Dear Sirs,


sorry about my questions, but I don't have that much experience with Caesar.


Currently I am working on a model of 15 years old pipeline. This pipeline will be modified, but now I am checking as built.

The temperature in the 23m long pipe is 375°C, that’s why the cold spring was used. For dilation 130mm it was 80mm (about 2/3). I made a model in Cadworx, exported it to Ceaser, completed it, made cold spring in a 80mm pipe element (143-146 in apendix) and ran analysis.

http://uloz.to/4692927/case-operation-condition-w-t1-p1-h-cs.avi

The results look ok. Moment on nozzle is half in operation case. But seeing the animation, in static output it looks discontinuous! And a new rigid element has appeared. ?!

Can you please advise on where the error could have occurred? Have I done a mistake in cold spring modeling? Or could this be a graphical error?

And the last question, should be checked Alowable stress for cold spring pipe element or shouldn´t be?


Many thanks for your help and suggestions!



Regards,




2010/4/30 Vladimír Cebo

No idea, pls?

The problem with the graphics (both the static animation and the standard output graphics) is the "cold spring" element between those rigids.

The way the "cut short" works is that CAESAR II applies an axial force large enough to squeeze the two nodes together - effectively making the element length zero.

The problem with the graphical display of the displacements is that typically the deflections are so small that you would never see them on the screen. So a scale factor is applied, to visually increase the perceived deflections. This is causing the nodes in the vicinity of the cold spring element to "visually" move past each other. This isn't happening in the real system.

Thank You very much for your reply!