Te. Buchheit et al., CAPTURING THE INFLUENCE OF SURFACE CONSTRAINTS IN SMALL AND THIN SAMPLES USING POLYCRYSTALLINE PLASTICITY THEORY, Modelling and simulation in materials science and engineering, 5(4), 1997, pp. 421-437
A rate-dependent, single-crystal plasticity model for face-centred cub
ic crystal structures has been implemented into a large strain elastic
-plastic, finite-element code to examine the mechanical influence of t
he reduced surface constraints of relatively small polycrystalline agg
regates. The implemented model simulates deformation of a polycrystal
composed of cubic grains where each grain is a single finite element.
Mechanical constraint is varied by changing (a) specimen thickness and
(b) specimen volume, relative to grain size. Numerical uniaxial tensi
le tests have been performed to a strain level of 0.01. Direct and sta
tistical examination of the model results revealed the reduced flow st
ress of grains at specimen surfaces, edges and corners. The results of
these simulations are in good agreement with previous experimental st
udies which suggest that 5-10 grains across the minimum dimension of a
structure are necessary to approximate true continuum polycrystalline
response.