Assignment 6-Frontal Crash Simulation Challenge

OBJECTIVE :

• Analysis Of the Frontal Crash of the Neon car Model .
• Making the Model Run properly using the Various Kinematic and Loading Conditions.
• Checking for the Error and debuging them for proper runing of the Model .
• Simulating the full model in Hyperview .
• Analysing the various Energy Graphs For Better study of the Crash Simulation .

Theory : 

  Body in white (BIW) is the stage in Automobile Manufacturing in which a car body's frame has been joined together, that is before painting and before the motor, chassis sub-assemblies, or trim (glass, door locks/handles, seats, upholstery, electronics, etc.) have been integrated into the structure. Assembly involves different techniques such asWelding (spot, MIG/MAG),Rivating ,  Clinching , Bonding and laser Brazing .

 

 

Parts :

A piller : Front Most support to the Roof .

B piller : Second most support to the Roof .

C piller : It is rear most support ; In case of the 2 seating system it wiil be 3rd one .

D piller : It is Forth support to the roof can be find the near rea side of quater panel .

Roof Header : Structural member above the windshield at the  juncture with the forward edge of the roof panel .

Shotgun : Main structural Member of the BIW which absorb Crash energy , support battery and other parts , Transfer shock load from shock tower to Body .

Bumper : A horizontal bar Fixed at front and back side of the vehicle to reduce the damage in collision .

Rail : Located just behind the Bumper and absorb the crash energy after the Bumper .

Section : It is representation of the cross members of the vehicle .

Intrusion : Sudden Impact on the Body

Procedure :

• The Neon Model is imported by setting the user profile For Radioss .

• The Unit system here we are following the KN , mm , ms , Kg , which can be seen from the Material parameters .

• Here we can see the extra Type 7 interfaces which will cause the simulation to run very slowly .
• Hence , I have deleted all the interfaces for each surface or part .
• Created only one Type 7 interface for all the Surface or parts .
• All the parameters are changed to the recomonded parameters .
• Changed  Istf = 4 ,
• Igap = 3 ,
• Idel  = 2 ,
• Fscale_gap = 0.8 ,
• Stmin = 1 KN/mm^2,
• % mesh_size = 0.4 ( default )
• Fric. = 0.2 ,
• Gapmin = 0.5 ,
• Iactiv = 6 ,
• Iform = 2 .
• This parameter can be seen below as ,

• Type 7 Interface can not tackle the edge to edge contact .
• For that Type 11 interface is also created to overcome the Edge to Edge Contacts .
• All the parameters are changedto the recommonded parameters .

•  Now Checking is done for initial Penetrations and Intersections .
• This is done by Penetration checking Tool as ,

• For Fixing this Penetrations and Intersections , The Automatic Penetration / Intersection Fix Tool .
• Then Again initial penetration and the intersection is checked , as i have fixed the penetration by above method , which can be seen below .
• The Message with 0 penetration and the intersection can be seen in below image at left down side corner .

• Now Rigid wall is created with the Froction value of the 0.1 .
• Dsearch = 1000 ,

• After creating the Rigid Wall , i have cheched for the Center of Gravity .
• Initially this center of Gravity is present near and just below the dashbourd .

• A vehicle’s center of gravity, or CG, is the theoretical point where the sum of all of the masses of each of its individual components effectively act .
• Lower location of the Center of Gravity point is better from a handling standpoint, as it reduces weight transfer during cornering and braking, and it also reduces the propensity to roll over.
• The ideal location of Center of Gravity point  should be below or near the drivers seat .
• For shifting this COG point towards the Idial Location i have added the Mass of Total mass of the 300 kg at rear end of the BIW body as shown in Below imgaes .
  

 

• For this Initially group of node is created at both left and right side seat's location .
• This using the ADMAS Tool , The mass type = 1 is selected .
• The Mass of 300 Kg will evenly distributed on each node .
• This Mass adding is helped lot for shifting the Center of Gravity point's Location .
• But In Hypermesh we can not see the Center of Gravity point directly .
• HyperMesh only show the Coordinates of the COG in X , Y and in Z direction .
• Using this Values , i have created the Teperary node as , 

• To move this COG point near the Cross rail by small distance , to match with the Ideal location .The mass of Hand Brake is added at the cross rail location .
• And the Weight is of Rear Console also added , which is distributed evenly over all selected nodes .
• which moved the COG point by little distance .

• Now Initial velocity is applied to all the parts by creating the INVEL card , in which the Type choosed as TRA = Translational Material Velocity .
• As we are folowing the milimeter and milisecond unit , hence initial velocity of 35 mph is converted to 0.01564694 milimeter/milisecond .
• For Skew id , newly created SKew System is used .

• While runing the simulation there was an Error Thrown regarding the Initial Velocity which can be seen below .
• This Error is resolve By defining the Group of Nodes .

• Now Model checker is used to check the model's Quality .
• Now here we don't Got any Errors , but the Warnings only we got .
• This warnings just can be ignored for this model .

• Now time step of 0.5 microsecond is given .
• This time step is given in ENGNINE_KEWORDS - DT - DT_NODA CARD .
• Here CST ( Constant Step Time ) , this is used to maintain the COnstant time step my Adding the mass to model .
• HEre Tscale is Given as 0.67 and Tmin = 0.5 microsecond .

• Simulation run time is kept as 80 milisecond .

 Output Request :

• For requesting the Sectional Forces in Rail Indicated Node Point 174247 at both side Left and Right , Group of Node is defined at Indicated node location and Using N1 , N2 , N3 points Reference is Defined as ,

• Axial Force received on the rails from Bumper are difined by creating the Type 7 Contact interface between the Bumper and the rails on the both side left and Right side .
• bumper difined as Slave Nodes and rains nodes are defined as master nodes as ,

• Shotgun Cross sectional Forces are Defined Using Group of the nodes at appropriate location at both location left And Right , using Points N1 , N2 and N3 reference is defined as ,

• For getting the Force at A piller , Section is created unig the group of the nodes and with the N1 , N2 and N3 reference is also defined on the Both sides as,

• For getting the Accelerometer Curve , i have created the accelerometer at the Rocker part of B piller on both side as ,

• For getting this accelerometer output in Time history , TH card is also Created ,

•  Intrusion at Node 66695 and the 66244 created with the Reference of New skew system as ,

Now Model is ready to run :

• Now Model is made to run In Radioss Solver and Simulated using the HyperView .
• The Energies plots are plotted using the HyperGraph2D .

 

 Results :

Energies :

• From graph is can be seen that the Kinetic Energy is High at Starting Of crash and decrease after the crash happens .
• The Kinetice Energy decreases with increase in the internal energy .
• This kinetic Energy is get converted into the Internal Energy .

 

• The Hourglass energy is in the range of the 5 % of the Total Energy .
• This hourglass energy is much stabalized as we have improved the shell properties to the recommonded .
• The Total energy is Almost Constant , which is Good Sign of Energies Balance .

Setion forces at Given Node:

At 174247 left :

 At Right Side :

 

• Maximum Force Right side of the indicated node location is observed 21.147KN and on Left side is 6.67 KN .
• More Force observed on right side is because of the Weight Distribution , as force directly propertional to the Mass .
• Hence more force is travelled through the right side .

Axial Forces at the Rails :

•  The axial forces are the force Which are get transfer from the Bumper to the Rails .
• When Crash happens , Force generated into the Bumper are get transfer to the Rails and This forces are firther transfed to the Next sections and parts .
• The maximum force we are getting at the rails form bumper is 166.217 KN . 

 

 Shotgun Forces :

Left :                                                                                        Right :

• The Forces in shotgun section are come from the frontal rails , which are then transfer further and Some part of the Absorbed here .
• The maximum force is passing through the left Shotgun section is 19.0304 KN than the right Shotgun section is 12.498 KN .
• Here the Less Force is absorbed than the rails and other frontal parts .
• Uneven distribution of the Force passing through the Shotgun section is because of the Uneven distribution of the Mass .

A piller Forces :

Left Piller :                                                                                        Right Piller :

• The Residual forces from the Frontal Parts are absorbed in the A piller Section .
• The Forces Passing through the Left and right A pillers are 3.32158 KN and 2.36451 KN .
• The Forces through the A piller Decides the damage to the Occupants in Vehicles .
• More the Force More will be the damage to Occupants .

Intrusion At Dashboard :

• Intrusion means the sudden change in space located for the feet of the occupants in vehilce .
• This Intrusion Matters the most in term of the Occupant's saftey .

• Intrusion at 1st indicated nodes is _975.009 mm and at 2nd node is -923.555 mm .
• The Negative sign indicates the intrusion happening in the Negative X-axis direction .

Errors :

After assigning the Condition and creating the sections , while analysing the model using the Radioss Solver .

There was an Error thrown , regarding the Initial velocity That the , there is no group of nodes was defined .

This Error is rectifed by defining the Group of the nodes  .

And again Model is analysed by the Radioss and it analysed Any Errors but with some wanrnins  which can be ignored .

Conclusions :

• For proper crash results , the Mass distributions Matters the most .
• The forces from the bumper are transfered to the further parts and distributed over other parts depending upon the BIW structure of the vehicles .
• most of the Forces are absorbed at the Bumper level after the crash of the vehicle .
• Followed by the Rails .
• This Rails and followed parts are designed in such way that they should absorb most of all the forces resulted due to the Crash of the vehicle.
• The Intrusion at the Dashboard should be less as possible .
• This Intrusion plays an important roles in the Occupants Saftey.
• More the forces passes trough the section / parts from fornt side to back side More will be the dangerous for the Occupants .