Otto-Von-Guericke Universitat Magdeburg

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Ansys Lab. Report, Advance A 3-D thermal problem solution process in Ansys

AHMAD GOHARI

Supervisor: Mr. Alfakheri

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Ansys Mechanical (APDL)

Introduction:

ANSYS is a general purpose finite element modeling package for numerically solving a wide variety of

mechanical problems, used widely in industry to simulate the response of a physical system to structural

loading, and thermal and electromagnetic effects. ANSYS uses the finite-element method to solve the

underlying governing equations and the associated problem-specific boundary conditions.

ANSYS is a general purpose software, used to simulate interactions of all disciplines of physics,

structural, vibration, fluid dynamics, heat transfer and electromagnetic for engineers.

So ANSYS, which enables to simulate tests or working conditions, enables to test in virtual environment

before manufacturing prototypes of products. Furthermore, determining and improving weak points,

computing life and foreseeing probable problems are possible by 3D simulations in virtual environment.

ANSYS software with its modular structure as seen in the table below gives an opportunity for taking

only needed features. ANSYS can work integrated with other used engineering software on desktop by

adding CAD and FEA connection modules.

ANSYS can import CAD data and also enables to build geometry with its "preprocessing" abilities.

Similarly in the same preprocessor, finite element model (a.k.a. mesh) which is required for computation

is generated. After defining loadings and carrying out analyses, results can be viewed as numerical and

graphical.

ANSYS can carry out advanced engineering analyses quickly, safely and practically by its variety of

contact algorithms, time based loading features and nonlinear material models.

Problem:

Solve this problem and show the temperature gradient. Draw the temperature gradient on a diagram as

well for the required point.

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Preparing Geometry (Modeling) and Meshing:

First we open Ansys application. We choose the Jobname and then location of file which we want to

save our operation then press Run.

1st step: we should define our problem field. In this case choose Thermal.

The path of choosing operation field:

- Preferences> Thermal> ok

2nd step: We want to choose our element type. In this problem our Model is 3-Dimentional so we

choose “ Brick 8node 70”. For 3-D models this kind of element type is better.

The path of choosing element type:

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- Preprocessor>element type>add-edit-delete>add>Solid> Brick 8node 70>ok>close

3rd step: Now we want to define thermal conductivity, Specific heat and density of our model.

The path of defining thermal conductivity:

Preprocessor>material property>material model>Thermal>conductivity>isotropic>KXX (Define 54 for

this problem)

Preprocessor>material property>material model>Thermal>Specific heat>0.47

Preprocessor>material property>material model>Thermal>density>7833

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Now I want to create the model:

First we can create the profile of the model and then extrude the profile around the proper axis.

1st Step:

Preprocessor>modeling>create>area>rectangle>by two corners

X=0 / Y=0 / Width=0.15 / Height=0.05

X=0 / Y=0 / Width=0.05 / Height=0.30

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For extruding along an axis, the area should be added:

2nd Step:

Preprocessor>modeling>operate>Booleans>add>area

No I want to define the axis which we’ll extrude the area around it:

3rd Step:

Preprocessor>create>keypoints>in active CS

X=-0.1 / Y=0

X=-0.1 / Y=0.3

Now the area and axis are ready, we’ll extrude the area along the defined axis:

4th Step:

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Preprocessor>modeling>operate>extrude>area>along axis>180 degree

Now for creating the hole, we’ll create a cylinder and then subtract it from the model:

5th Step:

Preprocessor>modeling>create>volume>cylinder>solid cylinder

X=-0.1 / Y=0.2 / Length=1

And then we’ll move the cylinder to cross the model properly:

6th Step:

Preprocessor>modeling>move/modify>volume>Z=-0.5

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Now, we’ll subtract the cylinder from the model:

7th Step:

Preprocessor>operate>Boolean>subtract>volume

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Meshing:

We can mesh the model now with this order:

1st Step:

Preprocessor>Meshing>Mesh tool> mesh

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Boundary conditions and solutions:

As it’s said in the problem, we want to define the temperature of inside area to 90 degree Celsius

1st Step:

Solution>define loads>apply>Thermal>Temperature>on area>90 degree

Now, we want to define the convection and bulk temperature of outside area of the model, with this

order:

2nd Step:

Solution>define loads>apply>Thermal>convection>on area>

h=20 degree Celsius

Tb=20 degree Celsius

Now we should define that our solution is transient with this order:

3rd Step:

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Solution>analysis type>new analysis>transient>full>ok

Now we want to define the time gaps between our transient solution, with this order:

4th Step:

Solution>load step opts>Time frequencies>time-time steps

10

10/100

Stepped

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Everything is ready and we can solve the problem with this order:

1st Step:

Solution>Solve>Current LS

We can see the contour plot now with this order:

General postproc>contour plot

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For drawing the gradient diagram we should follow this order:

Time Histproc>

Then we choose the proper point and click the draw bottom.

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Then as it’s shown in the picture, we’ll choose a point and draw the temperature gradient, the diagram

would be like this:

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