Spring 1999, METBD452 - FEA Heat Transfer Applications

Prof. Dave Johnson, dhj1@psu.edu, Penn State - Erie, The Behrend College

ANSYS Radiation Matrix Procedure

1.  In the Preprocessor, build a Thermal Model
	Don't bother defining the emissivity of radiating surfaces as material properties.
	You do that later in the Radiation Matix Utility 

2. "SKIN" the radiating surfaces:
		- in 2D:   with LINK32
		- in 3D:   with SHELL57
	NOTE:  If you have different surface emissivities, assign different 
		material ID numbers to the "skin" elements

	Check the element orientation (ESYS) to verifiy radiating surface
	Check the material ID assignments (NUMBERING) for different surface emissivities.

3.  Decide if you need a "SPACE NODE".  If so, create it and record its node number.

4.  Enter the "Radiation Matrix" processor.

5.  Define the emissivity for each material of the "skin" elements.

6.  Under "Other Settings":
		- define the Stefan-Boltzmann constant (in proper units)
		- pick 2D or 3D model
		- if axisymmetric, set divisions around circumference.
			At least 20 is recommended.
		- enter the "space node" number, if used

7.  Select the nodes and elements of the "skin"

8.  Under "Write Matrix":
		- pick "Hidden" (more expensive on system resources)
			- OR-
		        "Non-Hidden" (can't have blocked/shaded surfaces)
		- usually Matrix Printout is unnecessary
		- give a name for the radiation matrix file

9.  Return to the Preprocessor

10.  Delete/Clear/Unselect the "skin" elements.

11.  Add a new element type, Superelement, MATRIX50
	  Set the Element Options for "radiation substructure"

12.  Set 'Default Attributes' for the new element type ID number.

13.  Create a new element (the radiation superelement) "From a .sub file"

14.  Make sure you use absolute temperatures or define the offset between your temperatures and absolute zero.

15.  Define other loads and boundary conditions on the model.

16.  If needed, apply temperature on the "space node."