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Up Topic Welding Industry / Technical Discussions / Gaussian vs non-Gaussian (EB vs GTAW)
- - By mightymoe (**) Date 04-17-2010 02:07
What exactly is "Gaussian"? I read an article on Wikipedia but I just didn't get it.
Can someone please explain to me the difference between Gaussian and non-Guassian?
Please type slow and keep it as simple as possible (I'm no rocket scientist).
Thanks
Parent - - By ssbn727 (*****) Date 04-17-2010 13:01 Edited 04-17-2010 17:35
Hi mightymoe!

These links may help out... Perhaps these articles may enlighten you... Although I warn you, the math isn't for the faint-hearted!!!
Note: Giovanni! You may be interested in the first two links! ;-)

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-58782003000300013

http://www.scielo.br/pdf/jbsms/v25n3/a13v25n3.pdf

Here is a very interesting article regarding software capable of solving various equations related to welding, casting, upsetting and extrusion computational modeling and thermal stress analysis, etc.

http://www.dynamore.de/documents/papers/euro4/implicit-new-developments/heat-transfer-in-ls-dyna

These are from our friend @ MIT in Cambridge, MA:

http://eagar.mit.edu/EagarPapers/Eagar032.pdf

This one I'm not familiar with it because I haven't had a chance to read it yet:

http://files.aws.org/wj/supplement/05-2000-BONIFAZ-s.pdf

This one is from India:

http://maja.uni-mb.si/files/apem/APEM3-2_093-105.pdf

Here are the Gaussian system of units:

http://physics.info/system-gaussian/

This one is from Ohio State University:

http://iwse.osu.edu/wefaculty/farson/WE804Web/8%20WE804%20Laser%20Heating.ppt

Here is the official Gaussian website, but now we're getting really deep down to the atomic level which may not be what you're looking for:

http://www.gaussian.com/index.htm

http://www.gaussian.com/g_whitepap/thermo.htm

This is from our friends from across the pond in the UK with Cambridge's own Bhadeshia co-authoring this paper on laser spot welding:

http://www.msm.cam.ac.uk/phasetrans/2003/laser.welding.De.STWJ.2003.pdf

Here's a link for all of you who dare to expand beyond the average bounds of mathematical curiosity:

http://mathworld.wolfram.com/GaussianFunction.html

This one is truly an excellent MSN Word .doc format article:

http://www.cham.co.uk/PUC/PUC_Luxembourg/Presentations/GreenwichU_Hughes.doc

Here is a very interesting patent application named:"Method for determining a heat source model for a weld."

http://www.freepatentsonline.com/6324491.pdf

There are more .pdf's relate to this article in this link:

http://www.freepatentsonline.com/6324491.html

Well that's about it for now! ;-) Enjoy the reading!!! ;-) ;-) ;-)

Respectfully,
Henry
Parent - - By mightymoe (**) Date 04-17-2010 14:09
Very Interesting reading. Thanks Henry.
It seems that "Gaussian' refers to a conical shaped power/heat source that can be accurately measured and uniformily applied.
EB welding is Gaussian but GTAW is not.
Is there a mathmatical formula which explains/defines GTAW instead of saying what it is not ( non-gaussian)?
Further insight and or correction would be greatly appreciated.
Parent - - By ssbn727 (*****) Date 04-17-2010 17:41
I believe you may find what you're looking for in this article which talks about the two types of heat distribution equations such as the ellipsoidial and gaussian models which the author get into more in depth here:

http://files.aws.org/wj/supplement/05-2000-BONIFAZ-s.pdf

And in this one from Professor Eagar of MIT:

http://eagar.mit.edu/EagarPapers/Eagar036.pdf

Hopefully this is what you're looking for. ;)

Respectfully,
Henry
Parent - - By mightymoe (**) Date 04-17-2010 18:28
Ellipsoidal! Yes that's what I was looking for.
It was mentioned in a previous article that you posted but I missed it.
The more I learn the more I realize that I don't know.
Thanks again Henry!
Parent - By ssbn727 (*****) Date 04-17-2010 18:33
You're "Weldcome!!! ;) :) :)" BTW, The same goes for me also!!! :) :) :)

Respectfully,
Henry
Parent - - By SWP (**) Date 04-19-2010 14:12
Apparently it is very difficult to get accurate measurement of the GTA arc energy distribution, but researches such as Dr. Tsai have suggested the GTA arc to be gaussian.  It is fairly simple to get a precise measurement of the EB distribution.  Dr. Paul Burgardt used a modified faraday cup to measure EB power distribution and showed it to be gaussian.  Dr. John Elmer used a similar faraday cup arrangement and analysis software and showed that the EB is largely gaussian in cross section but that it can have some non-uniformity when viewed in 3-d.  The EB power profile can acutually reflect the shape of the filament in the gun, and it can create a rectangular foot print on the workpiece.

This article addresses a comparison GTA with matching power level conduction EB welds, and suggests that since the EB welds cannot replicate the shape of GTA, then GTA must not be gaussian.
http://files.aws.org/wj/supplement/Pierce/ARTICLE3.pdf
Parent - By mightymoe (**) Date 04-24-2010 00:28
Thanks for your cliff notes on that article. I read your post for the second time and I now understand what you wrote.
Parent - - By Metarinka (****) Date 04-23-2010 17:34
I'm curious what you want to do with this information?

it seems alot of these models are too abstract to be applied in the less than ideal conditions of real life welding.

That being said I love to read about this stuff.
Parent - By mightymoe (**) Date 04-24-2010 00:10
In another post I asked about the differences between 304L.
A reply contained a link to some very interesting reading. In the info. it refered to Gaussian and non-Gaussian.
I just wanted to understand what I was reading.
Up Topic Welding Industry / Technical Discussions / Gaussian vs non-Gaussian (EB vs GTAW)

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