Wednesday, November 12, 2008


There are some queries asking if this blog is officialy related to Abaqus. To make things clear and to avoid confusion, I decided to write this post.

Abaqus is a trademark owned by Abaqus Inc. This blog is in no way affilated to Abaqus, and therefore UNOFFICIAL.

The blog is intended to discuss the various problems faced by users like me and to get different perspectives to the problem. Often one is struck with a single viewpoint and finds it difficult to solve the problem. The blog is intended to get more viewpoints. The original plan was to start a forum, but I started this blog, because it is easier.

As I mentioned in About Blog, this page is not merely for writing about Abaqus Software, but also about Science in General.

If you have any thoughts about the whole blog, do feel free to comment.

Monday, November 10, 2008

Difference in Results Between Various Versions and OSs

Julian Hallai asks...
I have been running jobs in different machines with different OS and different abaqus versions. The same input file gives reasonably different outputs. The machines were:
1) IBM Unix Machine with abaqus 6.3
2) Linux Machine with abaqus 6.7
3) Windows Machine with abaqus 6.7
So I got different results with the same version of abaqus in two different machines (with different OS) and also different results with different versions in Unix/Linux.

This doesn't happen to all input files. It has happened to about 50% of the cases (total 20 jobs).

I should also write that the material's engineering stress-strain curve has one part that's softening.

Any thoughts on that?

Thank you so much

Answer :
From Version 6.3 to 6.7 Abaqus has changed a lot, especially in the contact formulation. Please check if the input files, which exhibit remarkable difference between versions, have some specific contact definitions. These contact definitions often exhibit such differences between the versions. Material model implementation is another area where discrepancies may occur. But it is very difficult to ascertain that without looking into the exact case.

Non-Convergence of the input file between versions is very common and people at Abaqus themselves accept this and suggest to read the documentation before using any keyword. The release notes in documentation for every version are a good source of reference to check what all had been changed in the new version.

Difference in results from one OS to another for the same version is defintely a bug. You should contact abaqus support to notify the bug.

Saturday, November 8, 2008

Assembling parts from Different Models

Basavaraj asks..
i have imported two inp files in abaqus now i want to assemble
how to do assemble two different inp files in abaqus GUI?

Answer :
What do you mean by assembling? Do you want to assemble the parts from the input files together?
In CAE ( Version 6.8), after you have imported the inp files, you will get 2 models. Then goto
Model->Copy Objects...
There you can copy different objects ( in your case, the orphan mesh parts, sections, materials etc..) in a single model. Then you can assemble the parts together.

Beam Elements with Solid Elements

Jason asks....
Can we use beam element and solid element in one model ? And how to deal with the joint section ?

Answer :
Yes, it is possible to use beam elements with solid elements. If modelled so, the nodes at which the beam and solid elements join, will have additional DOFs. ( e.g. 6 DOFs if 3D Beams are used. Please note that normally nodes of solid elements will have only 3 DOFs)

Abaqus Online Tutorials

In addition to the basic tutorials found in at simulia website, I found the following resources helpful for abaqus beginners.

Abaqus Tutorial Slideshow at as video

Abaqus Tutorial Slideshow at as PPT

Abaqus Tutorial at Brown University

Chapter 11 of "A First Course in Finite Elements" by Jacob Fish, Ted Belytschko ( Google books)

The above mentioned book from another website

Another tutorial from iMechanica

Please note that I have collected all this information just by googling. The links are credited to the respective authors. If some links are not working, please try other links or you google yourself.