building optimal networks: first set of equations that satisfy isotropy condition second set of...

Building optimal networks:

First set of equations that satisfy isotropy condition

Second set of equations that satisfy mechanical equilibrium

Equilibrium conditions, along with the isotropy conditions, constitute a set of necessary and sufficient conditions for an affine, stretch-dominated deformation:

N. Francois et. al, “Experimental investigation of the mechanical stiffness of periodic framework-patterned elastomers”, Philosophical Transactions of the Royal Society A (2014)

Searching EPINET for optimal nets

Initial search limited to simple cubic symmetry and transivities {1,1}, {1,2} and {2,1}. Found two (out of 74 candidate) structures.

SQC38SQC1649

PVS

+

EPINET

Building the nets: TemplatingCAD models

3D printed

Tomogram sqc38:2048x2048x2048voxel~0.0433

sqc38

Finite Element simulations vs experiment

SQC38

SQC1

Snippets of recent publications on granular materials:

In this paper we show, for the first time, that there are two types of contacts in a granular assembly (mechanical and geometrical contact) and that the mechanics of granular systems is governed by only the “mechanical contact” not geometrical contact.

Snippets of recent publications on granular materials:

PRE 2015:

We provide full description/characterisation of order-disorder transition in granular systems. We show the mechanisms with which granular systems can crystallise and we explain why FCC is the dominant structure instead of HCP despite having similar packing density.

Main message: Existence of random/disordered mechanical backbone in highly crystallised packings.

Snippets of recent publications on granular materials:

We show that the global contact numbers of frictional sphere packings and ellipsoids can be explained by a combination of local contact function and a conditional probability.

Main message: We find the relationship between local properties of grains with global contact number.