Assignment 5-RADIOSS Interfaces & Study of Effect of Notches Challenge
AIM: To observe and study the Radioss interface effects of notches using Hyper-mesh.
OBJECTIVES:
- To create mesh on bumper assembly
- Mesh size is 6mm.
- To apply and analyze the different cases for the crash tube model.
- To study the effect of different notches on the crash tube.
- To plot the Rigid wall forces, Internal energy and Contact energy graphs.
- To compare the case setups using the number of cycles, energy error, mass error, simulation time, and maximum Von misses
stress. - To study the simulation animations.
- To analyze and conclude the case results.
PROCEDURE:
MODEL _1
- Now after importing the model, we need change it into topo
- 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 line will appear in yellow line.
- Still there are some spaces which are to be connected before meshing.
Auto mesh:
- Click on the mesh.
- Change the no.of nodes to get the perfect mesh.
Check for free edges:
- we have to check for free edges (red lines) in the component.
- Edges Tool will help us find this error:
- Tool >> Edges [Shift + F3] >> Elem's >> Select by box selection >> Find edges
- If free edges are present, connectivity won't be established between the surfaces.
- As a result, when force is applied on any surface it won't be distributed to the neighboring surface due to a connectivity issue.
- we can create 1d connections between crash box and bumper system, go to 1D -> connectors -> spot
- select the nodes we wanted to create connections between and select the 2 components.
- Now we can reflect the half part to get the complete bumper system model, go to Tools -> Reflect,
MESHED BUMPER SYSTEM:
CASE_1 (Run the crash model as it is)
- Import the (.Rad) file in the solver deck.
- The graphical area can be seen with the model.
- Goto Solver > TH > CREATE > INTER.
- Select the entities as both seam weld and self-contact.
- We can move to the solver tab.
- This can be enabled through View > Browsers > Hyper mesh > Solver.
- Then, we simply need to right-click in the solver interface and go to create > TH > PART to create TH/PART.
POST PROCESSING:
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.
SELF CONTACT FORCE:
- The self-contact force from the TH inter card helps identify the forces due to the Type 7 contact formulation.
- The max self-contact force is 1337.80 N, which occurs at the end of the simulation, when the crush tube is completely deformed, and maximum number of master and slave segments are in contact with each other.
CASE_2(Change the inact=6 and 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.
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.
SELF CONTACT FORCE
The self-contact force from the TH inter card helps identify the forces due to the Type 7 contact formulation.
The max self-contact force is 1337.8 N, which occurs at the end of the simulation, when the crush tube is completely deformed, and maximum number of master and slave segments are in contact with each other.
CASE 3 (CREATE TYPE 11 CONTACT AND 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.
- 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.
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 NOTCH AND BOUNDARY CONDITION AND 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.
- 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 up to 1300 KN.
- This drop is due to the removal of the Boundary condition.
CASE 5 (create a new notch on the middle and run)
- 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.
- 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 the 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 shifted
to the upper section of the tube.
CASE 6 (Create the notch on 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.
- 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.
OBSERVATIONS AND RESULT:
- Notches are the regions where deformations happen first , due to them being regions of stress concentration.
- But it does help to control and predict the location of deformations.
- This in turn plays a role in how the absorbed energy spreads throughout the tube.
- A notched tube results in higher contact forces but a smoother transmission of load.
- In this assignment, different types of contacts were used to analyze the simulations of the crash tube.
- Under a constant load, the behaviour was observed by varying the geometry through the removal and creation of notches.