chief - 29-4-2010 at 23:51
By the elasticity of rubber one might have the idea
==> that it will withstand conditions where steel would shatter ...
I personally would bet against it, since the velocity of sound in rubber is very low (only 10s of m/s) and my theory is, that anything shatters that
has a > 30% smaller velocity of sound than the VOD of the applied explosive ...
How is it in reality ?
==> Will a pyro-cracker, placed within a bicycle-tube, overblow it ?
==> What will a droplet of some ETN or whatever do to a 2 or 5 mm-thick piece of rubber ... eg. could a car-tire be punctured with a similar charge
as for a metal-plate of the same dimemsions ?
==============
Question would be: Can a smaller explosion be safely contained within rubber ?
[Edited on 30-4-2010 by chief]
Lord Emrone - 30-4-2010 at 03:55
This isn't an answer, but if you cut rubber, there is a big risk of static electricity. 50 ml MEKP exploded near my hand when I poured it in a rubber
tube.
quicksilver - 30-4-2010 at 05:46
You'd really have to experiment: you got too many variables there...... Some bike tires are fairly heavy, you have a heat blast from flash but ETN
isn't so hot - as it dets (in small amounts - fast as NG, etc, etc
There are several whole threads on methods to experiment in silence (there is a large one on silence & containment) & safely. There are
various techniques. Some of them I've used with a great degree of success! There was even a "blast box" design with baffles (like a silencer) that was
used at Austin Powder Works (IIRC). I once found a test box (all rusted and messed up) at Benson, AZ that I tried to lug back.
The issue re: static is true and profoundly serious. Buried car tires are grounded. But static IS a killer... A long time back I developed a habit of
grounding myself & checking one more time when ever I touched something energetic
[Edited on 30-4-2010 by quicksilver]
JohnWW - 30-4-2010 at 17:59
Rubber is used in gun silencers. A few years ago, I downloaded some ebooks from roguesci.org on the design of silencers, which I still have
somewhere. Although they have perfectly legitimate uses on guns such as avoidance of scaring away non-targeted game when out hunting, in some
jurisdictions they are illegal to sell or possibly possess or use, making it necessary to improvise one's own silencers.
franklyn - 30-4-2010 at 20:28
You forget the momentum imparted to the envelop of rubber.
It will propel itself to pieces
.
chief - 30-4-2010 at 23:47
The idea came from this: Since the rubber is elasctic it might possibly withstand some deformation ... to a extent where steel would shatter ...; a
bit away from the action the pressure-wave will be much weaker, since the gases expand into the volume ... giving sort of a a 1/r³ - weakening ..
The question I had in mind was if a barrel could, for safety, be surrounded by eg. several layers of bicycle-tubes, to avoid most of the danger in
case it shatters ...
==> There are some youtube-videos, where live it can be seen, that even new hunting-rifles have the barrel split in 2, somewhere from the middle on
..., when the people hunt some deer ... : So maybe at least the parts of the barrel could be contained, prevented from hutring someone ... ...
quicksilver - 1-5-2010 at 05:47
That was the proposed purpose of a "blast mat" that is commonly used in industry when small or shaped charges may have a greater effect on surrounding
concrete, stones, etc. I understand where you're going here. It's variable depending on the circumstances, naturally. But it could function if the
rubber were re-enforced or the charge light enough. I saw some car tires, stacked and buried in sand, some 5' deep - forming a pit for this purpose.
Obviously, you need either some seriously re-enforced rubber (like a blast mat) or a really light charge, etc. as Franklyn pointed out, it's possible
that you'd get pieces flying - especially if done at low temp ranges or a charge greater than the physics of the elasticity could cope with.
There IS a formula somewhere that is useful here. The distance of a given blast diminishes in work provided by the distance from ("ground zero") a
starting point to containment proximity. But naturally I don't remember it. I think it's in DETONATION by Fickett & Davis.
franklyn - 1-5-2010 at 11:43
@ chief
Some people thought one could go over Niagara falls like
that , some were never found.
Blast mats are woven nets of wire rope (cable) the size of
concrete re-bar. Mass is all important to keep it from being
sent flying.
.