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Mechanical vibrations
1. Mechanical vibrations
MECHANICALVIBRATIONS
Free vibration damped system
PRESNED TO :
Eng. Mohamed Shahata
2. PRESNTED BY
1- Hossam Hamdy3. Contents
CONTENTS1- Introduction
2- Definition of damping
3- Types of damping
4- Example
5- Application
6- Review
7- Measurement
8- Summary
9- References
4.
Every object, every particle and every systemoscillates in its own natural frequency or set of
frequencies.
what does natural Frequency mean…??
5. Damped Oscillations
DAMPED OSCILLATIONSAmplitude goes on decreasing with time.
6. Types of Damping Oscillations
TYPES OF DAMPINGOSCILLATIONS
Over-damped
Critically damped
Under damped
7.
TYPES OF DAMPING OSCILLATIONSStringed instruments “Under-damped”
Gun “Critical”
Toilet flush button “Over-damped”
8. Types of damping
TYPES OF DAMPING1- Material damping
(internal friction, mechanical hysteresis)
2- Friction at joints
3- Added layers of materials with high loss factors
(e.g. viscoelastic materials)
4- Hydraulic dampers (shock absorbers, hydromounts)
5- Air/oil pumping: squeeze-film damping
9. Types of damping
TYPES OF DAMPING1- Material damping
(internal friction, mechanical hysteresis)
2- Friction at joints
3- Added layers of materials with high loss factors
(e.g. viscoelastic materials)
4- Hydraulic dampers (shock absorbers, hydromounts)
5- Air/oil pumping: squeeze-film damping
10. Hydraulic dampers
HYDRAULIC DAMPERSUsed for bridges, buildings and cars to absorb the impact from the
bumps and earthquakes.
In Bridges
In Buildings
11.
Hydro-mounts in carShock absorber in car
12. Review of Damping Mechanisms
REVIEW OF DAMPINGMECHANISMS
x
The equation of motion is
mx cx kx 0
inertia force
damping force
stiffness force
13. Free vibration effect of damping
FREE VIBRATION EFFECT OFDAMPING
The under-damped displacement of the mass is given by
14.
Free vibration effect of damping15.
16. References
REFERENCEShttp://www.differencebetween.net/technology/difference-between-damped-andundamped-oscillations/#ixzz6809aeCmN
http://www.differencebetween.net/technology/difference-between-damped-andundamped-oscillations/#ixzz680BORYIN
http://www.differencebetween.net/technology/difference-between-damped-andundamped-oscillations/#ixzz680GFHgHg
https://www.youtube.com/watch?v=ZelrMxj7X0&list=PLdGICjKjvr_PxHrwtfTlleXz6WlybfzQt&index=7
https://www.quora.com
https://www.physicsforums.com
17.
Thanksfor your time