beenchang's blog

The velocity and instability of crack motion in 2D hexagonal lattice of graphene under pure opening loads
are investigated by atomistic molecular dynamics simulations. The brittle crack along zigzag direction
in a strip can propagate supersonically at even 8.82 km/s under uniform normal loading of edge
displacements. Crack moving straightly at low speeds produces atomically smooth edges, while kinking
occur beyond a critical speed around 8.20 km/s equivalent to 65% of Rayleigh-wave speed in graphene,

Nanoscale fracture of graphene under coupled in-plane opening and shear
mechanical loading is investigated by extensive molecular dynamics
simulations. Under opening-dominant loading, zigzag edge cracks grow
self-similarly. Otherwise, complex stresses concentrated around
crack-tip can manipulate the direction of crack initiation changing by
30° (or multiples of 30°). Toughness determined by obtained critical
stress intensity factors 2.63–3.38 nN Å−3/2
demonstrates that graphene is intrinsically brittle opposite to its
exceptional high strength at room temperature. Torn zigzag edges are
more energetically and kinetically favorable. Cracking of graphene has