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ABAQUS ERROR RADIATION PROBLEM

ABAQUS ERROR RADIATION PROBLEM

ABAQUS ERROR RADIATION PROBLEM

(OP)
I am runnin simulations for heat transfer analysis counting conduction, when I add the effect of surface radiation to environment with *radiate or *sradiate , I am getting the error message:

***WARNING: Temperature at 1 nodes has fallen below absolute zero. Increment
             will be attempted again with a new time increment. The nodes have
             been identified in node set WarnNodeTempBelowZeroStep2Inc45.

               CONVERGENCE CHECKS FOR EQUILIBRIUM ITERATION     1


 AVERAGE HEAT FLUX                   1.78       TIME AVG. HEAT FLUX    2.75    
 LARGEST RESIDUAL HEAT FLUX         7.470E-07   AT NODE      60122   DOF 11
 LARGEST INCREMENT OF TEMP.         3.352E-02   AT NODE      60122   DOF 11
 LARGEST CORRECTION TO TEMP.       -6.868E-05   AT NODE      60122   DOF 11
          THE HEAT FLUX EQUILIBRIUM EQUATIONS HAVE CONVERGED

 MAXIMUM NON-PRESCRIBED INCREMENT IN TEMPERATURE IS   3.352E-02
          TIME INCREMENT MAY NOW INCREASE TO    6.371E-05

 ***WARNING: TEMPERATURE AT NODE 3 (-1.50112E-03) HAS FALLEN BELOW ABSOLUTE
             ZERO (0.0000).  INCREMENT WILL BE ATTEMPTED AGAIN WITH A TIME
             INCREMENT OF 1.59273E-05
  

 ***ERROR: TOO MANY ATTEMPTS MADE FOR THIS INCREMENT

  

Did anyone experience that problem, please help me?

My initiol condition is 373 K at each node, so negative temperature values at nodes are nonsense.

  

Thanks

  

Emrecan Soylemez
 

RE: ABAQUS ERROR RADIATION PROBLEM

It would be very unusual for convergence not to be obtained. I'd check your model constants, such as stefan boltzmann's constant to make sure you have the right units. I'd also check the node location for the warning message and the boundary conditions there about.  

corus

RE: ABAQUS ERROR RADIATION PROBLEM

(OP)
All units are already checked. And nodes are well located. Any other opinion?

Thanks

RE: ABAQUS ERROR RADIATION PROBLEM

Do you have temperature dependent properties that may be incorrect?

corus

RE: ABAQUS ERROR RADIATION PROBLEM

(OP)
The properties are temperature dependent but they were checked.

RE: ABAQUS ERROR RADIATION PROBLEM

If the change in temperature is too severe then you can get divergence in some methods, though I'm not sure what method Abaqus uses to solve for radiation. You can improve convergence by setting the initial temperature of the body  to the same order you expect the converged temperature to be at. Otherwise try a transient analysis so that the temperature change is relatively small for each step.  

corus

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