FM 07-15 (arXiv:1506.08012)

Authors: Michele Bartuccelli, Guido Gentile, James Wright

Title: Stable dynamics in forced systems with sufficiently high/low forcing frequency
 
Abstract: We consider a class of parametrically forced Hamiltonian systems with one-and-a-half degrees of freedom and study the stability of the dynamics when the frequency of the forcing is relatively high or low. We show that, provided the frequency of the forcing is sufficiently high, KAM theorem may be applied even when the forcing amplitude is far away from the perturbation regime. A similar result is obtained for sufficiently low frequency forcing, but in that case we need the amplitude of the forcing to be not too large; however we are still able to consider amplitudes of the forcing which are outside of the perturbation regime. Our results are illustrated by means of numerical simulations for the system of a forced cubic oscillator. In addition, we find numerically that the dynamics are stable even when the forcing amplitude is very large (beyond the range of validity of the analytical results), provided the frequency of the forcing is taken correspondingly low.

Keywords: Nonlinear oscillators; high driving frequency; low driving frequency; perturbation theory; KAM theorem; averaging.

Michele V. Bartuccelli
Department of Mathematics
University of Surrey
Guildford, GU2 7HX, UK
e-mail: gentile@mat.uniroma3.it

Guido Gentile
Dipartimento di Matematica e Fisica
Università Roma Tre
Largo San Leonardo Murialdo 1 - 00146 Roma - Italy
e-mail: gentile@mat.uniroma3.it

James A. Wright
Department of Mathematics
University of Surrey
Guildford, GU2 7HX, UK
e-mail: j.wright@surrey.ac.uk