Assignment 2-RADIOSS Engine File Editing & 3D Meshing Challenge

OBJECTIVE :

• Check Material Property of the Rail component and Calculate the following:
• 1) speed of sound in steel rail.
• 2) time taken for a shock wave to travel from one end of the rail to the other.
• 3) time for sound to travel length of rail.
• Edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during impact.
• Set the frequency of animation output to a time that will give 20 animation steps
• Change /print -10.

• 3d meshing tetra mesh and hex mesh

  • Repeat class examples and, maintain the quality.
  • Target tet size=5mm,hex size=10mm,tet collapse=0.15.

Solution:

1) Check Material Property of the Rail component.

• Inorder to check the material property of the defined Rail Component, FIRST_RUN_0000.rad file is opened.

The file gives value of,

Youngs Modulus, E = 210000

Density, Rho = 0.0078

To Calculate:

1) Speed of sound in Steel Rail:

Speed of sound in solids,

C_solid = √( Youngs Modulus / Density of solid)

C_solid = √(210000/0.0078) = 5188.745 m/s

Therefore, Speed of sound in Steel Rail = 5188.745 mm/ms

2) time taken for a shock wave to travel from one end of the rail to the other:

For elemental time step, we have :

∆t_e = L / C_solid

Given, Length of rail = 1000mm

Speed of sound, C_solid = 5188.745mm/ms

Time Step, ∆t_e = 1000 / 5188.745 = 0.1927248 ms

Therefore, time taken for a shock wave to travel from one end of the rail to the other = 0.19272ms

3) time for sound to travel length of rail:

Time taken for sound to travel length of rail = time taken for shock wave to travel length of rail

Therefore, time for sound to travel length of rail = 0.19272ms

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

Given Engine File:

In the default engine file, the termination time is set as 60ms.

Editing the default run time to time taken for the sound to travel the length of the rail = 0.1927248ms

3) Set the frequency of animation output to a time that will give 20 animation steps

We have Total time step, ∆t_e = 0.1927248 ms

Inorder to have 20 animation steps, total time step should be divided by 20.

Therefore, Frequency = 0.1927248/20 = 0.009636ms

Editing the default frequency in the engine file:

4) Change /print -10:

Value of /Print - 10 is changed to /Print/ - 200

5) 3d meshing tetra mesh and hex mesh:

Quality Criteria :

• Target tet size=5mm,hex size=10mm,tet collapse=0.15.

Model 1 - Arm Bracket - Hex Meshing:

Procedure:

• Import:
• Thie given Arm Bracket model is imported using import geometry option.

• Meshing:
• Starting from the base component, 2-D elements are created using automesh option uder 2-D tab with hex size of 10 mm.

• To obtain 3-D hex mesh, elem offset option under 3-D tab is used.
• The 2-D elements created are selected, thickness, no. of layers and along geometry is selcted under solid layers option.

• To mesh the arm_curve part, spin option under 3-D tab is used after masking the hex8 elements created.

• Spin elems option is selected, with angle = 90deg and on spin = 20 (layers) and 3-D elements are created.

• To mesh on the arm_Straight part, which is having a taper, linear solids option under 3-D tab is used.
• To use linear solids, 2-D elements should be present at the start face of the part. Hence faces option under tools tab is used.
• The 3-D elements on the arm_curve is selected and face is created.

• In case of linear solids option, there should be start elements as well as destination elements. So destination elements are created using automesh option under 2-D tab with node orientation matching with the start elements.

• Creating the 3-D mesh with linear solids option.

• The remaining part to be mesged is the boss.

• Meshing the top surface with 2-D elements using automesh option.

• After 2-D elements are created, a node which is normal to the present element nodes are created on the bottom surface of the boss.

• Now using solid map option under 3-D tab to obtain 3-D hex mesh on the boss.
• The elemenst created by solid map is stored under new collector(solid map) which is moved to boss using organize option.

Conclusion:

Hence 3-D hexa meshing of the arm bracket is carried out by using various options (elem offset, Linear solid, Solid Map, Spin)under 3-D tab

Model 2 - Housing - Tetra Meshing:

Procedure:

• Import:
• Thie given Housing model is imported using import geometry option.

• Meshing:
• 2 parts of the Housing are meshed seperately. Initially the surfaces are meshed using automesh option under the 2-D tab.
• Element size is set as 5mm and mesh type as trias.

• To convert the created 2-D tria elements to tetra mesh, tetra mesh option under 3-D tab is used.
• The elements are selected and tetramesh parameters (min. tet size and tet collapse) are defined and meshed.

• Some of the elements are masked to check whether tetra elemenrs are created throughout the part.
• The created tetramesh elements is saved under different collector which is moved to the parent collector using organize option.
• Hence the cover part of the housing is meshed using tetramesh option.

• Now to mesh the hub part, volume tetra option under tetramesh tool is used.
• Under volume tetra, 2-D type, 3-D type, element size is defined. Also the surfs is selected.

• Hence the hub part of the housing is also meshed using volume mesh option and mesh is obtained as shown above
• Tet collapse check is also used to check whether all the elements fall under the given quality criteria checked using check elems option

Conclusion:

• Given housing model is meshed using 2 different 3-D meshing techniques , tetramesh & Volume tetra and the elements are within the given tet collapse criteria