NONLOCAL PROPERTIES OF INHOMOGENEOUS STRUCTURES BY LINKING APPROACH OF GENERALIZED CONTINUUM TO ATOMISTIC MODEL

Nonlocal elastic constants associated with strain gradient terms in th e Cosserat theory are linked to atomic-level properties, in particular to coefficients that arise in lattice dynamics equations when atomic displacements are expressed in terms of a continuous displacement fiel d. Therefore, the nonlocal elastic constants, including the ordinary f ourth-order ones, are expressed in terms of only both the atomic posit ions in a relaxed configuration and the force constants which are the second derivative of the employed interatomic potential with respect t o an atom position. Molecular statics and molecular dynamics simulatio ns of stable (or meta-stable) surface and grain boundary structures ar e performed using a Finnis-Sinclair-type many-body potential. Then, th e nonlocal properties are discussed, being compared with homogeneous b ulk properties to identify the characteristic length over which nonloc al effects associated with the inhomogeneous structures are significan t. (C) 1997 Published by Elsevier Science Ltd.