Bi-layer graphene (BLG) can be a cheaper and more stable alternative to
graphene in several applications. With its mechanical strength being almost
equivalent to graphene, BLG also brings advanced electronic and optical
properties to the table. Furthermore, entrapment of water in graphene-based
nano-channels and devices has been a recent point of interest for several
applications ranging from energy to bio-physics. Therefore, it is crucial to
study the over-all mechanical strength of such structures in order to prevent
system failures in future applications. In the present work, Molecular Dynamics
simulations have been used to study crack propagation in BLG with different
orientations between the layers. There is a major thrust in analyzing how the
angular orientation between the layers affect the horizontal and vertical crack
propagation in individual layers of graphene. The study has been extended to
BLG with confined water in interfaces. Over-all strength of graphene sheets
when in contact with water content has been determined, and prominent regional
conditions for crack initiation are pointed out. It was seen that in the
presence of water content, graphene deviated from its characteristic brittle
failure and exhibited the ductile fracture mechanism. Origin of cracks in
graphenes was located at the region where the density of water dropped near the
graphene surface, suggesting that the presence of hydroxyl groups decelerate
the crack formation and propagation in straining graphenes.Comment: 24 pages, 10 Figure