CN115263986A - Constant-value quasi-zero stiffness vibration isolation structure and method based on negative stiffness mechanism of two pairs of inclined rods - Google Patents

Abstract

The invention discloses a constant value quasi-zero stiffness vibration isolation structure and a method based on a negative stiffness mechanism of two pairs of inclined rods, wherein brackets are symmetrically arranged on two sides of a fixed plate, a vertical guide rod is arranged in the middle of the fixed plate, a support connecting block is arranged on the upper part of the vertical guide rod, and a vertical guide rod linear bearing connected with the vertical guide rod is arranged on the support connecting block; a vertical spring is arranged on a vertical guide rod between the bottom of the support connecting block and the fixed plate; the left end and the right end of the support connecting block are connected with an inclined rod hinge support; linear bearings are arranged on each bracket at equal intervals, a transverse guide rod is arranged in each linear bearing, and a transverse spring is arranged on each transverse guide rod between the spring clamping plate and the bracket; two pairs of inclined rods are arranged, one end of each inclined rod is hinged with the U-shaped groove through a shaft rod, and the other end of each inclined rod is hinged with an inclined rod hinge support; the bolt penetrates through the hollow pipe and is connected with the connecting hole to fix the load-bearing disc.

Description

Constant-value quasi-zero stiffness vibration isolation structure and method based on negative stiffness mechanism of two pairs of inclined rods

Technical Field

The invention relates to the field of vibration control, in particular to a constant value quasi-zero stiffness vibration isolation structure and method based on a negative stiffness mechanism of two pairs of inclined rods.

Background

A single-pair diagonal rod quasi-zero stiffness model researched in the document [1] is accompanied by three nonlinear stiffness factors, and under the large-amplitude excitation, the transmissibility is bent rightwards, so that the vibration isolation frequency band is reduced; and the parameter design method given by the document is complex (comprising a plurality of inequalities), and is inconvenient to design and apply. The technical scheme in the above document cannot obtain the zero stiffness characteristic that a straight line is near a static balance point, cannot reduce the resonance frequency of a linear vibrator, and has the influence of nonlinear factors; under large excitation conditions, the isolation band is reduced by nonlinear rightward bending.

Document [2] discloses a constant quasi-zero stiffness debugging method based on a single-pair diagonal negative stiffness mechanism-constructed vibration isolator. The application provides another constant value quasi-zero stiffness structure in different structures and different debugging method forms, and the structure and the debugging method are completely different from those of the document [2 ]. The horizontal spring of the document [2] needs a larger rigidity, while the horizontal spring of the present patent application needs a smaller rigidity, and is more suitable for a smaller size space in structure.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a constant value quasi-zero stiffness vibration isolation structure and method based on a negative stiffness mechanism of two pairs of inclined rods.

The purpose of the invention is realized by the following technical scheme:

a constant value quasi-zero stiffness vibration isolation structure based on a negative stiffness mechanism of two pairs of inclined rods comprises a fixing plate, a support, a transverse guide rod, inclined rods, inclined rod hinge supports, support connecting blocks, vertical guide rods, vertical springs, hollow pipes, a load disc and transverse springs; brackets are symmetrically arranged on two sides of the fixed plate, a vertical guide rod is arranged in the middle of the fixed plate, a support connecting block is arranged on the upper portion of the vertical guide rod, and a vertical guide rod linear bearing connected with the vertical guide rod is arranged on the support connecting block; a vertical spring is arranged on a vertical guide rod between the bottom of the support connecting block and the fixed plate;

the left end and the right end of the support connecting block are connected with an inclined rod hinge support which is in a U-shaped structure; two circular through holes are formed in each support at equal intervals, a linear bearing is mounted in each through hole through a clamp spring, a transverse guide rod is mounted in each linear bearing, a U-shaped groove is formed in one end, facing the vertical guide rod, of each transverse guide rod, a spring clamping plate is arranged on the transverse guide rod beside each U-shaped groove, and a transverse spring is mounted on each transverse guide rod between each spring clamping plate and each support;

two inclined rods are symmetrically arranged on two sides of the vertical guide rod respectively, one end of each inclined rod is hinged with the U-shaped groove through a shaft rod, and the other end of each inclined rod is hinged with the inclined rod hinge support;

the support is characterized in that connecting holes are formed in two sides of the support connecting block respectively, hollow pipes are arranged on the connecting holes, and load carrying discs are arranged at the top ends of the hollow pipes and penetrate through the hollow pipes through bolts to be connected and fixed with the connecting holes.

The invention also provides a method for debugging the constant value quasi-zero stiffness vibration isolation structure based on the two pairs of inclined rod negative stiffness mechanisms, which comprises the following steps:

s1, determining the precompression delta of the transverse spring in the initial state according to the parameter condition of the quasi-zero stiffness characteristic ₂ The projection length a of the distance between the hinge points at the two ends of the inclined rod in the horizontal direction and the length of the vertical spring enable the angle delta to be in the initial state ₂ = a, initial state refers to a state where the intersection of two pairs of diagonal rods is in contact with the top end of a vertical spring of free length;

s2, setting the stiffness of two pairs of transverse springs from top to bottom in the constant quasi-zero stiffness vibration isolation structure to be k ₁ Stiffness k of vertical spring ₂ By determining the stiffness k of the transverse spring ₁ Determining the stiffness k of the vertical spring ₂ Building dimensionless parameters

The parameter alpha is more than 0 and less than 0.25;

s3, after the parameters are determined, drawing a force displacement curve f-x, wherein f is the force applied to the load-bearing disc, x is the displacement from the initial position, the force displacement curve is an inclined straight line and has the characteristic of constant quasi-zero rigidity, calculating the rigidity value K, and calculating the initial vibration isolation frequency according to the relation between the vibration isolation masses m on the load-bearing disc

And if the initial vibration isolation frequency does not meet the design requirement, repeating the steps S1 to S3.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the invention provides a constant quasi-zero stiffness vibration isolator constructed by two pairs of inclined rods and a horizontal spring negative stiffness mechanism, which belongs to the field of constant quasi-zero stiffness research and is proposed for the first time.

2. The invention provides a constant value quasi-zero stiffness vibration isolation structure constructed by two pairs of inclined rod negative stiffness mechanisms, and parameter design is carried out, so that force and stiffness expressions obtained are completely different from those of the prior art; at the position of a static balance point, the rigidity is equal to zero and the second derivative of the rigidity is equal to zero, two zero rigidity parameter conditions are obtained, and the constant value quasi-zero rigidity is adjusted according to the parameter conditions as required, so that the method is a brand new debugging method, and is simple in debugging and excellent in precision. In the parametric design (theoretical and technical analysis), the position of the static equilibrium point is the central symmetry state of the two diagonal rods (or the horizontal state of the middle diagonal rod). The two pairs of horizontal springs have the same free length.

3. By the constant value quasi-zero stiffness debugging method, the zero stiffness characteristic that a straight line is near a static balance point can be obtained, the constant value quasi-zero stiffness characteristic in a wider range can be obtained, the resonance frequency of the linear vibrator can be reduced, and no nonlinear factor is attached; compared with a traditional quasi-zero stiffness vibration isolator with weak cubic nonlinear characteristics (non-constant quasi-zero stiffness), under the condition of large-amplitude excitation, the vibration isolation frequency band cannot be reduced due to nonlinear right bending.

4. The invention solves the problem that the traditional quasi-zero stiffness vibration isolator has three-time nonlinearity, and can be used for low-frequency vibration isolation under large excitation amplitude and variable load working conditions. The invention is a constant value quasi-zero rigidity vibration isolation structure, and has infinite static balance positions on the specific application effect.

5. The transverse springs adopted in the invention are more in number, and the transverse springs with smaller size and smaller rigidity can be adopted (the springs are cheaper), so that the manufacturing, application and maintenance costs are reduced. And further a constant quasi-zero stiffness vibration isolation structure with smaller size can be obtained.

6. The invention adopts two pairs of transverse springs, has more design parameters, more selectable parameters and wider application range.

7. The linear stiffness vibration isolation system can be applied to engineering application of low-frequency vibration isolation, and solves the problem that the traditional linear stiffness vibration isolation system needs small dynamic stiffness but generates large static deformation during low-frequency vibration isolation.

Drawings

Fig. 1 is a schematic structural diagram of the constant quasi-zero stiffness vibration isolation structure of the present invention.

Fig. 2a and 2b are front and left side views, respectively, of the stand in the embodiment.

Fig. 3 is a front view of the diagonal member.

Fig. 4a and 4b are a front view and a top view, respectively, of the diagonal bar hinge support.

Fig. 5a and 5b are a front view and a top view, respectively, of the transverse guide.

Fig. 6a and 6b are a front view and a top view, respectively, of the holder connection block.

Fig. 7 and 8 are mechanical schematic diagrams of the constant quasi-zero stiffness vibration isolation structure of the invention after simplification respectively.

Fig. 9a and 9b are schematic diagrams of a stiffness displacement curve and a force displacement curve, respectively.

Reference numerals: 1-fixing plate, 2-bracket, 3-linear bearing, 4-transverse guide rod, 5-spring clamping plate, 6-radial bearing, 7-diagonal rod, 8-diagonal rod hinge support, 9-support connecting block, 10-vertical guide rod, 11-vertical spring, 12-hollow tube, 13-load plate, 14-vertical guide rod linear bearing, 15-transverse spring, 16-thick vertical through hole and 17-thin vertical through hole.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, the present embodiment provides a constant quasi-zero stiffness vibration isolation structure based on a negative stiffness mechanism of two pairs of diagonal rods, which includes a fixing plate 1, a bracket 2, a transverse guide rod 4, a diagonal rod 7, a diagonal rod hinge support 8, a support connection block 9, a vertical guide rod 10, a vertical spring 11, a hollow tube 12, a load-carrying disc 13, and a transverse spring 15;

the two sides of the fixed plate 1 are symmetrically provided with the bracket 2, and the bottom of the bracket 2 is fixedly connected with the fixed plate 1 through a standard part bolt. A vertical guide rod 10 is arranged in the middle of the fixing plate 1, a support connecting block 9 is arranged at the upper part of the vertical guide rod 10, and a vertical guide rod linear bearing 14 connected with the vertical guide rod 10 is arranged on the support connecting block 9; a vertical spring 11 is arranged on a vertical guide rod 10 between the bottom of the support connecting block 9 and the fixed plate 1;

the left end and the right end of the support connecting block 9 are connected with an inclined rod hinge support 8, and the inclined rod hinge support 9 is of a U-shaped structure; two circular through holes are formed in each support 2 at equal intervals, a linear bearing 3 is installed in each through hole through a clamp spring, a transverse guide rod 4 is installed in each linear bearing, specifically, as shown in fig. 2a and fig. 2b, in the embodiment, two circular through holes are formed in each support 2 at equal intervals, the linear bearing 3 of the standard component has the characteristic of a clamp spring groove, and the linear bearing 3 is connected with the support 2 through a clamp spring of the standard component so as to restrain transverse displacement of the linear bearing 3 of the transverse guide rod.

One end of each transverse guide rod 4 facing the vertical guide rod 10 is provided with a U-shaped groove, a spring clamping plate 5 is arranged on the transverse guide rod beside the U-shaped groove, and a transverse spring 15 is arranged on each transverse guide rod 4 between the spring clamping plate 5 and the fixed part;

two inclined rods 7 are symmetrically arranged on two sides of the vertical guide rod 10 respectively, the structures of the inclined rods 7 are shown in figure 4, and two ends of each inclined rod 7 are hinged with an inclined rod hinge support 8 and a U-shaped groove in the transverse guide rod 4 through a radial bearing 6 and a pin shaft respectively. Specifically, a round hole is formed in the end of the diagonal rod 7 (fig. 3), the round hole is matched with an outer ring of the radial bearing (the radial bearing is small, the outer diameter is 5mm, the inner diameter is 2mm, the thickness is about 2mm, most sales platforms are called as miniature bearings), one end of the diagonal rod 7 with the radial bearing is inserted into the transverse guide rod 4 (the right end of fig. 5 b), and then the end of the diagonal rod is inserted into a small hole in the right end of fig. 5a through a pin shaft and simultaneously penetrates through an inner hole of the radial bearing. The diagonal bar 7 and the transverse link 4 are now articulated by means of radial bearings.

Connecting holes are respectively formed in two sides of the support connecting block 9, hollow pipes 12 are arranged on the connecting holes, and a load carrying disc 13 is arranged at the top ends of the hollow pipes 12 and penetrates through the hollow pipes 12 through bolts to be connected with the connecting holes to fix the load carrying disc 13.

Referring to fig. 4a and 4b, the sway bar hinge support 8 in this embodiment is a U-shaped structure, and is composed of a bottom plate and two side plates, the bottom plate is provided with a bolt hole for connecting with the support connection block 9, and the two side plates are symmetrically provided with two shaft holes for hinging with the sway bar.

Referring to fig. 5a and 5b, one end of the transverse guide rod is provided with a U-shaped groove, shaft holes for hinging the inclined rod are symmetrically formed in side plates on two sides of the U-shaped groove, and a groove for mounting the spring clamping plate 5 is formed in the transverse guide rod beside the U-shaped groove.

See fig. 6a and 6b, the both ends of support connecting block are equipped with the bolt hole that is used for hinge support 8 to connect, and the middle part is equipped with the dead eye, and both sides are equipped with the connecting hole that is used for fixed load dish.

In the embodiment, the diagonal rod hinge support 8 is connected with the support connecting block 9 through a stud, the support connecting block 9, the hollow pipe 12, the load disc 13 and the vertical guide rod linear bearing 14 are fastened together through a standard part long bolt, and the vibration isolation mass force borne by the load disc 13 can be transmitted to the two pairs of diagonal rods 7. The transverse guide rod 4 can move in a low friction mode in the horizontal direction after being constrained by the transverse guide rod linear bearing 3. The transverse spring 15 is axially restrained by the spring catch plate 5 and the transverse guide rod linear bearing 3, and the elastic force of the transverse spring can be transmitted to the load disk 13 through the inclined rod 7 to obtain vertical force supporting force, particularly to obtain the vertical negative stiffness characteristic. The vertical spring 11 is constrained by the vertical guide rod 10 and limited in vertical displacement by the vertical guide rod linear bearing 14 and the fixed plate 1, giving the load-carrying disc 13 a load-carrying capacity.

The constant quasi-zero stiffness vibration isolation structure constructed by the two pairs of inclined rod negative stiffness mechanisms is shown in fig. 7 and 8 in a mechanical schematic diagram in an initial state. k is a radical of formula ₂ Is the vertical spring rate, f _h Is an inward elastic force generated by a transverse spring (or a horizontal tension spring), f _{h_u} For the elastic force acting on the transverse spring, f _{h_l} For the elastic force generated by the lateral spring, h is the vertical distance from the initial state to the static equilibrium position, x is the displacement from the initial position, and y is the displacement from the static equilibrium position. a is the projection length of the distance between the hinge points at the two ends of the diagonal bar in the horizontal direction in the initial state; the ratio alpha of the transverse spring stiffness to the vertical spring stiffness; delta refers to the pre-compression length of the lateral spring in the initial state; delta ₂ This refers to the pre-compression length of the transverse spring in the initial state. The vertical distance from the horizontal position of the upper diagonal spring to the horizontal position of the lower diagonal spring is 2d, and the middle position of the 2d is a static balance position.

Firstly, obtaining an expression of the application force f, and carrying out a dimensionless formula (1) on the application force f and the expression thereof in order to analyze wider structural parameter characteristics to obtain the dimensionless application force

Expression, evaluating the expression

For is to

First derivative of (3), obtaining dimensionless stiffness

Formula (2); formula (3) is a parameter expression; in static equilibrium position, for dimensionless rigidity

Respectively taking the first derivative andsecond derivative, the parameter condition of zero stiffness characteristic can be obtained, (4). The static balance position is used as zero displacement, the static balance point is the middle position of 2d in fig. 7, the quasi-zero stiffness characteristic near the static balance point is shown in fig. 7, the quasi-zero stiffness characteristic has a characteristic of constant quasi-zero stiffness (the dynamic stiffness of the vertical spring can be reduced to a state of constant quasi-zero stiffness through a negative stiffness mechanism of the double diagonal rods, and meanwhile, higher static stiffness is kept to bear load), particularly, the constant quasi-zero stiffness can be adjusted as required, and the dotted lines in fig. 9a and 9b show that the vibration isolator has the capability of constant quasi-zero stiffness.

The inclined rod 7 and the transverse spring 15 generate vertical negative stiffness, which is called a double-diagonal negative stiffness mechanism, the double-diagonal negative stiffness mechanism is connected with the positive stiffness of the vertical spring 11 in parallel, and the constant-value quasi-zero stiffness characteristic can be vertically obtained near a static balance point (the static balance point is the position where the upper and lower diagonal rods are vertically symmetrical) according to the debugging method of the formula (5).

The constant quasi-zero stiffness (shown in FIG. 8) is adjusted such that the ratio α of the stiffness of the transverse spring 15 to the stiffness of the vertical spring 11 is selected to satisfy 0 < α < 0.25, and the pre-compression length δ of the lower pair of transverse springs in the transverse spring 15 is set to be equal to or smaller than 0.25 ₂ Equal to the horizontal length a between the two hinge points of the lower diagonal of the diagonal 7 in the initial condition. If the two conditions are met, the constant quasi-zero stiffness characteristic can be obtained.

The specific debugging method comprises the following steps:

s1, determining the precompression delta of the transverse spring in the initial state according to the parameter condition of the quasi-zero stiffness characteristic ₂ The projection length a of the distance between the hinge points at the two ends of the inclined rod in the horizontal direction and the length of the vertical spring enable the angle delta to be in the initial state ₂ = a, initial state refers to a state where the intersection of two pairs of diagonal rods is in contact with the top end of a vertical spring of free length;

s2, setting the stiffness of two pairs of transverse springs from top to bottom in the constant value quasi-zero stiffness vibration isolation structure to be k respectively ₁ 、k ₁ Stiffness k of vertical spring ₂ By determining the stiffness k of the transverse spring ₁ Determining the stiffness k of the vertical spring ₂ Building dimensionless parameters

The parameter alpha is more than 0 and less than 0.25;

s3, after the parameters are determined, drawing a force displacement curve f-x, wherein f is the force applied to the load-bearing disc, x is the displacement from the initial position, the force displacement curve is an inclined straight line and has the characteristic of constant quasi-zero rigidity, calculating the rigidity value K, and calculating the initial vibration isolation frequency according to the relation between the vibration isolation masses m on the load-bearing disc

And if the initial vibration isolation frequency does not meet the design requirement, repeating the steps S1 to S3.

The invention finally tests the vibration isolator with the constant quasi-zero stiffness characteristic, solves the problem that the traditional quasi-zero stiffness vibration isolator has three-time nonlinearity, and can be used for low-frequency vibration isolation under large excitation amplitude and variable load working conditions. The traditional cubic nonlinear stiffness vibration isolator only has one static balance position, while the invention is a constant value quasi-zero stiffness vibration isolator and has infinite static balance positions.

The present invention is not limited to the embodiments described above. The foregoing description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above specific embodiments are merely illustrative and not restrictive. Those skilled in the art can make many changes and modifications to the invention without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (2)

1. A constant quasi-zero stiffness vibration isolation structure based on a negative stiffness mechanism of two pairs of inclined rods is characterized by comprising a fixing plate, a bracket, a transverse guide rod, inclined rods, inclined rod hinge supports, support connecting blocks, a vertical guide rod, a vertical spring, a hollow tube, a load disc and a transverse spring; brackets are symmetrically arranged on two sides of the fixed plate, a vertical guide rod is arranged in the middle of the fixed plate, a support connecting block is arranged on the upper portion of the vertical guide rod, and a vertical guide rod linear bearing connected with the vertical guide rod is arranged on the support connecting block; a vertical spring is arranged on a vertical guide rod between the bottom of the support connecting block and the fixed plate;

the left end and the right end of the support connecting block are connected with an inclined rod hinge support which is of a U-shaped structure; two circular through holes are formed in each support at equal intervals, a linear bearing is mounted in each through hole through a clamp spring, a transverse guide rod is mounted in each linear bearing, a U-shaped groove is formed in one end, facing the vertical guide rod, of each transverse guide rod, a spring clamping plate is arranged on the transverse guide rod beside each U-shaped groove, and a transverse spring is mounted on each transverse guide rod between each spring clamping plate and each support;

two inclined rods are symmetrically arranged on two sides of the vertical guide rod respectively, one end of each inclined rod is hinged with the U-shaped groove through a shaft rod, and the other end of each inclined rod is hinged with the inclined rod hinge support;

the support is characterized in that connecting holes are formed in two sides of the support connecting block respectively, hollow pipes are arranged on the connecting holes, and load carrying discs are arranged at the top ends of the hollow pipes and penetrate through the hollow pipes through bolts to be connected and fixed with the connecting holes.

2. A method for debugging a constant quasi-zero stiffness vibration isolation structure based on the two pairs of diagonal rod negative stiffness mechanisms of claim 1, comprising:

s1, determining the precompression delta of the transverse spring in the initial state according to the parameter condition of the quasi-zero stiffness characteristic ₂ The projection length a of the distance between the hinged points at the two ends of the inclined rod in the horizontal direction and the length of the vertical spring are used for ensuring that the distance is delta under the initial state ₂ = a, initial state refers to a state where the intersection of two pairs of diagonal rods is in contact with the top end of a vertical spring of free length;

s2, setting the stiffness of two pairs of transverse springs from top to bottom in the constant value quasi-zero stiffness vibration isolation structure to be k ₁ Stiffness k of vertical spring ₂ By determining the stiffness k of the transverse spring ₁ Determining the stiffness k of the vertical spring ₂ Building dimensionless parameters

The parameter alpha is more than 0 and less than 0.25;

s3, after the parameters are determined, drawing a force displacement curve f-x, wherein f is the force applied to the load-bearing disc, x is the displacement from the initial position, the force displacement curve is an inclined straight line and has the characteristic of constant quasi-zero rigidity, calculating the rigidity value K, and calculating the initial vibration isolation frequency according to the relation between the vibration isolation masses m on the load-bearing disc

And if the initial vibration isolation frequency does not meet the design requirement, repeating the steps S1 to S3.

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