Sharif Digital Repository

The utility of nano-beams in MEMs and NEMs has progressed a lot in recent years. Such systems have found wide spread use in sensors and actuators due to small size, low weight, high accuracy and low energy consumption. By a decrease in size of nano-beams, surface effect increases which makes the classical theories unable to modeling such beams. Therefore new models are required for evaluating the dynamic behavior of nano-beams. In this thesis we have attempted to develop a suitable Coarse-Grain model for analysis of such beams. At first a suitable Coarse-Grain mapping with determined Sutton-Chen potential parameters is introduced for FCC metals. In the next step, EAM is considered as... 

In this thesis, static and dynamic analysis of nano beams based on second strain gradient theory is presented. Due to their small sizes, nano electro mechanical devices (NEMS) hold tremendous promise for novel, versatile and very sensitive devices for different applications ranging from actuators, transducers and also mass, force, light and frequency detectors. Therefore accurate modeling and analysis of such devices has an important role in their design and performance improvement. Neglecting the size effect, traditional theory of elasticity can not be suitable to predict mechanical behavior of these systems and so, it should be used non-classical theories which include size dependency... 

In the following research a novel method for vibration analysis of nano-structures has been presented. This method is based on equalizing the lattice stiffness to a continuous model. In this method, an equivalent continuous system is considered for each atomic lattice and for the equivalent system a modified differential equation is presented. The governing equation of the continuous system is modified in such a way that the displacement field of the atomic lattice obtained by solving this differential equation gives similar responses to the displacement field of atomic lattice. This differential equation is derived from the Taylor expansion of the displacement field about the lattice atoms....