Steady State Heat Transfer Problem

[Anonymous]

I am using Simulation Mechanical 2012.

I have a beam and I have applied a temperature to each end of the beam to look at temperature distribution along the beam.

Under certain conditions, my results will show temperatures far outside the range of my 2 initial applied temperatures. My initial temperatures are 90F and 110F and my results can show between -130F and 190F.

It gets into this mode when I increase my total number of elements by either changing the size of my mesh or increasing the length of my beam.  As best that I can tell, I have this problem above 100,000 elements.

Help would be appreciated.

[Anonymous]

There was a similar problem fixed in an incoming service pack. Can you post your model to check?

[Anonymous]

Has the service pack already been released?

I cannot upload a file that big so I have attached a few screenshots.

Is there another method to post the fem file?

Summary Log:

Autodesk (R) Simulation Steady-State Heat Transfer
Version 2012.01.00.0017-W64/X64 15-Jun-2011
Copyright (c) 2011, Autodesk, Inc. All rights reserved.

      DATE: JULY 5, 2012                  
      TIME: 09:06 AM
      Input Model: H:\FEA\Plain Beam\Rod.ds_data\1\ds


           PROGRAM VERSION: 201201000017
           ALG.DLL VERSION: 201201000017
     AlgConfig.DLL VERSION: 201201000017
      Agsdb_AR.DLL VERSION: 201201000017
      AMGSolve.DLL VERSION: 201201000017
      AlgSolve.DLL VERSION: 201201000017
 

 **** Model Unit System Settings:
      --------------------------------------------
       Unit System              : English (in)
       Force                    : lbf
       Length                   : in
       Time                     : s
       Temperature (Absolute)   : deg F (R)
       Thermal Energy           : in*lbf
       Voltage                  : V
       Current                  : A
       Electrical Resistance    : ohm
       Mass                     : lbf*s^2/in
      --------------------------------------------

 
 Thermal
                                                  
 **** CONTROL INFORMATION                         
                                                  
      number of node points                    =    182701
      number of element types                  =    2
      analysis type code                       =    10
      equations per block                      =    0
      bandwidth minimization flag              =    0

 **** PHYSICAL CONSTANTS USED WHEN APPLICABLE 

      The Stefan-Boltzmann Constant      =  3.083E-11
      Temperature Increment to Absolute  =  4.597E+02
                                                  
 **** NON-LINEAR ITERATION CONTROL PARAMETERS     
 
      Nonlinear control option           =          OFF
      Convergence criterion              =          2
      Maximum number of iterations       =          15
      Interval for monitoring            =          5
      Corrective tolerance               =          1.0000E-03
      Relative tolerance                 =          1.0000E-03
      Relaxation parameter               =          1.0000E+00
 
 **** PRINT OF NODAL DATA SUPPRESSED              
 
 **** PRINT OF EQUATION NUMBERS SUPPRESSED        

 **** FLUID FLOW CONVECTION IS NOT INCLUDED IN THIS MODEL.

 **** HARD DISK FILE SIZE INFORMATION FOR PROCESSOR:

      Available hard disk space on H drive =  38276.797 megabytes

                                                  
 **** LOAD CASE MULTIPLIERS                       
                                                  
      Boundary temperature multiplier       1.000
      Convection multiplier                 1.000
      Radiation multiplier                  1.000
      Heat generation multiplier            1.000

 **** AMG SOLVER CONTROL INFORMATION 

      Convergence Tolerance    =   1.000E-06
      Maximum Iteration Number =     1000
      AMG log output level     =       -1
 
 **** Invoking Iterative AMG Solver ...
 **** End solution 
 
 
                                                  
 **** TEMPORARY FILE STORAGE (MEGABYTES)          
      ----------------------------------          
       UNIT NO.  7 :      1.394
       UNIT NO.  8 :      7.710
       UNIT NO.  9 :      0.040
       UNIT NO. 10 :      0.040
       UNIT NO. 11 :    265.467
       UNIT NO. 12 :      0.000
       UNIT NO. 13 :      0.040
       UNIT NO. 14 :      0.000
       UNIT NO. 15 :      0.040
       UNIT NO. 18 :      0.040
       UNIT NO. 65 :      1.394
       UNIT NO. 67 :     85.904

       TOTAL       :     362.070



 **** End of File **** 
 

[John_Holtz · Accepted solution]

Hi,

My guess is that you can get accurate results by reducing the "Stiffness" of the Controlled Temperatures. According to the documentation, the stiffness should be "(2-3 orders of magnitude higher than the conductivity of the materials in your model)".

[Anonymous]

Thank you very much. That seems to have fixed the issue.