Nonlinear forced vibrations of sandwich smart nanobeams with two-phase piezo-magnetic face sheets Seyed Sajad Mirjavadi, Masoud Forsat, Mohammad Nikookar, Mohammad Reza Barati and AMS Hamouda Eur. Phys. J. Plus, 134 10 (2019) 508 Published online: 14 October 2019 DOI: 10.1140/epjp/i2019-12806-8