Adaptive energy absorption and vibration reduction system and vibration reduction method for aircraft ground take-off and landing platform

Abstract

This invention discloses an adaptive energy absorption and vibration reduction system and method for an aircraft ground takeoff and landing platform. The movement of the upper shell towards the lower shell drives the fan wheel to rotate, and the permanent magnet is immersed in a magnetorheological fluid, causing the apparent viscosity of the fluid to increase and converting the impact kinetic energy into heat energy for dissipation. The worm gear, connecting shaft, and worm can rotate in the magnetic field generated by the permanent magnet, cutting magnetic field lines and inducing eddy currents. In this invention, when the upper shell moves towards the lower shell, the fan wheel rotation converts the impact kinetic energy of the lower shell's landing into fluid shear heat and eddy current heat when the upper shell displacement is large. When the upper shell displacement is small, the vibration reduction mechanism, mainly based on eddy current damping, broadens the vibration reduction frequency band, achieving full-band coverage from severe impacts to fine vibration isolation, and is adaptable to eVTOL aircraft of different tonnages and landing speeds.

Description

Technical Field

[0001] This invention relates to the field of vertical take-off and landing (VTOL) aircraft infrastructure technology, and more specifically to an adaptive energy absorption and vibration reduction system and method for aircraft ground take-off and landing platforms. Background Technology

[0002] Electric Vertical Take-Off and Landing (eVTOL) aircraft, as an important carrier of future urban air mobility (UAM), are characterized by vertical take-off and landing, low noise, environmental friendliness, and operational flexibility. They are considered an important technological approach to alleviating urban traffic congestion and building a three-dimensional transportation system. With the rapid development of the eVTOL industry, the demand for its supporting infrastructure is increasing. Among these, the take-off and landing platform, as a crucial facility for aircraft take-off, landing, and parking operations, directly affects the operational safety of the aircraft and the long-term service capability of the platform due to its structural safety, operational reliability, and vibration damping performance.

[0003] During the landing process of eVTOL aircraft, the landing platform will be subjected to significant impact loads and vibrations due to factors such as the aircraft's own weight, load variations, descent velocity fluctuations, and environmental wind disturbances. Especially under conditions of high-frequency operation, mixed operation of multiple aircraft types, and complex meteorological environments, the platform not only needs to withstand instantaneous impact energy but also requires excellent vibration isolation capabilities and structural durability. Therefore, developing efficient energy-absorbing and vibration-damping devices to improve the platform's ability to buffer and absorb impact loads and suppress vibrations has become an important research direction in the field of eVTOL landing infrastructure.

[0004] Currently, common aircraft damping and vibration reduction technologies are mainly applied to traditional aircraft or helicopter landing gear systems, often employing spring damping, rubber damping, hydraulic damping, or combinations thereof to absorb impact energy. For example, patent document EP2607232A1 discloses a vibration absorption device for helicopter landing gear, which reduces aircraft vibration transmission through a tuned mass damper (TMD) structure. This technology can achieve good suppression of vibrations within a specific frequency range, but its vibration reduction performance depends on pre-designed inherent frequency parameters. When the aircraft's mass, load state, or external excitation frequency changes, detuning can easily occur, leading to a decrease in vibration reduction effectiveness. Due to the characteristics of eVTOL aircraft, such as large load variations and complex operating conditions during operation, this type of passive vibration reduction device with fixed parameters is difficult to meet the damping and vibration reduction requirements of complex landing environments.

[0005] Furthermore, patent application CN120517634A discloses a "TLD vibration damping platform for large UAV take-off and landing." This technology constructs a vibration damping system by setting a tuned liquid damper (TLD) tank under the take-off and landing platform, combined with a self-resetting compression rod, support spring, and connecting device. The system utilizes the lateral force generated by the sloshing of liquid within the tank to dissipate the vibration energy generated during UAV take-off and landing, while the compression rod and support device absorb some of the impact load, thus suppressing the vibration of the take-off and landing platform. Although this solution can reduce the horizontal vibration and vertical impact generated during the take-off and landing of large UAVs to a certain extent, its vibration damping effect largely depends on the tuning frequency of the TLD system. The tuning frequency is mainly set by adjusting the liquid depth, making it difficult to achieve real-time dynamic adjustment based on changes in aircraft weight, landing speed, and complex environmental disturbances. In addition, TLD technology mainly targets low-frequency horizontal vibrations and has limited ability to absorb large impact loads and multi-directional coupled vibrations generated during the landing of eVTOL aircraft. Under high-frequency, multi-aircraft, and complex operating conditions, its vibration reduction performance and environmental adaptability are still somewhat insufficient.

[0006] In theoretical research, magnetorheological dampers have attracted widespread attention in the field of semi-active vibration damping due to their adjustable damping force and fast response speed. Related studies have established multiphysics simulation models of magnetorheological dampers to analyze the relationship between the damper piston speed, damping force, and control current, and explored the impact of control strategies on the system's vibration performance. The results show that adjusting the excitation current of the magnetorheological damper can achieve dynamic changes in the damping force, thereby improving the system's vibration response characteristics. However, such systems typically require auxiliary equipment such as controllers, sensors, and power supply devices, resulting in a relatively complex system structure. When facing high-energy transient impact loads generated during the landing of eVTOL aircraft, their control response speed, system reliability, and environmental adaptability still have certain limitations.

[0007] In recent years, with the deepening research on Advanced Air Mobility (AAM) and Vertical Take-off and Landing (VTOL) fields, related studies indicate that future eVTOL platforms will face application scenarios such as high-frequency take-offs and landings, multi-aircraft cooperative operations, and complex airflow disturbances. Compared with traditional aircraft take-off and landing facilities, eVTOL platforms need to withstand more frequent and complex dynamic impact loads, significantly increasing their vibration control and energy absorption requirements. Existing buffering and vibration reduction technologies are mostly optimized for single impacts or single operating conditions, and their energy absorption and vibration reduction performance under continuous impacts, multi-source vibration coupling, and random loads remains insufficient, making it difficult to meet the development needs of future urban air mobility infrastructure.

[0008] In summary, existing technologies generally suffer from problems such as fixed buffer parameters, insufficient adaptability to operating conditions, limited impact energy absorption efficiency, and difficulty in accommodating multiple aircraft types, multiple loads, and complex operating environments. Therefore, there is an urgent need to develop an energy-absorbing and vibration-damping device suitable for eVTOL takeoff and landing platforms to improve the platform's ability to buffer and absorb impact loads and suppress vibrations, enhance the platform's structural safety and operational reliability, and meet the development needs of future urban air mobility systems. Summary of the Invention

[0009] The technical problem to be solved by this invention is how to provide an energy-absorbing and vibration-damping device suitable for eVTOL take-off and landing platforms and adapt to the vibration reduction requirements of eVTOL models with different tonnages and landing speeds.

[0010] This invention solves the above-mentioned technical problems through the following technical means: an adaptive energy absorption and vibration reduction system for an aircraft ground takeoff and landing platform, including an energy absorption and vibration reduction unit. The energy absorption and vibration reduction unit includes an upper shell, a transmission assembly, a lower shell, and a stirring damping assembly. The upper shell and the lower shell are elastically connected by an elastic limiting member. The transmission assembly and the stirring damping assembly are provided within the cavity structure formed by the upper shell and the lower shell. The transmission assembly includes a gear, a rack, and a connecting shaft. The connecting shaft is rotatably connected to the inner wall of the lower shell. A rack is fixedly connected to the inner wall of the upper shell. A gear that meshes with the rack is fixedly connected to the connecting shaft. The stirring damping assembly... The assembly includes a worm gear fixed coaxially with the gear, a worm connected to the worm gear drive, and the worm gear rotatingly engaged with the inner wall of the lower housing. The upper housing has a permanent magnet extending from the bottom to the top of the upper housing at one end facing the lower housing. The lower housing is filled with magnetorheological fluid. A fan wheel is provided at the end of the worm that extends below the surface of the magnetorheological fluid. The movement of the upper housing toward the lower housing can drive the fan wheel to rotate. The permanent magnet is immersed in the magnetorheological fluid, causing the apparent viscosity of the magnetorheological fluid to increase and converting the impact kinetic energy into heat energy for dissipation. The worm gear, connecting shaft, and worm can rotate and cut magnetic field lines in the magnetic field generated by the permanent magnet and induce eddy currents.

[0011] As a preferred technical solution, the adaptive energy absorption and vibration reduction system for the aircraft ground take-off and landing platform also includes the take-off and landing platform, with multiple evenly distributed energy absorption and vibration reduction units at the bottom of the take-off and landing platform.

[0012] As a preferred technical solution, the take-off and landing platform is the ground take-off and landing platform for the eVTOL aircraft.

[0013] As a preferred technical solution, the lifting platform is connected and fastened to the upper shell by bolts. The upper shell is provided with a spring groove that is compatible with the elastic connecting member, and the inner wall of the top of the spring groove is provided with a mounting hole.

[0014] As a preferred technical solution, a support rib is fixedly connected to the inner wall of one side of the lower housing. A bearing is fixedly connected to the end of the support rib that is away from the inner wall of the lower housing. The bearing is rotatably engaged with the worm gear. A support rib is fixedly connected to the inner wall of the other side of the lower housing. A bearing is fixedly connected to the other end of the support rib. The bearing is rotatably engaged with the connecting shaft.

[0015] As a preferred technical solution, the upper shell is provided with guide groove 1 and guide groove 2 that are adapted to support rib 1 and support rib 2.

[0016] As a preferred technical solution, the magnetorheological fluid filling area is 40%-60% of the volume of the lower shell, causing the area in the lower shell that is not filled with magnetorheological fluid to form a gas compensation cavity.

[0017] As a preferred technical solution, two elastic limiting members are provided. The two elastic limiting members are located outside the cavity enclosed by the upper shell and the lower shell. The elastic limiting members include springs, one end of which is elastically connected to the upper shell and the other end is elastically connected to the lower shell.

[0018] As a preferred technical solution, there are two sets of support ribs, which are arranged side by side. Two sets of support ribs are arranged side by side along the transverse direction on one side inner wall of the lower shell. Each set of support ribs includes two rib plates, and each rib plate has a bearing at its end. There are two worm gears, and the two ends of each worm gear are rotatably connected by two bearings in the same set of support ribs.

[0019] This invention also provides a vibration reduction method for an adaptive energy absorption and vibration reduction system for an aircraft ground take-off and landing platform. The adaptive energy absorption and vibration reduction system for an aircraft ground take-off and landing platform also includes a take-off and landing platform, which is an eVTOL aircraft ground take-off and landing platform. The eVTOL aircraft ground take-off and landing platform is fixed on the top of the upper cover plate. When the landing gear legs of the eVTOL aircraft land and impact the eVTOL aircraft ground take-off and landing platform, the upper shell moves toward the lower shell and compresses the elastic reset component. The vertical displacement of the upper shell is converted into the rotational stirring motion of the fan wheel in the magnetorheological fluid. As the displacement of the upper shell increases, the permanent magnet gradually approaches or enters the working area of ​​the magnetorheological fluid, which increases the apparent viscosity or yield stress of the magnetorheological fluid, converting the landing impact kinetic energy into fluid shear heat, eddy current heat and structural deformation energy dissipation. The connecting shaft and the worm rotate in the magnetic field to cut the magnetic field lines, inducing the generation of auxiliary eddy currents, providing passive electromagnetic damping to dissipate vibration energy.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) In this invention, the upper shell moves toward the lower shell. When the upper shell displacement is large, the fan blades rotate and convert the impact kinetic energy borne by the lower shell into heat energy through fluid shearing and eddy current dissipation. When the upper shell displacement is small, the vibration reduction mechanism based on eddy current damping broadens the vibration reduction frequency band and achieves full-band coverage from severe impact to fine vibration isolation. It can adapt to eVTOL models with different tonnage and landing speed. At the same time, the permanent magnet is immersed in the magnetorheological fluid to generate a magnetic field. No external power supply, sensor or electronic control system is required. It relies entirely on the mechanical structure and physical field changes to achieve adaptive adjustment, which greatly improves the safety and reliability of the system in the outdoor unattended environment.

[0022] (2) In this invention, the bottom of the landing platform is provided with multiple energy-absorbing and vibration-damping units arranged in a rectangular pattern. When the eVTOL lands and there are differences in the contact time of each support point or there is a slight unevenness on the ground, the vibration-damping device that is first loaded or heavily loaded has a larger compression amount, while the vibration-damping device that is later loaded or lightly loaded has a smaller compression amount. The flexibility of the spring causes the landing platform panel to produce a slight rigid body pitch or roll. The permanent magnet increases the viscosity of the magnetorheological fluid as the upper shell moves, which increases the damping force of the unit with a large compression amount to suppress its further sinking. The damping force of the unit with a small compression amount is smaller and allows it to continue to follow up, so that the reaction force of each support point tends to be balanced. The platform panel automatically corrects the tilt angle and maintains the horizontal, realizing multi-point collaborative passive leveling. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the vibration reduction system provided in an embodiment of the present invention; Figure 2 This is a side sectional view of the vibration reduction system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of the vibration reduction system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the upper shell structure provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the lower shell structure provided in an embodiment of the present invention; Reference numerals: 1. Upper housing; 101. Spring groove; 102. Guide groove one; 103. Mounting hole; 104. Guide groove two; 2. Spring; 3. Lower housing; 301. Support rib one; 302. Bearing one; 303. Support rib two; 304. Bearing two; 4. Worm gear; 5. Connecting shaft; 6. Permanent magnet; 7. Worm; 8. Gear; 9. Magnetorheological fluid; 10. Fan wheel; 11. Rack. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] See Figure 1 An adaptive energy absorption and vibration reduction system for an eVTOL take-off and landing platform includes a take-off and landing platform (not shown) and at least one energy absorption and vibration reduction unit. The energy absorption and vibration reduction unit includes an upper shell 1, a transmission assembly, a lower shell 3, and a stirring damping assembly. The upper shell 1 and the lower shell 3 are arranged vertically opposite each other. The end of the upper shell 1 away from the lower shell 3 is fixedly connected to the bottom of the take-off and landing platform. The upper shell 1 can slide relative to the lower shell 3. In this embodiment, the upper shell 1 can slide toward or away from the lower shell 3. At least two elastic limiting members are provided between the upper shell 1 and the lower shell 3. In this embodiment, the elastic limiting members are springs 2. Two springs 2 are provided in each energy absorption and vibration reduction unit, respectively located on both sides of the upper shell 1 and the lower shell 3. See Figure 2 , Figure 3 The upper shell 1 is provided with a permanent magnet 6. One end of the permanent magnet 6 is fixed to the bottom of the upper shell 1, and the other end extends towards the upper shell 1 away from the lower shell 3, i.e., the top of the upper shell 1. The lower shell 3 is filled with magnetorheological fluid 9. The area of ​​the lower shell 3 filled with magnetorheological fluid 9 forms the magnetorheological fluid working area. It should be noted that each of the four bottom corners of the upper housing 1 is fixedly connected with an L-shaped permanent magnet 6; The transmission assembly and the stirring damping assembly are arranged in the cavity structure enclosed by the upper shell 1 and the lower shell 3. In this embodiment, the rack 11 of the transmission assembly is arranged in the upper shell 1, and the gear 8, the connecting shaft 5 and the stirring damping assembly of the transmission assembly are arranged in the lower shell 3. The stirring part extends into the magnetorheological fluid working area. The upper shell 1 is a hollow box structure, and the lower shell 3 is a hollow box structure that is sealed at the bottom and circumferentially. The transmission assembly includes a rack 11, a gear 8, and a connecting shaft 5. The connecting shaft 5 is rotatably connected to the inner wall of the lower housing 3, and the rack 11 is fixedly connected to the inner wall of the upper housing 1. The gear 8 that meshes with the rack 11 is fixedly connected to the connecting shaft 5. The stirring damping assembly includes a worm gear 4, a worm 7, and a fan wheel 10. At least one worm 7 is rotatably connected to the inner wall of the lower housing 3. A worm gear 4 that drives the worm 7 is fixedly connected to the connecting shaft 5. In this embodiment, two worm gears 4 are fixedly connected to the connecting shaft 5, and the two worm gears 4 are located on both sides of the gear 8. Two worms 7 are rotatably connected to the inner wall of the lower housing 3. Both worms 7 extend into the magnetorheological fluid working area. A fan wheel 10 is fixedly connected to one end of the worm 7 that extends into the magnetorheological fluid working area. In this embodiment, the fan wheel 10 is fixedly connected to the bottom of the worm 7.

[0026] It should be noted that the worm 7 is a double-headed large lead angle worm. The double-headed large lead angle worm and the worm wheel 4 break through the self-locking limitation of the worm wheel and worm mechanism in the existing technology, realize the reverse transmission of vertical impact into rotational stirring, and thus convert the sinking kinetic energy of eVTOL into the rotational kinetic energy of the fan wheel 10. No external motor drive is required, which simplifies the system structure. The magnetorheological fluid working area occupies 40%-60% of the volume of the lower shell 3. This semi-filled design not only ensures sufficient stirring resistance of the fan wheel 10, but also reserves a gas compensation cavity, solving the problem of sealing failure caused by thermal expansion and contraction of the liquid. At the same time, the stirring action of the fan wheel 10 effectively prevents the sedimentation of magnetorheological particles and extends the maintenance cycle.

[0027] See Figure 4 , Figure 5 The upper housing 1 has a spring groove 101 adapted to the spring 2. The upper housing 1 is fixedly connected to the lifting platform by bolts. The inner wall of the top of the spring groove 101 has a mounting hole 103 adapted to the bolt. A support rib 301 is fixedly connected to one side of the inner wall of the lower housing 3. One end of the support rib 301 is connected to the inner wall of the lower housing 3, and the other end is fixedly connected to the outer ring of the bearing 302. The worm 7 is rotatably engaged with the inner ring of the bearing 302. A guide groove 102 adapted to the support rib 301 is provided on the upper housing 1. A support rib 303 is fixedly connected to the other side of the inner wall of the lower housing 3. A bearing 304 is fixed on the support rib 303. The connecting shaft 5 passes through the inner ring of the bearing 304 and is rotatably engaged with the bearing 304. A guide groove 104 adapted to the support rib 303 is provided on the upper housing 1.

[0028] It should be noted that, in this embodiment, two sets of support ribs 301 are fixedly connected side by side along the transverse direction on one side of the inner wall of the lower housing 3. Each set of support ribs 301 includes two rib plates arranged at intervals along the vertical direction. Each rib plate is provided with a bearing 302 at one end away from the inner wall of the lower housing 3. Two support ribs 303 are fixedly connected to the other side of the inner wall of the lower housing 3. A bearing 304 is provided at one end of the support ribs 303 away from the inner wall of the lower housing 3.

[0029] When the eVTOL landing impact acts on the upper housing 1, the upper housing 1 moves downward and compresses the elastic reset assembly. At the same time, the rack 11, gear 8, connecting shaft 5, and worm gear 4 and worm 7 form a worm gear pair, which converts the vertical displacement of the upper housing 1 into the rotational stirring motion of the fan wheel 10 in the magnetorheological fluid 9. As the displacement of the upper housing 1 increases, the permanent magnet 6 gradually approaches or enters the working area of ​​the magnetorheological fluid, which increases the apparent viscosity or yield stress of the magnetorheological fluid 9. When the fan wheel 10 rotates in the high-viscosity magnetorheological fluid 9, it generates greater shear resistance and stirring power consumption, thereby converting the landing impact kinetic energy into fluid shear heat, eddy current heat and structural energy consumption. In addition, the connecting shaft 5 and worm 7 are made of good conductors. In this embodiment, the connecting shaft 5 and worm 7 are made of copper. The connecting shaft 5 and worm 7 rotate in the magnetic field and cut magnetic field lines, generating auxiliary eddy current damping. Without adding additional sensors and controllers, passive and reliable electromagnetic damping assistance is provided.

[0030] The working principle of eVTOL, from the contact platform to complete rest, is divided into four interrelated stages: Phase 1: Initial Contact and Micro-Pre-compression Phase; When the eVTOL landing gear outriggers just make contact with the landing platform, i.e., the upper housing 1, the system begins to respond to a small vertical load. At this time, the upper housing 1 generates a small displacement at the millimeter level, compressing the spring 2 to absorb the initial potential energy. Simultaneously, the permanent magnet 6 fixed to the bottom of the upper housing 1 begins to approach the magnetorheological fluid 9 inside the lower housing 3, generating an initial gradient magnetic field in the fluid, causing its apparent viscosity to increase slightly. In addition, the rack 11 drives the gear 8 and the connecting shaft 5 to begin to rotate slightly, and the worm gear 4 drives the large lead angle worm 7 and the fan wheel 10 to rotate at low speed, initially disturbing the magnetorheological fluid 9 in preparation for the subsequent large impact. Phase Two: Main Impact Absorption and Adaptive Energy Dissipation Phase; As the eVTOL is fully loaded and its sinking speed reaches its peak, the system enters the core vibration reduction stage. The upper shell 1 undergoes significant displacement relative to the lower shell 3. The rack 11 drives the gear 8 to rotate at high speed, which in turn drives the worm 7 and the fan wheel 10 to rotate at high speed through the connecting shaft 5 and the worm wheel 4. At this time, the greater the impact, the greater the displacement of the upper shell 1, the larger the working area of ​​the permanent magnet 6 in the magnetorheological fluid 9, and the higher the magnetic field strength. The apparent viscosity of the magnetorheological fluid 9 increases nonlinearly and rapidly. The resistance and power consumption of the fan wheel 10 in stirring in the high-viscosity liquid increase significantly, thereby converting most of the impact kinetic energy into heat energy for dissipation. At the same time, the worm wheel 4, the connecting shaft 5, and the worm 7 rotate in the magnetic field of the permanent magnet 6, cutting the magnetic field lines and inducing eddy currents, providing additional auxiliary electromagnetic damping, which works in conjunction with the main stirring damping. The third stage: rebound suppression and attitude leveling stage; After the main impact energy is dissipated, spring 2 begins to release potential energy in an attempt to push the upper shell 1 back. At this time, the magnetorheological fluid 9 is still in a high viscosity state, which forms a huge damping torque on the rotation of the fan wheel 10, effectively suppressing the secondary oscillation of the system. In the application scenario of multi-point support, each independent vibration damping unit will achieve adaptive differential compensation according to the actual load of its own outriggers through different compression amounts and the damping force of the magnetorheological fluid 9, ensuring the attitude stability and leveling of the eVTOL fuselage when landing at multiple support points. Phase 4: Static dwell and micro-vibration isolation phase; After the eVTOL comes to a complete stop, the system enters a static dwell state. At this time, the relative motion between the upper shell 1 and the lower shell 3 approaches zero, and the spring 2 maintains a constant compression to maintain the supporting force. Although the fan wheel 10 stops rotating, the static shear yield force established by the permanent magnet 6 in the magnetorheological fluid 9 still exists, which can effectively resist the small slippage caused by the low-frequency vibration of the rotor or the environmental wind load. At the same time, the static existence of the fan wheel 10 also helps to maintain the uniformity of particle distribution inside the magnetorheological fluid 9, providing continuous static stability support for the eVTOL.

[0031] In operation, this invention has the following significant characteristics: The greater the impact of the eVTOL, the greater the displacement of the upper housing 1, and the more the permanent magnet 6 is immersed in the magnetorheological fluid 9, resulting in a nonlinear and rapid increase in the viscosity of the liquid. At the same time, the rack 11 drives the fan wheel 10 to rotate faster. The combination of the two results in a significant increase in stirring resistance and eddy current damping. This characteristic of "great force produces great damping, and small force produces small damping" is perfectly adapted to eVTOL models with different tonnages and descent speeds. Composite damping spectrum complementarity: The stirring damping of magnetorheological fluid 9 is mainly for large-amplitude impacts at low and medium frequencies, while the eddy current damping generated by conductor cutting magnetic field lines is mainly for high-frequency micro-vibrations. The mechanism of magnetorheological fluid 9 stirring damping being the main force at large displacements and eddy current damping being the main force at small displacements or high frequencies broadens the vibration reduction frequency band and achieves full-frequency coverage from severe impacts to fine vibration isolation. The entire device requires no external power supply, sensors, or electronic control system. It relies entirely on mechanical structure and changes in physical field to achieve adaptive adjustment, which greatly improves the reliability and safety of the system in unattended outdoor environments. The bottom of the landing platform is equipped with multiple energy-absorbing and vibration-damping units. When the eVTOL descends and there are differences in the contact time of each support point or there are slight unevennesses on the ground, the vibration damping device that is loaded first or under heavy load has a larger compression amount, while the vibration damping device that is loaded later or under light load has a smaller compression amount. The flexibility of the spring 2 causes the landing platform panel to produce a slight rigid body pitch or roll. The permanent magnet 6 increases the viscosity of the magnetorheological fluid 9 as the upper shell 1 moves, which increases the damping force of the large compression unit to suppress its further sinking, while the damping force of the small compression unit is smaller and allows it to continue to follow. This makes the reaction force of each support point tend to be balanced, and the platform panel automatically corrects the tilt angle and maintains the horizontal position, realizing multi-point coordinated passive leveling.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adaptive energy absorption and vibration reduction system for an aircraft ground takeoff and landing platform, characterized in that, The system includes an energy-absorbing and vibration-damping unit, comprising an upper housing, a transmission assembly, a lower housing, and a stirring damping assembly. The upper and lower housings are elastically connected by an elastic limiting member. The cavity structure formed by the upper and lower housings houses the transmission assembly and the stirring damping assembly. The transmission assembly includes a gear, a rack, and a connecting shaft. The connecting shaft is rotatably connected to the inner wall of the lower housing, and a rack is fixedly connected to the inner wall of the upper housing. A gear meshing with the rack is fixedly connected to the connecting shaft. The stirring damping assembly includes a worm gear coaxially fixed to the gear and a drive mechanism connected to the worm gear. The worm gear is connected to the inner wall of the lower housing and rotates with it. The upper housing has a permanent magnet extending from the bottom to the top of the upper housing at one end facing the lower housing. The lower housing is filled with magnetorheological fluid. The end of the worm gear that extends below the surface of the magnetorheological fluid is equipped with a fan wheel. The movement of the upper housing toward the lower housing can drive the fan wheel to rotate. The permanent magnet is immersed in the magnetorheological fluid, which causes the apparent viscosity of the magnetorheological fluid to increase and converts the impact kinetic energy into heat energy for dissipation. The worm wheel, connecting shaft and worm gear can rotate and cut magnetic field lines in the magnetic field generated by the permanent magnet and induce eddy currents.

2. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 1, characterized in that, It also includes a landing platform, with multiple evenly distributed energy-absorbing and vibration-damping units at the bottom of the landing platform.

3. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 2, characterized in that, The take-off and landing platform is the ground take-off and landing platform for the eVTOL aircraft.

4. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 2, characterized in that, The lifting platform is fastened to the upper shell by bolts. The upper shell has a spring groove that matches the elastic connector, and the inner wall of the top of the spring groove has a mounting hole.

5. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 1, characterized in that, A support rib is fixedly connected to the inner wall of one side of the lower housing. A bearing is fixedly connected to the end of the support rib that is away from the inner wall of the lower housing. The bearing is rotatably engaged with the worm gear. A support rib is fixedly connected to the inner wall of the other side of the lower housing. A bearing is fixedly connected to the other end of the support rib. The bearing is rotatably engaged with the connecting shaft.

6. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 5, characterized in that, The upper shell is provided with guide groove 1 and guide groove 2 that are adapted to support rib 1 and support rib 2.

7. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 1, characterized in that, The magnetorheological fluid filling area is 40%-60% of the volume of the lower shell, causing the area in the lower shell not filled with magnetorheological fluid to form a gas compensation cavity.

8. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 1, characterized in that, Two elastic limiting members are provided. The two elastic limiting members are located outside the cavity enclosed by the upper shell and the lower shell. The elastic limiting members include springs, one end of which is elastically connected to the upper shell and the other end is elastically connected to the lower shell.

9. The adaptive energy absorption and vibration reduction system for aircraft ground takeoff and landing platforms according to claim 5, characterized in that, Two sets of support ribs are arranged side by side along the transverse direction on one side of the inner wall of the lower shell. Each set of support ribs includes two rib plates, and each rib plate is provided with a bearing at its end. There are two worm gears, and the two ends of each worm gear are rotatably connected by two bearings in the same set of support ribs.

10. A vibration reduction method using the adaptive energy absorption and vibration reduction system for an aircraft ground takeoff and landing platform as described in any one of claims 1-9, characterized in that, The adaptive energy absorption and vibration reduction system of the aircraft ground take-off and landing platform also includes the take-off and landing platform, which is the ground take-off and landing platform of the eVTOL aircraft. When the landing impact of the landing gear legs of the eVTOL aircraft acts on the ground take-off and landing platform, the upper shell moves towards the lower shell and compresses the elastic reset component. The vertical displacement of the upper shell is converted into the rotational stirring motion of the fan wheel in the magnetorheological fluid. As the displacement of the upper shell increases, the permanent magnet gradually approaches or enters the working area of ​​the magnetorheological fluid, which increases the apparent viscosity or yield stress of the magnetorheological fluid, converting the landing impact kinetic energy into fluid shear heat, eddy current heat and structural deformation energy dissipation. The connecting shaft and worm rotate in the magnetic field to cut the magnetic field lines, inducing the generation of auxiliary eddy currents, providing passive electromagnetic damping to dissipate vibration energy.

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