Assignment 2

Objective: A. To Calculate various parameters from given Engine Input file

B. To edit Engine output file to get desired output

C. To Hexa mesh the given component

D. To Check the 2D mesh quality of meshed component and create 3D mesh as per given criteria.

Procedure:

A.

1. By checking the material properties from the Engine Input file, we get following values:

E = 210000MPa

`rho` = 0.0078 g/mm3

Thus to get speed of sound in Steel we use the formula

`v= √(E/ρ)`

Substituting the above values we get

v = 5188.75 m/s

2. Time taken for shock wave to travel the length of the rail

`T=L/v`

Here v is the speed of shockwave in steel, which is the same as speed of sound in steel

L = 1000 mm i.e 1 m, v = 5188.75 m/s

Substituting in above equation we get,

T = 0.0001927 s i.e 0.1927 ms

3. Time taken for sound to travel length of rail

Its the same as time taken for shock wave to travel length of rail,

so T = 0.1927 ms, as calculated above.

B.

1. Edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during impact

For this we need to set the runtime as the time taken for the stress wave to travel through the component, which we have calculated above.

Thus we substitute the value in the Engine Input file as shown:

2. Set the frequency of animation output to a time that will give 20 animation steps(/ANIM/DT)

For 20 animation steps we divide the Termination time by the number of animation steps required

which gives us an animation step every 0.009635 ms

We input this in the Engine Input file as shown:

3. Change /print -10

We change it to /PRINT -100 as shown:

C. To Hexamesh the given component:

1. Open the component in Hyperworks in Optistruct module

2. Mesh the base using 5mm quad elements, ensuring there are no trias

3. Use Line Drag comand to create a 3D mesh using the above generated 2D mesh

4. Now create a node at the center of the Curved portion using the Nodes-Arc center option.

Use this node to spin the 2D elements at the center as shown:

The result is as shown:

5. Now create 2D mesh on the other side of the straight portion. Ensure the number of nodes match exactly to the number on the other side, for all edges.

We will use this as teh destination eleements while using the Linear solid command

Go to Tools-Faces and create faces out of the recently created 3D elements. This is needed to select source surface for the comand.

Now using Linear solid comand we generate a 3D mesh as shown:

6. Now we 2D mesh elements on the boss:

7. Now we use Solid map to create the 3D mesh of the boss using nodelist and lines as constraints.

8. Now we check for equivalence at the intersecting nodes and correct them using increasing values of tolerance so that the nodes are perfectly matching.

Then we delete the unwanted 2D elements.

The final model looks as shown.

D. To Check the 2D mesh quality of meshed component and create 3D mesh as per given criteria.

1. Open the given model in Hyperworks and check the mesh using Element check after applying the given criteria:

As we can see there are a lot of failing elements.

We delete the mesh and recreate it as per given criteria. Cleanup tools are used to repair the mesh and smoothen it.

2. The mesh is completely repaired of any failing elements as shown:

3. The 3D mesh is generated from it using the Tetramesh option. In tetramesh parameters, Tet collapse is set at 0.15

After the mesh is generated, it is checked for tet collapse.

4. For the other component we use Volume tetra option to create teh 3D mesh.

The geometry is first cleanep up and small/unnecessary edges are toggled off

5. Volume tetra option is used to create the 3D mesh as shown:

Result:

A. Required parameters are calculated from given Starter input deck.

B. Engine input file is edited as required.

C. The given model is meshed using Hexa elements

D. The given mesh is checked and repaired for failing elements, and 3D meshing is carried out.