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Author: Subject: DIY measurement of energetic materials
Katie
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[*] posted on 26-4-2020 at 20:49
DIY measurement of energetic materials


I’m starting this thread to see what others have designed and/or tested in regards to measuring energetic materials (detonation velocity, pressure, brisance, overall power).

The most important aspect in test design is reliability. I doubt there are any DIY methods of obtaining accurate numbers, but there may be some test that can reliably compare energetics in a “more than or less than” sort of way.

Here’s my contribution. An energetic would be placed next to several very thin copper wires, each the same distance from each other with each wire being a set distance further away from the energetic. To these wires would be connected a simple electronic device that records the exact time each wire is broken by the explosion. Based off the distance from the energetic and the time each wire is broken (thus closing the circuit), one could calculate the velocity of the detonation wave much like police helicopters determine the velocity of a car by measuring how long it takes to drive between two separate points on the road of a known distance.

I don’t have the electrical engineering skill to construct this device, but I think it’s an extremely simple design possibly made easier by use of something like Arduino. If anyone knows of an affordable device that would be able to record the exact times at least two circuits are broken, or may be able to be adapted. If anyone has a high speed camera, they might be able to construct a circuit that powers two led lights and then simply review the footage frame by frame and record when each light goes out, but this would need to be a professional high speed camera. 240fps on your GoPro won’t cut it!

I’m also wondering if exploding identical pieces of glass and counting how many fragments are made could reliably measure brisance with actual numbers.

My last idea is to use a sound meter and compare energetics based on their decibel reading at a set distance. I would think this would be analogous to detonation pressure but I’m not sure if that is true or if affordable sound meters are sensitive and/or accurate enough to make comparisons via this method.

Any other ideas? I know the basic dent and hole measuring approaches but I feel like those kinds of tests are unreliable and unable to accurately measure smaller differences as in measuring samples of the same material, only with different densities, binders, etc.
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Etanol
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[*] posted on 27-4-2020 at 05:09


Metals stretch for a very long time before tearing. This is a crude method. The speed of detonation is measured with the exact opposite method. The appearance of electrical conductivity during the passage of a detonation wave is used. I measured the speed of several substances with home-made ionization sensors and an oscilloscope. This is a copper foil polyimide in foto.

The sound meter - is very good idea. But sound pressure does not correspond to detonation pressure, but to the total charge energy. Sorry for english:)
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ShotBored
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[*] posted on 28-4-2020 at 09:07


This might help you as it has a lot of different types of methods in there used in determining safety for transportation of explosive material. I know they have a few detonation and time to peak pressure tests using apparatus' that aren't too hard to build at home.

https://www.unece.org/fileadmin/DAM/trans/danger/publi/manua...
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Pyro_cat
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[*] posted on 1-5-2020 at 20:48


Quote: Originally posted by Katie  
I’m also wondering if exploding identical pieces of glass and counting how many fragments are made could reliably measure brisance with actual numbers.


I read that in a glass bottle the fast stuff is so powerful there are no glass shards flying it hits so hard it just turns the glass container to dust.

I cant find the article again search results all come up related to dust explosions.

You may find this interesting https://ceramics.org/ceramic-tech-today/ceramic-video/video-...

This too https://duckduckgo.com/?q=prince+ruperts+drop

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