Elastic metamaterial and method for improving vibration reduction performance thereof

Patent metadata

Field	Value
Publication number	US-11623772-B2
Application number	US-202117143980-A
Country	US
Kind code	B2
Filing date	Jan 7, 2021
Priority date	Jan 8, 2020
Publication date	Apr 11, 2023
Grant date	Apr 11, 2023

Abstract

The present invention relates to an elastic metamaterial for reducing vibrations of a flexible structure such as a main cable of a tether system for controlling an orbit of a satellite revolving around a planet, and a method for improving a vibration reduction performance thereof, and more particularly, to an elastic metamaterial having an improved precision, in which a ratio of a cross-sectional area of a pendulum ring may be adjusted to maintain a frequency characteristic other than a band gap generated due to the elastic metamaterial even in a state where a mass of the pendulum ring is not changed, and a band gap (R_ring) generated due to the pendulum ring of the elastic metamaterial and a band gap (R_beam) generated due to the elastic beams may be combined into one band gap to expand a vibration damping range, and a method for improving a vibration reduction performance thereof.

First claim

The invention claimed is:

1. An elastic metamaterial provided on a main cable and absorbing due to an external disturbance torque, the elastic metamaterial comprising:
a plurality of elastic beams having one ends connected to the main cable and extending downward in a divergent form; and
a pendulum ring connected to the other ends of the elastic beams and having a hollow portion through which the main cable penetrates so as to surround the main cable,
wherein a cross section of the pendulum ring has a rectangular shape having a transverse side and a longitudinal side having predetermined lengths.

2. The elastic metamaterial of claim 1 , wherein in the pendulum ring, a ratio between a length of the transverse side and a length of the longitudinal side is defined so as to maintain a predetermined cross-sectional area according to a predetermined resonance frequency band range.

3. The elastic metamaterial of claim 2 , wherein the length of the transverse side and the length of the longitudinal side of the pendulum ring according to the predetermined resonance frequency band range are defined by at least one of the following Equation 1 or 2:

f
i

=

i
⁡
(

i
2

-
1

)

2
⁢
π
⁢

R
2

(

i
2

+
1

)

1
/
2

[

E
⁢

I
y

m

]

1
/
2

Equation
⁢

1

f
i

=

i
⁡
(

i
2

-
1

)

2
⁢
π
⁢

R
2

[

E
⁢

I
x

m
⁡
(

i
2

+

EI
x

GC

)

]

1
/
2

Equation
⁢

2

(where I x : an area moment of inertia in a transverse direction, I y : an area moment of inertia in a longitudinal direction, f i : a unique frequency, i: a mode order, R: a radius of the pendulum ring, E: a Young's modulus, m: a mass per unit length, G: a shear modulus, and C: a torsional constant).

4. The elastic metamaterial of claim 2 , wherein the pendulum ring has a cross section of which the length of the transverse side is larger than the length of the longitudinal side.

5. The elastic metamaterial of claim 1 , further comprising a vibration control member provided on an outer surface of at least one of the main cable, the elastic beams, or the pendulum ring.

6. The elastic metamaterial of claim 5 , wherein the vibration control member is formed of a water-based vibration control paint having a predetermined damping ratio, and is applied to the outer surface of at least one of the main cable, the elastic beams, or the pendulum ring.

7. A method for improving a vibration reduction performance of the elastic metamaterial of claim 1 , the method comprising:
a frequency moving step of moving a band gap of a resonance frequency of the main cable by adjusting a ratio between a length b of the transverse side and a length h of the longitudinal side of the pendulum ring, the band gap being generated from the pendulum ring.

8. The method of claim 7 , wherein in the frequency moving step, the ratio between the length of the transverse side and the length of the longitudinal side is adjusted so as to maintain

Assignees

• Univ Yonsei Iacf

Inventors

• Park No-Cheol
• Yoon Joo Young

Classifications

• F16F15/02 Primary

  Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems ({F16F15/005 takes precedence } ; layered products B32B; suppression of vibration in ships B63; {relieving load on bearings, using magnetic means F16C39/06}) · CPC title

• F16F2224/02

  solids · CPC title

• F16F2228/063

  Negative stiffness · CPC title

• F16F7/10

  using inertia effect (F16F13/108, F16F13/22, F16F15/10, F16F15/22 take precedence; stabilising vehicle bodies by means of movable masses B62D37/04; protection of buildings against vibrations or shocks by mass dampers E04H9/0215; arrangements or devices for damping mechanical oscillations of power lines H02G7/14) · CPC title

• B64G1/648 Primary

  Tethers · CPC title