🎉Community Raffle - Win $25

An exclusive raffle opportunity for active members like you! Complete your profile, answer questions and get your first accepted badge to enter the raffle.

Join and Win

Why is the definition of TSTEP necessary for Nonlinear Direct Transient Analysis?

cfuser

Dear Support-Team,

I am currently working on a Nonlinear Direct Transient Analysis to be solved with OptiStruct. I have read in a variety of sources that for this kind of problem NLPARM and TSTEP load collectors must be defined. I have also read that some entries made in NLPARM will override entries written into TSTEP. If this is so, why do I have to define a TSTEP load collector in the first place? Further, is my assumption correct that NINC-, DT-settings in NLPARM (also in NLADAPT and NLOUT) refer to time incrementation when performing a Nonliniear Direct Transient Analysis??

I'd be very grateful for your Help!

Cheers!

Find more posts tagged with

English

OptiStruct

Accepted answers

All comments

tinh

They (software developers) don't merge those 2 cards because some features just need one of them.

It is about data organization, i think so.

cfuser

First of all, thanks for your reply tinh!

I understand what you are getting at. Still, I'm not quite clear about one thing. In TSTEP I am defining ' time step parameters for control and intervals at which a solution will be generated and output in transient analysis' (quote from OptiStruct Help-webpage on Bulk Data Entry TSTEP). I understand what the different parameters are meant to do (N, DT, NO and so forth). But when I define them and leave similar parameters in NLPARM blank intentionally to avoid overriding the solver won't stick to the defined parameters. For example, when I define N=1000 and DT=0.001 in TSTEP I would expect to have 1000 increments solved by OptiStruct. The Out-file shows, that a lot less increments are actually solved. Even when I put DIRECT=yes in NLADAPT to specify fixed increments.

Thinking about it, I still have a lot of stuff I am not sure about regarding HyperMesh/OptiStruct.

Maybe somebody can clear things up for me? /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

Rahul Rajan_21763

Please refer the material shared in below post for Nonlinear Direct Transient Analysis.

https://community.altair.com/community?id=community_question&sys_id=5266003a1b2bd0908017dc61ec4bcba1

cfuser

Hello Rahul,

thank you for your reply.

Cheers!