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This paper discusses the experimental verification of a smart passive control system based on MR dampers. The system utilizes electromagnetic induction technology and has proven to be energy efficient and comparable to optimal passive control.
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The 18th KKCNN Symposium Experimental Study onSmart Passive System Based on MR Damper December 20. 2005 Department of Civil & Environmental Engineering Korea Advanced Institute of Science and Technology. Jung-Hyun Hong, Graduate Student, KAIST, Korea Kang-Min Choi, Ph.D. Candidate, KAIST, Korea Jong-Heon Lee, Professor, Kyungil University, Korea Ju-Won Oh, Professor, Hannam University, Korea In-Won Lee, Professor, KAIST, Korea
Contents CONTENTS • Introduction • Smart Passive Control System • Experimental Verification • Conclusions
Introduction Introduction • Semiactive MR Dampers • Viscous fluid out of magnetic field • Solid-like in a magnetic field • Proportional strength to magnitude of magnetism • Magnetorheological (MR) fluid Without Magnetic Fields With Magnetic Fields
Introduction • MR fluid damper • Damping coefficient depending on electric current • Requirements : External power for current supply Sensors for feedback control Limitation for large-scale structures
Cho, S.W., Jung, H.J., Lee, I.W. (2005) “Smart passive system based on magnetorheological damper.”Smart Materials and Structures, 14, 707-714. • Change characteristics of MR damper with electromagnetic induction (EMI) system • Control without external power and control algorithm Introduction • Smart Passive Control System Need for experimental verification
Smart Passive Control System Smart Passive Control System • EMI System for MR Damper • Faraday’s law of electromagnetic induction (1) : Electromotive force (EMF) N : Number of turns of coil : Magnetic flux B : Magnetic field A : Area of cross section
MR Damper induced current magnetic field damper deformation EMI system Smart Passive Control System • Schematic of the Smart Passive System Faster MR damper movement Higher EMF EMI system is a source of power supply and has adaptability.
EMI system MR damper V DAQ Board Computer Performance Verification Performance Verification • Experimental Setup
Performance Verification • 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%
Performance Verification • MR damper • MR controllable friction damper (RD-1097-01, Lord Corporation) • Maximum force level: 100 N • Maximum command current: 0.5 A
Performance Verification • EMI system Magnets Solenoid
Solenoid Magnetic Field Change of Area Movement of Solenoid Performance Verification • Electromotive force (EMF) (2) (3) • Magnetic field: • Width of magnets: • Number of turns:
Performance Verification • Input Ground Motion • Time scale: 2 times the recorded rate • Amplitude scale: 40% El Centro earthquake (PGA: 0.1395 g) 20% El Centro earthquake (PGA: 0.0697 g) 30% Hachinohe earthquake (PGA: 0.0811 g) 20% Kobe earthquake (PGA: 0.1643 g) 10% Northridge earthquake (PGA: 0.0843 g)
Performance Verification • 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
Performance Verification • Optimal Passive Control System • Scaled El Centro earthquake (0.14 g) Sum of normalized values Normalized value Optimal Jd1 Jd2 Ja1 Ja3 Passive voltage value (V) Passive voltage value (V) Optimal passive voltage : 0.85 V
Performance Verification • Results • Scaled El Centro earthquake (0.14 g) d2 (mm) a3 (m/s2) Voltage (V) Time (sec)
Performance Verification • Performance comparisons Normalized maximum interstory drifts
Performance Verification Normalized value Passive off Passive on Optimal Smart passive passive • Better than the passive off case • Similar to the optimal passive case
Performance Verification Normalized maximum accelerations
Performance Verification Normalized value Passive off Passive on Optimal Smart passive passive • Better than the passive on case • narrow range of responses
Performance Verification • Dissipated electric energy Smart passive system has the bestenergy efficiency.
Conclusions Conclusions • 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.
Conclusions • Performance verification • Smart passive systemis significantly better than passive off and passive on cases. • Smart passive systemis comparable with optimal passive case. : It is highly energy efficient. • Smart passive system is thesuperior control device.
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