Study on buckling behaviours of single- and multi-layered graphene sheets by molecular dynamics simulations

Speaker: Yang Xiang

Affiliation: University of Western Sydney

Time: Monday 25/08/2014 from 14:00 to 15:00

Venue: Access Grid UWS. Presented from Penrith (Y239), accessible from Parramatta (EB.1.32) and Campbelltown (26.1.50).

Abstract: We investigated the buckling behaviours of single- and multi-layered graphene sheets subjected to compressive inplane force in thermal environments by using molecular dynamics simulations. The graphene sheets may have either armchair or zigzag chirality and are either simply supported or clamped at the four edges. As reported previously by other researchers, we also observed that ripples are formed in the graphene sheets due to the effect of thermal fluctuations even before the compressive force is applied. The ripples are important for the graphene sheets to resist the compressive force before buckling occurs. We observed that the maximum amplitude of ripples may be reduced as the compressive force increases. The buckling mode of the graphene sheet may show local or global mode shape features.All buckling modes of the graphene sheets in this study are very different from the global (1,1) mode of an uniaxially loaded simply support or clamped square plate as predicted by the continuum mechanics models. Both the buckling force and buckling mode are size, support condition andlayer-number dependent. Therefore, the continuum mechanics models may not be valid in predicting the buckling force of single- and multi-layeredgraphene sheets subjected to compressive force. The clamped graphene sheet scan take substantial additional compressive force after the initial buckling takes place and before the maximum energy state of the graphene system is reached. The zigzag graphene sheets have a larger buckling force than their armchair counterparts. Raising the environmental temperature may either increase or decrease the buckling force of the graphene sheets,depending on the support conditions and the chirality of the graphene sheets.

Biography: Yang Xiangis currently a professor in civil engineering in the School of Computing,Engineering and Mathematics at University of Western Sydney. His researchexpertise is in computational mechanics and engineering materials. He iscurrently the Chair of the Stability Committee of ASCE EngineeringMechanics Division, an Associate Editor for International Journal ofDynamics and Control and an editorial board member for InternationalJournal of Structural Stability and Dynamics and The Journal of StrainAnalysis for Engineering Design.