چكيده به لاتين
In this thesis, the vibration behavior and wave propagation of Viscoelastic Functionally Graded Porous (VFGP) nanobeams in presence of surface effects have been explored in the frame work of two-phase local/nonlocal elasticity. To this end, in chapter one, a brief introduction is presented about nanotechnology and its applications. Second chapter is produced to express the previous literatures and its results. Also, the reason of paradoxes in nonlocal elasticity are explained. Moreover, two-phase elasticity is introduced as a paradox free form of nonlocal size dependent theory. Chapter three contains the problem formulation of VFGP nanobeams based on surface elasticity, Euler-Bernoulli as well as Timoshenko beam theories and two-phase elasticity. Accordingly, the governing equations are derived through the Hamiltons principle. Also, to obtain the vibration characteristics of nanobeams, exact solution and Generalized Differential Quadrature Method (GDQM) as numerical solution, respectively, for Euler-Bernoulli and Timoshenko nanobeams have been presented. Furthermore, harmonic wave propagation of Timoshenko nanobeams upon the both form of two-phase elasticity is performed. In fourth chapter, to examine the validity and credibility of problem formulation and results, several comparative study are performed. Lastly, several benchmark results are produced to probe into the influences of different parameters on vibration behavior and wave propagation of VFGP nanobeams.
