Damping & Plastic Deformation
- Damping an oscillator affects its amplitude of oscillation:
- When damping is increased the amplitude decreased
- damping and amplitude are inversely proportional to each other
As damping is increased, resonance peak lowers, the curve broadens and moves slightly to the left
- A Ductile material can be stretched for a long time before it snaps
- We can say it undergoes a large amount of plastic deformation before it is permanently deformed
- Examples of ductile materials include:
- Most metals (particularly copper, gold and silver)
- Non-metals are generally not ductile
Brittle and ductile materials on a stress-strain graph. These are the same on a force-extension graph too
- The amplitude of oscillations can be reduced due to the plastic deformation of a ductile material
- This happens because energy from the oscillations is used to deform the material
- The kinetic energy of the oscillator is reduced and transferred into the deformation of the material
- A climbing rope is different from a rescue rope or a bungee cord:
- A climbing rope is designed to extend when loaded suddenly
- The rope stretches to reduce the amplitude of the oscillation when a climber falls onto it
- It provides critical damping by immediately stopping the climber from bouncing
A climber uses a dynamic rope that stretches when she falls onto it. This reduces the amplitude of her oscillation and the force she experiences reducing injury.
