Nonlinear energy trap device and design method thereof

Abstract

The invention relates to the technical field of structural engineering, in particular to a nonlinear energy trap device and a design method thereof. When in use, the nonlinear energy trap device is mounted on a flexible structure for controlling vibration, and comprises a support frame mounted on the flexible structure, and a movable mass block arranged in the support frame and allowed to move in a vibration plane of the flexible structure, the nonlinear spring assembly is arranged between the movable mass block and the supporting frame and movably connected with the movable mass block and / or the supporting frame, and the damping assembly is arranged between the mass block and the supporting frame. According to the nonlinear energy sink device provided by the invention, the nonlinear spring assembly is in contact connection with the single side of the moving mass block through the geometric arrangement of the spring, so that the softening characteristic that the rigidity is reduced along with the increase of deformation is realized, and the same control effect on low-frequency large-amplitude vibration and high-frequency small-amplitude vibration can be achieved; therefore, an excellent control effect on multi-order modal vibration of the flexible structure under loads such as wind can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of structural engineering, and in particular to a non-linear energy sink device and a design method thereof. Background Art

[0002] With the rapid development of modern civil, transportation, and aerospace engineering, higher requirements are put forward for the construction and operation and maintenance of long-span and extended space structures, high-rise mast structures, and long-span bridge structures. These structures have low natural vibration frequencies and dense modal distributions. Coupled with the use of slender forms and lightweight and high-strength materials, they have low self-damping and weak energy dissipation capabilities, and are prone to large-amplitude, long-duration, and multi-modal vibrations under dynamic actions such as wind, earthquake, and operating loads, seriously threatening the serviceability and long-term safety of the structures. Therefore, it is urgent to study vibration control methods and devices for such structures.

[0003] The vibration control of flexible structures mainly relies on the collaborative application of aerodynamic measures and mechanical measures. In response to wind loads, aerodynamic measures are widely used due to their effectiveness, and their core lies in optimizing the cross-sectional shape of the structure. For example, by setting depressions or winding helical lines on the surface of stay cables and suspension cables, the formation of water lines and vortices can be effectively destroyed, thereby reducing aerodynamic excitation forces. For the cross-section of bridge girders, vibration control is often achieved by adding flow deflectors, suppressing plates, or using separated cross-sections. Although a variety of mature aerodynamic measures have been developed in the field of structural wind engineering, these measures are highly sensitive to dynamic parameters such as the structure shape and damping. During long-term operation, changes in the structure shape caused by factors such as dust accumulation and ice and snow coverage may render the aerodynamic measures ineffective and even cause other types of vibration problems.

[0004] Therefore, in engineering practice, mechanical measures have gradually become an important supplement to aerodynamic measures, achieving stable control of various vibrations by increasing the structural damping. The key performance indicators of mechanical devices include the damping value they can provide and the vibration modal range they cover. Currently, various types of dampers have been widely used in structural vibration reduction and isolation, such as tuned mass dampers (TMDs), viscous dampers, high-damping rubber dampers, and eddy current dampers. These dampers can be roughly divided into two categories: one is the damper that does not require bracket installation, such as the tuned mass damper; the other is the damper that requires bracket installation. The damper that requires bracket installation can only be installed near the ends or supports in long-span structures, so the vibration reduction effect is limited. Although the tuned mass damper can be installed at any position of the structure, its single device can only be optimized for a single mode, and there are problems of low device efficiency and high cost in the multi-modal vibration control of flexible structures.

[0005] In view of the limitations of the above-mentioned dampers and tuned mass dampers, the non-linear energy sink (NES) has received extensive attention in the wide-frequency multi-modal vibration reduction of structures. By introducing a non-linear spring, the non-linear energy sink can dynamically adjust its characteristic frequency according to the vibration characteristics, thereby achieving better vibration reduction effects in a relatively wide frequency band. Therefore, the properties of the non-linear spring become the key to its vibration reduction effect. The non-linear springs of traditional non-linear energy sinks mostly have "hardening" characteristics, that is, as the amplitude increases, the spring stiffness coefficient increases and the corresponding frequency increases. However, the low-frequency vibration amplitude of flexible structures is usually large, while the high-frequency vibration amplitude is small. Therefore, a non-linear energy sink with a natural vibration frequency that decreases as the amplitude increases is required.

[0006] At present, the multi-modal vibration control of long-span flexible structures remains a difficult problem to be solved urgently. Although non-linear energy sinks have been applied in engineering practice, their natural vibration characteristics still cannot fully meet the requirements of multi-modal vibration control of flexible structures, especially the lack of non-linear energy sinks suitable for multi-modal vibration reduction and their design methods. Summary of the Invention

[0007] To solve the above problems, the purpose of the present invention is to provide a non-linear energy sink device and its design method. In the non-linear energy sink device provided by the present invention, the non-linear spring assembly realizes the softening characteristic of decreasing stiffness with the increase of deformation through the geometric arrangement of the spring and the unilateral contact connection with the moving mass block, and can achieve the same control effect on low-frequency large-amplitude vibrations and high-frequency small-amplitude vibrations. Therefore, it can improve the excellent control effect on the multi-order modal vibrations of flexible structures under loads such as wind. The non-linear energy sink device provided by the present invention is suitable for multi-modal vibration reduction and can be applied to flexible structures such as bridge cables and main girders.

[0008] The non-linear energy sink device of the present invention includes a moving mass block, a support frame, a non-linear spring assembly, and a damping assembly; wherein, the non-linear spring unit is arranged between the moving mass block and the support frame (horizontally), and provides a non-linear restoring force when the moving mass block and the support frame move relatively, and its stiffness decreases with the increase of the amplitude to meet the requirements of multi-modal vibration control; the damping assembly is arranged between the moving mass block and the support frame (vertically / horizontally) and provides a damping force when the moving mass block moves.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] The first object of the present invention is to provide a non-linear energy trap device, which is installed on a flexible structure during use for controlling vibration. The device includes a support frame installed on the flexible structure, a moving mass block disposed within the support frame and allowed to move within the vibration plane of the flexible structure, a non-linear spring assembly disposed between the moving mass block and the support frame and movably connected to the moving mass block and / or the support frame, and configured to provide a non-linear restoring force when relative movement occurs between the moving mass block and the support frame, and a damping assembly disposed on the bottom of the mass block and the upper surface of the support frame, and configured to provide a damping dissipation capacity when relative movement occurs between the moving mass block and the support frame.

[0011] In an embodiment of the present invention, a plurality of the non-linear spring assemblies are disposed around the moving mass block, or a plurality of the non-linear spring assemblies are disposed along the inner wall of the support frame.

[0012] In an embodiment of the present invention, the non-linear spring assemblies disposed along the axial direction of the moving mass block are allowed to be symmetrically and / or staggeredly arranged.

[0013] In an embodiment of the present invention, each group of the non-linear spring assemblies includes two identical spring members. One end of the two spring members is connected by an auxiliary connecting member and forms an angle, and the other end of the two spring members is fixedly connected to the moving mass block or the support frame;

[0014] When the two spring members are squeezed, the connection point thereof deforms along the angle bisector, providing a restoring force opposite to the deformation direction, and the corresponding stiffness coefficient decreases as the deformation increases.

[0015] In the present invention, the auxiliary connecting member only bears pressure through contact, and its gap with the moving mass block or the support frame can be set according to actual needs.

[0016] In an embodiment of the present invention, the two spring members are respectively fixedly connected to the moving mass block through fixed connecting members and are in contact connection with the support frame;

[0017] Or, the two spring members are respectively connected to the support frame through fixed connecting members and are in contact connection with the moving mass block;

[0018] A limiting member is provided at the central position of the two fixed connecting members.

[0019] In an embodiment of the present invention, the angle formed by the two spring members and the auxiliary connecting member is greater than 0° and less than 180°;

[0020] When the auxiliary connecting member is in contact with the limiting member, the axes of the two spring members coincide.

[0021] When the maximum deformation is achieved by the limiting member such that the axes of the two spring members coincide, the restoring force and stiffness provided by the spring members are reduced to zero at this time.

[0022] In one embodiment of the present invention, the spring members are linear springs. One end of the two linear springs is connected by a first connecting hinge and forms an angle, and the other ends of the two spring members are fixedly connected to the moving mass block or the support frame through fixed connecting members.

[0023] In one embodiment of the present invention, the spring member includes a spring telescopic guide rod, a linear spring sleeved on the outer surface of the spring telescopic guide rod, and a screw frame for pre-compressing the linear spring and sleeved on the outer surface of the spring telescopic guide rod;

[0024] The screw frame includes a first end plate and a second end plate provided at both ends of the linear spring, and screws arranged along the circumferential direction of the linear spring and fixedly extending out of the first end plate and the second end plate in sequence; the screws are fixedly connected to the first end plate and movably connected to the second end plate;

[0025] One end of the spring guide rod is connected by a connecting block and forms an angle, and the other ends of the two spring guide rods are fixedly connected to the moving mass block or the support frame through fixed connecting members.

[0026] In one embodiment of the present invention, the linear spring and the screw frame are allowed to move along the axis direction of the spring telescopic guide rod;

[0027] When the spring member is compressed, the spring telescopic guide rod is compressed, and the screw allows the second end plate to move towards the direction close to the first end plate, allowing the linear spring to be further compressed.

[0028] In one embodiment of the present invention, the maximum distance between the first end plate and the second end plate is less than the initial length of the linear spring.

[0029] In one embodiment of the present invention, the damping assembly includes a first damping member provided at the bottom of the moving mass block, and a second damping member provided on the upper surface of the support frame and adapted to the first damping member; the first damping member is adapted to the second damping member;

[0030] The first damping member is selected from one of a viscous damper, an eddy current damper, a high damping rubber damper or a friction damper, and the second damping member is selected from one of a viscous damper, an eddy current damper, a high damping rubber damper or a friction damper;

[0031] Or, the damping assembly is a third damping member parallel to the movement plane of the moving mass block, provided on the side surface of the moving mass block and connected to the moving mass block and the support frame;

[0032] The third damping member is selected from one of a viscous damper or a magnetorheological damper.

[0033] In an embodiment of the present invention, a plurality of the first damping members are allowed to be arranged in parallel at intervals along the width direction of the second damping member.

[0034] In an embodiment of the present invention, the first damping member and the second damping member are spaced apart by greater than or equal to 5 mm in the height direction.

[0035] In an embodiment of the present invention, the third damping member is connected to the moving mass block through a second connecting hinge and connected to the support frame through a third connecting hinge.

[0036] In an embodiment of the present invention, the support frame is fixed to the flexible structure through an adapter to ensure that the movement direction of the moving mass block is consistent with the vibration direction of the flexible structure;

[0037] The bottom of the moving mass block is provided with universal wheels.

[0038] In the present invention, when the moving mass block moves towards the support frame and compresses the linear spring, the non-linear spring assembly generates a restoring force, and the non-linear spring assembly on the opposite side is separated from the moving mass block and does not provide a restoring force; the stiffness of the non-linear spring assembly decreases with the increase of the compression amount, having a softening characteristic; the damping assembly can connect the mass block and the support frame, or can be arranged in parallel with the non-linear spring assembly; by increasing the softening characteristic through spring deformation, the same control effect can be achieved for low-frequency large-amplitude vibration and high-frequency small-amplitude vibration, so that excellent control effects can be achieved for the multi-order modal vibration of the flexible structure under loads such as wind.

[0039] The second object of the present invention is to provide a design method for a non-linear energy sink device, including the following steps:

[0040] (S1) Denote the sum of the masses of the moving objects as m;

[0041] Among them, the moving objects include a moving mass block, a non-linear spring assembly, a damping assembly, and universal wheels;

[0042] (S2) Deduce the relationship between the restoring force f of the non-linear spring assembly and the deformation u: f u (u);

[0043] (S3) Deduce the relationship between the stiffness k of the non-linear spring assembly and the deformation:

[0044]

[0045] (S4) Calculate the relationship between the natural vibration frequency ω of the non-linear energy sink and the deformation:

[0046]

[0047] (S5) Adjust the parameters of the nonlinear spring according to the frequency range of the target-covered flexible structure and the optimal control amplitude of each order of mode.

[0048] In an embodiment of the present invention, each of the nonlinear spring assemblies is formed by connecting one end of two linear springs, and the other ends of the two linear springs are fixed on the moving mass block. The two linear springs are pre-compressed through one-way limiting guide rods respectively, and the pre-compression force is F0 (N), and the spring stiffness coefficient is k (N / m); the length of the base of the isosceles triangle formed by the two springs and their fixed connection lines is denoted as 2l (m), and the height is denoted as h (m). The initial length of the spring is:

[0049]

[0050] In an embodiment of the present invention, when the moving mass block compresses it by u (m) along the bisector direction of the two linear springs, the spring length becomes:

[0051]

[0052] The corresponding increase in the compression amount of the linear spring in the axial direction is Δ (m), and the pressure in the spring is:

[0053]

[0054] The resultant force of the force components of the two linear springs along the deformation u direction is:

[0055]

[0056] The corresponding stiffness coefficient is k u (N / m):

[0057]

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) In the non-linear energy well device provided by the present invention, the nonlinear spring has the characteristic that the stiffness coefficient decreases with the increase of the amplitude, which can meet the multi-modal vibration reduction requirements of the flexible structure;

[0060] (2) The non-linear energy well device provided by the present invention utilizes linear springs and geometric non-linearity to achieve the target non-linear stiffness characteristics, and has the advantages of easy implementation and controllable cost;

[0061] (3) The design method of the non-linear energy well provided by the present invention provides an analytical calculation formula for the design of the non-linear energy well, which is convenient for engineering design. Description of the Drawings

[0062] Figure 1 Plan view of the non - linear energy trap device described in Embodiment 1;

[0063] Figure 2 Cross - sectional view (A - A) of the non - linear energy trap device described in Embodiment 1;

[0064] Figure 3 Plan view (1) of the non - linear energy trap device described in Embodiment 1 after the moving mass block moves;

[0065] Figure 4 Cross - sectional view (B - B) of the non - linear energy trap device described in Embodiment 1 after the moving mass block moves;

[0066] Figure 5 Plan view (2) of the non - linear energy trap device described in Embodiment 1 after the moving mass block moves;

[0067] Figure 6 Cross - sectional view (C - C) of the non - linear energy trap device described in Embodiment 1 after the moving mass block moves;

[0068] Figure 7 Assembly drawing (1) of the non - linear spring assembly in the non - linear energy trap described in Embodiment 1;

[0069] Figure 8 Assembly drawing (2) of the non - linear spring assembly in the non - linear energy trap described in Embodiment 1;

[0070] Figure 9 Calculation model diagram of the non - linear spring assembly in the non - linear energy trap described in Embodiment 2;

[0071] Figure 10 Relationship curve diagram of the restoring force and deformation of a single non - linear spring assembly in Embodiment 2;

[0072] Figure 11 Relationship curve diagram of the equivalent stiffness coefficient and deformation of a single non - linear spring assembly in Embodiment 2;

[0073] Figure 12 Plan view of the non - linear energy trap device described in Embodiment 3;

[0074] Figure 13 Cross - sectional view (D - D) of the non - linear energy trap device described in Embodiment 3;

[0075] Figure 14 Plan view of the non - linear energy trap device described in Embodiment 4;

[0076] Figure 15Plan view (E-E) of the non-linear energy sink device described in Embodiment 4;

[0077] Figure 16 Displacement and corresponding time-frequency diagram of the non-linear energy sink device described in Embodiment 4 during the free decay vibration period;

[0078] Reference numerals in the figure: 1, moving mass block; 2, support frame; 3, non-linear spring assembly; 4, damping assembly; 3-1, linear spring; 3-2, fixed connecting piece; 3-3, first connecting hinge; 3-4, limiting piece; 3-5, spring telescopic guide rod; 3-6, screw; 3-7, first end plate; 3-8, second end plate; 3-9 connecting block; 4-1, first damping piece; 4-2, second damping piece; 4-3, third damping piece; 4-4, second connecting hinge; 4-5, third connecting hinge. Detailed implementation manners

[0079] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0080] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0081] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under", and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0082] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left", "right", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meanings.

[0083] In the following embodiments, unless otherwise specified, the structures or components used are conventional structures or components in the art, as long as they can achieve the corresponding functions.

[0084] Embodiment 1

[0085] This embodiment provides a non - linear energy well device, which is installed on a flexible structure during use for vibration control. As Figures 1 - 2 shown, it includes a support frame 2 installed on the flexible structure, a moving mass block 1 disposed within the support frame 2 and allowed to move within the vibration plane of the flexible structure, a non - linear spring assembly 3 disposed between the moving mass block 1 and the support frame 2 and movably connected to the moving mass block 1 and / or the support frame 2 for providing a non - linear restoring force when relative movement occurs between the moving mass block 1 and the support frame 2, and a damping assembly 4 disposed between the moving mass block 1 and the support frame 2 for providing a damping dissipation capacity when relative movement occurs between the moving mass block 1 and the support frame 2.

[0086] Among them, the moving mass block 1 is square, the support frame 2 is a square box - like structure (open at the top), and universal wheels 5 are provided at the bottom of the moving mass block 1, allowing the moving mass block 1 to slide in any horizontal direction within the support frame 2; two non - linear spring assemblies 3 are installed on each of the four sides of the moving mass block 1 (a total of 8 groups, symmetrically arranged on both sides in the same direction; several groups can be set according to actual situations, and the non - linear spring assemblies 3 arranged along the axis of the moving mass block 1 are allowed to be symmetrically and / or staggeredly arranged). In the static state, the other end (connection hinge) of the non - linear spring assembly 3 contacts but is not connected to the support frame 2 (the connection hinge only bears pressure through contact, and its gap with the moving mass block 1 or the support frame 2 can also be set according to actual needs).

[0087] As Figures 3 - 6 shown, when the moving mass block 1 moves relative to the support frame 2, the compressed non - linear spring assembly 3 deforms to provide a restoring force; on the side where the moving mass block 1 is away from the support frame 2, the non - linear spring assembly 3 disengages from the support frame 2 and does not provide any force to the moving mass block 1.

[0088] As Figure 7 and Figure 8As shown in the figure, each set of non-linear spring assemblies 3 includes two identical spring members. One end of the two spring members is connected by an auxiliary connecting member and forms an angle. The other end of the two spring members is fixedly connected to the moving mass block 1 or the support frame 2; the auxiliary connecting member only bears pressure through contact, and its gap with the moving mass block 1 or the support frame 2 can be set according to actual needs; the two spring members are respectively fixedly connected to the moving mass block 1 through fixed connecting members 3-2 and are in contact connection with the support frame 2; or, the two spring members are respectively connected to the support frame 2 through fixed connecting members 3-2 and are in contact connection with the moving mass block 1; the angle formed by the two spring members and the auxiliary connecting member is 60° (which can be adjusted to be greater than 0° and less than 180° according to actual conditions); a limiting member 3-4 is arranged at the central position of the two fixed connecting members 3-2 (the arrangement of the limiting member 3-4 ensures that when the connecting hinge contacts the limiting member 3-4, the axes of the two linear springs 3-1 coincide); when the two spring members are squeezed, their connection points deform along the angle bisector, providing a restoring force opposite to the deformation direction, and the corresponding stiffness coefficient decreases as the deformation increases; through the limiting member 3-4, the maximum deformation is when the axes of the two spring members coincide, and at this time, the restoring force and stiffness provided by the spring members are reduced to zero.

[0089] Preferably, the spring member is a linear spring 3-1. One end of the two linear springs 3-1 is connected by a first connecting hinge 3-3 and forms an angle. The other end of the two spring members is fixedly connected to the moving mass block 1 or the support frame 2 through fixed connecting members 3-2; the linear spring 3-1 and the fixed connecting member 3-2 form an equilateral triangle. The two linear springs 3-1 are respectively the two waists of the triangle, and the limiting member 3-4 limits the maximum compression amount of the linear spring 3-1 to the length of the height of the base of the triangle ( Figure 7 ).

[0090] Preferably, the spring member includes a spring telescopic guide rod 3-5, a linear spring 3-1 sleeved on the outer surface of the spring telescopic guide rod 3-5, and a screw frame for pre-compressing the linear spring 3-1 and sleeved on the outer surface of the spring telescopic guide rod 3-5; the screw frame includes a first end plate 3-7 and a second end plate 3-8 arranged at both ends of the linear spring 3-1, and screws 3-6 arranged circumferentially along the linear spring 3-1 and fixedly extending out of the first end plate 3-7 and the second end plate 3-8 in sequence; the screw 3-6 is fixedly connected to the first end plate 3-7 and is movably connected to the second end plate 3-8; one end of the spring guide rod is connected by a connecting block 3-9 and forms an angle, and the other end of the two spring guide rods is fixedly connected to the moving mass block 1 or the support frame 2 through fixed connecting members 3-2 ( Figure 8 )。

[0091] Further preferably, the linear spring 3-1 and the screw rod frame are allowed to move along the axial direction of the spring telescopic guide rod 3-5; when the spring member is compressed, the spring telescopic guide rod 3-5 is compressed, and the screw rod 3-6 allows the second end plate 3-8 to move towards the direction close to the first end plate 3-7, allowing the linear spring 3-1 to be further compressed; in an embodiment of the present invention, the maximum distance between the first end plate 3-7 and the second end plate 3-8 is less than the initial length of the linear spring 3-1.

[0092] The damping assembly 4 is an eddy current damper (which can be selected according to actual situations, for example: viscous damper, eddy current damper, high damping rubber damper or friction damper), and includes a first damper 4-1 (permanent magnet) provided at the bottom of the moving mass block 1, and a second damper 4-2 (copper plate conductor) provided on the upper surface of the support frame 2 and adapted to the first damper 4-1; when the moving mass block 1 and the support frame 2 move relatively, the copper plate conductor will cut the magnetic induction lines in the magnetic field to generate current and consume the movement energy.

[0093] Among them, one first damper 4-1 is arranged in parallel at intervals along the width direction of the second damper 4-2 (several groups can be arranged according to actual situations), and the distance between the first damper 4-1 and the second damper 4-2 along the height direction is greater than or equal to 5 mm.

[0094] The support frame 2 is fixed on the flexible structure through an adapter to ensure that the movement direction of the moving mass block 1 is consistent with the vibration direction of the flexible structure.

[0095] Embodiment 2

[0096] This embodiment provides a design method for the non-linear energy well device (the non-linear spring assembly 3 is the Figure 7 non-linear spring assembly 3 shown) described in Embodiment 1, which is specifically as follows:

[0097] (S1): Calculate the mass of the moving components such as the moving mass block 1, denoted as m;

[0098] (S2): Deduce the relationship formula f u (u) between the restoring force of the non-linear spring assembly 3 and the deformation (u);

[0099] (S3): Deduce the relationship formula between the stiffness of the non-linear spring assembly 3 and the deformation (u)

[0100]

[0101] (S4): Estimate the relationship formula between the natural vibration circular frequency ω (rad / s) of the non-linear energy well and the deformation

[0102]

[0103] (S5): Adjust the parameters of the nonlinear spring according to the frequency range of the target covering flexible structure and the optimal control amplitude of each order mode.

[0104] In this embodiment, as Figure 9 shown, each of the nonlinear spring assemblies 3 is composed of two linear springs 3-1 whose one ends are connected by a connecting hinge, and the other ends of the two linear springs 3-1 are fixed on the moving mass block 1. The two linear springs 3-1 are respectively pre-compressed by a unidirectional limiting guide rod, and the pre-compression force is F0 (N), and the spring stiffness coefficient is k (N / m); the length of the base of the isosceles triangle formed by the two springs and their fixed connection lines is denoted as 2l (m), and the height is denoted as h (m), and the initial length of the spring:

[0105]

[0106] In an embodiment of the present invention, when the moving mass block 1 is compressed by u (m) along the bisector direction of the intersection of the two linear springs 3-1, the spring length becomes:

[0107]

[0108] The corresponding increase in the compression amount of the linear spring 3-1 in the axial direction is Δ (m), and the pressure in the spring is:

[0109]

[0110] The resultant force of the force components of the two linear springs 3-1 along the deformation u direction is:

[0111]

[0112] The corresponding stiffness coefficient is k u (N / m):

[0113]

[0114] Take the pre-compression force F0 = 0, k = 1800 N / m, h = 0.12 m, l = 0.12 m; the relationship curve between the restoring force and the deformation of a single nonlinear spring assembly 3 obtained by using the above formula is as Figure 10 shown, and the relationship curve between the equivalent stiffness coefficient and the deformation is as Figure 11 shown. Combining Figure 11 and Figures 1 - 2 , two nonlinear spring assemblies 3 are installed on each side. When the deformation is small, the stiffness coefficient is about 1900 N / m. When the deformation reaches 0.105 m, the stiffness coefficient is reduced to 200 N / m; consider that the moving mass block 1 is 20 kg. That is, when the deformation is small, the characteristic frequency of the device is around 1.55 Hz, and when the deformation is large, its characteristic frequency is around 0.5 Hz.

[0115] Example 3

[0116] This embodiment provides a non - linear energy sink device suitable for multi - mode vibration reduction. Except for the following content, the rest is the same as that of Embodiment 1:

[0117] As Figures 12 - 13 shown, two non - linear spring assemblies 3 are installed on each of the four inner walls of the support frame 2 (a total of 8 groups, symmetrically arranged on both sides in the same direction; several groups can be set according to actual situations, and the non - linear spring assemblies 3 arranged along the axial direction of the support frame 2 allow symmetric and / or staggered arrangements). When in a static state, there is a gap between the other end (connection hinge) of the non - linear spring assembly 3 and the moving mass block 1. When the moving distance of the moving mass block 1 does not exceed the gap, the non - linear spring does not provide any restoring force; when the moving mass moves until it contacts and compresses the non - linear spring, the non - linear spring provides a non - linear restoring force. At this time, the non - linear spring on the opposite side does not contact the moving mass block 1 and does not provide a restoring force.

[0118] Example 4

[0119] This embodiment provides a non - linear energy sink device suitable for multi - mode vibration reduction (for unidirectional vibration).

[0120] As Figures 14 - 15 shown, a square moving mass block 1 is arranged on the support frame 2. Universal wheels 5 are arranged on its bottom and two sides perpendicular to the vibration direction, allowing the moving mass block 1 to move back and forth unidirectionally along the moving direction within the support frame 2. In the vibration direction, one non - linear spring assembly 3 is arranged on each side of the moving mass block 1 (a total of 2 groups), and the moving mass block 1 is respectively connected to the non - linear spring assemblies 3 on both sides in a contact connection manner. The moving mass block 1 and the side wall of the support frame 2 in the vibration direction are connected by a damping assembly 4, including a third damper 4 - 3 (parallel to the moving plane of the moving mass block 1, which is a viscous damper, and one of a viscous damper or a magnetorheological damper can be selected according to actual situations), a second connection hinge 4 - 4 connected to the moving mass block 1, and a third connection hinge 4 - 5 connected to the side wall of the support frame 2. One damping assembly 4 is arranged on each side of the moving mass block 1 in the vibration direction (several groups can be arranged only on one side or on both sides according to actual situations). When the moving mass block 1 moves, the viscous damper provides a damping force.

[0121] The mass of the moving mass block 1 is taken as 20 kg, the viscous coefficient of each viscous damper is 0.2 Ns / m, the stiffness coefficient of each non-linear spring assembly 3 is 1800 N / m. In the initial state, the projection length of the linear spring 3-1 along the vibration direction is 0.2 m, and the projection length perpendicular to the vibration direction is 0.2 m, with no initial pre-tension or pre-compression. Then, the moving mass block 1 is forced to deflect 0.199 m from its initial position, and the moving mass block 1 makes a free decay motion under the action of the restoring force and the damping force. The displacement curve of the motion is as Figure 16 shown. By performing time-frequency analysis on the corresponding displacement time history signal, it can be seen that due to the non-linear characteristics, multiple frequency peaks appear (corresponding to the white areas in the time-frequency diagram in Figure 16 ), and the frequency increases with time. Since the displacement decreases with time, that is, the frequency decreases with the increase of displacement or spring deformation, the softening performance of the non-linear energy sink proposed in the present invention is verified.

[0122] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A non-linear energy sink device, which is installed on a flexible structure during use for controlling vibration, is characterized in that, It includes a support frame (2) installed on a flexible structure, a moving mass block (1) disposed within the support frame (2) and allowed to move within the vibration plane of the flexible structure, a non-linear spring assembly (3) disposed between the moving mass block (1) and the support frame (2) and movably connected to the moving mass block (1) and / or the support frame (2) for providing a non-linear restoring force when relative movement occurs between the moving mass block (1) and the support frame (2), and a damping assembly (4) disposed between the mass block and the support frame (2) for providing a damping dissipation capacity when relative movement occurs between the moving mass block (1) and the support frame (2).

2. The non-linear energy trap device according to claim 1, wherein A number of the non-linear spring assemblies (3) are arranged around the moving mass block (1), or a number of the non-linear spring assemblies (3) are arranged along the inner wall of the support frame (2).

3. The non-linear energy well device according to claim 1, characterized in that, Each group of the non-linear spring assemblies (3) includes two identical spring members. One end of the two spring members is connected by an auxiliary connecting member and forms an angle. The other ends of the two spring members are both fixedly connected to the moving mass block (1) or the support frame (2). When the two spring members are squeezed, the connection point thereof deforms along the angle bisector, providing a restoring force opposite to the deformation direction, and the corresponding stiffness coefficient decreases as the deformation increases.

4. A non-linear energy trap device according to claim 3, characterized in that The two spring members are respectively fixedly connected to the moving mass block (1) through fixed connecting members (3-2) and are in contact connection with the support frame (2). Or, the two spring members are respectively connected to the support frame (2) through fixed connecting members (3-2) and are in contact connection with the moving mass block (1). A limiting member (3-4) is provided at the central position of the two fixed connecting members (3-2).

5. The non-linear energy trap device according to claim 4, characterized in that, The angle formed by the two spring members and the auxiliary connecting member is greater than 0° and less than 180°. When the auxiliary connecting member contacts the limiting member (3-4), the axes of the two spring members coincide.

6. A non-linear energy well device according to claim 4, characterized in that, The spring member is a linear spring (3-1). One end of the two linear springs (3-1) is connected by a first connecting hinge (3-3) and forms an angle. The other ends of the two spring members are both fixedly connected to the moving mass block (1) or the support frame (2) through fixed connecting members (3-2).

7. A non-linear energy trap device according to claim 4, characterized in that, The spring member includes a spring telescopic guide rod (3-5), a linear spring (3-1) sleeved on the outer surface of the spring telescopic guide rod (3-5), and a screw rod frame for pre-compressing the linear spring (3-1) and sleeved on the outer surface of the spring telescopic guide rod (3-5). The screw rod frame includes a first end plate (3-7) and a second end plate (3-8) provided at both ends of the linear spring (3-1), and screw rods (3-6) arranged along the circumferential direction of the linear spring (3-1) and fixedly extending out of the first end plate (3-7) and the second end plate (3-8) in sequence. The screw rod (3-6) is fixedly connected to the first end plate (3-7) and is movably connected to the second end plate (3-8). One end of the spring guide rod is connected by a connecting block (3-9) and forms an angle. The other ends of the two spring guide rods are both fixedly connected to the moving mass block (1) or the support frame (2) through fixed connecting members (3-2).

8. The non-linear energy well device according to claim 1, characterized in that The damping component (4) includes a first damping member (4-1) provided at the bottom of the moving mass block (1), and a second damping member (4-2) provided on the upper surface of the support frame (2) and adapted to the first damping member (4-1); the first damping member (4-1) is adapted to the second damping member (4-2). Alternatively, the damping component (4) is a third damping member (4-3) parallel to the movement plane of the moving mass block (1), provided on the side surface of the moving mass block (1) and connected to the moving mass block (1) and the support frame (2).

9. The non-linear energy well device according to claim 1, characterized in that, The support frame (2) is fixed to the flexible structure through an adapter, ensuring that the movement direction of the moving mass block (1) is consistent with the vibration direction of the flexible structure. A universal wheel (5) is provided at the bottom of the moving mass block (1).

10. A design method of the non-linear energy sink device according to any one of claims 1 to 9, characterized in that, It includes the following steps: (S1) Denote the sum of the masses of the moving objects as m. Among them, the moving objects include the moving mass block (1), the nonlinear spring assembly (3), the damping component (4), and the universal wheel (5). (S2) Derive the relationship between the restoring force f and the deformation u of the non-linear spring assembly (3): f u (u); (S3) Deduce the relationship between the stiffness k of the nonlinear spring assembly (3) and the deformation. (S4) Calculate the relationship between the natural vibration frequency ω of the nonlinear energy well and the deformation. (S5) Corresponding to the target frequency range covering the flexible structure and the optimal control amplitude of each order mode, adjust the parameters of the nonlinear spring.

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