Preloaded tunable torsional quasi-zero stiffness isolator for cantilever structures
By designing a preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures, and utilizing the parallel structure of positive and negative stiffness components, a quasi-zero stiffness characteristic with dynamic stiffness approaching zero is achieved in the cantilever structure. This resolves the contradiction between low-frequency vibration isolation and adjustable load-bearing capacity, and realizes efficient low-frequency vibration isolation and high torque load-bearing capacity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIHANG UNIV
- Filing Date
- 2026-05-28
- Publication Date
- 2026-07-24
AI Technical Summary
In the existing technology, there is a contradiction between low-frequency vibration isolation and the static load-bearing stiffness of the system in traditional linear vibration isolation systems, and there is a lack of adjustable torsional quasi-zero stiffness vibration isolators suitable for cantilever structures, making it difficult to balance low-frequency vibration isolation and load-bearing adjustable capability.
A preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures was designed. By connecting positive stiffness components and negative stiffness components in parallel and adjusting the rotation angle of the fixed outer ring and the adjustable outer ring using movable connectors, a quasi-zero stiffness characteristic with dynamic stiffness approaching zero can be achieved. The outer ring rotation angle can be adjusted to adapt to different load conditions.
While maintaining high load-bearing capacity, it effectively isolates low-frequency and even ultra-low-frequency angular fluctuations, broadens the vibration isolation load range, and solves the problem of traditional torsional vibration isolators being unable to balance low-frequency vibration isolation and adjustable load-bearing capacity.
Smart Images
Figure CN122447449A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vibration isolator technology, and more specifically to a preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures. Background Technology
[0002] Vibration isolation is a key technology for ensuring the performance of precision equipment, improving structural reliability, and achieving vibration isolation of cantilever structures. Traditional linear vibration isolation systems perform well in isolating high-frequency vibrations, but there is an inherent contradiction between their low-frequency isolation performance and the system's static load-bearing stiffness: to obtain a lower initial isolation frequency, the system stiffness needs to be reduced, but this weakens the support stability. Quasi-zero stiffness isolators, through nonlinear structural design, achieve extremely low dynamic stiffness near the equilibrium position while maintaining high static stiffness, thus providing an ideal solution for low-frequency and even ultra-low-frequency vibration isolation. In addition, traditional linear passive vibration isolation requires reducing the load-bearing stiffness of the structure, while nonlinear passive vibration isolation has greater static stiffness and lower dynamic stiffness, combining dynamic vibration isolation and static load-bearing capacity. Currently, existing quasi-zero stiffness isolators mainly focus on quasi-zero stiffness isolation schemes for isolating linear vibrations, while isolation schemes for torsional vibrations are relatively few. In other words, while quasi-zero stiffness isolators for linear vibrations have become more diversified and high-performance, torsional quasi-zero stiffness isolation devices that can be directly applied to engineering practice and have good adjustability and stability remain scarce. This highlights the urgency and importance of developing an integrated, adjustable, dedicated torsional vibration isolator.
[0003] Therefore, it is necessary to develop and design a preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures. Achieving continuous adjustment of the required preload while realizing quasi-zero stiffness torsional response is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0004] To address the aforementioned problems, this invention provides a preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures, which achieves continuous adjustment of the required preload while realizing a torsional response with quasi-zero stiffness.
[0005] To achieve the above objectives, the present invention provides the following solution: This invention discloses a preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures, comprising a torsional quasi-zero stiffness module, a cantilever structure, and a cantilever structure support base fixedly connected to the cantilever structure. The torsional quasi-zero stiffness module is provided on both sides of the cantilever structure and the cantilever structure support base, with at least one module on each side. Each torsional quasi-zero stiffness module includes a positive stiffness component and a negative stiffness component exhibiting negative stiffness characteristics. The positive stiffness component includes a fixed outer ring and a positive stiffness element. The system includes an inner ring and a pre-formed compliant beam for connecting the fixed outer ring and the positive stiffness component connecting inner ring. The negative stiffness component includes an adjustable outer ring, a negative stiffness component connecting inner ring, and a compression buckling beam for connecting the adjustable outer ring and the negative stiffness component connecting inner ring. The positive stiffness component connecting inner ring and the negative stiffness component connecting inner ring are fixedly connected by a connector, and the fixed outer ring and the adjustable outer ring are connected by a movable connector to achieve angular adjustment of the fixed outer ring and the adjustable outer ring.
[0006] Preferably, a second arc-shaped connector is provided on both sides of the cantilever structure support base, and the arc of the second arc-shaped connector is consistent with the arc of the adjustable outer ring.
[0007] Preferably, the cantilever structure includes a cantilever beam clamping support, a cantilever beam disposed on the cantilever beam clamping support, and a cantilever beam connector for connecting the cantilever beam clamping support and the cantilever beam. Connecting members are provided on both sides of the cantilever beam clamping support. The connecting members are connected to the inner ring of the positive stiffness component and the inner ring of the negative stiffness component. The top of the cantilever structure support base is fixedly connected to the cantilever beam clamping support, and both sides of the cantilever beam clamping support are fixedly connected to the adjustable outer ring.
[0008] Preferably, the cantilever beam connector includes a clamping plate for clamping the cantilever beam and clamping screws that pass through the clamping plate, the cantilever beam, and the cantilever beam clamping support in sequence.
[0009] Preferably, the movable connector includes a waist-shaped hole on the adjustable outer ring, a threaded hole on the fixed outer ring, and a connecting screw for connecting the waist-shaped hole and the threaded hole.
[0010] Preferably, the connector includes a square hole formed in the inner ring connecting the negative stiffness component and the inner ring connecting the positive stiffness component, and a square shaft for connecting the square hole.
[0011] Preferably, a bearing support component is provided between the positive stiffness component and the negative stiffness component. The bearing support component includes a square shaft adapter ring connected to the square shaft, a bearing sleeved on the outer periphery of the square shaft adapter ring, a bearing support member provided on the outer periphery of the bearing, and a first arc-shaped connector provided at the end of the bearing support member away from the square shaft adapter ring. The fixed outer ring, the adjustable outer ring, and the first arc-shaped connector are connected by the connecting screw.
[0012] Preferably, an interlayer support ring is provided between the fixed outer ring and the adjustable outer ring. The interlayer support ring is disposed on the fixed outer ring, and a through hole communicating with the threaded hole is provided on the interlayer support ring.
[0013] Preferably, at least three first T-shaped snap-fit grooves are provided circumferentially on both the adjustable outer ring and the inner ring connecting the negative stiffness component, and the two ends of the compression buckling beam are provided with first T-shaped connectors that snap into the first T-shaped snap-fit grooves. The length of the compression buckling beam is less than the distance from the outer wall of the inner ring connecting the negative stiffness component to the inner wall of the adjustable outer ring.
[0014] Preferably, at least three second T-shaped snap-fit grooves are provided on the circumferential direction of both the fixed outer ring and the inner ring connecting the positive stiffness component, and the two ends of the preformed compliant beam are provided with second T-shaped connectors that snap into the second T-shaped snap-fit grooves. The length of the compliant beam is equal to the distance from the outer wall of the inner ring connecting the positive stiffness component to the inner wall of the fixed outer ring.
[0015] The present invention achieves the following technical effects compared to the prior art: By connecting the pre-formed compliant beam in the positive stiffness component and the compression buckling beam in the negative stiffness component in parallel, and adjusting the rotation angle of the fixed outer ring and the adjustable outer ring using movable connectors, a near-zero stiffness characteristic with dynamic stiffness approaching zero can be achieved near the equilibrium position. This allows the system to maintain high load-bearing capacity when subjected to large static torques, while efficiently isolating low-frequency and even ultra-low-frequency rotational fluctuations during dynamic torsional vibrations. Furthermore, by adjusting the rotation angle of the outer ring, the pre-compression degree of the positive stiffness component can be flexibly changed, enabling the system's near-zero stiffness range to adapt to different load conditions, thus broadening the effective vibration isolation load range and solving the problem of traditional torsional vibration isolators struggling to balance low-frequency vibration isolation with adjustable load-bearing capacity. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Appendix Figure 1 This is a schematic diagram of the overall structure of the torsional quasi-zero stiffness module disclosed in this invention; Appendix Figure 2 This is an exploded view of the torsional quasi-zero stiffness module disclosed in this invention. Appendix Figure 3 This is a schematic diagram of the torsional quasi-zero stiffness modular compression buckling beam and preformed compliant beam structure disclosed in this invention; Appendix Figure 4 The corresponding attachment in the negative stiffness component of the torsional quasi-zero stiffness module disclosed in this invention Figure 9 A schematic diagram of the structure at the stable equilibrium point of point A in the middle; Appendix Figure 5 The corresponding attachment in the negative stiffness component of the torsional quasi-zero stiffness module disclosed in this invention Figure 9 A schematic diagram of the structure at point B, the unstable equilibrium point. Appendix Figure 6 The corresponding attachment in the negative stiffness component of the torsional quasi-zero stiffness module disclosed in this invention Figure 9 A schematic diagram of the structure at point C, when it is in an unstable equilibrium state. Appendix Figure 7 The corresponding attachment in the negative stiffness component of the torsional quasi-zero stiffness module disclosed in this invention Figure 9 A schematic diagram of the structure at the stable equilibrium point of point D; Appendix Figure 8 This is a schematic diagram of the positive stiffness component structure in the torsional quasi-zero stiffness module disclosed in this invention; Appendix Figure 9 This is a schematic diagram showing the torque-rotation relationship between the positive stiffness component and the negative stiffness component in the torsional quasi-zero stiffness module disclosed in this invention. Appendix Figure 10 This is a schematic diagram of the bearing support component structure in the torsional quasi-zero stiffness module disclosed in this invention; Appendix Figure 11 The torsional quasi-zero stiffness module disclosed in this invention has adjustable quasi-zero stiffness response characteristics when the negative stiffness component is in the upper branch; Appendix Figure 12 The torsional quasi-zero stiffness module disclosed in this invention provides adjustable quasi-zero stiffness response characteristics when the negative stiffness component is in the lower branch. Appendix Figure 13 This is a schematic diagram of the overall structure of the preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures disclosed in this invention. Appendix Figure 14 This is an exploded view of the preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures disclosed in this invention. Appendix Figure 15This is a schematic diagram of the overall structure of the preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures, which is disclosed in this invention and consists of multiple quasi-zero stiffness modules connected in series. Appendix Figure 16 This is a diagram showing the relationship between the multi-stage preload quasi-zero stiffness torque and rotation angle of the preload adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures disclosed in this invention. Among them, 1. Negative stiffness component; 10. Adjustable outer ring; 11. Compression buckling beam; 12. Negative stiffness component connecting inner ring; 13. Connecting nut; 2. Positive stiffness component; 20. Fixed outer ring; 21. Preformed compliant beam; 22. Positive stiffness component connecting inner ring; 23. Connecting screw; 3. Bearing support component; 30. Bearing; 31. Square shaft adapter ring; 32. Bearing support component; 33. Interlayer support ring; 34. Inner ring interlayer support ring; 5. Cantilever structure; 50. Cantilever beam clamping support; 51. Clamping plate; 52. Clamping screw; 53. Cantilever beam; 6. Cantilever structure support base; 60. Base body; 61. Fixed nut. Detailed Implementation
[0018] 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.
[0019] The purpose of this invention is to provide a preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures, which achieves continuous adjustment of the required preload while realizing a torsional response with quasi-zero stiffness.
[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0021] refer to Figures 1-16The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures disclosed in this embodiment of the invention includes a torsional quasi-zero stiffness module, a cantilever structure 5, and a cantilever structure support base 6 fixedly connected to the cantilever structure 5. Both sides of the cantilever structure 5 and the cantilever structure support base 6 are provided with torsional quasi-zero stiffness modules. At least one torsional quasi-zero stiffness module is provided on each side, and each module includes at least a positive stiffness component 2 and a negative stiffness component 1 exhibiting negative stiffness characteristics. The positive stiffness component 2 and the negative stiffness component 1 can be combined to form a quasi-zero stiffness member. The positive stiffness component 2 includes a fixed outer ring 20, and a positive stiffness component connecting inner ring 22 is concentrically arranged inside the fixed outer ring 20. The fixed outer ring 20 and the positive stiffness component connecting inner ring 22 are connected by a pre-formed compliant curved beam 21. The negative stiffness component 1 includes an adjustable outer ring 10, and a negative stiffness component connecting inner ring 12 is concentrically arranged inside the adjustable outer ring 10. The adjustable outer ring 10 and the negative stiffness component connecting inner ring 12 are connected by a compression buckling beam 11. The positive stiffness component connecting inner ring 22 and the negative stiffness component connecting inner ring 12 are fixedly connected by a connector, and the fixed outer ring 20 and the adjustable outer ring 10 are connected by a movable connector, thereby realizing the angle adjustment of the fixed outer ring 20 and the adjustable outer ring 10. By connecting the pre-formed compliant curved beam 21 in the positive stiffness component 2 and the compression buckling beam 11 in the negative stiffness component 1 in parallel, and using the movable connector to adjust the angle of the fixed outer ring 20 and the adjustable outer ring 10, a quasi-zero stiffness characteristic with dynamic stiffness approaching zero can be achieved near the equilibrium position. This maintains high load-bearing capacity when subjected to large static torque, while efficiently isolating low-frequency and even ultra-low-frequency angle fluctuations in dynamic torsional vibration. Moreover, by adjusting the outer ring angle, the pre-compression degree of the positive stiffness component 2 can be flexibly changed, so that the quasi-zero stiffness range of the system can adapt to different load conditions, broadening the effective vibration isolation load range and solving the problem that traditional torsional vibration isolators cannot balance low-frequency vibration isolation and load-bearing adjustable capacity.
[0022] refer to Figures 4-9 It should be noted that positive stiffness component 2 exhibits positive stiffness characteristics, while negative stiffness component 1 exhibits negative stiffness characteristics. This ensures that the combination of positive stiffness component 2 and negative stiffness component 1 results in quasi-zero stiffness characteristics. Positive stiffness component 2 consistently exhibits positive stiffness characteristics, and its rotation-moment relationship is linear. Negative stiffness component 1's rotation-moment relationship exhibits hysteretic bistable characteristics, meaning it has an upper and lower branch. Each branch has a stable equilibrium point and an unstable equilibrium point. The two branches switch when the rotation angle reaches a critical threshold, resulting in a structural jump. Preloading is applied to negative stiffness component 1, moving it from the stable equilibrium point to the unstable equilibrium point. It exhibits negative stiffness characteristics near the unstable equilibrium point. The upper branch has a stable equilibrium point (point A), an upper branch has an unstable equilibrium point (point B), and the lower branch has a stable equilibrium point (point C) and an lower branch has an unstable equilibrium point (point D). (This is in conjunction with the attached...) Figure 9It can ensure that the negative stiffness component 1 exhibits negative stiffness characteristics, and when the negative stiffness component 1 is at an unstable equilibrium point, its compression buckling beam 11 is centrally symmetrically arranged.
[0023] refer to Figures 1-3 In one embodiment, the movable connector includes an oblong hole on the adjustable outer ring 10, a threaded hole on the fixed outer ring 20, and a connecting screw 23 for connecting the oblong hole and the threaded hole. By simply loosening the screw, the adjustable outer ring 10 can be continuously adjusted relative to the fixed outer ring 20 along the guide range of the oblong hole. After adjustment, tightening the screw can achieve reliable locking. Thus, continuous preload adjustment of the relative stable points of the positive and negative stiffness components 1 is achieved with extremely low cost and simple operation. At the same time, the length of the oblong hole limits the adjustment range, which can prevent over-adjustment from causing structural instability or damage. Furthermore, the screw connection method facilitates on-site disassembly and maintenance, and can meet the stiffness matching requirements under different working conditions without the need for a complex transmission mechanism. This significantly improves the convenience, safety, and engineering practicality of the vibration isolator preload adjustment.
[0024] It should be noted that the oblong holes are evenly distributed along the circumference of the adjustable outer ring 10, and the oblong holes have a stepped structure. A connecting nut 13, which can slide within the oblong hole, is also provided inside. The connecting screw 23 is connected to the connecting nut 13. The width of the stepped oblong hole is designed so that the connecting nut 13 can be sunk into it and its rotational freedom is constrained. On the one hand, this achieves smooth and continuous angle adjustment under the synchronous guidance of multiple screws, ensuring the uniformity and consistency of preload adjustment. On the other hand, the stepped structure allows the connecting nut 13 to be completely sunk into the oblong hole, precisely constraining the rotational freedom of the nut using the width of the oblong hole. Therefore, when tightening the connecting screw 23, no additional tools are needed to fix the nut 61, greatly simplifying the operation. At the same time, the sunk design prevents the nut from protruding from the outer ring surface, effectively reducing the radial dimension of the vibration isolator and preventing interference between the nut and the external structure, making the overall structure more compact and reliable, and facilitating installation and maintenance in limited spaces such as the cantilever structure 5.
[0025] refer to Figures 11-12 As one implementation method, the relative angle θ0 between the adjustable outer ring and the fixed outer ring 20 is manually rotated (to accommodate the angle). Figure 11 and attached Figure 12 Based on the torque corresponding to θ0 in the figure, the adjustment is carried out. After adjusting to the appropriate angle, an appropriate preload is applied to the connecting screw 23 so that the friction of the connecting nut 13 completely constrains the adjustable angle outer ring. In order to increase the friction, anti-slip patterns can be designed on the contact surface between the adjustable angle outer ring, the cantilever structure support base 6, and the connecting nut 13 to increase the friction.
[0026] refer to Figures 1-3In one implementation, the connector includes square holes formed on the inner ring 12 of the negative stiffness component and the inner ring 22 of the positive stiffness component, and a square shaft for connecting the square holes. By utilizing the mating characteristics of the square shaft and the square holes, a fixed connection without relative rotation is achieved between the inner rings of the negative stiffness component 1 and the positive stiffness component 2, ensuring that the two maintain the same rotation angle during torsion, thereby guaranteeing the precise parallel superposition of positive and negative stiffness. On the other hand, the square shaft connection structure has the advantages of large torque bearing capacity, no slippage, and no clearance, which can effectively transmit the torsional load generated at the root of the cantilever structure 5, avoiding the loosening or clearance errors that may occur with traditional key connections or screw connections, and improving the stability and reliability of the quasi-zero stiffness characteristics. In addition, the mating method of the square shaft and the square holes facilitates assembly and disassembly, which is conducive to modular replacement and maintenance.
[0027] refer to Figure 10 As a preferred embodiment, a bearing support component 3 is provided between the positive stiffness component 2 and the negative stiffness component 1. The bearing support component 3 includes a square shaft connection adapter, with the square shaft sequentially passing through the positive stiffness component 2, the square shaft adapter ring 31, and the positive stiffness component 2, connecting the three together. A bearing 30 is fitted on the outer circumference of the square shaft adapter ring 31, and a bearing support component 32 is fitted on the outer circumference of the bearing 30. A first arc-shaped connector is provided at the end of the bearing support component 32 away from the square shaft adapter ring 31. The fixed outer ring 20, the adjustable outer ring 10, and the first arc-shaped connector are connected by connecting screws 23, realizing torsional bearing... The decoupling of the load and radial load allows the positive and negative stiffness components 1 to primarily bear the torsional load and achieve quasi-zero stiffness characteristics, while the bearing support component 3 independently bears the radial shear force and bending moment transmitted by the cantilever structure 5. This avoids the radial load from generating additional stress or torsional deformation on the flexible beam, ensuring that the positive and negative stiffness components 1 operate only in pure torsional conditions, thereby improving the accuracy and stability of the quasi-zero stiffness characteristics. At the same time, this compact interlayer integrated structure effectively utilizes the axial space, making the overall rigidity and flexibility of the vibration isolator distinct and the force path clear, which is beneficial to improving the reliability and service life of the vibration isolator under large loads or complex working conditions.
[0028] It should be noted that the curvature of the first arc-shaped connector is consistent with that of the fixed outer ring 20 and the adjustable outer ring 10. During assembly, the three can fit together seamlessly, forming a uniform and continuous cylindrical or annular surface contact. This results in a uniform radial preload after tightening with the connecting screws 23, avoiding local stress concentration or contact gaps caused by curvature mismatch, and significantly improving the connection stiffness and coaxiality of the overall structure. On the other hand, the consistent curvature design ensures that the fixed outer ring 20, the adjustable outer ring 10, and the first arc-shaped connector can deform in tandem under temperature changes or vibration environments, reducing additional internal stress caused by differences in thermal expansion coefficients or uneven stress, thereby ensuring the stability and reliability of the quasi-zero stiffness characteristics of the vibration isolator during long-term use. In addition, the consistent curvature also facilitates the processing and assembly of parts, reducing manufacturing and alignment difficulties.
[0029] refer to Figures 1-3 As a preferred embodiment, an interlayer support ring 33 is provided between the fixed outer ring 20 and the adjustable outer ring 10. The interlayer support ring 33 is mounted on the fixed outer ring 20 and has a through hole communicating with the threaded hole. The axial height of the interlayer support ring 33 precisely maintains the designed spacing between the fixed outer ring 20 and the adjustable outer ring 10, ensuring that the positive stiffness component 2 and the negative stiffness component 1 are in the correct working position in the axial direction, avoiding axial displacement or additional deformation of the flexible beam caused by assembly errors or overtightening of the connecting screws 23. On the other hand, the through hole on the interlayer support ring 33 and the fixed outer ring 20 The threaded hole and the oblong hole of the adjustable outer ring 10 work together to provide a continuous and unobstructed through channel for the connecting screw 23, allowing the screw to reliably pass through the adjustable outer ring 10 and the interlayer support ring 33 in sequence before being threadedly connected to the fixed outer ring 20. This ensures the overall tightness and coaxiality of the multi-layer structure while achieving the rotation adjustment function. In addition, the interlayer support ring 33, as an independent load-bearing component, can withstand the preload generated by the connecting screw 23 and evenly transmit it to the fixed outer ring 20, avoiding the fixed outer ring 20 from directly bearing concentrated loads and causing local deformation, thus improving the structural stability and service life of the vibration isolator.
[0030] refer to Figures 1-3As one implementation method, at least three first T-shaped snap-fit grooves are provided circumferentially on both the adjustable outer ring 10 and the inner ring 12 connecting the negative stiffness component. The two ends of the compression buckling beam 11 are provided with first T-shaped connectors that snap into the first T-shaped snap-fit grooves. The length of the compression buckling beam 11 is less than the distance from the outer wall of the inner ring 12 connecting the negative stiffness component to the inner wall of the adjustable outer ring 10, achieving uniform circumferential arrangement and quick detachable installation of multiple buckling beams. Simultaneously, the original length of the beam is designed to be less than the radius difference between the inner and outer rings, thus requiring axial compression of the beam during assembly before it can be inserted into the snap-fit grooves. This pre-compression assembly method... The buckling beam stores elastic potential energy in its initial state and is near the critical buckling state, which facilitates rapid entry into the negative stiffness working zone during torsion. The T-shaped snap-fit structure can not only effectively transmit torque and prevent the beam from coming out of the slot under load, but also ensure the consistency of response of the negative stiffness component 1 in different torsional directions due to the symmetrical arrangement of at least three beams, avoiding the generation of eccentric loads. In addition, the snap-fit connection method facilitates the rapid replacement of compression buckling beams 11 with different cross-sections or material parameters according to different working conditions to achieve the required negative stiffness characteristics, which significantly improves the modularity and engineering adaptability of the vibration isolator.
[0031] refer to Figures 1-3 As one implementation method, at least three second T-shaped snap-fit slots are provided circumferentially on both the fixed outer ring 20 and the inner ring 22 connecting the positive stiffness component. The two ends of the preformed compliant beam 21 are provided with second T-shaped connectors that snap into the second T-shaped snap-fit slots. The length of the preformed compliant beam 21 is equal to the distance from the outer wall of the inner ring 22 connecting the positive stiffness component to the inner wall of the fixed outer ring 20, achieving a circumferentially symmetrical layout and quick detachable installation of multiple preformed compliant beams 21. The original length of the preformed compliant beam 21 is designed to be precisely equal to the radius difference between the inner and outer rings, allowing the beam to be naturally inserted into the snap-fit slots without pre-compression during assembly. At this time, the beam is in the pre-bent shape given by the design, possessing a definite... The positive stiffness characteristics; the T-shaped snap-fit structure ensures that the beam can reliably transmit force and torque when subjected to torsional loads, preventing disengagement or relative slippage during positive stiffness operation; the symmetrical arrangement of at least three beams ensures that the stiffness response of the positive stiffness component 2 is uniform and consistent in different torsional directions, avoiding instability caused by eccentric torque; in addition, the snap-fit connection combined with the precise design of the beam length makes the assembly process of the positive stiffness component simple and repeatable, and allows for easy replacement of compliant curved beams with different cross-sections, materials or arc parameters to achieve the required positive stiffness curve, echoing the modular design of the negative stiffness component 1, and together improving the overall flexibility of the vibration isolator to adapt to different working conditions.
[0032] It should be noted that the preformed compliant beam 21 with positive stiffness in the positive stiffness component 2 and the compression buckling beam 11 with negative stiffness in the negative stiffness component 1 can be any other beam, plate, shell, arch, or other structure with the required stiffness characteristics.
[0033] refer to Figures 13-14 In one implementation, the torsional quasi-zero stiffness modules on the left and right sides are symmetrically arranged. The cantilever structure 5 includes a cantilever beam clamping support 50, on which a cantilever beam 53 is provided. The cantilever beam 53 and the cantilever beam clamping support 50 are connected by a cantilever beam connector. Connecting members are provided on both sides of the cantilever beam clamping support 50. The connecting members are connected to the inner ring 22 of the positive stiffness component and the inner ring 12 of the negative stiffness component. The top of the cantilever structure support base 6 is fixedly connected to the cantilever beam clamping support 50, and the two sides of the cantilever beam clamping support 50 are fixedly connected to the adjustable outer ring 10. This achieves precise coupling between the torsional degree of freedom at the root of the cantilever beam 53 and the quasi-zero stiffness module, while the remaining degrees of freedom are constrained by the fixed connection between the base and the clamping support. This bilateral symmetry... On the one hand, the configuration enables the quasi-zero stiffness modules on both sides of the cantilever beam 53 to generate equal and opposite torsional restoring moments when subjected to vibration excitation from the base. This avoids the eccentric loading or additional bending moment that may be caused by unilateral arrangement, ensuring the smooth motion of the cantilever structure 5 during torsional vibration isolation. On the other hand, since the modules on both sides can be preloaded independently, the stiffness characteristics of the left and right sides can be flexibly matched according to the actual load and working conditions of the cantilever beam 53, further improving the system's adaptability to asymmetric loads or complex vibration environments. At the same time, the cantilever structure 5, the vibration isolation module, and the cantilever structure support base 6 are integrated into a compact whole, which is convenient for direct installation in various engineering structures, achieving efficient isolation and convenient engineering application for low-frequency torsional vibration of the cantilever structure 5.
[0034] It should be noted that the connecting component is a square shaft, which passes through the square hole in both the inner ring 22 of the positive stiffness component and the outer ring of the negative stiffness component. On the one hand, the square shaft and the square hole, with no relative rotational fit, ensure that the torsional angle at the root of the cantilever beam 53 can be accurately and synchronously transmitted to the inner rings of the positive and negative stiffness components 1, so that the two always move with the same rotation angle and achieve accurate parallel superposition of stiffness, avoiding response lag or drift of quasi-zero stiffness characteristics caused by connection gaps or slippage. On the other hand, the square shaft, as a simple and high-load-bearing connection form, can effectively transmit the large torsional load generated during the operation of the cantilever beam 53 without plastic deformation or loosening. At the same time, the through-type design makes the inner rings of the two side modules and the cantilever beam clamping support 50 form an integral rotating component, further improving coaxiality and assembly accuracy. In addition, the square shaft connection corresponds to the aforementioned square hole design, ensuring that the force transmission path of the entire vibration isolator from the cantilever beam 53 to the stiffness modules on both sides is continuous and reliable, facilitating modular disassembly and maintenance.
[0035] The square holes in the inner ring 22 connecting the positive stiffness component, the square shaft adapter ring 31, and the inner ring 12 connecting the negative stiffness component can be selected from various hole shapes that can constrain rotational degrees of freedom, such as triangles, pentagons, and hexagons. At this time, it is necessary to adjust the cross-sectional shape of the connecting shafts on both sides of the cantilever beam clamping support 50 simultaneously.
[0036] refer to Figures 13-14 As one implementation, the cantilever beam connector includes a clamping plate 51 for clamping the cantilever beam 53 and clamping screws 52 that pass through the clamping plate 51, the cantilever beam 53 and the cantilever beam clamping support 50 in sequence. The cantilever beam clamping support 50, the clamping plate 51 and the cantilever beam 53 are designed with multiple through holes, and the clamping screws 52 are used to completely fasten each part of the cantilever structure 5.
[0037] refer to Figures 13-14 As one implementation method, the cantilever structure support base 6 includes a base body 60 and second arc-shaped connectors disposed on both sides of the base body 60. The arc of the second arc-shaped connector is consistent with the arc of the adjustable outer ring 10. A fixing nut 61 is provided on the second arc-shaped connector. The connecting screw 23 passes through the fixing nut 61, the connecting nut 13, the interlayer support ring 33, and the threaded hole in sequence to realize the connection of the cantilever structure support base 6, the adjustable outer ring 10, the first arc-shaped connector and the fixing outer ring 20. This achieves coaxial, uniform and reliable integrated fixation of the cantilever structure support base 6, the adjustable outer ring 10, the arc-shaped connector (bearing support component 3) and the fixing outer ring 20.
[0038] refer to Figures 11-12 By setting whether each of the n compression buckling beams 11 in the negative stiffness component 1 is in the upper or lower branch, the n+1 level discrete preload adjustment of the zero point of the rotation angle-moment relationship of the negative stiffness component 1 can be achieved. By selecting the negative stiffness of different branches, the discrete preload can be adjusted. Furthermore, the relative angle θ0 can be adjusted to adjust the relative angle between the stable equilibrium point of the positive stiffness component 2 and the unstable equilibrium point of the selected rotation angle-moment relationship branch of the negative stiffness component 1, thereby achieving continuous preload adjustment.
[0039] refer to Figures 13-16As one implementation method, taking four zero-stiffness modules on one side of the cantilever structure 5 as an example, the cantilever beam clamping support 50 is connected to the inner ring 22 of the positive stiffness component, the square shaft adapter ring 31, and the inner ring 12 of the negative stiffness component of the torsional quasi-zero stiffness module that is closely attached to the side of the cantilever structure support base 6. The cantilever structure support base 6 is fixed to the cantilever structure support base 6 by connecting screws 23 through the fixed outer ring 20 and the adjustable angle outer ring of the quasi-zero stiffness module that is closely attached to the side of the cantilever structure support base 6. Different quasi-zero stiffness modules are connected in adjacent order from the inside to the outside, with inner rings fixed to inner rings and outer rings fixed to outer rings. The connection between inner rings is fixed by the inner ring interlayer support ring 34 and screws and nuts, and the connection between outer rings is fixed by the interlayer support ring 33 and screws and nuts. This realizes the series connection of different torsional quasi-zero stiffness modules, and realizes the step-by-step superposition of the stiffness characteristics of each level of modules in the torque-rotation angle relationship. This results in multi-level quasi-zero stiffness segmented characteristics. Each module can be independently set with discrete preload levels and continuous preload adjustments, allowing the series-connected vibration isolator to exhibit multiple quasi-zero stiffness ranges as the torsional angle of the cantilever beam 53 increases, with each range corresponding to a different balance torque range. This series configuration significantly expands the effective isolation torque capacity and angular travel of the vibration isolator, overcoming the inherent limitation of the narrow quasi-zero stiffness range of a single module. Furthermore, through differentiated preload configurations at each module level, it enables segmented and efficient isolation of wide-bandwidth, variable-amplitude torsional vibrations. Simultaneously, the interlayer support ring 33 and the screw and nut fastening method ensure the axial compactness and detachability of the series structure, facilitating the addition or reduction of module numbers or adjustment of preload configurations at each level according to actual needs. This significantly improves the vibration isolator's engineering adaptability to large cantilever structures 5 or complex loads under multiple working conditions.
[0040] refer to Figure 16 By designing and adjusting the positions of different preloads, the multi-stage preload quasi-zero stiffness torque-rotation angle relationship of the series-connected quasi-zero stiffness vibration isolators can be realized.
[0041] It should be noted that the adjustable angle outer ring, the negative stiffness component connecting inner ring 12, the square shaft adapter ring 31, the bearing support parts, the fixed outer ring 20, the positive stiffness component connecting inner ring 22, the cantilever beam clamping support 50, the clamping plate 51, and the cantilever structure support base 6 can be made of various materials and processed in various ways. Materials include aluminum alloy, stainless steel, carbon fiber composite materials, engineering plastics (acrylonitrile-butadiene-styrene copolymer, ABS), etc. Processing methods include computer numerical control milling (CNC milling), computer numerical control turning (CNC turning), laser cutting, 3D printing (selective laser sintering, SLS; stereolithography, SLA), molding, carbon fiber lamination process, etc.
[0042] The compression buckling beam 11 and the preformed compliant beam 21 can be made of a variety of soft materials and processed in a variety of ways. Materials include silicone rubber (polydimethylsiloxane, PDMS), polyurethane elastomer (TPU), flexible epoxy resin, etc. Processing methods include soft mold casting, 3D printing (fused deposition modeling, FDM; photopolymerization of flexible materials), injection molding, dip coating, vulcanization, etc.
[0043] The compression buckling beam 11 and the preformed compliant beam 21 can also be made of rigid materials, such as aluminum alloys, stainless steel, carbon fiber composites, and engineering plastics (acrylonitrile-butadiene-styrene copolymer, ABS). Processing methods include computer numerical control milling (CNC milling), computer numerical control turning (CNC turning), laser cutting, 3D printing (selective laser sintering, SLS; stereolithography, SLA), molding, and carbon fiber lamination. However, it is necessary to consider whether the plastic strain of the material is exceeded under large deformation conditions to avoid irreversible plastic deformation of the vibration isolator.
[0044] Connecting nut 13, connecting screw 23, clamping screw 52, bearing 30, and fixing nut 61 are standard parts manufactured and sold on the market.
[0045] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures, characterized in that, The system includes a torsional quasi-zero stiffness module, a cantilever structure (5), and a cantilever structure support base (6) fixedly connected to the cantilever structure (5). The torsional quasi-zero stiffness module is provided on both sides of the cantilever structure (5) and the cantilever structure support base (6). At least one torsional quasi-zero stiffness module is provided on each side. The torsional quasi-zero stiffness module includes a positive stiffness component (2) and a negative stiffness component (1) exhibiting negative stiffness characteristics. The positive stiffness component (2) includes a fixed outer ring (20), a positive stiffness component connecting inner ring (22), and a connection for connecting the fixed outer ring (20) and the positive stiffness component. The preformed compliant curved beam (21) connecting the inner ring (22) includes an adjustable outer ring (10), a negative stiffness component connecting inner ring (12), and a compression buckling beam (11) for connecting the adjustable outer ring (10) and the negative stiffness component connecting inner ring (12). The positive stiffness component connecting inner ring (22) and the negative stiffness component connecting inner ring (12) are fixedly connected by a connector. The fixed outer ring (20) and the adjustable outer ring (10) are connected by a movable connector to realize the angle adjustment of the fixed outer ring (20) and the adjustable outer ring (10).
2. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 1, characterized in that, The cantilever structure support base (6) is provided with a second arc-shaped connector on both sides, and the arc of the second arc-shaped connector is consistent with the arc of the adjustable outer ring (10).
3. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 1, characterized in that, The cantilever structure (5) includes a cantilever beam clamping support (50), a cantilever beam (53) disposed on the cantilever beam clamping support (50), and a cantilever beam connector for connecting the cantilever beam clamping support (50) and the cantilever beam (53). Connecting members are provided on both sides of the cantilever beam clamping support (50). The connecting members are connected to the inner ring (22) of the positive stiffness component and the inner ring (12) of the negative stiffness component. The top of the cantilever structure support base (6) is fixedly connected to the cantilever beam clamping support (50), and both sides of the cantilever beam clamping support (50) are fixedly connected to the adjustable outer ring (10).
4. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 3, characterized in that, The cantilever beam connector includes a clamping plate (51) for clamping the cantilever beam (53) and clamping screws (52) that pass through the clamping plate (51), the cantilever beam (53) and the cantilever beam clamping support (50) in sequence.
5. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 1, characterized in that, The movable connector includes a waist-shaped hole on the adjustable outer ring (10), a threaded hole on the fixed outer ring (20), and a connecting screw (23) for connecting the waist-shaped hole and the threaded hole.
6. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 5, characterized in that, The connector includes square holes formed on the inner ring (12) connecting the negative stiffness component and the inner ring (22) connecting the positive stiffness component, and a square shaft for connecting the square holes.
7. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 6, characterized in that, A bearing support component (3) is provided between the positive stiffness component (2) and the negative stiffness component (1). The bearing support component (3) includes a square shaft adapter ring (31) connected to the square shaft, a bearing (30) sleeved on the outer periphery of the square shaft adapter ring (31), a bearing support member (32) provided on the outer periphery of the bearing (30), and a first arc-shaped connector provided at the end of the bearing support member (32) away from the square shaft adapter ring (31). The fixed outer ring (20), the adjustable outer ring (10), and the first arc-shaped connector are connected by the connecting screw (23).
8. The preload adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 7, wherein an interlayer support ring (33) is provided between the fixed outer ring (20) and the adjustable outer ring (10), the interlayer support ring (33) is provided on the fixed outer ring (20), and the interlayer support ring (33) is provided with a through hole communicating with the threaded hole.
9. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 1, characterized in that, At least three first T-shaped snap-fit grooves are provided in the circumferential direction of the adjustable outer ring (10) and the negative stiffness component connecting inner ring (12). The two ends of the compression buckling beam (11) are provided with first T-shaped connectors that snap into the first T-shaped snap-fit grooves. The length of the compression buckling beam (11) is less than the distance from the outer wall of the negative stiffness component connecting inner ring (12) to the inner wall of the adjustable outer ring (10).
10. The preload-adjustable torsional quasi-zero stiffness vibration isolator for cantilever structures according to claim 1, characterized in that, Both the fixed outer ring (20) and the inner ring (22) connecting the positive stiffness component are provided with at least three second T-shaped snap-fit grooves in the circumferential direction. The two ends of the preformed compliant curved beam (21) are provided with second T-shaped connectors that snap-fit with the second T-shaped snap-fit grooves. The length of the compliant curved beam is equal to the distance from the outer wall of the inner ring (22) connecting the positive stiffness component to the inner wall of the fixed outer ring (20).