 | | From: | rjkhan | | Subject: | Sudden rupture of Al foil | | Date: | 9 Jan 2005 00:01:44 -0800 |
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 | Hi
For a given shape of an Aluminium diaphragm and its thcikness, at
precisely what tensile stress will it rupture in case of sudden
development of pressure differenitial across its thickness. Can it be
related to the static UTS of Al foil. If yes then how...
If an impact testing equipment is required for this then how to
translate its result into MPa (Static Tensile stress). The reason is
that usually only static UTS is available in tables
Thanks
RJ Khan
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| | From: | brian stahl | | Subject: | Re: Sudden rupture of Al foil | | Date: | 10 Jan 2005 22:03:01 -0800 |
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| Would it be possible to have some sort of pin or probe that punctures
the "bubble" once it bulges a certain amount? I would think that
determining how much an aluminum dome bulges under a pressure
differential and having some sort of puncturing device would be easier
than designing the dome to burst at a given pressure differential.
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| | From: | Gregory L. Hansen | | Subject: | Re: Sudden rupture of Al foil | | Date: | Tue, 11 Jan 2005 15:09:52 +0000 (UTC) |
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| In article <1105423381.500048.166080@f14g2000cwb.googlegroups.com>,
brian stahl wrote:
>Would it be possible to have some sort of pin or probe that punctures
>the "bubble" once it bulges a certain amount? I would think that
>determining how much an aluminum dome bulges under a pressure
>differential and having some sort of puncturing device would be easier
>than designing the dome to burst at a given pressure differential.
>
That's called a burst valve. They're overpressure valves that are never
meant to open, but are installed to prevent explosions of pressure
vessels. An example is putting one on the main vacuum chamber of a
crystat, the danger there being that if air leaks in and freezes on cold
surfaces for some period of time, a great deal of pressure can develop
when it's warmed up. Burst valves are ultra-high vacuum compatible, while
o-ring sealed pressure relief valves aren't.
You can buy burst valves from a variety of companies like NorCal and Kurt
J. Lesker.
--
"'No user-serviceable parts inside.' I'll be the judge of that!"
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| | From: | Uncle Al | | Subject: | Re: Sudden rupture of Al foil | | Date: | Sun, 09 Jan 2005 12:27:50 -0800 |
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| rjkhan wrote:
>
> Hi
>
> For a given shape of an Aluminium diaphragm and its thcikness, at
> precisely what tensile stress will it rupture in case of sudden
> development of pressure differenitial across its thickness. Can it be
> related to the static UTS of Al foil. If yes then how...
>
> If an impact testing equipment is required for this then how to
> translate its result into MPa (Static Tensile stress). The reason is
> that usually only static UTS is available in tables
If you look at calibrated rupture diaphragms you will note one or two
subtleties:
1) The center is scribed with a cross or dimple, and or
2) There is a sharp which the bulging diaphragm hits, triggering
failure.
One can engineer a thin dome that will burst beyond a given
differential pressure. Engineering one that will spontaneously burst
at a definite differential pressure is a truly nasty problem. It is
severely impacted by material flaws, mounting, and corrosion.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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