[ \mathbfM\ddot\mathbfu + \mathbfC\dot\mathbfu + \mathbfK\mathbfu = q_\infty \left( \mathbfA_0 \mathbfu + \mathbfA_1 \dot\mathbfu + \int_0^t \mathbfG(t-\tau)\dot\mathbfu(\tau) d\tau \right) ]
Divergence occurs when the smallest eigenvalue (\lambda_\min) of (\mathbfK^-1 \mathbfA 0) satisfies (q \infty, \textdiv = 1 / \lambda_\min). Physically, aerodynamic moments overcome structural stiffness. Assume harmonic motion (\mathbfu = \hat\mathbfu e^i\omega t) and use frequency-domain aerodynamics (\mathbfQ(i\omega)): theoretical and computational aeroelasticity pdf
typically uses a loose staggering with sub-iterations: \textdiv = 1 / \lambda_\min). Physically