configuration have become the mainstream platform for large-scale space exploration and transportation missions. These CBC-configured rockets are massive in scale, with a total mass reaching thousands of tons. The complex dynamic coupling characteristics between their core stage and boosters present unprecedented technical challenges to simulating free boundaries in ground modal testing.

[0003] Currently, traditional free boundary simulation methods face dual bottlenecks in modal testing of heavy-lift rockets with a capacity of 1,000 tons and in terms of simulation accuracy. On the one hand, conventional elastic suspension or air spring systems are unable to stably support a 1,000-ton rocket body in a vertical state, posing risks of system instability, low-frequency drift, or local overload. On the other hand, traditional support methods generally lack the ability to simulate the complex force transmission path between the core stage and boosters. Since the force state at the binding points varies in actual flight, if this mechanical environment cannot be reproduced in ground tests, it will lead to serious distortion of the modal characteristics of the entire rocket, thereby directly affecting the accuracy of the spacecraft dynamics model and even creating hidden dangers for subsequent attitude control design and flight safety.

[0004] Therefore, developing a high-precision free boundary simulation technology applicable to thousand-ton-class CBC configuration rockets and capable of accurately simulating the stress state of their binding interfaces has become an urgent technical requirement for promoting the development of heavy-lift launch vehicles in my country. This patent aims to address this challenge by proposing an innovative scheme based on eight-point independent controllable suspension, providing key methodological support for realizing realistic simulation experiments of next-generation large-size, high-mass aerospace structures. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a suspension system for the free boundary of the CBC universal core-stage launch vehicle's full-rocket modal testing. By designing an innovative eight-point independently controllable suspension scheme, the system controls the stress state at the binding points between the rocket boosters and the core stage, simulating load distribution at these binding points under real flight conditions. This solves the problem that traditional support methods generally lack the ability to simulate the complex force transmission path between the core stage and boosters. While ensuring the safety of the test product under stress, it avoids the inability to simulate the varying mechanical environments of the binding points during actual flight, significantly improving the accuracy of obtaining full-rocket modal characteristics through modal testing.

[0006] A suspension system for the free boundary of the CBC universal core stage launch vehicle's full-rocket modal test includes a load-bearing beam, hydraulic cylinders, pull plates, spring cylinders, a connecting conversion plate, adjusting rods, a rotating mechanism, steel wire ropes, a modal test specimen, and a load-bearing frame. A pin connects the hydraulic cylinder to the load-bearing beam; a pin connects the pull plate to the hydraulic cylinder; a pin connects two spring cylinders in parallel to the pull plate; a pin connects the connecting lugs to the connecting conversion plate; a pin connects the adjusting rod to the connecting conversion plate; a pin connects the rotating mechanism to the adjusting rod; a steel wire rope suspends the rotating mechanism; the booster and core stage load-bearing frame of the rocket body are connected to the end of the steel wire rope; the test specimen is lifted by a crane and connected to the load-bearing frame to achieve free boundary simulation of the CBC universal core stage launch vehicle.

[0007] The spring cylinders are arranged in a configuration of two spring cylinders connected in parallel, forming three sets connected in series.

[0008] Furthermore, the disc springs in the spring cylinder are either single-piece mating or two or more pieces stacked together.

[0009] By adjusting the hydraulic cylinder, the suspension point can be positioned at different heights.

[0010] By keeping the hydraulic cylinders in the suspension system corresponding to the core stage stationary, and by adjusting the hydraulic cylinders in the suspension system corresponding to the booster, different force states can be achieved between the booster and the core stage binding point.

[0011] The beneficial effects of this invention are as follows: (1) By designing different installation forms of disc springs inside the spring tubes and different series and parallel numbers of spring tubes, the load-bearing capacity of the suspension system is guaranteed, and the function of elastic support is achieved; each wire rope is equipped with an adjustment rod at the upper end, so that the stress state of each wire rope is consistent.

[0012] Its beneficial effects are: it ensures uniform force distribution on the suspension system; by changing multiple sets of spring cylinders connected in series, the stiffness of the entire suspension system can be adjusted, thereby ensuring that the rigid body frequency of the test suspension system is lower than 1 / 5 of the first elastic frequency of the test piece.

[0013] (2) Each booster support frame of the rocket body has two suspension points, corresponding to two suspension systems; the core stage support frame has four suspension points, corresponding to four suspension systems. The eight-point suspension system of the CBC universal core stage launch vehicle can be controlled independently. By adjusting the extension stroke of the hydraulic cylinder, the eight suspension points can be at different heights, and the force sensor connected in series at the lower end of each hydraulic cylinder can accurately obtain the load size of each suspension point.

[0014] Its beneficial effects are as follows: by designing an eight-point suspension system and adjusting the extension of the hydraulic cylinders according to the data of the force sensors connected in series with the hydraulic cylinders, it is possible to simulate the different force states of the booster and core stage binding points of the launch vehicle design, thereby accurately obtaining the modal parameters of the binding points under different load distribution states in different flight seconds. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall suspension system of the free boundary of the CBC universal core stage launch vehicle during full-rocket modal testing; Among them, 1-bearing beam, 2-hydraulic cylinder, 3-pull plate, 4-spring cylinder, 5-connecting conversion plate, 6-adjusting rod, 7-rotation mechanism, 8-steel wire rope, 9-modal test specimen, 10-bearing frame Figure 2 This is a schematic diagram of a single suspension system. Among them, 11-upper and lower connecting plates, 12-large bolt, 1-bearing beam, 2-hydraulic cylinder, 3-pull plate, 4-spring cylinder, 13-connecting double ears, 5-connecting conversion plate, 6-adjusting rod, 7-rotating mechanism Figure 3 It is a 3D diagram of a single spring cylinder; Figure 4 This is a sectional view of a single spring cylinder; Among them, 14-spring pull rod, 15-lower connecting cover, 16-spring cylinder, 17-disc spring, 18-spring washer, 19-upper connecting cover, 20-set screw. Detailed Implementation

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection claimed by the present invention.

[0017] A suspension system for the free boundary of the full-rocket modal test of a CBC universal core stage launch vehicle consists of a load-bearing beam, hydraulic cylinder, spring cylinder, adjusting rod, steel wire rope, load-bearing frame, etc.

[0018] The overall design of the suspension system is as follows: four load-bearing beams are installed on the load-bearing structure of the modal vibration tower; hydraulic cylinders are fixed to the load-bearing beams through multiple sets of tie plates and tie rods; two hydraulic cylinders are fixed on each beam, corresponding to the two suspension systems assembled below; each suspension system connects the hydraulic cylinders and the adapter tie plate through pins; the adapter tie plate and the spring cylinder are connected through pins; multiple sets of spring cylinders can be connected in series or parallel according to actual needs, and the spring cylinders are connected to each other through pins; the spring cylinder at the end is connected to the adapter tie plate through pins; the adapter tie plate and the adjusting tie rod are connected through pins; the lower end of the adjusting tie rod is connected to the rotating mechanism; the lower end of the rotating mechanism suspends the steel wire rope through a movable pulley; the steel wire rope is connected to the load-bearing frame of the test specimen; finally, the modal test specimen is connected to the load-bearing frame.

[0019] Each of the eight suspension systems is independently controlled. By adjusting the extension stroke of the hydraulic cylinders, the eight suspension points can be positioned at different heights. By keeping the hydraulic cylinders in the suspension system corresponding to the core stage stationary and adjusting the hydraulic cylinders in the suspension system corresponding to the booster, different force states between the booster and the core stage binding point can be achieved. That is, the booster uses different forces to support the core stage, and similarly, the core stage uses different forces to support the booster. Based on the above adjustment method, the different force states between the booster and the core stage binding point designed for the launch vehicle can be simulated. The force sensor connected in series at the lower end of the hydraulic cylinder can accurately obtain the load magnitude, thereby accurately simulating the load distribution state of the binding point under different flight seconds, which effectively ensures the smooth implementation of the CBC universal core stage launch vehicle modal test.

[0020] Specifically, such as Figure 2 As shown, large bolts 12 are used to connect the upper and lower connecting plates 11 to the load-bearing beam 1; a pin is used to connect the hydraulic cylinder 2 to the lower connecting plate 11; a pin is used to connect the pull plate 3 to the hydraulic cylinder 2; a pin is used to connect two spring cylinders 4 in parallel to the pull plate 3; then two sets of spring cylinders 4 are used in series with the previous set of spring cylinders to form a configuration of three sets in series with two spring cylinders in parallel; a pin is used to connect the connecting lugs 13 to the connecting conversion plate 5; a pin is used to connect the adjusting rod 6 to the connecting conversion plate 5; a pin is used to connect the rotating mechanism 7 to the adjusting rod 6; at this point, the assembly of a single suspension system is completed; as described above, a total of eight suspension systems are assembled.

[0021] like Figure 1 As shown, eight suspension systems are installed on the modal vibration tower bearing structure; steel wire ropes 8 are suspended on the rotating mechanism of the above eight suspension systems; the booster and core stage bearing frame 10 of the rocket body are connected to the end of the steel wire ropes 8; the height of each steel wire rope 8 is adjusted by adjusting the tie rod 6 to achieve the same height of each steel wire rope in a suspension system, thereby ensuring the consistent stress on the steel wire ropes; finally, the test piece 9 is lifted by a crane and connected to the bearing frame to realize the free boundary simulation of the CBC universal core stage launch vehicle.

[0022] The elastic support in the suspension system is achieved by spring cylinder 4, the specific three-dimensional shape of which is shown in the appendix. Figure 3 The internal structure is shown in the appendix. Figure 4 Disc spring 17, under external load, can compress and deform, thus providing elastic support. The installation method of disc spring 17 can be freely changed according to the self-weight of the modal test specimen, as shown in the attached figure. Figure 4 The number of steel wire ropes can be changed depending on whether the suspension system is single-piece or double-piece or multi-piece.

[0023] By changing multiple sets of spring cylinders connected in series, the stiffness of the entire suspension system can be adjusted, thereby ensuring that the rigid body frequency of the test suspension system is lower than 1 / 5 of the first elastic frequency of the test piece. The eight suspension systems are each controlled independently. By adjusting the extension stroke of the hydraulic cylinders, the eight suspension points can be positioned at different heights. The core support frame of the rocket body has four suspension points, corresponding to four suspension systems; The booster support frame has two suspension points, corresponding to two suspension systems. Since the CBC universal core stage launch vehicle has two universal boosters, the boosters in total correspond to four suspension systems. The complete suspension layout is shown in the attached figure. Figure 1 As shown; By keeping the hydraulic cylinders in the suspension system corresponding to the core stage stationary, and by adjusting the hydraulic cylinders in the suspension system corresponding to the booster, different force states can be achieved between the booster and the core stage binding point. That is, the booster uses different forces to support the core stage, and similarly, the core stage can use different forces to support the booster. Based on the above adjustment method, different force states of the booster and core stage binding points of the launch vehicle can be simulated. The force sensor connected in series at the lower end of the hydraulic cylinder can accurately obtain the load size, thereby accurately simulating the load distribution state of the binding points under different flight seconds. The above describes a complete suspension system capable of achieving free boundary conditions during full-rocket modal testing of the CBC universal core-stage launch vehicle. Because it replaces the traditional suspension method used in ground-based modal testing, it solves the safety problem of large-scale structural elastic support faced in the full-rocket modal testing of the CBC universal core-stage launch vehicle. Simultaneously, it can accurately simulate the load distribution state of the binding points under different flight-second conditions, reducing the risk of data errors introduced by inconsistencies between ground and space conditions, and effectively ensuring the smooth implementation of the CBC universal core-stage launch vehicle modal testing.

[0024] Examples using this suspension system: After the test setup was completed, the system was able to accurately simulate the load distribution at the binding points. By adjusting the stroke of the hydraulic cylinder extension, modal parameters of the first two lateral bends of a certain type of CBC launch vehicle were collected under different stress conditions at the binding points. Tables 1 and 2 show that the frequency of the "booster and core stage pitch direction swing" mode is most affected by the stress condition at the binding points, increasing from 3.66Hz in the unstressed state to 4.26Hz in the 40T stress state, a frequency change rate of 16.39%. Analysis suggests that in the "booster and core stage pitch direction swing" mode, the core stage and booster themselves are rigid bodies, and the swing between them is achieved through the main binding point connection. This reflects the mode of the binding point; different stress conditions correspond to different connection stiffnesses, thus resulting in a significant frequency change. Other modes are less affected by this connection stiffness, with the largest modal frequency change being only 1.20%, corresponding to the "one bend-yaw" mode.

[0025] Table 1 Modal parameters of the binding point under different stress states Note: The "unstressed state" of the binding point refers to the two booster load-bearing frame suspension points in the suspension system each bearing approximately the weight of the booster and load-bearing frame, while the core stage suspension point bears the weight of the core stage and load-bearing frame. Therefore, the binding point is considered to be in a basically unstressed state. The "20T load state" refers to the two booster load-bearing frame suspension points in the suspension system each bearing approximately the weight of the booster and load-bearing frame plus 20T, while the core stage suspension point bears the remaining weight. The "40T load state" refers to the two booster load-bearing frame suspension points in the suspension system each bearing approximately the weight of the booster and load-bearing frame plus 40T, while the core stage suspension point bears the remaining weight. In the "20T load state" and "40T load state," in the unstressed state, different stress conditions between the binding points are achieved by raising the load-bearing hydraulic cylinder at the top of the booster while the load-bearing hydraulic cylinder at the top of the core stage remains stationary (i.e., the booster lifts the core stage).

[0026] Table 2. Variation of modal parameters at the binding point under different stress states Finally, it should be noted that the above description is only a preferred embodiment and not a limitation. Those skilled in the art can make many modifications, variations or equivalents under the guidance of this invention without departing from the spirit and scope defined by the claims, but all such modifications, variations or equivalents will fall within the protection scope of this invention.

Claims

1. A CBC generic core level launch vehicle full vehicle modal test free boundary suspension system, characterized by, Includes a load-bearing beam, hydraulic cylinder, tie plate, spring cylinder, connecting conversion plate, adjusting tie rod, rotating mechanism, wire rope, modal test specimen, and load-bearing frame; pins connect the hydraulic cylinder to the load-bearing beam; pins connect the tie plate to the hydraulic cylinder; pins connect two spring cylinders in parallel to the tie plate; pins connect the connecting lugs to the connecting conversion plate; pins connect the adjusting tie rod to the connecting conversion plate. The rotating mechanism is connected to the adjusting rod using pins. The steel wire rope is suspended on the rotating mechanism; the booster and core stage support frame of the rocket body are connected to the end of the steel wire rope. The test specimen was lifted by a crane and connected to the load-bearing frame to simulate the free boundary of the CBC universal core stage launch vehicle.

2. The suspension system for the free boundary of the full-rocket modal test of the CBC universal core stage launch vehicle according to claim 1, characterized in that, The spring cylinders are arranged in a configuration of two spring cylinders connected in parallel, forming three sets connected in series.

3. The suspension system for the free boundary of the full-rocket modal test of a CBC universal core stage launch vehicle according to claim 2, characterized in that, The disc springs in the spring cylinder are either single-piece mating or two or more pieces stacked together.

4. The suspension system for the free boundary of the full-rocket modal test of the CBC universal core stage launch vehicle according to claim 1, characterized in that, By adjusting the hydraulic cylinder, the suspension point can be positioned at different heights.

5. The suspension system for the free boundary of the full-rocket modal test of the CBC universal core stage launch vehicle according to claim 1, characterized in that, By keeping the hydraulic cylinders in the suspension system corresponding to the core stage stationary, and by adjusting the hydraulic cylinders in the suspension system corresponding to the booster, different force states can be achieved between the booster and the core stage binding point.

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