title: Modelling the Size Effects on the Mechanical Properties of Micro/Nano Structures.
abstract: Experiments on micro- and nano-mechanical systems (M/NEMS) have shown that their behavior under bending loads departs in many cases from the classical predictions using Euler-Bernoulli theory and Hooke's law. This anomalous response has usually been seen as a dependence of the material properties on the size of the structure, in particular thickness. A theoretical model that allows for quantitative understanding and prediction of this size effect is important for the design of M/NEMS. In this paper, we summarize and analyze the five theories that can be found in the literature: Grain Boundary Theory (GBT), Surface Stress Theory (SST), Residual Stress Theory (RST), Couple Stress Theory (CST) and Surface Elasticity Theory (SET). By comparing these theories with experimental data we propose a simplified model combination of CST and SET that properly fits all considered cases, therefore delivering a simple (two parameters) model that can be used to predict the mechanical properties at the nanoscale.
authors.affiliation: Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. am.abazari@gmail.com.|Advanced NEMS Group, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland. am.abazari@gmail.com.
authors.forename: Amir Musa
authors.initials: AM
authors.lastname: Abazari
authors.affiliation: Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. mosafavi@cc.iut.ac.ir.
authors.forename: Seyed Mohsen
authors.initials: SM
authors.lastname: Safavi
authors.affiliation: Department of Mechanical Engineering, Urmia University, Urmia 57561-51818, Iran. g.rezazadeh@urmia.ac.ir.
authors.forename: Ghader
authors.initials: G
authors.lastname: Rezazadeh
authors.affiliation: Advanced NEMS Group, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland. lgv@lgvillanueva.info.
authors.forename: Luis Guillermo
authors.initials: LG
authors.lastname: Villanueva
mesh_terms: D004548:Elasticity; D055616:Microtechnology; D008962:Models, Theoretical; D049329:Nanostructures; D036103:Nanotechnology; D010316:Particle Size; D013314:Stress, Mechanical; D013499:Surface Properties
keywords: Young’s modulus; couple stress; grain boundary; length scale parameter; residual stress; size effect; surface elasticity; surface stress