Experiment 10

Aim: Exercise on FEM using

Objective: Find the displacements, stresses and strains at each node.

This bracket is to be built from a 20 mm thick steel plate. A figure of the plate is shown

below.

Figure 10.1 Metal Bracket

All dimensions are in mm.

Young’s modulus, 200 Gpa

Poission’s ratio, 0.3

This plate will be fixed at the two small holes on the left and have a load applied to the larger

hole on the right.

Preprocessing: Defining the Problem

Give the 2D Bracket example a Title

Utility Menu > File > Change Title

Form Geometry

Create the main rectangular shape

The main rectangular shape has a width of 80 mm, a height of 100mm and the bottom left

corner is located at coordinates (0,0)

Now we are going to enter code into the 'command line'.

BLC4, XCORNER, YCORNER, WIDTH, HEIGHT

BLC4, X coord (bottom left), Y coord (bottom left), width, height

Therefore, the command line for this rectangle is BLC4,0,0,80,100

Create the circular end on the right hand side

The center of the circle is located at (80,50) and has a radius of 50 mm

The following code is used to create a circular area:

CYL4, XCENTER, YCENTER, RAD1

CYL4, X coord for the center, Y coord for the center, radius

Therefore, the command line for this circle is CYL4,80,50,50

Now create a second and third circle for the left hand side using the following dimensions:

parameter circle 2 circle 3

XCENTER 0 0

YCENTER 20 80

RADIUS 20 20

Create a rectangle on the left hand end to fill the gap between the two small circles.

XCORNER -20

YCORNER 20

WIDTH 20

HEIGHT 60

Your screen should now look like the following...

Boolean Operations - Addition

To perform the Boolean operation, from the Preprocessor menu select:

Modelling > Operate > Booleans > Add > Areas

In the 'Add Areas' window, click on 'Pick All' You should now have the following model:

Create the Bolt Holes

We now want to remove the bolt holes from this plate.

Create the three circles with the parameters given below:

parameter circle 1 circle 2 circle 3

WP X 80 0 0

WP Y 50 20 80

radius 30 10 10

Now select

Preprocessor > Modeling > Operate > Booleans > Subtract > Areas

Select the base areas from which to subract (the large plate that was created)

Next select the three circles that we created. Click on the three circles that you created and

click 'OK'. Now following will appear:

Define the Type of Element

PLANE82 will be used for this example

Preprocessor > Element Type > Add/Edit/Delete

Use the 'Options...' button to get a plane stress element with thickness

Under the Extra Element Output K5 select nodal stress.

Define Geometric Contants

Preprocessor > Real Constants > Add/Edit/Delete

Enter a thickness of 20mm.

Preprocessor > Material Props > Material Library > Structural > Linear > Elastic > Isotropic

Enter the following when prompted:

EX 200000

PRXY 0.3

Mesh Size

Preprocessor > Meshing > Size Cntrls > Manual Size > Areas > All Areas

Select an element edge length of 5. Again, we will need to make sure the model has

converged.

Preprocessor > Meshing > Mesh > Areas > Free and select the area when prompted

Solution Phase: Assigning Loads and Solving

Define Analysis Type

'Solution' > 'New Analysis' and select 'Static'.

Now, the plate is fixed at both of the smaller holes on the left hand side.

Solution > Define Loads > Apply > Structural > Displacement > On Nodes

Instead of selecting one node at a time, you have the option of creating a box, polygon, or

circle of which all the nodes in that area will be selected. For this case, select 'circle' as shown

in the window below. (You may want to zoom in to select the points Utility Menu / PlotCtrls

/ Pan, Zoom, Rotate...) Click at the center of the bolt hole and drag the circle out so that it

touches all of the nodes on the border of the hole.

Click on 'Apply' in the 'Apply U,ROT on Lines' window and constrain all DOF's in the

'Apply U,ROT on Nodes' window.

Repeat for the second bolt hole.

Apply Loads

As shown in the diagram, there is a single vertical load of 1000N, at the bottom of the large

bolt hole. Apply this force to the respective keypoints Solution > Define Loads > Apply >

Structural > Force/Moment > On Keypoints Select a force in the y direction of -1000)

The applied loads and constraints should now appear as shown below.

Solving the System

Solution > Solve > Current LS

Post-Processing: Viewing the Results

We can have a look at the deflected shape and the stress contours

Deformation

General Postproc > Plot Results > Def + undeformed to view both the deformed and the

undeformed object.

The graphic should be similar to the following

Observe the locations of deflection. Ensure that the deflection at the bolt hole is indeed 0.

Deflection

To plot the nodal deflections use

General Postproc > Plot Results > Contour Plot > Nodal Solution then select DOF Solution -

USUM in the window.

Stresses

General Postproc > Plot Results > Nodal Solution... Then select von Mises Stress in the

window.

You can list the von Mises stresses to verify the results at certain nodes

General Postproc > List Results. Select Stress, Principals SPRIN

Experiment 11

Aim: Exercise on Thermal conduction problem

The Simple Conduction Example is constrained as shown in the following figure. Thermal

conductivity (k) of the material is 10 W/m*C and the block is assumed to be infinitely long.

Figure 11.1 Thermal heat conduction problem

Preprocessing: Defining the Problem

Give example a Title

Open preprocessor menu

ANSYS Main Menu > Preprocessor /PREP7

Create geometry

Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners > X=0, Y=0,

Width=1, Height=1

BLC4,0,0,1,1

Define the Type of Element

Preprocessor > Element Type > Add/Edit/Delete... > click 'Add' > Select Thermal Mass

Solid, Quad 4Node 55

ET,1,PLANE55

For this example, we will use PLANE55 (Thermal Solid, Quad 4node 55). This element has 4

nodes and a single DOF (temperature) at each node. PLANE55 can only be used for 2

dimensional steady-state or transient thermal analysis.

Element Material Properties

Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic >

KXX = 10 (Thermal conductivity)

MP,KXX,1,10

Mesh Size

Preprocessor > Meshing > Size Cntrls > ManualSize > Areas > All Areas > 0.05

AESIZE,ALL,0.05

Mesh

Preprocessor > Meshing > Mesh > Areas > Free > Pick All

AMESH,ALL

Solution Phase: Assigning Loads and Solving

Define Analysis Type

Solution > Analysis Type > New Analysis > Steady-State

ANTYPE,0

Apply Constraints

For thermal problems, constraints can be in the form of Temperature, Heat Flow, Convection,

Heat Flux, Heat Generation, or Radiation. In this example, all 4 sides of the block have fixed

temperatures.

Solution > Define Loads > Apply

Note that all of the -Structural- options cannot be selected. This is due to the type of element

(PLANE55) selected.

Thermal > Temperature > On Nodes

Click the Box option (shown below) and draw a box around the nodes on the top line.

The following window will appear:

Fill the window in as shown to constrain the side to a constant temperature of 500

Using the same method, constrain the remaining 3 sides to a constant value of 100

Orange triangles in the graphics window indicate the temperature contraints.

Solve the System

Solution > Solve > Current LS

SOLVE

Postprocessing: Viewing the Results

Plot Temperature

General Postproc > Plot Results > Contour Plot > Nodal Solu ... > DOF solution,

Temperature TEMP

Note that due to the manner in which the boundary conditions were applied, the top corners

are held at a temperature of 100. Recall that the nodes on the top of the plate were

constrained first, followed by the side and bottom constraints. The top corner nodes were

therefore first constrained at 500C, then 'overwritten' when the side constraints were applied.

Decreasing the mesh size can minimize this effect; however, one must be aware of the

limitations in the results at the corners.

Experiment 12

Aim: Exercise on FEM of Fluid flow problem

Objective: Study the fluid flow behavior through a pipe.

Air Properties:

Density = 1.23 kg/m3

, Viscosity = 1.79 8*e-5 Ns/m.

The air velocity over the cylinder is going 24.6 m/s.

1. Main Menu>Preferences

In the Preferences for GUI Filtering dialog box, click on the box next to FLOTRAN

CFD so that a tick mark appears in the box. Click OK

2. Specify element type:

Main Menu > Preprocessor >Element type > Add/Edit/Delete > Add….

Pick Flotron CFD and select 2D FLOTRON 141 click OK

3. Specify Material Properties

Main Menu > Preprocessor > Material Props > Material Models

In the material models available frame of the defined material model behavior window,

double-click on CFD, Density and Viscosity.

Enter 1.23 for density.

Enter 1.79 e-5 for Viscosity.

Go to preprocessor > Flotron setup > fluid properties.

On the box, shown below, make sure the first two input fields read AIR-SI, and then click on

OK. Another box will appear. Click OK to accept default values.

4. Create Geometry

Preprocessor > Modelling > Create > areas > Rectangle > By Dimensions

X = 0, 2

Y = 0, 0.5

Preprocessor > Modelling > Create > areas > Circle > Solid Circle

X = 0.5

Y = 0

Radius = 0.125

Now, subtract solid circle from the rectangular area

Preprocessor > Modelling > operate > Boolean > Subtract

First select rectangular area Click OK now select solid Circle click OK.

5. Create Mesh

Main Menu > Preprocessor > Meshing > MeshTool

In Mesh tool select size control > lines > set

Select all lines and enter the element edge length 0.02 and click OK

Meshing > Mesh > Area > Free > OK

6. Apply boundary conditions

Preprocessor > loads > define loads >Apply > Fluid CFD > velocity > On Lines

Select front vertical And top horizontal lines. In pop up window apply 0.005 in “VX load

value” and 0 in “VY Load Value”

Similarly Apply velocity on cylinder edges taking Values 0 for both VX & VY.

By this the cylinder boundary will become fully constrained

Preprocessor > loads > define loads >Apply > Fluid CFD > velocity > On Lines

Since we taken the problem of symmetry, we have to apply velocity of common face lines in

Y direction to be 0.

Apply Pressure on the back vertical line taking value 0. it will fulfill the atm. conditions.

Preprocessor > loads > define loads >Apply > Fluid CFD > Pressure > On Lines

7. Solution

Giving iterations to the problem

The no. of iterations are depends on analyst while doing the analysis. In our problem we’ve

taken no .of iterations as 1000.To do this in the Ansys main menu follow the steps.

Solution > FLOTRAN SETUP > Execution control

In pop up window fill 1000 in “Global Iterations” keep remaining as it is.

Click OK.

Solution > solve > Current LS

Click OK

Solution > Run FLOTRAN

8. Postprocess the result

General postpro > Read Results > last Set.

Then go to General Postpro > plot Results > Contour Plot > Nodal Solution > DOF Solution

> Fluid Velocity

General PostProc > path Operations > Define Path > By Nodes

Click on nodes of cylinder to select them.

Click Ok

General PostProc > Path Operations > Map Onto Path

In pop up window select as shown

Click OK.

General PostProc > Path Operations > Plot Path Item > On Graph

Exit > Save Everything > OK