Free and Forced Vibrations Flashcards
What are free vibrations?
When there is no energy transferred to the surroundings.
When do force vibrations happen?
When there is an external driving force.
What is the frequency of the external driving force?
Driving frequency.
When does resonance happen?
When driving frequency = natural frequency.
What forces cause energy to be lost to surroundings?
Damping forces.
What does damping do?
Reduce the amplitude of the oscillation over time. Heavier the damping the quicker the amplitude is reduced to zero.
What does critical damping do?
Reduces the amplitude in the shortest possible time.
What is over damping?
Systems that are over-damped take longer to return to equilibrium than a critically damped system.
How is plastic deformation linked to damping?
Plastic deformation of ductile materials reduces the amplitude of oscillations in the same way as damping. As the material changes shape, it absorbs energy, so the oscillation will become smaller.
