Tuesday, 20 September 2011

Adding Thermal Boundary Conditions in a Structural Analysis in ANSYS

Thermal boundary conditions are sometime needed in a ANSYS structural analysis. An example of a time when this is required is when an FSI analysis is being setup using ANSYS and CFX where stresses in the structural components due to applied loads and thermal loads are important. The following command snippet can be put into a ANSYS structural analysis to apply thermal loads (assuming that the element types have been modified to accept a temperature degree of freedom).

In each command snippet everything should be left untouched with the exception of  text in between <>. For example <reference Temp> should be replaced with 293 to set the reference temperature in the boundary conditions. The < and > should be removed when a variable, named selection, or value is entered.

All text that comes after ! is commented out. Therefore only commands after /SOLU are implemented in ansys. The rest before that is for documentation and information.

Temperature Boundary Condition

!   Commands inserted into this file will be executed just prior to the Ansys SOLVE command.
!   These commands may supersede command settings set by Workbench.

!   Active UNIT system in Workbench when this object was created:  Metric (m, kg, N, s, V, A)

!   Specifies a temperature boundary condition for a transient run in a Ansys structural sim.
!   Format is:
!   TREF, <reference Temp>
!   cmsel, s, <named selection to apply convection BC to>
!   d, all, CONV, <Temp>
!   allsel
!   trnopt, full

/SOLU
TREF, <reference temperature>
cmsel, s, <named sel>
d, all, TEMP, <Temp>
allsel
trnopt, full

Convection Boundary Condition

!   Commands inserted into this file will be executed just prior to the Ansys SOLVE command.
!   These commands may supersede command settings set by Workbench.

!   Active UNIT system in Workbench when this object was created:  Metric (m, kg, N, s, V, A)

!   Specifies a convection boundary condition for a transient run in a Ansys structural sim.
!   Format is:
!   TREF, <reference Temp>
!   cmsel, s, <named selection to apply convection BC to>
!   sf, all, CONV, <heat transfer coefficient>, <Bulk temp>
!   allsel
!   trnopt, full

/SOLU
TREF, <reference Temp>
cmsel, s, <named sel>
sf, all, CONV, <heat transfer coefficient>, <Bulk temp>
allsel
trnopt, full

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