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

Aim :- To Create the mesh for bumper assembly, mesh size should be 6mm and simulate the given model with all the different cases given in raddios as per problem statement and compare it using various plots.

Questions:

• 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.

Note:

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

Meshing:

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

Step1: Import given model into hypermesh
To Open the .hm file, Go to the File menu in the Standard menu bar >> Click Open >> Click Model >> Select the model to open >> click

Step2: Clean the the geometry, remove all the free edges.

Step3: To perform a mesh, Select Auto mesh option from the 2D panel >> Click the Surface to mesh >> Give the Element size as 6 >> Click mesh.

Step 4: Giving proper connections :-
Now we have create a connection between the crash box and rear bumper. So go to connectors - seam and provide the necessary values.

We have to connect the crash box and rear bumper, so as to give accurate result when we perform the analysis. There are different types of connections are available, apart from this we have chosen seam weld which is used to connect the two different materials. The below diagram shows the seam connection between the crash box and rear bumper.

Case1 :

Run the crash tube model as it is.

Step1: Import the model Crush_tube_0000.rad in Hypercrash. In this model, only two interface contacts are defined which are Type 2 and Type 7. The contact interface properties are as below.

Then export model and open in Hypermesh for the run. Go to solver browser, create TH/PART. Then in the analysis tab save the model as Crush_tube_0000.rad to folder and press tab Radioss to run the analysis.

Energy error is -3.8% and mass error 0 and no of cycles are 83500

Open in the Hyperview to see the animation.

The check for the energy error acceptance criteria and plot energy graphs in Hypergraph 2D:

• For this simulation, the max von mises stress is created as 69.53N/mm2 and the max contact force is created as 82 N. whereas the time history (TH) for all the components are created in order to study the deformation and energy variation in each component with respect to time.
• The Internal energy for the p_shell_2 components is increasing at the beginning because it is attached to the rigid wall and deform smoothly at the notch area where as the stiffness is less at this parts. the Internal energy for the p_shell_3 components is zero for 10ms and linearly increasing to deform (compression takes place) and the stiffness is high for this parts because of flat surface area.
• The Kinetic energy for the p_shell_2 components is varying at the beginning for 10ms and maintained as constant which means no more deformation occurs. Because of Notch area presents over the components it deforms very quickly. The Kinetic energy for the p_shell_3 components is continuously varying over the time 25ms means deformation takes place (compression) at a velocity of 13.3 m/

Case2:

Change the Inacti=6 and run.

Import the model Crush_tube_0000.rad in Hypercrash. In this model, only two interface contacts are defined which are Type 2 and Type 7. The contact interface properties are as below change Inacti =6. Then export the model as Crush_tube_Case2_0000.rad and open in Hypermesh for the run.

Then in the analysis tab save the model as Crush_tube_Case2_0000.rad to folder and press tab Radioss to run the analysis.
In the same folder, you will find one file with the name Crush_tube_Case2_0001.out which will give the energy and mass error along with simulation time.

Then in the analysis tab save the model as Crush_tube_Case2_0000.rad to folder and press tab Radioss to run the analysis. In the same folder, you will find one file with the name Crush_tube_Case2_0001.out which will give the energy and mass error along with simulation time.

Energy error is -3.8% and mass error 0 and no of cycles are 83500

Open in the Hyperview to see the animation.

The check for the energy error acceptance criteria and plot energy graphs in Hypergraph 2D.

• For this simulation, the max von mises stress is created as 69.53N/mm2 and the max contact force is created as 3 N whereas the time history (TH) for all the components are created in order to study the deformation and energy variation in each component with respect to time.
• The Internal energy for the p_shell_2.0 components is increasing at the beginning because it is attached to the rigid wall and deform smoothly from the notch area where as the stiffness is less at this part. The Internal energy for the 0 components is zero for 10ms and linearly increasing to deform (compression takes place) at a velocity 13.3 m/s and the stiffness is high for this part because of flat surface area.
• The Kinetic energy for the p_shell_2.0 components is varying at the beginning for 10ms and maintained constant which means no more deformation occurs. Because of Notch area presents over the components it deforms very quickly. The Kinetic energy for the p_shell_3.0 components is continuously varying over the time 25ms means deformation takes place (compression) at a velocity of 13.3 m/s

Case3:

Create the type 11 contact and run.

In this case, the model is imported and run the simulation with recommended properties whereas we have to change Card image as Type 11 contact as per problem statement.

Type 11 takes into the account of the connections made by the edges of the slave segment to the edges to master segment and hence improves the accuracy of the reactive forces calculations

Then export the model as Crush_tube_Case3_0000.rad and open in Hypermesh for the run. Go to solver browser, create TH/PART. Then in the analysis tab save the model as Crush_tube_Case3_0000.rad to folder and press tab Radioss to run the analysis. In the same folder, you will find one file with the name Crush_tube_Case3_0001.out which will give the energy and mass error along with simulation time.

Energy error is -0.4% and number of cycles are 102100.

open the .h3d in the hyperview to see the animation.

• For this simulation, the max contact force is created as 112.5 N whereas the time history (TH) for all the components are created in order to study the deformation and energy variation in each component with respect to time.
• The Internal energy for the 2mm shell components is increasing at the beginning because it is attached to the rigid wall and deform smoothly from the notch area where as the stiffness is less at this part. The Internal energy for the 3mm shell components is zero for 10ms and linearly increasing to deform (compression takes place) at a velocity 13.3 m/s and the stiffness is high for this part because of flat surface area. The end of this components defines the rigidity with a translational (z-direction) degree of freedom.
• The Kinetic energy for the 2mm shell components is varying at the beginning for 10ms and maintained as constant which means no more deformation occurs. Because of Notch area presents over the components it deforms very quickly. The Kinetic energy for the 3mm shell components is continuously varying over the time 25ms means deformation takes place (compression) at a velocity of 13.3 m/s.

Case4:

Remove both notches and remove boundary condition on rigid body node then run.

Import the model Crush_tube_Case1_0000.rad in Hypercrash. In this model, only two interface contacts are defined which are Type 2 and Type 7. The contact interface properties use as per Case 3
Remove the boundary (Uncheck the translation and rotation in X, Y, and Z direction).

Now open the exported model in hypermesh and use align in node edit to remove the notch do it the all the nodes and remove the notches, as shown in the image.

After removing the both notches then crash tube looks like this.

To simulate the model, go to the Analysis Panel, Select the Radioss Option > Select the area to save the file (Note: Save the File in separate folder naming Case 4 as it will be easy to check the models) > Check include collectors box > In the options tab, type “-nt 4” > Click Radioss. The Simulation is run.

Then run the simulation and open the out put file.

Energy error is -3.1% and number of cycles are 80600.

• For this simulation, the max contact force is created as 61.09 N where as the time history (TH) for all the components are created inorder to study the
  deformation and energy variation in each component wrt to time.
• The Internal energy for the p_shell_2.0 components is increasing at the beginning because it is attached to the rigid wall and deform smoothly there is
  no notch area where as the stiffness is constant over all the model. The Internal energy for the p_shell_3.0 components is zero for 10ms and linearly
  increasing to deform (compression takes place) at a velocity 13.3 m/s. The end of this components defines the rigidity with a translational (z-direction)
  degree of freedom. The Total energy for all the 4 components are varying individually with absence of boundary conditions.
• The Kinetic energy for the p_shell_2.0 components is varying at the beginning for 10ms and maintained as constant which means no more deformation
  occurs. Because of Notch area presents over the components it deforms very quickly. The Kinetic energy for the p_shell_3.0 components is continuously
  varying over the time 25ms means deformation takes place (compression) at a velocity of 13.3 m/s.

Case5:

Create a new notch in the middle ,select the whole section and run.

In this case, the model is imported and run the simulation with recommended properties where there is Notch presented on the middle surface and also the boundary conditions are removed. The Notch is created with the magnitude or depth of 3mm. The Type 11 contact interface is used with recommended property as shown in the Figure.

To simulate the model, go to the Analysis Panel, Select the Radioss Option > Select the area to save the file (Note: Save the File in separate folder naming Case 5 as it will be easy to check the models) > Check include collectors box > In the options tab, type “-nt 4” > Click Radioss.

Open the .out file to see the results.

Energy error is -2.9% and number of cycles are 81300.

The check for the energy error acceptance criteria and plot energy graphs in Hypergraph 2D

• Internal energy has exceeded the value 40000J
• Kinetic energy came down from max value near to 45000J
• Total Energy is almost constant around 45000J

There is a sudden rise in the force value after 20ms up to 1400KN.

• For this simulation, the max contact force is created as 61.94 N where as the time history (TH) for all the components are created in order to study the
  deformation and energy variation in each component with respect to time.
• The Internal energy for the p_shell_2.0 components is increasing at the beginning because it is attached to the rigid wall and deform smoothly there is
  no notch area where as the stiffness is constant over all the model. The Internal energy for the p_shell_3.0 components is zero for 10ms and linearly
  increasing to deform (compression takes place) at a velocity 13.3 m/s. The end of this components defines the rigidity with a translational (z-direction)
  degree of freedom. The Total energy for all the 4 components are varying individually with absence of boundary conditions.
• The Kinetic energy for the p_shell_2.0 components is varying at the beginning for 10ms and maintained as constant which means no more deformation
  occurs. Because of Notch area presents over the components it deforms very quickly. The Kinetic energy for the p_shell_3.0 components is continuously
  varying over the time 25ms means deformation takes place (compression) at a velocity of 13.3 m/s.

The change in the internal energy is due to the notch. With the removal of the notch, the internal energy decreases and hence reduces the energy error as well.

The notch areas have high stresses and deform first. In the plane surface where the notches are removed the stress levels are low. Hence, we can state that by removing the notch helps to reduce the stress acting in the body.

3mm shell is requires higher internal energy; it means ability to absorb force is higher in shell with 3mm thickness compared to shell with 2mm thickness. More thickness of shell has more internal energy the component.

Conclusion :-
The Bumper model have been meshed and welded (seam) with the element size of 6mm and ready for further solving and post-processing. All the 6 cases of crash tube have been simulated and results are compared using various energies plot.