Assignment 6-Frontal Crash Simulation Challenge
AIM:
To create a setup for frontal crash of car BIW and request for Time History plots.
OBJECTIVE:
1.Check unit system and either follow[Mg mm s] or [Kg mm ms].
2.Create appropriate interface ,friction 0.2 and recommended parameters.
3.Make sure of no penetrations and intersection.
4.Correct rigid bodies if any issues.
5.Create rigid wall with friction 0.1.
6.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.
7.Initial velocity 35 mph.
8.Use model checker to ensure good quality.
9.Time-step :0.5 to 0.1 microseconds.
10.Run 80 ms.
OUTPUT REQUESTS:
1.Sectional force in the rails at location of indicated node 174247.
2.Axial force received on the rails from bumper.
3.Shotgun cross sectional forces.
4.A pillar cross section.
5.Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).
6.Intrusions on the dash wall 66695,66244.
THEORY:
A crash simulation is a virtual recreation of a destructive crash test of a car using a computer simulation on order to examine the level of safety of the car and its occupants.
It permits optimizaion of the design before a real prototype of the car has been manufactured. Using simulation problems can be solved.
The great flexibility of printed output and graphical display enables dessigners to solve some problems that would been nearly impossible without the help of a computer.
During a crash simulation the kinetic energy or energy of motion that a vehicle has before the impact is tranformed into deformation energy mostly by plastic deformation of the car body material at the end of impact.
Crash simulation are used to investigate the saftey of the car occupants during impacts on the front end structure of the car in a frontal impact.
PROCEDURE:
1.Import the given model.
CASE-1 (Check unit system and either follow[Mg mm s] or [Kg mm ms]):
1.Goto model browser > Cards > Begin Card > Check for the units.
2.The unit system followed in Kg-mm-ms.
CASE-2 (Create appropriate interface ,friction 0.2 and recommended parameters):
1.Type 7 contact is used with all recommended properties and with friction value of 0.2.
2.For Slave and Master all 74 components is selected.
CASE-3 (Make sure of no penetrations and intersection):
1.Goto Tools > Penetration Check > Select check types as intersections and Penetrions > Select all components > Check.
2.The output result is : All interface check is completed:0 collisions found.
CASE-4 (Correct rigid bodies if any issues):
1.As there is no penetrations and intersecions there is no isses with rigid bodies.
CASE-5 (Create rigid wall with friction 0.1):
1.Goto Solver Deck > Right click > Rwall > plane.
2.Select any node on the bumper and change the x-coordinate such that a gap is maintained.
3.Say that the sliding friction with value of 0.1.
The model with rigid wall is shown below:
CASE -6 (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):
1.Check the mass and COG point.
2.Goto Tools > Mass Details > Mass,COG and Inertia.
3.Intial mass is 180kgs and cog point is not desirable.
4.Add mass to get 700 kgs and desirable COG point.
5.Goto Solverdeck > Right click > ADMAS > Select the nodes on which the mass should act > provide value of mass.
CASE-7 (Initial velocity 35 mph):
1. Goto Solverdeck > Right click > Create Inivel > Select all components and provide the value of velocity.
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CASE-8 (Time-step :0.5 to 0.1 microseconds):
1.Goto Model Browser > Cards > Anim_Dt > Tfreq = 5.
CASE-9 (Run 80 ms):
1.Goto Model browser > Cards > Eng_Run > Tstop = 80.
OUTPUT REQUESTS:
CASE-1:
1.Creating frames at each cross-section where forces are to calculated.
2.Goto Solverdeck > Right click > Create Frame > Select N1,N2,N3 such that N1 and N2 are making X-axis and N3 X-Y plane.
3.Create section at which cross-sectional forces are to determined.
3.Isolate the respextive co,ponenet and create the section by selecting the respective elements and choose the respective frame in the frame id and set iframe = 12, the Cog of the section.
4.The same procedure is done for Rail component, Shotgun, Bumper Rail and A-Pillar regions.
CASE-2:
1.Create Accelerometer by right click in the model browser.
2.Goto solver deck > ACCEL > Select the node and provide. Fcut = 1.9.
CASE-3: (Intrusions on the Dash Wall 66695 , 6624)
1.Create the Skew on Seat connector frame on either end.
2.Goto Output block > Name it and select the node by node id.
For Intrusion 1:
For Intrusion 2:
CASE-4: (Model Checker):
1.We are using model checker to ensure good quality.
2.There are no errors in the model so we further move to next process simulation.
OUTPUT:
1.Goto Analysis > RADIOSS > Save the file > Include connectors > in Option -nt 4 > Prove the number of threads in options > Run.
2.The RADIOSS is run and it complete it job.
3.Open Hyper view >Import the h3d file.
1.THE VON-MISES STRESS:
2.THE DISPLACEMENT CONTOUR:
4.The Energy Error, Mass Error, Internal, Kinetic Energy from 0.001_out file.
5.The energy error is -1.2% and mass error is 0.03% which is acceptable.
6.The mass error is due to adding of mass for maintaing the time step value.
7.The maximum kinetic energy = 86970 J and Minimum Kinetic energy = 46560 J.
8.The maximum internal energy = 38140J and Minimum Internal energy = 146.5 J.
9.We can see at the start of simulation of internal energy is minimum and Kinetic energy is max.
10.As the deformation is taking place internal energy increases and kinetic energy decreases thereby maintaing the total energy as constant.
GRAPH:
1.Goto Hypergraph_2D > Import the T01 files.
2.Hourglass energy is less than 4% of total energy and is stablized by using the recommended properties.
3.We can see at the start of simulation the internal energy is minimum and K.E is max, as the deformation is taking place Internal energy increases and Kinetic Energy decreases thereby maintaing the total energy as constant.
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SECTIONAL FORCES ON THE BUMPER RAIL BRACKET:
1.The maximum force on the left bracket = 14kN.
2.The maximum force on the right bracket = 12kN.
3.Initially, there is no axial force is transmitted from bumper to rail. Once the vehicle hits the rigid wall, bumper starts deforming and transmits the strain energy to the rail section.
ON RAIL COMPONENT:
1.Maximum cross-section force on the left rail = 5.5KN.
2.Maximum cross-section force on the right rail = 9.3KN.
3.The force acting on the rail is transmitted by the bumper. The deformation takes place by rail and is transformed to other components thereby decreasing the c/s force with respect to time.
On Shotgun Component:
1.The maximum cross-section force on the left shotgun = 12KN.
2.The maximum cross-section force on the right shotgun = 9.3KN.
3.The force that occure dat the shotgun is the force transmitted from the rail section.
4.The force propogation on either ends are different causing different deformation.
5.The compressive forces reaches the maximum value it starts to deform rapidly. Therefore, the compressive force is decresing as reffered.
6.As crash happens continuously the shotgun will come into contact with rigid. The rigid wall also exerts the force directly on the shotgun and there is an increases in sectional force.
ON A-PILLAR COMPONENT:
1.The maximum force at the left cross-section of A-Pillar = 2.8KN/mm.
2.The maximum force at the right cross-section of A-Pillar = 2.3KN/mm.
3.When crash happens there will be some amount of force i.e., transmitted on to both ends of A-Pillar.
4.These forces are transmitted from the Rail component and shotgun component. Therefore, the force at A-Pillar is less than the Rail and Shotgun Component.
5.The force flowing on either ends are not equal and deformations are also not the same.
6.When the compressive force between the wall and car is maximum, the rail and shotgun will get in contact with rigid wall which causes the shotgun and rail to exert more force.
7.The force then propogates through A-Pillar and hence the force reaching the A-Pillar is increasing again.
ACCELEROMETER:
ACCELEROMETER-1:
ACCELEROMETER-2:
1.Accelerometer is placed on the either ends on rocker of B-Pillar.
2.From this, we can see that initially the acceleration is almost constant before crash, once car hit the rigid wall with initial velocity, the acc of vehicle during crash is not constant across the structure.
3.The front of the vehicle slows down immediatly as it hits the rigid wall while the rest structure deccelarates at slower rate.
4.As seen there is sudden increase because of vibration that occur during crash with respect to time point where accelerometer is place.
5.The maximum acceleration at left = 3.2mm/s^2.
6.The maximum acceleration at right = 3.25mm/s^2.
INTRUSION 66695 AND 66244:
1.66695:
2.66244:
1.To check the intrusion of the dashwall at the particular nodes, we have created the skew and selected the particular node.
2.The intrusion at this particular node is calculated in order to check whether crash will result in the saftey of driver due to deformation the occured in the component.
3.On node 66695, The intrusion is 835mm and On node 66244 is 815mm.
6.This elongation reffered to that what extent the foot pedal will mov once the crash happens.
OBSERVATION:
1.Thus the set up of a frontal crash test is performed.
2.Thus the create of a rigid wall, sectional forces is performed.
3.Thus the forces are distributed during the Frontal crash is performed.
4.Thus the Check energy, mass and momentum balance is performed.
RESULT:
1.Thus the graphical results were plotted for all test cases.
2.Thus the simulation it is observed that there is minimum of deformation in the cabin, and minimum intrusion was found in the drivers seat area.