JP7401908B2 - Vibration damping device - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies July 1, 2020 https://www. akita-pu. ac. jp/system/me/tomioka/index. html https://www. akita-pu. ac. jp/system/me/tomioka/Tomioka Laboratory Introduction 20190515_p3. pdf https://www. akita-pu. ac. jp/system/me/tomioka/researches/index. html February 20, 2020 1st Yuri Honsho Techno Net April 1, 2020 https://www. akita-pu. ac. jp/system/me/tomioka/index. html https://www. akita-pu. ac. jp/system/me/tomioka/1st %20 Yuri Sho Techno Net Poster Presentation 20200220_Higuchi. pdf

The present invention relates to a vibration damping device that reduces noise and elastic vibration generated from a structure.

BACKGROUND ART Noise and elastic vibration generated by the structures are considered problems in structures such as railway vehicles and aircraft that are required to be fast and lightweight. As one type of vibration reduction device that reduces noise and elastic vibration generated from structures, a dynamic vibration absorber that utilizes an elastic vibration mode caused by horizontal elastic deformation of a viscoelastic body has been proposed (for example, Non-Patent Document 1). reference).

Michel Azoulay, Alexander Veprik, Vladimir Babitsky and Neil Halliwell, Distributed absorber for Noise and vibration Control, Shock and Vibration, Shock and Vibration 18 (2011) 181-219 DOI 10.3233/SAV20100608 IOS Press

However, conventional technology utilizes an elastic vibration mode caused by horizontal elastic deformation of an elastic body, and it is difficult to arbitrarily adjust the natural frequency of the elastic vibration mode. It is difficult to construct a vibration damping device that reduces the elastic vibrations of general structures with different vibration frequencies. In addition, since the elastic vibration of a structure has many natural vibration modes, effective vibration reduction requires damping multiple natural vibration modes at the same time, but the elastic vibration modes can be adjusted arbitrarily. Therefore, it is difficult to damp multiple natural vibration modes simultaneously.

The present invention has been made in view of the above problems, and provides a vibration damping device that can solve the above problems and realize multi-mode vibration damping that simultaneously damps a plurality of natural vibration modes of a structure. The purpose is to provide

In order to solve the above problems, the present invention has the following configuration.
The vibration damping device of the present invention includes a mass body embedded in a viscoelastic body.multipleVibration damperand,
a support body having holes formed therein for accommodating each of the plurality of vibration damping bodies;It is characterized in that the natural frequencies of the plurality of damping bodies are divided into values corresponding to two or more natural frequencies of a structure to be damped.
Furthermore, the vibration damping device of the present invention is characterized in that the support body is made of a material that does not deform.
Furthermore, in the vibration damping device of the present invention, the natural frequency of the vibration damping body may be adjusted by a combination of the size or mass of the mass body and the size or material properties of the viscoelastic body. .
Furthermore, in the vibration damping device of the present invention, each of the viscoelastic bodies in the plurality of vibration dampers has the same material properties,
The natural frequency of the damping body may be adjusted by a combination of the size of the mass body and the size of the viscoelastic body.
Furthermore, in the vibration damping device of the present invention, the mass body may be embedded in the viscoelastic body so as to be able to vibrate in three-dimensional directions.
Furthermore, in the vibration damping device of the present invention, the viscoelastic body and the mass body may be spherical bodies.
Further, the vibration damping device of the present invention includes a vibration damping body configured by a mass body embedded in a viscoelastic body, and a support body in which a hole for accommodating the vibration damping body is formed, and the mass body is embedded in the viscoelastic body so as to be able to vibrate in three-dimensional directions, and the size of the viscoelastic body or the mass body varies depending on the direction in which the mass body vibrates, and the size of the viscoelastic body or the mass body varies depending on the direction in which the mass body vibrates in multiple directions. Characterized by independently adjusted natural frequencies.

Since the present invention is configured as described above, the natural frequencies of the plurality of damping bodies 10 can be easily set according to two or more natural frequencies of the structure 20 to be damped. Therefore, it is possible to realize multi-mode vibration damping that simultaneously damps a plurality of natural vibration modes of the structure 20.

1 is a perspective view showing the configuration of an embodiment of a vibration damping device according to the present invention. FIG. 2 is an explanatory diagram illustrating the correspondence between the vibration damping device and the dynamic vibration reducer shown in FIG. 1. FIG. It is a figure showing the numerical calculation model of the damping device concerning the present invention. FIG. 4 is a diagram showing the relationship between the natural frequency of the damping body shown in FIG. 3 and the size (mass) of the viscoelastic body and the mass body. FIG. 4 is a diagram showing a change in the natural frequency when the diameter of the mass body of the damping body shown in FIG. 3 is changed. 2 is a diagram showing an example of a structure whose vibration is damped by the vibration damping device shown in FIG. 1. FIG. FIG. 2 is a diagram showing a demonstration example of the damping effect of the damping device shown in FIG. 1; It is a perspective view showing the composition of other embodiments of the damping device concerning the present invention.

Next, modes for carrying out the present invention (hereinafter simply referred to as "embodiments") will be specifically described with reference to the drawings.
Referring to FIG. 1, the vibration damping device 1 of the present embodiment includes a plurality of vibration damping bodies 10 (10a, 10b) each including a viscoelastic body 2 and a mass body 3 embedded in the viscoelastic body 2. , a support body 4 that supports a plurality of damping bodies 10 (10a, 10b).

Both the viscoelastic body 2 and the mass body 3 are spherical bodies, and the mass body 3 is embedded in the viscoelastic body 2 so that their centers coincide with each other. The plurality of damping bodies 10 (the viscoelastic bodies 2 in which the mass bodies 3 are embedded) are each housed in a plurality of spherical internal spaces having substantially the same diameter as the viscoelastic bodies 2.

The viscoelastic body 2 is made of a known material (such as an elastomer) having viscosity and elasticity, and can be made of, for example, natural rubber, urethane rubber, silicone gel, or the like. As shown in FIG. 2, the viscoelastic body 2 plays a role corresponding to a spring k supporting a mass m and a damper c in a dynamic vibration absorber.

The mass body 3 is made of a material having a mass that can vibrate when embedded in the viscoelastic body 2, and as shown in FIG. 2, in the dynamic vibration absorber, the mass m supported by the spring k and the damper c plays a role as The mass body 3 can be made of metal such as iron, for example.

The support body 4 is made of a non-deformable material such as epoxy resin.

In this embodiment, the viscoelastic body 2 is composed of an upper hemisphere and a lower hemisphere, and the support body 4 is composed of an upper case and a lower case in which hemispherical holes are both formed. There is. The mass body 3 is embedded in the center of the viscoelastic body 2 by attaching the upper case and the lower case, in which the upper hemisphere and the lower hemisphere are housed in holes, respectively, with the mass body 3 interposed therebetween.

As shown in FIG. 2, the mass body 3 plays a role as a mass m in the dynamic vibration absorber, and the viscoelastic body 2 plays a role as a spring k and a damper c in the dynamic vibration absorber. . That is, the vibration damper 10 functions as a dynamic vibration absorber in which a spherical mass body 3 embedded in the center of a spherical viscoelastic body 2 vibrates in multiple directions. Then, the mass body 3 vibrates in any direction at the same natural frequency.

The natural frequencies of the vibration damping body 10a and the vibration damping body 10b are adjusted so as to act as dynamic vibration absorbers for different natural frequencies of the structure 20 to be damped. Achieves multi-mode vibration suppression that suppresses vibration modes simultaneously. That is, the natural frequencies of the plurality of damping bodies 10 are divided into values corresponding to two or more natural frequencies of the structure 20 to be damped. Note that in this embodiment, the damping device 1 is configured with two damping bodies 10 each adjusted to two different natural frequencies, but three or more damping bodies 10 each adjusted to three or more different natural frequencies The vibration damping body 10 may be configured as follows. It is also possible to provide two or more damping bodies 10 adjusted to the same natural frequency.

The natural frequency of the damping body 10 is determined by the combination of the sizes (mass) of the viscoelastic body 2 and the mass body 3, or the material properties such as viscosity and elasticity (viscoelastic properties) of the viscoelastic body 2 and the mass body 3. It can be adjusted by combining the sizes (mass).

Refer to FIGS. 3 and 4 below for the analysis results of the influence of the size (mass) of the viscoelastic body 2 and the mass body 3 on the vibration characteristics of the damping body 10 when the material properties of the viscoelastic body 2 are taken as the material properties. This will be explained in detail.

As shown in FIG. 3, a numerical calculation model in which a damping device 1a including one damping body 10 is fixed on a vibration table 30, and the center of the vibration table 30 is vibrated vertically at 1N is It was constructed using general-purpose finite element method software. Then, the dimensions of the support body 4a are fixed to 50 mm in length, 50 mm in width, and 50 mm in height, one dimension of the diameter of the viscoelastic body 2 and the diameter of the mass body 3 is kept constant, and the other dimension is changed to generate natural vibrations. An analysis was performed.

FIG. 4(a) shows the change in the natural frequency when the diameter of the mass body 3 is fixed at 15 mm and the diameter of the viscoelastic body 2 is changed. According to this, when the diameter of the mass body 3 is fixed, the natural frequency tends to decrease as the diameter of the viscoelastic body 2 increases.

Moreover, FIG. 4(b) shows the change in the natural frequency when the diameter of the viscoelastic body 2 is fixed at 30 mm and the diameter of the mass body 3 is changed. According to this, when the diameter of the viscoelastic body 2 is fixed, the natural frequency tends to decrease as the diameter of the mass body 3 increases. Note that when the diameter of the mass body 3 is larger than 15 mm, the natural frequency becomes large. However, this is considered to be because as the diameter of the mass body 3 increases, the thickness of the viscoelastic body 2 decreases, and the spring constant increases relatively.

From the results of the above numerical analysis, it can be confirmed that if the material properties are the same, the natural frequency of the damper 10 changes in a fixed direction depending on the dimensions of the viscoelastic body 2 and the mass body 3. This makes it possible to design the vibration damping device 1 according to the natural frequency of the structure 20 to be damped.

Next, a structure with natural frequencies of 1st mode: 24.5Hz, 2nd mode: 67.7Hz, 3rd mode: 125.6Hz, 4th mode: 187.1Hz, and 5th mode: 239.3Hz. A method of adjusting the vibration damping device 1 using the vibration damping device 20 will be described in detail with reference to FIGS. 5 to 7.

First, the change in the natural frequency when the diameter of the mass body 3 or the diameter of the viscoelastic body 2 is fixed and the diameter of the other viscoelastic body 2 or the diameter of the mass body 3 is changed is investigated. In this embodiment, the change in the natural frequency was investigated when the diameter of the viscoelastic body 2 was fixed at 50 mm and the diameter of the other mass body 3 was changed. FIG. 5 shows the results of the frequency response function (FRF), and the peak moves to lower frequencies as the diameter of the mass body 3 becomes larger.

Then, based on the investigated natural frequency, the diameter of the mass body 3 corresponding to the natural frequency of the viscoelastic body 2 to be damped is specified. In this embodiment, the mass body 3 is 30 mm and 15 mm at which the FRF peaks around 125.6 Hz and 187.1 Hz of the 3rd mode and 4th mode of the natural frequency of the viscoelastic body 2 to be damped. The diameter of That is, the third-order mode and the fourth-order mode were targeted for vibration suppression.

The vibration damping body 10a has a diameter of the viscoelastic body 2 of 50 mm and a diameter of the mass body 3 of 30 mm, and a diameter of the viscoelastic body 2 of 50 mm and a diameter of the mass body 3 of 15 mm. A damping device 1 was manufactured using the damping body 10b, and the damping effect was verified.

As shown in FIG. 6, the structure 20 to be damped was a 1/10 scale underframe model of a railway vehicle with a longitudinal length of 2000 mm, a width of 300 mm, and a weight of 10 kg. Then, a point 300 mm from the front and rear tips is supported by a pillow spring, and the center of the front end is set as an excitation point. Then, the damping device 1 was mounted so that the centers of the damping bodies 10a and 10b were located at a position 1240 mm from the front end, and the center of 1390 mm from the tip was taken as the measurement point.

The excitation signal was a random wave (band random wave) passed through a band pass filter with cutoff frequencies of 5 Hz and 400 Hz, and the excitation was performed for 60 seconds. Then, the sampling frequency was set to 4000 Hz, and the acceleration (response acceleration) at the measurement point was AD converted, and the FRF of the response acceleration to the force (excitation force) measured at the excitation point was determined.

FIG. 7 shows the FRF at the measurement point, where the dotted line shows the measurement results for only the structure 20, the solid line shows the measurement results when the damping device 1 is installed, and the dashed line shows the rigid body of the same mass as the damping device 1. The measurement results are shown when a certain amount of mass is loaded. Referring to FIG. 7, the peaks of the 3rd mode and 4th mode targeted for vibration damping are lower when the damping device 1 is installed compared to when only the structure 20 and the rigid mass are installed. I can read that. Therefore, multi-mode vibration damping can be expected by mounting a plurality of damping bodies 10 (10a, 10b) each adjusted to different natural frequencies of the structure 20 to be damped.

In this way, the relationship between the size (mass) of the mass body 3 and the natural frequency when the diameter of the viscoelastic body 2 is constant is investigated in advance, and the multiple natural frequencies of the structure 20 to be damped are determined. When multiple sizes (mass) of the corresponding mass bodies 3 are specified, the mass bodies 3 of multiple sizes (mass) are dispersed and embedded in the sheet-like (or plate-like) viscoelastic body 2a to damp vibration. It is also possible to configure a device 1b. By combining the characteristics of the viscoelastic body 2 and the mass, size, etc. of the mass body 3, a damping effect can be obtained in a wide frequency band. Note that embedding in a dispersed manner means embedding at intervals that do not affect the vibrations of other mass bodies 3.

In this case, the vibration damping device 1b can be handled as a sheet-like viscoelastic body 2a. Therefore, if the structure 20 to be damped is plate-shaped, multimode damping can be achieved simply by placing the damping device 1b on the structure 20 as it is. Furthermore, when the structure 20 to be damped has a double panel structure such as the body of a railway vehicle, multi-mode damping can be achieved simply by filling the gap with the damping device 1b. Furthermore, if the structure 20 to be damped is part of the interior material of a building (such as a wall or ceiling board), multi-mode vibration damping can be achieved simply by gluing the damping device 1b to the back of the panel. can. In this way, the damping device 1b has a high degree of freedom when applied to the actual structure 20. Furthermore, the vibration damping device 1b is also effective in reducing sound (solid-borne sound) caused by vibrations transmitted through the structure and radiated from walls and the like.

In the above description, the mass body 3 is assumed to be a sphere, but the mass body 3 may have a shape that varies in size depending on the vibration direction of the mass body 3, for example, an elliptical sphere or a rugby ball shape. Similarly, the viscoelastic body 2 may also have a shape that varies in size (thickness) depending on the vibration direction of the mass body 3, for example, an elliptical sphere or a rugby ball shape. In these cases, the natural frequencies of vibrations in the viscoelastic body 2 of the mass body 3 in multiple directions (for example, up and down, left and right, front and back) can be adjusted independently.

As explained above, in this embodiment, the mass body 3 functioning as the mass of the dynamic vibration absorber is embedded in the viscoelastic body 2 functioning as the spring k and damper c of the dynamic vibration absorber. A plurality of vibration bodies are provided, and the natural frequencies of the plurality of vibration damping bodies 10 are assigned to values corresponding to two or more natural frequencies of the structure 20 to be damped.
With this configuration, the natural frequencies of the plurality of damping bodies 10 can be easily set according to two or more natural frequencies of the structure 20 to be damped, and the plurality of natural frequencies of the structure 20 can be easily set. It is possible to achieve multi-mode vibration damping that simultaneously damps natural vibration modes.

Furthermore, in the present embodiment, the natural frequency of the damper 10 is adjusted by a combination of the size or mass of the mass body 3 and the size or material properties of the viscoelastic body 2.
With this configuration, the natural frequency of the damping body 10 can be easily adjusted.

Furthermore, in the present embodiment, each of the viscoelastic bodies 2 in the plurality of damping bodies 10 has the same material properties, and the natural frequency of the vibration damping body 10 is determined by the size of the mass body 3 and the viscoelastic body 2. It is adjusted in combination with the size of body 2.
With this configuration, the natural frequency of the damping body 10 can be adjusted more easily by simply changing the size of the mass body 3 or the viscoelastic body 2.

Furthermore, in this embodiment, the mass body 3 is embedded in the viscoelastic body 2 so as to be able to vibrate in three-dimensional directions.
With this configuration, the mass body 3 can vibrate in multiple directions within the viscoelastic body 2, and a damping effect against vibrations in multiple directions can be obtained.

Furthermore, in this embodiment, the viscoelastic body 2 and the mass body 3 are spheres.
With this configuration, the mass body 3 vibrates at the same natural frequency in any direction, so that the natural frequency can be easily adjusted.

Furthermore, in this embodiment, the size of the viscoelastic body 2 or the mass body 3 differs depending on the vibration direction of the mass body 3.
With this configuration, the natural frequencies of vibrations in multiple directions in the viscoelastic body 2 of the mass body 3 can be adjusted independently. For example, by making the shape of the viscoelastic body 2 or the mass body 3 into an elliptical sphere or a rugby ball shape, the natural frequency can be adjusted independently according to the vibration direction of the mass body 3.

Furthermore, in this embodiment, a support body 4 that supports a plurality of damping bodies 10 is provided.
With this configuration, mounting on the structure 20 can be easily performed.

Further, in this embodiment, a plurality of mass bodies 3 are embedded in a distributed manner in the viscoelastic body 2a, and the natural frequency of the vibration of the mass body 3 in the viscoelastic body 2 is determined depending on the size of the mass body 3. , are divided into values corresponding to two or more natural frequencies of the structure 20 to be damped.
With this configuration, the natural frequencies of the plurality of damping bodies 10 can be easily set according to two or more natural frequencies of the structure 20 to be damped, and the plurality of natural frequencies of the structure 20 can be easily set. It is possible to achieve multi-mode vibration damping that simultaneously damps natural vibration modes.

Furthermore, in this embodiment, the viscoelastic body 2a is sheet-like or plate-like.
With this configuration, the damping device 1a can be treated as a sheet-like viscoelastic body 2a, so there is a high degree of freedom when applying it to the actual structure 20, and it is also effective in reducing sound (solid-borne sound). do.

1, 1a, 1b Vibration damping device 2, 2a Viscoelastic body 3 Mass body 4, 4a Support body 10, 10a, 10b Vibration damping body 20 Structure 30 Vibration table

Claims (7)

a plurality of damping bodies configured by a mass body embedded in a viscoelastic body;
a support body in which a hole is formed for accommodating each of the plurality of vibration damping bodies,
A vibration damping device characterized in that the natural frequencies of the plurality of damping bodies are divided into values corresponding to two or more natural frequencies of a structure to be damped. The vibration damping device according to claim 1 , wherein the support body is made of a material that does not deform . 3. The natural frequency of the damping body is adjusted by a combination of the size or mass of the mass body and the size or material properties of the viscoelastic body. vibration damping device. Each of the viscoelastic bodies in the plurality of vibration damping bodies has the same material properties,
The vibration damping device according to any one of claims 1 to 3 , wherein the natural frequency of the vibration damping body is adjusted by a combination of a size of the mass body and a size of the viscoelastic body. . The vibration damping device according to any one of claims 1 to 4, wherein the mass body is embedded in the viscoelastic body so as to be able to vibrate in a three-dimensional direction. The vibration damping device according to claim 5, wherein the viscoelastic body and the mass body are spherical bodies. a vibration damper configured by a mass body embedded in a viscoelastic body;
a support body in which a hole for accommodating the vibration damping body is formed;
The mass body is embedded in the viscoelastic body so as to be able to vibrate in three-dimensional directions,
The vibration damping device is characterized in that the size of the viscoelastic body or the mass body varies depending on the direction in which the mass body vibrates, and the natural frequencies of vibrations of the mass body in multiple directions are adjusted independently. Device.

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