### Abstract

**
Molecular dynamics simulations of crack propagation in
quasicrystals
**
In a large number of experiments it has been proven that plastic
deformation of quasicrystals can occur by a dislocation mechanism. By
use of molecular dynamics simulations we have investigated the
application of shear stress to a three-dimensional model quasicrystal
in which we had built in an edge dislocation of the Peierls-Nabarro
type. To determine suitable Burgers vectors we have calculated the
gamma surface, i.e. the misfit energy obtained by a rigid shift of two
sample halves along a glide plane. The sample was an approximant of
the Ammann-Kramer-Penrose-Tiling decorated according to Henley and
Elser (Phil. Mag. B 53 (1986), 59). It consisted of 1 504 080 atoms
interacting via Lennard-Jones-Potentials. We performed simulations in
the microcanonical ensemble at zero temperature. To detect the
dislocation line we have used several visualization methods. We have
plotted only particles with a potential energy above a threshold
leading to pictures of both the atoms in the dislocation core and in
the stacking fault in the wake of the dislocation. To distinguish
among them we have used image processing algorithms. The
displacement field of the configuration has also been computed. We
have observed climb and glide motion of the dislocation. The climb
motion is caused mainly by boundary effects due to the sample
geometry. The glide motion shows kinks due to structural elements that
act as pinning centers. The width of the kinks is about 20
quasilattice constants.