Florin Bobaru
University of Nebraska-Lincoln, Lincoln, Nebraska, USA

We introduce a peridynamic (PD) model for Discrete Dislocation Dynamics and verify its accuracy in uniaxial tension in a single crystal and a polycrystal. The model is then used to simulate elastoplastic fracture by considering interactions between dislocations and a growing crack.

For mode I elastoplastic fracture in a single crystal, we observe that the crack path is “attracted” towards regions of high density of gliding dislocations, leading to an undulating crack paths, as observed in experiments but never replicated by continuum-level computational models before. Tests on different sample sizes show how the proximity of constraints to the crack tip can lead to plastic hardening. Ductile-to-brittle transition happens naturally in this model when the crack, under mode I displacement-controlled loading, approaches a free edge.

The new PD model can be used to investigate complicated elastoplastic fracture problems in which the interaction between dislocation motion and damage is critical. This work is in collaboration with Prof. Ziguang Chen's group at Huazhong University of Science and Technology, Wuhan, China. For details please see: https://doi.org/10.1016/j.ijplas.2022.103462