1. Associate Professor, Dept. of Mechanics and Materials, Univ. of Reggio Calabria, Via Graziella Feo di Vito, 89060 Reggio Calabria, Italy (corresponding author). E-mail: friccia@unirc.it
2. Formerly, Ph.D. Student, Dept. of Mechanics and Materials, Univ. of Reggio Calabria, Via Graziella Feo di Vito, 89060 Reggio Calabria, Italy.