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TECHNIQUES FOR EVALUATING STRESSES AND STRAINS IN MICRO-SYSTEMS

Jacek Jackiewicz 

University of Technology & Agriculture, Department of Mechanical Engineering, Prof. S. Kaliskiego 7, Bydgoszcz 85-791, Poland

Abstract

Well-known finite element method is an excellent tool for the assessment of the integrity of micro packages because it is often impossible or very difficult to measure temperature distributions and plastic zones on such tiny components. However this method employs mostly the classical continuum mechanics, which is based on the fundamental idea that laws of motion and the axioms of constitution are valid for every element of the body no matter how small it may be. When the spatial discretisation grid is refined, the finite element approximation becomes more accurate in the sense that the displacement gradients become stronger but this assumption is not longer applicable as the characteristic dimension of a structure becomes comparable to or smaller than the periodic atomic scale domain. It is accepted that many effects on the continuum start developing at the atomic level. Therefore, a computational mechanics method is necessary that can couple different in kind scales, one scale in which the boundary conditions are applied and the other in which atoms reside. The results of atomistic calculations depend upon two factors: the interatomic potential used to model the interactions between the atoms in the inner region and the boundary conditions used to model the effect of outer region. The aim of investigations is to provide a non-local description of nano-materials versus discrete formulations based on mechanics of nano-structures. These studies on the non-local description of nano-materials are motivated by homogenisation of the atomic theory of Bravais lattices, aimed at a better description of phenomena taking place in crystals on a scale comparable to the range of interatomic forces. The evaluation of stresses in micro-systems, which lead to damage is also the centre of attention.

 

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Related papers

Presentation: poster at E-MRS Fall Meeting 2004, Symposium H, by Jacek Jackiewicz
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-29 14:03
Revised:   2009-06-08 12:55