This document discusses vibration isolation. It begins by explaining why vibration isolation is important, both for machines and their environments. It then discusses modeling isolation as either active or passive systems. It defines resonance as when a system oscillates with larger amplitudes at certain frequencies. It lists common isolation devices like springs, dampers, boxes, and air cushions. It concludes by providing guidelines for choosing an appropriate spring based on the machine's frequency and the desired resonant frequency of the isolation system.

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