A three-dimensional cell-type vibration absorber for suppressing time-varying chatter in robot milling and its design method

Abstract

The present invention belongs to the technical field of vibration control in robot milling, specifically a three-dimensional crystalline cell vibration absorber and its design method for suppressing time-varying vibration in robot milling. The vibration absorber includes a plurality of magnetic balls, a plurality of magnetorheological elastomers, a magnetic block, an electromagnetic coil, an upper and lower wall, and four side walls; the upper and lower walls and the four side walls form a cubic structure, the electromagnetic coil is sleeved on the outer wall of the four side walls, the magnetic block is sleeved on the outer wall of the electromagnetic coil, and is connected to the upper and lower walls; the three-dimensional crystalline cell vibration absorber is a centrally symmetrical structure; a plurality of magnetic balls are arranged in the cubic structure in the form of a body-centered cubic structure, and the inner wall of the cubic structure is connected to the magnetic balls, and the magnetic ball at the center of the body is connected to the magnetic balls at the eight vertex corners through the magnetorheological elastomer. The entire structure of the present invention has three-dimensional symmetry, so that it can remain stable under any rotation posture of the robot, and can suppress the modes of the robot in different directions and frequencies, and the suppression effect is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of robot milling vibration control, and in particular relates to a three-dimensional cellular vibration absorber for suppressing time-varying chatter in robot milling and a design method thereof. Background Art

[0002] As modern manufacturing demands increased processing of large components, robotic milling has gained widespread application in complex parts processing due to its high efficiency, low cost, and versatility. However, as robotic milling technology has developed, its limitations have become increasingly apparent, one of which is the low-frequency vibration caused by low structural stiffness.

[0003] Adding vibration absorbers is a common method for suppressing low-frequency chatter in robotic milling. Zhang et al. (Mechanical Systems and Signal Processing 2023;200:110506) designed a parallel MTMD system to suppress the forced vibration of a parallel machining robot in both feed directions. By using small polymer springs and viscous fluid damping within a mass block to form the MTMD system, broadband vibration suppression was achieved within a confined space. Yuan et al. (Mechanical Systems and Signal Processing 2019;117:221-37) proposed developing a semi-active vibration absorber using magnetorheological elastomer (MRE). MRE is a new type of magnetically controlled material whose internal magnetic particles undergo structural changes under the stimulation of an external magnetic field, resulting in changes in the material's mechanical properties. The designed MRE vibration absorber can cover chatter frequency variations of 7-20 Hz.

[0004] When a robot performs milling, its posture-dependent characteristics cause the low-frequency chatter mode to have time-varying properties. This time-varying property is reflected not only in frequency but also in direction. Currently, there are few studies on chatter suppression devices for robot milling that consider both modal direction and frequency time-varying properties, and most studies can only suppress two directions. In order to effectively suppress the time-varying chatter of robot milling, higher requirements are placed on vibration suppression equipment: First, the direction and frequency of the chatter are both time-varying, requiring the development of multi-directional vibration suppression equipment that can change frequency or has broadband vibration suppression characteristics. Second, the robot's posture constantly changes during the processing process, especially when machining large parts, requiring vibration suppression equipment to maintain its original vibration suppression capabilities under any rotational posture. Summary of the Invention

[0005] The purpose of the present invention is to provide a three-dimensional cellular vibration absorber and a design method thereof for suppressing time-varying chatter of robot milling, so as to suppress the modes of the robot in different directions and frequencies and solve the problem of time-varying chatter.

[0006] To achieve the above objectives, the present invention provides a three-dimensional lattice vibration absorber for suppressing time-varying chatter in robot milling, comprising a plurality of magnetically conductive balls, a plurality of magnetorheological elastomers, a magnetic conductive block, an electromagnetic coil, upper and lower walls, and four side walls; the upper and lower walls and the four side walls form a cubic structure, the electromagnetic coil is sleeved on the outer walls of the four side walls, the magnetic conductive block is sleeved on the outer wall of the electromagnetic coil and connected to the upper and lower walls; the three-dimensional lattice vibration absorber is a centrally symmetrical structure;

[0007] Several magnetic balls are arranged in the cubic structure in the form of a body-centered cubic structure, and the inner wall of the cubic structure is connected to the magnetic balls. The magnetic ball located at the center of the body is connected to the magnetic balls located at the eight vertex corners through the magnetorheological elastomer.

[0008] Furthermore, the magnetorheological elastomer is obtained by mixing carbonyl iron powder, silicone rubber and dimethyl silicone oil in a mass ratio of (1-3): (0.5-1.5): 1 and curing.

[0009] Furthermore, the magnetorheological elastomers used to connect the magnetic conductive balls in the same layer are connected to each other through the magnetorheological elastomer to form a network structure.

[0010] Furthermore, the magnetic conductive ball is connected to the magnetorheological elastomer by bonding, and the contact surface is in contact with the arc surface of the magnetic conductive ball;

[0011] The magnetic conductive ball is connected to the inner wall of the cubic structure by welding.

[0012] Furthermore, the material of the magnetic conductive balls and magnetic conductive blocks is No. 10 steel;

[0013] The side wall is made of non-magnetic aluminum alloy, and the upper and lower walls are made of magnetic material.

[0014] The present invention further provides a method for designing a three-dimensional unit cell vibration absorber as described in any one of the above, comprising the following steps:

[0015] S1. Determine the target vibration suppression frequency;

[0016] S2. Preliminary determination of the side length L of the vibration absorber and the number of turns N of the electromagnetic coil coil and an applied current I; the side length L of the vibration absorber refers to the side length of the body-centered cubic structure composed of the magnetic sphere and the magnetorheological elastomer in the cubic structure;

[0017] S3. Preliminarily give the initial values ​​of n and γ, and calculate the thickness h and diameter d of the magnetorheological elastomer according to the following formula MRE And the diameter d0 of the magnetic sphere:

[0018] F a =Ncoil I=φR a

[0019] φ=BS

[0020] R a =R1+R2+R MRE

[0021]

[0022] 2πd MRE 2 =γπd0 2

[0023] Where n represents the number of body-centered cubic structure layers contained in each side of the vibration absorber, γ represents the ratio of the total contact area of ​​the eight magnetorheological elastomers and the magnetic sphere to the surface area of ​​the magnetic sphere; F a is the magnetomotive force, φ is the total magnetic flux, B is the magnetic induction intensity, S is the area through which the magnetic field passes, R a is the total magnetic resistance; μ0=4π×10 -7 T·m / A is the vacuum permeability; μ MRE ≈2, is the magnetic permeability of the magnetorheological elastomer;

[0024] S4. Calculate the natural frequency based on the dynamic model according to the design parameters preliminarily determined above;

[0025] S5. Determine whether the natural frequency meets the requirements. If so, the parameters of steps S2 and S3 are the design parameters of the vibration absorber. If not, repeat steps S2-S5 until the optimized vibration absorber design parameters are obtained.

[0026] Furthermore, when determining the side length L, first select a value within 80 to 120 mm, and the number of turns N coil And the current I first flows through N coil The value is within the range of I≤7kA.

[0027] Furthermore, the value range of γ is 0.25 to 0.6; when determining the initial value of n, it is first determined within the range of n≤5;

[0028] And / or, the target vibration suppression frequency is 10 to 30 Hz.

[0029] Furthermore, the method for constructing the kinetic model includes:

[0030] (1) Establish the mass matrix of the n-layer three-dimensional unit cell vibration absorber:

[0031]

[0032] in, ρ and d0 represent the density and diameter of the magnetic sphere, respectively;

[0033] (2) Establish the stiffness matrix K = [Λ ij ] N×N , where Λ ij is a 3×3 matrix, representing the interaction between the i-th magnetic conductive ball and the j-th magnetic conductive ball, Λ ij =Λ ji T ;

[0034] (3) Fill the stiffness matrix K according to the different positions of the magnetic balls to obtain the characteristic equation of the multi-degree-of-freedom system:

[0035] det(K-ω 2 M)=0

[0036] Solving the above equations, we get 3N positive real roots, corresponding to the 3N natural angular frequencies of the system, that is, ω1≤ω2≤...≤ω 3N ;

[0037] (4) The three-dimensional unit cell vibration absorber is considered to have the same N-order frequency in three directions, which can be expressed as:

[0038] f X =f Y =f Z =[f1,...,f N ]

[0039] The natural frequency

[0040] Furthermore, different Λ ij The expression is as follows:

[0041]

[0042]

[0043] Among them, Proj represents the interactive projection relationship, D ij is the direction matrix, indicating the direction of interaction, θ and α are the angles between the body diagonal and the side length, and between the face diagonal and the side length of the primitive, respectively; represents the dot product of matrices, is the stiffness of a single cylindrical MRE; E is the magnetocompression modulus of the cylindrical MRE.

[0044] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0045] 1. The three-dimensional unit cell vibration absorber provided by the present invention addresses the time-varying characteristics of flutter by stacking magnetic spheres in a body-centered cubic form to form a unit cell, which serves as the effective mass of the vibration absorber. The magnetic spheres are connected by a mesh MRE, which provides adjustable stiffness for the vibration absorber. The entire structure has three-dimensional symmetry, allowing it to remain stable under any rotational posture of the robot.

[0046] 2. The present invention establishes a dynamic model of a three-dimensional lattice vibration absorber. Based on the dynamic model, the influence of various parameters of the vibration absorber on the natural frequency is analyzed, and the design basis for developing the vibration absorber is obtained, so that the target vibration absorber can be quickly and reasonably designed according to the target vibration suppression frequency to solve the time-varying characteristics of the flutter. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall process of design and application of the three-dimensional unit cell vibration absorber of the present invention.

[0048] Figure 2 Schematic diagram of the structure of the three-dimensional unit cell vibration absorber of the present invention.

[0049] Figure 3 Schematic diagram of the relative position relationship of the balls in the simplified model of the three-dimensional unit cell vibration absorber.

[0050] Figure 4 Schematic diagram of the simplified magnetic circuit model of a three-dimensional cell vibration absorber.

[0051] Figure 5 These are the first-order frequency simulation results of the system under different parameters.

[0052] Figure 6 Schematic diagram of the design process of a three-dimensional cell vibration absorber.

[0053] Figure 7 This is a physical picture of the designed vibration absorber prototype.

[0054] Figure 8 Modal testing of the robot.

[0055] Figure 9 For robots Figure 8 Direct and crossover frequency responses of the front and rear ends of the additional absorber in mid-stance 2.

[0056] Figure 10 For robots Figure 8 Direct and crossover frequency responses of the front and rear ends of the additional vibration absorbers in mid-stance 4. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0058] In view of the shortcomings of the prior art in related aspects, the present invention designs a three-dimensional lattice vibration absorber for suppressing the time-varying vibration of the robot. Figure 1 The specific implementation process is demonstrated: (1) Design of a three-dimensional unit cell vibration absorber structure: To address the time-varying characteristics of flutter, magnetic spheres 1 are stacked in a body-centered cubic structure to form a unit cell, which serves as the effective mass of the vibration absorber. The magnetic spheres are bonded together using a mesh MRE 2, which provides adjustable stiffness for the vibration absorber. The entire structure has three-dimensional symmetry, allowing it to remain stable even under arbitrary rotational postures of the robot.

[0059] (2) Perform dynamic modeling of a three-dimensional lattice vibration absorber: simplify the system into a multi-degree-of-freedom system and establish a dynamic model of the system; then, based on this simulation, the changing law of the natural frequency under various parameters is obtained to obtain the criteria for designing a vibration absorber prototype.

[0060] (3) Design the parameters of a three-dimensional lattice vibration absorber and conduct application case verification: Develop a vibration absorber prototype based on the design criteria and vibration suppression objectives, attach the vibration absorber prototype to the robot and conduct dynamic compliance suppression experiments to verify the suppression effect of the prototype.

[0061] The following is a detailed description through specific implementation methods.

[0062] Example 1: Structural design of a three-dimensional unit cell vibration absorber

[0063] Figure 2The structure of a three-dimensional unit cell vibration absorber is shown, which consists of a magnetic block 1, a mesh MRE 2, a magnetic ball 3, a coil 4, four side walls 5 and upper and lower walls 6. Among them, the magnetorheological elastomer 2 is a magnetically driven intelligent material that can achieve changes in its own stiffness by changing the external driving magnetic field. The magnetic balls 3 are stacked in the form of a body-centered cubic structure to form a unit cell, providing the effective mass of the vibration absorber. Each unit cell contains a magnetic ball 3 at the center of the body and eight magnetic balls 3 at the top corners, wherein the body-center magnetic ball 3 and each magnetic ball 3 at the top corner are connected by the columnar part of the mesh MRE 2 (hereinafter referred to as columnar MRE unless otherwise specified). In order to ensure the three-dimensional symmetry of the entire structure, the side walls 5 and the upper and lower walls 6 are designed as walls with spheres, so that the connection between the magnetic balls 3 at the boundary and the wall is consistent with the connection between the magnetic balls 3 inside the unit cell. To facilitate the laying of MRE 2 and magnetic balls 3, the columnar MREs of each layer are connected to form a mesh, where the columnar parts provide variable stiffness for the structure, and the remaining parts only serve as connections.

[0064] The overall structure exhibits three-dimensional symmetry, with identical stiffness and mass in all three orthogonal directions. Each magnetic sphere 3 is supported by eight surrounding columnar MREs 2. The contact surfaces between the magnetic spheres 3 and the columnar MREs 2 are curved to ensure support stability, allowing the absorber to maintain its vibration damping capabilities even after rotation at any angle.

[0065] The coil 4 is encased in the outer wall of the vibration absorber. The upper and lower walls 6 are made of a magnetically conductive material, while the side wall 5 is constructed of a non-magnetic aluminum alloy. The magnetic block 1 is connected to the upper and lower walls 6 of the vibration absorber. The magnetic field passes through the MRE 2 between the magnetic spheres 3 inside the vibration absorber, then returns to its starting point via the upper and lower walls 6 and the magnetic block 1, forming a closed magnetic circuit. During operation, the stiffness of the columnar MRE is adjusted by varying the driving current of the magnetic field, thereby achieving the variable frequency function of the vibration absorber.

[0066] Example 2: Construction of kinetic model

[0067] The n-layer three-dimensional unit cell vibration absorber has n 3 primitives (including the primitives formed by the magnetic balls on the inner wall of the three-dimensional unit cell absorber), containing N = n 3 +(n-1) 3 There are three magnetic balls (excluding the magnetic balls on the inner wall of the three-dimensional unit cell vibration absorber). Each magnetic ball has three degrees of freedom in the X, Y, and Z directions. The system can be regarded as a multi-degree-of-freedom system with 3N degrees of freedom, such as Figure 3 As shown ( Figure 3The magnetic spheres on the inner wall of the three-dimensional unit cell absorber are not included. Ignoring the influence of gravity, the static equilibrium position of the system is taken as the origin of the generalized coordinate system, and all magnetorheological elastomers (MREs) in the system are in their original state. The mass of each magnetic sphere in the X, Y, and Z directions is the same, m. The mass matrix of the system is:

[0068]

[0069] in, ρ and d0 represent the density and diameter of the magnetic sphere, respectively.

[0070] According to the D'Alembert principle, the stiffness matrix is ​​established, and the stiffness matrix K = [Λ ij ] N×N , where Λ ij The 3×3 matrix represents the interaction between the i-th magnetic conductive ball and the j-th magnetic conductive ball, Λ ij =Λ ji T Different Λ ij The expression is as follows:

[0071]

[0072] Among them, Proj represents the interactive projection relationship, D ij is the direction matrix, indicating the direction of interaction. The specific expression is shown in Equations (3)-(4) and Figure 3 , θ and α are the angles between the body diagonal and the side length, and between the face diagonal and the side length of the primitive, respectively; the serial number of the magnetic ball is Figure 3 It has been noted in; represents the dot product of matrices, is the stiffness of a single cylindrical MRE, E, d MRE and h represent the magnetocompression modulus, diameter, and thickness of the columnar MRE, respectively.

[0073]

[0074] a, b, c, d, e, f, g in formula (4) refer to Figure 3 The position of the magnetic ball indicated in .

[0075] Fill the stiffness matrix K according to different positions to obtain the characteristic equation of the multi-degree-of-freedom system:

[0076] det(K-ω 2 M)=0 (5)

[0077] Solving the above equation (det function is used to find the determinant of a square matrix) yields 3N positive real roots, corresponding to the 3N natural angular frequencies of the system, i.e., ω1≤ω2≤...≤ω3N Since the system is three-dimensionally symmetrical, the three-order frequencies are equal, corresponding to the angular frequencies of the system in the X, Y, and Z directions. Therefore, the vibration absorber can be regarded as having the same N-order frequency in the three directions, specifically expressed as f X =f Y =f Z =[f1,...,f N ],in

[0078] The frequency conversion function of the three-dimensional cell-type vibration absorber is realized by relying on an external driving magnetic field. The present invention adopts an electromagnetic coil to provide a controllable magnetic field. Figure 4 The direction of the magnetic field in the vibration absorber and the corresponding equivalent magnetic circuit diagram are shown, where F a is the total magnetomotive force, N coil is the number of coil turns, I is the input current; R1, R2 and R MRE are the magnetic resistance of the magnetic block, magnetic ball and MRE respectively. Based on Ohm's law of magnetic circuit, the calculation relationship of the total magnetic circuit can be obtained as follows:

[0079] F a =N coil I=φR a

[0080] φ=BS (6)

[0081] R a =R1+R2+R MRE

[0082] Among them, F a is the magnetomotive force, φ is the total magnetic flux, B is the magnetic induction intensity, S is the area through which the magnetic field passes, R a is the total magnetic resistance.

[0083] The magnetic balls and blocks are made of No. 10 steel, and their relative magnetic permeability is usually above 5000, while the magnetic permeability of MRE is μ MRE ≈2. Therefore, the magnetic resistance of the first two is much smaller than that of MRE, so R a ≈R MRE , R MRE The specific expression is as follows:

[0084]

[0085] where μ0 = 4π × 10 -7 T·m / A is the vacuum magnetic permeability, and n·h is the effective magnetic path length of MRE.

[0086] MRE has a good magnetorheological effect when the magnetic field strength is 0.4 T. Taking B = 0.4 T, combining equations (6) and (7) yields equation (8), which can be used as a basis for subsequent coil design.

[0087]

[0088] The overall size of the three-dimensional cell vibration absorber is mainly composed of the side length of the cell (expressed by L) and the number of coil turns (expressed by N). coil (expressed), formula (9) is the specific expression of L. When designing, it is hoped that L and N coil The value of is as small as possible. Formula (10) is the relationship between the diameter of the MRE and the diameter of the magnetic ball. Considering the support requirements of the columnar MRE for the magnetic ball and the difficulty of demolding, γ is set to 0.25~0.6.

[0089]

[0090] 2πd MRE 2 =γπd0 2 (10)

[0091] Based on the dynamic model and equations (8) to (10), the change of the first-order frequency f1 of the vibration absorber under different combination parameters can be simulated. Figure 5 a shows the given L and N coil When n is 1, the frequency changes with n and γ. As γ and n increase, the natural frequency increases continuously. When n ≥ 5, the frequency changes slightly with further increase of n. Therefore, n ≤ 5 should be selected in the design. Figure 5 The figure b shows that when n and γ are given, the frequency changes with L and N. coil The results show that the natural frequency decreases with the increase of L; coil As I increases, it shows a trend of decreasing first and then increasing, especially when L is small. coil When I>7kA, the frequency increases sharply, so N is selected as much as possible during design. coil I≤7kA.

[0092] Example 3: Application of a three-dimensional unit cell vibration absorber

[0093] Figure 6 The parameter design process for a 3D lattice vibration absorber is presented. The robot's low-frequency modal coupling vibration frequency is typically between 10 and 30 Hz. Using this as the target frequency, the design parameters are shown in Table 1.

[0094] Table 1 Design parameters of three-dimensional cell vibration absorber

[0095]

[0096] Carbonyl iron powder, silicone rubber, and dimethyl silicone oil were mixed and cured in a mass ratio of 2:1:1 to obtain a reticulated MRE with the above parameters, which was used for the development of the vibration absorber prototype. Figure 7The developed vibration absorber prototype was displayed.

[0097] Robot dynamic compliance suppression experiment

[0098] Modal experiments were carried out with and without a vibration absorber prototype under different robot postures to verify the effect of the three-dimensional cell vibration absorber on suppressing the dynamic compliance of the robot in different modes. Figure 8 This article demonstrates the modal testing of the SIASUN GCR20-1100 collaborative robot. Hammering experiments were conducted on the robot in different postures using a DYTRAN 3263A2 triaxial accelerometer and a PCB 086C03 impulse sledge hammer. The collected signals were analyzed using the m+pVibRunner data acquisition system. Table 2 shows the experimental setup.

[0099] Table 2 Experimental settings

[0100]

[0101] Figure 9 The direct and cross frequency responses of the robot end before and after the vibration absorber is attached in posture 2 are given. The reference coordinate system is the tool coordinate system of the robot end (the tool coordinate system is used as a reference unless otherwise specified in the following text). xy The Y-direction excitation and X-direction response are similar. 12Hz and 25Hz were selected as suppression modes, respectively, and the control current of the vibration absorber was adjusted to suppress the different modes. When the current flowing through the vibration absorber was 0.3A, the maximum dynamic compliance of the 12Hz mode decreased from 136μm / N to 25μm / N, a decrease of 82%. Changing the control current of the vibration absorber to 1.9A reduced the maximum dynamic compliance of the 25Hz mode from 25.9μm / N to 2.6μm / N, a decrease of 86%. Figure 10 The experimental results for posture 4 are presented. The 3D lattice vibration absorber suppresses the robot's maximum dynamic compliance by 71% and 87% in the 12Hz and 29Hz modes, respectively. Results for the remaining postures are shown in Table 3. The prototype maintains three-dimensional stability at various rotation angles of the robot's end, with the maximum dynamic compliance suppression rate consistently exceeding 40%. These experimental results validate the suppression effectiveness of the 3D lattice vibration absorber prototype.

[0102] Table 3 Experimental results

[0103]

[0104] In summary, the present invention proposes a three-dimensional lattice vibration absorber structure. The vibration absorber is composed of a mesh MRE and magnetic spheres embedded therein in a lattice distribution. The overall structure is lattice-shaped and has three-dimensional symmetry. It can act in any direction in three-dimensional space and maintain its vibration suppression capability after rotation. The present invention performs dynamic modeling on the vibration absorber, analyzes the influence of various parameters on the natural frequency of the vibration absorber, and obtains a design basis for developing a prototype. Finally, a vibration absorber is attached to the end of the robot, and dynamic compliance suppression experiments are carried out. The experiments show that the prototype can suppress modes of different directions and frequencies, verifying the suppression effect and application value of the proposed vibration absorber.

[0105] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-dimensional lattice vibration absorber for suppressing time-varying chatter in robot milling, characterized in that: The device comprises a plurality of magnetic balls, a plurality of magnetorheological elastomers, a magnetic block, an electromagnetic coil, upper and lower walls, and four side walls; the upper and lower walls and the four side walls form a cubic structure, the electromagnetic coil is sleeved on the outer walls of the four side walls, the magnetic block is sleeved on the outer wall of the electromagnetic coil, and is connected to the upper and lower walls; the three-dimensional unit cell vibration absorber is a centrally symmetrical structure; Several magnetic balls are arranged in the cubic structure in the form of a body-centered cubic structure, and the inner wall of the cubic structure is connected to the magnetic balls. The magnetic ball located at the center of the body is connected to the magnetic balls located at the eight vertex corners through the magnetorheological elastomer.

2. The three-dimensional cellular vibration absorber according to claim 1, characterized in that: The magnetorheological elastomer is obtained by mixing carbonyl iron powder, silicone rubber and dimethyl silicone oil in a mass ratio of (1-3):(0.5-1.5):1 and curing.

3. The three-dimensional cellular vibration absorber according to claim 1, characterized in that: The magnetorheological elastomers used for connecting the magnetic conductive balls in the same layer are connected to each other through the magnetorheological elastomer to form a network structure.

4. The three-dimensional cellular vibration absorber according to claim 1, characterized in that: The magnetic conductive ball is connected to the magnetorheological elastomer by bonding, and the contact surface is in contact with the arc surface of the magnetic conductive ball; The magnetic conductive ball is connected to the inner wall of the cubic structure by welding.

5. The three-dimensional cellular vibration absorber according to claim 1, characterized in that: The magnetic balls and blocks are made of No. 10 steel. The side wall is made of non-magnetic aluminum alloy, and the upper and lower walls are made of magnetic material.

6. A design method for a three-dimensional cellular vibration absorber according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Determine the target vibration suppression frequency; S2. Preliminary determination of the side length L of the vibration absorber and the number of turns N of the electromagnetic coil coil and an applied current I; the side length L of the vibration absorber refers to the side length of the body-centered cubic structure composed of the magnetic sphere and the magnetorheological elastomer in the cubic structure; S3. Preliminarily give the initial values ​​of n and γ, and calculate the thickness h and diameter d of the magnetorheological elastomer according to the following formula MRE And the diameter d0 of the magnetic sphere: F a =N coil I=φR a φ=BS R a =R1+R2+R MRE 2πd MRE 2 =γπd0 2 Where n represents the number of body-centered cubic structure layers contained in each side of the vibration absorber, γ represents the ratio of the total contact area of ​​the eight magnetorheological elastomers and the magnetic sphere to the surface area of ​​the magnetic sphere; F a is the magnetomotive force, φ is the total magnetic flux, B is the magnetic induction intensity, S is the area through which the magnetic field passes, R a is the total magnetic resistance; R1, R2 and R MRE are the magnetic resistance of the magnetic block, magnetic ball and MRE, μ0=4π×10 - 7 T·m / A is the vacuum permeability; μ MRE is the magnetic permeability of the magnetorheological elastomer; S4. Calculate the natural frequency based on the dynamic model according to the design parameters preliminarily determined above; S5. Determine whether the natural frequency meets the requirements. If so, the parameters of steps S2 and S3 are the design parameters of the vibration absorber. If not, repeat steps S2-S5 until the optimized vibration absorber design parameters are obtained.

7. The design method according to claim 6, characterized in that: When determining the side length L, first select a value within 80 to 120 mm, and the number of turns N coil And the current I first flows through N coil The value is within the range of I≤7kA.

8. The design method according to claim 6, characterized in that: The value range of γ is 0.25~0.6; when determining the initial value of n, first determine it within the range of n≤5; And / or, the target vibration suppression frequency is 10 to 30 Hz.

9. The design method according to any one of claims 6 to 8, characterized in that: The method for constructing the kinetic model includes: (1) Establish the mass matrix of the n-layer three-dimensional unit cell vibration absorber: in, ρ and d0 represent the density and diameter of the magnetic sphere, respectively; (2) Establish the stiffness matrix K = [Λ ij ] N×N , where Λ ij is a 3×3 matrix, representing the interaction between the i-th magnetic conductive ball and the j-th magnetic conductive ball, Λ ij =Λ ji T ; (3) Fill the stiffness matrix K according to the different positions of the magnetic balls to obtain the characteristic equation of the multi-degree-of-freedom system: det(K-ω 2 M)=0 Solving the above equations, we get 3N positive real roots, corresponding to the 3N natural angular frequencies of the system, that is, ω1≤ω2≤...≤ω 3N ; (4) The three-dimensional unit cell vibration absorber is considered to have the same N-order frequency in three directions, which can be expressed as: in X =f Y =f Z =[f1,...,f N ] The natural frequency 10. The design method according to claim 9, characterized in that: Different Λ ij The expression is as follows: Among them, Proj represents the interactive projection relationship, D ij is the direction matrix, indicating the direction of interaction, θ and α are the angles between the body diagonal and the side length, and between the face diagonal and the side length of the primitive, respectively; represents the dot product of matrices, is the stiffness of a single columnar MRE; E represents the magnetocompression modulus of the columnar MRE; a, b, c, d, e, f, g represent the magnetic spheres at the eight corners of the body-centered cubic structure.

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