Tuning a driven oscillator.
Why can a small repeated force make a large motion?
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Why can a small repeated force make a large motion?
Fit the mass, springs and damper before driving.
A periodic driver can add energy at the right part of each oscillation. The steady response depends on frequency, mass, spring stiffness and damping. Near the natural frequency, the damping controls the response and the displacement lags the force by about a quarter cycle. This rig stops the linear demonstration when its predicted motion exceeds the available travel.
Linear steady-state driven mass–spring–damper. Stiffness is the combined value of the two springs. Allowed travel 70 mm: larger linear predictions are outside the operating domain of this rig and are not silently clipped. Startup transients, friction and impacts omitted. Motion slowed by 0.4.
Reach 35–70 mm of steady response without hitting the travel stops.
Compare driven amplitude and phase near resonance.