Size Effects and Scaling in Discrete Dislocation Plasticity
<-- Return to the list
Date: 10-21-2005
Start Time:
4:00pm
End Time: 5:00pm
Speaker: Alan Needleman
From:
Brown University, Providence, R.I.
Location: 1306A Mudd
Hosted by:
Center for Integrated Science
Abstract:
Plastic flow in crystalline materials is size dependent over length scales of the order of tens of microns and smaller. This size dependence arises in a variety of contexts; e.g. the grain size dependence of the flow strength, the indentation size effect and the size dependence of the thermo-mechanical response of thin films. One well-appreciated origin of size effects is associated with imposed plastic strain gradients and geometrically necessary dislocations. In addition, strain gradients and boundary layers leading to size-dependent response can occur in circumstances where, at least in principle, a more or less homogeneous response is possible but where the physics of dislocation motion prevents it. Discrete dislocation plasticity analyses of various plastic flow processes will be used to illustrate a range of size effects. Particular attention will be given to the scaling, both with size and with material properties that is predicted by the calculations.