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

AIM: To observe and study the Radioss interfaces effect of notches using Altair Hypermesh.

Software: Altair Hypermesh,Hyperview, Hypergraph 2D.

Objectives:

1. To create mesh on bumper assembly,mesh size is 6mm.
2. To apply and analyze the different cases for the crash tube model.
3. To study the effect of different notches on the crash tube.
4. To plot the Rigidwall forces, Internal energy and Contact energy graphs.
5. To compare the case setups using the number of cycles, energy error, mass error, simulation time, and maximum Von misses
   stress.
6. To study the simulation animations.
7. To analyze and conclude the case results.

Procedure:

Model-1

• Import the model in Hypermesh.
• Go to FILE > IMPORT > MODEL > BROWSE > OPEN > IMPORT.
• Then the model will be imported to the hypermesh window.

• Go to GEOM > TEMP NODES > CLEAR ALL to delete the temporary nodes.
• Go to GEOM > SURFACE EDIT >TRIM WITH SURFS > SELF INTERSECTING SURFS > TRIM.

• Then the self intersecting surfaces wilol be trimmed and appears in yellow lines.

Still there are surfaces which are to be connected.

Automesh:

• Go to 2D > Automesh > Surfs > All.
• Element size=6
• Mesh Type= Quads

• Click on mesh,
• Change the number of nodes to get perfect mesh.

Thus the mesh is generated on the bumper system.

CASE-1 (Run the crash model as it it):

• Import the .Rad file to the solver deck.

• The graphical area can be seen as below.

• Goto Solver > TH > CREATE > INTER.
• Select the entities as bothe seamweld and self contact.

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.
• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.
• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Click on view Results, which will open Hyperview window.

• In Hyperview go to CONTOUR > RESULT TYPE > VON MISES > AVERAGING METHOD > SIMPLE > APPLY.

Post Processing:

• Open Hypergraph 2D and load T01 file.
• Go to GLOBAL VARIABLES > INTERNAL ENEGRY, KINETIC ENERGY and TOTAL ENERGY > MAG > APPLY.
• This will plot the graph.
• The Kinetic energy having higher value at the start of the simulation eventually starts to reduce with time as it gets
  converted into Internal energy, because the can is being crushed.
• Thus, the total energy remains constant with respect to time, but we can see a slight drop in energy at time equals to 25ms.
• This is because the tube is totally crushed and the energy is lost to the friction between the elements.

Contact Energy:

• Go to GLOBAL VARIABLES > CONTACT ENERGY> MAG > APPLY. This will plot the energy graph.
• The contact energy increases initilly at a slow pace and rapidly between 20 to 26 ms, because after 20 ms the tube
  deformation is completed and the force is crushing the surface of the tube in the formation of the folded layers.
• Here, the corner surfaces come in close contact of each other, resulting in the spring formation to repell the surfaces from intersecting
  each other.

Resultant Forces:

• Go to GLOBAL VARIABLES > RWALL > NORMAL RESULTANT, TANGENT AND TOTAL FORCES > APPLY. This will plot the
  rigid wall forces.
• A pattern is observed in the Resultant normal force, where a small amount of force increases at a regular interval of time.
• This increase in the force is when the corner edges fold the tube and the slave nodes try to penetrate into the master
  surface, the spring stiffness increase the force to oppose the slave node.
• After 20 ms we see a greater rise in the force value.
• as the tube is crushed and more no of nodes come closer. Then the force is reduced and reaches to zero value.

CASE-2 (Change the Inact=6 & Run):

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.
• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Click on view Results, which will open Hyperview window.
• In Hyperview go to CONTOUR > RESULT TYPE > VON MISES > AVERAGING METHOD > SIMPLE > APPLY.

• The simulation is same as the case 1 simulation. There is no Geometric change in the model and also in the maximum stress
  and the strain values.
• The only change in this case is that Inacti6 is set, which reduces the gap and uses the scaling.
• Inacti6 removes the initial penetration and moves nodes 30% of the initial gap to avoid contact stability issues.
• As this is performed before the simulation, we observe no difference in the simulation as in case 1.

Post-Processing:

• Open Hypergraph 2D and load T01 file.
• Go to GLOBAL VARIABLES > INTERNAL ENEGRY, KINETIC ENERGY and TOTAL ENERGY > MAG > APPLY. This will plot the
  energy graph.
• The energy graph is same as the case 1.

Contact Energy:

• Go to GLOBAL VARIABLES > CONTACT ENERGY> MAG > APPLY.
• This will plot the energy graph.
• The contact energy increases when the friction contact is defined. At 20 ms the contact energy increases due to the friction formulation defined.

Resultant Forces:

• Go to GLOBAL VARIABLES > RWALL > NORMAL RESULTANT, TANGENT AND TOTAL FORCES > APPLY.
• This will plot the rigid wall forces.
• The force graph is similar to the earlier case. The resultant normal force and total resultant force is similar as the variation in
  resultant tangent force is negligible.

CASE-3 (Create the Type-11 Contact & Run):

• Create the Type-11 contact.
• set the parameters as follows.

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.

• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Click on view Results, which will open Hyperview window.
• In Hyperview go to CONTOUR > RESULT TYPE > VON MISES > AVERAGING METHOD > SIMPLE > APPLY.

Post-Processing:

• Open Hypergraph 2D and load T01 file.
• Go to GLOBAL VARIABLES > INTERNAL ENEGRY, KINETIC ENERGY and TOTAL ENERGY > MAG > APPLY.
• This will plot the energy graph.

Contact Energy:

• Go to GLOBAL VARIABLES > CONTACT ENERGY> MAG > APPLY.
• This will plot the energy graph.

Resultant Force:

• Go to GLOBAL VARIABLES > RWALL > NORMAL RESULTANT, TANGENT AND TOTAL FORCES > APPLY.
• This will plot the rigid wall forces.

CASE-4 (Remove the notches & Boundary condition & run):

• Go to FILE > IMPORT > SOLVER DECK > CRUSH TUBE_0000.RAD > IMPORT.
• For this case we have to create a notch at the middle section.
• Hence, first use align option for removing all the notches.

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.

• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Click on view Results, which will open Hyperview window.
• In Hyperview go to CONTOUR > RESULT TYPE > VON MISES > AVERAGING METHOD > SIMPLE > APPLY.

Post Processing:

• Open Hypergraph 2D and load T01 file.
• Go to GLOBAL VARIABLES > INTERNAL ENEGRY, KINETIC ENERGY and TOTAL ENERGY > MAG > APPLY.
• This will plot the energy graph.
• Due to notch removal the drop in the kinetic energy at the end in not seen. Hence, the total energy remains almost
  constant.

CONTACT ENERGY:

• Go to GLOBAL VARIABLES > CONTACT ENERGY> MAG > APPLY. This will plot the energy graph.
• The contact energy is lower than 1600 kgmm2/ms2, where previously the contact energy increased above 2000kgmm2/ms2.
• This reduction is due to less friction between the elements as the notch is removed.

Resultant Forces:

• Go to GLOBAL VARIABLES > RWALL > NORMAL RESULTANT, TANGENT AND TOTAL FORCES > APPLY.
• This will plot the rigid wall forces.
• The resultant normal and the total resultant force is observed to be less than the previous cases. The max force value is 1200 KN where the previous cases recorded upto 1350 KN.
• This drop is due to the removal of the Boundary condition.

CASE-5 (Create a new notch in the middle of the section):

• Go to FILE > IMPORT > SOLVER DECK > CRUSH TUBE_0000.RAD > IMPORT.
• In this we have to create a notch at the middle section.
• Hence, first use align option for removing all the notches and then go to TOOL > TRANSLATE option to create a notch at the middle of the section.

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.

• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Click on view Results, which will open Hyperview window.
• In Hyperview go to CONTOUR > RESULT TYPE > VON MISES > AVERAGING METHOD > SIMPLE > APPLY.

Post Processing:

• Open Hypergraph 2D and load T01 file.
• Go to GLOBAL VARIABLES > INTERNAL ENEGRY, KINETIC ENERGY and TOTAL ENERGY > MAG > APPLY.
• This will plot the energy graph.
• In this graph we can observe a slight reduction in theh kinetic energy and a slight increase in the internal energy at 11ms, where the deformation in the upper section starts.
• This is mainly due to the notch created at the middle section of the tube.

Contact Energy:

• Go to GLOBAL VARIABLES > CONTACT ENERGY> MAG > APPLY. This will plot the energy graph.
• Here we can see that the contact energy slightly increases at the point of shift of deformation. Also the contact energy at the end is above 1500 kgmm2/ms2.

Resultant Forces:

• Go to GLOBAL VARIABLES > RWALL > NORMAL RESULTANT, TANGENT AND TOTAL FORCES > APPLY. This will plot the
  rigid wall forces.
• In the previous cases we observed a slight increase in the forces where the deformation shifted from the notch sections.
• Similarly, a single(as we have only one notch) slight rise and fall in the forces is seen at 11ms where the deformation is shifte
  to the upper section of the tube.

CASE-6 (Create notch only at the opposite nodes):

• Go to FILE > IMPORT > SOLVER DECK > CRUSH TUBE_0000.RAD > IMPORT.
• For this case we have to create a notch with nodes only from opposite two faces.
• Use the align option for removing all the notches.
• Go to TOOL > TRANSLATE option to create a notch on
  the opposite two faces.

• Next Go to ANALYSIS > RADIOSS > INPUT FILE > INCLUDE CONNECTOR > OPTIONS = -NT 4 > RADIOSS.
• This will run the Radioss simulation.

• Open .Out engine file from saved folder and check final value of Energy error, Mass error, Simulation time and Total no of cycles.

• Click on view Results, which will open Hyperview window.
• In Hyperview go to CONTOUR > RESULT TYPE > VON MISES > AVERAGING METHOD > SIMPLE > APPLY.

• Open Hypergraph 2D and load T01 file.
• Go to GLOBAL VARIABLES > INTERNAL ENEGRY, KINETIC ENERGY and TOTAL ENERGY > MAG > APPLY.
• Energy graph will be plotted as below.

Contact Energy:

• As compared to the previous cases the graph does not show slight deformation at 11ms.
• Go to GLOBAL VARIABLES > CONTACT ENERGY> MAG > APPLY. This will plot the energy graph.
• The contact energy recorded is lower than the previous cases. The contact energy at the end is about 1500 kgmm2/ms2.
• The increase in the contact energy at the beginning is very less.
• Go to GLOBAL VARIABLES > RWALL > NORMAL RESULTANT, TANGENT AND TOTAL FORCES > APPLY.
• This will plot the Rigid wall forces.

Total Resultant Force:

The total resultant force shows ups and downs also at the peak region. There is more deviation in the Resultant Tangent
Force.

RESULTS:

Case.No:	Total No. of Cycles	Energy Error	Mass Error	Simulation Run Time	Max.Von Misses Stresses
1	83529	-3.8%	0%	112.92s	0.6949
2	83529	-3.8%	0%	116.11s	0.6953
3	83336	-4.0%	0%	78.66s	0.6441
4	78386	-3.0%	0%	111.50s	0.6533
5	79918	-2.9%	0%	105.96s	0.6280
6	73455	-2.9%	0%	67.00s	0.6560

CASE-STUDY:

• Here type 7 interface is used for the first two cases and then the type 11 contact is created. Hence. both the interface work together making the simulation stable. The deformation of the tube is observed to be in layers, where the slave nodes try to enter the master gap, the penalty method creates a spring and resistive forces are applied. The energy error is caused when the stiffness value increases to a greater value, minimizing the time step and hence the elements are deleted. The deletion of the elements releases the energy.
• In the second case, we only observe the change in simulation time, because the Inacti6 is set which performs initial
  penetration checks before the simulation.
• In the third case the type 7 and type 11 interface work together increasing the simulation time. The energy error is also
  increased.
• In the fourth case. we observe less no of cycles and lower energy error as the boundary conditions and the notches are
  removed.
• In the fifth case, we observe the increase in the energy error due to the notch created at the middle section here the four components are closer to each other when deformed.
• In sixth case, we observe the no of cycles to be the greatest among all the cases. Also there is reduction in the energy error as opposite face notch is created.

OBSERVATION OUTCOMES:

• To apply the different interfaces for the components.
• To study the results of the interface types..
• To understand the parameter checks before simulation and during simulation.
• The significance of Inacti 6.
• To plot the energy and the rigid wall forces.

CONCLUSION:

• Hence, by performing this project we conclude that the we have studied the type 7 and type 11 interface and also their working together.
• We also studied the effect of notches based upon their location and no of notches.
• The parameters checked before the simulation and during the simulation are also studied.