RESONANCE & DAMPING

SPH 3U

Resonance & Damping Think of life on the swings:

How do you go faster?

How do you slow down?

Resonance & Damping Swings are examples of resonance and

damping

Damping: a reduction in the amplitude of a wave as a result of energy absorption or destructive interference

The amplitude is minimized

Resonance & Damping All things have a resonant frequency –

this is the ‘natural’ frequency

Resonance occurs when the frequency of the waves affecting the object are equal to the resonant frequency

The amplitude is increased

Resonance & Damping

Mythbusters (breaking glass)

Waves & Structures Mechanical Resonance: When energy

transfers from one source to another with the same natural resonance

Aeroelastic Flutter: When more energy is added by vibrations then can be lost by natural damping

Often caused by wind interacting with the aerodynamics of an object

Waves & Structures

Tacoma Narrows Bridge

Waves & Structures Structures are susceptible to wind and

earthquakes

Narrow streets increase wind speed

Wind can cause buildings to sway up to 1 m; earthquakes can cause buildings to exceed this

Waves & Structures Before WWII, tall buildings were

constructed with thick concrete walls, with steel bars

The concrete resisted compression, but was not flexible

The steel bars added some flexibility

Waves & Structures After WWII, tall

buildings were constructed using girders these are better able to withstand waves

The walls were not for support, but merely weather-proofing

Waves & Structures Earthquake Dampers

Taipei Mass Damper

Discovery Taipei 101 (3/5)