School of Mechanical Engineering Seminar
Monday, November 3, 2014 at 15:00
 The Wolfson Software Engineering Building, Room 104

Discrete and continuum models  to determine the elastic and dynamical properties of materials and structures at micro- and nanoscale

Dr. Igor Berisnkii

Institute for Problems in Mechanical Engineering of Russian Academy of Sciences,

St. Petersburg Polytechnic University (St. Petersburg, Russia)

Solid mechanics concept is widely accepted to model mechanical properties of materials and systems. However, at micro- and nanoscale the microstructure plays an essential role and can not be neglected. At these scales the material can be represented as a discrete medium. This approach gives an opportunity to easily consider the discontinuous effects and determine the properties of the effective elastic media using the knowledge of microparameters such as geometry of crystal lattice and interatomic interaction. Moreover, this approach is also very successful at macroscale to simulate the dynamical processes in cases of material continuality loss.

However, continuum mechanics still is a most convenient instrument for some new tasks of nanomechanics of coupled quasi-stationary magnetic and electric fields. A nano-resonator based on graphene layer suspended over a groove in silicon oxide is considered as an electromechanical system. An electromagnetic field with a high frequency applied to such system generates the mechanical oscillations. As this system is sensitive to change of mass of the oscillating film, it can be used as an ultraprecise mass sensor allowing weighing the single particles. Change of the spectral properties due to a small mass addition is hard to determine experimentally. Due to this, different approaches to improve sensitivity of the nanoresonator are proposed.

A short review of discrete and continuum models at micro- and nanolevel will be presented. Different applications of these models including the simulation of carbon nanostructures and dynamical fracture of materials will be discussed.