الفهرس 
Chapter (1) : IntroductionOnly 14 pages are availabe for public view
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Abstract
Functionally graded materials (FGMs) were introduced in the mid-1980s as ultra-high temperature-resistant materials for aerospace structures. These materials have been used in many applications such as machine elements, electrical devices,energy transformation, biomedical engineering, Micro/Nano electromechanical systems (MEMS/NEMS), etc. During the manufacture process of FGMs (i.e.; powder metallurgy, vapor deposition, self-propagation, centrifugal casting, and magnetic separation), some pores are formed within the microstructures of such materials. The formation of porosity may lead to variation of mechanical properties and hence, affects the overall mechanical behavior and performance of these FG structures. This work presents an effort to understand static bending, buckling, and dynamics of porous and nonporous functionally graded nano-sized beams. Static and dynamic properties of porous macro-sized beams are first investigated in order to help understand the behavior of the beams in the nano-size regime.The Euler-Bernoulli beam model is assumed to describe the kinematic relations and the Hookean elastic constitutive equations are proposed through analysis. To account for small size effects, the nonlocal differential elasticity model of Eringen is employed and the nanobeam equations of motion are modified accordingly. A finite element model is developed to solve the problem using MATLAB. Numerical results are presented to show the effects of porosity on the statics and dynamics of functionally-graded macro and nano sized beams. Porosity is taken into consideration by using two porosity models. The first model describes properties in explicit form as linear functions of the porosity parameter. The second model is a proposed one in which porosity and Young’s modulus are presented in an implicit form where the density is a function of the porosity parameter, and Young’s modulus is a function of the ratio of mass with porosity to the mass without porosity.