[CCoE Notice] Maters Thesis Defense Announcement

[Khator, Suresh]

CURVATURE DEPENDENT SURFACE ENERGY AND IMPLICATIONS FOR NANOSTRUCTURES
by
Prakash Chhapadia

Date: 23rd November, 2010            Time: 11:00 AM        Location: W232 Engineering Bldg II

Committee Members: Dr. Pradeep Sharma. Dr. Yashashree Kulkarni, Dr. Gemunu Gunaratne

Abstract

At small length scales, several size-effects in both physical phenomena and properties can be rationalized by invoking the concept of surface energy. Conventional theoretical frameworks of surface energy, in both the mechanics and physics community, assume curvature independence. In this work we adopt a simplified and linearized version of a theory proposed by Steigmann-Ogden to capture curvature-dependence of surface energy. Connecting the theory to atomistic calculations and the solution to an illustrative paradigmatical problem of a bent cantilever beam, we catalog the influence of curvature dependence of surface energy on the effective elastic modulus of nanostructures.
The observation in atomistic calculations that the elastic modulus of bent nanostructures is dramatically different than under tension--sometimes softer, sometimes stiffer--has been a source of puzzlement in the scientific community. We show that the corrected surface mechanics framework provides a resolution to this issue. Finally, we propose an unambiguous definition of the thickness of a crystalline surface.

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