Transcript Workshop 7: Thermal steady state analysis of a composite slab

University of Puerto Rico at Mayagüez
Department of Mechanical Engineering
Workshop 7:
Thermal Steady State
Analysis of a
Composite Slab
Modified by (2008): Dr. Vijay K. Goyal
Associate Professor, Department of Mechanical Engineering
University of Puerto Rico at Mayagüez
Thanks to UPRM students enrolled in INME 4058
sections 2006-08
Scope

The purpose of this workshop is to
demonstrate ANSYS capabilities in solving
thermal problems. For this we will solve the
steady state temperature field of a composite
slab with a hole using the following
prescribed geometry and boundary
conditions:
Geometry and Boundary Conditions
Starting ANSYS

From your desktop:
Click on: START > All Programs >
ANSYS >
ANSYS Product Launcher.

Here we will set our Working Directory
and the Graphics Manager
Working Directory


This is the
10.0 ANSYS
Product Launcher
main window.
Select the Working
Directory and type
the name of work
shop on Job Name.
Graphics Setup

Click the button:
Customization/Preferences.

On the item of Use custom
memory settings type 128
on Total Workspace (MB):
and type 64 on
Database (MB):

Then click the Run
bottom.
* This setup applies to computers running under 512 MB of RAM
ANSYS GUI Overview

This is ANSYS’s Graphical User Interface window.
GUI Filtering

In order to maximize your workspace to meet
your needs. Let’s filter out the GUI (Graphical
User Interphase).

Click on Preferences > Choose on GUI Filtering:
Thermal > OK.
GUI Filtering
1
2
Element Definition

For ANSYS to properly analyze the problem,
we must choose well the appropriate
element. We will choose Element Type Quad
4node 55:
Element Definition
Element Type:
1. On Main Menu window, click Preprocessor > Element Type > Add/Edit/Delete
2. Click Add… on The Element Types Window
1
2
Element Definition
3. On the Library of Element Type window select Quad 4node 55 > click
OK > click Close on the Element Type window
3
plane55 will produce either quadrilateral or triangular elements for thermal analysis
Material Properties

Now lets assign the thermal conductivity (k)
for the two materials of this problem:


Material 1 – KXX = 20
Material 2 – KXX = 50
Material Properties
1. On the Main Menu Window select Preprocessor > Material Props > Material
Model.
2. On the Material Model Behavior window select Material Model Number 1 >
Thermal > Conductivity > Isotropic
3. On the Conductivity for Material Number 1 enter 20 for Thermal Conductivity
KXX > click OK
2
3
Material Properties
4. To add a second material:

Click on the tab: Material > New Model > Define Material ID insert 2.
Material Properties
Click
on: Thermal > Conductivity > Isotropic > then on KXX insert the
thermal conductivity of the second material (KXX = 50) > OK and close
the Material window.
Geometry

The strategy to produce the geometry is to
create two rectangles (material 1 & 2) and
remove a hole from the material 1
Geometry
1. To create first rectangle, on the Main Menu Window select Preprocessor >
Modeling > Create > Areas > Rectangle > By 2 Corners
2. On the Rectangle by 2 corners window enter WP X = 0 > WP Y = 0 > Width =
0.05 > Height = 0.05 > Click Apply
Note that all dimensions
were converted to meters
1
2
Geometry
3. To create the second rectangle repeat the process 2, using the following
values:
WP X = .05
WP Y = 0
Width = .1
Height = .05
3
Geometry
4. To create the circle, on the Main Menu Window select Preprocessor >
Modeling > Create > Areas > Circle > Solid Circle
5. On the Solid Circular Area Window enter WP X = .025 > WP Y = .025 >
Radius = .01 > Click OK
4
5
Geometry
6. To create the hole select Preprocessor > Modeling > Operate > Booleans >
Subtract > Areas
7. Click on the left rectangle > Click Ok on the Subtract Areas window
8. Click on the circle > Click OK again on the Subtract Areas window
7
6
8
Geometry
9. To join the two rectangles, select Preprocessing > Modeling > Operate >
Booleans > Glue > Area
10. On the Glue Areas window select Pick All \ OK
9
10
Now ANSYS know that the two rectangles are in contact, and make one big composite slab.
Meshing

To make the finite element analysis we must
first divide the object into small elements, this
is called meshing.
Meshing
1. On the Main Menu window, select Preprocessor > Meshing > Mesh Tool
2. On the Mesh Tool window Click on Smart Size > Select 5 > Select Mesh:
Areas > Click on Set under Element Attributes
3. On the Meshing Attributes Window select Element Type number: 1 Plane 55
> Material number: 1 > click OK > Mesh > Click on the left rectangle
2
3
1
Meshing
4. A screen like this will appear.
4
To view the two rectangles again go to Plot \ Areas
Meshing
5. Repeat steps 1 through 3 selecting Material Number: 2 on the Meshing
Attributes Window and Clicking on the right rectangle after selecting Mesh.
5
Meshing
6. To see the mesh go to PlotCtrls \ Numbering
7. On the Plot Numbering Controls Window got to Elem/Attrib numbering \ select
Material numbers \ Click OK
7
This should give you a color plot showing the areas and elements. Each element
contains a number which refers to the material numbers we just set for each
piece. The different material types are also denoted by the different colors.
Boundary Conditions

Now we will apply the given boundary
conditions for each side of the slab.





Left Wall @ T = 200
Right Wall @ T = 50
Lower Wall is adiabatic
Upper Wall has a h = 150 @ T = 25
Hole has a flux of q = 100
Boundary Conditions (Temperature)
1. On ANSYS Main Menu Window select Preprocessing > Loads > Define Loads
> Apply > Thermal > Temperatures > On Nodes
2. On the Apply TEMP on Nodes window Click on Box and draw a box around
the left edge of the model to pick these nodes.
2
2
1
Boundary Conditions (Temperature)
3. On the New Apply TEMP on Nodes window select DOFs to be constrained:
Temp \ Apply as: Constant value \ Load Temp Value: 200
3
4. Repeat above procedure to apply the temperature boundary condition
on the right boundary with a temperature of 50.
Boundary Conditions (HT Coefficient)
1. On ANSYS Main Menu Window select Preprocessing > Loads > Define Loads
> Apply > Thermal > Convection > On Nodes
2. On the Apply CONV on Nodes window Click on Box and draw a box around
the top edge of the model to pick the nodes along the top edge.
1
2
Boundary Conditions (HT Coefficient)
3. On the New Apply CONV on Nodes window select VALI Film coefficient\
enter h of 150 \ VAL2I Bulk Temperature \ 25 \ Click OK
3
Boundary Conditions (Heat Flux)
1. On ANSYS Main Menu Window select Preprocessing > Loads > Define
Loads > Apply > Thermal > Heat Flux > On Nodes
2. On the Apply HFLUX on Nodes window Click on Circle and draw a circle that
catches the nodes around the hole.
1
2
Boundary Conditions (Heat Flux)
3. On the New Apply HFLUX on Nodes window select VALUE Load HFLUX
value\ enter 100 \ Click OK
3
Note: All geometry boundaries are adiabatic by default in ANSYS. So if you wish
to apply symmetry or zero heat flux boundary conditions at any face of your model
you have to do nothing to that face. We do not do any thing to the bottom edge of
our model because it is an adiabatic surface by default.
Display Settings
4. To see the boundary conditions on
the model go to PlotCtrls \ Symbols
5. On Symbols windows go to Surface
Load Symbols\ select Convect
FilmCoef \ Show pres and convect
as \ select Arrows \ Click OK
6. Repeat step 5 selecting Heat Flux
instead of Convect FilmCoef
5
FEM Solution

We are ready to start with the finite element
analysis and obtain the temperature
distribution across the slab.
FEM Solution
1. On ANSYS Main Menu window select Solution > Solve > Current LS
1
Temperature Distribution
1. On ANSYS Main Menu Window select General Postproc > Plot Results >
Vector Plot > Predefined
2. On the Vector Plot of Predefined Vectors window Click OK
2