An integrally manufactured static mechanical non-reciprocal metamaterial unit

Abstract

The application discloses a static mechanical non-reciprocal metamaterial unit manufactured integrally, and belongs to the technical field of non-reciprocal metamaterials. The unit comprises a main support, a load-receiving piece, at least one locking rib and at least one stopper. A plurality of fixed ribs are arranged on a fixed part of the main support in a first direction. The load-receiving piece and the fixed part are arranged in a second direction and are movably connected to the main support in the first direction. One end of each locking rib is rotatably connected to the load-receiving piece around a first axis. The end of the first locking rib of the locking rib, which is away from the load-receiving piece, is located between two adjacent fixed ribs. Each stopper is arranged on the load-receiving piece and is located on the side of the corresponding locking rib, which is close to a load source. In the no-load state of the load-receiving piece, the distance between the stopper and the adjacent fixed rib on the side of the stopper, which is close to the load source, is greater than or equal to zero in the second direction. The first direction, the second direction and the first axis are perpendicular to each other.

Description

Technical Field

[0001] This application relates to the field of non-reciprocal metamaterials technology, specifically to an integrally manufactured static mechanical non-reciprocal metamaterial unit. Background Technology

[0002] Traditional mechanical structures typically satisfy the Maxwell-Bettie reciprocity theorem, meaning that under forward and reverse loading conditions, the mechanical transmission relationship of the structure usually exhibits a symmetrical response. However, in applications such as unidirectional mechanical transmission, impact protection, directional energy regulation, vibration damping, and intelligent mechanical actuation, structures often need to exhibit significantly different stiffness, deformation modes, or transmission characteristics under different loading directions. Therefore, there is a demand for structures with non-reciprocal static mechanical responses.

[0003] To meet the aforementioned requirement for non-reciprocal static mechanical response, related technologies have developed structures capable of achieving unidirectional mechanical effects. These structures can be mainly divided into the following two categories. One category is traditional mechanical unidirectional mechanisms, such as mechanical ratchet mechanisms and unidirectional clutches. These structures typically rely on the meshing, locking, or rolling cooperation between multiple independent components to achieve unidirectional locking or unidirectional transmission.

[0004] Another type is the passive geometrically non-reciprocal metamaterial, which has been developed in recent years. These structures typically rely on fixed asymmetric geometries, such as inclined ribs, cantilever beams, locally buckling elements, or ratchet-like serrated links, to achieve a static mechanical non-reciprocal response through the difference in nonlinear deformation paths under different loading directions. These structures have advantages such as requiring no external energy input and being suitable for array design, but they usually suffer from high reverse drag and limited non-reciprocal performance. Summary of the Invention

[0005] This application provides an integrally manufactured static mechanical non-reciprocal metamaterial unit to solve the problems of large reverse resistance and limited non-reciprocal properties in related technologies.

[0006] To achieve the above objectives, the embodiments of this application disclose the following technical solutions: This application provides an integrated static mechanical non-reciprocal metamaterial unit, including a main support, a load-bearing component, at least one locking rib, and at least one stop. The main support includes a fixing part with multiple fixing ribs spaced apart along a first direction. The load-bearing component is spaced apart from the fixing part in a second direction and movably connected to the main support along the first direction, wherein the second direction is perpendicular to the first direction. One end of each locking rib is rotatably connected to the load-bearing component about a first axis, which is perpendicular to both the first and second directions. At least one locking rib includes a first locking rib, the end of which is located away from the load-bearing component between two adjacent fixing ribs. Each stop is provided on the load-bearing component, with each locking rib corresponding to one stop, and each stop is located on the side of its corresponding locking rib closer to the load source to restrict the rotation of its corresponding locking rib. In the unloaded state of the load-bearing component, the distance between the stop along the second direction and the adjacent fixing rib located on its side closer to the load source is greater than or equal to zero.

[0007] With this configuration, by placing the stop on the load-bearing member and on the side of the locking rib closer to the load source of the load-bearing member, and ensuring that the distance between the stop and the adjacent fixed rib on the side closer to the load source in the second direction is greater than or equal to zero when the load-bearing member is unloaded, it can be guaranteed that when the load-bearing member moves in the first direction toward the load source (i.e., is subjected to reverse force), there is no interference between the stop and the fixed rib, thereby allowing the locking rib to make smooth contact with the adjacent fixed rib on the side closer to the load source.

[0008] Based on this, since the locking rib has the degree of freedom to rotate about the first axis away from the stop, when the locking rib comes into contact with a fixed rib located on its side closer to the load source, the locking rib can avoid contact by rotating about the first axis away from the stop. In this way, the locking rib's avoidance method can be changed from primarily relying on material bending, local buckling, or tooth surface overturning to primarily relying on mechanical rotation. This reduces the motion resistance (the aforementioned reverse resistance) of the loaded component when moving towards the load source, improves the non-reciprocity ratio, and solves the problem in related technologies where static mechanical non-reciprocal structures experience high resistance and limited non-reciprocity response when bearing loads on the loaded component towards the load source.

[0009] In addition, by placing the stop on the loaded member and positioning it on the side of the locking rib closer to the load source, the rotational range of the first locking rib towards the load source can be limited. This allows the first locking rib to form a stable abutment and locking relationship with the adjacent fixed rib located on its side away from the load source when the loaded member moves away from the load source along the first direction (i.e., under positive force). In this way, the resistance to reverse movement is reduced while maintaining positive locking stability.

[0010] In some possible implementations, the locking rib is rotatably connected to the load-bearing member via a hinge. This arrangement utilizes the low-friction rotational characteristics provided by the hinge, allowing the locking rib to rotate about the first axis with less driving force as the load-bearing member moves toward the load source. This further reduces the overall drag of the statically non-reciprocal metamaterial unit in that direction of movement.

[0011] In some possible implementations, the hinge includes a pivot seat and a pivot. The pivot seat is mounted on the load-bearing component and has two plates facing each other in a third direction. The third direction is parallel to the first axis, and rotating posts are provided on the surfaces of the two plates facing each other. The pivot has rotating holes on both end faces in its axial direction, and these holes are fitted into the two rotating posts in a one-to-one correspondence. A locking rib is fixedly connected to the pivot. This configuration eliminates the need for additional pins or fasteners for the rotational connection between the locking rib and the load-bearing component. This simplifies the manufacturing process.

[0012] In some possible implementations, the rotating column and its corresponding rotating hole are clearance-fitted. This creates a pre-existing clearance between the pivot and the pivot seat. This allows the pivot and pivot seat to be directly formed in an integrated manufacturing process (e.g., additive manufacturing), eliminating subsequent assembly steps and simplifying the manufacturing process. Furthermore, it avoids problems such as pivot jamming or inability to rotate due to overly tight fits, ensuring that the locking rib can smoothly avoid contact with the adjacent fixed rib located near the load source through rigid rotation.

[0013] In some possible implementations, on any mating section perpendicular to the first axis, the difference between the radius of the rotating hole and the radius of the rotating column is greater than or equal to 0.4 mm and less than or equal to 1 mm. The difference between the minimum distance between the two rotating pillars and the minimum distance between the two rotating holes is greater than or equal to 0.4 mm and less than or equal to 1 mm. This ensures that the radial and axial clearances between the rotating holes and rotating pillars are controlled within a reasonable range that accommodates dimensional deviations generated during integrated additive manufacturing without being excessive and affecting the stability of the fit. This avoids rotational jamming caused by excessively small clearances, thus improving non-reciprocal response; and it also prevents loosening of the hinge fit and pivot disengagement under load due to excessively large clearances. Furthermore, when integrated static mechanical non-reciprocal metamaterial units are formed using additive manufacturing, it also avoids limitations on printing accuracy due to excessively small clearances and prevents rotational jamming caused by localized adhesion. Therefore, it ensures that the integrated static mechanical non-reciprocal metamaterial units can be smoothly debonded after integrated manufacturing while maintaining their structural stability.

[0014] In some possible implementations, there are two fixing parts, which are arranged at intervals relative to each other along the second direction and are mirror-symmetrical; the main support also includes a connecting part, which connects the two fixing parts to the ends away from the load source; The load-bearing component is located between the two fixed parts and on the side of the connection part closer to the load source; the integrated static mechanical non-reciprocal metamaterial unit also includes two locking rib assemblies, each of which includes at least a first locking rib; the two locking rib assemblies are arranged one-to-one with the two fixed parts.

[0015] This configuration allows the ends of the two fixed parts furthest from the load source to be connected as a rigid frame via a connecting part, maintaining the relative positional stability of the two fixed parts and preventing changes in the distance between the fixing ribs and locking ribs due to deformation of the fixed parts. Furthermore, by arranging the two fixed parts in a mirror-symmetrical manner with relative spacing along the second direction, and placing the load-bearing component between the two fixed parts, with each of the two locking rib assemblies corresponding one-to-one with the two fixed parts, the locking ribs located on both sides of the load-bearing component can simultaneously form a symmetrical contact engagement with the fixing ribs on the two fixed parts when the load-bearing component moves along the first direction. This results in a more balanced force distribution and smoother movement of the load-bearing component. Consequently, the structural stability and operational reliability of the integrally manufactured static mechanical non-reciprocal metamaterial unit are improved.

[0016] In some possible implementations, along the first direction, the distance between the load-bearing end of the loaded member and the connecting portion is greater than the distance between the end of the fixed portion closer to the load source and the connecting portion. This allows the load-bearing end to protrude beyond the end of the fixed portion away from the connecting portion in the first direction. Consequently, it ensures that external loads act preferentially on the load-bearing end, thus directly transmitting the external load to the loaded member. This ensures that the loaded member accurately responds to the amplitude and direction of the external load, improving the non-reciprocal response accuracy and reliability of the integrated static mechanical non-reciprocal metamaterial unit.

[0017] In some possible implementations, the locking rib assembly includes multiple locking ribs, each corresponding to a plurality of fixed ribs. The end of each locking rib furthest from the load-bearing member is located on the side of its corresponding fixed rib near the connection. Thus, when the load-bearing member moves along the first direction, the load can be simultaneously distributed across the multiple locking ribs and fixed ribs. This improves the load-bearing capacity of the integrally manufactured statically non-reciprocal metamaterial unit in the locking direction.

[0018] In some possible implementations, the load-bearing component is movably connected to the main support along a first direction via an elastic connector located between the load-bearing component and the connecting portion. Thus, when the external load on the load-bearing component disappears, the elastic connector can use its stored elastic potential energy to drive the load-bearing component to automatically reset. In this way, the integrally manufactured statically non-reciprocal metamaterial unit can possess the ability to respond to cyclic loads.

[0019] In some possible implementations, the end of the locking rib furthest from the load-bearing member has a locking plane and a clearance plane. The locking plane is closer to the connecting portion than the clearance plane, and there is an angle between the locking plane and the clearance plane. When the load-bearing member moves a predetermined distance toward the connecting portion, the locking rib forms surface contact with the adjacent fixed rib located on its side near the connecting portion through the locking plane, thus achieving self-locking. This configuration, by allowing the locking rib to form surface contact with the adjacent fixed rib located on its side near the connecting portion through the locking plane, increases the contact area between the locking rib and the fixed rib, avoiding localized stress concentration. This, in turn, improves the stability and reliability of the locking state of the integrally manufactured static mechanical non-reciprocal metamaterial unit. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an integrally manufactured static mechanical non-reciprocal metamaterial unit provided for some embodiments of this application.

[0021] Figure 2 for Figure 1 A partial structural schematic diagram of a statically non-reciprocal metamaterial unit manufactured in one piece. Figure 3 for Figure 2 The diagram shows the assembly of the hinge and the load-bearing component in the structure shown.

[0022] Figure 4 for Figure 1 The diagram shows a structural schematic of a statically non-reciprocal metamaterial unit manufactured in one piece, viewed from another perspective.

[0023] Figure 5 This is a structural diagram for comparison.

[0024] Figure 6 for Figure 5 The structure shown is Figure 4 The diagram shows a comparison of the force-displacement curves for the structure in both positive and negative directions.

[0025] Figure 7 for Figure 5 The structure shown is the same as Figure 4 The diagram shows a comparison of the non-reciprocity ratio of the structure as a function of displacement.

[0026] Figure 8 for Figure 5 The structure shown is Figure 4 The diagram shows the positive force-displacement comparison curves of the structure.

[0027] Figure 9 A comparison curve of positive force-displacement for hinges with reserved gaps of 1mm and 1.2mm.

[0028] Figure 10 A graph comparing the force-displacement curves of a hinge after 500 bends with one before bending.

[0029] Explanation of reference numerals in the attached figures: 1. Main support; 11. Fixing part; 111. Fixing rib; 12. Connecting part; 2. Load-bearing component; 21. Load-bearing end; 3. Locking rib assembly; 31. Locking rib; 311. Locking plane; 312. Clearance plane; 31a. First locking rib; 4. Stop part; 5. Hinge; 51. Pivot seat; 511. Plate; 512. Rotating column; 52. Pivot; 521. Rotating hole; 6. Elastic connecting component. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In the embodiments of this application, the terms "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0032] In the description of the embodiments of this application, the term "multiple" means two or more.

[0033] In the description of the embodiments of this application, the term "and / or" refers to and covers any and all possible combinations of one or more of the associated listed items. The term "and / or" describes an association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "or" relationship.

[0034] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "installation", "connection" and "linking" should be interpreted broadly. For example, "linking" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0035] In the description of embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0036] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable deviation range, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where the acceptable deviation range for approximate parallelism can be, for example, within ±10°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where the acceptable deviation range for approximate perpendicularity can also be, for example, within ±10°; “equal” includes absolute equality and approximate equality, where the acceptable deviation range for approximate equality can be, for example, a difference between the two equals less than or equal to 5% of either one.

[0037] As mentioned in the background section above, traditional mechanical structures typically satisfy the Maxwell-Bettie reciprocity theorem, meaning that under forward and reverse loading conditions, the mechanical transmission relationship of the structure usually exhibits a symmetrical response. However, in applications such as unidirectional mechanical transmission, impact protection, directional energy regulation, vibration damping, and intelligent mechanical actuation, structures often need to exhibit significantly different stiffness, deformation modes, or transmission characteristics under different loading directions. Therefore, there is a demand for structures with static mechanical non-reciprocal responses.

[0038] To meet the aforementioned requirement for non-reciprocal static mechanical response, related technologies have developed structures capable of achieving unidirectional mechanical effects. These structures can be mainly divided into two categories. One category is traditional mechanical unidirectional mechanisms, such as mechanical ratchet mechanisms and unidirectional clutches. These structures typically rely on the meshing, locking, or rolling cooperation between multiple independent components to achieve unidirectional locking or unidirectional transmission. Although such structures can achieve direction-selective mechanical responses, they usually suffer from problems such as a large number of components, complex assembly processes, unavoidable assembly errors and clearances, significant friction and wear, and difficulty in achieving miniaturization and integrated manufacturing.

[0039] Another type, passive geometrically non-reciprocal metamaterials developed in recent years, typically rely on fixed asymmetric geometric configurations, such as inclined ribs, cantilever beams, locally buckling elements, or ratchet-like serrated links. They achieve static mechanical non-reciprocal responses through differences in nonlinear deformation paths under different loading directions. These structures offer advantages such as requiring no external energy input and suitability for array design. However, they often suffer from significant reverse drag and limited non-reciprocal performance, especially when using additive manufacturing processes such as fused deposition modeling and conventional polymer materials like polylactic acid (PLA) and thermoplastic polyurethane elastomers for integrated molding.

[0040] The root cause lies in the fact that the reverse avoidance process of this type of structure relies excessively on the elastic bending deformation, local buckling behavior, or overturning friction between the tooth surfaces of the components. Specifically, for structures using fixed serrated ribs, when subjected to reverse loading, the yielding action relies on the coordinated deformation of the ribs, the main frame, and the elastic connection area. The bending deformation of the ribs and the friction of the contact interface significantly increase the reverse base resistance, making it difficult for the structure to further reduce the reverse resistance while maintaining the high stiffness of the positive contact self-locking mechanism. This limits the improvement of the non-reciprocity ratio and hinders its widespread application in fields such as efficient unidirectional mechanical transfer, directional energy management, and vibration damping.

[0041] To resolve the above technical issues, please refer to [link / reference]. Figure 1 , Figure 1 This is a schematic diagram of the structure of an integrally manufactured static mechanical non-reciprocal metamaterial unit 100 provided in some embodiments of this application. Embodiments of this application provide an integrally manufactured static mechanical non-reciprocal metamaterial unit 100, including a main support 1, a load-bearing component 2, at least one locking rib 31, and a stop portion 4. The main support 1 includes a fixing portion 11. Exemplarily, the specific shape of the fixing portion 11 can be designed according to actual application needs, for example, it can be a plate-like structure, a rod-like structure, or other equivalent configurations.

[0042] The fixing part 11 is provided with a plurality of fixing ribs 111 arranged at intervals along a first direction. Exemplarily, the plurality of fixing ribs 111 on the fixing part 11 can be arranged at equal intervals along the first direction or at non-equal intervals along the first direction. The tooth profile of the plurality of fixing ribs 111 can be triangular, trapezoidal, sawtooth, or other asymmetrical tooth profile, as long as it can achieve unidirectional locking when engaged with the locking rib 31.

[0043] The load-bearing member 2 and the fixing part 11 are arranged at intervals in the second direction and are movably connected to the main body support 1 in the first direction (that is, the load-bearing member 2 can be displaced relative to the main body support 1 in the first direction). The second direction is perpendicular to the first direction.

[0044] Each locking rib 31 has one end rotatably connected to the load-bearing member 2 about a first axis A1. The first axis A1 is perpendicular to both a first direction and a second direction. Exemplarily, the locking rib 31 can be a rod-shaped or arm-shaped member that transmits force between the load-bearing member 2 and the fixed ribs 111. The at least one locking rib 31 includes a first locking rib 31a. The end of the first locking rib 31a away from the load-bearing member 2 is located between two adjacent fixed ribs 111 so as to engage with different fixed ribs 111 when the load-bearing member 2 moves in different directions.

[0045] Each stop 4 is provided on the load-bearing member 2. Exemplarily, the stop 4 may be, but is not limited to, a protrusion extending from the load-bearing member 2 toward the locking rib 31. Each locking rib 31 corresponds to one stop 4, and each stop 4 is located on the side of its corresponding locking rib 31 closer to the load source to restrict the rotation of its corresponding locking rib 31; in the unloaded state of the load-bearing member 2, the distance between the stop 4 and the adjacent fixed rib 111 located on its side closer to the load source is greater than or equal to zero in the second direction. Here, the so-called unloaded state refers to the state when the load-bearing member 2 is not subjected to external load.

[0046] With this configuration, by placing the stop 4 on the load-bearing member 2 and on the side of the locking rib 31 close to the load source of the load-bearing member 2, and ensuring that the distance between the stop 4 and the fixed rib 111 located on the side close to the load source of the load-bearing member 2 in the second direction is greater than or equal to zero when the load-bearing member 2 is unloaded, it can be guaranteed that when the load-bearing member 2 moves in the first direction towards the load source (i.e., is subjected to reverse force), there is no interference between the stop 4 and the fixed rib 111, thereby enabling the locking rib 31 to make smooth contact with the fixed rib 111 located on the side close to the load source of the load-bearing member 2.

[0047] Based on this, since the locking rib 31 has the degree of freedom to rotate about the first axis A1 in a direction away from the stop 4, when the locking rib 31 comes into contact with the fixed rib 111 located on its side closer to the load source and adjacent to it, the locking rib 31 can avoid contact by rotating about the first axis A1 in a direction away from the stop 4. In this way, the avoidance method of the locking rib 31 can be changed from being mainly based on material bending, local buckling, or tooth surface overturning to being mainly based on mechanical rotation. As a result, the motion resistance of the loaded member 2 when moving towards the load source (the reverse resistance mentioned above) can be reduced, the non-reciprocity ratio can be improved, and the problem of large resistance and limited non-reciprocity response of static mechanical non-reciprocal structures in related technologies when bearing loads on the loaded member 2 towards the load source can be solved.

[0048] In addition, by providing the stop 4 on the load-bearing member 2 and located on the side of the locking rib 31 closer to the load source of the load-bearing member 2, the rotation amplitude of the first locking rib 31a in the direction of the load source can be limited. This allows the first locking rib 31a to form a stable abutment and locking relationship with the adjacent fixed rib 111 located on its side away from the load source when the load-bearing member 2 moves away from the load source along the first direction (i.e., under positive force). In this way, the resistance to reverse movement is reduced while maintaining positive locking stability.

[0049] Please see Figure 2 , Figure 2 for Figure 1This is a partial structural schematic diagram of the integrally manufactured static mechanical non-reciprocal metamaterial unit 100. In some embodiments, the locking rib 31 is rotatably connected to the load-bearing member 2 via a hinge 5. This arrangement utilizes the low-friction rotational characteristics provided by the hinge 5, allowing the locking rib 31 to rotate about the first axis A1 with less driving force when the load-bearing member 2 moves towards the load source. This further reduces the overall drag of the static mechanical non-reciprocal metamaterial unit in this direction of movement.

[0050] It is understood that the rotatable connection between the locking rib 31 and the load-bearing member 2 via the hinge 5 is one example of a rotatable connection between the locking rib 31 and the load-bearing member 2. In other embodiments, the locking rib 31 and the load-bearing member 2 may also be connected by a pin or other connection methods that enable relative rotation. When a pin connection is used, the pin can pass through a through hole in both the load-bearing member 2 and the locking rib 31, allowing the locking rib 31 to rotate about the pin.

[0051] Please see Figure 2 and Figure 3 ,in, Figure 3 for Figure 2 The diagram shows the assembly of hinge 5 and load-bearing member 2 in the structure shown. In some embodiments, hinge 5 includes a pivot seat 51 and a pivot 52. The pivot seat 51 is mounted on the load-bearing member 2 and has two plates 511 arranged opposite each other in a third direction, which provide rotational support for the pivot 52. The third direction is parallel to the first axis A1, and rotating posts 512 are provided on the surfaces of the two plates 511 facing each other. The pivot 52 has rotating holes 521 on both end faces in its own axial direction. The two rotating holes 521 are inserted into the two rotating posts 512 in a one-to-one correspondence. Locking ribs 31 are fixedly connected to the pivot 52.

[0052] This design eliminates the need for additional pins or fasteners for the rotatable connection between the locking rib 31 and the load-bearing member 2. This simplifies the manufacturing process.

[0053] In some embodiments, the rotating column 512 is clearance-fitted with its corresponding rotating hole 521. This creates a reserved fit clearance between the pivot 52 and the pivot seat 51. This allows the pivot 52 and pivot seat 51 to be directly formed in an integrated manufacturing process (e.g., additive manufacturing), eliminating subsequent assembly steps and simplifying the manufacturing process. Furthermore, it avoids the problem of the pivot 52 becoming stuck or unable to rotate due to an overly tight fit, ensuring that the locking rib 31 can smoothly avoid contact with the adjacent fixed rib 111 located near the load source through rigid rotation.

[0054] Please see Figure 3In some embodiments, at any mating cross-section perpendicular to the first axis A1, the difference between the radius of the rotating hole 521 and the radius of the rotating column 512 is greater than or equal to 0.4 mm and less than or equal to 1 mm. The mating cross-section refers to the section perpendicular to the first axis A1 at the position where the rotating column 512 and the rotating hole 521 mate. For example, at any mating cross-section perpendicular to the first axis A1, the difference between the radius of the rotating hole 521 and the radius of the rotating column 512 can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm.

[0055] The difference between the minimum distance between the two rotating posts 512 and the minimum distance between the two rotating holes 521 is greater than or equal to 0.4 mm and less than or equal to 1 mm. For example, the difference between the minimum distance between the two rotating posts 512 and the minimum distance between the two rotating holes 521 can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm or 0.9 mm.

[0056] In this way, the radial and axial clearances between the rotating hole 521 and the rotating column 512 can be controlled within a reasonable range that can accommodate the dimensional deviations generated during the integrated additive manufacturing process without being too large and affecting the stability of the fit.

[0057] In this way, on the one hand, it can avoid the rotation jamming caused by too small a gap, thereby improving the non-reciprocal response; on the other hand, it can avoid the problems of loosening of the hinge 5 due to too large a gap and the pivot 52 dislodging from the pivot seat 51 under load.

[0058] Furthermore, when the integrated static mechanical non-reciprocal metamaterial unit 100 is formed using additive manufacturing, on the one hand, the printing accuracy can be avoided due to excessively small gaps; on the other hand, rotational jamming caused by local adhesion can be avoided. Thus, it can be ensured that the integrated static mechanical non-reciprocal metamaterial unit 100 can be smoothly debonded after integrated manufacturing, while also taking into account the structural stability of the integrated static mechanical non-reciprocal metamaterial unit 100.

[0059] Please see Figure 4 , Figure 4 for Figure 1 The diagram shows a structural schematic of the integrally manufactured static mechanical non-reciprocal metamaterial unit 100 from another perspective. In some embodiments, there are two fixing parts 11. The two fixing parts 11 are arranged at a distance from each other along a second direction and are mirror-symmetrical. The main support 1 also includes a connecting part 12, which connects the two fixing parts 11 at the ends away from the load source. The aforementioned load-bearing member 2 is located between the two fixing parts 11 and on the side of the connecting part 12 closer to the load source.

[0060] The integrated static mechanical non-reciprocal metamaterial unit 100 also includes two locking rib assemblies 3, each including at least a first locking rib 31a. The two locking rib assemblies 3 are correspondingly arranged with the two fixing parts 11. This arrangement allows the ends of the two fixing parts 11 furthest from the load source to be connected as a rigid frame via the connecting part 12, maintaining the relative positional stability of the two fixing parts 11 and preventing changes in the distance between the fixing ribs 111 and the locking ribs 31 due to deformation of the fixing parts 11.

[0061] Based on this, by arranging the two fixing parts 11 relatively spaced apart and mirror-symmetrically along the second direction, and placing the load-bearing member 2 between the two fixing parts 11, with the two locking rib assemblies 3 corresponding one-to-one with the two fixing parts 11, when the load-bearing member 2 moves along the first direction, the locking ribs 31 located on both sides of the load-bearing member 2 can simultaneously form a symmetrical contact engagement with the fixing ribs 111 on the two fixing parts 11. This allows for more balanced force distribution and smoother movement of the load-bearing member 2. Consequently, the structural stability and operational reliability of the integrated static mechanical non-reciprocal metamaterial unit 100 can be improved.

[0062] Please see Figure 4 In some embodiments, along the first direction, the distance between the load-bearing end 21 of the load-bearing member 2 and the connecting portion 12 is greater than the distance between the end of the fixing portion 11 near the load source and the connecting portion 12. The load-bearing end 21 is the end of the load-bearing member 2 that directly bears the external load.

[0063] In this way, the load-bearing end 21 can protrude from the end of the fixing part 11 away from the connecting part 12 in the first direction. This ensures that external loads act preferentially on the load-bearing end 21, thereby directly transmitting the external load to the load-bearing member 2. This ensures that the load-bearing member 2 accurately responds to the amplitude and direction of the external load, improving the non-reciprocal response accuracy and reliability of the integrated static mechanical non-reciprocal metamaterial unit 100.

[0064] It is understandable that the distance between the load-bearing end 21 of the load-bearing member 2 and the connecting portion 12 is greater than the distance between the end of the fixing portion 11 away from the connecting portion 12 and the connecting portion 12. This is one example of the positional relationship of the load-bearing end 21 in the first direction. In other embodiments, the distance between the load-bearing end 21 of the load-bearing member 2 and the connecting portion 12 may also be equal to the distance between the end of the fixing portion 11 away from the connecting portion 12 and the connecting portion 12. That is, the load-bearing end 21 and the end of the fixing portion 11 away from the connecting portion 12 are flush in the first direction.

[0065] Please see Figure 4 In some embodiments, the locking rib assembly 3 has multiple locking ribs 31. Exemplarily, in... Figure 4In the illustrated embodiment, the locking rib assembly 3 has three locking ribs 31. In other embodiments, the locking rib assembly 3 may have two, four, or more locking ribs 31, depending on the actual requirements.

[0066] Multiple locking ribs 31 are arranged in a one-to-one correspondence with multiple fixing ribs 111. The end of each locking rib 31 away from the load-bearing member 2 is located on the side of its corresponding fixing rib 111 near the connecting portion 12. The fact that each locking rib 31 is located on the side of its corresponding fixing rib 111 near the connecting portion 12 means that when the load-bearing member 2 moves towards the connecting portion 12, the locking rib 31 can abut against the adjacent fixing rib 111 located near the connecting portion 12 to achieve locking. Thus, when the load-bearing member 2 moves along the first direction, the load can be simultaneously distributed to the multiple locking ribs 31 and fixing ribs 111. This improves the load-bearing capacity of the integrally manufactured static mechanical non-reciprocal metamaterial unit 100 in the locking direction.

[0067] Please see Figure 4 In some embodiments, the load-bearing member 2 is movably connected to the main support 1 along a first direction via an elastic connector 6. The elastic connector 6 is located between the load-bearing member 2 and the connecting portion 12. The specific geometry of the elastic connector 6 is not limited; any shape capable of achieving elastic support, deformation coordination, load transfer, or reset functions can be applied to the embodiments of this application. For example, an arc-shaped elastic beam, a wave-shaped elastic beam, an S-shaped elastic beam, a closed-loop elastic beam, a frame-shaped elastic beam, or a lattice-shaped elastic structure can be used.

[0068] In this way, when the external load on the load-bearing component 2 disappears, the elastic connector 6 can drive the load-bearing component 2 to automatically reset based on its stored elastic potential energy. As a result, the integrally manufactured static mechanical non-reciprocal metamaterial unit 100 can be capable of responding to cyclic loads.

[0069] Please see Figure 4 In some embodiments, the end of the locking rib 31 away from the load-bearing member 2 has a locking plane 311 and a clearance plane 312. The locking plane 311 is closer to the connecting portion 12 than the clearance plane 312, and there is an angle between the locking plane 311 and the clearance plane 312 (i.e., the shape of the end of the locking rib 31 away from the load-bearing member 2 is asymmetrical). The locking plane 311 refers to the plane on the locking rib 31 that forms contact with the fixed rib 111, and the clearance plane 312 refers to the plane on the locking rib 31 that contacts the fixed rib 111 and guides the rotation of the locking rib 31 when subjected to reverse loading.

[0070] When the loaded member 2 moves a preset distance toward the connecting part 12, the locking rib 31 forms surface contact with the adjacent fixed rib 111 located on its side near the connecting part 12 through the locking plane 311, thus achieving self-locking. The preset distance refers to the displacement required for the loaded member 2 to move from its initial position until the locking rib 31 and the fixed rib 111 form surface contact and self-lock.

[0071] This configuration, by having the locking rib 31 form a surface contact with the adjacent fixing rib 111 located on its side near the connecting portion 12 through the locking plane 311, increases the contact area between the locking rib 31 and the fixing rib 111, avoiding local stress concentration. This, in turn, improves the stability and reliability of the locking state of the integrally manufactured static mechanical non-reciprocal metamaterial unit 100.

[0072] It is understood that the locking rib 31 having a locking plane 311 and a relief plane 312 with an included angle between the locking plane 311 and the relief plane 312 is one example of the cross-sectional shape of the locking rib 31. In other embodiments, the locking rib 31 may also have a locking surface and a relief surface, with the locking surface closer to the connecting portion 12 than the relief surface, and a smooth transition between the locking surface and the relief surface.

[0073] Finally, it is necessary to note that the embodiments of this application are applicable to unidirectional force transfer, directional energy management, vibration damping and buffering, and related non-reciprocal metamaterial structure designs. The integrated static mechanical non-reciprocal metamaterial unit 100 of the embodiments of this application can be integrally formed using single-material or multi-material additive manufacturing methods. Preferably, it can be prepared using a fused deposition modeling process. The manufacturing material can be a polymer material with certain strength and toughness, including but not limited to polylactic acid, thermoplastic polyurethane elastomers, or polyether block amides. As an example, polylactic acid can be used to integrally print the metamaterial unit.

[0074] Of course, this application is not limited thereto. In other embodiments, the integrally manufactured static mechanical non-reciprocal metamaterial unit 100 can be further arranged periodically, arrayed, or partitioned according to the actual application to form a metamaterial array structure or functional component with static mechanical non-reciprocal response.

[0075] Furthermore, it is worth noting that, without departing from the concept of this invention, the specific structural forms of the main support 1, the load-bearing component 2, the elastic connector 6, the locking rib 31, and the hinge 5 can all be adjusted according to actual application needs. The number, length, thickness, inclination angle, tooth profile, and relative arrangement of the locking rib 31 with the load-bearing component 2 can be changed accordingly; the number, position, shape, and contact angle of the stop portions 4 on the load-bearing component 2 can also be optimized according to the positive self-locking requirements.

[0076] The specific structure of the hinge 5 is not limited to the form shown in this embodiment. The dimensions, enclosure form and fitting relationship of the pivot seat 51, pivot 52 and reserved fitting gap can be adjusted according to the printing process accuracy, rotational freedom requirements and structural stability requirements, as long as the locking rib 31 can rotate relative to the load-bearing member 2 and form a low-resistance rotational avoidance when subjected to reverse load.

[0077] To verify the technical effect of the structure of the present invention, a fixed rib structure without hinge 5 (Model 1) was set as a comparative structure (see details). Figure 5 ). Regarding this application Figure 4 The scheme shown (Model 2) and the comparison structure were subjected to quasi-static compression / tension tests. During the test, the sample was installed in a quasi-static loading device, and a positive compressive load and a negative tensile load were applied to the loaded component 2 along the axial direction. The load response under different displacements was recorded, and the results were obtained as follows: Figure 6 The diagram shows a comparison of force-displacement curves in both positive and negative directions.

[0078] Please see Figure 6 , Figure 6 for Figure 5 The structure shown is Figure 4 The diagram shows a comparison of force-displacement curves for the structure under positive and negative forces. Under positive force conditions, Model 2 (of this application) Figure 4 In the scheme shown, the first locking rib 31a rotates slightly under the action of the hinge 5 and gradually contacts the stop part 4 on the load-bearing member 2, forming a contact self-locking, thereby establishing an effective load-bearing path.

[0079] Under reverse force conditions, Model 2 (of this application) Figure 4 In the scheme shown, the locking rib 31 rotates around the first axis A1 to form a rotational clearance, keeping the reverse force at a low level. In contrast, the scheme of the comparative structure (model 1) mainly relies on the coordinated deformation of the fixed rib, the main support 1 and the elastic element to achieve clearance when subjected to reverse load, thus the reverse resistance is larger.

[0080] Based on the results of forward and reverse testing, the non-reciprocity ratio of the structure can be further calculated to characterize the differences in the mechanical response of the structure under different loading directions. (See details...) Figure 7 , Figure 7 for Figure 5 The structure shown is Figure 4 A comparison curve showing the non-reciprocity ratio of the structure shown as a function of displacement. Model 2 (This application) Figure 4 Compared to the comparative structure (Model 1), the scheme shown has significantly reduced reverse resistance and a significantly improved non-reciprocal ratio. This demonstrates that rotatably connecting the locking rib 31 to the load-bearing member 2 via the hinge 5 effectively enhances the static mechanical non-reciprocal response of the structure.

[0081] Please see Figure 8 , Figure 8 for Figure 5 The structure shown is Figure 4 The diagram shows a comparison of the positive force-displacement curves for the structure shown. For model 2 (of this application) Figure 4 A separate comparison of the positive force-displacement curves of the scheme shown in the application and the comparison structure shows that Model 2 (in this application) Figure 4 The scheme shown maintains a high positive load-bearing capacity throughout its entire working stroke. Although its equivalent stiffness in the initial to middle stage of positive compression is lower than that of the comparative structure (mainly due to the rotational adjustment of the locking rib 31 before and after contact establishment and the closing process of the fitting gap), after the locking rib 31 and the stop part 4 are in full contact and form a stable self-locking, Model 2 (of this application) Figure 4 The scheme shown can still maintain a high level of positive load-bearing capacity. Therefore, it can be seen that the effect of making the locking rib 31 rotatably connected to the load-bearing member 2 via the hinge 5 on the final positive load-bearing capacity is small.

[0082] In summary, by rotatably connecting the locking rib 31 to the load-bearing member 2 via the hinge 5, this application effectively reduces the reverse resistance and improves the static mechanical non-reciprocal response without significantly weakening the positive load-bearing capacity of the structure.

[0083] To optimize the structural parameters of hinge 5, comparative analysis was conducted on samples under different reserved fit clearances (the difference between the radius of the aforementioned rotating hole 521 and the radius of the rotating column 512, and the difference between the minimum distance between the two rotating columns 512 and the minimum distance between the two rotating holes 521). Preferably, by comparing the forming state, rotation function, and mechanical response of the samples under different clearance conditions, the reasonable reserved fit clearance range of hinge 5 was determined.

[0084] Please see Figure 9 , Figure 9 The positive force-displacement comparison curves are shown for hinge 5 with reserved gaps of 1 mm and 1.2 mm. Positive compression tests were conducted on samples with reserved gaps of 1 mm and 1.2 mm. Their positive force-displacement curves were generally similar, indicating that within this range, the change in the reserved gap has little impact on the positive load-bearing capacity of the structure.

[0085] In addition, it is necessary to point out that although the difference between the samples with reserved fitting clearance of 1 mm and 1.2 mm on the positive force-displacement curve is not significant, when the reserved fitting clearance is 1.2 mm, the sample exhibits the phenomenon of pivot 52 partially dislodging from pivot seat 51 after positive compression. This indicates that an excessively large reserved fitting clearance will cause the fit between pivot 52 and pivot seat 51 to become loose, which is not conducive to structural stability and reusability.

[0086] When the reserved fitting clearance is 0.4 mm, the locking rib 31 can still rotate normally through the hinge 5; however, when the reserved fitting clearance is reduced to 0.2 mm, the hinge 5 can hardly rotate normally, indicating that if the reserved fitting clearance is too small, it will be affected by printing accuracy and local adhesion, which is not conducive to the realization of the function of the hinge 5.

[0087] In summary, the reserved fitting clearance of hinge 5 should be neither too large nor too small. An excessively large clearance will cause hinge 5 to loosen and affect structural stability; an excessively small clearance will affect the rotational function after printing. Preferably, the reserved fitting clearance is set to 0.4 mm to 1 mm to balance printability, rotational freedom, and structural stability.

[0088] To further verify Figure 4 The reusability stability of hinge 5 in the illustrated scheme was tested by manually bending the sample 500 times, followed by testing its positive force-displacement response, as shown below. Figure 10 The diagram shows a comparison of the force-displacement curves of hinge 5 after 500 bends and when it is not bent.

[0089] The positive force-displacement curves of the sample after 500 manual bends are generally similar to those of the unbent sample, indicating that the integrated printed hinge 5 can still maintain relatively stable positive load-bearing performance under the condition of repeated manual bending, and has a certain degree of stability for repeated use. The above results show that the structure has preliminary durability, but does not constitute a standard fatigue life test conclusion.

[0090] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A statically non-reciprocal metamaterial unit manufactured in one piece, characterized in that, include: The main support includes a fixing part, on which a plurality of fixing ribs are arranged at intervals along a first direction; A load-bearing component, which is spaced apart from the fixing part in a second direction and movably connected to the main body support along the first direction; wherein the second direction is perpendicular to the first direction; At least one locking rib, one end of each locking rib being rotatably connected to the load-bearing member about a first axis; the first axis being perpendicular to both the first direction and the second direction; the at least one locking rib includes a first locking rib, one end of the first locking rib being located away from the load-bearing member between two adjacent fixed ribs; At least one stop portion, each of the stop portions being disposed on the load-bearing member; each of the locking ribs corresponds to one stop portion, and each stop portion is located on the side of its corresponding locking rib closer to the load source, so as to restrict the rotation of its corresponding locking rib; in the unloaded state of the load-bearing member, the distance between the stop portion along the second direction and the fixed rib located on its side closer to the load source and adjacent to it is greater than or equal to zero.

2. The integrated, statically non-reciprocal metamaterial unit according to claim 1, characterized in that, The locking rib is rotatably connected to the load-bearing member via a hinge.

3. The integrated, statically non-reciprocal metamaterial unit according to claim 2, characterized in that, The hinge includes a pivot seat and a pivot. The pivot seat is mounted on the load-bearing member and has two plates arranged opposite each other in a third direction. The third direction is parallel to the first axis, and rotating columns are provided on the surfaces of the two plates facing each other. The pivot has rotating holes on both end faces in its own axial direction, and the two rotating holes are inserted into the two rotating columns in a one-to-one correspondence. The locking rib is fixedly connected to the pivot.

4. The integrated, statically non-reciprocal metamaterial unit according to claim 3, characterized in that, The rotating column and its corresponding rotating hole are fitted with a clearance.

5. The integrated, statically non-reciprocal metamaterial unit according to claim 4, characterized in that, On any mating section perpendicular to the first axis, the difference between the radius of the rotating hole and the radius of the rotating column is greater than or equal to 0.4 mm and less than or equal to 1 mm. The difference between the minimum distance between the two rotating columns and the minimum distance between the two rotating holes is greater than or equal to 0.4 mm and less than or equal to 1 mm.

6. The integrated, statically non-reciprocal metamaterial unit according to claim 1, characterized in that, The number of fixing parts is two, and the two fixing parts are arranged at a distance from each other along the second direction and are mirror-symmetrical; the main body support also includes a connecting part, which connects the two fixing parts to the ends away from the load source; The load-bearing component is located between the two fixed parts and on the side of the connecting part closer to the load source; the integrated static mechanical non-reciprocal metamaterial unit also includes two locking rib assemblies, each of which includes at least the first locking rib; the two locking rib assemblies are arranged in a one-to-one correspondence with the two fixed parts.

7. The integrated, statically non-reciprocal metamaterial unit according to claim 6, characterized in that, Along the first direction, the distance between the load-bearing end of the load-bearing member and the connecting portion is greater than the distance between the end of the fixing portion near the load source and the connecting portion.

8. The integrated, statically non-reciprocal metamaterial unit according to claim 6, characterized in that, The locking rib assembly includes a plurality of locking ribs, each of which is corresponding to a plurality of fixing ribs. The end of each locking rib away from the load-bearing member is located on the side of its corresponding fixing rib closer to the connecting portion.

9. The integrated, statically non-reciprocal metamaterial unit according to claim 6, characterized in that, The load-bearing component is movably connected to the main support along the first direction via an elastic connector, the elastic connector being located between the load-bearing component and the connecting portion.

10. The integrated, statically non-reciprocal metamaterial unit according to claim 6, characterized in that, The locking rib has a locking plane and a clearance plane at the end away from the load-bearing member. The locking plane is closer to the connecting part than the clearance plane, and there is an angle between the locking plane and the clearance plane. When the load-bearing member moves to a preset distance toward the connecting part, the locking rib forms a surface contact with the fixed rib located on its side near the connecting part through the locking plane and achieves self-locking.

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