Self-stabilizing closed ring structure with variable diameter

Abstract

The invention discloses a diameter-variable self-stabilizing closed ring structure, and belongs to the technical field of intelligent materials and intelligent structures. The structure includes a flexible linear member forming a continuous closed loop path in a circumferential direction; the flexible linear component is sequentially provided with an inner ring core layer, a radial reinforcing layer and an outer ring elastic base body layer from inside to outside. The radial compression rigidity of the flexible linear component is larger than the circumferential tensile rigidity of the flexible linear component. The inner ring core layer comprises a flow channel filled with shear thickening fluid, the flow channel is alternately provided with widening sections and narrowing sections in the circumferential direction, or is provided with a periodic fluctuating structure, and local impact can be converted into uniform circumferential stress when the flow channel is subjected to radial loads. The problems that an existing variable-diameter ring structure is concentrated in stress and lack of self-centering capacity are solved, and the dual functions of diameter continuous adjustment and self-stability maintaining can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of smart materials and smart structures, specifically relating to a self-stabilizing closed-loop structure with variable diameter. Background Technology

[0002] In modern engineering technology, variable-diameter closed-loop structures have a wide range of applications, such as variable-diameter pipe fittings, flexible clamps, and auxiliary devices for morphological support in medicine. These structures require good geometric stability during diameter adjustment, especially maintaining a perfectly circular cross-section under external loads to ensure reliable system functionality. Existing variable-diameter ring structures mainly employ three technical approaches: first, rigid or semi-rigid segmented structures combined with hinges to achieve size adjustment; second, changing the geometry through local pressing or bending deformation; and third, using non-closed structures that rely on the relative displacement of the free ends to adjust the opening size. The aforementioned solutions generally suffer from the following technical defects in practical applications: First, during the adjustment process, polygonal or non-circular structures are easily formed, resulting in significant stress concentration at hinges or segmented connections, increasing the risk of structural fatigue failure and making it difficult to ensure uniform contact with mating components. Second, the adjustment methods are mostly graded or discrete control, relying on mechanical transmission mechanisms such as gears, pawls, and threads, making it difficult to achieve continuous and smooth diameter changes, and resulting in a large number of parts and high manufacturing and assembly costs. Third, they lack self-centering ability, making it difficult to autonomously restore a circular geometric state under external disturbances or non-uniform loads, resulting in insufficient structural stability. Fourth, the opening of the non-closed structure is prone to deformation under stress, making it difficult to form a stable circumferential stress state. Therefore, there is an urgent need to provide a self-stabilizing closed-loop structure with a simple structure that can maintain a near-circular geometric state throughout the dimensional changes, in order to solve the technical problems of stress concentration and lack of self-centering ability in the existing technology. Summary of the Invention

[0003] The present invention aims to provide a closed-loop structure with anisotropic stiffness characteristics. By making the radial compressive stiffness of the flexible linear component greater than the circumferential tensile stiffness, it simultaneously possesses the ability to smoothly change diameter and resist local deformation, thus overcoming the contradiction between diameter adjustment and shape maintenance in traditional closed-loop structures.

[0004] The present invention adopts the following technical solution: A variable-diameter self-stabilizing closed-loop structure includes a flexible linear member forming a continuous closed-loop path along the circumference. The flexible linear member comprises an inner core layer, a radial reinforcement layer, and an outer elastic matrix layer arranged sequentially from the inside out. The radial reinforcement layer contains at least two reinforcement units discontinuously distributed along the circumference. The flexible linear member is constructed such that its radial compressive stiffness is greater than its circumferential tensile stiffness. This invention, through the discontinuous distribution of reinforcement units, enables the flexible linear member to exhibit differentiated mechanical response characteristics in the radial and circumferential directions, constructing it with an anisotropic mechanical characteristic of "radial compressive stiffness greater than circumferential tensile stiffness," thus overcoming the contradiction between diameter adjustment and shape maintenance in traditional closed-loop structures. When a diameter change is required, the smaller circumferential tensile stiffness allows the ring to achieve a smooth diameter change with lower driving force; when subjected to local radial loads, the larger radial compressive stiffness enables the ring to effectively resist local deformation. This anisotropic stiffness design gives the closed-loop structure both good diameter-changing flexibility and load-bearing stability.

[0005] Furthermore, the circumferential elastic modulus of the inner core layer is lower than that of the outer elastic matrix layer. When the flexible linear member is subjected to uneven radial outward load, the inner core layer absorbs local strain by preferentially undergoing circumferential tensile deformation, while the outer elastic matrix layer provides circumferential constraint and restoring force, causing the closed loop path to automatically recover to a smooth circle.

[0006] Preferably, the inner core layer includes at least one circumferentially extending flow channel filled with a shear-thickening fluid. The flow channel has alternating widening and narrowing sections along its circumference, causing the cross-sectional gap width of the flow channel to change periodically. When the flexible linear member is subjected to radial load, the shear-thickening fluid in different regions bears the load in either a compression-dominated or shear-dominated mode, amplifying the thickening effect of the shear-thickening fluid in the flow channel geometry. Specifically, when the flexible linear member is subjected to radial load: the shear-thickening fluid in the widening section bears the load in a compression-dominated mode; the shear-thickening fluid in the narrowing section bears the load in a shear-dominated mode; the synergistic effect of the compression-dominated and shear-dominated modes amplifies the thickening effect of the shear-thickening fluid. The synergistic effect of the compression-dominated and shear-dominated modes transforms the local radial load acting on the flexible linear member into a uniformly distributed circumferential stress, ensuring that the closed-loop path maintains uniform expansion upon impact, suppressing local depressions or bulges, thereby maintaining a smooth circular geometry.

[0007] More preferably, the inner core layer comprises an inner flow channel and an outer flow channel arranged coaxially. Both the inner and outer flow channels are filled with a shear-thickening fluid, and the wall of the inner flow channel has a periodic undulating structure. The shear-thickening fluid in the inner and outer flow channels has different particle concentrations, resulting in different shear-thickening trigger thresholds for the inner and outer layers. This achieves a dual-gradient response in the radial direction—the inner flow channel preferentially responds to absorb impact energy, while the outer flow channel subsequently responds to provide structural support, jointly maintaining the circular geometry of the closed-loop path. The periodic undulating structure is distributed in a wave-like pattern along the circumference, forming alternating peak and trough regions. When the flexible linear component is subjected to a radial load, the peak region induces a local increase in shear rate due to the narrowing of the flow channel cross-section, causing the shear-thickening fluid flowing through this region to preferentially trigger shear thickening, forming rigid support points distributed at intervals along the circumference. Specifically, the periodic undulating structure generates a fluid-structure interaction effect with the shear-thickening fluid under radial load. The peaks of the undulating structure induce an increase in local shear rate, causing the shear-thickening fluid to thicken preferentially in this region, forming rigid support points distributed circumferentially. These rigid support points discretize the local impact load acting on the flexible linear member into a uniformly distributed load with multiple support points, thereby suppressing local depressions or bulges and maintaining the circular geometry of the closed loop path.

[0008] This invention provides a diameter-locking self-stabilizing closed-loop structure, suitable for applications requiring a long-term maintenance of the diameter after adjustment to a target value without frequent diameter changes, such as variable-diameter pipes, deployable structure locking mechanisms, and medical device fixation supports. The elastic modulus of the radial reinforcing layer exhibits a gradient distribution along the radial direction, increasing from the side adjacent to the inner core layer to the side adjacent to the outer elastic matrix layer. The outer elastic matrix layer is made of a shape memory alloy capable of phase transformation, used to lock the geometry of the flexible linear component after diameter changes. The inner core layer has a preset circumferential prestress in its natural state, applied by pre-stretching the outer elastic matrix layer during manufacturing. To achieve precise application of the prestress and active diameter adjustment, this solution includes an independently installed radial driving device outside the flexible linear component. The radial driving device comprises multiple driving units spaced circumferentially, with their force-applying ends contacting and engaging with the inner core layer. During the manufacturing and shaping process, the drive unit extends synchronously, applying a uniform radial load to the component, causing the outer elastic matrix layer to produce a preset circumferential elongation and completing the shaping process in this state. After shaping, the drive unit retracts and resets, disengaging from the flexible linear component, thus completing the prestressing process. In daily use, the radial drive device can again cooperate to actively adjust the diameter, and the geometry is locked by the shape memory alloy after adjustment. In the above process, the shear-thickening fluid filled in the inner core layer channel plays an adaptive correction function: when the ring tends to become polygonal, the channel at the polygon vertex narrows, triggering shear thickening and limiting excessive local deformation; when the fluid migrates from the vertex to the midpoint of the edge, the gradient structure of the radial reinforcement layer plays a pressure guiding role. The low-modulus region of the inner layer is easy to deform, allowing the fluid pressure to be smoothly transmitted, while the high-modulus region of the outer layer maintains the overall structural stiffness, ensuring that the pressure transmitted to the midpoint region is converted into an effective radial expansion force, causing the ring to return to a perfect circle.

[0009] This invention also provides a dynamically variable diameter self-stabilizing closed-loop structure, suitable for applications requiring frequent diameter changes and real-time response, such as flexible clamps and adaptive pipelines. The radial reinforcement layer employs a honeycomb telescopic mesh structure, which is composed of at least two interconnected mesh units arranged circumferentially and radially. The mesh units have deformable geometric configurations, including one or more of hexagonal, rhombic, and triangular configurations. Adjacent mesh units share edges or nodes, forming an overall cooperative deformation network. The geometric dimensions and material stiffness of the mesh units remain consistent along the circumference, ensuring that each mesh unit exhibits the same deformation response characteristics during radial expansion and contraction. When the diameter of the closed-loop path changes, all mesh units synchronously generate uniform geometric deformation, resulting in a continuous and uniformly distributed support force field along the circumference of the radial reinforcement layer. The radial support force is smoothly transmitted between the mesh units without local abrupt changes or stress concentration. The honeycomb-type telescopic mesh structure works in synergy with the shear-thickening fluid filled in the inner core layer channel: when the flexible linear component is subjected to local radial impact, the shear-thickening fluid triggers a thickening effect, forming rigid support points distributed circumferentially, discretizing the local impact load into a uniformly distributed load; the honeycomb-type telescopic mesh structure bears the uniformly distributed load through its uniform support stiffness, and further uniformly transfers the load to the entire circumference by utilizing the synchronous deformation of the mesh cells; the instantaneous thickening response of the shear-thickening fluid and the continuous elastic deformation of the honeycomb-type telescopic mesh structure work together to ensure that the closed loop path maintains uniform expansion when subjected to impact, thereby maintaining the near-circular geometry of the closed loop path during the diameter change process.

[0010] The core advantage of this invention lies in its ability to solve the stress concentration problem commonly found in traditional variable-diameter structures through the collaborative design of multi-layered composite structures and smart materials. The key lies in transforming localized loads into uniformly distributed circumferential stresses: when the shear-thickening fluid in the inner channel is impacted, a shear-thickening effect is triggered in the narrowing section, forming rigid support points distributed circumferentially. This discretizes the localized load originally concentrated at the impact point into a uniformly distributed load supported by multiple points, avoiding excessive stress accumulation in a single area. The honeycomb-type telescopic mesh structure further enhances this effect; all mesh elements deform synchronously, allowing stress to be smoothly transmitted along a continuous mesh path without local abrupt changes or stiffness differences, fundamentally eliminating stress concentration points. This stress dispersion and uniform distribution mechanism ensures that the closed-loop structure maintains a near-circular geometry under complex dynamic loads, significantly improving the structure's fatigue life and service reliability.

[0011] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the self-stabilizing closed-loop structure described in Example 1.

[0013] Figure 2 This is a schematic diagram of the deformation state of the self-stabilizing closed-loop structure described in Embodiment 1 under radial load.

[0014] Figure 3 This is a radial cross-sectional schematic diagram of the self-stabilizing closed loop structure in Example 2.

[0015] Figure 4 This is a radial cross-sectional schematic diagram of the self-stabilizing closed loop structure in Example 3.

[0016] Figure 5 This is a schematic diagram of the implementation of the diameter-locking self-stabilizing closed loop structure in Example 4.

[0017] Figure 6 This is a schematic diagram of the dynamic variable diameter self-stabilizing closed loop structure in Example 5.

[0018] Figure descriptions: 1-Inner core layer; 11-Wideened section; 12-Narrowed section; 13-Periodic undulating structure; 2-Radial reinforcement layer; 3-Outer elastic matrix layer; 4-Radial drive device; 5-Honeycomb telescopic mesh structure. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] Example 1 See Figure 1 and Figure 2 A variable-diameter self-stabilizing closed-loop structure includes a flexible linear member forming a continuous closed-loop path along the circumference. The flexible linear member comprises an inner core layer 1, a radial reinforcement layer 2, and an outer elastic matrix layer 3, arranged sequentially from the inside out. The radial reinforcement layer 2 contains at least two reinforcement units discontinuously distributed along the circumference. The flexible linear member is constructed such that its radial compressive stiffness is greater than its circumferential tensile stiffness. This invention, through the discontinuous distribution of reinforcement units, enables the flexible linear member to exhibit differentiated mechanical response characteristics in the radial and circumferential directions, constructing it with an anisotropic mechanical characteristic of "radial compressive stiffness greater than circumferential tensile stiffness," thus overcoming the contradiction between diameter adjustment and shape maintenance in traditional closed-loop structures. When a diameter change is required, the smaller circumferential tensile stiffness allows the ring to achieve a smooth diameter change with lower driving force; when subjected to local radial loads, the larger radial compressive stiffness enables the ring to effectively resist local deformation. This anisotropic stiffness design gives the closed-loop structure both good diameter-changing flexibility and load-bearing stability.

[0022] Furthermore, the circumferential elastic modulus of the inner core layer 1 is lower than that of the outer elastic matrix layer 3. When the flexible linear member is subjected to an uneven radial outward load, the inner core layer 1 absorbs local strain by preferentially undergoing circumferential tensile deformation, while the outer elastic matrix layer 3 provides circumferential constraint and restoring force, causing the closed loop path to automatically recover to a smooth circle.

[0023] Example 2 See Figure 3 In a preferred embodiment of the present invention, the flow channels in the inner core layer 1 are alternately provided with widening sections 11 and narrowing sections 12 along the circumferential direction, so that the cross-sectional gap width of the flow channels changes periodically. The cross-sectional diameter D1 of the widening section 11 is larger than the cross-sectional diameter D2 of the narrowing section 12, and the two are arranged alternately along the circumferential direction to form a series hydraulic chamber-damping throat structure. The flow channels are filled with shear-thickening fluid. Under static or slow diameter change conditions, the shear-thickening fluid maintains a low viscosity state, and the fluid can flow freely between the widening section 11 and the narrowing section 12. The flexible linear component exhibits low circumferential tensile stiffness, which facilitates smooth and continuous adjustment of the diameter.

[0024] When the flexible linear component is subjected to a local radial impact, the widened section 11 near the impact point is compressed first, causing an instantaneous increase in internal fluid pressure and forming a local high-pressure zone. This pressure wave propagates along the flow channel to both sides, much faster than the mechanical deformation rate of the annular material. When the pressure wave propagates to the adjacent narrowed section 12, the fluid is forced to pass through the narrowed throat at high speed. According to the constitutive properties of shear-thickening fluids, when the shear rate of the fluid passing through the narrowed section 12 exceeds a critical threshold, its apparent viscosity increases nonlinearly and sharply, instantly forming a "fluid lock" effect. This effect prevents the rapid release of fluid from the high-pressure zone to the low-pressure zone, enabling the widened section 11 near the impact point to maintain a high pressure gradient, providing a driving force for energy dispersion.

[0025] In the above process, the shear-thickening fluid in the widening section 11 mainly bears the load in a compression-dominated mode—the fluid is compressed, storing pressure energy; the shear-thickening fluid in the narrowing section 12 mainly bears the load in a shear-dominated mode—the fluid flows at high speed, undergoing shear thickening. These two load-bearing modes alternate and work synergistically along the circumference, transforming the single local impact energy into a multi-stage, series-connected compression-shear energy dissipation chain distributed throughout the entire circumference. As the pressure wave propagates continuously along the flow channel and passes through the series structure of multiple widening and narrowing sections, the initial local high pressure is gradually homogenized, eventually leading to a uniform distribution of fluid pressure throughout the entire circumference. Under this uniform pressure field, the ring body experiences a uniformly distributed circumferential tensile stress, driving the ring body to expand uniformly as a whole, rather than experiencing localized depressions or bulges at the impact point.

[0026] After the impact energy dissipates, if the outer elastic matrix layer 3 is in an unlocked state, it releases the stored elastic potential energy, causing the ring to contract radially uniformly and return to its initial perfect circle. If the outer elastic matrix layer 3 is in an unlocked state and is driven by an external load, even if the external load is not uniformly distributed, it can still achieve uniform radial expansion under the action of the external load to reach a new target diameter. If the outer elastic matrix layer 3 is locked by a shape memory alloy, it maintains its current diameter, and the ring maintains its adjusted geometric shape. It can only expand again after the lock is released.

[0027] In summary, through the synergistic effect of the geometric design of the periodic variable gap flow channel and the intelligent rheological properties of the shear thickening fluid, this invention transforms the local radial load acting on the flexible linear component into a uniform circumferential stress distributed along the circumference, so that the closed loop path maintains uniform expansion when subjected to impact, suppresses local depressions or bulges, and thus maintains a smooth circular geometry.

[0028] Example 3 See Figure 4As another preferred embodiment of the present invention, the inner core layer 1 includes an inner flow channel and an outer flow channel arranged coaxially. Both the inner and outer flow channels are filled with a shear thickening fluid, and the wall of the inner flow channel is provided with a periodic undulating structure 13.

[0029] The shear-thickening fluids in the inner and outer flow channels have different particle concentrations. Specifically, the shear-thickening fluid filling the inner flow channel has a lower particle concentration, resulting in a lower critical shear rate, and can preferentially trigger shear thickening under lower impact intensities. The shear-thickening fluid filling the outer flow channel has a higher particle concentration, resulting in a higher critical shear rate, and can only trigger shear thickening under higher impact intensities. This concentration difference forms a radially distributed dual-gradient response mechanism: when the flexible linear component is subjected to radial impact, the inner flow channel responds preferentially, absorbing impact energy through shear thickening; as the impact intensity increases and exceeds a preset threshold, the outer flow channel further triggers shear thickening, providing high-strength structural support. The inner and outer flow channels respond sequentially and work together, ensuring both flexible buffering under low-intensity impacts and rigid protection under high-intensity impacts, enabling the closed-loop path to maintain a smooth circular geometry under various operating conditions.

[0030] The periodic undulating structure 13 on the inner channel wall further enhances the aforementioned gradient protection effect. This periodic undulating structure 13 is circumferentially wave-shaped, with the channel cross-section narrowing at the crests and widening at the troughs, forming a microstructure similar to the widening-narrowing section microstructure described in the previous embodiment. When a radial load is applied to the annulus, the shear-thickening fluid flows within the channel. Upon passing through the crest region of the periodic undulating structure 13, the sudden narrowing of the channel cross-section causes a sharp increase in local velocity, resulting in a significantly higher shear rate in this region compared to the trough region. Based on the constitutive properties of the shear-thickening fluid, the crest region preferentially triggers shear thickening due to the locally high shear rate, instantly forming rigid support points distributed circumferentially. These rigid support points are uniformly distributed along the circumference, discretizing the localized load originally concentrated at the impact point into a uniformly distributed load borne by multiple support points, effectively avoiding stress concentration and localized deformation.

[0031] Taking a diameter change caused by a non-uniform load from the inside out as an example, the working process of this embodiment is as follows: In the initial stage of the diameter change, the lower concentration of shear-thickening fluid in the inner channel preferentially triggers shear thickening in the faster-expanding region, slowing down the excessive expansion in that region; at the same time, the fluid flowing through the peak region of the periodically undulating structure 13 preferentially thickens, forming circumferentially spaced rigid support points, dispersing the local expansion stress to the entire circumference, forcing the slower-expanding region to follow suit synchronously. When the diameter change amplitude further increases, if the local expansion rate exceeds the trigger threshold of the outer channel, the higher concentration of shear-thickening fluid in the outer layer triggers thickening, forming a continuous circumferential support layer. At this time, the discrete support points in the inner layer continue to play the role of uniformly distributing loads, dispersing the local expansion stress to the entire circumference; the continuous support layer in the outer layer provides overall structural stiffness, limiting the upper limit of expansion in each region. The synergistic effect of the inner and outer layers forces the faster-expanding regions to slow down due to the stiffness constraint of the outer layer, while the slower-expanding regions accelerate under the uniform load of the inner layer, thereby making the expansion rates of each region tend to be consistent, and ultimately achieving synchronous and uniform diameter expansion of the ring under non-uniform load.

[0032] Example 4 This embodiment provides a diameter-locking self-stabilizing closed loop structure.

[0033] See Figure 5 The flexible linear component in this embodiment includes an inner core layer 1, a radial reinforcement layer 2, and an outer elastic matrix layer 3 arranged sequentially from the inside out. The elastic modulus of the radial reinforcement layer 2 exhibits a gradient distribution along the radial direction, increasing from the side adjacent to the inner core layer 1 to the side adjacent to the outer elastic matrix layer 3, forming a stiffness gradient that is softer inside and harder outside. This gradient design allows the inner layer to preferentially deform and absorb energy when the ring is subjected to radial loads, while the outer layer provides support and assists in recovery, achieving an optimized balance between energy absorption and structural stiffness.

[0034] The outer elastic matrix layer 3 is made of shape memory alloy, preferably nickel-titanium shape memory alloy. When it is necessary to change the diameter of the closed loop path, the shape memory alloy is heated to enter the austenitic phase, and its superelastic properties allow for diameter adjustment. Once the diameter is adjusted to the target value, it is cooled to the martensitic phase, and the shape memory alloy locks in the current geometric shape, so that the ring can maintain the adjusted diameter for a long time without continuous external energy input. The inner core layer 1 has a preset circumferential prestress in its natural state. This prestress is obtained by pre-stretching the outer elastic matrix layer 3 during the manufacturing process.

[0035] To achieve precise application of prestress and active diameter adjustment, this design includes an independently installed radial drive device 4 on the outside of the flexible linear component. The radial drive device 4 comprises multiple drive units spaced circumferentially, with their force-applying ends contacting the inner core layer 1. During manufacturing and shaping, the drive units extend synchronously, applying a uniform radial load to the component, causing the outer elastic matrix layer 3 to elongate by a predetermined circumferential amount, thus completing the shaping process. After shaping, the drive units retract and reset, disengaging from the flexible linear component, completing the prestress application. In daily use, the radial drive device 4 can again be used to actively adjust the diameter, with the geometry locked by a shape memory alloy after adjustment. In the above process, the shear-thickening fluid filled in the inner core layer 1 plays an adaptive correction function: when the ring tends to become polygonal, the flow channel at the vertex of the polygon narrows, triggering shear thickening and limiting excessive local deformation; when the fluid migrates from the vertex to the midpoint of the edge, the gradient structure of the radial reinforcement layer 2 plays a pressure guiding role. The low-modulus region of the inner layer is easy to deform, so that the fluid pressure is smoothly transmitted, while the high-modulus region of the outer layer maintains the overall structural stiffness, ensuring that the pressure transmitted to the midpoint of the edge is converted into an effective radial expansion force, causing the ring to return to a perfect circle.

[0036] Through the above design, this embodiment achieves the following technical effects: the combination of prestress and the locking function of shape memory alloy enables the ring to maintain the adjusted diameter for a long time without external energy input, significantly reducing the energy consumption of the system; the radial drive device 4 disengages from the flexible linear component after completing the operation, avoiding the influence of the added mass on the dynamic characteristics of the ring; the adaptive correction function of the shear thickening fluid and the gradient stiffness structure work together to automatically maintain the circular geometry of the ring under driving errors or asymmetric loads.

[0037] Example 5 This embodiment provides a dynamically variable diameter self-stabilizing closed loop structure.

[0038] See Figure 6 The radial reinforcement layer 2 adopts a honeycomb telescopic mesh structure 5 to achieve synchronous radial telescopic function. The honeycomb telescopic mesh structure 5 is composed of multiple mesh cells arranged circumferentially and radially and interconnected. Adjacent mesh cells share edges or nodes to form an overall cooperative deformation network.

[0039] In this embodiment, the grid units adopt a hexagonal configuration, forming a periodic arrangement structure similar to a honeycomb. Each side of the hexagonal grid unit is made of an elastic material, which can be integrally molded using the same material as the inner core layer 1 or the outer elastic matrix layer 3, or can be interlocked using independent elastomer materials (such as polyurethane elastomer, silicone rubber, or thermoplastic elastomer). Adjacent hexagonal units share sides, forming a continuous network structure, enabling the entire radial reinforcement layer 2 to deform collaboratively under radial loads.

[0040] When the diameter of the closed-loop path changes, for example, under radially outward expansion force, each hexagonal mesh element undergoes synchronous geometric deformation—the hexagon is stretched radially and correspondingly contracted circumferentially. Since the geometry and material elastic modulus of all mesh elements remain consistent, the deformation of each element during radial expansion and contraction is uniformly distributed, ensuring that the radial reinforcement layer 2 maintains uniform support stiffness along the circumference. This uniform deformation characteristic ensures smooth stress transmission along the continuous mesh path, preventing stress concentration or abrupt stiffness changes in certain local areas, thus effectively maintaining the near-circular geometry of the closed-loop path throughout the diameter change process.

[0041] As a preferred embodiment, the mesh elements can also be rhomboid or triangular in shape. Rhomboid mesh elements, when subjected to radial tension, achieve radial elongation by increasing acute angles and decreasing obtuse angles; triangular mesh elements primarily achieve overall radial deformation through elastic elongation of side lengths and node rotation. Regardless of the geometric configuration, the core design principle is that the geometric dimensions and material stiffness of each mesh element remain consistent along the circumference, ensuring that all elements exhibit the same deformation response characteristics during radial expansion and contraction.

[0042] As a further optimization of this embodiment, the geometric parameters of the mesh element can be designed according to the expected range of diameter variation and load-bearing requirements. Taking a hexagonal mesh as an example, its radial equivalent stiffness... equivalent stiffness in the circumferential direction ratio / The configuration is set to ≥5 to ensure that the radial load-bearing capacity is significantly higher than the circumferential deformation resistance, so that the ring body preferentially undergoes overall diameter change rather than local torsion when subjected to radial loads. The stiffness deviation between adjacent mesh elements is controlled within ≤10% to ensure that the deformation of each element is uniform.

[0043] In this embodiment, the honeycomb telescopic mesh structure 5, combined with the inner core layer 1 and the outer elastic matrix layer 3, forms a complete flexible linear component. Through the design of the honeycomb telescopic mesh structure 5, this embodiment achieves the following beneficial effects: the geometric coupling characteristics of the mesh units enable all units to deform automatically and synchronously, achieving uniform radial expansion and contraction without a complex control system; uniform stress distribution avoids local stress concentration, improving the fatigue life of the structure under cyclic diameter change conditions; by adjusting the geometric parameters and material selection of the mesh units, the radial stiffness characteristics can be flexibly customized to meet the needs of different application scenarios; the honeycomb hollow structure achieves lightweighting while ensuring sufficient support stiffness, reducing the overall weight of the closed-loop structure. Furthermore, due to the excellent load distribution capability of the mesh structure itself, the triggering frequency of shear thickening fluids can be reduced, thereby extending the service life of the closed-loop structure.

[0044] When used in conjunction with an external drive unit, the load applied by the drive unit can be transferred to the honeycomb telescopic mesh structure 5 through the outer elastic matrix layer 3. Each mesh cell deforms synchronously, causing a uniform change in the diameter of the entire closed loop path. The drive unit can provide only local radial outward or radial inward loads. Although the drive unit applies force in only one direction, the geometric coupling characteristics of the honeycomb telescopic mesh structure 5 automatically distribute the local load evenly across the entire circumference, forcing synchronous deformation in each region. Simultaneously, the local thickening and flow migration of the shear-thickening fluid during expansion further assists in ensuring that the expansion rates of each region tend to be consistent. The overall continuity of the outer elastic matrix layer 3 provides a geometric constraint on the deformation, enabling the ring to achieve uniform radial expansion even under unidirectional force. This mechanism maintains the uniformity of the diameter change process, effectively avoids stress concentration, and significantly reduces the complexity and manufacturing cost of the drive system.

[0045] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any way. Any person skilled in the art may make some modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but these should still be regarded as the technology or embodiments that are substantially the same as the present invention.

[0046] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A self-stabilizing closed-loop structure with variable diameter, characterized in that, The system includes a flexible linear member that forms a continuous closed loop path along the circumferential direction; the flexible linear member includes an inner core layer (1), a radial reinforcement layer (2), and an outer elastic matrix layer (3) arranged sequentially from the inside to the outside; wherein the radial reinforcement layer (2) contains at least two reinforcement units that are discontinuously distributed along the circumferential direction; the flexible linear member is constructed such that its radial compressive stiffness is greater than its circumferential tensile stiffness.

2. The variable diameter self-stabilizing closed-loop structure according to claim 1, characterized in that, The inner core layer (1) includes at least one circumferentially extending flow channel filled with a shear-thickening fluid.

3. The variable diameter self-stabilizing closed loop structure according to claim 2, characterized in that, The flow channel is alternately provided with widening section (11) and narrowing section (12) along the circumference, so that the cross-sectional gap width of the flow channel changes periodically; when the flexible linear member is subjected to radial load, the shear thickening fluid in different regions bears the load in compression-dominated or shear-dominated modes respectively, so that the geometry of the flow channel amplifies the thickening effect of the shear thickening fluid.

4. The variable diameter self-stabilizing closed loop structure according to claim 1, characterized in that, The inner core layer (1) includes an inner flow channel and an outer flow channel arranged coaxially. Both the inner and outer flow channels are filled with shear thickening fluid, and the wall of the inner flow channel is provided with a periodic undulating structure (13).

5. The variable diameter self-stabilizing closed loop structure according to claim 4, characterized in that, The periodic undulating structure (13) is distributed in a wave-like pattern along the circumference, forming alternating peak and trough regions. When the flexible linear component is subjected to radial load, the peak region is induced to increase the local shear rate due to the narrowing of the flow channel cross section, causing the shear thickening fluid flowing through the region to preferentially trigger shear thickening, forming rigid support points distributed at intervals along the circumference.

6. The variable diameter self-stabilizing closed-loop structure according to claim 1, characterized in that, The circumferential elastic modulus of the inner core layer (1) is lower than that of the outer elastic matrix layer (3).

7. The variable diameter self-stabilizing closed-loop structure according to claim 1, characterized in that, The elastic modulus of the radial reinforcement layer (2) is distributed in a gradient along the radial direction, and its value increases from the side adjacent to the inner core layer (1) to the side adjacent to the outer elastic matrix layer (3).

8. The variable diameter self-stabilizing closed loop structure according to claim 7, characterized in that, The outer elastic matrix layer (3) is made of a shape memory alloy, which is capable of undergoing a phase transition to lock the geometry of the flexible linear member after the diameter changes.

9. A variable-diameter self-stabilizing closed-loop structure according to claim 8, characterized in that, The inner core layer (1) has a preset circumferential prestress in its natural state. The prestress is applied by pre-stretching the outer elastic matrix layer (3) during the manufacturing process and then shaping it.

10. A variable-diameter self-stabilizing closed-loop structure according to claim 1, characterized in that, The radial reinforcement layer (2) includes a honeycomb telescopic mesh structure (5), which is composed of at least two mesh units arranged in the circumferential and radial directions connected to each other; the mesh unit is a deformable geometric configuration, including one or more of hexagonal, rhomboid, and triangular configurations; adjacent mesh units share edges or nodes to form an overall cooperative deformation network.

Images