Dislocation motion and instability

Yichao Zhu       Stephen J. Chapman       Amit Acharya

(to appear in Journal of the Mechanics and Physics of Solids)

The Peach-Koehler expression for the stress generated by a single (non-planar)
curvilinear dislocation is evaluated to calculate the dislocation self stress. This is
combined with a law of motion to give the self-induced motion of a general dislocation
curve. A stability analysis of a rectilinear, uniformly translating dislocation is then
performed. The dislocation is found to be susceptible to a helical instability, with
the maximum growth rate occurring when the dislocation is almost, but not exactly,
pure screw. The non-linear evolution of the instability is determined numerically, and
implications for slip band formation and non-Schmid behaviour in yielding discussed.