NeiNastran ease of use

[trainguy]

Hello all.

We need to purchase either NeiNastran or Algor.

We've demo'd Algor 2 yrs ago and it was quite easy and met our needs, esp. the manipulation of solid models, application of loads and boundary conditions.

We have not used NeiNastran since 2002, and this was only manipulating an FE model, no solids. It twas manageable, but not necessarily easy.

Can anyone tell me how easy the latest NeiNastran (with Femap)is to use? We are looking for something that our engineers may not use for a few weeks, then easily pick up.

We specifically do not have full time FE work, so something intuitive will be useful.

We are fully aware of NeiNastran's stellar support.

Any thoughts?

tg

 

[SWComposites]

Manipulating solids in FEMAP is ok, but definitely not great. Not much has changed on the geometry side in FEMAP in the last few years. Definition of loads and boundary conditions is fairly easy. If you need you need to do a lot of manipulation of solid models you should look at the combination of SolidWorks and NEiNastran (NEiWorks). A lot depends on the CAD system you are currently using and what type of models you will be inporting into the FE preprocessor. You should be able to get at least a 1 month fulll capability demo license from Noran; check out the solid model import and manipulating functions before you make a purchase.

 

[jakeline6]

I would say the meshing has improved greatly in FEMAP since 2002 with the release of FEMAP V9.1. There is better handling of bad solid geometry for starters. Also, with NEiNastran V9 you do not need to worry about matching mesh types in assemblies. You can mesh with tets or hex (bricks) or both and use the automatic surface contact to weld them together or add contact. This make it a lot easier to build complex solid models from 3d CAD files since FEMAP will mesh each individual part with out difficultly and the automated surface contact will recognize the contact and weld the parts together. There is a link at the noran knowledge base site (white papers) and it that says it all...

http://www.nenastran.com/newnoran/p...WPAutomated Surface Contact in NEiNastran.pdf

I would have to say this alone is the best feature of V9 for us because it allows us to use solid models which we can build directly from CAD files.

Noran just released a version of NEiWorks which comes with the Solidworks kernel and is a complete FEA package. This may be what you are looking for because it handles solids very well and includes the full NEiNastran solver for about 1/3 what the FEMAP NEiNastran bundle goes for.

I have some limited experience with Algor and do not believe that have automated surface meshing capability. I also know that in performance comparisons I have done with large solid meshes NEiNastran is much faster for both mesh generation and solution time, if that matters.

 

[usafeng]

I think NE is calling the NEiWorks + SolidWorks package NEiFEA. Just saw a press release on this. NE OEMs SolidWorks and bundles that in for a complete package including their solver.

When you demoed Algor, did you do the demo or did they do a web cast for you? We elected to do our own evaluation and were not as impressed with its “ease of use”. The learning curve on FEMAP is steep and you will be happy later when you need to use the advanced meshing options that have not made their way into Algor yet.

We have about 5 people here all using NEiNastran and FEMAP. When we started we were Patran users which is very different that FEMAP. We picked it up in about 3 days and were fully proficient in less than a week without any external training. Questions would come up, we called, got answers, moved on. Never regretted our decision once.

 

[trainguy]

Interesting stuff.

We are a full-fledged Autodesk Inventor office, and as such, we would probably be generating step files for import into whichever package we choose.

It seems counterintuitive to go to NEi Works, given the solidworks component, then.

Any idea how well the contact features stated above will work? We will demo it anyway, but I thought I'd get some more opinions...

tg

 

[jakeline6]

I am not sure if SolidWorks will read in step files but FEMAP will and should interface with Inventor quite well.

The contact works well with assemblies and a tolerance is provided to distinguish between gaps that are intended and tolerances. I am sure there are situations where it will fail but I have not found any yet.

What we do is mesh the entire assembly at once and then add the PARAM, CONTACTGEN, 2 for welded contact. That is it. If you need to specify a larger tolerance than the default there is another PARAM for that.

 

[GBor]

I have some limited experience with Algor and do not believe that have automated surface meshing capability. I also know that in performance comparisons I have done with large solid meshes NEiNastran is much faster for both mesh generation and solution time, if that matters.

Algor does surface meshing, solid meshing, and mid-plane meshing. It has done surfaces and solids since it was a DOS-based program in the early 90's at least (prior to that, I didn't use the program).

Trainguy, what type of analyses are you doing (linear static, non-linear, impact)? I think either of these programs manipulate solid models from Inventor well. I do think Algor handles the meshing more easily, but certain types of analyses are faster in alternate solvers.

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[jakeline6]

GBor,

We are not talking about meshing which I know Algor can do like any other preprocessor. We are talking about automated surface contact where meshed surfaces in contact or near contact are automatically welded using surface contact weld elements. I know FEMAP has added this in their next release but NEiNastran has had it at the element level since V9. Either way it saves a lot of time. As far as I know only ANSYS and NEiNastran have this feature.

 

[GBor]

It does sound like NEiNastran handles this CAD file intimate contact uniquely. Algor does a mesh-matching so that nodes on individual parts within intimate contact "line up" and become coincident. They do not add additional "contact weld elements", but the mesh alignment reacts as though the parts are welded.

 

[jakeline6]

The advantage of using welded contact is that you can easily change it from a pure weld to bi-directional slide or general contact. Once nodes are merged they have to be unzipped in FEMAP if you later want to add contact. In many cases we run linear statics initially and later do nonlinear and switch to welds to general contact. This ability is very handy.

 

[bjprb]

jakeline6-
not sure i understand something you mentioned about Noran-are they adding features/geometry to a cad model to simulate a weld or are they treating the elements in the original drawing differently so as to simulate a weld - i believe algor claims to have several different options when it comes to simulating contact between parts in a linear static analysis such as fully bonding the parts or treating the parts as welded and also allowing for surface-to-surface contact allowing the parts to move independent of each other - on the matter of algor working with inventor-i believe that algor connects to inventor and that there is some level of associtivity between the two packages eliminating the need for igs transfer between cad and fea - perhaps someone else may know if my understanding is accurate

 

[jakeline6]

The contact is done at the element level after the meshing is done. It is actually done in the solver. The preprocessor has manual surface to surface contact and as I understand UGS is adding automated contact to FEMAP. NEiNastran has automated contact on the element level which means you can have it automatically detect and add contact with a single command regardless of the model complexity. Contact means weld, bidirectional slide, rough or general.

 

[trainguy]

One thing I do not understand in some of the above posts:

What is welded contact? Is it a complete merging of the 2 solids over the whole contact surface, or is it just on the edges that would be accessible by a welder, that the FEA user could select...

tg

 

[dmacx]

As I understand it is the complete merging of 2 surfaces but it uses the surrounding stiffness to create a connection that is similar to if the nodes were coincident and merged. The advantage is that the nodes do not need to be coincident which makes for a much nicer looking mesh. You can model actual welded parts using it by limiting which surfaces or element faces are in contact.