Plasticity of heterogeneous materials across scales; from polycrystalline metals to granular flow

Hesam Askari, Postdoctoral Associate at Massachusetts Institute of Technology (MIT)

Friday, November 6, 2015
1:30 p.m.

Hopeman 224

The deformation response of heterogeneous materials is arising from different sources within a wide range of length scales; from small atomic scales to continuum levels. At each scale, specific behavior is observed that can be represented using a constitutive approach. In this talk I present two structurally different families of problems in plasticity of heterogeneous materials; the case of crystalline metals where complexity is embedded within the micro-constituents, and the case of granular flow where it arises from complex rheology. I demonstrate how different levels of mechanism-based constituents can be bridged together to create a framework that can be used in variety of scenarios in plasticity of metals including forming, cyclic deformation and stochastic response. In addition, plasticity of granular materials based on a simple continuum approach will be presented. I show how such a complex system shows very simple rules with regard to resistive forces on intruders traveling within the media, featuring latest findings about the relationship between an empirical approach named Resistive Force Theory (RFT) and frictional plasticity.