Dislocation-based plasticity model by analysis of discrete dislocation dynamics

Dislocation-based plasticity model by analysis of discrete dislocation dynamics

Zheng, Yiwen (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Materials Science and Engineering)

Sietsma, J. (mentor)
van Dokkum, J.S. (mentor)
Offerman, S.E. (graduation committee)
van Dijk, N.H. (graduation committee)

Delft University of Technology

Materials Science and Engineering

2021-10-05

Plasticity accompanied by dislocation motion is the essential property of metals. A large number of crystal plasticity models have been developed to predict the mechanical response in the work hardening regime while little attention is paid to pre-yield behavior. In this work, we propose a novel model both pre-yield and post-yield from a discrete dislocation dynamics (DDD) database of 55 DDD realizations. Dislocation density and Frank-Read source height are chosen as microstructural state variables to represent the material state. Flow rule and dislocation multiplication model are in good agreement with DDD results. Discrepancies result from the onset of micro-plasticity in pre-yield. The axial stress-strain response predicted by the novel model is consistent with current DDD data. The evolution equation of source height fails in capturing the evolution in accordance with DDD data, which originates from the inaccuracy brought by indirect extraction of source shape from DDD dislocation networks. Future research recommendations include enlargement of the database, extraction of source shape in situ, and evolution equations for link-based microstructural variables.

discrete dislocation dynamics
constitutive modeling
plasticity

http://resolver.tudelft.nl/uuid:41bf2e4c-f4be-4451-80fd-c299f4d56811

2026-10-05

Student theses

master thesis

© 2021 Yiwen Zheng