A buffer and energy absorption device based on 4D printing multifunctional pixel mechanical metamaterials

Abstract

The present invention provides a buffering and energy absorption device based on a 4D printing multifunctional pixel mechanical metamaterial, which relates to the technical field of metamaterials. The device includes a frame structure and a mechanical pixel structure. The mechanical pixel structure is modularly designed and includes a bistable module for generating bistable deformation and a compressive-torsional coupling module for generating compressive-torsional coupling deformation. The modules generating these two types of deformations are directly connected or connected through a connection module between a top cover module and a base module to form a mechanical pixel structure. Multiple mechanical pixel structures are independently installed in the frame structure. Similar to adjusting the image by adjusting the color of pixel points on a display, the present invention can adjust the macroscopic buffering or vibration damping performance of the device by adjusting the configuration of the mechanical pixel structure, realizing the reconfigurability of the mechanical metamaterial. Moreover, when a certain mechanical pixel structure in the device is damaged, the modular design is also beneficial to the repair of a single mechanical pixel structure.

Description

Technical Field

[0001] The present invention relates to the technical field of metamaterials, and more particularly, to a buffer and energy absorption device based on 4D printed multi-functional pixel mechanical metamaterials. Background Art

[0002] Precision instruments usually require vibration isolation and energy absorption devices such as gaskets to protect them during transportation and operation. Traditional vibration isolation gaskets and other devices have a relatively single structural form, weak damping adjustment performance of the structure, lack of reconfigurability and adaptability, and are difficult to meet the vibration isolation requirements of precision instruments.

[0003] Mechanical metamaterials are complex artificial materials composed of periodically arranged microstructures. By adjusting the geometric parameters of the microstructures, their macroscopic mechanical properties can be adjusted, and they have potential application prospects in aerospace, vibration damping and energy absorption, etc. Mechanical metamaterials provide an opportunity for designing new vibration isolation and energy absorption devices. However, the vibration isolation characteristics of existing mechanical metamaterials originate from the geometric parameters of the microstructures, and the configuration and mechanical properties of the metamaterials are usually fixed and unchangeable after preparation, which is not conducive to adjusting the buffer and vibration damping performance. Summary of the Invention

[0004] The problem to be solved by the present invention is that the vibration isolation characteristics of existing mechanical metamaterials originate from the geometric parameters of the microstructures, and the configuration and mechanical properties of the metamaterials are usually fixed and unchangeable after preparation, which is not conducive to adjusting the buffer and vibration damping performance.

[0005] To solve the above problems, the present invention provides a buffer and energy absorption device based on 4D printed multi-functional pixel mechanical metamaterials, including: a frame structure and a plurality of mechanical pixel structures, and the plurality of mechanical pixel structures are independently arranged in the frame structure; the mechanical pixel structure includes a top cover module, at least one bistable module, at least one compression-torsion coupling module, at least one force threshold switch module and a base module, or the mechanical pixel structure includes a top cover module, at least one bistable module, at least one compression-torsion coupling module, at least one force threshold switch module, a base module and a connection module; at least one of the bistable modules and at least one of the compression-torsion coupling modules are connected between the top cover module and the base module; each module of the mechanical pixel structure is directly connected or connected through the connection module, wherein the materials used for each module of the mechanical pixel structure have shape memory characteristics, the bistable module is used to generate bistable deformation, and the compression-torsion coupling module is used to generate compression-torsion coupling deformation; the number of the force threshold switch modules is equal to the number of the compression-torsion coupling modules, and the force threshold switch modules are installed in the compression-torsion coupling modules to control the opening or closing of the torsion deformation of the compression-torsion coupling modules.

[0006] Preferably, the compression-torsion coupling module includes a first node, a second node, a ligament, a plug, and a rotation stopper. The first node and the second node are oppositely arranged. The ligament is connected between the first node and the second node, and the connection of the ligament to the first node and the second node includes a right-handed connection mode and a left-handed connection mode. The plug is arranged on the first node, and the rotation stopper is arranged on the second node. The plug is used to be inserted into the rotation stopper.

[0007] Preferably, the rotation stopper includes a base, the base is arranged on the second node, a groove structure is formed on the top surface of the base, and a first protrusion is arranged at one end of the plug close to the rotation stopper. The first protrusion is used to be inserted into the groove structure.

[0008] Preferably, the groove structure includes a first groove and a plurality of second grooves. The first groove is arranged at the center of the top surface of the base, and the first groove is coaxially arranged with the plug. The plurality of second grooves are radially distributed along the circumference of the first groove, and the plurality of second grooves communicate with the first groove. The number of the first protrusions is less than or equal to the number of the second grooves, and the plurality of first protrusions are simultaneously inserted into the second grooves.

[0009] Preferably, an installation groove is arranged on the second node, and the installation groove is used to install the force threshold switch module. The force threshold switch module includes a housing, the interior of the housing is hollow, and one end of the housing is open and the other end is provided with a through hole. The housing covers the outside of the rotation stopper, and the housing is coaxially arranged with the rotation stopper and the plug. A second protrusion is arranged on the outer wall of the plug, and the second protrusion can be extruded through the through hole.

[0010] Preferably, each module of the mechanical pixel structure is connected by a quick-release pin structure, a mortise and tenon structure, gluing or integral molding.

[0011] Preferably, the bistable module is composed of twelve curved beams. The twelve curved beams form a "field" - shaped structure. The "field" - shaped structure has two stable states, and the two stable states are used to be converted under the action of a load.

[0012] Preferably, bistable connection columns are provided at the midpoints of the four sides, the center point, and the four vertices of the "field" - shaped structure. The bistable connection columns at the midpoints of the four sides of the "field" - shaped structure and the bistable connection columns at the center point and the four vertices of the "field" - shaped structure are respectively located on two opposite faces of the "field" - shaped structure. A press - torsion connection groove structure is provided on the first node and the second node of the press - torsion coupling module, a top - cover connection groove structure is provided at the bottom of the top - cover module, and a base - seat connection groove structure is provided at the top of the base - seat module. The bistable connection columns are used for mating connection with the press - torsion connection groove structure, the top - cover connection groove structure, or the base - seat connection groove structure.

[0013] Preferably, the connection module includes a bistable connection module. Two adjacent bistable modules are connected by the bistable connection module. The bistable connection module includes a first substrate and a first connection groove structure. The first connection groove structure is provided at the center point, the four vertices, and the midpoints of the four sides of the first substrate. The first connection groove structures at the center point and the four vertices of the first substrate and the first connection groove structures at the midpoints of the four sides of the first substrate are respectively located on two opposite faces of the first substrate. The first connection groove structure is used for mating connection with the bistable connection columns.

[0014] Preferably, the connection module further includes a press - torsion connection module. Two adjacent press - torsion coupling modules are connected by the press - torsion connection module. The press - torsion coupling module and the top - cover module or the base - seat module are connected by the press - torsion connection module. The press - torsion connection module includes a second substrate and second connection columns. The second connection columns are provided at the center point, the four vertices, and the midpoints of the four sides of the second substrate. The second connection columns at the center point and the four vertices of the second substrate and the second connection columns at the midpoints of the four sides of the second substrate are respectively located on two opposite faces of the second substrate. The second connection columns are used for mating connection with the press - torsion connection groove structure, the first connection groove structure, the top - cover connection groove structure, or the base - seat connection groove structure.

[0015] The advantages of the present invention over the prior art are as follows: The device of the present invention includes a frame structure and a mechanical pixel structure. The mechanical pixel structure is modularly designed and includes a bistable module for generating bistable deformation and a compressive-torsional coupling module for generating compressive-torsional coupling deformation. The modules generating these two types of deformations are directly connected or connected through a connection module between the top cover module and the base module to form an independent mechanical pixel structure. Multiple mechanical pixel structures are independently installed within the frame structure. Similar to a display that adjusts the image by adjusting the color of pixel points, the present invention can adjust the macroscopic buffering or vibration damping performance of the device by adjusting the configuration of the mechanical pixel structure. Moreover, when a certain mechanical pixel structure in the device is damaged, the modular design also facilitates the repair of a single mechanical pixel structure. Each module of the mechanical pixel structure of the present invention is made of a material with shape memory characteristics, and the configuration and mechanical properties of each module can be changed through the shape memory function of the material to obtain a device with different configurations and mechanical properties, realizing the reconfigurability of the mechanical metamaterial to meet, for example, the vibration isolation requirements of precision instruments. The present invention also installs a force threshold switch module within the compressive-torsional coupling module to control the opening or closing of the torsional deformation of the compressive-torsional coupling module, thereby controlling the configuration generated by the device of the present invention and realizing the deformation characteristics of different mechanical pixel structures under different configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the overall structure of the device in an embodiment of the present invention;

[0017] Figure 2 Schematic diagram of the frame structure in an embodiment of the present invention;

[0018] Figure 3 Schematic diagram of a single mechanical pixel structure in an embodiment of the present invention;

[0019] Figure 4 Front view of a buffering and energy absorption device based on 4D printed multifunctional pixel mechanical metamaterial;

[0020] Figure 5 is Figure 1 Top view of the device in ;

[0021] Figure 6 Front view of the mechanical pixel structure;

[0022] Figure 7 is Figure 1 Explosion schematic diagram of the device in ;

[0023] Figure 8 Front view of each module of the device;

[0024] Figure 9 Schematic diagram of the first stable state of the bistable module;

[0025] Figure 10 Schematic diagram of the second stable state of the bistable module;

[0026] Figure 11 Schematic diagram of the press-twist coupling module with a right-handed connection pattern;

[0027] Figure 12 Front view of the press-twist coupling module with a right-handed connection pattern;

[0028] Figure 13 Schematic diagram of the press-twist coupling module with a left-handed connection pattern;

[0029] Figure 14 Front view of the press-twist coupling module with a left-handed connection pattern;

[0030] Figure 15 Schematic diagram of the ON state of the press-twist and force threshold switch combination module;

[0031] Figure 16 Another perspective schematic diagram of the ON state of the press-twist and force threshold switch combination module;

[0032] Figure 17 Front view of the ON state of the press-twist and force threshold switch combination module;

[0033] Figure 18 Schematic diagram of the OFF state of the press-twist and force threshold switch combination module;

[0034] Figure 19 Another perspective schematic diagram of the OFF state of the press-twist and force threshold switch combination module;

[0035] Figure 20 Front view of the OFF state of the press-twist and force threshold switch combination module;

[0036] Figure 21 Partial schematic diagram of the plug cooperating with the rotary stopper;

[0037] Figure 22 Configuration diagram of the deformation of the mechanical pixel structure in Example 1;

[0038] Figure 23 Configuration diagram of the programmed mechanical pixel structure after programming 1 module in Example 1;

[0039] Figure 24 Configuration diagram of the programmed mechanical pixel structure after programming 2 modules in Example 1;

[0040] Figure 25 Configuration diagram of the programmed mechanical pixel structure after programming 3 modules in Example 1;

[0041] Figure 26 It is the configuration diagram after programming 4 modules in the mechanical pixel structure in Embodiment 1;

[0042] Figure 27 It is the configuration diagram after programming 5 modules in the mechanical pixel structure in Embodiment 1;

[0043] Figure 28 It is the structural schematic diagram of the tension stop plate;

[0044] Figure 29 It is the structural schematic diagram of the tension stop rod;

[0045] Figure 30 It is another structural schematic diagram of the frame structure;

[0046] Figure 31 It is the structural schematic diagram of the device in Embodiment 2;

[0047] Figure 32 It is the structural schematic diagram of the bistable connection module;

[0048] Figure 33 It is the structural schematic diagram of the compression-torsion connection module;

[0049] Figure 34 It is the exploded view of the device in Embodiment 2.

[0050] Explanation of reference numerals: 1. Frame structure; 2. Mechanical pixel structure; 3. Top cover module; 4. First bistable module; 5. First compression-torsion coupling module; 6. Second bistable module; 7. Second compression-torsion coupling module; 8. Third bistable module; 9. Base module; 10. First force threshold switch module; 11. Second force threshold switch module; 12. Compression-torsion connection module; 13. Rotation stopper; 14. Installation groove; 15. Plug; 16. Ligament; 17. First node; 18. Second node; 19. Bistable connection module; 101. Frame body; 102. Tension stop plate; 103. Tension stop rod; 41. Curved beam; 42. Bistable connection column; 1901. First substrate; 1902. First connection groove structure; 1201. Second substrate; 1202. Second connection column. Detailed implementation manners

[0051] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0052] A buffering and energy-absorbing device based on a 4D printing multifunctional pixel mechanical metamaterial in an embodiment of the present invention (hereinafter simply referred to as the device) includes: a frame structure 1 and a plurality of mechanical pixel structures 2, and the plurality of mechanical pixel structures 2 are independently arranged in the frame structure 1; the mechanical pixel structure 2 includes a top cover module 3, at least one bistable module, at least one compression-torsion coupling module, at least one force threshold switch module, and a base module 9, or the mechanical pixel structure 2 includes a top cover module 3, at least one bistable module, at least one compression-torsion coupling module, at least one force threshold switch module, a base module 9, and a connection module; at least one of the bistable modules and at least one of the compression-torsion coupling modules are connected to each other between the top cover module 3 and the base module 9; each module of the mechanical pixel structure 2 is directly connected or connected through the connection module, wherein the materials used for each module of the mechanical pixel structure 2 have shape memory characteristics, the bistable module is used to generate bistable deformation, and the compression-torsion coupling module is used to generate compression-torsion coupling deformation; the number of the force threshold switch modules is equal to the number of the compression-torsion coupling modules, and the force threshold switch modules are installed in the compression-torsion coupling modules to control the opening or closing of the torsional deformation of the compression-torsion coupling modules.

[0053] In this embodiment, the device is composed of a plurality of mechanical pixel structures 2 and a frame structure 1. The plurality of mechanical pixel structures 2 are not connected to each other and are independently arranged in the frame structure 1. For example, the plurality of mechanical pixel structures 2 are arranged in an array in the frame structure 1, or alternatively, according to the size of the precision instrument to be protected, the number and size of the mechanical pixel structures 2 can be changed and designed in other forms of arrangement. In this embodiment, the mechanical pixel structure 2 is modularly designed. Similar to a display adjusting an image by adjusting the color of pixel points, the macroscopic buffering or vibration damping performance of the device can be adjusted by adjusting the configuration of the mechanical pixel structure 2. And when a certain mechanical pixel structure 2 in the device is damaged, the modular design is also beneficial to the repair of a single mechanical pixel structure 2. In this embodiment, each module of the mechanical pixel structure 2 is made of a material with shape memory characteristics. For example, shape memory polymers or shape memory polymer composites. Shape memory polymers are a kind of intelligent materials, which have the ability to maintain a temporary shape and return to their initial shape under external excitation. Therefore, through the shape memory function of the material, the configuration and mechanical properties of each module can be changed, and a device with different configurations and mechanical properties can be obtained, realizing the reconfigurability of the mechanical metamaterial to meet, for example, the vibration isolation requirements of precision instruments.

[0054] In this embodiment, the mechanical pixel structure 2 includes a top cover module 3 and a base module 9. At least one bistable module, at least one compression-torsion coupling module, and at least one force threshold switch module are connected between the top cover module 3 and the base module 9. The modules are directly connected through the connection structure on the module, or indirectly connected through the connection module. A mechanical pixel structure 2 is formed by the above modules, and multiple mechanical pixel structures 2 are respectively arranged in the frame structure 1 to obtain the device. For example, Figure 3 , Figure 7 As shown, the mechanical pixel structure 2 is composed of a base module 9, three bistable modules, two compression-torsion coupling modules, two force threshold switch modules and a top cover module 3. For the convenience of description, the three bistable modules are respectively recorded as the first bistable module 4, the second bistable module 6, and the third bistable module 8, the two compression-torsion coupling modules are respectively recorded as the first compression-torsion coupling module 5 and the second compression-torsion coupling module 7, and the two force threshold switch modules are respectively recorded as the first force threshold switch module 10 and the second force threshold switch module 11. In the mechanical pixel structure 2, the top cover module 3 is connected to the upper part of the first bistable module 4, the lower part of the first bistable module 4 is connected to the upper end of the first compression-torsion coupling module 5, the lower end of the first compression-torsion coupling module 5 is connected to the upper part of the second bistable module 6, the lower part of the second bistable module 6 is connected to the upper end of the second compression-torsion coupling module 7, the lower end of the second compression-torsion coupling module 7 is connected to the upper part of the third bistable module 8, and the lower part of the third bistable module 8 is connected to the upper end of the base module 9.

[0055] In this example, the connection between the modules of the mechanical pixel structure 2 is in the form of a column and a groove, and a connecting column is set on the bistable module, and a connecting groove is set on the compression-torsion coupling module, the top cover module 3 and the base module 9, and the three bistable modules are alternately connected with the two compression-torsion coupling modules, and the top cover module 3 and the base module 9 are both connected to the bistable module. Therefore, it does not involve the connection of modules with the same connection structure. For example, the connection between two bistable modules has a column as the connection structure and cannot be directly connected, or the connection between two compression-torsion coupling modules has a groove as the connection structure and cannot be directly connected, or the connection between the compression-torsion coupling module and the top cover module 3 has a groove as the connection structure and cannot be directly connected, or the connection between the compression-torsion coupling module and the base module 9 has a groove as the connection structure and cannot be directly connected. Therefore, the mechanical pixel structure 2 described in this example may not include a connection module, and the connection structure on each module is matched through a suitable connection sequence, thereby realizing the connection between each module. Of course, in other examples, if the number of bistable modules or compression-torsion coupling modules is increased, or the connection sequence of the bistable modules and the compression-torsion coupling modules is changed, for example Figure 31The shown mechanical pixel structure 2 is still composed of 1 base module 9, 3 bistable modules, 2 pressure-torsion coupling modules, 2 force threshold switch modules and 1 top cover module 3. However, the connection order of each module is different from the above example. In this example, two bistable modules are connected to each other, and two pressure-torsion coupling modules are connected to each other. There are two identical structures connected, so a connection module is needed for connection. Therefore, for the case where the connection structures on two modules do not match, the mechanical pixel structure 2 includes a connection module for connecting between two modules with the same connection structure. The specific connection method of each module in this example can be found in Embodiment 2 below.

[0056] In some of these embodiments, as Figures 12 to 14 shown, the pressure-torsion coupling module includes a first node 17, a second node 18, a ligament 16, a plug 15 and a rotation stopper 13. The first node 17 and the second node 18 are arranged oppositely. The ligament 16 is connected between the first node 17 and the second node 18. And the connection of the ligament 16 to the first node 17 and the second node 18 includes a right-handed connection mode and a left-handed connection mode. The plug 15 is arranged on the first node 17, and the rotation stopper 13 is arranged on the second node 18. The plug 15 is used to be inserted into the rotation stopper 13.

[0057] In this embodiment, the pressure-torsion coupling module is composed of two oppositely arranged nodes, namely the first node 17 and the second node 18, which form the top and bottom of the module. A ligament 16 is connected between the two nodes. And the connection of the ligament 16 to the two nodes is divided into a right-handed connection mode and a left-handed connection mode. Chirality, also known as handedness, is divided into left-handed and right-handed. Taking a helix as an example, when defining its chirality, the right thumb can be pointed in the axial direction of the helix, and the other four fingers are clenched into a fist, and then the advancing direction of the rotation of the helix is compared accordingly. If the helix is in the direction tending from the root of the finger to the tip of the thumb along the four fingers, then the helix is called right-handed; otherwise, it is called left-handed. As Figure 12 、 Figure 14 shown, 4 spiral ligaments are adopted between the two nodes. Of course, in other embodiments, linear ligaments can also be adopted. The pressure-torsion coupling module with a left-handed connection mode between the ligament 16 and the two nodes is as Figure 13 、 Figure 14 shown. The pressure-torsion coupling module with a right-handed connection mode between the ligament 16 and the two nodes is as Figure 11 、 Figure 12As shown. Adopting this chiral connection mode causes the compression-torsion coupling module to generate torsional deformation under axial deformation. In addition, a plug 15 and a rotation stopper 13 are respectively provided on the two nodes. Thus, when the device is subjected to an external load, the compression-torsion coupling module will undergo torsional deformation, that is, a relative rotational deformation will occur between the two nodes. Since the plug 15 is provided on the first node 17 and the rotation stopper 13 is provided on the second node 18, the plug 15 and the rotation stopper 13 also undergo relative rotation, which may include three cases, namely, the first node 17 drives the plug 15 to rotate, the second node 18 drives the rotation stopper 13 to rotate, and the plug 15 and the rotation stopper 13 rotate simultaneously. Since the rotation of the two nodes is relative, the rotation of the plug 15 and the rotation stopper 13 is also relative. Taking the external load on the device as a pressure load as an example, when the first node 17 is compressed, the plug 15 is inserted into the rotation stopper 13. At this time, when further compressed, the compression-torsion coupling module no longer undergoes mutual torsional deformation due to the limitation of the plug 15 and the rotation stopper 13, thereby realizing the control of the torsional deformation of the compression-torsion coupling module. Of course, if the external load on the device is a tensile load, when the plug 15 is pulled out of the rotation stopper 13, the restriction on the torsional deformation of the compression-torsion coupling module is released, enabling the compression-torsion coupling module to undergo torsional deformation.

[0058] In some of the embodiments, the rotation stopper 13 includes a base, the base is provided on the second node 18, a groove structure is provided on the top surface of the base, and a first protrusion is provided at one end of the plug 15 close to the rotation stopper 13, and the first protrusion is used to insert into the groove structure.

[0059] In this embodiment, a first protrusion is provided at the end of the plug 15, and a groove structure is provided on the rotation stopper 13. Through the insertion of the first protrusion and the groove structure, the connection between the plug 15 and the rotation stopper 13 is realized. By connecting or disconnecting the plug 15 and the rotation stopper 13, it is possible to control whether the compression-torsion coupling module can undergo torsional deformation under an external load.

[0060] In some of the embodiments, the groove structure includes a first groove and a plurality of second grooves. The first groove is provided at the center of the top surface of the base, and the first groove is coaxially arranged with the plug 15. The plurality of second grooves are radially distributed along the circumference of the first groove, and the plurality of second grooves communicate with the first groove. The number of the first protrusions is less than or equal to the number of the second grooves, and the plurality of first protrusions are simultaneously inserted into the second grooves.

[0061] In this embodiment, a first groove coaxial with the plug 15 is provided on the base of the rotary stopper 13 for the insertion of the plug 15. At the same time, since a first protrusion is provided at the end of the plug 15, a second groove for mating connection with the first protrusion is also provided. The second grooves are distributed circumferentially along the first groove. Thus, when the press-torsion coupling module undergoes torsional deformation during compression, the first node 17 and the second node 18 rotate relative to each other. For the convenience of description, taking the first node 17 rotating and the second node 18 remaining stationary as an example, at this time, the first node 17 drives the plug 15 to rotate. When compressed until the lower part of the plug 15 contacts the top surface of the base of the rotary stopper 13, the first protrusion on the plug 15 slides on the top surface of the base. When the first protrusion slides into the second groove, the first protrusion and the second groove engage with each other, realizing the plug-in fixation of the plug 15 in the rotary stopper 13. Therefore, when the press-torsion coupling module is further compressed and deformed, due to the mutual engagement of the first protrusion and the second groove, the press-torsion coupling module will not produce torsional deformation either, realizing the closing of the torsional deformation of the press-torsion coupling module.

[0062] In this embodiment, the number of the first protrusions is less than or equal to the number of the second grooves. Thus, through the mating connection of multiple first protrusions and second grooves, the connection between the plug 15 and the rotary stopper 13 is realized, and the connection strength is increased, ensuring the safe and effective closing of the torsional deformation of the press-torsion coupling module.

[0063] In some of the embodiments, an installation groove 14 is provided on the second node 18. The installation groove 14 is used for installing the force threshold switch module. The force threshold switch module includes a housing. The interior of the housing is hollow, and one end of the housing is open and the other end is provided with a through hole. The housing covers the outside of the rotary stopper 13, and the housing is coaxially arranged with the rotary stopper 13 and the plug 15. A second protrusion is provided on the outer wall of the plug 15, and the second protrusion can be extruded through the through hole.

[0064] In this embodiment, the state of the press-twist coupling module is further locked by the cooperation of the force threshold switch module and the second protrusion on the plug 15. For example, when the press-twist coupling module is subjected to a pressure load, the plug 15 is inserted into the rotary stopper 13. To prevent the plug 15 from rebounding after the external load is removed, causing the press-twist coupling module not to remain in the locked state, a force threshold switch module is installed on the second node 18 in this embodiment. This module is a hollow shell with an open end at one end, such that the insertion of the plug 15 into the rotary stopper 13 occurs inside the shell. By providing a second protrusion on the plug 15 and making the second protrusion pass through the through-hole in the shell only by extrusion, it can be understood that the second protrusion needs to be extruded through the through-hole under a certain external load. After the load is removed, the second protrusion that has passed through the through-hole cannot pass through the through-hole and return. Therefore, the plug 15 can be prevented from rebounding by the limitation of the second protrusion. When the press-twist coupling module is subjected to a tensile load, similar to the pressure load, the plug 15 can be prevented from rebounding by the limitation of the second protrusion. Therefore, there are two states in the cooperation between the force threshold switch module and the press-twist coupling module in this embodiment, namely the "ON" state and the "OFF" state. After the mechanical pixel structure 2 is fabricated, the plug 15 is located on the upper surface of the force threshold switch module, and it is in the "ON" state at this time. In this state, the mechanical pixel structure 2 will undergo torsional deformation under an external axial load. When an external load is applied, the plug 15 is extruded from the through-hole of the force threshold switch module and inserted into the rotary stopper 13. At this time, it is in the "OFF" state, and in this state, the mechanical pixel structure 2 will not undergo torsional deformation under an external load.Specifically, the specific processes of applying pressure load and tensile load are described as follows: When the press-twist coupling module is subjected to a pressure load and the external compression load reaches the activation force threshold of the force threshold switch module, the so-called activation force threshold of the force threshold switch module refers to the load intensity that enables the second protrusion on the plug 15 to pass through the through-hole on the force threshold switch module. At this time, the plug 15 is extruded from the through-hole of the force threshold switch module. For example, the second protrusion on the plug 15 is extruded through the through-hole from the outside of the housing and enters the inner cavity of the housing. The plug 15 continues to be inserted into the rotation stopper 13. During the process of inserting the plug 15 into the rotation stopper 13, the force threshold switch module does not restrict the deformation of the press-twist coupling module; after the plug 15 is inserted into the rotation stopper 13, the external compression load is removed, and the second protrusion on the plug 15 abuts against the inner wall of the housing and cannot pass through the through-hole, thereby inhibiting the rebound of the plug 15 and keeping the force threshold switch module in the "OFF" state. At this time, the rotation stopper 13 cooperates with the first protrusion on the plug 15, which will restrict the press-twist coupling module from generating torsional deformation; when a tensile load is applied to the switch in the "OFF" state and reaches the activation force threshold of the force threshold switch module, the plug 15 can be pulled out from the force threshold switch module, that is, the second protrusion on the plug 15 can be extruded through the through-hole on the force threshold switch module, thereby switching the switch to the "ON" state.

[0065] In some of the embodiments, the modules of the mechanical pixel structure 2 are connected by a quick-release pin structure, a mortise and tenon structure, adhesives, or integral molding. Among them, the method of connecting the modules by a quick-release pin structure or a mortise and tenon structure facilitates the replacement of individual modules. For the mechanical pixel structure 2 in which the modules are fixedly connected by integral molding or adhesives, etc., the overall strength performance is relatively excellent, and the risk of unstable connection between the modules or falling off and misalignment during the deformation process is relatively low. In addition, in this embodiment, the number, parameters, and geometric configurations of the bistable module, the press-twist coupling module, and the force threshold switch module of the mechanical pixel structure 2 can be adjusted according to actual usage requirements. Determine the required number, parameters, and configurations of the modules according to the requirements, and then assemble the modules in a detachable or fixed manner to obtain each mechanical pixel structure 2, and then assemble multiple mechanical pixel structures 2 onto the frame structure 1 to obtain the device.

[0066] In some of the embodiments, such as Figure 9 , Figure 10As shown, the bistable module is composed of twelve curved beams 41. The twelve curved beams 41 form a "field" - shaped structure. The "field" - shaped structure has two stable states, and the two stable states are used for conversion under the action of load. The bistable module of this embodiment has bistable deformation characteristics under the action of external force. The two stable states are the first stable state and the second stable state respectively. Under the action of external load, it can be converted between the first stable state and the second stable state and can be maintained in the second stable state. The bistable module is composed of 12 curved beams 41. By adjusting the geometric parameters of the beams, the mechanical properties and stable configurations of the beams can be adjusted.

[0067] In some embodiments, such as Figure 9 、 Figure 10 As shown, bistable connecting columns 42 are arranged at the mid - points of the four sides, the center point, and the four vertices of the "field" - shaped structure. And the bistable connecting columns 42 at the mid - points of the four sides of the "field" - shaped structure and the bistable connecting columns 42 at the center point and the four vertices of the "field" - shaped structure are respectively located on two opposite faces of the "field" - shaped structure. A press - torsion connection groove structure is arranged on the first node 17 and the second node 18 of the press - torsion coupling module. A top - cover connection groove structure is arranged at the bottom of the top - cover module 3. A base connection groove structure is arranged at the top of the base module 9. The bistable connecting column 42 is used for mating connection with the press - torsion connection groove structure, the top - cover connection groove structure or the base connection groove structure.

[0068] In this embodiment, bistable connecting columns 42 are arranged on the bistable module, and a press - torsion connection groove structure is arranged on the press - torsion coupling module. Through the cooperation of the bistable connecting column 42 and the press - torsion connection groove structure, the connection between the bistable module and the press - torsion coupling module can be realized. In addition, a top - cover connection groove structure and a base connection groove structure are respectively arranged on the top - cover module 3 and the base module 9. Thus, through the cooperation of the bistable connecting column 42 and the top - cover connection groove structure and the cooperation of the bistable connecting column 42 and the base connection groove structure, the connection between the bistable module and the top - cover module 3 and the base module 9 is realized.

[0069] In this embodiment, the 12 curved beams 41 of the bistable module form a "field" - shaped structure. By adjusting the parameters of the curved beam 41, the bistable module has two configurations or stable states. Taking the first stable state as an example, the bistable module has upper and lower surfaces. Bistable connecting columns 42 are arranged at the mid - points of the four middle lines on the upper surface, and bistable connecting columns 42 are also arranged at the four vertices and the center point on the lower surface. Thus, the bistable connecting column 42 can be used to connect with other modules.

[0070] In some embodiments, such as Figure 31As shown, the connection module includes a bistable connection module 19. Two adjacent bistable modules are connected by the bistable connection module 19. As Figure 32 shown, the bistable connection module 19 includes a first substrate 1901 and a first connection groove structure 1902. The first connection groove structure 1902 is arranged at the center point, four vertices, and the midpoints of the four sides of the first substrate 1901. The first connection groove structures 1902 at the center point and four vertices of the first substrate 1901 and the first connection groove structures 1902 at the midpoints of the four sides of the first substrate 1901 are respectively located on two opposite surfaces of the first substrate 1901. The first connection groove structure 1902 is used to cooperate with the bistable connection post 42 for connection.

[0071] In this embodiment, since bistable connection posts 42 are arranged on both the upper and lower surfaces of the bistable module, and two bistable modules cannot be connected by two connection posts, it is necessary to design a bistable connection module 19 with a groove structure to connect the two bistable modules. As Figure 32 shown, the bistable connection module 19 includes a first substrate 1901. First connection groove structures 1902 are arranged on both the upper and lower surfaces of the first substrate 1901, but the arrangement positions of the first connection groove structures 1902 on the two surfaces are different, mainly for cooperating with the bistable connection posts 42 on the bistable module for connection.

[0072] In some embodiments, as Figure 31 、 Figure 34 shown, the connection module further includes a press-twist connection module 12. Two adjacent press-twist coupling modules are connected by the press-twist connection module 12. The press-twist coupling module is connected to the top cover module 3 or the base module 9 through the press-twist connection module 12. As Figure 33 shown, the press-twist connection module 12 includes a second substrate 1201 and a second connection post 1202. The second connection post 1202 is arranged at the center point, four vertices, and the midpoints of the four sides of the second substrate. The second connection posts 1202 at the center point and four vertices of the second substrate 1201 and the second connection posts 1202 at the midpoints of the four sides of the second substrate 1201 are respectively located on two opposite surfaces of the second substrate 1201. The second connection post 1202 is used to cooperate with the press-twist connection groove structure, the first connection groove structure 1902, the top cover connection groove structure, or the base connection groove structure for connection.

[0073] In this embodiment, since the upper and lower surfaces of the compression-torsion coupling module are both provided with compression-torsion connection groove structures, and the two compression-torsion coupling modules cannot be connected through the two connection grooves, it is necessary to design a compression-torsion connection module 12 with a column structure to connect the two compression-torsion coupling modules. As Figure 33 shown, the compression-torsion connection module 12 includes a second substrate 1201, and second connection columns 1202 are provided on both the upper and lower surfaces of the second substrate 1201. Only the arrangement positions of the second connection columns 1202 on the two surfaces are different, mainly for mating connection with the compression-torsion connection groove structure on the compression-torsion coupling module, or with the top cover connection groove structure on the top cover module 3, or with the base connection groove structure on the base module 9.

[0074] In some embodiments, such as Figures 28 - 30 shown, the frame structure 1 is used to fix all the mechanical pixel structures 2. This embodiment provides two forms of the frame structure 1. In one example, as Figure 28 、 Figure 2 shown, the frame structure 1 includes a frame body 101 and a tension stop plate 102, and the tension stop plate 102 is arranged inside the frame body 101. Among them, the frame body 101 is a frame structure composed of multiple rods or beams and has a certain height, which is used to support the mechanical pixel structure 2 to prevent the mechanical pixel structure 2 from tipping over. The tension stop plate 102 includes a border and multiple rib plates connected to the inner wall of the border, and the multiple rib plates are arranged vertically and horizontally. During installation, first place the base modules 9 of each mechanical pixel structure 2 inside the frame body 101. For example, Figure 1 the mechanical pixel structure 2 shown in is arranged in a nine-square grid form. Place three rows horizontally and three columns vertically of base modules 9 inside the frame body 101, and then lay the tension stop plate 102 on the nine base modules 9. The gaps formed by the vertical and horizontal arrangement of the multiple rib plates on the tension stop plate 102 are used to make way for the base connection groove structure on the base module 9. Installation holes are provided on the border of the tension stop plate 102, and holes corresponding to the installation holes are provided on the frame body 101, which are used to install the tension stop plate 102 on the frame body 101 through fasteners such as screws and bolts. Then connect other modules in sequence, for example, connect the bistable module to the base module 9. Thus, the base module 9 is restricted inside the frame body 101 by the tension stop plate 102. Since other modules are all installed on the base module 9 in sequence, each mechanical module is respectively fixed inside the frame structure 1.

[0075] In another example, such as Figure 29 and Figure 30As shown, the frame structure 1 includes a frame body 101 and a stop tie rod 103. The stop tie rod 103 is arranged inside the frame body 101. The frame body 101 in this example is the same as the aforementioned structure, and is a frame structure composed of rods, beams, etc. The difference from the previous example is that the stop tie rod 103 is a separate rod, and holes for installing with the frame body 101 are provided at both ends of the stop tie rod 103. In this example, the form of the stop tie rod 103 is adopted. Compared with the stop tie rod 103, since it is a separate rod, the installation is more flexible. The base modules 9 of each mechanical pixel structure 2 can be first placed inside the frame body 101, and then the stop tie rod 103 can be installed. Or some of the base modules 9 of the mechanical pixel structure 2 can be placed first, for example, one column of the base modules 9 can be placed first, and then after all the mechanical pixel structures 2 in this column are installed, the mechanical pixel structures 2 in other columns can be installed.

[0076] In some of these embodiments, each module of the mechanical pixel structure 2 is prepared and formed by injection molding, 3D printing, or 4D printing technology. The materials used are not limited to polymer materials such as rubber, polylactic acid, polyurethane, and thermoplastic elastomer. Of course, the polymer materials mentioned above can also be composite materials, such as materials added with carbon fiber, nanoparticles, carbon nanotube grafted carbon fiber, and short cut fiber. By using 3D printing technology to prepare intelligent materials such as shape memory polymers, the printed structure prepared can change its configuration, function, and performance over time under the excitation of the external environment. This printing technology is called 4D printing.

[0077] In some of these preferred embodiments, each module of the mechanical pixel structure 2 is made of a material with shape memory characteristics and is formed by 4D printing. The materials used in 4D printing technology can be shape memory polymers or shape memory polymer composites with shape memory characteristics. By combining 4D printing technology with mechanical metamaterials, the configuration and mechanical properties of the prepared mechanical metamaterials can change under the excitation of the external environment, endowing the mechanical metamaterials with reconfigurable characteristics.

[0078] The reconfigurable characteristics of the metamaterial are realized through the shape memory of the material, and the specific process is as follows: 1) Heat the mechanical metamaterial in the initial configuration (geometric parameter is A) above its glass transition temperature, and then apply a load to deform it; 2) Lower the temperature of the mechanical metamaterial below the glass transition temperature, and then unload it. The mechanical metamaterial can "remember" this temporary configuration (the geometric parameter changes from A to A'); 3) The mechanical metamaterial in the temporary configuration can independently withstand external loads at room temperature and exhibit mechanical properties different from those in the initial configuration; 4) Heat the metamaterial again, and the configuration of the metamaterial returns from the temporary configuration to its initial configuration (i.e., the geometric parameter changes from A' to A), and at the same time its mechanical properties also return to their initial state, thus completing the reconfiguration of the mechanical metamaterial. The mechanical metamaterial prepared by 4D printing exhibits the reconfiguration of properties such as Poisson's ratio, torsional-stretching coupling deformation characteristics, energy absorption characteristics, and vibration damping characteristics.

[0079] The device of this embodiment has the capabilities of self-adaptation, adjustable, and reconfigurable (including but not limited to configuration, vibration damping and energy absorption characteristics, mechanical characteristics, etc.). The specific implementation process is as follows: a) Under external excitation, heat the device above the glass transition temperature, and then apply a load to make it reach the target configuration / performance; b) Lower the temperature to the glass transition temperature, and the device can remain in the temporary configuration, and can independently withstand external loads and deform different mechanical properties / energy absorption characteristics / buffer characteristics, etc.; c) When applying external excitation to the device again, the device returns to its initial configuration, and its mechanical properties / energy absorption characteristics / buffer characteristics also return to their initial states. Among them, the forms of external excitation include but not limited to: thermal drive, magnetic drive, solution drive, radio frequency drive, microwave drive, light drive, combined drive.

[0080] For the driving method, if thermal drive is adopted, paste a resistive heater / an external heat source on the lower surface of the device for heating; if electric drive is adopted, the shape memory composite material should be doped with one or more of conductive reinforcing phases such as single-walled and multi-walled carbon nanotubes, graphene, carbon black, carbon nano paper, carbon nanofibers, short carbon fibers, continuous carbon fibers or hybrid particle filling, and there is an external power supply connected to the above doping phases to form a circuit; if microwave drive is adopted, the shape memory polymer composite material should be doped with nano particles such as carbon nanotubes, graphene oxide and silicon carbide; if radio frequency drive is adopted, the shape memory polymer composite material should be doped with radio frequency sensitive particles such as carbon nanotubes; if light drive is adopted, materials such as optical fibers should be buried in the shape memory polymer composite material; if combined drive is adopted, the reinforcing phases doped in the shape memory polymer composite material should include a combination of 2 or more of the above.

[0081] Different driving methods result in different driving processes of the device in this embodiment. Specifically, for example, in the case of thermal driving: the device is heated, and when the temperature reaches above the glass transition temperature, the device deforms from the temporary configuration to the initial configuration and then the heating stops. In the case of electric driving: an electric current is applied to the shape memory polymer composite material of the device, and when the temperature reaches above the glass transition temperature, the device deforms from the temporary configuration to the initial configuration and then the power supply stops. In the case of microwave driving: a microwave field is applied to the shape memory polymer composite material of the device, and when the temperature reaches above the glass transition temperature, the device deforms from the temporary configuration to the initial configuration and then the heating stops. In the case of radio frequency driving: a radio frequency field is applied to the shape memory composite material of the device, and when the temperature reaches above the glass transition temperature, the device deforms from the temporary configuration to the initial configuration and then the heating stops. In the case of optical driving: an optical field is applied to the shape memory composite material of the device, and when the temperature reaches above the glass transition temperature, the device deforms from the temporary configuration to the initial configuration and then the heating stops. In the case of combined driving: the corresponding excitation is applied to the selected combined driving method of the shape memory composite material of the device, and when the temperature reaches above the glass transition temperature, the device deforms from the temporary configuration to the initial configuration and then the heating stops.

[0082] The present invention will be described in detail below through two specific embodiments.

[0083] Embodiment 1: This embodiment provides a buffering and energy-absorbing device based on a 4D-printed multifunctional pixel mechanical metamaterial. As Figures 1 - 6 shown, the device is composed of a modular mechanical pixel structure 2 and a frame structure 1. According to the size of the precision instrument to be protected, the size and quantity of the mechanical pixel structure 2 of the device can be expanded. Similar to a display adjusting an image by adjusting the color of pixel points, the pixel mechanical metamaterial adjusts its macroscopic buffering / vibration damping performance by adjusting the configuration of the mechanical pixel structure 2. The mechanical pixel structure 2 is connected to the frame structure 1, and the individual mechanical pixel structures 2 are not connected to each other.

[0084] Among them, the modular mechanical pixel structure 2 is composed of 1 base module 9, 3 bistable modules, 2 compression-torsion coupling modules, 2 force threshold switch modules, and 1 top cover module 3. The structural schematic diagrams of each module are as Figure 7 、 Figure 8 shown. The top cover module 3 is connected to the upper part of the first bistable module 4. The lower part of the first bistable module 4 is connected to the upper end of the first compression-torsion coupling module 5. The lower end of the first compression-torsion coupling module 5 is connected to the upper part of the second bistable module 6. The lower part of the second bistable module 6 is connected to the upper end of the second compression-torsion coupling module 7. The lower end of the second compression-torsion coupling module 7 is connected to the upper part of the third bistable module 8. The lower part of the third bistable module 8 is connected to the upper end of the base module 9.

[0085] AsFigure 9 , Figure 10 As shown in Figure 10 , the bistable module is composed of 12 curved beams 41 to form a "field" - shaped structure, which has bistable deformation characteristics under external forces and can be switched between the first stable state and the second stable state by applying a load.

[0086] As Figures 11 - 14 shown in Figures 11 - 14 , the compression - torsion coupling module is composed of 4 helical ligaments 16, 2 upper and lower nodes connected to the bistable module, a plug 15, a rotation stopper 13, and a mounting groove 14 for installing the force - threshold switch module. The connection mode of the ligament 16 with the upper and lower nodes can be divided into a right - handed connection mode (as shown in Figure 11 , Figure 12 ) and a left - handed connection mode (as shown in Figure 13 , Figure 14 ). This chiral connection mode causes the module to generate torsional deformation under axial deformation.

[0087] As Figures 15 - 21 shown in Figures 15 - 21 , the force - threshold switch module and the compression - torsion module have 2 states, namely: the "ON" state and the "OFF" state. After the mechanical pixel structure 2 is fabricated, the plug 15 is on the upper surface of the force - threshold switch module, and it is in the "ON" state at this time (as shown in Figures 15 - 17 ). In this state, the mechanical pixel structure 2 will generate torsional deformation under an external axial load; when an external load is applied, the plug 15 is extruded from the through - hole of the force - threshold switch module and inserted into the rotation stopper 13, and it is in the "OFF" state at this time (as shown in Figures 18 - 21 ). The mechanical pixel structure 2 in the "OFF" state will not generate torsional deformation under an external load.

[0088] The mechanical pixel structure 2 of this embodiment is combined according to the 2 configurations (the first stable state and the second stable state) of the bistable module and the 2 configurations (ON and OFF) of the compression - torsion coupling module, and it has 32 stable and mutually - convertible programming configurations. Specifically, as Figure 22 shown in Figure 22 , it is the state after the mechanical pixel structure 2 is fabricated, denoted as configuration 1. At this time, the cooperation of the 2 compression - torsion coupling modules with the force - threshold switch module is in the "ON" state, and the 3 bistable modules are all in the first stable state. Under the action of an external compressive load, the mechanical pixel structure 2 of configuration 1 can generate 2 times of compression - torsion coupling deformation and 3 times of bistable deformation.

[0089] As Figure 23As shown, they are the configuration forms after programming one module in the mechanical pixel structure 2 relative to Configuration 1, denoted as Configuration 2-1, Configuration 2-2, Configuration 2-3, Configuration 2-4, and Configuration 2-5 respectively. In the cases of Configuration 2-1 and Configuration 2-2: The combination of one of the compression-torsion coupling modules and the force threshold switch module in the mechanical pixel structure 2 (hereinafter this combination may also be referred to as the compression-torsion and force threshold switch combination module. Correspondingly, the combination of the first compression-torsion coupling module 5 and the first force threshold switch module 10 is referred to as the first compression-torsion and force threshold switch combination module, and the combination of the second compression-torsion coupling module 7 and the second force threshold switch module 11 is referred to as the second compression-torsion and force threshold switch combination module) is in the OFF state. Under the action of an external compression load, the mechanical pixel structure 2 of Configuration 2-1 and Configuration 2-2 can produce one compression-torsion coupling deformation and three bistable deformations. In the cases of Configuration 2-3, Configuration 2-4, and Configuration 2-5: One of the bistable modules in the mechanical pixel structure 2 is in the second stable state. Under the action of an external compression load, the mechanical pixel structure 2 of Configuration 2-3, Configuration 2-4, and Configuration 2-5 can produce two compression-torsion coupling deformations and two bistable deformations.

[0090] Specifically, in Configuration 2-1, all three bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state. In Configuration 2-2, all three bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In Configuration 2-3, the first bistable module 4 is in the second stable state, the remaining two bistable modules are in the first stable state, and the two compression-torsion and force threshold switch combination modules are in the "ON" state. In Configuration 2-4, the third bistable module 8 is in the second stable state, the remaining two bistable modules are in the first stable state, and the two compression-torsion and force threshold switch combination modules are in the "ON" state. In Configuration 2-5, the second bistable module 6 is in the second stable state, the remaining two bistable modules are in the first stable state, and the two compression-torsion and force threshold switch combination modules are in the "ON" state.

[0091] As Figure 24As shown, it is the configuration form after programming two modules in the mechanical pixel structure 2 relative to configuration 1, denoted as configurations 3-1 to 3-10 respectively. In the case of configuration 3-1: The combination of two of the compression-torsion and force threshold switch combination modules and the force threshold switch module in the mechanical pixel structure 2 is in the OFF state. Under an external compressive load, the mechanical pixel structure 2 of configuration 3-1 can produce three bistable deformations. In the cases of configurations 3-2 to 3-7: One of the bistable modules in the mechanical pixel structure 2 is in the second stable state, and the combination of one compression-torsion and force threshold switch combination module and the force threshold switch module is in the OFF state. Under an external compressive load, the mechanical pixel structures 2 of configurations 3-2, 3-3, 3-4, 3-5, 3-6, and 3-7 can produce one compression-torsion coupling deformation and two bistable deformations. In the cases of configurations 3-8, 3-9, and 3-10: Two bistable modules in the mechanical pixel structure are in the second stable state. Under an external compressive load, the mechanical pixel structures of configurations 3-8, 3-9, and 3-10 can produce two compression-torsion coupling deformations and one bistable deformation.

[0092] Specifically, in configuration 3-1, all three bistable modules are in the first stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "OFF" state. In configuration 3-2, the third bistable module 8 is in the second stable state, the remaining two bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state. In configuration 3-3, the first bistable module 4 is in the second stable state, the remaining two bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state. In configuration 3-4, the second bistable module 6 is in the second stable state, the remaining two bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In configuration 3-5, the second bistable module 6 is in the second stable state, the remaining two bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state. In configuration 3-6, the third bistable module 8 is in the second stable state, the remaining two bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In configuration 3-7, the first bistable module 4 is in the second stable state, the remaining two bistable modules are in the first stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In configuration 3-8, the first bistable module 4 is in the first stable state, the remaining two bistable modules are in the second stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "ON" state. In configuration 3-9, the second bistable module 6 is in the first stable state, the remaining two bistable modules are in the second stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "ON" state. In configuration 3-10, the third bistable module 8 is in the first stable state, the remaining two bistable modules are in the second stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "ON" state.

[0093] Such as Figure 25As shown, it is the configuration form after programming 3 modules in the mechanical pixel structure 2 relative to configuration 1, denoted as configuration 4-1 to configuration 4-10 respectively. In the case of configuration 4-1: 3 of the bistable modules in the mechanical pixel structure 2 are in the second stable state. Under the action of an external compressive load, the mechanical pixel structure 2 of configuration 4-1 can produce 2 times of compressive-torsional coupling deformation. In the cases of configuration 4-2, 4-3 and 4-4: 1 of the bistable modules in the mechanical pixel structure 2 is in the second stable state, and 2 of the compressive-torsional and force threshold switch combination modules are in the OFF state. Under the action of an external compressive load, the mechanical pixel structure 2 of configuration 4-2, 4-3 and 4-4 can produce 2 times of bistable deformation. In the cases of configuration 4-5, configuration 4-6, configuration 4-7, configuration 4-8, configuration 4-9 and configuration 4-10: 2 of the bistable modules in the mechanical pixel structure 2 are in the second stable state, and 1 of the compressive-torsional and force threshold switch combination modules is in the OFF state. Under the action of an external compressive load, the mechanical pixel structure 2 of configuration 4-5, configuration 4-6, configuration 4-7, configuration 4-8, configuration 4-9 and configuration 4-10 can produce 1 time of bistable deformation and 1 time of compressive-torsional coupling deformation.

[0094] Specifically, in configuration 4-1, all three bistable modules are in the second stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "ON" state. In configuration 4-2, the first bistable module 4 is in the second stable state, the remaining two bistable modules are in the first stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "OFF" state. In configuration 4-3, the second bistable module 6 is in the second stable state, the remaining two bistable modules are in the first stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "OFF" state. In configuration 4-4, the third bistable module 8 is in the second stable state, the remaining two bistable modules are in the first stable state, and both of the two compression-torsion and force threshold switch combination modules are in the "OFF" state. In configuration 4-5, the second bistable module 6 is in the first stable state, the remaining two bistable modules are in the second stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In configuration 4-6, the third bistable module 8 is in the first stable state, the remaining two bistable modules are in the second stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In configuration 4-7, the first bistable module 4 is in the first stable state, the remaining two bistable modules are in the second stable state, the first compression-torsion and force threshold switch combination module is in the "OFF" state, and the second compression-torsion and force threshold switch combination module is in the "ON" state. In configuration 4-8, the third bistable module 8 is in the first stable state, the remaining two bistable modules are in the second stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state. In configuration 4-9, the second bistable module 6 is in the first stable state, the remaining two bistable modules are in the second stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state. In configuration 4-10, the first bistable module 4 is in the first stable state, the remaining two bistable modules are in the second stable state, the first compression-torsion and force threshold switch combination module is in the "ON" state, and the second compression-torsion and force threshold switch combination module is in the "OFF" state.

[0095] As Figure 26As shown, these are the configuration forms after programming 4 modules in the mechanical pixel structure 2 relative to configuration 1, denoted as configurations 5-1 to 5-5 respectively. In the cases of configurations 5-1, 5-4, and 5-5: 2 of the bistable modules in the mechanical pixel structure 2 are in the second stable state, and 2 of the combined torsion and force threshold switch modules are in the OFF state. Under an external compressive load, the mechanical pixel structure 2 of configurations 5-1, 5-4, and 5-5 can produce 1 bistable deformation. In the cases of configurations 5-2 and 5-3: 3 of the bistable modules in the mechanical pixel structure 2 are in the second stable state, and 1 of the combined torsion and force threshold switch modules is in the OFF state. Under an external compressive load, the mechanical pixel structure 2 of configurations 5-2 and 5-3 can produce 1 torsion-compression coupling deformation.

[0096] Specifically, in configuration 5-1, the first bistable module 4 is in the first stable state, and the other 2 bistable modules are both in the second stable state. The 2 combined torsion and force threshold switch modules are both in the "OFF" state. In configuration 5-2, the 3 bistable modules are all in the second stable state. The first combined torsion and force threshold switch module is in the "ON" state, and the second combined torsion and force threshold switch module is in the "OFF" state. In configuration 5-3, the 3 bistable modules are all in the second stable state. The first combined torsion and force threshold switch module is in the "OFF" state, and the second combined torsion and force threshold switch module is in the "ON" state. In configuration 5-4, the third bistable module 8 is in the first stable state, and the other 2 bistable modules are both in the second stable state. The 2 combined torsion and force threshold switch modules are both in the "OFF" state. In configuration 5-5, the second bistable module 6 is in the first stable state, and the other 2 bistable modules are both in the second stable state. The 2 combined torsion and force threshold switch modules are both in the "OFF" state.

[0097] As Figure 27 shown, this is the configuration form after programming 5 modules in the mechanical pixel structure 2 relative to configuration 1, denoted as configuration 6. In this configuration, 3 of the bistable modules in the mechanical pixel structure 2 are in the second stable state, and 2 of the combined torsion and force threshold switch modules are in the OFF state. Under an external compressive load, the mechanical pixel structure 2 of configuration 6 can produce 0 torsion-compression coupling deformations and 0 bistable deformations.

[0098] Embodiment 2: The buffering and energy absorption device of the 4D printing multifunctional pixel mechanical metamaterial provided in this embodiment is composed of a mechanical pixel structure 2 and a frame structure 1. Among them, the mechanical pixel structure 2 is still composed of 1 base module 9, 3 bistable modules, 2 compression-torsion coupling modules, 2 force threshold switch modules, and 1 top cover module 3. However, the connection method of each module is different from that in Embodiment 1. By adding a bistable connection module 19 and a compression-torsion connection module 12, the connection between bistable modules and the connection between compression-torsion coupling modules can be realized.

[0099] As Figures 31 - 34 shown, the top cover module 3 is connected to the upper part of the first bistable module 4. The lower part of the first bistable module 4 is connected to the upper part of the second bistable module 6 through the bistable connection module 19. The lower part of the second bistable module 6 is connected to the upper end of the first compression-torsion coupling module 5 through the bistable connection module 19 and the compression-torsion connection module 12. The lower end of the first compression-torsion coupling module 5 is connected to the upper end of the second compression-torsion coupling module 7 through the compression-torsion connection module 12. The lower end of the second compression-torsion coupling module 7 is connected to the upper part of the third bistable module 8. The lower part of the third bistable module 8 is connected to the upper end of the base module 9. Among them, the structures of the bistable connection module 19 and the compression-torsion connection module 12 are as Figure 32 , Figure 33 shown.

[0100] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A buffering and energy-absorbing device based on a 4D-printed multifunctional pixel mechanical metamaterial, characterized in that, Including: A frame structure (1) and a plurality of mechanical pixel structures (2), and the plurality of mechanical pixel structures (2) are independently arranged within the frame structure (1); The mechanical pixel structure (2) includes a top cover module (3), at least one bistable module, at least one compression-torsion coupling module, at least one force threshold switch module, a base module (9), and a connection module; at least one of the bistable modules and at least one of the compression-torsion coupling modules are interconnected between the top cover module (3) and the base module (9), and each module of the mechanical pixel structure (2) is directly connected or connected through the connection module. Among them, the materials used for each module of the mechanical pixel structure (2) have shape memory characteristics. The bistable module is used to generate bistable deformation, and the compression-torsion coupling module is used to generate compression-torsion coupling deformation; the number of the force threshold switch modules is equal to the number of the compression-torsion coupling modules. The force threshold switch module is installed within the compression-torsion coupling module and is used to control the opening or closing of the torsional deformation of the compression-torsion coupling module. The compression-torsion coupling module includes a first node (17), a second node (18), a ligament (16), a plug (15), and a rotation stopper (13). The first node (17) and the second node (18) are oppositely arranged. The plug (15) is arranged at the first node (17), and the rotation stopper (13) is arranged at the second node (18). The plug (15) is used to be inserted into the rotation stopper (13). The force threshold switch module includes a housing, the interior of the housing is hollow, and one end of the housing is open and the other end is provided with a through hole. The housing covers the outside of the rotation stopper (13), and the housing is coaxially arranged with the rotation stopper (13) and the plug (15). A second protrusion is arranged on the outer wall of the plug (15), and the second protrusion can be extruded through the through hole.

2. The buffer and energy absorption device based on the 4D printing multifunctional pixel mechanical metamaterial according to claim 1, wherein The ligament (16) is connected between the first node (17) and the second node (18), and the connection of the ligament (16) with the first node (17) and the second node (18) includes a right-handed connection mode and a left-handed connection mode.

3. The buffer and energy absorption device based on the 4D printed multifunctional pixel mechanical metamaterial according to claim 2, wherein The rotation stopper (13) includes a base, the base is arranged on the second node (18), a groove structure is formed on the top surface of the base, and a first protrusion is arranged at one end of the plug (15) close to the rotation stopper (13). The first protrusion is used to be inserted into the groove structure.

4. The buffer and energy absorption device based on the 4D printing multifunctional pixel mechanical metamaterial according to claim 3, characterized in that, The groove structure includes a first groove and a plurality of second grooves. The first groove is arranged at the center of the top surface of the base and is coaxially arranged with the plug (15). The plurality of second grooves are radially distributed along the circumference of the first groove, and the plurality of second grooves communicate with the first groove. The number of the first protrusions is less than or equal to the number of the second grooves, and the plurality of first protrusions are simultaneously inserted into the second grooves.

5. The buffer and energy absorption device based on the 4D printing multifunctional pixel mechanical metamaterial according to claim 2, characterized in that, An installation groove (14) is provided on the second node (18), and the installation groove (14) is used to install the force threshold switch module.

6. The buffer and energy absorption device based on the 4D printed multifunctional pixel mechanical metamaterial according to claim 1, characterized in that, The modules of the mechanical pixel structure (2) are connected by a quick-release pin structure, a mortise and tenon structure, adhesion or integral molding.

7. The buffer and energy absorption device based on the 4D printing multifunctional pixel mechanical metamaterial according to claim 2, characterized in that, The bistable module is composed of twelve curved beams (41), and the twelve curved beams (41) form a "field" - shaped structure. The "field" - shaped structure has two stable states, and the two stable states are used for conversion under the action of a load.

8. The buffer and energy absorption device based on the 4D printing multifunctional pixel mechanical metamaterial according to claim 7, characterized in that, Bistable connection columns (42) are provided at the midpoints of the four sides, the center point, and the four vertices of the "field" - shaped structure. The bistable connection columns (42) at the midpoints of the four sides of the "field" - shaped structure and the bistable connection columns (42) at the center point and the four vertices of the "field" - shaped structure are respectively located on two opposite faces of the "field" - shaped structure. A press - torsion connection groove structure is provided on the first node (17) and the second node (18) of the press - torsion coupling module. A top - cover connection groove structure is provided at the bottom of the top - cover module (3), and a base - connection groove structure is provided at the top of the base module (9). The bistable connection column (42) is used for mating connection with the press - torsion connection groove structure, the top - cover connection groove structure, or the base - connection groove structure.

9. The buffer and energy absorption device based on the 4D printing multifunctional pixel mechanical metamaterial according to claim 8, characterized in that, The connection module includes a bistable connection module (19). Adjacent two bistable modules are connected by the bistable connection module (19). The bistable connection module (19) includes a first substrate (1901) and a first connection groove structure (1902). The first connection groove structure (1902) is provided at the center point, the four vertices, and the midpoints of the four sides of the first substrate (1901). The first connection groove structures (1902) at the center point and the four vertices of the first substrate (1901) and the first connection groove structures (1902) at the midpoints of the four sides of the first substrate (1901) are respectively located on two opposite faces of the first substrate (1901). The first connection groove structure (1902) is used for mating connection with the bistable connection column (42).

10. The buffer and energy absorption device based on the 4D printed multifunctional pixel mechanical metamaterial according to claim 9, characterized in that, The connection module further includes a press - torsion connection module (12). Adjacent two press - torsion coupling modules are connected by the press - torsion connection module (12). The press - torsion connection module (12) includes a second substrate (1201) and a second connection column (1202). The second connection column (1202) is provided at the center point, the four vertices, and the midpoints of the four sides of the second substrate. The second connection columns (1202) at the center point and the four vertices of the second substrate (1201) and the second connection columns (1202) at the midpoints of the four sides of the second substrate (1201) are respectively located on two opposite faces of the second substrate (1201). The second connection column (1202) is used for mating connection with the press - torsion connection groove structure or the first connection groove structure (1902).

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