Physics
Bridge flutter
Wind couples bending and torsion in an illustrative bridge-section model. Compare subcritical decay with flutter above the calculated linear threshold and nonlinear amplitude limitation.
Try this
Raise wind above the computed stability boundary. Bending and torsion exchange work through aerodynamic coupling. An illustrative two-mode section, not a Tacoma reconstruction; deflection scale is exaggerated.
Equations used in the module
Equations h″ + 2ζωh h′ + ωh² h = q θ − 0.4 h³ − 0.3 h² h′ θ″ + 2ζωθ θ′ + ωθ² θ = −q h − 0.4 θ³ − 0.3 θ² θ′ q = 0.003 U²; stability from Routh–Hurwitz quartic criterion
