شاهرخ حسینی هاشمی

[ 1 ] - بررسی تاثیر همزمان مدول‌های کششی- فشاری و برشی پیوندهای واندروالسی بر روی ارتعاشات نانوریبون‌های گرافنی دولایه با شرایط مرزی مختلف

در این پژوهش، اثرات شرایط مرزی مختلف بر ارتعاشات آزاد نانوریبون‌های دو لایه برای حالتی که هر دو نوع اثرات کششی- فشاری و برشی پیوندهای واندروالسی بصورت همزمان در نظر گرفته شده باشند، بررسی شده است. به منظور مدل‌سازی نانوریبون دو لایه، از تئوری تیرهای ساندویچی استفاده شده است. در مراجع موجود تنها یکی از دو اثر کششی- فشاری و یا برشی پیوندهای واندروالسی مورد بررسی قرار گرفته است. در این پژوهش پیوند...

[ 2 ] - مقایسه تاثیر پارامتر غیر محلی بر ارتعاشات نانوتیوب ها، بر اساس حل دقیق نظریه های اویلر، تیموشنکو و پوسته ی سندرز مرتبه اول

ارتعاشات نانوتیوبها در مقالات بسیاری توسط نظریههای مختلفی مورد بررسی قرار گرفته است که حاکی از تفاوتهای مشهودی در نتایج است. بنابراین در این مقاله، رفتار ارتعاشی نانوتیوبها بر اساس دو نظریه تیرها، نظریههای اویلر و تیموشنکو، و همچنین نظریه پوسته استوانه ای مرتبه اول برشی مورد بررسی قرار گرفته است. به منظور اعمال اثر مقیاس نیز از نظریه الاستیسیته غیر محلی استفاده شده است. معادلات بدست آمده برای...

[ 3 ] - Low Velocity Impact on Relatively Thick Rectangular Plate under In-plane Loads Resting on Pasternak Elastic Foundation

This study deals with the elastic-plastic impact on moderately thick rectangular plate subjected to uniform in-plane compressive loads resting on the Pasternak elastic foundation. The proposed rectangular plates have two opposite edges simply-supported, while all possible combinations of free, simply-supported and clamped boundary conditions are applied to the other two edges. The dimensionless...

[ 4 ] - Surface Effects on Free Vibration Analysis of Nanobeams Using Nonlocal Elasticity: A Comparison Between Euler-Bernoulli and Timoshenko

In this paper, surface effects including surface elasticity, surface stress and surface density, on the free vibration analysis of Euler-Bernoulli and Timoshenko nanobeams are considered using nonlocal elasticity theory. To this end, the balance conditions between nanobeam bulk and its surfaces are considered to be satisfied assuming a linear variation for the component of the normal stress thr...

[ 5 ] - تحلیل ارتعاشات آزاد ورق های بیضوی ساخته شده از مواد FGM

This paper deals with a free vibration analysis of functionally graded elliptical plates with different classical boundary conditions on the basis of polynomial-Ritz method and classical plate theory. The proposed admissible function is capable to obtain accurate natural frequencies of various classical boundary conditions namely, clamped, free and simply supported edges. The mechanical propert...

[ 6 ] - Vibration analysis of a Timoshenko non-uniform nanobeam based on nonlocal theory: An analytical solution

In this article free vibration of a Timoshenko nanobeam with variable cross-section is investigated using nonlocal elasticity theory within the scope of continuum mechanics. Small scale effects are modelled after Eringen’s nonlocal elasticity theory while the non-uniformity is presented by exponentially varying width through the beam length with constant thickness. Analytical solution is achiev...

[ 7 ] - Vibration analysis of a Timoshenko non-uniform nanobeam based on nonlocal theory: An analytical solution

In this article free vibration of a Timoshenko nanobeam with variable cross-section is investigated using nonlocal elasticity theory within the scope of continuum mechanics. Small scale effects are modelled after Eringen’s nonlocal elasticity theory while the non-uniformity is presented by exponentially varying width through the beam length with constant thickness. Analytical solution is achiev...

[ 8 ] - Free Vibration Analysis of Nonuniform Microbeams Based on Modified Couple Stress Theory: an Analytical Solution

In this study, analytical solution is presented to calculate the free vibration frequencies of nonuniform microbeams. Scale effects are modelled using modified couple stress theory and the microbeam is assumed to be thin while Poisson's ratio effects are also taken into account. Nonuniformity is presented by exponentially varying width among the microbeam while the thickness remains constant. R...

[ 9 ] - Free Vibration Analysis of Functionally Graded Materials Non-uniform Beams

In this article, nonuniformity effects on free vibration analysis of functionally graded beams is discussed. variation in material properties is modeled after Powerlaw and exponential models and the non-uniformity is assumed to be exponentially varying in the width along the beams with constant thickness. Analytical solution is achieved for free vibration with simply supported conditions. It is...

[ 10 ] - Analytical Solution for Free Vibration of a Variable Cross-Section Nonlocal Nanobeam

In this article, small scale effects on free vibration analysis of non-uniform nanobeams is discussed. Small scale effects are modelled after Eringen’s nonlocal elasticity theory while the non-uniformity is presented by exponentially varying width among the beams length with constant thickness. Analytical solution is achieved for free vibration with different boundary conditions. It is shown th...

[ 11 ] - Bifurcation and Chaos in Size-Dependent NEMS Considering Surface Energy Effect and Intermolecular Interactions

The impetus of this study is to investigate the chaotic behavior of a size-dependent nano-beam with double-sided electrostatic actuation, incorporating surface energy effect and intermolecular interactions. The geometrically nonlinear beam model is based on Euler-Bernoulli beam assumption. The influence of the small-scale and the surface energy effect are modeled by implementing the consistent ...