M. Shaat's blog

In the present paper, for linear elastic materials, effects of couple stresses on micro/nanosolids are physically discussed and mathematically represented in the context of the classical, the modified and the consistent couple–stress theories. Then, an evaluation is provided showing the validity and the limit of applicability of each one of these theories. At first, the possible couple stress effects on mechanics of particles and on continuum mechanics are represented.

This paper is now in Press and available on line at the Intenational Journal of Mechanical Sciences.

This paper is now in press at Finite Element Analysis and Design International Journal.

Many researchers have studied the effect of surface energy on the
elastic behavior of nano-structural elements based on Gurtin and Murdoch surface
model. Many of them, however, assumed that the surface energy depends only on
the 2D symmetric infinitesimal surface strains and neglects the second-order
products of surface strains/displacement gradients. Moreover, there are some
researchers assumed that the surface energy is independent on infinitesimal
rotation tensor and neglected all rotation

Extremely small size of nano-structures such as beams, sheets and
plates, which are commonly used as components in Nanoelectromechanical Systems
(NEMS), presents a significant challenge to the researchers of nano-mechanics.
Several studies have been developed on the mechanical behavior of nano-sized
bars, tubes, sheets and plates. The results of these studies show that the
elastic modulii of such nano-structural elements depend on their size.
Unfortunately, classical elasticity lacks an intrinsic length scale and thus