Tire structure of space vehicle and space vehicle

Abstract

The invention provides a space vehicle, relates to the technical field of spaceflight, and solves the technical problem that tires of the space vehicle are insufficient in shock resistance in an outer space environment. The tire structure comprises a metamaterial structure formed by three planar cell elements, and each planar cell element comprises four unit structures; each unit structure comprises four arc-shaped ligaments, the four ligaments are rotationally and symmetrically distributed, and each ligament is provided with a first section close to the rotation center and a second section away from the rotation center; the first sections of the four ligaments define a quadrilateral frame, and the concave sides of the four ligaments face the rotation center; the four unit structures are connected in sequence, the two adjacent second sections of each unit structure are connected with the second sections of the two adjacent unit structures respectively, and each unit structure and the two adjacent unit structures are arranged in a mirror symmetry mode; each planar cell comprises two opposite first strips which are convex outwards and two opposite second strips which are concave inwards. The tire structure has good impact resistance.

Description

Technical Field

[0001] The present invention relates to the field of space technology, and in particular to a space vehicle. Background Art

[0002] In space exploration missions, space vehicles need to cope with extreme environments and complex terrains, including irregular terrains and high impact loads on the surfaces of the moon, Mars, etc. The design of space vehicle tires needs to meet the following performance requirements: it must be able to support the weight of the space vehicle and maintain durability even on the moon where there is no gravity at all; the surface of other planets is in a vacuum state, and pneumatic tires will burst quickly, so special hollow tires are used for space vehicles; it needs to have sufficient impact resistance to withstand the impacts that may be encountered when driving on uneven surfaces. Therefore, there is an urgent need to develop a tire structure that can protect the space vehicle from surface impacts and slow down the damage of key load-bearing components under the extreme conditions of outer space. Summary of the Invention

[0003] The purpose of the present invention is to provide a space vehicle to solve the technical problem of insufficient impact resistance of the tires of existing space vehicles in the outer space environment.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a space vehicle, including a tire structure, and the tire structure includes a metamaterial structure formed by three planar unit cells, and the planar unit cell includes four unit structures;

[0006] The unit structure includes four arc-shaped ligaments, and the four ligaments are rotationally symmetrically distributed. The ligament has a first section close to the rotation center and a second section far from the rotation center; the first sections of the four ligaments enclose a quadrilateral frame, and the concave sides of the four ligaments face the rotation center;

[0007] The four unit structures are connected in sequence, and the adjacent two second sections of each unit structure are respectively connected to the second sections of the adjacent two unit structures, and each unit structure is mirror-symmetrically arranged with the adjacent two unit structures;

[0008] The planar unit cell includes two relatively outwardly convex first bands and two relatively inwardly concave second bands; the first band and the second band are respectively formed by the connected ligaments of the adjacent two unit structures;

[0009] The two planar unit cells are arranged perpendicular to each other, and the corresponding first bands of the two planar unit cells are in a cross shape;

[0010] One of the planar cells is perpendicular to both of the two mutually perpendicular planar cells, and each of the second strips is in a cross shape with the corresponding second strip of one of the two mutually perpendicular planar cells.

[0011] The centers of the three planar cells coincide.

[0012] According to at least one embodiment of the present invention, the connection line of the outer contour of the unit structure is a preset square; the ratio of the side length of the constructed square of the frame to the side length of the preset square is greater than zero and less than or equal to 0.5;

[0013] Each vertex of the constructed square is located on the center line of the corresponding first segment of the frame.

[0014] According to at least one embodiment of the present invention, in the same unit structure, there is a preset distance between the free end of the second segment and the side of the preset square passed by the free end of the adjacent second segment, and the ratio of the preset distance to the side length of the preset square is greater than zero and less than or equal to 0.5.

[0015] According to at least one embodiment of the present invention, the ratio of the width of the ligament to the side length of the preset square is greater than zero and less than or equal to 0.3.

[0016] According to at least one embodiment of the present invention, the ratio of the thickness of the ligament to the side length of the preset square is greater than zero and less than or equal to 0.3.

[0017] According to at least one embodiment of the present invention, the tire structure is obtained by spatially bending the metamaterial structure by 22.5° and arranging it in a circumferential array with a target bending radius.

[0018] According to at least one embodiment of the present invention, the tire structure is an integrally formed part.

[0019] According to at least one embodiment of the present invention, the material of the metamaterial structure includes one of nickel-titanium shape memory alloy, copper-based shape memory alloy, and iron-based shape memory alloy.

[0020] According to at least one embodiment of the present invention, the bandgap value range of the forbidden band of the metamaterial structure is 320 Hz to 375 Hz.

[0021] Among one or more technical solutions provided in the exemplary embodiments of the present invention, at least one of the following beneficial effects can be achieved.

[0022] The space vehicle of an exemplary embodiment of the present invention includes a tire structure formed of a metamaterial structure. The metamaterial structure is a three-dimensional structure composed of three planar unit cells. The three planar unit cells are respectively arranged in space parallel to the XOY plane, the YOZ plane, and the ZOX plane, and the central points of the three planar unit cells coincide. Specifically, the planar unit cell is formed by sequentially connecting four unit structures. Two adjacent ligaments of each unit structure are respectively connected to the ligaments of two adjacent unit structures, forming two outwardly convex first bands and two inwardly concave second bands. The two inwardly concave second bands are opposite to each other, and the two outwardly convex first bands are opposite to each other. The unit structure is formed by enclosing the first segments of four ligaments to form a quadrilateral frame, and the concave side of the ligament faces the rotation center.

[0023] When a load is applied to the unit structure, the deformation of each ligament causes the center (frame) of the unit structure to twist, thereby pushing the adjacent ligaments towards the center of the unit structure. Due to the action of the central twist, the ligaments also shift inward.

[0024] For the second band between two unit structures arranged symmetrically by mirror image in the above-mentioned planar unit cell, the displacements during load bearing are superposed inwardly, rather than canceling each other out. And for the first band, the same inward superposition rather than mutual cancellation as that of the second band also occurs with respect to the adjacent planar unit cell. Thus, when the planar unit cell is loaded, inward collapse occurs inside it, forming an aggregation effect in a local area. Therefore, this two-dimensional planar unit cell has a negative Poisson's ratio characteristic in both directions after being arranged with an adjacent planar unit cell array.

[0025] Furthermore, on the metamaterial structure, the coupling of the planar unit cell is introduced by the two unit structures connected by the first band of the planar unit cell, enabling the negative Poisson's ratio characteristic to be extended in the third dimension and enhancing the local response characteristic of the unit structure, thereby forming a three-dimensional metamaterial structure with stronger mechanical properties and vibration damping properties.

[0026] Furthermore, the two unit structures connected by the second band of the planar unit cell constrain the originally isolated unit structures, improve the stiffness of the overall structure, and also form a region with relatively concentrated mass inside the unit cell. This characteristic of mass concentration plays an important role in the process of vibration wave transmission and can trigger local resonance at a specific frequency. When the natural frequency of the local area matches the external excitation frequency, these local areas will generate a significant vibration response. However, since the coupling between these local areas and the overall structure is weak, the resonance mode of the overall structure will not be significantly affected. Therefore, the vibration energy can be effectively dissipated within the local area, thereby improving the vibration damping and isolation effects of the tire structure. Description of the Drawings

[0027] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, are used to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are included in this specification and form a part of this specification;

[0028] Figure 1 is an axonometric schematic diagram of a metamaterial structure according to an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the structure of a planar cell according to an embodiment of the present invention;

[0030] Figure 3 is a front view schematic diagram of a unit structure according to an embodiment of the present invention;

[0031] Figure 4 is a front view schematic diagram of a tire structure according to an embodiment of the present invention;

[0032] Figure 5 is the compression simulation result of a metamaterial structure according to an embodiment of the present invention;

[0033] Figure 6 is the simulation result of force-displacement of a metamaterial structure according to an embodiment of the present invention;

[0034] Figure 7 is the vibration reduction effect diagram of a metamaterial structure according to an embodiment of the present invention.

[0035] Reference numerals: 10, ligament; 11, first section; 12, second section; 201, structural square; 202, preset square; 301, first strip; 302, second strip; 300a, first planar cell; 300b, second planar cell; 300c, third planar cell. Detailed embodiments

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] In space exploration missions, space vehicles need to cope with extreme environments and complex terrains. The tires of space vehicles need to handle irregular terrains and high impact loads on the surfaces of the moon, Mars, etc. in extreme environments.

[0038] In view of the above problems, the space vehicle provided by the exemplary embodiments of the present invention has a tire structure formed by a metamaterial structure. The lightweight property and the mechanical property of negative Poisson's ratio of the metamaterial structure can be utilized to endow the tire structure of the space vehicle with good tensile expansion properties, a relatively high shear modulus and fracture toughness, as well as remarkable impact resistance, noise suppression effect and efficient vibration damping performance.

[0039] Figure 1 is an axonometric structural schematic diagram of a metamaterial structure according to an embodiment of the present invention; Figure 2 is a structural schematic diagram of a planar cell according to an embodiment of the present invention; Figure 3 is a front view structural schematic diagram of a unit structure according to an embodiment of the present invention. As Figures 1-3 shown, in the space vehicle provided by the exemplary embodiments of the present invention, the tire structure includes a metamaterial structure formed by three planar cells, namely: a first planar cell 300a parallel to the XOY plane, a second planar cell 300b parallel to the YOZ plane, and a third planar cell 300c parallel to the ZOX plane. The centers of the three planar cells coincide.

[0040] As Figure 1 shown, the second planar cell 300b and the third planar cell 300c are arranged in the vertical direction, and the first planar cell 300a is arranged in the horizontal direction. The first strip 301 at the top of the second planar cell 300b and the first strip 301 at the top of the third planar cell 300c are connected in a cross shape; the first strip 301 at the bottom of the second planar cell 300b and the first strip 301 at the bottom of the third planar cell 300c are also connected in a cross shape. The two second strips 302 of the first planar cell 300a and the two second strips 302 of the third planar cell 300c are connected in a cross shape.

[0041] As Figure 2 shown, the planar cell is composed of: four unit structures are connected in sequence, and the adjacent two second segments 12 of each unit structure are respectively connected to the second segments 12 of the adjacent two unit structures, and each unit structure is arranged in mirror symmetry with the adjacent two unit structures.

[0042] The planar cell includes two relatively outwardly convex first strips 301 and two relatively inwardly concave second strips 302; the first strip 301 and the second strip 302 are respectively formed by the ligaments 10 connected between the adjacent two unit structures.

[0043] As Figure 3As shown, the unit structure is composed of four arc-shaped ligaments 10. The four ligaments 10 are rotationally symmetrically distributed. The ligament 10 has a first section 11 close to the rotation center and a second section 12 far from the rotation center. The first sections 11 of the four ligaments 10 enclose a quadrilateral frame, and the concave sides of the four ligaments 10 face the rotation center.

[0044] Exemplarily, the connection line of the outer contour of the unit structure is a preset square 202, that is, the four sides of the preset square 202 respectively pass through the sides of the free ends of the corresponding ligaments 10.

[0045] Exemplarily, the quadrilateral frame is determined by a constructed square 201. Among them, the four vertices of the constructed square 201 pass through the center lines of the four first sections 11 of the frame. The four sides of the constructed square 201 are respectively parallel to the four sides of the preset square 202, and the centers of the two coincide.

[0046] In some embodiments, the ratio of the side length a2 of the constructed square 201 of the frame to the side length a1 of the preset square 202 is greater than zero and less than or equal to 0.5, and is optionally 0.1, 0.2, 0.25, 0.3 or 0.4.

[0047] In some embodiments, in the same unit structure, there is a preset spacing between the free end of the second section 12 and the side of the preset square 202 passed by the free end of the adjacent second section 12. The ratio of the preset spacing d1 to the side length a1 of the preset square 202 is greater than zero and less than or equal to 0.5, and is optionally 0.1, 0.2, 0.25, 0.3 or 0.4. It can be understood that the sum of the spacing between the free end of the second section 12 and the opposite side of the preset square 202 and the above preset spacing is the side length of the preset square 202.

[0048] In some embodiments, the ratio of the width w1 of the ligament 10 to the side length a1 of the preset square 202 is greater than zero and less than or equal to 0.3; the ratio of the thickness of the ligament 10 to the side length a1 of the preset square 202 is greater than zero and less than or equal to 0.3; wherein, the width w1 of the ligament 10 can be the same as the value of the thickness, that is, the cross-section of the ligament 10 can be a square.

[0049] As can be seen from the above, the metamaterial structure provided by the exemplary embodiment of the present invention can exhibit negative Poisson's ratio characteristics in at least three directions when bearing loads. Through the mutual coupling between unit structures and between planar cells, it can enhance from the local of the unit structure to the internal collapse of the planar cells and the multi-directional negative Poisson's ratio of the metamaterial structure, effectively dispersing the impact force of the irregular surface of the moon, so that the metamaterial structure has stronger mechanical and vibration damping properties.

[0050] Figure 4It is a front view structural schematic diagram of a tire structure according to an embodiment of the present invention. As Figure 4 shown, the tire structure provided by the exemplary embodiment of the present invention is obtained by bending the metamaterial structure by 22.5° in space and arranging it in a circumferential array with a target bending radius. That is, the tire structure is composed of 16 metamaterial structures per week, thus forming a complete tire support structure.

[0051] In some embodiments, the tire structure is an integrally formed part. The material of the metamaterial structure includes one of nickel-titanium shape memory alloy, copper-based shape memory alloy, and iron-based shape memory alloy.

[0052] The metamaterial structure can be integrally printed and formed by selective laser melting technology. The metal powder used is nickel-titanium shape memory alloy powder. The nickel-titanium shape memory alloy powder is selectively melted by a high-power laser to form a 2D slice of the specimen, and a 3D lattice structure of the metamaterial structure is formed by layer-by-layer printing.

[0053] During the deformation process of the metamaterial structure with negative Poisson's ratio, the voids inside the structure will change in shape and size. Shape memory alloy has superelastic properties and can maintain elasticity within a large strain range to adapt to the complex deformation of the structure. Moreover, shape memory alloy can provide additional restoring force after deformation, making the negative Poisson's ratio structure easier to return to its initial state. Therefore, the use of shape memory alloy material for the metamaterial structure significantly improves the recovery ability of the structure, reduces the permanent damage caused by the accumulation of deformation, and extends the service life of the metamaterial structure.

[0054] A specific embodiment is given below to further illustrate the vibration damping performance of the metamaterial structure of the exemplary embodiment of the present invention.

[0055] The material of the metamaterial structure is nickel-titanium shape memory alloy; the numerical simulation software Abaqus is used to verify the negative Poisson's ratio performance of the metamaterial structure.

[0056] The unit used is a solid entity unit, and the three-dimensional solid mesh type is divided into C3D10 units. The global seed size is 2mm (to ensure that each ligament has at least three layers of meshes to guarantee the accuracy of the calculation results). The parameters of nickel-titanium shape memory alloy are used, modulus E = 56000MPa, Poisson's ratio ν = 0.33, density ρ = 6.45g / cm 3 .

[0057] The geometric parameters of the metamaterial structure: a1 = 100mm, a2 = 25mm, d1 = 17mm, w1 = 10mm, and the thickness of the ligament is 10mm.

[0058] The metamaterial structure is placed between two rigid plates coupled to corresponding reference points. The bottom plate fixes six degrees of freedom, and the top plate imposes a 10% displacement constraint in the height direction of the corresponding metamaterial structure. Symmetric boundary conditions are added to the surface perpendicular to the rigid plates to extract the longitudinal and transverse strains of the metamaterial structure. The results are shown in Figure 2. Figure 5 As shown. Among them, Figure 5 is a compression simulation result of the metamaterial structure according to an embodiment of the present invention.

[0059] When a general material is subjected to longitudinal displacement, the two ends of the material expand outward, and its longitudinal strain is defined as negative and its transverse strain is defined as positive. Figure 5 It can be seen that when the metamaterial structure is subjected to a longitudinal load, the material contracts inwardly in the transverse direction, so its positive strain is negative and its transverse strain is also negative. Therefore, the metamaterial structure of the exemplary embodiment of the present invention has a negative Poisson's ratio characteristic.

[0060] The temperature of the metamaterial structure is set above the austenite transformation temperature, and a displacement load is applied to the metamaterial structure again. After the initial elastic stage, the stress induces the austenite phase to begin to transform into the martensite phase. After unloading, the martensite returns to the austenite state and elastic deformation recovery is achieved. The results are shown in Figure 2. Figure 6 shown. Figure 6 is a simulation result of the force-displacement of the metamaterial structure according to an embodiment of the present invention.

[0061] Depend on Figure 6 It can be seen that the metamaterial structure formed by shape memory alloy can recover within a certain range after exceeding the elastic limit, while general materials cannot recover after plastic deformation.

[0062] The band gap of the metamaterial structure is analyzed using the numerical simulation software Comsol. Periodic boundary conditions are applied to it to obtain the band gap diagram of the metamaterial structure, such as Figure 7 As shown. Among them, Figure 7 is a diagram showing the vibration reduction effect of the metamaterial structure according to an embodiment of the present invention.

[0063] Depend on Figure 7 It can be seen that it shows the energy band diagram in the X direction of the irreducible Brillouin zone, indicating that it can produce a band gap (band gap) that prohibits the propagation of waves.

[0064] Specifically, for the vibration propagation of the entire metamaterial structure in the X direction, the first eight characteristic frequencies of the structure are calculated, where the band gap is the portion indicated by the gray shadow, and the band gap range is 320 Hz to 375 Hz. Within this band gap range, the wave propagation of the vibration along the X direction is prohibited, indicating that the metamaterial structure can achieve a good vibration reduction effect.

[0065] Those skilled in the art should understand that the above embodiments are only for clearly illustrating the present invention, rather than limiting the scope of the present invention. For those skilled in the art, other changes or modifications can be made based on the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A space vehicle, characterized in that, It includes a tire structure, and the tire structure includes a metamaterial structure formed by three planar unit cells, and the planar unit cell includes four unit structures; The unit structure includes four arc-shaped ligaments, and the four ligaments are rotationally symmetrically distributed. The ligament has a first section close to the rotation center and a second section far from the rotation center; The first sections of the four ligaments enclose a quadrilateral frame, and the concave sides of the four ligaments face the rotation center; The four unit structures are connected in sequence. The adjacent two second sections of each unit structure are respectively connected to the second sections of the adjacent two unit structures, and each unit structure and the adjacent two unit structures are mirror-symmetrically arranged; The planar unit cell includes two relatively outwardly convex first bands and two relatively inwardly concave second bands; the first band and the second band are respectively formed by the connected ligaments of two adjacent unit structures.

2. The space vehicle according to claim 1, characterized in that, The connection line of the outer contour of the unit structure is a preset square; the ratio of the side length of the constructed square of the frame to the side length of the preset square is greater than zero and less than or equal to 0.5; Each vertex of the constructed square is located on the center line of the corresponding first section of the frame.

3. The space vehicle according to claim 2, characterized in that, In the same unit structure, there is a preset distance between the free end of the second section and the side of the preset square passed by the free end of the adjacent second section, and the ratio of the preset distance to the side length of the preset square is greater than zero and less than or equal to 0.

5.

4. The space vehicle according to claim 2, characterized in that, The ratio of the width of the ligament to the side length of the preset square is greater than zero and less than or equal to 0.

3.

5. The space vehicle according to claim 4, characterized in that, The ratio of the thickness of the ligament to the side length of the preset square is greater than zero and less than or equal to 0.

3.

6. The space vehicle according to any one of claims 1-5, characterized in that, The tire structure is obtained by spatially bending the metamaterial structure by 22.5° and arranging it in a circular array with a target bending radius.

7. The space vehicle according to claim 6, characterized in that, The tire structure is a one-piece molding.

8. The space vehicle according to claim 6, characterized in that, The material of the metamaterial structure includes one of nickel-titanium shape memory alloy, copper-based shape memory alloy, and iron-based shape memory alloy.

9. The space vehicle according to claim 6, characterized in that, The bandgap value range of the bandgap of the metamaterial structure is 320 Hz to 375 Hz.

10. The space vehicle according to claim 6, characterized in that, The width and thickness values of the ligament are the same.

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