A shallow arch or buckled beam has two stable states separated by an energy barrier. Applied force causes catastrophic snap-through — the hallmark of bistable elastic structures.
Energy landscape V(x) = k·(x²−h₀²)²/(4h₀²) − F·x. Two minima at x=±h₀ when |F| less than critical. Snap-through: barrier disappears as F increases — saddle-node bifurcation. Dynamics: mẍ + γẋ = −dV/dx.