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

OBJECTIVE

• 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.

PROCEDURE:-

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

• 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.

• Switch to By Topo geometry color mode. 

• Go to Preferences > Criteria File Settings > Target element size. Enter Target element size = 6. Now press F12 to go to automesh panel. Enter element size =6 and mesh type to 6.
•  Perform the meshing manually surface by surface.

Giving proper connections :-

• Now connect the crash boxes with the bumper using spot weld. Go to 1D > connectors > spot > spot. In the location selector, select the nodes of the crash box. In connect what selector, select the components to be connected, i.e crash box and bumper rear. enter no. of layers = 2 and search tolerance as 2.5. Select type as weld with diameter = 2 and click on create. The connectors will be created as seen below.

 

Solving different cases on crash tube

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

• We have to run the simulation as it is with no changes. Open Hypermesh with user profile as Radioss. To import the 0000.rad file, click on File > Import > Solver deck and import the file.

• After importing the file,  we can check the defined interface in the model.Type7 interface is used. It is a general purpose interface which can simulate all types of impact between a set of nodes and a master
• In order to create the TH_PART 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 53.2 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 or removed.

• 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 46.32N 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, we have to create a new notch in the centre and run the simulation. We can create notch by using translate option available under Tool page. To properly create the notch, use the N1,N2,N3. option to define the plane of translation. Translate the nodes by 4mm and create the notch.

• 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 365.94 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 78.45 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.

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

Case no.	Particulars	Energy Error (%)	Mass Error (%)	Max. Contact force (N)	Max. Rigid wall force (N)	Max. Contact energy (KJ)	Reason
Case1	Running model as it is	-3.8	0	69.53	1400	2	Node to Surface Contact Type 7
Case2	Change Inacti = 6	-4.8	0	69.53	1500	2.6	No Initial Penetrations found
Case3	Type 11 Interface	-3.9	0	53.2	1300	1.9	Type 11 Edge to Edge Contact
Case4	Removing notches and BC’s	-2.5	0	61.09	1200	1.3	No boundary condition; flat surface
Case5	Creating new notch to middle	-3.6	0	61.94	1300	1.3	ability to absorb increased due to middle notch
Case6	Creating notch only on opposite side	-3.2	0	69.45	1100	1.5	due to Opposing notches

• 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.