iMechanica - ES 240 - Comments

Analysing a Horizontally curved Beam/girder

mithila — Sun, 10 Aug 2008 09:02:59 -0400

hi,

can tou tell me the way of analysing a horizontally curved beam by ABAQUS?

can anyone tell me what are

omid2008 — Wed, 30 Jul 2008 13:03:07 -0400

can anyone tell me what are the differences between ANSYS and Abaqus?

Composite and Adhesive modelling in abaqus

arunachetty — Tue, 29 Jul 2008 17:45:11 -0400

hello

i am arun and am doin my msc in astronautics at cranfield university,uk, and am using abaqus to simulate a single shear composite to metal bolted/bonded lap joint using solid elements for my thesis

could you please advise me on how to model composite laminates using solid elements?

could you also please advise me how to model the adhesive that joins the composite and metal substrates and what type contact conditions should i specify?

i will be most grateful if you could respond to my query, Thank you very much

ground coupled heat pumps

mohamedali — Mon, 21 Jul 2008 05:37:55 -0400

thank you

do you have any tutorials to learn hoe to use abaqus for ground coupled heat pumps

Rui:your initial guesses are correct,but people are NOT careful!

Mike Ciavarella — Sun, 20 Jul 2008 03:51:08 -0400

Rui,

to complete Jim Barber's replies to your question (he actually raised also some more questions) you probably know that you can formulate many problems (for example contact and crack problems) by using displacement DERIVATIVES, and this avoids the problem of the rigid body motion. You can find this also in Barber's book.

To comment on your more recent question, of course strictly speaking ALWAYS at the surface there is a state of plane stress, by definition, as well as ALWAYS there is a TENDENCY to have some stress inside. The stress increases towards the limit plane strain one, that as you know depends on Poisson's ratio s3= nu * (s1 + s2) so this is EXACTLY zero generally only for Poisson=0, or else if the state is of pure shear.

You are rigth that in standard fracture mechanics testing this is more or less known, but I can promise you that in many situation, this is disregarded! For example, I have submitted a paper about Paris' law which shows how the size of the specimen is OFTEN disregarded in what affects the Paris "constant" C and m ---- so people are NOT careful and only GI Barenblatt has strongly commented on this before

The paper is not accepted yet, but you can find a little however in the Paris seminar I did recently A seminar at Paris VI inst. d'alembert - One, no one, and one hundred thousand crack propagation equations: thursday June 5th. 1

Regards, Mike

Re: Flamant Solution - a fine math

Ajit R. Jadhav — Sun, 20 Jul 2008 03:22:25 -0400

OOPS... I realize only now that in my yesterday's post above, there should have been a linefeed or two just before the preface: "(Please correct me if I am wrong here.)" so that that preface would have become separate and got applied to the entire matter following it. Sorry!
Similarly, I did not *actually* mean to imply that Rui was groping... Actually, the groping and grappling is all mine.. I have been thinking of this conjecture to the effect that the approaches like the random walk ought to work out for tensor fields like those of elasticity too... In the final editing of my draft, the placement of that statement went wrong too.

(These days, I first write in a Notepad file my comment, and then, just copy-paste the contents in the TinyMCE or so editor here, because the Internet, the editor (in IE) and the electricity can all crash any moment. So, I first write and then do copy-paste. But still, after such a copy-paste, something more strikes me, and so, I want to revise the initial draft. Sometimes, I end up introducing silly mistakes in this process...)

Anyway, let me take that conjecture off this thread. So, if anyone is interested in discussing it, drop me a line or feel free to start a new thread on that one. Thanks!

-----

Just one more point: Yes, Prof. Barber's comment was remarkable in the sense that despite his background, he spoke of the "a finite system --> an appropriate limiting process --> a higher abstraction involving an infinity" kind of approach. That view is so very unusual to find with mechanicians or applied mathematicians (let alone "pure" mathematicians). I really enjoyed it, too...

-----

...I must wind up or else I can go on and on and on...

Flamant Solution - a fine math

Rui Huang — Sat, 19 Jul 2008 16:10:35 -0400

Ajit's comment seems to bring this discussion to a higher level in terms of mathematics. However, my original question was a humble one. It is not about math. I was trying to understand the physical reality (e.g, the infinite displacement at the remote boundary). It is now understood (thanks to all the comments above) that this is impossible with the physically unrealistic model (e.g., 2D, infinite domain). Jim Barber's comment pretty much resolved my concern.

Re: Flamant Solution -- Is it about 2D vs 3D a la Polya?

Ajit R. Jadhav — Sat, 19 Jul 2008 13:39:41 -0400

Thanks to Biswajit's comment above (no. 7930 dtd. 27 June, 2008) for bringing this fine thread to notice again.

With the benefit of some hindsight, let me add the following:

From his writing, I think that Rui isn't here completely concerned only with the unboundedness of displacements even in the case that the stress drops as 1/r with distance.

Thus, the issue of specifically marking out the difference of the strain field (namely, that it is finite) from the displacement field (namely, that it is infinite) does not appear to be his sole concern here.

That issue---of strains vs. displacements---would be too simple a matter... By way of a simple analogy (and please permit me one), it would be like saying that even if the net yearly population growth rate of a nation (i.e. the analog of strain) goes on reducing monotonically, its actual total population (i.e. the analog of displacement) would continue to grow in an *unbounded* manner (or tend to infinity in infinite time) provided that net growth rate were to be a +ve number. I mean, all this is too simple a mathematics, and, judging by his writing, I guess, someone like Rui wouldn't be concerned with it. (Please correct me if I am wrong here.)

I think Rui here is trying to make a truly fine observation about the essential difference of behaviour in between the 2D and the 3D situation.

In particular, I think that Rui's query (and call it groping/grappling if you wish), when put in a wider context, is about a continuum (tensor) elasticity version of that which is known as Polya's recurrence theorem in the discrete electric network theory. (For a discussion of the latter theory, for example, see: Doyle and Snell, "Random Walks and Electric Networks," arXiv:math.PR/0001057). Such a thing may not be possible in complete generality. (In any case, I haven't thought separately about it---whether it would be possible or not.) But at least, that kind of a definitive and essential difference between the 2D and 3D situations is what Rui seems to be hitting at.

Could any mathematician please shed some light on this matter? (I would have loved to answer this question definitively, but, mathematics, as such, has never been my main interest in life---not even a side interest, for that matter.) Thanks in advance for any clarification (which is also accessible to an engineer like me).

need help with ABACUS

nina333 — Wed, 09 Jul 2008 13:24:09 -0400

hello Lu,

I do thank you for your tutorials. But as i have tried the CAE example and i just manged to let work i tried to do my own model by creating part and i wanted to divide it but i did not find any help neither in simuli or tutorial or any other source to guide me on what i want to do basically. I hope if you can help me by emailing me so i can ask you directly please.

nl1422@hotmail.com

thank you

Nina

update on Tutorial for Abaqus UEL subroutine

Y. Kajee — Mon, 30 Jun 2008 08:25:22 -0400

Greetings

I have recently begun work on developing my own user element in abaqus. It is not as easy as I thought it would be.

Have you had any luck finding any tutorial or other help on UEL subroutines since your post here?

Regards

Re: Flamant solution

Biswajit Banerjee — Thu, 26 Jun 2008 21:40:36 -0400

Recently I revisited this excellent discussion on the Flamant solution in linear elasticity (we need more such discussions on iMechanica). However, one of the problems that I noticed in the discusion was that the Flamant solution was not really explained to the uninitiated reader. Given that many of our readers may be new to linear elasticity, I went ahead and added a page on the Flamant solution to Wikpedia (based on Prof. Barber's book). You can find it at http://en.wikipedia.org/wiki/Flamant_solution.

Please add some insights and correct any mistakes in the article.

-- Biswajit

Thanks!

zhangqian — Sat, 07 Jun 2008 02:17:38 -0400

Thanks for your excellent work,Mandam!

I love mechanics!

need urgent help

nina333 — Fri, 23 May 2008 18:04:13 -0400

dear all

I need help in my work i started to work with ABACUS and i suppose to work with shoulder data to review the reverse implant inside this shoulder.

i can not explain this very well but i need some expert in ABACUS to ask them what to do exactly or at least get me started.

Pleaseeeeeeeee i need an URGENT help......FROM ANY ONE.

please reply to me on: nl1422@hotmail.com

Thank you

Nina

Please try the solid

Kewei Li — Fri, 23 May 2008 09:51:01 -0400

Please try the solid composite property in ABAQUS 6.7. It is designed for this problem.

Good luck in your research!

Kewei Li

Shanghai University

Using MATLAB functions/scripts in user interfaces in ABAQUS

alankar — Tue, 20 May 2008 22:00:27 -0400

Hi,

Could anybody please let me know if it is possible to use MATLAB functions/scripts in ABAQUS user interface UMAT ?

Regards ,

Alankar
Ph.D. Student
School of Mechanical and Materials Engineering
Washington State University, Pullman