Vibration behaviour of a bio-composite sandwich with auxetic core Khawla Essassi, Jean-Luc Rebiere, Abderrahim El Mahi, Mahamane Toure, Mohamed amine Ben Souf, Anas Bouguecha and Mohamed Haddar MATEC Web Conf., 283 (2019) 09004 Published online: 28 June 2019 DOI: 10.1051/matecconf/201928309004