Neon Frontal Crash Analysis of BIW model.
OBJECTIVE:
Objective of this project is to check and create the properties for a neon frontal crash model.
These are the recommended checks performed in the model:-
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.Timestep :0.5 to 0.1 microseconds.
10.Run 80ms.
SOME DEFINITIONS:
Body in white(BIW):-
Body in white (BIW) refers to the stage in the automobile manufacturing in which a car body's components have been joined together, using one or a combination of different techniques: welding (spot, MIG/MAG), riveting, clinching, bonding, laser brazing etc.
Center of gravity:-
The center of gravity of any vehicle is the point that sums up the vehicle’s mass in one central point. To put it simply, it is the average location of the weight of an object.
Critical Time step:-
The time needed for information (stress,pressure,wave) to cross the smallest distance in an element is known as critical time step. An explit analysis can be called stable only if the current time step is bigger than the critical time step in the simulation.
1. Check unit system and either follow[Mg mm s] or [Kg mm ms].
The unit system is checked in both Radioss starter file and in the Hypercrash model. The selected unit system is:- kg, mm, ms.
In Radioss starter i.e neon_front_0000.rad file-->
In Hypercrash model---->
2. Create appropriate interface ,friction 0.2 and recommended parameters.
By necessity it was observed that, the TYPE 7 interface would be best suited for the corresponding model as it has high accuracy for describing self-contact and buckling.
so TYPE 7 interface with its all recommended parameters are created.
3. Make sure of no penetrations and intersection.
To check the presence of penetration and intersection in the model we need to open the "Quality" in Hypercrash.
As in the present model from the refered image, no intersection or penetration is present. So we can further proceed.
4. Correct rigid bodies if any issues.
After reviewing the model ,no issues is seen.
5. Create rigid wall with friction 0.1.
As recommended the rigid wall with friction 0.1 is created with following properties:
Created rigid wall
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.
From the given model the total weight of the model is 188.4254437 kg.
And the C.g is also very near to the dashboard which is not good sign for the seafty of the car.
To balance the COG of the car which should lie below to the driver's seat, and also to achieve the target weight i.e 700 kg, required weight is added.
Required weight =Target weight - Available weight of the model
Required weight =700kg-188.4254437kg =511.5745563kg
The required weight is added to these yellow nodes, to achive the target weight and COG of the car.
New COG after weight balancing
7. Initial velocity 35 mph.
Initial velocity card is created with 15.6464 mm/sec in the positive x-direction.
Accelarometer is installed on the B-PILLAR with the sensor.
8. Use model checker to ensure good quality.
After setting all the parameter, checked the mode wheather all the function and parameters assigned properly or not. To check it clicked on the Quality option--->Model checker-->Run
9. Time-step 0.5 to 0.1 ms:-
To get graphs plot for diffrent required results in Time history file(T01) ,In control card --->ANIM DT--> set up the t=0.5ms to save data in every 0.5 ms.
10. Run:-
To set the Run time , Control card--->RUN-NAME_NUMBER_LETTER--->final time for run (80 ms).
SIMULATION Results (RADIOSS):-
Energy error= -1.7%
Mass error= 0.2923E-01
Animatio Of the crash model:-
OUTPUT REQUEST:
I)Sectional force in the rails at location of indicated node 174542.
Maximum sectional force =5.8727 kN at t= 53 ms and at t= 79.5 the force is 1.25891 kN, can be seen in the graph.
II)Axial force received on the rails from the bumper.
For Left side
Maximum axial force is 7.33052 KN at t=38 ms. and at the end it is 6.82049 kN.
For Right side
Maximum axial force is 5.49816 KN at t=49.5 ms. and at the end it is 1.77244 kN.
III)Shotgun cross sectional forces.
For Left side
Maximum Sectional force is 1.5325 KN at t=47 ms. and at the end it is 1.03511 kN.
For Right side
Maximum sectional force is 1.58351 KN at t=36.5 ms. and at the end it is 0.846501 kN.
IV) A-Pillar cross section.
For Left side
Maximum Sectional force is 3.06702 KN at t=34 ms. and at the end it is 2.69214 kN.
For Right side
Maximum sectional force is 2.86682 KN at t=35 ms. and at the end it is 2.34832 kN.
v)Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).
For Left side
Maximum accelation is 0.404461 mm/sec2 at t=59.5 ms. and at the end it is 0.0467115 mm/sec2.
For Right side
Maximum accelation is 0.32509 mm/sec2 at t=48 ms. and at the end it is 0.104571 mm/sec2.
VI)Intrusions on the dash wall 66695,66244.
Intrusion on Acceleration padel i.e on node 66695
During the crash,
Intrution=768-598=170 mm
Intrusion on Brake padel i.e on node 66244
During the crash,
Intrution=782-625=157 mm
VII) Different Energy plots:-
Results and Disscussion:
i)On the recommended node,from the graph it is clearly seen that at the starting point when the impact was just started at t=0, the amount of force was nearly minimum but after few ms later it suddenly goes up and at the end of simulation again it is nearly to minimum.
ii)From the graph and animation file it is can be seen that on the left side of the BIW model, more deformation is happening as compare to the right side.
iii)Accelerometer is used to determine the acceleration on the B-pillar rocker. the obtained graph results are acceptable.
iv)Energy graphs looks good as there is no sudden jump or fall is seen.
v)Energy error is -1.7 and the mass error is 2.923% , which are acceptable.
CONCLUSION:
All the requested outputs for Ne"on frontal crash" are successfully obtained. and the required output files and graphs are also stored separatly.