Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Ansys Time-History analysis problem

Status
Not open for further replies.

YamaT

Structural
Jun 17, 2010
6
Hello

I wanted to ask if anyone can give an advice on what I am doing wrong, I am quite new to this. It is a problem with Ansys Time-history post processor.

What I have done so far is that I have applied 6 different section forces on an offshore jacket construction, moments and forces about 3 axis (modelled in ANSYS classic in 3D using BEAM and MASS elements). These forces (calculated using NREL's FAST program) are varying in time and are represented as time series over a period of 1500 seconds, so I had to import them as TABLEs. The problem is when trying to display eg. von Mises stress variation in ANY element+node as a function of time using Time-history post processor. The time axis is displayed correctly (min value 0 max value 1500 seconds). Problem is with the stress part. It displays stress as constant value during this period (min 80 max 80). This is impossible since all loads are time varying.

Here are the applied settings:

In Analysis Type > Solution Controls > Basic > I have selected "All solution items" and as frequency "Write every substep" is selected

Also in Load Step Output > Solution Printout > All items and every substep is selected ...

I get constant stress every time and I have tried to "play" with the settings and nothing.

Please advice

Thanks
 
Replies continue below

Recommended for you

Hi,

I think you have to do a load step analysis using transient analysis. I will upload a tutorial to this. Hope u can get a good idea from that how to do transient analysis with load steps.

Hope this will help you
Cheers
 
 http://files.engineering.com/getfile.aspx?folder=831efb01-785d-47a2-90f7-56bf21d57585&file=transient_load_steps_tutorial_v81.pdf
Thank you very much!

All it needed was analysis type. Even though I had time dependent forces it was not sufficient/correct to select static analysis.

I changed the analysis type and followed the tutorial you posted and now I get exactly what I want. Thanks again. Much appreciated.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor