Seminar

An overview of recent progresses on the theory of dislocation density fields kinematics

Speaker

Mr. Alireza Kalaei

MPhil candidate in the Mechanical Engineering Dept.

Date & Time

Friday, 30 April 2021

7:00 am

Venue

Via Zoom

Abstract:

There are different types of crystal defects e.g., point, line, and planar defects in crystal structures which always affect various properties of metals. One of the most important defects which have a significant role in the plastic deformation of metals is dislocations. The motion and interaction of these line defects are one of the considerable and the most important mechanism of plastic deformation in metals.  Thus, the Kinematics and Dynamics modeling of dislocations motion grabbed attention during recent decades, magnificently. Dislocations can be considered and simulated based on various scales or sight e.g., atomistic, discrete, and density-based. The main drawback of atomistic and discrete consideration of dislocations is the tremendous amount of required computation leading to the availability of these two scales just for a very short period and small systems, while on the latter one, the most extensive sight among the sights, it would be feasible to simulate dislocations on a larger scale and for a longer period. By the implantation of the mentioned density-based sight, it would be possible to understand and predict some phenomena corresponding to collective motion of dislocations like strain localization, and hardening.  Moreover, by developing, and utilization of an effective continuous model for dislocations, it would be possible to bridge between a continuous model of dislocations and Crystal plasticity as the commonly used model for simulation of metals’ deformation on the macro scale. So, developing and focusing on the continuous modeling of dislocations would be a critical and effective way for multiscale modeling between meso-scale and macro-scale of deformation, and elimination of phenomenological coefficients on macro-scale.

In this presentation, there would be a short review of developed models for field dislocations density kinematics, firstly. Then, a very recent developed function for ‘all dislocation density field kinematics’ will be introduced. Finally, some preliminary results of simulations by the function will be presented.

Research Areas:

Advanced Materials

Contact for

Information

Prof. A.H.W. Ngan

+(852) 3917 7900

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