Rigidity-adjustable damping-enhanced shock absorber

Abstract

The invention relates to the technical field of structural vibration reduction, and discloses a rigidity-adjustable damping-enhanced vibration absorber, comprising: a negative rigidity mechanism, the negative rigidity mechanism comprises a telescopic rod, a fixed rod and universal joints, and two ends of the telescopic rod and two ends of the fixed rod are fixedly connected with platforms through the universal joints respectively; the disc type damper is arranged on the middle platform; the series-parallel elastic mechanism comprises an upper end face, a lower end face and a supporting plate, the upper end face and the lower end face are installed at the two ends of a guide column in a sliding mode, the guide column is sleeved with a spring B, a middle column sequentially penetrates through the upper end face, the supporting plate and the lower end face, and a spring A is arranged between the supporting plate and the lower end face. The disc type damper is connected with the negative stiffness mechanism in parallel through the internal rotation freedom degree of the mechanism, the damping effect is enhanced, a series-parallel elastic mechanism matched with the disc type damper is designed, and finally the rigidity-adjustable damping-enhanced shock absorber is formed.

Description

Technical Field

[0001] The present invention relates to the technical field of structural vibration reduction, and more particularly to a stiffness-adjustable damping-enhanced vibration absorber. Background Art

[0002] Negative stiffness is a unique mechanical phenomenon in which a structure exhibits behavior that promotes, rather than resists, deformation when subjected to load. By combining negative stiffness with damping, the relative displacement between the two ends of the damper can be significantly amplified, thereby enhancing its energy dissipation effect. Conventional positive stiffness systems tend to return to their original shape when subjected to external forces, thereby resisting deformation. However, negative stiffness systems, on the other hand, tend to deform further when subjected to external forces. This property makes negative stiffness very useful in specific applications, particularly those requiring efficient energy dissipation.

[0003] Figure 1 A prototype vibration isolator was demonstrated. It features a foldable cylindrical structure with a torsional buckling mode. The structure consists of a linear spring, a steel shaft, and a universal joint. The isolator exhibits quasi-zero stiffness characteristics in the high-frequency range and effectively reduces vibrations.

[0004] However, negative stiffness often occurs during the structural bistable switching process, resulting in a narrow negative stiffness region, difficulty controlling the negative stiffness value, and difficulty ensuring robustness. Therefore, it is urgent to design a stiffness-adjustable damping-enhanced shock absorber to address these issues. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a stiffness-adjustable damping-enhanced shock absorber, which can achieve lower-frequency and wider-frequency vibration suppression, and can play a damping and energy-consuming role while isolating vibration.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A stiffness-adjustable damping-enhanced shock absorber, comprising:

[0008] A negative stiffness mechanism, comprising an upper platform, a lower platform, a middle platform, a telescopic rod, a fixed rod, and a universal joint. Both ends of the telescopic rod and the fixed rod are fixedly connected to each platform via a universal joint. The telescopic rod is designed to be inclined.

[0009] a disc damper, the disc damper being arranged on the middle platform;

[0010] A series-parallel elastic mechanism includes an upper end face, a lower end face, a support plate, a guide column, a middle column, a spring A and a spring B. The upper end face and the lower end face are slidably mounted on both ends of the guide column. The guide column is sleeved with the spring B. The middle column passes through the upper end face, the support plate and the lower end face in sequence. The support plate can move axially along the middle column. A spring A is provided between the support plate and the lower end face.

[0011] As a further improvement to the present invention, the middle platform is used as a symmetry plane, and the upper platform and the lower platform are symmetrical in the upper and lower directions.

[0012] As a further improvement to the present invention, a groove is provided on the middle platform, the outer ring of the disc damper is fixedly installed in the groove, and the middle column passes through the inner ring of the disc damper.

[0013] As a further improvement to the present invention, the upper and lower ends of the guide pillar are limited by screws and washers to prevent the upper end surface and the lower end surface from detaching from the guide pillar.

[0014] As a further improvement to the present invention, the upper platform is fixed to the upper end surface, and the two may be the same object.

[0015] As a further improvement to the present invention, the lower platform is fixed to the support plate, and the two may also be the same object.

[0016] As a further improvement to the present invention, the elastic restoring force of the negative stiffness mechanism in the initial stage of upper compression is opposite to the compression direction, presenting a large resistance.

[0017] As a further improvement to the present invention, as the compression deformation increases, the negative stiffness mechanism gradually expands or rearranges, the direction of the elastic restoring force changes, and the resistance decreases.

[0018] As a further improvement to the present invention, the relationship between the force and displacement of the negative stiffness mechanism is as follows:

[0019] Where h0 is the initial height of the platform, that is, the distance between the hinge centers of the upper and lower platforms when the hypotenuse A1B1 is vertical; n is the number of roots of the hypotenuse A1B1, r is the distance from the center of the platform to a sharp corner; θ is the relative rotation angle, which satisfies the following relationship:

[0020]

[0021] As a further improvement to the present invention, the shock absorber structural stiffness is: Where: k n is the stiffness of the negative stiffness mechanism, which has nonlinear characteristics; k A k is the stiffness of the spring A in the series-parallel elastic mechanism;B is the stiffness of the spring B in the series-parallel elastic mechanism, n B is the number of parallel springs.

[0022] The beneficial technical effects of the present invention are:

[0023] The connecting rods of the present invention are distributed in a columnar shape, and the number of connecting rods is adjustable, with a minimum of 3 and a maximum of dozens. The different number of connecting rods brings a large design space for the negative stiffness of the mechanism. Compared with the existing negative stiffness mechanism, the overall structure is more compact and lightweight, providing a better solution for applications in scenarios with limited space and weight. In addition, considering the principle that the negative stiffness mechanism promotes movement, the internal rotational freedom of the mechanism is utilized, and the disc damper is connected in parallel with the negative stiffness mechanism to enhance the damping effect. A matching series-parallel elastic mechanism is designed, and finally a damping-enhanced shock absorber with adjustable stiffness is formed.

[0024] When the overall stiffness of the present invention approaches zero, it becomes a quasi-zero-stiffness vibration isolation device. At this point, the system's natural frequency is extremely low. According to the principle that "an isolator can effectively suppress external excitation only when the excitation frequency is greater than √2 times the isolator's natural frequency," this device can achieve lower-frequency and wider-band vibration suppression compared to traditional linear spring isolators.

[0025] Compared to other quasi-zero-stiffness isolators, this invention incorporates a damping element, converting internal rotational motion into damper movement. This provides both vibration isolation and energy dissipation. Furthermore, the damping is connected in parallel with the stiffness of the negative-stiffness structure. Because negative-stiffness structures promote motion, this further amplifies the damping effect and improves energy dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a prototype diagram of a vibration isolator in the prior art.

[0027] Figure 2 It is a three-dimensional schematic diagram of the present invention.

[0028] Figure 3 It is a three-dimensional schematic diagram of the negative stiffness mechanism of the present invention.

[0029] Figure 4 It is a three-dimensional structural diagram of the series-parallel elastic mechanism in the present invention.

[0030] Figure 5 It is a three-dimensional schematic diagram of the disc damper in the present invention.

[0031] Figure 6 It is a schematic diagram of the compression process of the negative stiffness mechanism in the present invention.

[0032] Figure 7 It is a force-displacement curve relationship diagram in the present invention.

[0033] Figure 8 It is a force-rotation angle curve relationship diagram in the present invention.

[0034] In the figure: 1. Negative stiffness mechanism; 11. Upper platform; 12. Lower platform; 13. Middle platform; 131. Groove; 14. Telescopic rod; 15. Fixed rod; 16. Universal joint; 2. Disc damper; 3. Series-parallel elastic mechanism; 31. Upper end surface; 32. Lower end surface; 33. Support plate; 34. Guide column; 35. Middle column; 36. Spring A; 37. Spring B. DETAILED DESCRIPTION

[0035] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0036] Combine Figure 2 - Figure 8 , the present invention provides the following embodiments:

[0037] A stiffness-adjustable damping-enhanced shock absorber comprises: a negative stiffness mechanism 1, a disc damper 2, and a series-parallel elastic mechanism 3. These are combined together through a center column 35 and a guide column 34, and clamped between an upper end surface 31 and a lower end surface 32.

[0038] The negative stiffness mechanism 1 includes an upper platform 11, a lower platform 12, a middle platform 13, a telescopic rod 14, a fixed rod 15 and a universal joint 16. The ends of the telescopic rod 14 and the fixed rod 15 are fixedly connected to each platform through a universal joint 16. The telescopic rod 14 is designed to be inclined; the upper platform 11 and the lower platform 12 only perform axial movement and do not perform circumferential movement, which facilitates subsequent integration into the quasi-zero stiffness vibration isolator.

[0039] The disc damper 2 is arranged on the middle platform 13; the series-parallel elastic mechanism 3 includes an upper end surface 31, a lower end surface 32, a support plate 33, a guide column 34, a middle column 35, a spring A36 and a spring B37. The upper end surface 31 and the lower end surface 32 are slidably mounted on both ends of the guide column 34. The guide column 34 is sleeved with a spring B37. The middle column 35 passes through the upper end surface 31, the support plate 33 and the lower end surface 32 in sequence. The support plate 33 can move axially along the middle column 35. A spring A36 is provided between the support plate 33 and the lower end surface 32.

[0040] As another preferred embodiment of the present invention, the middle platform 13 is used as the symmetry plane, and the upper platform 11 and the lower platform 12 are symmetrical in the vertical direction. Figure 1 and Figure 3Specifically, in this embodiment, the fixed rod 14 and telescopic rod 15 structure provided on the upper platform 11 and the middle platform 13 are also designed in the same way between the middle platform 13 and the lower platform 12, with the same inclination angle but opposite inclination directions.

[0041] As another preferred embodiment of the present invention, a groove 131 is provided on the middle platform 13, the outer ring of the disc damper 2 is fixedly installed in the groove 131, and the middle column 35 passes through the inner ring of the disc damper 2. Figure 1 and Figure 6 When the middle platform 13 rotates, the disc damper 2 provides corresponding damping, which plays a role in damping energy consumption. The negative stiffness mechanism 1 and the disc damper 2 form a parallel structure. Due to the characteristics of the negative stiffness structure that promotes movement, the damping effect can be further amplified to improve energy consumption.

[0042] As another preferred embodiment of the present invention, the upper and lower ends of the guide pillar 34 are limited by screws and washers to prevent the upper end surface 31 and the lower end surface 32 from detaching from the guide pillar 34. The upper and lower end limits are stable, effectively preventing detachment and ensuring the stability of the entire shock absorber.

[0043] As another preferred embodiment of the present invention, the upper platform 11 is fixed to the upper end surface 31, and the two can be the same object. Furthermore, the lower platform 12 is fixed to the support plate 33, and the two can also be the same object. Figure 1 In this embodiment, the upper platform 11 and the upper end surface 31 are designed as one object, and the lower platform 12 and the support plate 33 are designed as the same object, which can save more materials, facilitate installation and production, and the overall structure is simpler and more stable.

[0044] As another preferred embodiment of the present invention, during the initial stage of upper compression, the elastic restoring force of the negative stiffness mechanism 1 is opposite to the direction of compression, resulting in a large resistance. Specifically, during the compression process of the negative stiffness mechanism 1, the initial stage presents a large resistance due to the compact structure and the direction of the elastic restoring force of the material being opposite to the direction of compression.

[0045] As another preferred embodiment of the present invention, as the compressive deformation increases, the negative stiffness mechanism 1 gradually expands or rearranges, changing the direction of the elastic restoring force and reducing the resistance. Specifically, as the compressive deformation increases, the structure gradually expands or rearranges, and the direction of the material's elastic restoring force changes, even aligning with the compression direction, thereby reducing the resistance and achieving negative stiffness characteristics.

[0046] As another preferred embodiment of the present invention, the relationship between the force and displacement of the negative stiffness mechanism 1 is as follows:

[0047] Where h0 is the initial height of the platform, that is, the distance between the hinge centers of the upper and lower platforms when the hypotenuse A1B1 is vertical; n is the number of roots of the hypotenuse A1B1, r is the distance from the center of the platform to a sharp corner; θ is the relative rotation angle, which satisfies the following relationship:

[0048]

[0049] Combine Figure 6 Specifically, the original lengths of the hypotenuse A1B1 and the diagonal side A4B2 are: Where: h0 is the initial height of the platform, that is, the distance between the hinge centers of the upper and lower platforms when the hypotenuse A1B1 is vertical; n is the number of roots of the hypotenuse A1B1.

[0050] When the upper and lower platforms are compressed, the entire mechanism is in a compressed state. Assume that when the upper platform 11 is compressed downward by a distance x, the height between the two platforms after translation is h, and the relative rotation angle is θ. The angle θ must satisfy the following relationship to ensure that the truss rods do not interfere with each other during translation (the actual volume of the rods is not considered here).

[0051] The length of the diagonal side A1B1 is:

[0052]

[0053] The diagonal side A1B1 is a rigid rod with great rigidity, so the elastic deformation can be ignored. Then we have

[0054]

[0055] The solution is:

[0056]

[0057] The lengths of the diagonal sides A4B2 are:

[0058]

[0059] According to Hooke's law, the axial forces on the diagonal edges A4B2 are:

[0060]

[0061] In the vertical direction, during the quasi-static compression process, the static equilibrium equations of the elastic truss and the external load in the vertical and circumferential directions are:

[0062]

[0063] eliminate have to

[0064]

[0065] Substituting the length of the diagonal side A4B2 and the axial force on the elastic element of the diagonal side A4B2 into the above formula, we can obtain:

[0066]

[0067] in:

[0068] After obtaining the relationship between axial displacement and external load, the vertical stiffness of the structure during quasi-static compression and the elastic potential energy during deformation are obtained by derivation:

[0069]

[0070] When n=6, h=20mm, r=10mm, When the force-displacement and force-rotation angle relationship curves are as follows Figure 7 and Figure 8 It can be seen that this structure has pressure-bearing capacity within the compression stroke of 7.5mm. During this period, the slope of its force-displacement curve is negative, that is, the dynamic stiffness is negative stiffness, which is 75% of the total stiffness and 37.5% of the total height of the structure.

[0071] As another preferred embodiment of the present invention, the shock absorber structural stiffness is: Where: k n is the stiffness of negative stiffness mechanism 1, which has nonlinear characteristics; k A is the stiffness of spring A36 in the series-parallel elastic mechanism 3; k B is the stiffness of spring B37 in the series-parallel elastic mechanism 3, n B is the number of parallel springs. When k≈0, the rigid structure is a quasi-zero stiffness isolator; when k>0, it is a positive stiffness isolator, and its internal negative stiffness mechanism has a damping amplification effect, that is, a negative stiffness damping amplification isolator.

[0072] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A stiffness-adjustable damping-enhanced shock absorber, characterized in that: include: A negative stiffness mechanism (1), comprising an upper platform (11), a lower platform (12), a middle platform (13), a telescopic rod (14), a fixed rod (15) and a universal joint (16), wherein both ends of the telescopic rod (14) and the fixed rod (15) are fixedly connected to each platform via the universal joint (16), and the telescopic rod (14) is of an inclined design; a disc damper (2), the disc damper (2) being arranged on the middle platform (13); A series-parallel elastic mechanism (3) includes an upper end surface (31), a lower end surface (32), a support plate (33), a guide column (34), a middle column (35), a spring A (36) and a spring B (37). The upper end surface (31) and the lower end surface (32) are slidably mounted on both ends of the guide column (34). The guide column (34) is sleeved with the spring B (37). The middle column (35) passes through the upper end surface (31), the support plate (33) and the lower end surface (32) in sequence. The support plate (33) can move axially along the middle column (35). A spring A (36) is provided between the support plate (33) and the lower end surface (32).

2. The stiffness-adjustable damping-enhanced shock absorber according to claim 1, characterized in that: With the middle platform (13) as a symmetry plane, the upper platform (11) and the lower platform (12) are symmetrical in the vertical direction.

3. The stiffness-adjustable damping-enhanced shock absorber according to claim 2, characterized in that: A groove (131) is provided on the middle platform (13), the outer ring of the disc damper (2) is fixedly installed in the groove (131), and the middle column (35) passes through the inner ring of the disc damper (2).

4. The stiffness-adjustable damping-enhanced shock absorber according to claim 3, characterized in that: The upper and lower ends of the guide pillar (34) are limited by screws and washers to prevent the upper end surface (31) and the lower end surface (32) from detaching from the guide pillar (34).

5. The stiffness-adjustable damping-enhanced shock absorber according to claim 4, characterized in that: The upper platform (11) is fixed to the upper end surface (31), and the two can be the same object.

6. The stiffness-adjustable damping-enhanced shock absorber according to claim 5, characterized in that: The lower platform (12) is fixed to the support plate (33), and the two may also be the same object.

7. The stiffness-adjustable damping-enhanced shock absorber according to claim 1, characterized in that: The elastic restoring force of the negative stiffness mechanism (1) in the initial stage of upper compression is opposite to the compression direction, presenting a large resistance.

8. The stiffness-adjustable damping-enhanced shock absorber according to claim 7, characterized in that: As the compression deformation increases, the negative stiffness mechanism (1) gradually expands or rearranges, the direction of the elastic restoring force changes, and the resistance decreases.

9. The stiffness-adjustable damping-enhanced shock absorber according to claim 8, characterized in that: The relationship between the force and displacement of the negative stiffness mechanism (1) is as follows: Where h0 is the initial height of the platform, that is, the distance between the hinge centers of the upper and lower platforms when the hypotenuse A1B1 is vertical; n is the number of roots of the hypotenuse A1B1, r is the distance from the center of the platform to a sharp corner; θ is the relative rotation angle, which satisfies the following relationship:

10. The stiffness-adjustable damping-enhanced shock absorber according to claim 9, characterized in that: The structural stiffness of the shock absorber is: Where: k n is the stiffness of the negative stiffness mechanism, which has nonlinear characteristics; k A k is the stiffness of the spring A (36) in the series-parallel elastic mechanism (3); B is the stiffness of the spring B (37) in the series-parallel elastic mechanism (3), n B is the number of parallel springs.

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