# Nasty Last Year Project with Maths and Physics

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Ok, before anyone gets the wrong idea... I'm not asking you to do anything for me but me and my team are working on our final year project at university. We're making a program for a demolition company where explosion physics and maths are our greatest problem since we never have done something like this before. You're probably wondering why we would do a stupid thing like that. Well, firstly the other project proposals wasn't as good and secondly we saw it as a challenge. Well, the demolition company bores like 30m deep holes into a hill-side for a few rows and their seperated at a variable length. Somthing like this: 0 = hole - = hillside /------------------ ----------/ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Everything is basic in this program (which we can do) the only BIG PROBLEM is the math and physics behind such a thing. This is the Problem : The problem the company faces is that when two or more explosions go off, each creates a shockwave. When shockwaves cross, the intensity of the blast at that point is very high. This creates problems where accurate blasting is required. Is there anyone who have done something like this or something? Please could you point us in the right direction, we just need to know where to begin. Man this tuff is nasty. Thanks

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The shockwave has a velocity... and it's a wave... you need to model waves... nice, neat, simple, circular waves, with fixed velocities...

Infact, you don't even need to model them, unless your taking the composition of the medium into account...

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Ok, but that's not all.
There's this effect from Schnell's law (I think thats how you spell his name) from First Year's Electronic Physics (which someone has explained to me) where if 2 or more shockwaves, cross you get an effect where light traces moves through or gets reflected, like a window glass. The more reflective (I think) it gets the more dense the area is, they want that to be 3D.

But what formula could I use to calculate a shockwave blast? A simple circle-radius? I don't think that its that simple.

Anyway, thanks.

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If the matter has uniform density it will simply be an expanding spherical wave with a fixed group velocity, but the wave's frequencies will become more spread out as it gous in time too. Also, the intensity is going to drop with the increase in surface area of the wave.

I think you are going to find that without at least a coarse mapping of the structure of the ground that this will be horribly innacurate. You need to have an idea of the composition of the face, its density, etc. And then you can model it.

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Sorry, I'm not sure I understand: is this a game about a demolition company, or is there an actual demolition company that is going to use your program for simulation purposes, before doing demolition?

If the latter is the case, you might want to go for a more traditional (read trusted) simulation method, like finite elements. Even then, things like large discontinuities are very difficult to model accurately. At the very least, if you do your own modeling (assume spherical shock waves, etc.), I recommend you use your university's resources to do a NASTRAN / PATRAN simulation of the same model, and compare results.

Good luck.

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Oh, yeah this is for a REAL demolition company.

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Rutin
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