Meshing of a Bumper component and Performing a simulation of a Crash tube with different contact interface options.

OBJECTIVES

1. To understand the different contact interfaces.
2. To understand the different variation of interfaces.
3. To assign recommended contact interface parameters for crash analysis.
4. To understand the advantages and disadvantages of contact interface parameters for crash analysis.
5. To plot the different contours formed with the use of various contact interfaces and parameter change.

CREATE THE MESH FOR BUMPER ASSEMBLY, MESH SIZE SHOULD BE 6MM

• Open the file Bumper_System.
• It will appear in wireframe mode.
• Click on the shaded mesh to view the surfaces in shaded form.

• Click on 2D mesh panel and hit auto mesh with a size of 6mm to mesh the surfaces.

CASE 1 Run the crash tube model as it is

• Import the engine input file (Crush_tube_0000.rad) from import tab in a solver deck.
• It will appear in wireframe mode.

• Click on shaded mesh to view the mesh in shaded form

• Now click on the analysis tab and select as Radioss as a solver.
• Give the input file destination as the solvers create a lot of instantaneous files, so better to save the files in a specific folder.
• The export option should be all – it will take all the components hidden too.
• Number of the run as 1 and Run option as analysis
• Options should be (-nt 4 means four CPU solves problems at a time)
• Click on the shaded mesh to view the mesh in shaded form.
• After completion of Radioss analysis, you will get the result card.

• Now change the mode from hyper mesh to hyper view
• Load the model of files created folder the file should be in the form of .h3d
• .h3d file is an animation file that is a combined file of animation files (A01, A02, A03….)

                             

• Click on the contours option to get the different required result values of stress, Rwall forces, Contact forces, Internal Energy, hourglass energy etc.

• If you want to plot different graphs. Change the mode to hypergraph 2D.
• Hyper graph can be accessed with the file name with format (runname_T01). This file format should be in runname_T01

 

 

 

 

 CASE 2 Change In_acti =6 and Run the model.

• Import the engine input file (Crush_tube_0000.rad) from import tab in a solver deck.

• It will appear in wireframe mode.
• Click on shaded mesh to view the mesh in shaded form

• Action to take if initial penetration. Removal of initial penetration where possible. Elsewhere, reduce to less than 30% of defined gap value and adjust the gap by using in In
• Here are the chances of initial penetration of elements.

 

• Now click on analysis tab and select as Radioss as a solver.
• Give the input file destination as the solvers create lot of instantaneous files, so better to save the files in a specific folder.
• The export option should be all – it will take all the components hidden too.
• Number of run as 1 and Run option as analysis
• Options should be (-nt 4 means four CPU solves problems at a time)
• After completion of Radioss analysis, you will get the result card.

 

• Now change the mode from hyper mesh to hyper view
• Load the model of files created folder the file should be in the form of .h3d
• .h3d file is an animation file which is a combined file of animation files (A01, A02, A03….)

                     

• Click on the contours option to get the different required result values of stress, Rwall forces, Contact forces, Internal Energy, hourglass energy etc.

• If you want to plot different graphs. Change the mode to hypergraph 2D.
• The hyper graph can be accessed with the file name with format (runname_T01). This file format should be in runname_T01

CASE 3 Create the Type 11 contact and run.

• Import the engine input file (Crush_tube_0000.rad) from import tab in a solver deck.

• It will appear in wireframe mode.
• Click on the shaded mesh to view the mesh in shaded form

• Type 11 contact is for Edge to Edge contact
• Interface Type 11: Edge to Edge Contact

• In the case of edges crossing, Type 11 interface can be added to capture the physics correctly
• Type 11 is defined by identifying master and slave lines (edges)
• Type 11 works similar to Type 7 in terms of:
• Penalty formulation
  1. Gap definition
  2. Search method

• Now click on the analysis tab and select as Radioss as a solver.

• Give the input file destination as the solvers create a lot of instantaneous files, so better to save the files in a specific folder.
• The export option should be all – it will take all the components hidden too.
• Number of the run as 1 and Run option as analysis
• Options should be (-nt 4 means four CPU solves problems at a time)
• After completion of Radioss analysis, you will get the result card.

• Now change the mode from hyper mesh to hyper view
• Load the model of files created folder the file should be in the form of .h3d
• .h3d file is an animation file that is a combined file of animation files (A01, A02, A03….)

                                

• Click on the contours option to get the different required result values of stress, Rwall forces, Contact forces, Internal Energy, hourglass energy etc.

• If you want to plot different graphs. Change the mode to hypergraph 2D.
• Hyper graph can be accessed with the file name with format (runname_T01). This file format should be in runname_T01

 

 

CASE 4 Remove both notches and remove boundary conditions on rigid body node and run.

• Import the engine input file (Crush_tube_0000.rad) from the import tab in a solver deck.
• It will appear in wireframe mode.

• Click on the shaded mesh to view the mesh in shaded form.
• For the removal of the notch, we can use the align node command to align the elements properly.

 

• After removal of both the notch we get the clear pipe.

• Removal of Boundary conditions we are making free the pipe to crush.

 

 

 

• Now click on the analysis tab and select as Radioss as a solver.

• Give the input file destination as the solvers create lot of instantaneous files, so better to save the files in a specific folder.
• Export option should be all – it will take the all the components hidden too.
• Number of run as 1 and Run option as analysis
• Options should be (-nt 4 means four CPU solves problems at a time)
• After completion of Radioss analysis you will get result card.

• Now change the mode from hyper mesh to hyper view
• Load the model of files created folder the file should be in the form of .h3d
• .h3d file is an animation file that is combined file of animation files (A01, A02, A03….)
• Click on the contours option to get the different required result values of stress, Rwall forces, Contact forces, Internal Energy, hourglass energy etc.

 

• If you want to plot different graphs. Change the mode to hypergraph 2D.
• The hyper graph can be accessed with the file name with format (runname_T01). This file format should be in runname_T01

 

 

CASE 5 create a new notch in middle Select the whole section and run.

• Import the engine input file (Crush_tube_0000.rad) from import tab in a solver deck.

• It will appear in wireframe mode.
• Click on the shaded mesh to view the mesh in shaded form.
• For removal of the notch, we can use align node command to align the elements properly.

• After removal of both the notch we get the clear pipe.

• Removal of Boundary conditions we are making free the pipe to crush.

 

 

• Now click on analysis tab and select as Radioss as a solver.

• Give the input file destination as the solvers create a lot of instantaneous files, so better to save the files in a specific folder.
• The export option should be all – it will take all the components hidden too.
• Number of the run as 1 and Run option as analysis
• Options should be (-nt 4 means four CPU solves problems at a time)
• After completion of Radioss analysis you will get the result card.

• Now change the mode from hyper mesh to hyper view
• Load the model of files created folder the file should be in the form of .h3d
• .h3d file is an animation file that is a combined file of animation files (A01, A02, A03….)
• Click on the contours option to get the different required result values of stress, Rwall forces, Contact forces, Internal Energy, hourglass energy etc.

• If you want to plot different graphs. Change the mode to hypergraph 2D.
• Hyper graph can be accessed with the file name with format (runname_T01). This file format should be in runname_T01

 

 

CASE 6 create a new notch in middle Select the whole section and run.

• Import the engine input file (Crush_tube_0000.rad) from the import tab in a solver deck.

• It will appear in wireframe mode.
• Click on the shaded mesh to view the mesh in shaded form.
• For the removal of the notch, we can use the align node command to align the elements properly.

• After the removal of both the notch, we get the clear pipe.

• Removal of Boundary conditions we are making free the pipe to crush.
• Creation of notch using offset elements using 2d offset.
• Now click on analysis tab and select as Radioss as a solver.

• Give the input file destination as the solvers create a lot of instantaneous files, so better to save the files in a specific folder.
• The export option should be all – it will take all the components hidden too.
• Number of the run as 1 and Run option as analysis
• Options should be (-nt 4 means four CPU solves problems at a time)
• After completion of Radioss analysis, you will get the result card.

• Now change the mode from hyper mesh to hyper view
• Load the model of files created folder the file should be in the form of .h3d
• .h3d file is an animation file that is a combined file of animation files (A01, A02, A03….)
• Click on the contours option to get the different required result values of stress, Rwall forces, Contact forces, Internal Energy, hourglass energy etc.

• If you want to plot different graphs. Change the mode to hypergraph 2D.
• The hyper graph can be accessed with the file name with format (runname_T01). This file format should be in runname_T01

COMPARISION

SR.NO	CASE NAME	TOTAL NO.OF CYCLE	ENERGY ERROR	MASS ERROR	SIMULATION TIME
1	CASE 1 Run the crash tube model as it is	83724	-3.8	0	269.29 s
2	CASE 2 Change Inacti =6 and Run the model.	83724	-3.8	0	273.42
3	CASE 3 Create the Type 11 contact and run.	103616	-7.6	0	566.55
4	CASE 4 Remove both notches and remove boundary conditions on rigid body node and run.	77673	-3.0	0	255.20
5	CASE 5 create a new notch in middle Select the whole section and run.	89051	-3.7	0	351.86
6	CASE 6 create a new notch in middle Select the whole section and run.	92991	-4.2	0	366.40

 

The Energy Error computed by RADIOSS is a percentage.

• If the error is negative, it means that some energy has been dissipated.
• Negative Energy Error since it is not counted in the energy balance. The normal amount of Hourglass energy is about 10% to15%.
• If the error is positive, there is an energy creation. In case of using QEPH shell formulation or fully integrated elements, the Energy
• The error can be slightly positive since there is no Hourglass energy and the computation is much more accurate. An error of 1%or 2% will be acceptable.

The Mass error is 0% which is acceptable as no change has happened to mass.

The Simulation time for CASE 3 Create the Type 11 contact is much more compared to others.

• Action to take if initial penetration. Removal of initial penetration where possible. Elsewhere, reduce to less than 30% of defined gap value and adjust the gap by using in Inacti.
• When we are using no failure criteria simulation time required is quite less as compared to others.

          Internal and Kinetic Energy CASE 4                        Internal and Kinetic Energy CASE 3

                              R WALL CASE 4                                 R WALL CASE 3

      CONTACT FORCES CASE 4                                                  CONTACT FORCES CASE 3

 

     CONTACT FORCES CASE 6                                            CONTACT FORCES CASE 5

     R WALL CASE 6                                                                 R WALL CASE 5

 

  Internal and Kinetic Energy CASE 6                                       Internal and Kinetic Energy CASE 5

 

CONCLUSION:

1. There are two different types of radioss files namely engine file (runname_0001.rad) and starter file (runname_0000.rad).
2. Learn about how to change the different contact interfaces of the Radioss solver.
3. Studied the different variations of interfaces.
4. Learn to assign recommended contact interface parameters for crash analysis.
5. A General Remark about Master & Slave: The coarser the mesh, the stiffer the structure will be provided the material and structural properties are the same. Hence, the Master has typically meshed coarser so that the Slave does not penetrate into master. That is why we choose less deformable or high stiffer structure as master and less stiff as a slave.
6. QEPH cell formation for fully integrated elements the energy error can be slightly positive since there is no hourglass energy and the computation is much more accurate.
7. An error of one or two percent will be acceptable otherwise any positive energy error means energy has been created which indicates a model issue. Here in case 3, the energy error is quite high.
8. The Mass error is 0% which is acceptable as no change has happened to mass.
9. To plot the different contours formed with the use of various material laws and parameter change.