Insights on uniaxial compression of WS 2 inorganic fullerenes: A finite element study
- PDF / 511,001 Bytes
- 6 Pages / 584.957 x 782.986 pts Page_size
- 108 Downloads / 220 Views
David Barlam Department of Mechanical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
Ofer Tevet Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
Sidney R. Cohena) Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel (Received 4 May 2011; accepted 16 June 2011)
We report here a finite element simulation of the compression of inorganic WS2 hollow nanoparticles. The particle was modeled as a multilayered polyhedron to investigate the effect of the unique onion-like and highly faceted structure in the mechanical response. The simulation revealed the central role of the faceted structure of the WS2 nanoparticles in the mode of failure. The stress magnitude and distribution was shown to be size dependent, as predicted from previously published experimental results. Moreover, the simulation points to the influence of the layered structure on the energy release during compression loading via interlayer shear.
I. INTRODUCTION
Metal dichalcogenides are inorganic compounds with a layered two-dimensional (2D) structure, capable of forming closed-cage faceted fullerene-like nanoparticles or nanotubes.1,2 The mechanical response of MX2 (M 5 W, Mo, Nb, Hf; X 5 S, Se) nanotubes to external loads was widely studied in the uniaxial tension3,4 and compression modes.5 Recently, the radial modulus of WS2 nanotubes was investigated using an atomic force microscope indentation technique and computational simulations.5,6 The value obtained was very close to that of the interlayer shear modulus7 and points to the importance of the sliding between layers in moderating the radial modulus. Inorganic fullerenes and nanotubes are in high demand as novel solid lubricants.8 The collective response to load of these novel nanostructures is critical in such applications. The mechanism of failure in both inorganic nanotubes and the fullerene-like structures has also been investigated experimentally and theoretically.8–14 The mode of failure suggested in the case of the nanotube (NT) initiates at the innermost layer of the hollow structure. 2D molecular dynamics simulations performed on MoS2 nanotubes15 supported a delamination mechanism proposed in Ref. 8 and suggested the fracture of the innermost layer as a precursor of total failure. The density-functional tight-binding (DFTB) model used also revealed the scaling relationship a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2011.212 J. Mater. Res., Vol. 27, No. 1, Jan 14, 2012
http://journals.cambridge.org
Downloaded: 13 Mar 2015
between the critical strain at breakage of the initial layer and the nanotube diameter.8 For a sample of nanotubes with the same outer diameter but different inner diameters, fracture will first occur in the nanotube with the smallest inner diameter. This mechanism was extended to fullerene-like nano-onion structures. Previous theoretical studies also predicted delamination.11 Exceeding the theoretical critic
Data Loading...
