A random bizarre question
Discussion
Great question.
There needs to be a lot more info in order to give an accurate answer, however initial thoughts are:
High explosive grenade I presume.
Then assuming preformed fragmentation, Buleys equation will define fragment throw. For non-preformed fragmentation use Motts Law.
Then use Gurney equation for pressure.
Also the grade and type of steel will need to be known for a detailed answer as well as grenade composition. But as minimum grenade nomenclature and steel thickness is required.
There are some proprietary calculation tools which would give you a correct answer but I don't have access to these when WFH.
My gut feeling is that it would probably contain it and might just crack the cube.
There needs to be a lot more info in order to give an accurate answer, however initial thoughts are:
High explosive grenade I presume.
Then assuming preformed fragmentation, Buleys equation will define fragment throw. For non-preformed fragmentation use Motts Law.
Then use Gurney equation for pressure.
Also the grade and type of steel will need to be known for a detailed answer as well as grenade composition. But as minimum grenade nomenclature and steel thickness is required.
There are some proprietary calculation tools which would give you a correct answer but I don't have access to these when WFH.
My gut feeling is that it would probably contain it and might just crack the cube.
Scrump said:
Great question.
There needs to be a lot more info in order to give an accurate answer, however initial thoughts are:
High explosive grenade I presume.
Then assuming preformed fragmentation, Buleys equation will define fragment throw. For non-preformed fragmentation use Motts Law.
Then use Gurney equation for pressure.
Also the grade and type of steel will need to be known for a detailed answer as well as grenade composition. But as minimum grenade nomenclature and steel thickness is required.
There are some proprietary calculation tools which would give you a correct answer but I don't have access to these when WFH.
My gut feeling is that it would probably contain it and might just crack the cube.
You would also need to take into account what explosive is used. RDX does not fully combust without access to atmospheric oxygen for example. There needs to be a lot more info in order to give an accurate answer, however initial thoughts are:
High explosive grenade I presume.
Then assuming preformed fragmentation, Buleys equation will define fragment throw. For non-preformed fragmentation use Motts Law.
Then use Gurney equation for pressure.
Also the grade and type of steel will need to be known for a detailed answer as well as grenade composition. But as minimum grenade nomenclature and steel thickness is required.
There are some proprietary calculation tools which would give you a correct answer but I don't have access to these when WFH.
My gut feeling is that it would probably contain it and might just crack the cube.
As already stated by my learned friends, without all the necessary information required it's a how long is a piece of string question, starting with the most basic facts of material specs and density, followed by grenade specs and then the exact dimensions of the void, how much space there is around the grenade, temperature of the material will also play a part.............and on.......and on......
Grenades fire by a vial of chemical setting off a small high energy charge which in turn starts the explosive train that creates a rapid gas expansion which breaks apart the frangible structure of the grenade.
This chemical reaction inside the grenade that makes it explode will not reach full completion as the grenade within the cube becomes a pressure vessel. Effectively arresting the gas generation phase as the surrounding air pressure and heat generated will change the chemical reaction process. This process in most explosives relies on the gas generated to be evacuated allowing space for more of the substance access to heat and air to react further.
By pressurising the grenade, and preventing the last stage of the explosive train from being exposed fully an incomplete explosion occurs.
When you consider that a relatively thin steel cylinder can contain 300bar of air in a breathing apparatus set then 1m3 steel cube will be able to contain the pressure of the incomplete chemical reaction in the grenade.
My take on this is that the steel cube will become a pressure vessel containing the high pressure gas by product of the grenade.
This chemical reaction inside the grenade that makes it explode will not reach full completion as the grenade within the cube becomes a pressure vessel. Effectively arresting the gas generation phase as the surrounding air pressure and heat generated will change the chemical reaction process. This process in most explosives relies on the gas generated to be evacuated allowing space for more of the substance access to heat and air to react further.
By pressurising the grenade, and preventing the last stage of the explosive train from being exposed fully an incomplete explosion occurs.
When you consider that a relatively thin steel cylinder can contain 300bar of air in a breathing apparatus set then 1m3 steel cube will be able to contain the pressure of the incomplete chemical reaction in the grenade.
My take on this is that the steel cube will become a pressure vessel containing the high pressure gas by product of the grenade.
You start with a void containing very hot gas at high pressure.
The contents of the void would cool rapidly as the cube is conductive.
You end up with a void containing room temperature gas at lower pressure.
The exact pressure would depend on the chemical reactions involved.
All the energy ends up as low grade heat (as does everything else in the world)
If you really nerd out on this, you might have created a plastic/elastic pressure vessel. It's been 30 years since I did this sort of stuff, but the theory is:
- you over pressurise the vessel
- the inside layer of the vessel exceeds the elastic limit of the material and is permanently deformed.
- the outside layer does not exceed its elastic limit, but is now compressing the inner layer.
- as a result, your pressure vessel is now MUCH stronger
Counterintuitive, but true.
The contents of the void would cool rapidly as the cube is conductive.
You end up with a void containing room temperature gas at lower pressure.
The exact pressure would depend on the chemical reactions involved.
All the energy ends up as low grade heat (as does everything else in the world)
If you really nerd out on this, you might have created a plastic/elastic pressure vessel. It's been 30 years since I did this sort of stuff, but the theory is:
- you over pressurise the vessel
- the inside layer of the vessel exceeds the elastic limit of the material and is permanently deformed.
- the outside layer does not exceed its elastic limit, but is now compressing the inner layer.
- as a result, your pressure vessel is now MUCH stronger
Counterintuitive, but true.
Edited by rxe on Wednesday 14th April 14:28
rxe said:
You start with a void containing very hot gas at high pressure.
The contents of the void would cool rapidly as the cube is conductive.
You end up with a void containing room temperature gas at lower pressure.
The exact pressure would depend on the chemical reactions involved.
All the energy ends up as low grade heat (as does everything else in the world)
If you really nerd out on this, you might have created a plastic/elastic pressure vessel. It's been 30 years since I did this sort of stuff, but the theory is:
- you over pressurise the vessel
- the inside layer of the vessel exceeds the elastic limit of the material and is permanently deformed.
- the outside layer does not exceed its elastic limit, but is now compressing the inner layer.
- as a result, your pressure vessel is now MUCH stronger
Counterintuitive, but true.
All good stuff. It was just getting my head around a bit explosion in a tiny immovable contained area.The contents of the void would cool rapidly as the cube is conductive.
You end up with a void containing room temperature gas at lower pressure.
The exact pressure would depend on the chemical reactions involved.
All the energy ends up as low grade heat (as does everything else in the world)
If you really nerd out on this, you might have created a plastic/elastic pressure vessel. It's been 30 years since I did this sort of stuff, but the theory is:
- you over pressurise the vessel
- the inside layer of the vessel exceeds the elastic limit of the material and is permanently deformed.
- the outside layer does not exceed its elastic limit, but is now compressing the inner layer.
- as a result, your pressure vessel is now MUCH stronger
Counterintuitive, but true.
Edited by rxe on Wednesday 14th April 14:28
I hated Thermodynamics at Uni. Only specific heat gravity work interested me!
3rd year Thermodynamics taught me:
- I wasn't as good at Maths as I thought I was.
- I was not cut out to be a Chemical Engineer
- That 4th year thermodynamics was going to be horrific (turned out to be true)
- That FORTRAN was useful, and that I should have a career involving computers....
- I wasn't as good at Maths as I thought I was.
- I was not cut out to be a Chemical Engineer
- That 4th year thermodynamics was going to be horrific (turned out to be true)
- That FORTRAN was useful, and that I should have a career involving computers....
It's not what would happen, but it reminds me of an explosive hydroforming video I was looking at the other day:
https://www.youtube.com/watch?v=96yhdnhPxAw
https://www.youtube.com/watch?v=96yhdnhPxAw
rxe said:
You start with a void containing very hot gas at high pressure.
The contents of the void would cool rapidly as the cube is conductive.
You end up with a void containing room temperature gas at lower pressure.
The exact pressure would depend on the chemical reactions involved.
All the energy ends up as low grade heat (as does everything else in the world)
If you really nerd out on this, you might have created a plastic/elastic pressure vessel. It's been 30 years since I did this sort of stuff, but the theory is:
- you over pressurise the vessel
- the inside layer of the vessel exceeds the elastic limit of the material and is permanently deformed.
- the outside layer does not exceed its elastic limit, but is now compressing the inner layer.
- as a result, your pressure vessel is now MUCH stronger
Counterintuitive, but true.
Autofrettage nicely explained. The contents of the void would cool rapidly as the cube is conductive.
You end up with a void containing room temperature gas at lower pressure.
The exact pressure would depend on the chemical reactions involved.
All the energy ends up as low grade heat (as does everything else in the world)
If you really nerd out on this, you might have created a plastic/elastic pressure vessel. It's been 30 years since I did this sort of stuff, but the theory is:
- you over pressurise the vessel
- the inside layer of the vessel exceeds the elastic limit of the material and is permanently deformed.
- the outside layer does not exceed its elastic limit, but is now compressing the inner layer.
- as a result, your pressure vessel is now MUCH stronger
Counterintuitive, but true.
Edited by rxe on Wednesday 14th April 14:28
I worked on a project some 35 years ago to design and make a "closed vessel" in which various small amounts of explosives were detonated. Various sensors monitored the burn and computers analysed the results.
Then, the resulting pressure was released, as RXE says, once cooled down the pressure was much lower but would still destroy a valve that was supposed to be good for 35MPa and therefore expensive. I think it was due to the corrosive nature of the gases being released rather than pressure alone.
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