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International Journal for Multiscale Computational Engineering

Impact factor: 1.103

ISSN Print: 1543-1649
ISSN Online: 1940-4352

International Journal for Multiscale Computational Engineering

DOI: 110.1615/IntJMultCompEng.2015013568
pages 413-442

A CONTINUUM MECHANICAL SURROGATE MODEL FOR ATOMIC BEAM STRUCTURES

Marcus G. Schmidt
AICES Graduate School, RWTH Aachen University, Aachen, Germany
Ahmed E. Ismail
AICES Graduate School, RWTH Aachen University, Aachen, Germany; Aachener Verfahrenstechnik: Molecular Simulations and Transformations, Faculty of Mechanical Engineering, RWTH Aachen University, Aachen, Germany
Roger A. Sauer
AICES Graduate School, RWTH Aachen University, Aachen, Germany

ABSTRACT

Starting from a fully atomistic system, we outline a general approach to obtain an approximate continuum surrogate model incorporating specific kinematic state variables. The continuum mechanical system is furnished with a hyperelastic material model. We then adapt the procedure to slender structures with beam-like character, such as silicon nanowires or carbon nanotubes. The surrogate model can be described as a geometrically exact beam, which can be treated numerically using finite elements. Based on molecular dynamics simulations, we show how to obtain for a given atomistic beam system both a set of suitable deformed states as well as generalized stress and strain measures. Finally, we benchmark the obtained continuum model by assessing its accuracy for a beam coming into contact with an infinite Lennard-Jones wall.