My first academic paper has just been submitted to the publisher! I still can’t quite believe it. Submitting it doesn’t necessarily mean it will actually get published. The journal might refuse it outright, and even if they accept it, it will have to go to the reviewer, then come back to us, be corrected and then be sent of again. But still, I am really proud. I wrote the paper with two other people but I was surprised to find that they listed me as first author, which means the paper will mainly be cited under my name.
The contend of the paper doesn’t have much to do with theoretical physics. Last summer, I joined a research group in the Department for Material Sciences for two months and my results from that time have become this paper.
As you probably know, materials will expand or shrink when you heat them up or cool them down. Generally, things get bigger when they are heated up and smaller when they are cooled down but how much they grow or shrink depends on the actual material itself. If you know what to look for, you can see signs of this everywhere. Big bridges, for example, often have lines across them with a softer material in the cracks. This is so that the big concrete slabs of the bridges can expand or contract without ripping the whole structure apart. Old railroad tracks in warm places are often bent because they expanded in the heat but they didn’t really have any space so they bulge out sideways.
Most of the time, this expansion and contraction is no problem. For a start, it is generally quite small on an everyday scale. Secondly, most of the time things just have space around them. It does however become a problem if you have two materials stuck together very firmly, that expand and contract differently. This is especially bad when you have to deal with very large temperature changes, a few hundred degrees for example. When the layers try to expand, one will expand a lot more than the other. Things will start getting bent out of shape by the internal forces and eventually, the two layers will start breaking apart. In real life, this often forms quite intricate crack patterns. You can see an example of this in paint peeling of metal surfaces in winter.
I looked at a very simple situation of this kind, just two layers of different materials stuck together, and then modelled (using a computer) what happens when you heat this piece up or cool it down. When doing this sort of thing on a computer, one needs equations to describe all that internal pulling, the deformation and the expansion. The problem is that as soon as cracks form, these equations get in trouble because they don’t deal very well with having to work with a gap in the piece. Most of the time this is done using a method called the finite element method but the results have been a bit disappointing. The crack patterns were often much too simple in comparison to the real thing. I now tried to do the same thing using a new method called Peridynamics and it worked a lot better.
Keep your fingers crossed for me that this goes through!