Tuesday, August 12, 2008

Feature matching in Abaqus & Ansys

On occasion I run into features of ABAQUS that would like to see on the ANSYS side. Case in point, my recent post on XANSYS regarding the modal transient dynamic analysis. The problem arises from ANSYS' inability to apply base motion (acceleration in my case) on structures w/ non zero boundary conditions when the modal superposition method is used. Why modal supeposition you'd ask if the the FULL (default) method (TRNOPT) is fully capable of doing what I need ?? Simple, MSUP is the only option that will allow me to save modal coordinates in jobname.jcf that in turn can be used for further number crunching (fatigue or other postprocessing).
My only recourse is to go back to ABAQUS or Use NASTRAN. Ansys seems to be a fully capable program with an arsenal of capabilities spanning many disciplines.
This 'deficiency' made me think that ABAQUS has features that most likely will not make it on the ANSYS side especially now that the development dynamics within ANSYS Inc are pro-Fluent and more or less neutral-ANSYS. Version 12 is not out yet to make the latter argument stonger or weaker so I'm little reserve as far as what goodies are in our stockings fron Santa-Ansys....

I'd like to know what other features of ABAQUS (if an ABAQUS & ANSYS user) you miss when working on the ANSYS side. By the same token, ANSYS has some real big guns like APDL that Abaqus users would like to have instead of learning python for their scripting. {{python is a very powerful language but not as intuitive as APDL in my opinion - Expect flaming about this from hardcore & seasoned python users}}

Sure, the luxury of having dual super number crunchers like ANSYS & Abaqus doesn't put you in the position of thinking 'Hmm, ANSYS/ ABAQUS doesn't have this or that. What if ... "

Well, not everyone is that lucky and has to make do with one code {{what a life !!!}}.

Your thoughts ???


Paris Altidis

9 comments:

Keith_DiRienz said...

Have you considered putting large masses at the points you to specify an acceleration for? Then you can impose forces on those masses to create the accelerations you need.

Paris Altidis said...

parisAKeith,
It appears that even ABAQUS is using the large mass method behind the scene (at least for the secondary bases) to implement the base acceleration excitation. I'm reading the Abaqus manual to see whether the mass calculation is model based or an arbitrarily big number.
I can see the light in the tunnel w/ the LMM.
:{P

Fern Thomassy said...

I never got deep into ABAQUS programming but did some within the *.inp file with some ABAQUS/Explicit runs ... maybe 5-years ago. They had an okay system. On the static structural side of things I haven't missed anything from ABAQUS since the second release with the CONTA17x elements. How could ANSYS go wrong with former ABAQUS developers using their lesson's learned (kind of like breaking your own world record). Keep in mind I cut my FEA-teeth doing surf-surf contact models in the early 90's using ABAQUS and I was a big fan.

The ABAQUS training programs were fantastic in that they didn't shy away from theory at all. I still use the material for reference. I always felt the ANSYS training was more how-to than why-so.

Anonymous said...

having an integrated explicit solver is real plus for ABAQUS plus the fact that you can easily import/export your model between the implicit & explicit solvers. The 'general contact' algorithm in the explicit solver is very good for tricky contact problems if you are not looking for very accurate contact pressures.

pauline26 said...

Abaqus has axial and lateral friction for its contacts, something which ANSYS lacked. So we always used Abaqus for our lateral buckling models.

In the upcoming version 12, ANSYS has finally incorporated axial and lateral friction for its contact elements, which is even better than Abaqus since in Abaqus, you can only put in 4 points but there's no limit in ANSYS.

The Beta 5 of ANSYS 12 that I was testing still had some other bugs and I didnt have time to continue with the testing, but in some sense, ANSYS is listening to its oil and gas customers.

However, in terms of post-processing, plotting stress along a path, Abaqus/CAE still runs circles around ANSYS. Maybe I shouldnt compare A/CAE with ANSYS, but Workbench instead. ANSYS cant plot stress along a path if the elements are composed of line elements. maybe Workbench can do this but line elements are what most O&G companies work with.

orthodan said...

I like the fact that geometry creation and editing are integrated into the Abaqus CAE preprocessor as opposed to the way Design Modeler and Workbench are separate tools with slightly different functionality. CAE has come a long way in the past couple of releases - we no longer need to use Patran for preprocessing Abaqus models.

Anonymous said...

Pre- and Postprocessing in ABAQUS beats the pants off ANSYS/Classic. The Virtual topology - tool is a big help for complex shaped parts, the sketcher for creating user-parts is intuitive and great to use also for users without CAD-experience. Integration of parts of other databases or models in a new project is a copy/paste feature in ABAQUS/CAE.

Also Postprocessing is great. In ABAQUS i can open several results file at the same time and "lock" the displays with each other, say: same view-direction, same scaling. Perfect for comparing results of different designs.

If a implicit model with rubber or too complex contact won't run, just change the load-step to Dynamic / Explicit and mesh the parts with explicit elements, define general contact (works really great) and rerun.

Online and Paperback Documentation in ABAQUS also beats ANSYS. Hardcore theory presented at it's best, so that the user really understands, what is running in the background and knows of the physics behind the problem.

View-cut display is so damn much quicker than the capped/hidden view in ANSYS.

Best Regards,
Markus

Unknown said...

hello,
im doing my ME project on offshore structures using ansys10, i
dono how to give wave loading, i found that element to be used is
pipe59 and i should acivate the data table(tb),but i couldn c data
tables in material properties, is there any proper steps i should do to
c that option and activate it, pls guide me if im wrong too.pls tell me the exact procedure for wave loading

HMC said...

Hi,
what do you mean on 4 points?