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Zero Displacement

Zero Displacement

Zero Displacement

(OP)
Dear all

I wonder have any of you encouter such error:

***ERROR: A ZERO DISPLACEMENT SOLUTION WAS FOUND IN THE FIRST ITERATION OF A
           RIKS STEP. THE ANALYSIS CANNOT PROCEED. THE MOST LIKELY CAUSE IS
           THAT ALL DISPLACEMENT DEGREES-OF-FREEDOM ARE CONSTRAINED TO BE ZERO.

The model is a pipe layed on the seabed where temperature and pipe pressure loading is applied. Prior to the message above, i have the following warnings although my model is still within the elastic range:

***WARNING: THE STRAIN INCREMENT HAS EXCEEDED FIFTY TIMES THE STRAIN TO CAUSE
             FIRST YIELD AT 26368 POINTS

 ***WARNING: THE STRAIN INCREMENT IS SO LARGE THAT THE PROGRAM WILL NOT ATTEMPT
             THE PLASTICITY CALCULATION AT 26368 POINTS
 

 ***NOTE: MATERIAL CALCULATIONS FAILED TO CONVERGE OR WERE NOT ATTEMPTED AT ONE
          OR MORE POINTS. CONVERGENCE IS JUDGED UNLIKELY.

Greatful if any can suggest ways to get around the problem.

Thanks
sgdon

RE: Zero Displacement

Not sure, have never encountered this. Try decimating your data.

Ron

RE: Zero Displacement

Or in your material data is severe mistake (like Young modulus=1e-19) or the first load step is very high. Therefore the program did not converge to a solution, so the strain/stress field remains as at the begining, no strain and no stress (zero). The code believes this situation is due to a  0 field displacement, which obviously is not the case, and send that message (model over-constrained). So check your input data or divide your step in a multiple load cases.

RE: Zero Displacement

(OP)
Thanks. THe material definition is correct. Im really not too sure what the cause but manage to complate the analysis without using riks.

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