We study soliton stability under the action of strong external perturbations. Limits on the weak perturbation approach are established with the help of average Lagrangian methods and full simulations. We found that for the same relative perturbation, larger amplitude solitons develop instability earlier than weaker amplitude solitons.
Physical review. E, Statistical, nonlinear, and soft matter physics. Vol. 67, no. 4 (Apr. 2003), 047601, 4 p.