1. VIBRATION
ISOLATION

2. CONTENTS
VIBRATION ISOLATION :
 WHY ?
 HOW TO MODEL THE PROBLEM ?
 WHAT IS RESONANCE ?
 WHAT TO USE ?
 HOW TO CHOOSE A SPRING ?

3. WHY ?
VIBRATIONS CAN BE A PROBLEM FOR :
-THE MACHINE ITSELF
-THE ENVIRONMENT
TO MINIMIZE THE PROBLEM OF VIBRATIONS :
DESIGN OF A VIBRATION ISOLATION SYSTEM

4. HOW TO MODEL THE PROBLEM ?
ACTIVE ISOLATION :
F FT
OR
PASSIVE ISOLATION :
X

5. WHAT IS RESONANCE ?
RESONANCE : tendency of a system to
oscillate with larger amplitude at some
frequencies than at others.
RESONANT FREQUENCIES

6. WHAT TO USE ?
dampers
spring
boxes
aircushions
Every isolation system canbemodeled by a spring and a damper.
Here, wewillconsideronly the spring constant.

7. HOW TO CHOOSE A SPRING ?
COMPARISON BETWEEN :
- F : FREQUENCY OF THE STRUCTURE
- FO : RESONANT FREQUENCY OF THE
SPRING
IF F > FO : AMPLIFICATION OF
THE VIBRATIONS
IF F = FO : RESONANCE
IF F > FO : ABSORPTION OF
VIBRATIONS
IF F > 4 FO : T < 0,1

8. CONCLUSION
TO DESIGN A VIBRATION ISOLATION SYSTEM :
DETERMINATION OF THE FREQUENCY F OF THE MACHINE
RESONANT FREQUENCY OF THE SPRING FO = F/5
STIFFNESS K OF THE SPRING : FO =
M = mass of the machine