Assignment 7
ASSIGNMENT-7
VIRTUAL SIDE CRASH ANALYSIS OF NEON BIW {Body In White}
OBJECTIVE:
The main objective of SIDE crash analysis of neon BIW is to know how much Sectional force is received in the cross member of neon BIW. And to know about intrusions of a model, as well as peak velocity of inner node of the door. The other objective of frontal crash analysis of neon BIW is to create a global contact interfaces, CYLINDRICAL rigid wall, add the masses to reach a target weight of 700kg while getting COG [ CENTRE OF GRAVITY] about the required range, initial velocity of 35 mph. Finally creating cross sections, as well as intrusions.
All this pre-processing process are carried out in hyper mesh, simulation is performed by using Radioss, and Hyper graph is used to plot cross sectional forces received in cross member, intrusions on the B-PILLAR, HINGE PILLAR, FUEL TANK REGION, and peak velocity at node ID 337773.
CASE SETUP AND EXECUTION:
STEP-1:
CHECK THE UNIT SYSTEM: WE HAVE CHECKED THE UNIT SYSTEM IN THE neon_front_0000.rad file AND WE FOLLOWED Kg mm ms throughout the process.
STEP-2:
IMPORTING THE MODEL:
The model is imported into to hyper mesh, by click on import solver deck- search the neon_side_reduced_0000.rad file and click on import.
FIG: IMPORTING THE MODEL
FIG: IMPORTING THE MODEL
STEP-3: CREATING INTERFACE:
Create an appropriate interface with friction 0.2 and recommended parameters.
Already a contact is defined in the model we have to delete that interface and to create a new interface [TYPE7] with recommended parameters.
Important Interface Parameters:
Igap = Determines how the size of the gap is calculated
Gapmin = Minimum gap for activation of interface
Inacti = Action to take if initial penetrations exist
Istf = Affects how the stiffness of the interface is calculated
Iform = Friction formulation
Stmin = Minimum stiffness to use in the interface
Idel = Update For Deleted Elements Due To Failure
The recommended contact parameters for interface Type 7:
Istf = 4
Igap = 2
Fscale Gap = 0.8
INACTI = 6
Gap_min = 0.5
Fric = 0.2
Iform = 2
STEP-4:
Now run the penetrations check and
Make sure of no penetrations and intersections. if there is any penetrations correct it or simply use the gapmin value to reduce the penetrations.
Rigid body issues, if any issues make them corrected, by using hyper crash.
STEP-5
CYLINDRICAL RIGID WALL CREATION:
An obstacle like infinite CYLINDRICAL rigid wall is created at left side of the model with some parameters like friction = 0.1, Dsearch as 500 and diameter as 254.
A cylindrical rigid wall is created by clicking on solver - right click - create -rigid wall - cylinder - ok. then a dialogue box will open and assign the rquired values.
FIG: CYLINDRICAL RIGID WALL
STEP-6:
ADDED MASS:
Initially the model has a weight of 166.3076 kg. We have to add the mass to reach a target weight of 700kg to get the COG about the required range. We have to add the mass at the floor of the BIW in order to get the COG at required range.
A wide variety of mass type options are available to add the mass, we have to choose the option-1 for better results.
FIG: MASS IS ADDED TO THE CROSS MEMBERS IN ORDER TO BRING THE CG ABOUT REQUIRED RANGE
STEP-7
INITIAL VELOCITY:
We have to create a initial velocity in order to perform the crash. Generally, we have to give a initial velocity of 35 mph, which is a standard value according to the crash standards. As we have following the kg mm ms units we have to change the 35 mph to required value.
we know that,
1 mile = 1.609344 km
1 km = 1000m
1m = 1000 mm
1 sec = 1000 ms
Based on this value we changed the value from 35mph to 15.6464 mm/ms.
We have created an initial velocity with 15.6464mm/ms, in Vy-direction which is perpendicular to the cylindrical rigid wall.
STEP-8
TIME STEP: 0.5 TO 0.1 micro seconds.
We have to create a time step in between 0.5ms to 0.1ms. And we have created the respected values as shown below. Run time as 80ms and Tfreq as 5ms. Use the model checker to ensure good quality.
STEP-9
OUT PUT REQUESTS:
We have to create the cross sections at cross members of BIW in order to get cross sectional forces, intrusions to know the displacement of the B-PILLAR, HINGE PILLAR, FUEL TANK REGION, and peak velocity at node ID 337773.
CROSS SECTIONS CREATION:
We have to create the cross sections to know the forces acting on that particular sections. we have to create sections on the cross members of BIW model.
Go to solver - right click - create - sec - sec - ok. Then a dialogue box will be open.
Before creating the cross sections we have to create a movable skew at the respected location and add that skew in this dialogue box. Then select the elements around that skew in at least two columns of elements through out all sides as shown below. Select the grshel_id if we got the quad element at respected skew, and select the grtria_id if we got the tria element at respected skew. Assign some values to that card such as ISAVE as 0, deltaT as 0.1 alpha as 0.65 and Iframe as 12. perform the same method for other components and create the required cross sections.
FIG: CREATING CROSS SECTIONS.
After creating all cross sections, we have to create the intrusions.
STEP-10
CREATING INTRUSIONS:
We have to create an intrusions on the B-PILLAR at a node location of 123211, HINGE PILLAR at a node location of 123321, FUEL TANK REGION at a node location of 123362, to know the displacement of the particular wall into the occupant area. For this we have to create a fixed skew and make the respected node numbers in one position.
STEP-11
Peak velocity at node ID 337773:
We have to know the peak velocity of inner node of the door, for that we have to create a node reference, by using TH Node.The below figure shows the all-out put requests.
FIG: WITH ALL OUT PUT REQUESTS.
STEP-12
CREATING OUTPUT BLOCKS: [TIME HISTORY]
Finally we have to delete the already requested output blocks and create a new out put blocks for cross sections, intrusion at 123321, 123211, 123362 and peak velocity.
STEP-13
RUN THE SIMULATION: [BY USING RADIOSS AS SOLVER]
After creating all required out puts in hyper mesh, we have to run the simulartion by using Radioss [solver]. keep the export options as all, run options as analysis, run number as 1, options as -nt 4.
The below figures show the simulation files.
From the above figures we got,
Elapsed time = 1923.78 s
Energy error = -2.6%
Mass erorr = 0.1515E-01
TOTAL NUMBER OF CYCLES = 80001
WE GOT NORMAL TERMINATION
ENERGY ERROR: Basically energy error must be negative and decreasing.The Error must be less than 15% at the end of computation, as per the condition. If the error is below 15% than the results could be acceptable.
So from the above figure, at the end of computation the energy error is -2.6% and mass error is 0.1515E-01. As per the condition the energy error is -2.6% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
SIMULATION:
PLOTING GRAPHS:
SECTIONAL FORCE IN THE CH CBN SEAT REINF FT COMPONENT:
From the above plot we can see that the maximum force in THE CH CBN SEAT REINF FT is 2.32KN, which is around the 68ms.
SECTIONAL FORCE IN THE THE CH RAILS U MID COMPONENT:
From the above plot we can see that the maximum force in THE CH RAILS U MID is 4.85KN, which is around the 34ms.
Intrusions at 123321, 123211, 123362
The purpose of intrusion to know the displacement of the particular wall into the occupant area.
INTRUSION ON HINGE PILLAR AT NODE 123321:
Before collision the distance between two point is 1311.042 mm.
After collision the distance between two point is 821.781mm
From the above plot the intrusion of Dashboard is 489.261mm.
INTRUSION ON B-PILLAR AT NODE 123211:
Before collision the distance between two point is 1308.091mm.
After collision the distance between two point is 502.110mm
From the above plot the intrusion of Dashboard is 808.981mm.
INTRUSION ON FUEL TANK REGION AT NODE 123362:
Before collision the distance between two point is 1309.662 mm.
After collision the distance between two point is 429.516 mm.
From the above plot the intrusion of Dashboard is 880.146mm.
PEAK VELOCITY: THE BELOW GRAPH SHOW THE PEAK VELOCITY AT AROUND 17.2 mm/ms.
GLOBAL VARIABLES:
RESULT:
CONCLUSION:
When a collison is take place, a reaction force will generate from the cylindrical rigid wall, which is generally called as kinetic energy. this energy has huge amount of impact. if it is taken by the passenger There is chance of injury. In order to over come this, the energy should be absorbed by the car component itself. From the plot we can see that there is a increase in internal energy and decrease in kinetic energy. By this we can say that the energy is absorbed by the components. The total energy remains constant. So the kinetic energy is converted into internal energy.
The contact energy remains constant due to implementation of recommended parameters.
The hour glass energy is also remains constant due to use of recommended parameters.
From the above intrusion we had noticed is, the intrusion at fuel tank region is high, when compared to others. In order to reduce the intrusion at fuel tank region we can change the material, which have good strength or we can modify the design if required.
HOWEVER SOME SORT OF ENERGY WILL BE IMPACT BY THE PASSENGER IN A REAL LIFE CRASH SENARIO.
FINALLY WHAT WE CONCLUDE IS THE CROSS MEMBER {CH RAILS U MID} WHICH IS NEARER TO THE IMPACT POLE HAD RECEIVED MORE ENERGY WHEN COMPARED TO OTHER CROSS MEMBER.
DIFFICULTIES FACED: IN THIS ASSIGNMENT WE HAD FACED SOME DIFFICULTIES WHILE CREATING THE CYLINDRICAL RIGID WALL. THE WALL WILL CHANGES ITS POSITION WHEN WE MAKE A SIMULATION. FINALLY WE KEPT THE POLE AT RIGHT LOCATION AND PERFORMED THE PROJECT.
LINK: https://drive.google.com/drive/folders/1ycvK50QelJ9leiC2GpXEMb51tQOa2ZuV?usp=sharing