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.

SOFTWARE USED :

Altair hyper-works student version 2021

PROBLEM STATEMENT :

• 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:

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

SOLUTION :

Meshing of bumper assembly :

• Import given model into hypermesh
• The model is displayed in the Graphics Area.
• To perform a mesh, Select Auto mesh option from the 2D panel then Give the Element size as 6 then Click mesh.
• The Mesh is completed and the model is made sure that there are no tria elements in the model.

MESHED MODEL

Giving proper connections :

• Now 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.

MESHED MODEL WITH CONNECTION

SOLVING DIFFERENT CASES ON CRASH TUBE :

CASE 1 :

• Import the Model using import solver deck option

GIVEN MODEL

• The Simulation needs to be performed without changes in model in this case.
• 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.

SIMULATION GIF

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

0001.OUT FILE

• From output file energy error is -3.5% which is less than -15% to 5%
• Mass error is 0% which is less than 1%
• we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.

VARIOUS ENERGY GRAPHS

• As seen in the graph, the kinetic energy is maximum at the beginning which starts decreasing once the crush tube impacts the
  rigid wall.
• This energy is converted into strain energy as the crush tube deforms as observed by the increase in internal energy of the system.
• As total energy reduces, contact energy increases.
• Contact energy = contact force*distance moved to avoid penetration.
• The contact force is basically the energy spent by enabling a contact force to avoid penetration.This should be minimum.
• As seen above,the contact energy is very less for most of the time and there is slight increase in the contact
  energy at the end of simulation.

RIGID WALL FORCE

• For rigid wall, there is sudden rise in the peak value of rigid wall force. By this time, the crush tube is completly crushed
  and therefore the deformed model having no further scope for deformation.
• So it gets pushed against the wall with some velocity to which the rigid wall reacts.

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

PROPERTY

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

SIMULATION GIF

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

0001.OUT FILE

• From output file energy error is -3.8% which is less than -15% to 5%
• Mass error is 0% which is less than 1%
• we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.
• Plot the graphs of energies same as above case.

VARIOUS ENERGY GRAPHS

• As seen in the graph, the kinetic energy is maximum at the beginning which starts decreasing once the crush tube impacts the
  rigid wall.
• This energy is converted into strain energy as the crush tube deforms as observed by the increase in internal energy of the system.
• As total energy reduces, contact energy increases.
• Contact energy = contact force*distance moved to avoid penetration.
• The contact force is basically the energy spent by enabling a contact force to avoid penetration.This should be minimum.
• As seen above,the contact energy is very less for most of the time and there is slight increase in the contact
  energy at the end of simulation.

RIGID WALL FORCE

• For rigid wall, there is sudden rise in the peak value of rigid wall force. By this time, the crush tube is completly crushed
  and therefore the deformed model having no further scope for deformation.
• So it gets pushed against the wall with some velocity to which the rigid wall reacts.

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.
• 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.

PROPERTY

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

SIMULATION GIF

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

0001.OUT FILE

• From output file energy error is -3.9% which is less than -15% to 5%
• Mass error is 0% which is less than 1%
• we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.
• Plot the graphs of energies same as above case.

VARIOUS ENERGY GRAPHS

• As seen in the graph, the kinetic energy is maximum at the beginning which starts decreasing once the crush tube impacts the
  rigid wall.
• This energy is converted into strain energy as the crush tube deforms as observed by the increase in internal energy of the system.
• As total energy reduces, contact energy increases.
• Contact energy = contact force*distance moved to avoid penetration.
• The contact force is basically the energy spent by enabling a contact force to avoid penetration.This should be minimum.
• As seen above,the contact energy is very less for most of the time and there is slight increase in the contact
  energy at the end of simulation.

RIGID WALL FORCE

• For rigid wall, there is sudden rise in the peak value of rigid wall force. By this time, the crush tube is completly crushed
  and therefore the deformed model having no further scope for deformation.
• So it gets pushed against the wall with some velocity to which the rigid wall reacts.

CASE 4 :

• In this case, the notch needs to be deleted and make it into a plane mesh.
• To remove the Notch, go to align node option then align node in straight.
• Now the Notch elements are came straight.

MODEL WITHOUT NOTCHE

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

BOUNDARY CONDITION

• 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.

SIMULATION GIF

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

0001.OUT FILE

• From output file energy error is -3.0% which is less than -15% to 5%
• Mass error is 0% which is less than 1%
• we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.
• Plot the graphs of energies same as above case.

VARIOUS ENERGY GRAPHS

• As seen in the graph, the kinetic energy is maximum at the beginning which starts decreasing once the crush tube impacts the
  rigid wall.
• This energy is converted into strain energy as the crush tube deforms as observed by the increase in internal energy of the system.
• As total energy reduces, contact energy increases.
• Contact energy = contact force*distance moved to avoid penetration.
• The contact force is basically the energy spent by enabling a contact force to avoid penetration.This should be minimum.
• As seen above,the contact energy is very less for most of the time and there is slight increase in the contact
  energy at the end of simulation.

RIGID WALL FORCE

• For rigid wall, there is sudden rise in the peak value of rigid wall force. By this time, the crush tube is completly crushed
  and therefore the deformed model having no further scope for deformation.
• So it gets pushed against the wall with some velocity to which the rigid wall reacts.

CASE 5 :

• 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 by using Tool → translate option with the magnitude or depth of 4mm.
• The Type 11 contact interface is used with recommended property.

MODEL WITH CENTER NOTCH

• 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.

SIMULATION GIF

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

0001.OUT FILE

• From output file energy error is -3.6% which is less than -15% to 5%
• Mass error is 0% which is less than 1%
• we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.
• Plot the graphs of energies same as above case

VARIOUS ENERGY GRAPHS

• As seen in the graph, the kinetic energy is maximum at the beginning which starts decreasing once the crush tube impacts the
  rigid wall.
• This energy is converted into strain energy as the crush tube deforms as observed by the increase in internal energy of the system.
• As total energy reduces, contact energy increases.
• Contact energy = contact force*distance moved to avoid penetration.
• The contact force is basically the energy spent by enabling a contact force to avoid penetration.This should be minimum.
• As seen above,the contact energy is very less for most of the time and there is slight increase in the contact
  energy at the end of simulation.

RIGID WALL FORCE

• For rigid wall, there is sudden rise in the peak value of rigid wall force. By this time, the crush tube is completly crushed
  and therefore the deformed model having no further scope for deformation.
• So it gets pushed against the wall with some velocity to which the rigid wall reacts.

CASE 6 :

• In this case, a notch should be created at the same place in the opposite direction.
• To create a notch by using Tool → Translate with the magnitude 4mm.
• Now the Notch is created.

NOTCHES IN OPPOSITE PLANES

• 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

SIMULATION GIF

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

0001.OUT FILE

• From output file energy error is -3.5% which is less than -15% to 5%
• Mass error is 0% which is less than 1%
• we can accept the results and plot the graphs by using hypergraphs.
• Open hypergraph 2d for observing the energy plot data from TA01 file.
• Plot the graphs of energies same as above case

VARIOUS ENERGY GRAPHS

• As seen in the graph, the kinetic energy is maximum at the beginning which starts decreasing once the crush tube impacts the
  rigid wall.
• This energy is converted into strain energy as the crush tube deforms as observed by the increase in internal energy of the system.
• As total energy reduces, contact energy increases.
• Contact energy = contact force*distance moved to avoid penetration.
• The contact force is basically the energy spent by enabling a contact force to avoid penetration.This should be minimum.
• As seen above,the contact energy is very less for most of the time and there is slight increase in the contact
  energy at the end of simulation.

RIGID WALL FORCE

• For rigid wall, there is sudden rise in the peak value of rigid wall force. By this time, the crush tube is completly crushed
  and therefore the deformed model having no further scope for deformation.
• So it gets pushed against the wall with some velocity to which the rigid wall reacts.

LEARNING OUTCOME :

Comparison of energy errors, mass errors, Max. Contact force, Max. Rigid wall force and Max. Contact energy,

1. 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.

2. The notch areas have high stresses and deform first. In the plane surface where the notches are removed the stress

levels are low.

3. Hence, we can state that by removing the notch helps to reduce the stress acting in the body.

CONCLUSION :

• The Bumper model have been meshed with the element size of 6mm and welded Now it is ready for solving and
  post-processing.
• All the 6 cases of crash tube have been simulated and results are compared using various energies plot.