Assignment 5-RADIOSS Interfaces & Study of Effect of Notches Challenge

Objective:

Create the mesh for bumper assembly,mesh size should be 6mm.

1. Run the crash tube model as it is.
2. Change the Inacti=6 and run.
3. Create the type 11 contact and run.
4. Remove both notches and remove boundary condition on rigid body node then run.
5. Create a new notch in the middle ,select the whole section and run.
6. Create a new notch with nodes only from opposing 2 faces and run.

• Plot RWALL forces ,contact forces,internal energy and Create TH/PART for all parts and compare results for all cases.
• Comment on:
• Why there is a change in the internal energies.
• How does the notch affect the results?

Case 1

The model is run without making any changes:

We get to know that notch causes stress concentration and buckling of tube starts from notch area. Deformation starts from notch and lower part buckles first and after that upper part starts buckling. Max stressvalue comes out to be 0.6984.

From the Rigid wall force curve it can be seen that it peaks at around 25 ms which means that around this time the tube has been crush and is no longer absorbing any force and because of that the rigid wall forces are increasing.

Same can be interpreted from Internal energy curve as the crushing begins the internal energy increases till around 26 ms, at this point the tube has absorbed maximum energy and further energy is transmitted to the wall.

The kinetic energy continuously decreases as expected and at the end slightly increases due to rebound of crush tube.

Contact energy also goes maximum at around 25 milisec.

Hourglass energy remains zero throughout.

Case 2: Change the Inacti=6 and run.

Changing the inacti value in hypercrash though it does not change the max von mises streess generating in the tube.

Rigid wall forces remain unchanged and from the Rigid wall force curve it can be seen that it peaks at around 25 ms which means that around this time the tube has been crush and is no longer absorbing any force and because of that the rigid wall forces are increasing.

Same can be interpreted from Internal energy curve as the crushing begins the internal energy increases till around 26 ms, at this point the tube has absorbed maximum energy and further energy is transmitted to the wall.

Case 3: Create the type 11 contact and run.

After 25 ms the rebound of the tube occurs due to the normal reaction force from the rigid wall.

In TYPE11 contact the contact energy falls to zero at 28 ms, thus it can be stated that there is very less self edge contact involved. This causes almost no change in rwall forces.

The energy curves are similr to case 1 and case 2.

Case 5 - Create a new notch in the middle, select the whole section and run

In this all 4 surface buldge outside as all faces have notch created on them.

In this case case the KE is completely converted in IE. other energy curves are similar to TYPE 11 contact plots.

Case 6: Create a new notch with nodes only from opposing 2 faces and run.

The buckling effect in this case is lesser as compared to case 5 and due to this reason the rigidwall forces are also reduced in this case. In this case only 2 surface buldge outside as compared to all 4 in case 5.

The buckling effect in this case is lesser as compared to case 5 and due to this reason the rigidwall forces are also reduced in this case.