Concept

Aeroelasticity — where it appears

The study of forces that a structure's own motion creates in the flow around it, where load and response cannot be computed separately.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

The wind that brings its own frequency

Every other load in this subject arrives at whatever rate it happens to arrive at. Vortex shedding arrives at a rate set by the wind speed — so for any chimney, mast or cable there is always a wind speed at which the shedding matches the structure exactly, and it is a breeze rather than a storm.

dynamics · vortex shedding

The motion that feeds itself

A steady wind contains no frequency at all, and it can destroy a bridge. The force that does it is manufactured by the structure's own movement, so there is no excitation to resonate with — there is a wind speed above which the equilibrium is unstable, and below which nothing happens.

dynamics · aeroelastic instability

Named alongside it

The objects these essays reach for when they reach for this one.

Damping Critical velocity Cross wind response Flutter Galloping Lock in Negative damping Resonance Scruton number Self excitation Stability threshold Strouhal number

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