hi
i am divakar .here are the line details:
line:5 L gr B,nitrogen line,DT:60 degC,DP:165 psig,
total length:1500 meters.total number of nodes:5250(10 increment)
5 meters underground;

I am facing a problem that at 66DegC CAESAR II is making infinite iterations(not stoping,not compiling).
but it is compiling 50 Deg C.
plaese ...suggest me what to do.
thank you
divakar

Hello Divakar,

You will find that most problems with convergence are associated with nonlinearities. Look for sliding supports (restraints) for which you have specified a friction factor. Perhaps one of your sliding supports will have no load on it at the 66 degree C temperature whereas at the 50 degree temperature it WILL have a load on it. If so, try deleting the friction factor and running it again.

These issues have been discussed here at the Caesar II discussion forum for years and there is a large body of knowledge to be discovered by using the search function that is provided at the top of the forum page. Good luck with your analyses.

Regards, John

Press F2 to find if the non-convergence is due to "old state open new state closed" or "sliding error" type. If it is case one, then the non linearity is the gap in restarint, if it is of type 2, the non linear effect is Friction.

For type 1, see if gap can be removed, for type 2, see if Friction factor can be removed( I am personally against changing the default friction stiffness).Sometimes you can get both 1 and 2 type.

This is based on "how to solve the problem in hand" type cookbook solution. I want you to throughly undertand the science behind this non -convergence.

Regards

Dear Divarka,
try to use in the static load case editor the option "Load Case Options" and edit the column "Friction Multiplier". Here you can set the friction effect to "0" for all supports by inputting the factor 0. You'll get a solution without friction but in most cases you'll get a solution. studying these reults you should be able to modify a few support conditions to get solutions including friction.
regards

Several good hints have already been provided.

I believe friction causes most of these convergence problems but I prefer to turn a +Y or two into a Y or remove gaps on a few guides to settle the model down. You should find that these linear simplifications get you output and once you have output, you can examine the "error" in these adjustments by evaluating resulting restraint reactions or nodal displacements. My guess is that these "errors" are usually small and that's why the system had trouble converging.

Use the [Search] option at the upper right of this page. You'll find a number of posts on this subject.

Here is a summary of what goes on in the iteration scheme, and why convergence problems occur.
http://www.coade.com/ubbthreads/ubbthrea...h=true#Post4548