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Path Dependency

The Research

Understanding the mechanical and microstructural properties of metals is of great importance both in terms of the fundamental science involved and also in the application of this science owing to the high level of usage of metallic objects. A variety of models are available to predict the response of metals in various situations, with varying levels of physical basis. An important area which is not well understood is how these different models can be applied to predict material behaviour with increasing strain rate, leading onto failure, particularly as a function of the initial condition of the material. This knowledge of the original state is known as path or history dependence.

Symmetric Taylor
Aluminium rods undergoing symmetric Taylor impact.

 

Completely characterising path dependence requires a wide range of experimental techniques. Most notable are those at medium to high rates, such as Split Hopkinson Pressure Bar experiments, where effects caused by sample inertia need to be discerned from the true material response.

Numerical simulation is key to applying and testing the models which are used to predict this behaviour. The research carried out in this group aims to aid in the parameterisation of these models, and to develop them to better describe the experimentally observed nature of path dependence.

The People

Lewis Lea is currently undertaking a PhD sponsored by the Engineering and Physical Sciences Research Council, and QinetiQ, and is overseen by Dr. Andrew Jardine.

The Impact