Nonlinear Dynamics and Bifurcation Behavior of a 2-DOF Spring Resonator with End Stopper for Energy HarvestingA. El Aroudi, E. Blokhina, D. O’Connell, B. Fu, R. Frizzell, O. Feely and E. AlarconMATEC Web of Conferences, 16 (2014) 08006DOI: https://doi.org/10.1051/matecconf/20141608006