On nonlinear dynamic of a non-ideal Duffing system with fractional damping J M Balthazar, A M Tusset, V Piccirillo, A Nabarrete, G Litak and C Oliveira MATEC Web Conf., 83 (2016) 01002 Published online: 16 November 2016 DOI: 10.1051/matecconf/20168301002