Supervisor: Dr Bill Proud
Many models exist for describing the shock behaviour of granular systems. Some, such as the p-alpha model, come from studies of metals with low (<5%) porosity. Other models can be described as "curve-fitting". Overall many granular systems, such as sand, can easily be 40+% porous. One issue is that, while in some cases the final state can be "predicted", the details of the compaction process are missed completely.
The aim of this PhD is to address these high-porosity materials in a systematic fashion. Factors to control will be grain size, grain strength, ductility, fracture limit morphology and particle size distribution.
By having the ability to control the ratio of the effects of void collapse, to grain fracture to overall porosity - different physical processes can be brought to the fore.
Recent theoretical advances in understanding granular materials, as entropic entities at low translation temperature (the grains do not move much in relation to one another, so they have effectively a low pressure-temperature state between the grains). Similarly it has been shown that systems of mono-modal (all the same size), spherical particles do not provide the necessary conditions for understanding naturally occurring systems.
References:
1. The introductory section of the WG Proud paper on sand response over a wide range of strain rate - SCCM 2007.
2. Theoretical aspects - the research of Dr Raphael Blumenfeld and Prof. Sir Sam Edwards.