Assignment 6-Frontal Crash Simulation Challenge

OBJECTIVE: To perform frontal crash simulation with the given car model and also plot the result from the output request.

PROCEDURE:

1. To import the given model to the radioss GUI.

• Import> selecting file type as radioss>0000.rad>import.
• The file is imported.

2. To Check unit system.

• We can check the unit system from the starter file or from the begin card.

3. To Create appropriate interface ,friction 0.2 and recommended parameters.

Ishell =24		QEPH 4 nodes shells are best combination of cost and accuracy.
Ismstr=2		Full geometric nonlinearities (default)with possible small strain formulation activation in RADIOSS Engine.
Ish3n=2		Standard 3 noded shell (C0)with modification for large rotation(default)
N=5		Number of integration points set to 5 for accuracy bending.
Ithick=1		Thickness change is taken into account for accuracy.
Iplas=1		Iterative plasticity for good accuracy.
Fric=0.2		Frictional forces.

• Right click on the model tree> Create>contact, and provide suitable as above and delete the rest of the interface.

3. To check if there is any penetrations and intersection.

• The penentration is checked in hypercrash software
• To open Hypercrash >hypermesh>application on the tool bar> hypercrash.

• Choosing the SI unit > To import the model> drag the file 0000.rad file to the GUI, the model will be imported.
• To check for pentration in Hypercrash .
• Quailty from hypercrash tool menu> Check all solver contact interface.
• There is no penetration found.

4. Correct rigid bodies if any issues.

• Removed all the unwanted rigid bodies form the model.

5. Create rigid wall with friction 0.1.

• In Hypermesh Right click on the model tree > Create > Rwall
• Geometry type- infinte plane> XM, YM,ZM- Selecting the middle of the bumper.
• Selecting the -1 as the normal.
• Slide> 2. sliding with friction.
• Dsearch 1000.
• Fric is 0.1
• The rigid wall is created.

6. To add masses to reach target weight 700kg while getting CG about the required range.

• Tool menu> Mass> Mass balancing , total mass is 188 kg of the half scale model and the COG point is around the centre console.
• Comparing with full scale model the mass should be 700 kg and cog point should be below at the end and in between passanger and co passanger seat.

• In Hypercrash to add mass, Load case> added mass.
• Create new > Type1> mass> right clicking on support> selecting the nodes in graphics. to add the mass.

• Masses are added in such a way that total mass shoud 700 kg and COG as per determined.
• The mass added are 150 kgs are added at the 1st set of row , 150 and 212 are added in reset of the row
• Total 180+150+150+220=700 kg.
• The COG point is now shifted to the desired location.

5. Initial velocity 35 mph.

• To create the initial velocity card
• Right Click on the solver tree> create> Boundary condition> Inivel
• To convert 35MPH to MMPS
• 1MPH= 0.45MPS
• 35MPG =? 35x0.447=15.64
• Velocity component= 15.64.0.0 , in X direction.

6. Time-step :0.5 to 0.1 microseconds.

• Model tree>cards > ENG_Dota_Noda
• Given 0.5 Micro sec
• Converting 0.5 micro sec to 0.0005 milisec .

7. To Run the simulation for 80 ms.

• Model tree>cards > ENG_Run.
• Tstop=80.0

8. Using model checker to ensure good quality.

• Tools> Model checker> Radioss block>Run checker.
• There no error only warning.
• The warning can be ignored.
• The Unused set is removed by deleting from tools > unused.

9. Creating frame and section in respective position for output section

• By using Temp node to locate the position to create the section.
• Creating frame by right clicking on the solver browser >create> frame > mov selecting the node.
• Creating the Section on the rail, right click> create> Sect.

• Selecting the N1 , N2 and N3 respectively as per the frame.
• Right clicking on the grshel id > create and selecting the element.
• Frame and section is created for all the output request.
• Same procedure is followed for all the Output request.

10. To run the analysis.

• Hypermesh>analysis>Radioss>select the path to be saved.
• Include the connectors and -nt 4 to> Radioss.

• Total Time taken to complete the Cycle is 4hrs.

11. To run the animation.

• Hyperview > Open >H3d File .

• The initial kinetic energy of the car is Maximum as soon as the model crashes into the the rigid wall the kinetic energy is reduced.
• As the kinetic energy reduces the internal energy increases.

Output Requests.

• TH cards are created inorder to plot the required output at that paritcular section.

1. Sectional force in the rails at location of indicated node 174247.

• Using Hypergraph to plot the required output
• From the above graph we can see that the force on the left rail is more compared to right rail.
• At 14ms to 15ms the force has reached its peak in both the rails then the force is reduced.

2. Axial force received on the rails from bumper.

• The axial forces is initially 0 then increases as the car hits the rigid wall.
• The maximum axial force is 32kN/mm2 at 11ms.
• The force is transmitted from bumper to the rail and gradually decreases .

3. Shotgun cross sectional forces.

• The force on the left shotgun is more compared to the right shotgun.
• From the graph Maximum force on the left shotgun is 12KN/mm2 at 38ms and in the right it is 8.8KN/mm2 at 22ms.
• From the animation we can also see that left shotgun has undergone more deformation.

4. A pillar cross section.

• The maximum force on the Left A pillar is 5.5KN/mm2 at 70ms.
• The maximum force on the right A pillar is 3.1KN/mm2 at 22ms.
• Here the deformation is higher in the left A pillar.

5.Acceleration curve received on the accelerometer at base of B pillar.

• From the above graph the Accelertaion has increased and decrease as the body hits the rigid wall and deaccelerates.

6. Intrusions on the dash wall 66695,66244.

• Spring is created to check for the intrusion.
• The Maximum elongation is 101mm and 137mm respectively where the intrusion is very small as seen in the animation.

Conclusion:

• The force is reduced as the as it transmits from one component to another.
• Initially the maximum force experienced on the bumper is 32KN/mm2 > maximum force experienced on rails is 23kN/mm2 >maximum force experienced on shotgun is 13kN/mm2>maximum force experienced on Apillar is 5.5kN/mm2.
• So as the component deforms the force is absorbed and reduced as it travel from one component to another.

RESULT:

Performed the frontal crash simulation with the given car model and results are poltted as per the output request.