CN211145203U - Periodic structure with bistable nonlinear energy trap - Google Patents

Abstract

The utility model relates to a periodic structure with bistable nonlinear energy trap (NES), including the board base member, arrange according to periodicity or quasi-periodicity and set up bistable NES of m row n row on the base member, wherein bistable NES comprises two springs, a attenuator and a little mass block. Each spring is fixedly connected with the plate base body through a rigid fixing end. It is also possible to arrange m rows and n columns of scatterer vibrators stacked by a soft material layer and a hard material layer on the plate in a protruding manner, and then arrange bistable NES on each vibrator. Each spring is now held together with the hard material by a rigid fixing end. By setting the bistable NES, a nonlinear energy trap and a negative stiffness energy trap are coupled in the structure and are designed into a sub-wavelength periodic structure. When transient impact acts on the periodic structure, the specific steady state transition in the bistable NES can improve the action range of high-efficiency target energy transmission, and can quickly transmit transient energy in the matrix to the NES so as to quickly attenuate matrix vibration. Compared with the traditional vibration isolation and absorption structure, the periodic structure with the bistable nonlinear energy trap has the advantages of small additional mass, wide vibration suppression frequency band, capability of finishing directional target energy transfer, high reliability, strong robustness, no need of external energy supply and the like, and has wide application prospect in the field of impact and shock wave protection.

Description

A periodic structure with a bistable nonlinear energy well

technical field

The utility model relates to a periodic structure, in particular to a periodic structure with a bistable nonlinear energy well. It belongs to the technical field of vibration, shock and impact protection material manufacturing.

Background technique

Periodic structure, also known as phononic crystal, the concept of phononic crystal is derived from photonic crystal. In phononic crystal, materials with different elastic constants and densities are arranged periodically, and the materials that are connected to each other are called matrix. Connected materials are called scatterers. Vibration usually propagates in periodic structures in the form of elastic waves, and the elastic wave band gap can also be called the vibration band gap. The elastic wave bandgap of the periodic structure can be used for vibration reduction. On the one hand, it can provide a vibration-free processing environment within a certain frequency range for high-precision processing systems to ensure high processing accuracy requirements; on the other hand, it can provide special precision instruments or equipment. Vibration-free working environment within a certain frequency range, improve working accuracy and reliability, and prolong its service life.

The concept of nonlinear energy sink (NES) was proposed around 2000, which was developed on the basis of dynamic vibration absorbers. Linear dynamic vibration absorbers need to resonate with the main structure to achieve vibration reduction, which makes them only applicable to equipment with small changes in vibration frequency. Weak nonlinear dynamic vibration absorber can broaden the vibration reduction frequency band to a certain extent, but it still can only absorb vibration energy from a certain frequency band. Semi-active, active and hybrid vibration absorber designs enable dynamic vibration absorbers to have frequency tracking or multi-band vibration reduction capabilities. However, these solutions require additional energy devices and controllers, so their applications are very limited. Nonlinear energy well is a kind of vibration absorber with pure nonlinear stiffness, which has attracted the attention of a large number of researchers due to its advantages of broadband vibration absorption and light weight. The unique steady-state transition in bistable NES can improve the range of efficient target energy transfer. The research on the NES structure and its TET mechanism has laid a theoretical foundation for the design of metamaterial structures with shock wave control properties, and is expected to provide technical support for shock and shock wave protection of important equipment such as ships and armor.

SUMMARY OF THE INVENTION

Technical problem: The purpose of this utility model is to provide a periodic structure with a bistable nonlinear energy well, by periodically setting the bistable nonlinear energy well on the base plate, so as to realize the suppression of the transient impact energy and absorption.

Technical solution: The present utility model is a periodic structure with a bistable nonlinear energy well. The periodic structure includes a plate base, and m rows of convexly arranged on the plate base are periodically or quasi-periodically arranged. A bistable NES of n columns; where the bistable NES consists of two springs, a damper, and a small mass; each spring is fixed to the plate base by a rigid fixed end; the axis of the rigid fixed end is perpendicular to the plate On the surface of the base body, one end of the spring is connected with the rigid fixed end, and the other end is connected with the small mass block; one end of the damper is connected with the small mass block, and the other end is connected with the surface of the plate base body.

The angle between the axis of the spring and the horizontal line is θ. When |θ| is an angle greater than 0°, the two springs are at a free length l ₀ , and the structure as a whole is in a balanced state; when θ=0° , the length of the two springs is l, l<l ₀ , the two springs are in a compressed state at this time, and the overall structure is in an unbalanced state.

On the board base, firstly, m rows and n columns of vibrators are arranged on the board, which are stacked by a layer of soft material and a layer of hard material, and then a bistable NES is set on each vibrator, and is fixed by rigid fixed ends. Knot.

The bistable NES and the scatterer vibrator formed by stacking soft materials and hard materials provided by the protrusions are arranged on one side or two sides on the board substrate.

The small mass of the bistable NES is cylindrical, cuboid or spherical; the shape of the rigid fixed end is cylindrical or cuboid.

The soft material and the hard material have the same or different shapes, and are cylindrical or cuboid.

The thicknesses of the small mass of the bistable NES, the soft material and the hard material of the plate substrate are the same or different.

The smallest repeating unit of the bistable NES with m rows and n columns forming a periodic structure is called a unit cell, and the arrangement shape between the unit cells is a square, an equilateral triangle or other polygons.

The material of the board substrate is metal, concrete, ceramic, fiber-reinforced composite material or rubber or polyurethane material.

The soft material is a polymer material such as rubber or polyurethane; the hard material and the material of the small mass of the bistable NES are metal, concrete, ceramic or fiber-reinforced composite material.

Beneficial effect: Compared with the prior art, the utility model has the following advantages:

1) Compared with other impact energy absorbing devices, the periodic structure is small in size and low in cost. At the same time, it is convenient to manufacture and facilitate standardized production.

2) Large-scale machinery often has broadband characteristics in complex dynamic environments. In the past, the vibration control of broadband structures mainly applied active and passive integrated vibration isolation technology. However, for oscillators with broadband characteristics

Dynamic control mechanism, active and passive integrated vibration control technology is difficult to adapt to complex working conditions. The unique steady-state transition in bistable NES can improve the range of efficient target energy transfer. At the same time, it has the advantages of small additional mass, wide vibration suppression frequency band, directional target energy transfer, high reliability, strong robustness, and no external energy supply.

Description of drawings

Fig. 1 is the periodic structure diagram that the small mass of the utility model bistable NES is spherical;

Fig. 2 is the unit cell diagram of the periodic structure of Fig. 1 of the utility model;

Fig. 3 is the periodic structure diagram that the small mass block of the utility model bistable NES is a cuboid;

Fig. 4 is the periodic structure diagram in which the small mass of the bistable NES with the double-layer arrangement of the utility model is spherical;

5 is a top view of the periodic structure of the present utility model arranged according to an equilateral triangle;

Fig. 6 is the periodic structure diagram that the utility model is also provided with the cylindrical oscillator between the base plate and the bistable NES;

Fig. 7 is the unit cell diagram of the periodic structure of Fig. 6 of the utility model;

FIG. 8 is a schematic plan view of the bistable NES of the present invention.

In the figure: plate base 1, bistable nonlinear energy well 2, spring 2-1, damper 2-2, small mass 2-3, rigid fixed end 3, soft material layer 4, hard material layer 5.

Detailed ways

The implementation method of the present invention is as follows:

The periodic structure includes a plate base, and bistable NESs with m rows and n columns arranged periodically or quasi-periodically on the plate base and convexly arranged; wherein the bistable NES consists of two springs, a damper and It consists of a small mass; each spring is fixed with the plate base through the rigid fixed end; the axis of the rigid fixed end is perpendicular to the surface of the plate base, one end of the spring is connected with the rigid fixed end, and the other end is connected with the small mass; damper One end is connected to the small mass, and the other end is connected to the surface of the plate base.

The bistable nonlinear energy wells with m rows and n columns are arranged periodically or quasi-periodically on the base plate; a layer of soft material and A vibrator made of stacked hard materials. Bistable nonlinear energy wells and oscillators can be arranged on one or both sides of the base plate. The shape of the arrangement between the individual unit cells of the periodic structure can be square, triangle or other polygons. The material of the board substrate can be metal, concrete, ceramics, fiber-reinforced composite materials, or materials such as rubber and polyurethane. The soft material can be a polymer material such as rubber or polyurethane. The material of the hard material and the small mass of the bistable nonlinear energy trap can be metal, concrete, ceramic or fiber reinforced composite material.

Below in conjunction with accompanying drawing, the utility model is described in further detail by embodiment:

Example 1:

As shown in FIGS. 1 , 2 and 8 , this embodiment is a periodic structure with a bistable nonlinear energy well. In Fig. 1, a bistable nonlinear energy well with m rows and n columns is set on one side of the base plate, and a square lattice arrangement is adopted between each unit cell, and the lattice constant is set as a ₁ . The small mass of the bistable NES is spherical, and the bistable nonlinear energy well in Fig. 2 consists of a spring, a damper and a small mass.

Example 2:

As shown in FIGS. 3 and 8 , this embodiment is a periodic structure with a bistable nonlinear energy well. In Fig. 3, a bistable nonlinear energy well with m rows and n columns is set on one side of the plate substrate, and a square lattice arrangement is adopted between each unit cell, and the lattice constant is set as a ₁ . The small mass of the bistable NES is cuboid. The bistable nonlinear energy well consists of springs, dampers and a small mass.

Example 3:

As shown in FIGS. 4 and 8 , this embodiment is a periodic structure with a bistable nonlinear energy well. In Fig. 4, m rows and n columns of bistable nonlinear energy wells are arranged on both sides of the plate substrate, and a square lattice arrangement is adopted between each unit cell, and the lattice constant is set to a ₁ . The small mass of the bistable NES is spherical. The bistable nonlinear energy well consists of springs, dampers and a small mass.

Example 4:

As shown in FIGS. 2 , 5 and 8 , this embodiment is a periodic structure with a bistable nonlinear energy well. In Fig. 5, a bistable nonlinear energy well with m rows and n columns is set up on one side of the plate base. The equilateral triangular lattice is arranged between the unit cells, and the lattice constant is set to a ₂ . The small mass of the bistable NES is spherical. The bistable nonlinear energy well consists of springs, dampers and a small mass.

Example 5:

As shown in FIGS. 6 , 7 and 8 , this embodiment is a periodic structure with a bistable nonlinear energy well. Fig. 6 A vibrator consisting of a layer of soft material and hard material stacked with m rows and n columns is set up on one side of the plate base, and a bistable nonlinear energy well is set on each vibrator. A square lattice arrangement is used, and the lattice constant is set to a ₁ . The shape of the oscillator is cylindrical and the small mass of the bistable NES is spherical. The bistable nonlinear energy well consists of springs, dampers and a small mass.

By setting up such a bistable NES, a nonlinear energy well and a negative stiffness energy well are coupled in the structure and designed as a subwavelength periodic structure. The unique steady-state transition in bistable NES can improve the range of efficient target energy transfer, and the transient impact energy in the structure will be localized to the nonlinear additional mass through passively controlled space transfer, thereby effectively suppressing the matrix structure. transient vibration. The research on the NES structure and its TET mechanism has laid a theoretical foundation for the design of metamaterial structures with shock wave control properties, and is expected to provide technical support for shock and shock wave protection of important equipment such as ships and armor.

The above is only the preferred embodiment of the present utility model, it should be pointed out that: for those skilled in the art, without departing from the principle of the present utility model, several improvements and modifications can also be made. These improvements and Retouching should also be regarded as the protection scope of the present invention.

Claims (10)

1. A periodic structure with bistable nonlinear energy traps, characterized in that the periodic structure comprises a plate matrix (1), and m rows and n columns of bistable NES (2) arranged in a periodic or quasi-periodic arrangement on the plate matrix (1) in a raised manner; wherein the bistable NES (2) consists of two springs (2-1), a damper (2-2) and a small mass block (2-3); each spring (2-1) is fixedly connected with the plate base body (1) through a rigid fixing end (3); the axis of the rigid fixed end (3) is vertical to the surface of the plate base body (1), one end of the spring (2-1) is connected with the rigid fixed end (3), and the other end of the spring is connected with the small mass block (2-3); one end of the damper (2-2) is connected with the small mass block (2-3), and the other end is connected with the surface of the plate base body (1).

2. A periodic structure with a bistable nonlinear energy trap as claimed in claim 1 wherein the angle between the axis of the springs (2-1) and the horizontal is θ, and when | θ | is some angle greater than 0 °, the springs (2-1) are at free length l₀At the moment, the whole structure is in a balanced state; when theta is equal to 0 DEG, the length of the two springs (2-1) is l, and l is less than l₀At the moment, the two springs (2-1) are in a compressed state, and the whole structure is in an unbalanced state.

3. The periodic structure with bistable nonlinear energy traps according to claim 1, characterized in that m rows and n columns of vibrators made of a soft material (4) and a hard material (5) are arranged on the plate substrate (1) in a stacked manner, wherein m rows and n columns of vibrators are arranged on the plate substrate in a protruding manner, and bistable NES (2) is arranged on each vibrator and is fixed through a rigid fixing end (3).

4. A periodic structure with bistable nonlinear energy traps according to claim 3, characterized in that the bistable NES (2) and convexly arranged scatterer vibrator stacked of soft (4) and hard (5) materials is arranged one-sided or two-sided on the plate matrix (1).

5. A periodic structure with bistable nonlinear energy traps according to claim 1, characterized in that the small masses (2-3) of the bistable NES (2) are cylindrical, cuboid or spherical; the rigid fixing end (3) is cylindrical or cuboid.

6. A periodic structure with bistable nonlinear energy traps according to claim 3, characterized in that the soft material (4) and the hard material (5) have the same or different shapes and are cylindrical or rectangular parallelepiped.

7. Periodic structure with bistable nonlinear energy wells according to claim 1 characterized in that the plate matrix (1), the small masses (2-3) of the bistable NES (2) and the thicknesses of soft (4) and hard (5) materials are the same or different.

8. The periodic structure with bistable nonlinear energy traps as claimed in claim 1, characterized in that said m rows and n columns of bistable NES (2) form the smallest repeating unit of periodic structure called unit cell, and the arrangement shape between unit cells is polygon.

9. Periodic structure with bistable nonlinear energy trap according to claim 1, characterized in that the material of the plate matrix (1) is metal, concrete, ceramic, fiber reinforced composite or rubber or polyurethane material.

10. A periodic structure with bistable nonlinear energy traps according to claim 3, characterized in that the soft material (4) is a polymer material such as rubber or polyurethane; the material of the hard material (5) and the small mass (2-3) of the bistable NES (2) is metal, concrete, ceramic or fibre-reinforced composite material.

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