CN111550514A - Multi-frequency dynamic vibration absorption method and multi-frequency dynamic vibration absorber - Google Patents

Multi-frequency dynamic vibration absorption method and multi-frequency dynamic vibration absorber Download PDF

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CN111550514A
CN111550514A CN202010264598.0A CN202010264598A CN111550514A CN 111550514 A CN111550514 A CN 111550514A CN 202010264598 A CN202010264598 A CN 202010264598A CN 111550514 A CN111550514 A CN 111550514A
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vibration
mass
unit
frequency
modal
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CN111550514B (en
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涂奉臣
贺才春
胡小刚
肖光辉
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Zhuzhou Times New Material Technology Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00—Vibration-dampers; Shock-absorbers
    • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
    • F16F7/1022—Vibration-dampers; Shock-absorbers using inertia effect the linear oscillation movement being converted into a rotational movement of the inertia member, e.g. using a pivoted mass
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00—Vibration-dampers; Shock-absorbers
    • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
    • F16F7/104—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00—Vibration-dampers; Shock-absorbers
    • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
    • F16F7/104—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted
    • F16F7/108—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted on plastics springs

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  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Vibration Prevention Devices (AREA)

Abstract

A multi-frequency dynamic vibration absorption method and a multi-frequency dynamic vibration absorber increase the vibration mode of a dynamic vibration absorption unit by connecting a connecting part and a mass block in a spatial angle manner, thereby reducing the distribution number of the vibration absorption units on a fixed unit, simplifying the structure by rigid connection among the connecting part, the mass block and the fixed unit, increasing the stability of the whole structure and reducing the influence of frequency matching errors caused by gaps among components. The multi-frequency dynamic vibration absorption method and the multi-frequency dynamic vibration absorber have simple structures and good stability, and can effectively eliminate the influence of a plurality of discrete vibration inherent frequencies of a controlled object.

Description

Multi-frequency dynamic vibration absorption method and multi-frequency dynamic vibration absorber
Technical Field
The invention relates to the field of engineering vibration control, in particular to a multi-frequency dynamic vibration absorption method and a multi-frequency dynamic vibration absorber.
Background
In the field of engineering vibration control, vibration reduction using a dynamic vibration absorber is one of the common methods. The dynamic vibration absorber consists of auxiliary mass, spring and damper, and its vibration natural frequency is regulated to near the main structure resonant frequency to change the main structure resonant characteristic and thus to reduce vibration of the main structure. The dynamic vibration absorber has the advantages of simple structure, convenient construction and maintenance, good vibration reduction effect, lower cost and the like, is widely used in the fields of buildings, bridges, ships, automobiles, machining and the like, and has obvious effect of inhibiting stable single-frequency vibration (or line spectrum vibration).
The basic structure of the dynamic vibration absorber includes a mass part and a spring part, and a damping part may be added if necessary. The natural frequency of the dynamic vibration absorber itself is determined by its massmAnd stiffnesskDetermining that the natural frequency of the dynamic vibration absorber itself is
Figure DEST_PATH_IMAGE002
. When the natural frequency of the dynamic-vibration absorber is the same as or close to the resonance frequency of the controlled object (main structure), the dynamic-vibration absorber resonates. During the resonance process of the dynamic vibration absorber, a force opposite to the vibration direction of the controlled object is generated and acts on the controlled object, so that the vibration response of the controlled object is inhibited. Macroscopically, the vibration energy of the controlled object is absorbed onto the dynamic vibration absorber equivalently, and the vibration response of the controlled object is reduced and is prevented from being damaged by vibration.
Most of the dynamic vibration absorbers common in engineering can only absorb single-frequency vibration. However, in many cases, the vibration source is very complex, the controlled object is often excited by a plurality of single-frequency vibrations, and each frequency spans a wide frequency band, and the vibration response for each frequency needs to be suppressed. In this case, if one model of the dynamic vibration absorber is designed for each excitation frequency, the workload is large, and the number of the vibration absorbers is excessive, which leads to an increase in installation space and an excessive increase in weight, which is generally unacceptable in practical engineering. In order to solve the problem of suppression of multi-frequency vibrations, multi-frequency (or broadband) dynamic vibration absorbers have been developed.
In the prior art, (1) vibration active/semi-active control is adopted, that is, the frequency change of vibration excitation is obtained through a sensor, and after the frequency change is processed by a controller, parameters (such as rigidity, mass and the like) of the dynamic vibration absorber are changed through an actuator, so that the natural frequency of the dynamic vibration absorber is changed along with the change of the external excitation frequency. Although the method has obvious effect, the reliability of the system is reduced and the cost is greatly increased due to the introduction of an electronic control system and the need of inputting energy from the outside, so the method is generally used under the condition of extremely small number of negligible cost and is rarely adopted in the field of general civil engineering.
(2) Still adopt vibration passive control, compound the dynamic vibration absorber of multiple frequency together. Like the patent, "a wide band vibration absorption sound insulation support with adjustable" (CN 201910117580.5) through combining cantilever beam dynamic vibration absorber and isolator, realize a wide range of application and adjustable operating frequency's wide band vibration absorption sound insulation support with adjustable. Furthermore, as in the patent "a combined broadband dynamic vibration absorber" (CN 201810955036.3), a plurality of damping bases with uniform sizes are adopted, and the dynamic vibration absorbing units are combined by the frame body, so that a plurality of discrete frequencies can be targeted and vibration absorbed; the invention is composed of a damping base body and a mass block, the working frequency variation range is wide, and the sensitivity of the working frequency variation is high when the relative position of the mass block is adjusted. The approach adopting the passive control is simple in principle and convenient to implement. As another example, the patent "a frequency-tunable broadband dynamic vibration absorber and vibration absorbing method thereof" (CN 201610599120.7) includes a base, a screw rod vertically installed on the base, a fixed vibration absorbing unit, at least one set of moving vibration absorbing units, a nut, and a sliding metal plate.
In the above documents, the natural vibration frequency of the mobile vibration absorbing unit is changed by the relative position of the mobile mass block, so that the vibration absorption of a plurality of discrete natural vibration frequencies is realized, and once the position of the mobile mass block is determined, the vibration mode of a single vibration unit has only one or at most two vibration modes. When the controlled object has more discrete natural vibration frequencies, the moving vibration units are mounted more frequently to absorb the discrete natural vibration frequencies, which results in excessive weight and volume of the entire vibration absorber. And the related structural components of the moving mass block are movably connected, the number of the components is particularly small, the number of the components is more and complicated, and the movable clearance between the components influences the matching of the vibration absorption frequency and the natural vibration frequency of the controlled object and finally influences the vibration absorption effect.
Therefore, the multi-frequency dynamic vibration absorption method and the multi-frequency dynamic vibration absorber with simple structural steps and multi-order modal vibration have great significance in the technical field.
Disclosure of Invention
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a multi-frequency dynamic vibration absorption method is adopted, and comprises the following steps of providing a vibration absorption material with rigidity KaAnd at least one of the fixing units has a rigidity KbIn the vibration absorbing unit of, wherein Ka>Kb；
Rigidly connecting the vibration absorption unit to the fixing unit;
fixedly connecting the fixed unit with the controlled object;
the vibration absorption unit has fixed multi-order modal vibration frequency, the multi-order modal vibration frequency of the vibration absorption unit is matched with a plurality of natural vibration frequencies of the controlled object, and when the first-order modal vibration frequency of the vibration absorption unit is equal to the natural vibration frequency of the controlled object, the natural vibration of the controlled object is absorbed by the vibration absorption unit.
Furthermore, the vibration absorption unit consists of a connecting part and a mass block; one end of the connecting part is rigidly connected with the fixing unit, and the other end of the connecting part is rigidly connected with the mass block and is provided with a rigid connecting point A and a gravity center O2So that the mass block generates up-and-down modal vibration x to the connecting part by the rigid connecting point A1；
The mass block has a center of gravity O2Center of gravity O1Arranged at a rigid connection point A and a center of gravity O2Wired external unit AO2O1Form a certain angle α between them, so that the mass can generate torsional mode vibration omega around the connection part1；
The mass generates a center of mass modal vibration omega about the center of gravity O22(ii) a The up-down modal vibration x1Torsional mode of vibrationVibration omega1And center of mass modal vibration omega2Forming third-order mode vibration.
Further, n vibration absorbing units are rigidly connected to the fixing unit, and each vibration absorbing unit is rigidly connected with a point AnAnd center of gravity O2nAnd center of gravity O1nForm an angle αnAngle α of each of the abovenAre set to be unequal to each other so that the torsional mode vibration omega of each vibration absorbing unit1nThe natural frequencies are different;
setting the size, the mass and the rigidity of the connecting part of each vibration absorbing unit to be unequal to each other, so that the upper and lower modal vibration x of each vibration absorbing unit1nAre not equal;
setting the size, the mass and the rigidity of each mass block to be unequal to each other, so that the mass center modal vibration omega of each vibration absorption unit2nSo that the combination of the vibration absorbing units has a fixed multi-order modal vibration frequency.
Further, a plurality of vibration frequencies fn which are most significant in the vibration response of the controlled object are extracted, and the angle α is adjustednOr adjusting the size, rigidity and mass of each connecting part or adjusting the size, rigidity and mass of each mass block to enable the mass center modal vibration omega of at least one vibration absorption unit to vibrate2nOr up and down modal vibration x1nOr torsional mode vibration omega1nIs equal to fn, whereby the multi-order modal vibration frequencies of the vibration absorbing unit are matched with the natural frequencies of the controlled object matching fn.
The invention also provides a multi-frequency dynamic vibration absorber, which comprises at least one vibration absorbing unit and a fixing unit, wherein one end of the fixing unit is fixedly connected with a controlled object, the vibration absorbing unit comprises a connecting part and a mass block, one end of the connecting part is rigidly connected with the fixing unit, the other end of the connecting part is rigidly connected with one end of the mass block and is provided with a rigid connection point A, and the connecting part and the mass block form a certain space angle by taking the rigid connection point A as a vertex; the rigidity of the fixing unit is greater than that of the vibration absorbing unit.
Furthermore, the connecting part is a cylindrical or cuboid rigid cantilever beam, one end of the cantilever beam is connected with one end of the mass block through threads or riveting, and the rigidity of the fixing unit is greater than that of the cantilever beam.
Furthermore, the mass block is dumbbell-shaped with larger sizes at two ends and smaller size in the middle.
Further, the fixing unit comprises a connecting thread, a fastening nut, a support column, a lower clamping plate and an upper clamping plate; one end of the supporting column is fixedly connected with the controlled object through a connecting thread and a fastening nut, the other end of the supporting column is fixedly connected with the lower clamping plate and the upper clamping plate, one end of the connecting portion is clamped and fixed by the lower clamping plate and the upper clamping plate, and the rigidity of the lower clamping plate and the rigidity of the upper clamping plate are larger than that of the connecting portion.
Furthermore, the outer surface of the connecting part is covered with a constrained damping layer which comprises a damping layer I and a damping layer II, the damping layer I is made of a material easy to shear and deform and covers the outer surface of the connecting part, and the damping layer II is a thin plate made of a rigid material and covers the outer surface of the damping layer I.
Furthermore, the plurality of vibration absorbing units are fixedly connected with the fixing unit in an evenly distributed manner through respective connecting parts, the rigidity, the mass and the size of the connecting parts of the vibration absorbing units are different, and the rigidity, the mass and the size of the mass blocks of the vibration absorbing units are different.
The invention has the following advantages:
1. the vibration absorption units in the invention are connected through the space angles of the mass blocks and the connecting parts, so that a single vibration absorption unit has three modal vibration frequencies, and when the natural vibration frequency of a controlled object is higher, the distribution number of the vibration absorption units is reduced compared with the prior art, and the weight and the volume of the whole dynamic vibration absorber are reduced.
2. The relative position of the mass block of the vibration absorption unit is fixed, the structure of the vibration absorption unit is simplified on the basis of increasing the vibration mode, and the connecting part, the mass block and the fixing unit are all in rigid connection, so that the structure of the vibration absorption unit is simple and stable, and the influence on the vibration absorption frequency is small.
Drawings
FIG. 1: the vibration mode schematic diagram of the dynamic vibration absorption unit;
FIG. 2: the structure of the multi-frequency dynamic vibration absorber is shown as I;
FIG. 3: the structure of the multi-frequency dynamic vibration absorber is shown as II;
FIG. 4: a damping layer distribution schematic diagram;
FIG. 5: and the dynamic vibration absorber is matched with the frequency of the controlled object by a response curve.
Detailed Description
In order that those skilled in the art will be able to fully practice the present invention, it will be further described with reference to the accompanying drawings and specific examples.
A multi-frequency dynamic vibration absorption method comprises the following steps of providing a vibration absorption material with rigidity KaAnd at least one of the fixing units has a rigidity KbIn the vibration absorbing unit of, wherein Ka>Kb. In the present embodiment, the rigidity KaAnd a stiffness KbEquivalent stiffness of the fixing unit and the vibration absorbing unit respectively, when Ka>KbWhen the controlled object vibrates, the fixed unit is slightly influenced by the fixed unit, and the vibration frequency of the controlled object is approximately and equivalently transmitted to the vibration absorption unit.
After the vibration absorption unit is rigidly connected to the fixing unit, the fixing unit is fixedly connected with the controlled object. In this embodiment, the controlled object and the fixing unit are rigidly connected, and the fixing unit and the vibration absorbing unit are fixedly connected, so that the connection stability gap between the controlled object, the fixing unit and the vibration absorbing unit can be ensured to be small, and the natural frequency of the vibration of the controlled object can be transmitted to the vibration absorbing unit almost equivalently. Meanwhile, the structure between the connection relations is simplified, and a plurality of unnecessary connection structural parts are simplified.
After the controlled object, the fixing unit and the vibration absorbing unit are connected, the vibration frequencies of the vibration absorbing unit and the controlled object are matched. In order to distribute the vibration absorbing units on the fixing unit as less as possible, the vibration absorbing unit is designed to have a fixed multi-order modal vibration frequency, the multi-order modal vibration frequency of the vibration absorbing unit is matched with a plurality of natural vibration frequencies of the controlled object, when the first-order modal vibration frequency of the vibration absorbing unit is equal to the natural vibration frequency of the controlled object, the natural vibration of the controlled object is absorbed by the vibration absorbing unit, and when all the natural vibration frequencies of the controlled object are equal to the various-order modal vibration frequencies of the vibration absorbing unit, the vibration of the controlled object is completely absorbed.
In order to realize the multi-order mode vibration on the vibration absorption unit, the vibration absorption unit is composed of the connecting part 8 and the mass block 4, so that the mass block 4 has three-order mode vibration. As shown in fig. 1, one end of the connecting part 8 is rigidly connected to the fixing unit, and the other end is rigidly connected to the mass 4 and has a rigid connection point a and a center of gravity O1So that the mass 4 generates up-and-down modal vibration x to the connecting part at the rigid connecting point A1。
The mass 4 has a center of gravity O2Center of gravity O1Arranged at a rigid connection point A and a center of gravity O2Wired external unit AO2O1Form an angle α therebetween, so that the mass 4 generates a torsional mode vibration ω around the connecting portion 81；
The mass 4 generates a center of mass modal vibration ω about the center of gravity O22(ii) a The up-down modal vibration x1Torsional mode vibration omega1And center of mass modal vibration omega2Forming third-order mode vibration. Through the arrangement of the relative fixed position relationship between the connecting part 8 and the mass block 4, the single vibration absorption unit has three-order modal vibration, and when the three modal vibration frequencies are reasonably matched and are the same as or close to the excitation frequency of the controlled object, the vibration response of the controlled object at the three frequencies can be effectively inhibited.
Based on the vibration absorption unit with the third-order modal vibration, n vibration absorption units are rigidly connected to the fixed unit, and each vibration absorption unit is rigidly connected with a point AnAnd center of gravity O2nAnd center of gravity O1nForm an angle αnAngle α of each of the abovenThe moment of the mass block 4 to the connecting part 8 is different, so that the torsional mode of each vibration absorption unitDynamic vibration omega1nThe natural frequencies are different;
setting the size or mass or rigidity of the connecting part 8 of each vibration absorbing unit to be unequal to each other, so that the upper and lower modal vibration x of each vibration absorbing unit1nAre not equal; setting the size or mass or stiffness of each mass block 4 to be unequal to each other so that the center of mass modal vibration ω of each vibration absorbing unit2nSo that the combination of the vibration absorbing units has a fixed multi-order modal vibration frequency. Calculation expression based on natural frequency
Figure DEST_PATH_IMAGE002A
When the connecting portion 8 or the mass 4 has different dimensions or masses, the equivalent mass m is also different, and the connecting portion 8 or the mass 4 has the upper and lower modal vibration x on the premise that the connecting portion 8 or the mass 4 has the same material1nAnd center of mass modal vibration omega2nShould be different, the up-and-down modal vibration x can be adjusted by adjusting and changing the size and mass of the connecting part 8 or the mass block 41nAnd center of mass modal vibration omega2nIs made to match the natural frequency of the controlled object. The stiffness of the connecting part 8 or the mass 4 also affects the up-down modal vibration x1nAnd center of mass modal vibration omega2nThe principle of the natural frequency of vibration is the same, and is not described herein.
Extracting a plurality of vibration frequencies fn most significant in the vibration response of the controlled object, and adjusting the angle αnOr adjusting the size, rigidity and mass of each connecting part 8 or adjusting the size or mass of each mass block 4 to enable the mass center modal vibration omega of at least one vibration absorption unit2nOr up and down modal vibration x1nOr torsional mode vibration omega1nIs equal to fn, whereby the multi-order modal vibration frequencies of the vibration absorbing unit are matched with the natural frequencies of the controlled object matching fn.
In the embodiment, when vibration reduction of multi-frequency vibration is performed, firstly, the vibration response condition of the controlled object is tested and analyzed, and the most significant vibration response is extractedThe design of the multi-frequency dynamic vibration absorber according to the frequency values f1, f2, … and fn mainly comprises the steps of reasonably matching the total mass and the mass distribution characteristics of each mass block 4, namely adjusting the mass and the size, the rigidity and the mass of the connecting part 8, and reasonably matching the space angle α between the mass block 4 and the connecting part 8n. In the present embodiment, a finite element method is used for design matching. The three significant modal frequencies of the dynamic vibration absorber can be expressed by the following expression:
when a finite element model of the dynamic vibration absorber is established, the total mass and the mass distribution of the mass 4, the length and the external dimension of the connecting part 8, and the angle α between the mass 4 and the connecting part 8nAll are design variables, and a plurality of characteristic values and modal frequencies of the dynamic vibration absorber can be matched through continuous iterative optimization.
As shown in fig. 2 and fig. 3, a multi-frequency dynamic vibration absorber includes at least one vibration absorbing unit and a fixing unit, wherein one end of the fixing unit is fixedly connected with a controlled object, the vibration absorbing unit includes a connecting portion 8 and a mass block 4, one end of the connecting portion 8 is rigidly connected with the fixing unit, the other end of the connecting portion 8 is rigidly connected with one end of the mass block 4 and has a rigid connection point a, and the connecting portion 8 and the mass block 4 form a certain space angle by taking the rigid connection point a as a vertex; the rigidity of the fixing unit is greater than that of the vibration absorbing unit.
The connecting part 8 is a cylindrical or cuboid rigid cantilever beam, one end of the cantilever beam is connected with one end of the mass block 4 through threads or is connected with the mass block through riveting, and the rigidity of the fixing unit is larger than that of the cantilever beam. In this embodiment, the cantilever beam is made of rigid materials such as stainless steel and aluminum alloy, the mass block 4 is made of stainless steel, aluminum alloy or cast iron, and the equivalent stiffness of the fixing unit is greater than the equivalent stiffness of the connecting part 8 and the mass block 4, so that the vibration frequency of the controlled object can be approximately equivalently transmitted to the connecting part 8 and the mass block 4, and the error influence during frequency matching is reduced. Generally, a steel wire rope is used as a cantilever beam material, so that not only can reasonable rigidity be matched, but also high damping can be provided for the dynamic vibration absorber, and the vibration energy consumption capability of the vibration absorber is improved.
In order to distribute the center of gravity of the mass 4 to the outside of the connecting portion 8 while consuming as little material as possible, the mass 4 is formed in a dumbbell shape having a large end size and a small middle size. In this embodiment, the mass 4 has a cubic shape at both ends and a cylindrical shape in the middle, and is integrally formed.
The fixing unit comprises a connecting thread 1, a fastening nut 2, a support column 3, a lower clamping plate 6 and an upper clamping plate 7; one end of the support column 3 is fixedly connected with a controlled object through the connecting thread 1 and the fastening nut 2, the other end of the support column is fixedly connected with the lower clamp plate 6 and the upper clamp plate 7, one end of the connecting portion 8 is clamped and fixed by the lower clamp plate 6 and the upper clamp plate 7, and the rigidity of the lower clamp plate 6 and the rigidity of the upper clamp plate 7 are larger than that of the connecting portion 8.
In this embodiment, the lower plate 6 is rigidly connected to the supporting column 3, the inner surfaces of the lower plate 6 and the upper plate 7 are provided with grooves having a semicircular cross section, the connecting portion 8 is engaged with the grooves of the upper and lower plates 6 and 7 through the outer surfaces thereof, and the clamping screw 10 clamps and fixes the lower plate 6 and the upper plate 7, thereby clamping and fixing the connecting portion 8.
In order to improve the damping energy dissipation capability of the dynamic vibration absorber, a restraining damping layer may be added to the surface of the connecting portion 8, as shown in fig. 4. The outer surface of the connecting portion 8 is covered with a constrained damping layer which comprises a first damping layer 11 and a second damping layer 12, the first damping layer 11 is made of a material easy to shear and deform and covers the outer surface of the connecting portion 8, and the second damping layer 12 is a thin plate made of a rigid material and covers the outer surface of the first damping layer 11. The damping layer 11 is made of rubber material or other high polymer damping material, and the constrained damping layer is made of stainless steel sheet. The vibration of the connecting part 8 drives the damping material 11 to move, and the damping layer 11 is subjected to shear deformation due to the limitation of the constrained damping layer 12, so that large damping is generated, and vibration energy is consumed.
In order to match and absorb a plurality of natural vibration frequencies of a controlled object, a plurality of vibration absorption units are fixedly connected with a fixed unit in a uniformly distributed mode through respective connecting parts 8, the rigidity, the mass and the size of the connecting parts 8 of the vibration absorption units are different, and the rigidity, the mass and the size of the mass blocks 4 of the vibration absorption units are different. In this embodiment, two vibration absorbing units are fixedly distributed on the fixing unit, and the structural forms of the mass block 4 and the mass block two 5 are the same, but the sizes and the masses are not necessarily the same, and can be changed according to actual needs. The sizes and the rigidities of the connecting part 8 and the connecting part two 9 are not necessarily the same, and the mass of each group of mass blocks and the rigidity of the cantilever beams can be matched according to the frequency tuning requirement, so that the natural frequency of each step of the dynamic vibration absorber is the same as or close to the vibration excitation frequency of the vibration main structure. The connection mode of each vibration absorption unit and the fixed unit adopts the same rigid connection mode.
By the multi-frequency dynamic vibration absorption method, the multi-frequency dynamic vibration absorber is adopted to perform frequency matching absorption on the controlled object, and various natural vibration frequencies of the controlled object can be well absorbed as shown in fig. 5. And the vibration absorption unit as a basic vibration absorption unit has third-order modal vibration, and compared with the multi-frequency dynamic vibration absorber in the prior art, the multi-frequency dynamic vibration absorber can reduce the distribution number of the vibration absorption units. The rigid connection between the vibration absorption unit and the fixing unit, and the relative position between the connecting part 8 and the mass block 4 in the vibration absorption unit are fixed, so that the structure is simplified, small parts are omitted, the connection between the structures is stable, and the error influence of frequency matching caused by the clearance play between the parts is reduced.
Obviously, the above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A multi-frequency dynamic vibration absorption method is characterized in that: comprising the steps of providing a beam having a stiffness KaAnd at least one of the fixing units has a rigidity KbIn the vibration absorbing unit of, wherein Ka>Kb；
Rigidly connecting the vibration absorption unit to the fixing unit;
fixedly connecting the fixed unit with the controlled object;
the vibration absorption unit has fixed multi-order modal vibration frequency, the multi-order modal vibration frequency of the vibration absorption unit is matched with a plurality of natural vibration frequencies of the controlled object, and when the first-order modal vibration frequency of the vibration absorption unit is equal to the natural vibration frequency of the controlled object, the natural vibration of the controlled object is absorbed by the vibration absorption unit.
2. The multi-frequency dynamic vibration absorbing method according to claim 1, wherein: the vibration absorption unit consists of a connecting part (8) and a mass block (4); one end of the connecting part (8) is rigidly connected with the fixed unit, the other end is rigidly connected with the mass block (4) and is provided with a rigid connecting point A and a gravity center O2So that the mass block (4) generates up-and-down modal vibration x to the connecting part by the rigid connecting point A1；
The mass (4) has a center of gravity O1Center of gravity O1Arranged at a rigid connection point A and a center of gravity O2Wired external unit AO2O1Form a certain angle α between them, so that the mass (4) can generate torsional mode vibration omega around the connecting part (8)1；
The mass (4) generates a center of mass modal vibration omega around a center of gravity O22(ii) a The up-down modal vibration x1Torsional mode vibration omega1And center of mass modal vibration omega2Forming third-order mode vibration.
3. The multi-frequency dynamic vibration absorbing method according to claim 2, wherein: the fixed unit is rigidly connected with n vibration absorption units, and each vibration absorption unit is rigidly connected with a point AnAnd center of gravity O2nAnd center of gravity O1nForm an angle αnAngle α of each of the abovenAre set to be unequal to each other so that the torsional mode vibration omega of each vibration absorbing unit1nThe natural frequencies are different;
setting the size or mass or stiffness of the connection part (8) of each vibration absorbing unit to be the sameAre not equal to each other, so that the up-and-down modal vibration x of each vibration absorption unit1nAre not equal;
setting the size or mass or stiffness of each mass block (4) to be unequal to each other so that the center of mass modal vibration omega of each vibration absorption unit2nSo that the combination of the vibration absorbing units has a fixed multi-order modal vibration frequency.
4. The multi-frequency dynamic vibration absorbing method of claim 3 wherein the most significant plurality of vibration frequencies fn in the vibration response of the controlled object are extracted by adjusting said angle αnOr adjusting the size, rigidity and mass of each connecting part (8) or adjusting the size, rigidity and mass of each mass block (4) to enable the mass center modal vibration omega of at least one vibration absorption unit to vibrate2nOr up and down modal vibration x1nOr torsional mode vibration omega1nIs equal to fn, whereby the multi-order modal vibration frequencies of the vibration absorbing unit are matched with the natural frequencies of the controlled object matching fn.
5. The utility model provides a multifrequency dynamic vibration absorber, includes at least one and shakes unit, a fixed unit, fixed unit one end and controlled object fixed connection, its characterized in that: the vibration absorption unit comprises a connecting part (8) and a mass block (4), one end of the connecting part (8) is rigidly connected with the fixing unit, the other end of the connecting part is rigidly connected with one end of the mass block (4) and is provided with a rigid connection point A, and the connecting part (8) and the mass block (4) form a certain space angle by taking the rigid connection point A as a vertex; the rigidity of the fixing unit is greater than that of the vibration absorbing unit.
6. The multi-frequency dynamic vibration absorber of claim 5 wherein: the connecting part (8) is a cylindrical or cuboid rigid cantilever beam, one end of the cantilever beam is connected with one end of the mass block (4) through threads or is connected with the mass block through riveting, and the rigidity of the fixing unit is larger than that of the cantilever beam.
7. The multi-frequency dynamic vibration absorber of claim 5 or 6, wherein: the mass block (4) has two larger end sizes and a smaller middle size and is in a dumbbell shape.
8. The multi-frequency dynamic vibration absorber of claim 7 wherein: the fixing unit comprises a connecting thread (1), a fastening nut (2), a support pillar (3), a lower clamping plate (6) and an upper clamping plate (7); support column (3) one end is through connecting thread (1), fastening nut (2) and controlled object fixed connection, the other end and lower plate (6) and punch holder (7) fixed connection, and lower plate (6) and punch holder (7) press from both sides tightly and fix connecting portion (8) one end, and the rigidity of lower plate (6) and punch holder (7) is greater than the rigidity of connecting portion (8).
9. The multi-frequency dynamic vibration absorber of claim 6 wherein: the outer surface of connecting portion (8) covers restraint damping layer, including damping layer one (11) and damping layer two (12), damping layer one (11) are made for the material of easy shear deformation and cover in the surface of connecting portion (8), and damping layer two (12) are the sheet metal that rigid material made and cover in the surface of damping layer one (11).
10. The multi-frequency dynamic vibration absorber of claim 8 wherein: the multiple vibration absorption units are fixedly connected with the fixing unit in an evenly distributed mode through respective connecting parts (8), the rigidity, the mass and the size of the connecting parts (8) of the vibration absorption units are different, and the rigidity, the mass and the size of the mass blocks (4) of the vibration absorption units are different.
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