Bending of nanoscale structures: Inconsistency between atomistic simulation and strain gradient elasticity solution

Strain gradient effect of micro- and nanoscale structures in plasticity is well known. Elastic strain gradient effect has also been reported, but so far only theoretical work about this issue could be found. No confirmatory data obtained from experiments and atomistic simulation has been published. In the present paper, molecular statics simulation of Cu and Si nanoplates bending was carried out and compared to a strain gradient elasticity solution to ascertain whether there is also any strain gradient effect in elastic range, and its significance if presence. It is shown that there exists a noticeable inconsistency between atomistic simulation and theoretical prediction. In contrary to hardening effect predicted by the strain gradient elasticity, the atomistic simulation results reveal a significant softening effect in diamond silicon nanoplate bending when the thickness is less than 10 nm. Although a hardening effect is exhibited in the atomistic simulation of FCC copper nanoplate bending, it is negligible. We regard this paper as an attempt to draw more attention and discussion about this issue in the community of this area.