LS Dyna

[SimonH1977]

I am currently working on the dissertation for my Structural Engineering MSc and I have been asked to perform the analysis section of the project in LS-Dyna. I am analyzing the effects of blast loads on steel structures and decided that I would focus mt attentions on transmission towers. I have never operated LS-Dyna and was hoping to be able to model the tower in SAP2000 and then export the file in Dyna, saving myself valuable modelling time as I have only 6 weeks to complete the project. If I get the project completed early I can always spend a bit of time learning more about ls-prepost processor. I have used SAP before for previous projects and was able to model the tower today. However, although I am no dinosaur when it comes to computers, I am certainly no expert when it comes to the different file types that the models can be saved in. After looking at the two software's, I observed that they both support IGES files and quickly exported a basic tower model from SAP200 into Dyna and the export was successful. This where my problem began, when I modeled a more complicated tower and exported the IGES file from SAP to Dyna, the geometry of the tower was messed up. The tower is modeled using Angle steel elements.

I am currently researching how best to approach this problem and what my options are. However, I was hoping to acquire some expert input from here and maybe some guidance on where to focus my attentions when dealing with my problem.

Any assistance would be appreciated

Regards

Simon

 

[missil3]

Hey,

The iges translator in lsprepost is not very good. Just to clear a few things, have you unselected the "Import unblanked shapes" when importing in lsprepost ? You might have to use the latest lsprepost 3.2 / 4.0 for this (not sure which exactly).

Other than that if you have access to hypermesh, you can mesh the geometry in hypermesh much better than lsprepost. Then import the mesh in lsprepost and setup the keywords.

lsprepost tutorials are available at :

http://www.lstc.com/lspp/

in case you haven't gone through yet.

I am not sure about SAP2000 but it seems it can do meshing ? if so you can export the mesh from SAP2000 in Nastran formation (bulk.dat) and import that into LSprepost

 

[SimonH1977]

Missil3

Thank you for replying to my thread. I am running the 3.2 version as there was no link to download the 4.0 version of ls prepost and I have unselected the 'Import unblanked shapes' option when importing into prepost. The university is quite limited in terms of software and the only civil/structural packages that they have are Midas, SAP2000 and CAD. I did look at the Nastran file type but SAP2000 only seems to be able to import it rather than being able to export this file type. I am currently working on altering my Theses as I have discovered a better subject to investigate.

Again, thank you for replying

Simon