R. Khasminskii et N. Moshchuk, MOMENT LYAPUNOV EXPONENT AND STABILITY INDEX FOR LINEAR CONSERVATIVE SYSTEM WITH SMALL RANDOM PERTURBATION, SIAM journal on applied mathematics, 58(1), 1998, pp. 245-256
Asymptotic expansion series for the moment Lyapunov exponent and stabi
lity index are constructed and justified for the two-dimensional linea
r stochastic system close to a harmonic oscillator. As an example, a o
ne-degree-of-freedom mechanical system parametrically excited in stiff
ness and damping is considered and several terms of the expansion are
obtained.