iMechanica - ABAQUS - Comments

about FSW and LBW

Xiaoteng Wang — Mon, 06 Oct 2008 06:20:58 -0400

Hi Mirko,

I think FSW is quite different from laser beam welding. Although both of them are joining process, the mechanism of FSW is far away from the traditional arc welding. So before your start, please decide which branch you should choose because both are not so easy to study. For FE simulation, I only carried out FEM calculation of arc welding, such as TIG, MIG and Laser. I highly recommend you to read Goldak's first paper of double eclipsoid welding pool model:COMPUTER MODELING OF HEAT-FLOW IN WELDS, METALLURGICAL TRANSACTIONS B-PROCESS METALLURGY 17 : 587 1986. That paper is a classical work.Another review is also good: Modeling of fundamental phenomena in welds,T Zacharia / J M Vitek / J A Goldak / T A DebRoy / M Rappaz / H K D H Bhadeshia,Modelling and Simulation in Materials Science and Engineering,3 (2), p.265-288, Mar 1995.

I dont know if the newest version of ABAQUS provides the Goldak model or not. But another FE software MSC.MARC has already succeeded in implementation of Goldak model as GUI module. Anyway you can implement the model easily using subroutines.

FSW is still very difficult to model, because the FSW is not simply melt and solidification process. Dynamic recrystallization taks place dramatically in FSW. I think the FE simulation of FSW is much more difficult than arc welding.

I'm not sure what kind of problem you are interested in, but from what you described, I think your work may be related to residual stress/strain after welding or joining process. I think it is very challenging problem because of the highly nonlinear material properties and coupled phenomena. Good luck.

Best regards.

Wang

Structural effects due to thermal influences (e.g. laser, FSW)

Langhorst — Sun, 05 Oct 2008 07:52:21 -0400

Hello to everyone

I am doing my PhD at the Technical University of Munich (Germany)
and I want to simulate the structural effects of work pieces due to the thermal influence
of manufacturing processes like laser-beam-welding, laser-beam-cutting or
friction-stir-welding. Unfortunately I am more or less a beginner in ABAQUS,
but perhaps you can give me an advice how to start (a special tutorial for
thermal problems) or if it’s possible to simulate these kind of problems at all.

I would be deeply grateful for any help and

thanks a lot in advance

Mirko

Abaqus Process Automation Portal

Sprunger — Mon, 29 Sep 2008 13:11:49 -0400

Hello, Re: Sharing Abaqus UMAT and VUMAT subroutines.SIMULIA has an “Abaqus Process Automation Portal” http://www.simulia.com/PAPortal/This portal provides a mechanism to the SIMULIA (Abaqus) community for collaboration through discussion forums for GUI customization and scripting techniques. Users can upload, download, and share solutions and process automation components.

The Abaqus Process Automation Portal is approaching its 5 year anniversary and many engineers found it to be a useful resource. Almost 3000 registered members currently exist and this number continues to increase steadily.

Regards, Rene

Re:

alankar — Wed, 24 Sep 2008 18:36:12 -0400

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

hi Alankar

Yuanpei Duan — Wed, 17 Sep 2008 22:01:02 -0400

hi Alankar,

Could you help me about this question? Thank you very much!

http://www.imechanica.org/node/2909#comment-8695

Re:

alankar — Wed, 17 Sep 2008 11:15:46 -0400

Hi Phamhung,

Thanks for taising the question again. I think the problem is with incompatibility of MATLAB drivers with in ABAQUS environment. I wrote to Simulia for this and they said no. I am hoping that somebody has written small patch of trick code/driver for such connection.

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

Abaqus and UMAT

phamhung — Tue, 16 Sep 2008 08:46:58 -0400

hi all

I just repeat the same question of Alankar "

"Connecting ABAQUS with MATLAB"

I don't know if the Umat subroutine in Abaqus can be writen by matlab

and I also read a text from abaqus documentation :

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"A FORTRAN compiler is required to compile and link user subroutines for
Abaqus. If you prefer to write user subroutines in languages other than
FORTRAN, you must have the FORTRAN compiler specified, a compiler for your
language, and the knowledge of how to call routines in your language from
FORTRAN. SIMULIA cannot guarantee compatibility of Abaqus with user subroutines
written in programming languages other than FORTRAN".

anyone had been successful with Matlab?

Thanks

Hung

Phd Graduate student

Great Work

Nisarg Patel — Tue, 16 Sep 2008 03:33:10 -0400

Thanks nanshu lu.....for share tutorial with others....

Dr. Govindjee, Thank

srihari — Mon, 08 Sep 2008 11:27:49 -0400

Dr. Govindjee,

Thank you very much for the report.

Srihari

Finite deformations in a rotating frame

Sanjay Govindjee — Fri, 05 Sep 2008 21:29:40 -0400

There are several nice descriptions of how this works. (1) is one of the original papers by Oden and Lin 1986 (CMAME) [but beware they forgot about objectivity in the material formualtion for their viscoelastic model] (2) is a nice paper by LeTallec and Rahier 1994 (IJNME). Attached is a short report we wrote on the matter a while back. This, modulo, some implementation issues is how the formulations and computations work.

http://www.ce.berkeley.edu/~sanjay/ucb_semm_1998_02.pdf

Prof. Dr. Sanjay Govindjee
University of California, Berkeley

Re: Spin softening

Biswajit Banerjee — Thu, 04 Sep 2008 23:12:12 -0400

Abaqus appears to approach the problem in a different way. The manual says " It is assumed that the model (or that part of it to which these [centrifugal] forces
are applied) is described in a coordinate system that is rotating with
an angular velocity ...". The details, for Abaqus v 6.5-1, are in Section 6.1.1 "Centrifugal, Coriolis, and rotary acceleration forces".

For analytical solutions for a disk (in the nonlinear elastic context), see Problem 5.2.6 and Problem 5.3.7 of "Nonlinear Elastic Deformations" by Ray Ogden. Once you know the strain energy function you can calculate the stresses and the principal stretches.

-- Biswajit

It's an old topic.

Shunlai.Zang — Sun, 24 Aug 2008 09:05:30 -0400

Just as open source vs. closed source

But I think sharing knowledges is a good thing.

Shunlai

UMAT for Shape Memory Alloys

msimsek — Wed, 20 Aug 2008 12:40:21 -0400

Hi,

I am an M.Sc. mechanical engineering student and I am trying to model super elastic property of shape memory alloys in ABAQUS. I am new to ABAQUS and trying to learn it by reading the tutorials. It seems I have to use UMAT but I dont know how to use it or how to create a subroutine for my case. If anybody helps, makes contribution it would be appreciated.

Look forward to getting some responses.

Thanks

Miray

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?

Scientific Computing and

Donald X. Chen — Sun, 03 Aug 2008 00:42:39 -0400

Scientific Computing and computing Scientifically.

Excavation is a typical problem of geotechnical engineering. I didn't use Abaqus to carry out the FE analysis of thus problems. But I did some with other softwares. It seems that you are using the associated plastic flow rule (i.e. friction angle = dilation angle).

If unloaded Mohr-Coloumb soil with zero cohesion subjects to tension, the convergence problem may occure.

Good Luck!

X. Chen