Assignment 2

OBJECTIVES:

• To edit the given engine file by calculating the run time, with 20 animation steps and observe the stress wave propagation.
• Carry out 3D meshing on the given components and also check for element quality for the 2D meshed models.

PROCEDURE:

RADIOSS

1. Calculate the speed of sound in the material with the formula ).Observe the units system followed in the starter file. (g mm ms). The calculated speed comes out to be 5188.7 mm/ms.
2. Find the time taken for the sound to propagate through the crash tube, set this as run time.

D/c=1000/5188.7=0.192 ms.

3. Calculate the animation time step as: Run time/ No. of animation steps desired.
4. Save the engine file in a local drive and then run Radioss. Set number of threads as “-nt 4” for completing the job faster.
5. Look for the combined animation file .h3d in the same location and open in hyperview. Select contour and von-misses stress and observe the stress wave.

3D MESHING

1. Open the file housing.hm. Because of the shape of the component we have to go for tetra elements.
2. Select the hub as current component and do 2D auto-meshing on it with tria elements. Set element size as 5 mm.
3. Then open 3D mesh and set parameters such as tet collapse at 0.15 and the press tetramesh, select the elements and mesh.
4. Then set cover as current component and press 3D meshing. In 3D meshing select tetra and then select volume tetra. Set the element parameters such as element size as 5mm and tet collapse at 0.15 and then mesh.
5. After meshing go to tools, select check elements and check the quality of elements.
6. Next, open the file armbracket.hm. Select base as current component and hide others. Now create a 2D mesh on upper surface with only quad elements with 10mm target element size.
7. Go to 3D mesh, select elements offset and solid layers. Select the elements to be offset and along geometry with number of layers. Hit enter to create the mesh.
8. Select the arm curve as the current component and mask the hexa elements. Select spin elements, select the elements create the base point for the curve and then hit spin+ or spin- to generate the mesh.
9. Select arm straight as current component. Go to tools-faces-find faces for the curved component. These form the source elements.
10. Create the destination element on destination surface with the similar mesh density as source. Set alignment with the three nodes and mesh. Delete the faces.
11. Then select boss as the current component. Select the top face and do 2D meshing ensuring proper mesh connectivity with the arm straight component.
12. Create a node on destination surface to complete the node path using project.
13. Select solid map, select the elements to drag, destination geometry, along geometry and press solids to generate the mesh. Delete the 2D elements.
14. Switch on all components to see the final mesh.

1D MESHING

1. Open the 1D elements file and practice making various 1D elements like rigids, springs, bar, beam etc. on the given geometry.

2D ELEMENT QUALITY CHECK

1. Open the 2D meshed files. Select tools-check elements and set the element quality criteria as: Imax 7 mm, Imin 3.5 mm, target element size 5mm, aspect 5, skew 60, jacobian 0.5, warpage 15, tria angles 20-120 and quad angles 40-140.
2. Check for each of the parameters in the meshed model and correct the failed elements accordingly by remeshing.

IMAGES:

RESULTS AND CONCLUSION:

Thus through this exercise learnt 3D meshing techniques with TETRA and HEXA(BRICK) elements, became aware of element quality checks and their recommended parameters, 1D element formulation. Also, carried out first simulation on Radioss and observed stress wave propagation after carrying out relevant hand calculations and changing them in the engine file.