Assignment 6-Frontal Crash Simulation Challenge
The main aim is to perfrom frontal analysis in the neon model with the recommended parameter and output requests.
. Check unit system and either follow[mg mm s] or [kg mm ms]
. Create opproprite interface, friction 0.2 and recommeneded 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 modell 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.
PROCEDURE:-
Generally the procedure for crash involves
1). Pre-processing.
2). Processor.
3). Post-processing.
Pre-processing:-
The unit system is confirmed from the starter file and throughout this analysis the carried out unit convention is kg mm ms.
unit system
INTERSECTION & PENETRATION CHECK>
The intersection and penetration ckeck is made to get rid of result get affected open contact interface in hypercrash > select check
penetration check option.
check intersection and penetration
INITIAL VELOCITY:-
For this model an initial velocity of 15.6464 mm/ms (35mph) is applied to the car model to initial the crash sceneraio. right click on the tool bar inside solver deck and select initial velocity option under boundary condition it is applied in Vx direction perpendicular to rigid wall.
CONTACT INTERFACE:-
make connection with type 7 to repersent self contact with recommended parameter by deleting the already creeate 6 contacts friction for this conta ct is taken as 0.2 mm.
RIGID WALL:-
The rigid wall is create at the bumper section for representing the wall properties for the crash dsearch value is taken as 1000 mm with friction 0.1 mm to seearch for slave nodes.
MASS BALANCING:-
Initially the mass of the model is 188kg in order to represnt the scaled model into full car model, the mass is converterd to 700kg rigit click on the solver deck and create admas card to add mass to the model.
additionla mass of 51.2kg is added to reach nnpode as highighted so that full car model is reperesented and we hhave COG located near the driver seat as recommended.
BALANCING
The below image shown the full scale model i.e 700kg use Tool>mass details>mass only to check the imputed mass.
Before starting to run the simulation, it is necessary to check for error in the model. for this use Tool>Model checker>radioss elements.
PROCESSOR:-
the simulation ran for 80001 cycles. energy error is -1.3% which is acceptable mass error is 1.5% which is also less than 5% and is under control as per the simulation.
POST PROCESSING:-
Post processing involve plotting the results and analyzing then after the simulation has terminatted.
1). Create cross section in
. rail
. Shor gun
. fender
. A-Pillar
2). create accelerometer at the based of B-pillar.
3). Create intrusion near the dash wall to study the effects of force in the dash wall.
SECTIONAL FORCE:_
Create a frame which is movable at rail, shot gun, fender & A-Pillar to study the effect of force on them respectively.
select N19origin node), N2(axis direction), N3(plane at frame should be created).
select the highlighted elements for grap shell element node select proxessed button.
Select the frame create in the frame 1D for cross section. use delta as 0.1mm and alpha as 1.64mm. hance the necessary cross section create to analyse the effect of forces.
As soon as the car hit the rigid wall, its the shot gun which gats damaged heavily compare to other parts as per plot, shot gun left and shot gun right absorbs 5.8kn at 0.033 ms and 6.9kn at 0.38ms of force respectively and decrease
from the fender plots, we can infer that rigit fender absorbs maximum force compare to the left one .
Right fender - 6.8kn at 0.043ms
left fender - 3.7kn at 0.037ms
Initially the force remain zero at both the rails, and as soon as the car hits the barrier the energy absorbing capacity increase in both left and right rail. left rail absorbs more energy as pert the simulation. it plays important role, since the force is transfered to the pillars through the rail component.
left a pillar experience 1kn at .026 ms and is the highest force compared to right a pillar which experience 0.58kn at 0.053ms.
left a pillar experiences more force initially and then the force decrease at 0.033md ms and it increase upto 0.2kn.
At 0.33ms in right a pillar the force absorbing capacity increase upto 0.57kn.
At 66244 and 66695 node location, the intruded force is at its peak due to the absence of components of a car. if the component are present, they will absorb the force and the rest will be impacted on the dash wall.
ACCELEROMETER:-
The acceleometer is placed at the bottom of the both sides of the B-pillar to record the acceleraction at the bottom of B-pillar.
The accelerometer at the right side has high acceleration value( 10 mm/ms^at 0.043 ms ) and descreases.
for left accelerometer, maximum accelkerration value comes st 0.038 ms for a volue of 1mm/ms^2 and taken decrease and increase.
the left accelerometer placed at the left side has high acceleration compared to right side.
CONCULSION:-
Thus frontal crash has been analyzed on the neon model and the observation are analyzed and recorded on studying the result the force absorbed are high in the order from shotgun, rail, fender and A-pillar respectively. thses result are not most accurate ebventhrough the mass is balanced & COG is located at its exact position. if we want more accurate it is adviced to use to use full sacle neon model for the simulation.