Embed Size (px)
DESCRIPTION
Information on Vibration Isolation System
Citation preview
Vibration Isolation SystemsBY PRINCESS J. THOMAS
Vibration
Unwanted part of society
Causes imbalance, noise, waste of energy and failure in machine parts
Two types of unwanted vibration:
Ground Vibration – vibration transmitted from the ground through suspension
Direct Disturbance – vibration caused by disturbances acting on an isolation table
Two solutions:
Passive Vibration Isolation
Active Vibration Isolation
Passive Vibration Isolation
Simple
Purely Mechanical
Springs – softens vibration
Dampers – terminates the oscillation in the system
Must be calibrated correctly for the required function
Negative Spring Stiffness Mechanism
New revolutionary concept
Magnets in attracting configuration (Carella et al.)
Compact spring to produce negative stiffness (Lee at al.)
Simple 6-DOF system consisting of a vertical-motion isolator, horizontal-motion isolator and a tilt-motion isolator (Platus)
Vertical-Motion Isolator
Spring KS
Two fixed flexures
Compressive force P to create negative stiffness KN
Equation can be made to approach zero when weight is applied
Horizontal-Motion Isolator
Placed on top of vertical-motion isolator
Consists of two fixed-free column
Behaves similarly to horizontal spring and a negative spring mechanism
Passive Vibration Isolator
Active Vibration Isolation System
Accommodates for 6-DOF most of vibration
Translational in x, y and z planes
Rotational – roll, pitch and yaw
More accurate than passive isolators
No resonance in active system
Active Vibration Isolation System
Spring connected to Active Vibration Control (AVC) system
Feedback circuit consists of:
Piezoelectric Accelerometer
Analogue Control Circuit
Electromagnetic Transducer
Active Vibration Isolation System
Different ways of designing an active vibration system
Two channel controller (Serrand and Elliot)
Passive system as a base (Platus)
Used in:
Semiconductor production industry
Aircraft and space applications
Optical devices
QUESTIONS???
