Assignment 6-Frontal Crash Simulation Challenge

OBJECTIVE

Frontal crash-BIW

• Check unit system and either follow[Mg mm s] or [Kg mm ms].
• Create appropriate interface ,friction 0.2 and recommended parameters.
• Make sure of no penetrations and intersection.
• Correct rigid bodies if any issues.
• Create rigid wall with friction 0.1.
• Compare the model weight with the full scale 300k nodes model and use added masses to reach target weight 700kg while getting CG about the required range.
• Initial velocity 35 mph.
• Use model checker to ensure good quality.
• Time-step :0.5 to 0.1 microseconds.
• Run 80 ms.

Output requests:

• Sectional force in the rails at location of indicated node 174247.
• Axial force received on the rails from bumper.
• Shotgun cross sectional forces.
• A pillar cross section.
• Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).
• Intrusions on the dash wall 66695,66244.

PROCEDURE

• Open the _0000.rad file in notepad.Check the units written in that.
• Import _0000.rad file in hypermesh with radioss solver.
• Go to model-create- contact.Select the card image as TYPE 7.
• Select g.nod id and surf id as all components.Give Istif= 4,Igap=3,Idel=2,Stmin=1,Gapmin=0.5,Inacti=6,Iform=2,Friction=0.2.
• Go to Tools-penetration checks-select the TYPE7 as group.Check for penetration.
• Go to model-right click-create-rigid wall.
• Select the centre node on the bumper.Select the plane normal to the rigid wall.
• Give search distance as 1000 mm and friction as 0.1.
• Go to Tools- mass details-mass,cog,inertia.Note down the cog coordinates.
• Create a temporary node in that location and identify where we have to add additional mass to take cog to the centre of the rail.
• Go to solver-right click-create-ADMAS.sELECT MASS TYPE =0,select nodes which we have to add mass.Check the COG.
• Go to solver-right click-create-boundary conditions-INIVEL.
• Select all components.Convert 35 mph to mm/mS.
• Go to model-cards-ENG_RUN.give Tstop =80 mS.
• Output requests:
• Isolate the required part which we have to create crossection.
• Go to solver-right click-create-frame-mov.
• Select 3 nodes for orgin,x direction and xy plane.
• Go to solver-right click-create-SECTION-SECT.Select the elements and frame id.give alpha=1.69,Iframe=12,Delt=0.1.
• Go to model-output blocks-right click-create.Rename it as crossection.Select the created crossection.
• Go to solver-right click-create-accelerometer.Select the node.
• Create two frames in the floor rail .Go to solver-right click-create-intrusion.Create two intrusion points.
• Take two accelerometers and intrusions to the output blocks.

RESULT

Rail crossections

Bumper crossections

Shot gun crossections

 Pillar crossections

Acceleration:

Intrusion:

LEARNING OUTCOMES

• Understood how to create rigidwall,interfaces and apply initial velocity.
• Understood how to check mass and centre of gravity and how to add additional masses.
• Understood how to do model check.
• Understood how to create crossections,accelerometers and intrusions.

CONCLUSIONS

• The crossectional forces are decreases when it came from bumper to pillar.Because the elements absorbs energy.Thus reduces the forces.
• As we seen from the accelerometer graph it first increases,reaches the peak then decreases.
• The internal energy also increases because of absorbing energy.
• The energy error must be -15% - 2%.Energy error first increases then decreases and going to negative.Because as the displacement continues it prouces a repulsive force to prevent more penetration.
• Maximum intrusion came upto 700 mm.That means any person within 700mm inside the car will cause death.
• Maximum acceleration is around 2.5 mm/mS^2.