Structural Dynamics & Vibration Control Lab 1 December 20. 2005 Department of Civil & Environmental Engineering K orea A dvanced I nstitute of S cience

Structural Dynamics & Vibration Control LabStructural Dynamics & Vibration Control Lab 11

December 20. 2005

Department of Civil & Environmental EngineeringDepartment of Civil & Environmental EngineeringKorea Advanced Institute of Science and Technology.

Experimental Study onExperimental Study onSmart Passive System Based on MR DamperSmart Passive System Based on MR Damper

The 18th KKCNN Symposium

Jung-Hyun Hong, Graduate Student, KAIST, KoreaKang-Min Choi, Ph.D. Candidate, KAIST, KoreaJong-Heon Lee, Professor, Kyungil University, KoreaJu-Won Oh, Professor, Hannam University, KoreaIn-Won Lee, Professor, KAIST, Korea


CONTENTS CONTENTS

I.I. IntroductionIntroduction

II.II. Smart Passive Control SystemSmart Passive Control System

III.III. Experimental VerificationExperimental Verification

IV.IV. ConclusionsConclusions

Contents


- Viscous fluid out of magnetic field

- Solid-like in a magnetic field

- Proportional strength to magnitude of magnetism

Magnetorheological (MR) fluid

IntroductionIntroduction Semiactive MR Dampers

Introduction

Without Magnetic FieldsWithout Magnetic Fields With Magnetic FieldsWith Magnetic Fields


- Damping coefficient depending on electric current

- Requirements : External power for current supply

Sensors for feedback control

MR fluid damper

Introduction

Limitation for large-scale structuresLimitation for large-scale structures


Introduction

Cho, S.W., Jung, H.J., Lee, I.W. (2005) “Smart passive syste

m based on magnetorheological damper.” Smart Materials a

nd Structures, 14, 707-714.

- Change characteristics of MR damper

with electromagnetic induction (EMI) system

- Control without external power and control algorithm

Need for experimental verificationNeed for experimental verification

Smart Passive Control System


Faraday’s law of electromagnetic induction

Smart Passive Control SystemSmart Passive Control System EMI System for MR Damper


dt

dABN

dtN BdΦ

: Electromotive force (EMF)

N : Number of turns of coil

: Magnetic flux

B : Magnetic field

A : Area of cross section

BΦ

(1)



Faster MR damper movement Higher EMF

EMI system is a source of power supply

and has adaptability.

MR Damper

damper deformation

magnetic field

inducedcurrent

EMI system

Schematic of the Smart Passive System


Performance VerificationPerformance Verification Experimental Setup

Performance Verification

V

3x

11, xx

f

1x

gx

2x

bx

DAQ BoardComputer

VMR damper EMI system



Shear building model

- Height: 105 cm

- Total weight: 52.34 kg

- First three natural frequencies : 2.05, 5.55, 8.41 Hz

- Damping ratio: 0.7%

- Height: 105 cm

- Total weight: 52.34 kg

- First three natural frequencies : 2.05, 5.55, 8.41 Hz

- Damping ratio: 0.7%



MR damper

- MR controllable friction damper (RD-1097-01, Lord Corporation)

- Maximum force level: 100 N

- Maximum command current: 0.5 A

- MR controllable friction damper (RD-1097-01, Lord Corporation)

- Maximum force level: 100 N

- Maximum command current: 0.5 A



EMI system

Magnets

Solenoid



- Electromotive force (EMF)- Electromotive force (EMF)

Magnetic Field

Solenoid

Movementof Solenoid

Change of Area

x

w

dt

dABN

wBNK emf

(2)

(3)

- Magnetic field:

- Width of magnets:

- Number of turns:

- Magnetic field:

- Width of magnets:

- Number of turns:

TB 5.0

cmw 5

dt

dxwBN

dt

dxK emf

1840N



Input Ground Motion

- Time scale: 2 times the recorded rate

- Amplitude scale:

40% El Centro earthquake (PGA: 0.1395 g)


30% Hachinohe earthquake (PGA: 0.0811 g)

20% Kobe earthquake (PGA: 0.1643 g)

10% Northridge earthquake (PGA: 0.0843 g)



30% Hachinohe earthquake (PGA: 0.0811 g)

20% Kobe earthquake (PGA: 0.1643 g)

10% Northridge earthquake (PGA: 0.0843 g)


Experimental Results


Evaluation Criteria

- Jd1 : normalized maximum interstory drift between the base and 1st floors

- Jd2 : normalized maximum interstory drift between the 1st and 2nd floors

- Ja1 : normalized maximum 1st floor acceleration

- Ja3 : normalized maximum 3rd floor acceleration


0.0

0.2

0.4

0.6

0.8

1.0

0.5 1 1.5

d₁ d₂

a₁ a₃


Optimal Passive Control System- Scaled El Centro earthquake (0.14 g)

Passive voltage value (V)

Nor

mal

ized

val

ue

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.5 1 1.5Passive voltage value (V)

Optimal

Optimal passive voltage : 0.85 V

Sum of normalized values

Jd1 Jd2

Ja1 Ja3


- Scaled El Centro earthquake (0.14 g)


0

0.3

0.6

0.9

1.2

1.5

1.8

0 5 10 15 20 25

-30

-20

-10

0

10

20

30

0 5 10 15 20 25

UncontrolledSmart passive control

-6

-4

-2

0

2

4

6

0 5 10 15 20 25

UncontrolledSmart passive control

Time (sec)

d2 (

mm

) a 3 (

m/s

2 )

Vol

tage

(V

) Results


- Performance comparisons


Normalized maximum interstory drifts

El Centro

(0.14 g)

El Centro

(0.07 g)

Hachinohe

(0.08 g)

Kobe

(0.16 g)

Northridge

(0.08 g)

Passive off 0.77 0.48 0.50 0.86 0.90

Passive on 0.49 0.63 0.40 0.41 0.82

Optimal passive

0.42 0.43 0.36 0.68 0.77

Smart passive

0.53 0.45 0.40 0.72 0.84



0.00

0.20

0.40

0.60

0.80

1.00

Pass ive off Pass ive on Optimal pass ive Smart pass ive

El Centro (0.14g)El Centro (0.07g)Hachinohe (0.08g)Kobe (0.16g)Northridge (0.08g)

Nor

mal

ized

val

ue

Optimal Smart passive passive

Passive off Passive on

- Better than the passive off case

- Similar to the optimal passive case



Normalized maximum accelerations

El Centro

(0.14 g)

El Centro

(0.07 g)

Hachinohe

(0.08 g)

Kobe

(0.16 g)

Northridge

(0.08 g)

Passive off 0.72 0.47 0.45 0.71 0.72

Passive on 0.79 1.00 0.46 0.60 1.13

Optimal passive

0.52 0.65 0.31 0.42 0.79

Smart passive

0.64 0.46 0.36 0.63 0.64


0.00

0.20

0.40

0.60

0.80

1.00

1.20

Passive off Passive on Optimal passive Smart passive

El Centro (0.14g)El Centro (0.07g)Hachinohe (0.08g)Kobe (0.16g)Northridge (0.08g)


Nor

mal

ized

val

ue

Optimal Smart passive passive

Passive off Passive on

- Better than the passive on case

- narrow range of responses


- Dissipated electric energy


Passive off Passive onOptimal

passive

Smart

passive

Energy

(mJ/sec)0 720 96 0

Smart passive system has the best energy efficiency. Smart passive system has the best energy efficiency.


- Smart passive control system is based on

electromagnetic induction (EMI) using MR damper.

- The EMI system takes a role of power supply and has adaptability.

- Smart passive control system is based on

electromagnetic induction (EMI) using MR damper.

- The EMI system takes a role of power supply and has adaptability.

ConclusionsConclusions

Conclusions


Conclusions

Performance verification

- Smart passive system is significantly better

than passive off and passive on cases.

- Smart passive system is comparable

with optimal passive case.

: It is highly energy efficient.

- Smart passive system is significantly better

than passive off and passive on cases.

- Smart passive system is comparable

with optimal passive case.

: It is highly energy efficient.

Smart passive system is the superior control device. Smart passive system is the superior control device.


Thank YouThank You

for Your Attentionfor Your Attention

Documents

Structural Dynamics & Vibration Control Lab 1 December 20. 2005 Department of Civil & Environmental Engineering K orea A dvanced I nstitute of S cience