Shock absorber and design method thereof

Abstract

The invention discloses a shock absorber and a design method thereof, and belongs to the technical field of shock absorption devices. The shock absorber comprises an output rod, an outer cylinder, an inner cylinder and a shock absorption structure; one end of the output rod extends into the outer cylinder, and the extending end is connected with the inner cylinder; the vibration reduction structure comprises a plurality of damping bodies of a rotational symmetry structure. The inner wall of each damping body is connected with the outer wall of the inner cylinder, and the outer wall of each damping body is connected with the inner wall of the outer cylinder. According to the shock absorber, the structure is simple, a traditional integral type shock absorption structure is adjusted into the damping bodies of the rotary symmetrical structures, balance between the axial rigidity and the torsional rigidity can be achieved, therefore, the problem of vibration balance in the axial direction and the torsional direction is solved, the distribution and the size of the damping bodies are reasonably arranged, machining is convenient, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of vibration damping devices, and particularly relates to a shock absorber and a design method thereof. Background Art

[0002] Vibration phenomena widely occur in engineering practice. Generally, vibration can cause damage to the system, and vibrations of specific frequencies can also affect human health. Therefore, the need for vibration damping has existed for a long time. A shock absorber includes an elastic element and / or a damping element. The elastic element is used to provide an elastic force, and the damping element is used to absorb vibration energy. The shock absorber can effectively reduce the vibration amplitude, so it is widely used in various machines.

[0003] For shock-absorbing devices that consider both axial vibration and torsional vibration simultaneously, in the prior art, a cylindrical rubber shock-absorbing structure is adopted, which makes it difficult to achieve balance between axial and torsional vibrations, affecting the service life and shock-absorbing performance of the rubber shock absorber. Therefore, the difficulty in designing a rubber shock absorber lies in how to scientifically and reasonably design the distribution of the damping material in space under the limitations of cost and existing materials, so that while the suppression of axial vibration meets the requirements, the resonance frequencies in other directions are not too soft. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the present invention provides a shock absorber and a design method thereof, which have a simple structure, are convenient to process, have low costs, and can balance axial vibration and torsional vibration.

[0005] The present invention provides the following technical solutions:

[0006] In a first aspect, a shock absorber is provided, including an output rod, an outer cylinder, an inner cylinder, and a shock-absorbing structure; one end of the output rod extends into the outer cylinder, and the extending end is connected to the inner cylinder; the shock-absorbing structure includes a plurality of damping bodies with a rotationally symmetric structure; the inner wall of each damping body is connected to the outer wall of the inner cylinder, and the outer wall of each damping body is connected to the inner wall of the outer cylinder.

[0007] Optionally, there are three, four, or six damping bodies.

[0008] Optionally, the shock-absorbing structure has two layers and is respectively located at both axial ends of the inner cylinder.

[0009] Optionally, the inner cylinder is hollow, and the cross-section of the inner cylinder is annular or hollow hexagonal; the output rod is connected to the inner cylinder by a thread.

[0010] Optionally, both the outer cylinder and the inner cylinder are made of metal, and the material of the damping body is butyl rubber or nitrile rubber;

[0011] The outer cylinder includes an input end cover, an output end cover and a cylinder body; the input end cover and the output end cover are respectively detachably connected to both ends of the cylinder body; the output rod passes through the output end cover.

[0012] Optionally, buffer rubbers are arranged on the inner end faces of the output end cover and the input end cover, and the buffer rubbers are located between the inner cylinder and the output end cover or between the inner cylinder and the input end cover.

[0013] Optionally, the input end cover is connected with an input flange for connecting to a vibration source.

[0014] In a second aspect, a design method of a shock absorber is based on the shock absorber described in any one of the first aspect; the design method includes the following steps:

[0015] S1: According to the use environment of the shock absorber, obtain the basic ranges of the material properties, quantity and geometric parameters {a, b, h} of the damping body;

[0016] S2: Use the genetic algorithm to find the optimal geometric parameter set {a best , b best , h best} of the damping body within the basic ranges of the geometric parameters; in the process of finding the optimal geometric parameter set of the damping body, determine the fitness function f(h, a, b) according to the balance of the axial stiffness and torsional stiffness of the damping body;

[0017]

[0018] wherein, a and b are respectively the length and width of the damping body in the cross-section of the inner cylinder, and h is the thickness of the damping body in the axial section of the inner cylinder; f r is the natural frequency of torsional vibration, and f a is the natural frequency of axial vibration.

[0019] Optionally, step S2 specifically includes:

[0020] S2.1: Encode the geometric parameters {a, b, h} into a binary string α i = C[{a i , b i , h i}] according to the defined coding rule C;

[0021] S2.2: Randomly generate an initial population P0 = {α1, α2, α3, …, α n} within the basic ranges of the geometric parameters {a, b, h}, the initial population includes multiple individuals, and each individual represents a geometric dimension combination;

[0022] S2.3: Calculate the fitness value of each individual in the current population according to the constructed fitness function;

[0023] S2.4: According to the set crossover probability, reproduction rules, and mutation rules, in each iteration, after performing fitness selection, crossover, and mutation operations, generate a new population and calculate the fitness value of each individual in the new population;

[0024] S2.5: Evaluate and select the new population according to the fitness value, eliminate individuals with low fitness, and retain individuals with high fitness. Until the iteration termination condition is met, obtain the current optimal solution α best , and according to the set decoding rule C -1 , decode the optimal solution α best , and obtain the optimal parameter combination {a best , b best , h best};

[0025] Among them, when calculating the fitness value of each individual in step S2.3 and step S2.4, decode the binary string α i into the parameter combination {ai, bi, hi}, and establish a finite element model according to the parameter combination {ai, bi, hi} to calculate the natural frequency f of torsional vibration r and the natural frequency f of axial vibration a .

[0026] Optionally, when there are three damping bodies, apply forces F with equal values and the same direction to each damping body respectively. At this time, the damping bodies undergo axial vibration, and the natural frequency f of the axial vibration a is:

[0027]

[0028] When there are three damping bodies, apply forces F with equal values to each damping body respectively, and the force direction of the current damping body is different from that of the other two damping bodies. At this time, the current damping body undergoes torsional vibration, and the natural frequency f of the torsional vibration r is:

[0029]

[0030] Among them, k α is the axial vibration stiffness, m is the mass of the vibration damping device to be reduced; l is the distance between the centroid of the inner cylinder and the centroid of the vibration damping device to be reduced, Δh is the displacement of the damping body in the axial direction of the inner cylinder when the damping body undergoes axial vibration, Δx is the lateral displacement between the current damping body and the adjacent damping body when the damping body undergoes torsional vibration, and Δα is the torsional angle of the damping body when the damping body undergoes torsional vibration.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The shock absorber provided in the present application has a simple structure. The traditional integral shock absorber structure is adjusted into a plurality of damping bodies with rotationally symmetrical structures, which can achieve a balance between axial stiffness and torsional stiffness, thereby solving the vibration balance problem in the axial and torsional directions. The shock absorber of the present application rationally arranges the distribution and size of the damping bodies, is easy to process, and has low cost.

[0033] (2) The shock absorber design method provided in this application avoids a large number of trial and error procedures, utilizes the active search capability of the genetic algorithm, and uses finite element analysis software to design and iteratively optimize the shock absorber. The calculation is simple, the solution is comprehensive and reliable, and the dimensional parameters of the damping body can be quickly and reliably obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the overall structure of the shock absorber of the present invention;

[0035] Figure 2 is a schematic diagram of the internal structure of the shock absorber of the present invention;

[0036] Figure 3 is a top view of the vibration reduction structure of the present invention when the vibration reduction structure includes three damping bodies;

[0037] Figure 4 is a top view of the vibration reduction structure of the present invention when the vibration reduction structure includes four damping bodies;

[0038] Figure 5 is a top view of the vibration reduction structure of the present invention when the vibration reduction structure includes six damping bodies;

[0039] Figure 6 It is a parameter marking schematic diagram of the damping body of the present invention;

[0040] Figure 7 is a node marking schematic diagram of a damping body according to Embodiment 3 of the present invention;

[0041] Figure 8 It is a schematic diagram of the deformation of the damping body when an axial load is applied in the present invention;

[0042] Figure 9 It is a schematic diagram of deformation of the damping body after torsion when loads in different directions are applied to relevant positions of the damping body of the present invention.

[0043] Markings in the figure are: 1 is the output rod, 2 is the outer cylinder, 21 is the input end cover, 22 is the output end cover, 23 is the cylinder body, 24 is the input flange, 25 is the buffer rubber, 3 is the inner cylinder, 4 is the vibration reduction structure, and 41 is the damping body. DETAILED DESCRIPTION

[0044] The present invention will now be described in further detail with reference to the accompanying drawings.

[0045] It should be noted that the terms such as "upper", "lower", "left", "right", "front", and "rear" cited in the invention are only for the sake of clarity in narration and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention. The term "comprising" in the specification and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusion.

[0046] Embodiment 1

[0047] As Figure 1 - Figure 2 shown, a shock absorber is provided, which includes an output rod 1, an outer cylinder 2, an inner cylinder 3, and a shock-absorbing structure 4; the output rod 1 is used to connect the device to be shock-absorbed, one end of the output rod 1 is inserted into the outer cylinder 2, and the inserted end can swing at a certain angle and can also have a certain amount of telescoping relative to the outer cylinder 2. The existence of the swing angle is mainly used to absorb torsional vibration. Therefore, the swing angle is not likely to be too large and can be determined according to expert experience; the end of the output rod 1 extending into the outer cylinder 2 is connected to the inner cylinder 3; the shock-absorbing structure 4 includes a number of damping bodies 41 with a rotationally symmetric structure; the inner wall of each damping body 41 is connected to the outer wall of the inner cylinder 3, and the outer wall of each damping body 41 is connected to the inner wall of the outer cylinder 2. The damping bodies 41 are fixed to the inner cylinder 3 and the outer cylinder 2 by adhesive.

[0048] As Figure 3 - Figure 5 shown, in this embodiment, there are three, four, or six damping bodies 41. That is, when there are three damping bodies 41, the included angle between adjacent damping bodies 41 is 120°; when there are four damping bodies 41, the included angle between adjacent damping bodies 41 is 90°; when there are six damping bodies 41, the included angle between adjacent damping bodies 41 is 60°.

[0049] In this embodiment, the shock-absorbing structure 4 has two layers and is respectively located at both axial ends of the inner cylinder 3. In some other embodiments, the shock-absorbing structure 4 can also have only one layer, which can be selected according to the usage requirements.

[0050] In this embodiment, the inner cylinder 3 is hollow, and the cross-section of the inner cylinder 3 is a hollow hexagon or a ring; the output rod 1 is connected to the inner cylinder 3 by threads; of course, in some other embodiments, the inner cylinder 3 can also be solid.

[0051] In this embodiment, both the outer cylinder 2 and the inner cylinder 3 are made of metal, and the damping body 41 is made of butyl rubber or nitrile rubber; the outer cylinder 2 includes an input end cover 21, an output end cover 22 and a cylinder body 23; the input end cover 21 and the output end cover 22 are respectively detachably connected to both ends of the cylinder body 23; the output rod 1 passes through the output end cover 22. In order to further improve the vibration damping effect, buffer rubbers 25 are provided on the inner end faces of the output end cover 22 and the input end cover 21. The buffer rubber 25 located between the inner cylinder 3 and the output end cover 22 can be in the shape of a disc, and the buffer rubber 25 located between the inner cylinder 3 and the input end cover 21 is in a ring structure. In order to facilitate connection with the vibration source, the input end cover 21 is connected with an input flange 24.

[0052] The working process of this application is as follows: Connect the vibration source to the input flange 24, the flange connects the input end cover 21, the input end cover 21 and the output end cover 22 are connected to the cylinder body 23 to form the outer cylinder 2, the damping body 41 is adhered between the inner cylinder 3 and the outer cylinder 2, the output rod 1 is connected to the device to be vibration-damped. When the vibration source generates axial vibration and torsional vibration, the input end cover 21 undergoes torsion or axial movement, thereby driving the damping body 41 to undergo torsion and axial displacement. Under the damping action of the damping body 41, the vibration decays, so that the device to be vibration-damped undergoes vibration decay.

[0053] Based on the axial stiffness and torsional stiffness of the balanced vibration damping structure 4, to improve stability, optimize the vibration damping effect, and extend the service life. As a preference, through simulation, it is learned that the inner cylinder 3 is hollow and there are three damping bodies 41. At this time, the natural frequency f of torsional vibration r After testing, it can reach 5.8 Hz, and the natural frequency f of axial vibration a Can reach 16.6 Hz, and the balance effect of axial stiffness and torsional stiffness is the best; when there are four damping bodies 41, at this time, the natural frequency f of torsional vibration r After testing, it can reach 6.7 Hz, and the natural frequency f of axial vibration a Can reach 19.3 Hz, and the balance effect is the second best. When there are six damping bodies 41, at this time, the natural frequency f of torsional vibration r After testing, it can reach 8 Hz, and the natural frequency f of axial vibration a Can reach 23.4 Hz, and the balance effect is relatively the worst. The shock absorber of this application can solve the vibration balance problem in the axial and torsional directions, reasonably arrange the distribution and size of the damping body 41, is convenient for processing, and has low cost.

[0054] Embodiment 2

[0055] As Figure 6 shown, a design method of a shock absorber is provided. Based on the shock absorber of Embodiment 1, it includes the following steps:

[0056] S1: According to the usage environment of the shock absorber, obtain the basic ranges of the material properties, quantity, and geometric parameters {a, b, h} of the damping body 41.

[0057] The material properties of the damping body 41 include the type of material and the density of the material; the quantity of the damping body 41 is usually three, four, or six.

[0058] S2: Use the genetic algorithm to find the optimal set of geometric parameters {a best , b best , h best} of the damping body 41 within the basic ranges of the geometric parameters; during the process of finding the optimal set of geometric parameters of the damping body 41, determine the fitness function f(h, a, b) according to the balance of the axial stiffness and torsional stiffness of the damping body 41;

[0059]

[0060] wherein, a and b are respectively the length and width of the damping body 41 in the cross-section of the inner cylinder 3, and h is the thickness of the damping body 41 in the axial section of the inner cylinder 3; f r is the natural frequency of torsional vibration, and f a is the natural frequency of axial vibration.

[0061] Step S2 specifically includes:

[0062] S2.1: Encode the geometric parameters {a, b, h} into a binary string α i = C[{a i , b i , h i}] according to the defined encoding rule C.

[0063] The encoding rule can be determined according to the prior art.

[0064] S2.2: Randomly generate an initial population P0 = {α1, α2, α3, …, α n} within the basic ranges of the geometric parameters {a, b, h}, where the initial population includes multiple individuals, and each individual represents a combination of geometric dimensions.

[0065] S2.3: Calculate the fitness value of each individual in the current population according to the constructed fitness function;

[0066] S2.4: According to the set crossover probability, reproduction rule, and mutation rule, in each iteration, after performing fitness selection, crossover, and mutation operations, generate a new population and calculate the fitness value of each individual in the new population;

[0067] The crossover probability, reproduction rule, and mutation rule can be determined according to the prior art. Optionally, the reproduction rule can be to randomly select two surviving individuals from the previous generation for crossover and then perform mutation. For binary encoding, the crossover rule generally uses single-point crossover, and the mutation rule generally selects bit-flip mutation. The selection rule can be the roulette wheel selection method or the ranking selection method. The termination condition can generally be achieved by explicitly iterating a certain number of generations. The roulette wheel selection method designs the survival probability of an individual based on the fitness function, so that individuals with a higher fitness have a greater probability of surviving to the next generation, while individuals with a lower fitness function are more likely to be eliminated. At the same time, since it ensures that individuals with a lower fitness function also have a certain probability of being preserved, this method can often jump out of the local optimal solution, but its convergence speed is relatively low. The ranking selection method sorts according to the size of the fitness function and selects the largest several individuals to survive to the next iteration. This method has a fast convergence speed, but whether it can jump out of the local optimal solution depends only on a relatively good initial population, and the selection rule can be chosen according to actual needs.

[0068] S2.5: Evaluate and select the new population according to the fitness value, eliminate individuals with low fitness, and retain individuals with high fitness. After meeting the iteration termination condition, obtain the current optimal solution α best , and according to the set decoding rule C -1 , decode the optimal solution α best , to obtain the optimal parameter combination {a best , b best , h best};

[0069] Among them, when calculating the fitness value of each individual in steps S2.3 and S2.4, decode the binary string α i into the parameter combination {ai, bi, hi}, and establish a finite element model according to the parameter combination {ai, bi, hi} to calculate the natural frequency f r of torsional vibration and the natural frequency f a of axial vibration. The method of establishing the finite element model refers to the prior art. Specifically, it can directly use existing software, such as ANSYS for modeling.

[0070] When there are three damping bodies 41, apply forces F with equal values and the same direction to each damping body 41 respectively. At this time, the damping body 41 undergoes axial vibration, and the natural frequency f a of the axial vibration is:

[0071]

[0072] When there are three damping bodies 41, equal forces F are applied to each damping body 41 respectively, and the direction of the force on the current damping body 41 is different from that of the other two damping bodies 41. At this time, the current damping body 41 undergoes torsional vibration, and the natural frequency f of the torsional vibration r is:

[0073]

[0074] where k α is the stiffness of the axial vibration, m is the mass of the device to be vibration-damped; l is the distance between the centroid of the inner cylinder 3 and the centroid of the device to be vibration-damped, Δh is the displacement of the damping body 41 in the axial direction of the inner cylinder 3 when the damping body 41 undergoes axial vibration, Δx is the lateral displacement between the current damping body 41 and the adjacent damping body 41 when the damping body 41 undergoes torsional vibration, and Δα is the torsional angle of the damping body 41 when the damping body 41 undergoes torsional vibration. Among them, Δh, Δx, and Δα are affected by the material properties of the rubber damping body 41 and are obtained through existing measurement techniques.

[0075] Specifically, when establishing a finite element model, for a linearly elastic material, the stiffness of a specific vibration mode can be obtained by solving the static deformation of the system in the corresponding direction caused by a unit external load. Therefore, by adding a unit axial force at the symmetric position of the vibration-damping structure 4 to obtain the axial displacement during the axial vibration of the damping body 41, the natural frequency of the axial vibration can be calculated. For the calculation of the natural frequency of torsional vibration, since a torque cannot be applied to the damping body 41 element. Therefore, by adding unit concentrated loads in different directions at relevant positions inside the vibration-damping structure 4 to achieve torsion, and then calculating the natural frequency of torsional vibration by solving the rotation under the external load.

[0076] Example 3

[0077] A specific example of a design method for a shock absorber is provided. The vibration-damping structure 4 is double-layered, and each vibration-damping structure 4 includes three damping bodies 41. The inner cylinder 3 is hollow, and the cross-sectional shape is a hollow hexagonal structure.

[0078] The fitness function of this example is:

[0079] where the geometric parameter range of each damping body is shown in Table 1 below:

[0080] Table 1 Geometric parameter range of each damping body

[0081] <![CDATA[h0]]> <![CDATA[h1]]> <![CDATA[b0]]> <![CDATA[b1]]> <![CDATA[a0]]> <![CDATA[a1]]> 8mm 15mm 15mm 20mm 18mm 22mm

[0082] Within the range of the geometric parameters of each damping body 41, the genetic algorithm is used to find the optimal set of geometric parameters of the damping body 41.

[0083] Specifically, the coding rule is defined as follows:

[0084]

[0085] Among them, the function Round(x) represents the integer closest to x, and the function Bin(x) represents the integer x within 0 to 15 in 4-bit binary coding. For example:

[0086] C(10.8, 18.3, 18.1) = {0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1}

[0087] C(13.6, 15.6, 20.9) = {1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1}

[0088] The number of surviving individuals in each iteration N = 3. Each time reproduction occurs, 2 individuals are randomly selected from the individuals that survived in the previous generation for crossover and mutation, and one of them is randomly selected. The above process is repeated 6 times.

[0089] Crossover rule: In this example, midpoint crossover is selected.

[0090] Mutation rule: In this example, flip mutation is selected, and the mutation probability is fixed at 0.05.

[0091] Selection rule: In this example, the selection method is sorting selection.

[0092] Given the following initial population:

[0093] {0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1}, {1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1}, {1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1}

[0094] Termination condition: In this example, the calculation is terminated randomly after 20 generations of iteration.

[0095] Among them, when calculating the fitness value in each iteration, the axial vibration mode shape and torsional vibration mode shape obtained by using the finite element analysis software are used. Through the mode shape, it can be found that the contributions of the damping bodies 41 at different positions to the stiffness of the axial vibration and torsional vibration are different. For torsional vibration, the deformation of the damping body 41 connected to the internal structure is smaller than that of the material connected to the outer shell. On the contrary, for axial vibration, the deformation of the damping body 41 connected to the inner cylinder 3 is the same as that of the material connected to the outer shell. Based on this, removing the central part of the inner cylinder 3 can effectively achieve the balance between the torsional vibration natural frequency and the axial vibration natural frequency.

[0096] Use the finite element software to construct the model of the vibration damping structure 4, as Figure 7 - Figure 9As shown, label the numbers of the nodes of the vibration damping structure 4; Considering geometric symmetry, apply an axial force of 1 unit vertically upward to nodes 2, 14, and 26 respectively. By calculating the axial displacement (denoted as Δh) at node 2, the natural frequency of axial vibration can be calculated. Next, apply an axial force of 2 units downward at node 2, and apply an axial force of 1 unit upward at nodes 14 and 26. This combination produces a torsional effect, and the natural frequency of torsional vibration is calculated by measuring the deflection angle (denoted as Δα) of the internal structure.

[0097] The stiffness of axial vibration is: k α = 3F / Δh, and the natural frequency of axial vibration is:

[0098]

[0099] Where, m represents the mass of the device to be vibration-damped, and Δh represents the displacement of the rubber body 41 in the axial direction of the inner cylinder 3 when the damping body 41 undergoes axial vibration, where. F = 1N. Similarly, the natural frequency of torsional vibration can be calculated as follows:

[0100]

[0101] Where. Δx = |x(2) - x(14)|. x(2) is Figure 7 the abscissa value of the 2nd node in Figure 7 and x(14) is

[0102] When the iteration termination condition is reached, the optimal size combination obtained by calculation is: h = 11.73mm, b = 16mm, a = 22mm.

[0103] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts between the various embodiments, reference can be made to each other.

[0104] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A shock absorber, characterized in that: The invention comprises an output rod (1), an outer cylinder (2), an inner cylinder (3) and a vibration-damping structure (4); one end of the output rod (1) extends into the outer cylinder (2), and the extending end is connected to the inner cylinder (3); the vibration-damping structure (4) comprises a plurality of damping bodies (41) of rotationally symmetrical structure; the inner wall of each damping body (41) is connected to the outer wall of the inner cylinder (3), and the outer wall of each damping body (41) is connected to the inner wall of the outer cylinder (2).

2. The shock absorber according to claim 1, characterized in that: The number of the damping bodies (41) is three, four or six.

3. The shock absorber according to claim 1, characterized in that: The vibration reduction structure (4) has two layers and is respectively located at two axial ends of the inner cylinder (3).

4. The shock absorber according to claim 1, characterized in that: The inner cylinder (3) is hollow, and the cross section of the inner cylinder (3) is annular or hollow hexagonal; the output rod (1) is connected to the inner cylinder (3) via threads.

5. The vibration absorber according to claim 1, characterized in that: The outer cylinder (2) and the inner cylinder (3) are both made of metal, and the damping body (41) is made of butyl rubber or nitrile rubber; The outer cylinder (2) comprises an input end cover (21), an output end cover (22) and a cylinder body (23); the input end cover (21) and the output end cover (22) are respectively detachably connected to the two ends of the cylinder body (23); and the output rod (1) passes through the output end cover (22).

6. The shock absorber according to claim 5, characterized in that The inner end surfaces of the output end cover (22) and the input end cover (21) are both provided with a buffer rubber (25), and the buffer rubber (25) is located between the inner cylinder (3) and the output end cover (22) or between the inner cylinder (3) and the input end cover (21).

7. The vibration absorber according to claim 5, characterized in that: The input end cover (21) is connected to an input flange (24) for connecting to a vibration source.

8. A method for designing a shock absorber, characterized in that: Based on the shock absorber described in any one of claims 1 to 7; the design method comprises the following steps: S1: obtaining the basic range of material properties, quantity and geometric parameters {a, b, h} of the damping body (41) according to the use environment of the shock absorber; S2: Using genetic algorithm, find the optimal set of geometric parameters {a, b, h} of the damping body (41) in the basic range of geometric parameters {a, b, h} best ,b best ,h best }; In the process of finding the optimal set of geometric parameters of the damping body (41), the fitness function f(h, a, b) is determined according to the balance between the axial stiffness and the torsional stiffness of the damping body (41); Wherein, a and b are respectively the length and width of the damping body (41) in the cross section of the inner cylinder (3), and h is the thickness of the damping body (41) in the axial section of the inner cylinder (3); f r is the natural frequency of torsional vibration, f a is the natural frequency of axial vibration.

9. The design method of a vibration absorber according to claim 8, characterized in that: Step S2 specifically includes: S2.1: Encode the geometric parameters {a, b, h} into a binary string α according to the defined encoding rule C i =C[{a i ,b i ,h i }]; S2.2: In the basic range of geometric parameters {a, b, h}, randomly generate an initial population P0 = {α1, α2, α3, …, α n }, the initial population includes multiple individuals, and each individual represents a combination of geometric dimensions; S2.3: Calculate the fitness value of each individual in the current population according to the constructed fitness function; S2.4: According to the set crossover probability, reproduction rules and mutation rules, in each iteration, after performing fitness selection, crossover and mutation operations, a new population is generated and the fitness value of each individual in the new population is calculated; S2.5: Evaluate and select the new population according to the fitness value, eliminate individuals with low fitness, and retain individuals with high fitness until the iteration termination condition is met to obtain the current optimal solution α best , and according to the set decoding rule C -1 , decoding optimal solution α best , get the optimal parameter combination {a best ,b best ,h best }; In step S2.3 and step S2.4, when calculating the fitness value of each individual, the binary string α i Decode it into a parameter combination {ai,bi,hi}, and establish a finite element model based on the parameter combination {ai,bi,hi} to calculate the natural frequency f of torsional vibration r and the natural frequency of axial vibration f a .

10. The design method of a vibration absorber according to claim 9, characterized in that: When there are three damping bodies (41), a force F having an equal value and the same direction is applied to each damping body (41), and the damping body (41) vibrates axially at this time, and the natural frequency of the axial vibration is f a for: When there are three damping bodies (41), a force F of equal value is applied to each damping body (41), and the force direction of the current damping body (41) is different from the force directions of the other two damping bodies (41). At this time, the current damping body (41) undergoes torsional vibration, and the natural frequency of the torsional vibration is f r for: Among them, k α is the stiffness of axial vibration, m is the mass of the device to be damped; l is the distance between the center of mass of the inner cylinder (3) and the center of mass of the device to be damped, Δh is the displacement of the damping body (41) in the axial direction of the inner cylinder (3) when the damping body (41) undergoes axial vibration, Δx is the lateral displacement between the current damping body (41) and the adjacent damping body (41) when the damping body (41) undergoes torsional vibration, and Δα is the torsional angle of the damping body (41) when the damping body (41) undergoes torsional vibration.

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