DSC algorithm

[Anonymous]

 Hello,

When studying the vibrations of a structure in Robot, it suggests you to use the DSC algorithm for the calculations. 

In certain cases though, when you apply this method in the calculation, the bending moment diagrams are not the same as before. 

For exemple the static calculus gives me a 6200 kNm maximum bending moment. 

When I divide the bars into multiple segments, the maximum bending moment is given 6300 (basically the same).

When I introduce the DSC algorithm though, the maximum bending moment in my structure jumps to 7400 kNm. 

Could you please explain me the reason for this effect ? 

Thank you in advance.

Kind regards,

Boris Sachansky

[Artur.Kosakowski · Accepted solution]

Hi Boris,

Could you attach the model and both your hand calculations and screen capture showing what to look at exactly? 

[Anonymous]

Hello,


You can find attached to this mail the 3 separate models that allow to
compare the results when introducing :


- division of bars

- DSC algorithm


I am sorry, I can't seem to upload any more files and the Internet proxies
at work are blocking basically all useful internet sites...


I am at your disposal for any further clarification you may need.
​
basic model with divided bars.PNG

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basic model with divided bars.rtd

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basic model.PNG

​​
basic model.rtd

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DSC algorithm.PNG

​​
DSC algorithm.rtd

​

[Anonymous]

Hello,


You can find attached to this mail the 3 separate models that allow to
compare the results when introducing :


- division of bars

- DSC algorithm


I am sorry, I can't seem to upload any more files and the Internet proxies
at work are blocking basically all useful internet sites...


I am at your disposal for any further clarification you may need.
​
basic model with divided bars.PNG

​​
basic model with divided bars.rtd

​​
basic model.PNG

​​
basic model.rtd

​​
DSC algorithm.PNG

​​
DSC algorithm.rtd

​

[Artur.Kosakowski]

Hi Boris,

Try to upload the files using one of these services and post the link to download them

https://forums.autodesk.com/t5/robot-structural-analysis-forum/sending-bigger-files/td-p/3795062

[Anonymous]

Artur, 

I've just recieved the Wetransfer link, which I use for bigger files. It took more time than usual... 

https://wetransfer.com/downloads/c2aa6089557b0678e9b5f964108f785620170620153803/fd8053

I hope it works out for you. 

Regards,

Boris Sachansky

[Anonymous]

Hi Artur,

I used Wetransfer to upload the files. Hope it works for you. The link is : 

https://wetransfer.com/downloads/c2aa6089557b0678e9b5f964108f785620170620153803/fd8053

Normally I replied you  2 days ago but apparently it didn't work out or something... sorry for the delay...

[Artur.Kosakowski]

Hi @Anonymous

My assumption is that the difference is caused by slightly different cladding load distribution (I made the test for self weight only for no DSC + no bar division model vs. DSC + no bar division model for self -weight only with all rigid links and claddings deleted and obtained the same results). This is expected when you add additional nodes but apparently the calculation nodes generated when you use DSC algorithm has got the influence as well. 

In addition check the values of the maximal RX rotations - you may want to block RX in definition of releases.

I hope this helps.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.