Hello All,

We have Ansys and Femap/NX Nastran licenses in use, our main FE tool is Femap/Nastran where most of the in-house programming (such as fatigue calculation procedure) is done.

We use Ansys mainly for product development work where the parametric APDL models are quite handy to analyse alternative designs.

However, for the fatigue calculation, I would need to transfer some Ansys models (Shell 181/Beam188) to Nastran; I was thinking to try to do this through Femap as it is a ‘general purpose’ preprocessor (to my knowledge); but it seems the *.db or *.cbd formats are not supported by Femap.

Iges file can be read in but it only contains the geometry.

Has anyone come across a way to do such a model transfer?

BR / Marko Aalto

Deltamarin Ltd

Hello!  My memory is foggy since it's been years since someone else mentioned Femap to me.  But in that conversation, I think the person insinuated there was Femap connectivity available for Workbench.  I don't recall if they shared any of the details or even if my recollection is on track.  But I do know a colleague and I had a discussion about running Workbench Mechanical models and post-processing the fatigue in Femap.  So with that said, perhaps search the web to see if Femap offers a Workbench connector.

—Matt

-----Original Message-----
From: Marko Aalto via Xansys xansys-temp@list.xansys.org
Sent: Friday, June 6, 2025 7:29 AM
To: xansys-temp@list.xansys.org
Cc: marko.aalto@deltamarin.com
Subject: [Xansys] Convert ANSYS model through FEMAP tp NX Nastran

Hello All,

We have Ansys and Femap/NX Nastran licenses in use, our main FE tool is Femap/Nastran where most of the in-house programming (such as fatigue calculation procedure) is done.

We use Ansys mainly for product development work where the parametric APDL models are quite handy to analyse alternative designs.

However, for the fatigue calculation, I would need to transfer some Ansys models (Shell 181/Beam188) to Nastran; I was thinking to try to do this through Femap as it is a ‘general purpose’ preprocessor (to my knowledge); but it seems the *.db or *.cbd formats are not supported by Femap.

Iges file can be read in but it only contains the geometry.

Has anyone come across a way to do such a model transfer?

BR / Marko Aalto

Deltamarin Ltd

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Hi Marko, we do this transfer from Ansys to Femap quite regularly. The cdb-file is the medium. If the cdb-file is written from workbench we read in that file in APDL and rewrite it to get rid of the workbench specific things that Femap comments as an error. The newer Ansys versions (ongoing from 2021r1) unfortunately write a string "UNBL" in the cdb that Femap does not understand. A search and replace of the cdb-file are necessary. We use a command line tool for this. Google for "rpl.exe" or use any editor. First replace "EN,UNBL" then "N,UNBL" and then "UNBL". I think the need for this order is obvious.

cdwrite,db,export_a_%ans_rev%_unblocked,cdb,,,,unblocked ! must be unblocked for FEMAP

*if,ans_rev,ge,211,then

/syp,rpl,' EN,UNBL EN,R5.5 export_a_%ans_rev%_unblocked.cdb'
/syp,rpl,' N,UNBL  N,R5.3  export_a_%ans_rev%_unblocked.cdb'
/syp,rpl,' UNBL    R5.0    export_a_%ans_rev%_unblocked.cdb'

*endif

Mit freundlichen Grüßen / Kind regards

i.A. Peter Eisenträger
Senior Development Engineer CAE

OHB Digital Connect GmbH
Weberstraße 21
55130 Mainz / Germany

Tel. +49-6131-2777-106
Fax. +49-6131-2777-205
eMail:     Peter.Eisentraeger@ohb.de
Internet: www.ohb-digital.de

Geschäftsführer: Dennis Winkelmann, Dr. Dieter Birreck, Fabrice Scheid
Sitz der Gesellschaft: Bremen
Registergericht: Amtsgericht Bremen, HRB 20042

-----Ursprüngliche Nachricht-----
Von: Marko Aalto via Xansys xansys-temp@list.xansys.org
Gesendet: Freitag, 6. Juni 2025 13:29
An: xansys-temp@list.xansys.org
Cc: marko.aalto@deltamarin.com
Betreff: [Xansys] Convert ANSYS model through FEMAP tp NX Nastran

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Hello All,

We have Ansys and Femap/NX Nastran licenses in use, our main FE tool is Femap/Nastran where most of the in-house programming (such as fatigue calculation procedure) is done.

We use Ansys mainly for product development work where the parametric APDL models are quite handy to analyse alternative designs.

However, for the fatigue calculation, I would need to transfer some Ansys models (Shell 181/Beam188) to Nastran; I was thinking to try to do this through Femap as it is a ‘general purpose’ preprocessor (to my knowledge); but it seems the *.db or *.cbd formats are not supported by Femap.

Iges file can be read in but it only contains the geometry.

Has anyone come across a way to do such a model transfer?

BR / Marko Aalto

Deltamarin Ltd

Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.

Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list

Thank you Peter and Matthew,

I tried out the commands of the Peter’s message - however did not really get the result I wanted in Femap, still quite a few error messages even after trying to clean up the input.

Then, I just went for the ‘standard’ way and created a .cdb file Test2.cdb:

/PREP7

CDOPT,IGES

CDWRITE,ALL,'Test2','cdb',,'file','iges'

Much to my surprise, this file reads into Femap almost perfectly!

There was only one error message because the line “N,UNBL,LOC,      -1,” was two times in the .cdb file (consecutive lines) but after removing the duplicate there were no errors any more.

Everything (except the line loads) seems to be transferred, even beam sections are the same as in the original ANSYS model.

Femap:

File -> Import -> Analysis Model -> Select ‘ANSYS’ -> Select Test2.cdb -> Open

Still need to check the loads, but perhaps quickest is just to delete all loads in Femap and create new load cases. Anyways, only one LC is contained in the .cdb file.

Regards,

Marko Aalto, M.Sc.
Project Discipline Manager, Hull FEA & Rule calculations

Deltamarin Ltd, Postikatu 2, FI-20250 Turku, Finland, www.deltamarin.com