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MM: Fachverband Metall- und Materialphysik

MM 36: Topical Session (Symposium MM): Fundamentals of Fracture

MM 36.2: Vortrag

Mittwoch, 14. März 2018, 12:00–12:15, TC 006

Temperature Dependent Fracture Toughness of Defected Graphene — •Samaneh Nasiri, Debagyan Kalita, and Michael Zaiser — Friedrich-Alexander Universität Erlangen-Nürnberg, Department of Materials Science, Institute for Materials Simulation WW8 and Cluster of Excellence EAM/FUMIN Dr.-Mack-Strasse 77, 90762 Fürth, Germany

It is well known that sp* bonded carbon nanoparticles, in particular Graphene and Carbon Nanotubes, possess excellent mechanical properties in terms of in-plane elastic modulus and rupture strength. It is therefore an obvious question whether these properties can be influenced by defects. The present work investigates crack nucleation and crack propagation in defected graphene sheets over a wide range of temperatures. We consider the fracture behavior of graphene containing localized defects (vacancies) and/or extended defects (cracks) using atomistic (molecular dynamics) simulation. Fracture strength is shown to obey a Bazant-type size effect law where the internal length (process zone size) is of the order of the atomic spacing. The fracture toughness is also calculated in terms of the critical stress intensity factor for various temperatures from zero to as high as 3200 K. Results indicate a transition towards a different failure behavior and crack propagation pattern at temperatures above 2000K which may be interpreted in terms of a sub-nanometer scale brittle-to-ductile transition.

Keywords: graphene, fracture, temperature, crack, toughness, brittle-ductile transition