This first simulation shows crack initiation in silica. New crystal is constantly fed to the advancing crack, while cracked material is lopped off at the tail. However, at any stage the simulation involves about 34,000 atoms, with each atom having up to 40 interacting neighbors. Silicon atoms are blue and oxygen atoms are red, with shadings to brighter colors for higher kinetic energies. The strain is being increased very slowly along the vertical.
Fracture occurs by the breaking of atomic bonds.
One of the best ways to analyze the atomic effects in dynamic fracture is by simulation, understanding of which is greatly facilitated by visualization. This simulation was run on the High Performance Computing Facility Cray J916 parallel vector processor, using code developed at the Center for Nonlinear Dynamics . Images were rendered on CNLD computer systems, then recorded onto video tape and converted into animation files in the Visualization Lab. This second simulation shows stable crack propagation in silicon. When a piece of material is not stretched too much, a crack traveling through the material can be atomically sharp, leaving perfectly flat surfaces behind.