Assignment 5

CRUSH TUBE SIMULATION IN HYPERMESH RADIOSS

OBJECTIVES :

To 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.

PROCEDURE :

MESHING

1. Import Bumper_Assembly.hm to Hypermesh under radioss profile.

2. Select the mesh size as 6mm in mesh parameters.

3. Mesh each surfaces using 2D > Automesh ,mixed and maintain connectivity.

4. Shift+F3 is used to eqivalence the nodes and connect them. Nodes are also connected using F3.

5. 1D > Connectors are used to create spot weld and seam adhesive connections to the Bumper Assembly by entering appropriate values as shown..

6. Save the model.

1. CASE 1 :-

1. Open Hypermesh > Radioss userprofile.

2. Open Applications > Hypercrash, set KN mm ms kg unit system.

3. Import the crushtube_0000.rad file. Select all the checkboxes like boundary conditions, rigid wall, properties, parts, contact interfaces without making any changes. Add TH for part in Data History and save.

4. Export the file to case1 folder.

5. Go back to Hypermesh and import the exported .rad file.

6. Analysis > Radioss, save as Case1 and run without making changes to file. View Simulation from Hyperview

7. Create Von Mises Contour from Hyperview.

8. Plot energy graph and Rigid wall forces.

• The Energy graph plotted between internal energy, Total Energy and contact energy is plotted. Internal Energy increases abruptly upto 45000 J after 25 ms of simulation and then stabilizes until it completes. Contact energy is observed only at the crushed stage.
• The rigid wall forces attain peak value of 1400 N during 25-30 ms of simulation.
• The Time for simulation in .out file is 199.52s , energy error is at -4.6% and no mass error and Hourglass error.

B. CASE 2 :-

1. Open Hypermesh > Radioss userprofile.

2. Open Applications > Hypercrash, set KN mm ms kg unit system.

3. Import the crushtube_0000.rad file. Select all the checkboxes like boundary conditions, rigid wall, properties, parts, contact interfaces change Type 7 inacti=6. Add TH for part in Data History and save.

4. Export the file to case2 folder.

5. Go back to Hypermesh and import the exported .rad file.

6. Analysis > Radioss, save as Case2 and run file.

7. Plot Energy graph and rigid wall forces.

• The Energy graph plotted between internal energy, Total Energy and contact energy is plotted. Internal Energy increases abruptly upto 45000 J after 25 ms of simulation and then stabilizes until it completes. Contact energy is observed only at the crushed stage.
• The rigid wall forces attain peak value of 1400 N during 25-30 ms of simulation.
• The Time for simulation in .out file is 211.61s , energy error is at -4.6% and no mass error and Hourglass error.

C. CASE 3 :-

1. Open Hypermesh > Radioss userprofile.

2. Open Applications > Hypercrash, set KN mm ms kg unit system.

3. Import the crushtube_0000.rad file. Select all the checkboxes like boundary conditions, rigid wall, properties, parts, contact interfaces change Type 11. Add TH for part in Data History and save.

4. Export the file to case3 folder.

5. Go back to Hypermesh and import the exported .rad file.

6. Analysis > Radioss, save as Case3 and run file.

7. Plot the energy graph and rigid wall graph.

• The Energy graph plotted between internal energy, Total Energy and contact energy is plotted. Internal Energy increases abruptly upto 45000 J after 25 ms of simulation and then stabilizes until it completes. Contact energy is observed only at the crushed stage.
• The rigid wall forces attain peak value of 1200 N during 25-30 ms of simulation.
• The Time for simulation in .out file is 391.22s , energy error is at -3.1% and no mass error and Hourglass error.

D. CASE 4 :-

1. Open Hypermesh > Radioss userprofile.

2. Open Applications > Hypercrash, set KN mm ms kg unit system.

3. Import the crushtube_0000.rad file.

4. Align nodes (F7) is used to remove the notches and delete boundary conditions. Select all the checkboxes like rigid wall, properties, parts, contact interfaces. Add TH for part in Data History and save.

5. Export model to the case4 folder.

6. Import the model in Hypermesh, go to Analysis > Radioss , save as case4 and run.

7. Plot the energy graph and rigid wall forces.

• The Energy graph plotted between internal energy, Total Energy and contact energy is plotted. Internal Energy increases abruptly upto 45000 J after 25 ms of simulation and then stabilizes until it completes. Contact energy is observed only at the crushed stage.
• The rigid wall forces attain peak value of 1000 N during 25-30 ms of simulation.
• The Time for simulation in .out file is 354.04s , energy error is at -2.1% and no mass error and Hourglass error.

E. CASE 5 :-

1. Open Hypermesh > Radioss userprofile.

2. Open Applications > Hypercrash, set KN mm ms kg unit system.

3. Import the crushtube_0000.rad file.

4. Create a notch in the middle using Mesh editing > move , under Defined Displacement select the nodes , vector and distance.

5. Select all the checkboxes like rigid wall, properties, parts, contact interfaces. Add TH for part in Data History and save.

6. Export model to the Case5 folder.

7. Import the model in Hypermesh, go to Analysis > Radioss , save as case5 and run.

8. Von mises representation

9. Plot the rigid wall forces and energies graph.

• The Energy graph plotted between internal energy, Total Energy and contact energy is plotted. Internal Energy increases abruptly upto 45000 J after 25 ms of simulation and then stabilizes until it completes. Contact energy is observed only at the crushed stage.
• The rigid wall forces attain peak value of 1200 N during 25-30 ms of simulation.
• The Time for simulation in .out file is 313.28s , energy error is at -2.3% and no mass error and Hourglass error.

F. CASE 6 :-

1. Open Hypermesh > Radioss userprofile.

2. Open Applications > Hypercrash, set KN mm ms kg unit system.

3. Import the crushtube_0000.rad file.

4. Create a new notch in oppsite sides using Mesh editing > move , under Defined Displacement select the nodes , vector and distance.

5. Select all the checkboxes like rigid wall, properties, parts, contact interfaces. Add TH for part in Data History and save.

6. Export model to the Case6 folder.

7. Import the model in Hypermesh, go to Analysis > Radioss , save as case6 and run.

8. Von Mises Representation.

9. Plot Energy graph and Rigid wall forces.

• The Energy graph plotted between internal energy, Total Energy and contact energy is plotted. Internal Energy increases abruptly upto 45000 J after 25 ms of simulation and then stabilizes until it completes. Contact energy is observed only at the crushed stage.
• The rigid wall forces attain peak value of 1200 N during 25-30 ms of simulation.
• The Time for simulation in .out file is 375.45s , energy error is at -2.6% and no mass error and Hourglass error.

COMPARISON : (Notch Design)

When there is no notch Case4, the crushing happens uniform through out the entire tube.

When notches were created in middle Case5, the crushing happens in the notch once the tube hits rigid wall and proceeds the uniform crushing pattern to remaining areas.

When notches were present in only 2 opposite sides Case6, the sides are subjected to deformation first when tube hits rigid wall and then remaining areas are affected.

Contact energy is seen Highest in CASE 6 due to 2 opposite notches.

(Energy Comparison)

The Internal Energy changes increase similarly for all cases but the peak value varies in each case. The Case4 with no notch experience least internal energy in simulation.

The Contact Energy has no significant leap in the graph.

(Rigid wall Forces )

The Total resultant forces of each case is compared and case4 with no notch observed a less peak value of 1000N. While remaining all Type 11 cases have 1200N.

LINK FOR BUMPER ASSEMBLY AND CASE1-6 : https://drive.google.com/file/d/1HM6tYFw5qELS9lWoTCpdSeE4yZk0inCX/view?usp=sharing

CONCLUSION :

1. The Bumper Assembly is meshed with 6mm and connections are represented.

2. Six cases are simulated with edge to edge and node to surface types. and reported

3. The Case with no notch have significant reduction in internal energy is observed.

4. Energy graphs and Rigidwall Forces graphs are plotted for all cases and compared.