3D meshing and Radioss Introduction

3D meshing and Radioss Introduction

Objectives:

1. Check the material properties of the rail component and calculate the speed of sound in steel rail

2. The length of the rail is about 1000 mm, calculate the time takes for a shock wave to travel from one end of the rail to the other.

3. Time for sound to travel length of rail.

4.Edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during impact -this will require a termination time equal to the time it takes for the sound to travel the length of the rail(set on/RUN card).

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

7. 3d meshing tetra mesh and hex mesh. Maintain the quality of Target Tet size=5mm, hex size=10mm, Tet collapse=0.15

Procedure:

1. Check the material properties of the rail component and calculate the speed of sound in steel rail?

• Open the file FIRST_RUN_0000.rad which is starter input file, here we will get all required material data regarding rail component.
• Young’s Modula’s E= 210000 N/mm2
• Density Rho= 0.0078 g/mm3
• Now formula to calculate speed of sound is =√E/ρ= √210000/0.0078=5188.75mm/ms

1. The length of the rail is about 1000 mm. Calculate the time takes for a shock wave to travel from one end of the rail to the other.

=1000/5188.75=0.1927246ms

3.Time for sound to travel length of rail= 0.1927246ms

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

=0.1927246/20= 0.0096373ms

4&6.Edit the engine file so that the stress wave can be monitored

Fig- Above image shows after editing engine file.

7.3d meshing tetra mesh and hex mesh. Maintain the quality of Target Tet size=5mm, hex size=10mm, Tet collapse=0.15

1. 3D Meshing of Arm Bracket:

• Import the model in hypermesh, check for any geometric errors and correct it if any.

Step 1- Meshing of base with Element size of 10.

• To generate 3D meshing, first we have to generate 2D mesh on upper layer of base.
• Now to generate 3D mesh, go to 3D> elem offset> select 2D element> select Surface along> enter no. of layers> enter total thickness (check by measuring node distance by F4) > offset+.

Fig- Above fig shows 3D mesh generation of base.

Step 2- Meshing of Arm Curve.

• First determine the radius of curve and centre point of curve.
• Then go to 3D> spin> spin elems and select the 2D elements on base and put 90 degree as angle and on spin 25 divisions.
• Select centre of spin and define axis of rotation and hit on spin+.

Fig- Above fig shows meshing of Arm Curve

Step 3- Meshing of Arm Straight.

• First make sure on both side there should be same no. of elements.
• Now we have to create face to perform 3D liner solid meshing, to do so go to Tools> Faces > select arm curve> find faces. After finding faces go to 3D> linear solid> select from elements & to elements and give same alignments points on both faces and then click on solids.

Fig- Above fig shows meshing of Arm straight

Step 4- Meshing of Boss Component.

• First select the upper face of boss and perform 2D meshing on it.
• Then match the no of elements of top surface of boss with arm straight so that there will be no mismatch.
• Now create a duplicate node in line with arms straight vertical profile to give a line of direction to 3D meshing, it can be done by going to Tools> Project> to surface > select node > duplicate it> select to surface> click project.
• Now go to 3D > solid map > elems to drag> select source geom to none & select destination geometry> select node path> click mesh

Fig- Above fig shows meshing of Boss

Step 5- Deleting of faces.

• Now delete the faces created while modelling by got to tools> faces> Select component> click delete faces.

Fig- Above fig shows final model

1. 3D meshing of Housing (Hub)

Step 1- 2D meshing

• Import the model in hypermesh, check for any geometric errors and correct it if any.
• Now go to 2d> automesh> Select the surface> set element size to 5> only trais> click mesh

Step 2- 3D meshing

• Go to 3D> in tetramesh parameters set Tet collapse to 0.15> in tetramesh> Select all elements> click on mesh
• Go to tools> check elements> set Tet collapse to 0.15 and check for no of elements failing for.

Fig- above Fig Shows 3D meshing of Hub

3D meshing of Housing (Cover)

Step 1- 3D meshing of housing cover

• Go to 3D> in tetramesh parameters set Tet collapse to 0.15> in volume tetra> Select surface> set tetra size to 5> click on mesh

Fig- Above fig shows meshing of cover.

3. Check no. of elements failing for Tet collapse

• Go to tools> check elements> set Tet collapse to 0.15 and check for no of elements failing for.

Fig- above Fig shows no. of elements failing for Tet collapse

Learning-

• Learned how to calculate time taken by sound to travel the rail.
• Learned how to calculate time step.
• Learned how to calculate time frequency.
• Learned where to find material properties and how to edit engine file.
• Learned how performed 3D meshing with different methods.
• Learned which unit system is followed in radioss.

Tools learned-

• Solid Map, Linear Solid, Elem Offset, Tetra mesh, Spin, Faces, Project, Check Elements

Conclusion-

By checking the properties of steel rail component in starter file we calculated time taken by shock wave to travel rail component =0.1927ms & Frequency of animation= 0.0096ms. And successfully meshed housing with zero Tet collapse.

Gdrive Link- https://drive.google.com/open?id=1x85aVDczWgCexenGckUZnvBrn2HP-NSn