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 seven different cases in radios 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.

Solution :-

Model 1 :- Meshing of bumper assembly

1. 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
• The model is displayed in the Graphics Area.

2. Assign quality parameters :-

• To give the Criteria, Click on the Preferences in the Standard Menu bar >> Click Criteria Menu Settings >> Give Target Element Length as 6mm >> Click Ok.
• The Criteria are given.

3. Meshing :-

• 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.

• The Mesh is completed and the model is made sure that there are no tria elements in the model.

4. Giving proper connections :-

        a. Now we have create a connection between the crash box and rear bumper. So go to connectors - seam and provide the necessary values.

         b. 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.

Model 2 :- Solving different cases on crash tube

Case 1. Run the crash tube model as it is.

• After the Model is imported, The Simulation needs to be performed without changes in model in this case.

• In order to create the THPART we have to click on the output Blocks and create the TH PART , in entity id instead of nodes keep components and select all four components and click on ok. Then the TH part is created.

• To simulate the model, Go to the Analysis tab, Select the Radioss option > Select the location to save the file > Check include collectors box > In the options tab, type “-nt 4” > Click Radioss.

• Open hyperview to view animation and contour plots from H3d file. The simulation is shown in GIF below.

• Open output file and check energy error and mass error as shown in image below.

• From output file energy error is -3.8%% and mass error is 0% which is less than -15% to 2% and 1% respectively, so we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.

• 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/s.  
• The contact energy is varying at a very small amount at the beginning and there is a sudden peak formed because there is large amount of energy developed at the end of deformation. The overall elements are became compressed which will developed large force on the rigid wall around 1400 Newton and energy created as 2 kJ.

Case 2. Change the Inacti=6 and run.

• In this case, the model is imported and run the simulation with recommended properties whereas we have to change Inacti = 6 as per problem statement. The Type 7 contact interface is used with recommended property as shown in the Figure 

• After changing the parameters run the simulation with same steps to be carried as per previous case. The simulation is shown in GIF below. Plot the graphs of energies same as above case.

• 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. 
• The contact energy is varying at a very small amount at the beginning and there is a sudden peak formed because there is large amount of energy developed at the end of deformation. The overall elements are becoming overlapped or compressed which will develop large force on the rigid wall around 1500 Newton and energy created as 2.6 kJ.

Case 3 :- 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.

• 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. 
• The contact energy is varying at a very small amount at the beginning and there is a sudden peak formed because there is large amount of energy developed at the end of deformation. The overall elements are becoming overlapped or compressed which will develop large force on the rigid wall around 1300 Newton and energy created as 1.9 kJ.

Case 4 :- Remove both notches  and remove boundary condition on rigid body node then run.

• In this case, the notch needs to be deleted and make it into a plane mesh.
• To delete the Notch, go to the Tools panel and select Delete option > Select the Elements to delete > Click on delete Entity.
• The Notch elements are deleted.
• To create a plane surface, go to the 2D panel, Select Ruled option > Select the first Node list > Select the Second Node List > Click Create. >> The mesh is created Give the element length as 6 > Click Recalculate > Click mesh.
• The mesh is created properly.

• Now to delete the Boundary conditions, go to the Solver Deck, If the Solver deck is not visible, Go to the View tab in the Standard menu bar > Click Browse > Click Hyper Mesh > Click on Solver > The Solver Deck will be opened. > Delete the BCS Entity in the Solver Deck.

• 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 successfully.

• 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. 
• The contact energy is varying at a very small amount at the beginning and there is a sudden peak formed because there is large amount of energy developed at the end of deformation. The overall elements are became overlapped or compressed which will developed large force on the rigid wall around 1200 Newton and energy created is 1.3 kJ.

Case 5 :- 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. The Simulation is run successfully.

• 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 contact energy is varying at a very small amount at the beginning and there is a sudden peak formed because there is large amount of energy developed at the end of deformation. The overall elements are becoming overlapped or compressed which will develop large force on the rigid wall around 1300 Newton and energy created is 1.7 kJ.

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

• In this case, a notch should be created at the same place in the opposite direction.
• Again, to create a notch, the Translate option is used.
• Go to the Tools panel, Select Translate option > Select the Nodes to translate > Select the Orientation of the elements (i.e., in which direction the elements should be moved) > Give the Magnitude as 5 (Distance from node to node).
• The Notch is created.

• 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 6 as it will be easy to check the models) > Check includes collectors box > In the options tab, type “-nt 4” > Click Radioss. The Simulation is run successfully.

• For this simulation, the max contact force is created as 69.45 N whereas the time history (TH) for all the components is 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 there is notch on the middle opposite 2 surface whereas the stiffness is less. 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. The end of this components defines the rigidity with a translational (z-direction) degree of freedom. The Total energy for all the 4 components is varying individually with absence of boundary conditions.
• 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. 
• When objects collide, contact forces transfer energy so as to change the objects' motions. When two objects interact, each one exerts a force on the other, and these forces can transfer energy between them. Fields contain energy that depends on the arrangement of the objects in the field.
• The contact energy is varying at a very small amount at the beginning and there is a sudden peak formed because there is large amount of energy developed at the end of deformation. The overall elements are becoming overlapped or compressed which will developed large force on the rigid wall around 1100 Newton and energy created as 1.5 kJ.

Results :-

• Comparison of energy errors, mass errors, Max. Contact force, Max. Rigid wall force and Max. Contact energy are given in below table.

• 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.

Result :-  

• 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.