Assignment 7-Side Pole Crash Simulation Challenge

Aim :

To create a side pole crash analysis on Neon car model using hypermesh and radioss solver.

Objectieve :

1. Import the neon car model to the hypermesh.

2. Create a circular rigidwall and type7 contact interface in the model.

3. Create intial velocity, intrusion cards and crossection cards using frame and skew.

4. Change the engine card values and check the solver deck before solving.

5. Extract the results using hyperview and hypergraph.

Theory :

Why side pole test is required?

Some side impacts involve a vehicle travelling sideways into rigid roadside objects such as trees or poles. Often this is the result of a loss of control on the part of the driver, owing to speeding, misjudgement of a corner or because of a skid in slippery conditions. Such accidents are severe and the frequency of death or serious injury is high.

Process for side pole crash :

A car is propelled sideways at 32 km/h against a rigid, narrow pole. The car is placed at right angles to the direction of motion, at a small angle away from the perpendicular. Where a vehicle is equipped with a centre airbag to protect against the front seat occupants hitting each other, two average male side impact dummies are placed in the front seats. Where there is no centre airbag, single dummy is placed on the driver’s seat.

This is a very severe test of a car’s ability to protect the driver’s head. As the loading on the car is so localised, deformation can be very high and the pole can penetrate deeply into the passenger compartment. Without effective protection, the pole would strike the head resulting in serious injuries. Head protection airbags – often curtain airbags mounted above the side windows but sometimes seat-mounted thorax/head airbags – have become a common solution but great care is needed to ensure effective performance of such devices.

Side Pole Test Condition :

The test vehicle and the pole are shown in the impact configuration at t = 0 .
During towing and at impact, the following conditions must be met:

A. The pole shall remain stationary at impact and shall have a diameter of 254 mm ± 3 mm
(10 inches).

B. The vehicle (or pole) shall be adjusted for proper alignment such that a
vertical plane passing through the three-dimensional center of gravity of the head of the
dummy forms an angle of 75o with the vehicle’s longitudinal centerline.

C. The test vehicle shall be towed sideways, at the specified test speed, toward the
stationary pole so that its line of forward motion forms an angle of 75° ± 3° (for left side
impact) with the vehicle’s longitudinal centerline.

D. The test vehicle’s velocity shall be constant (essentially having zero acceleration or
deceleration) for a minimum of the last 1.5 meters of travel before impact.

E. The vehicle’s impact speed shall be 32.20 km/h ± 0.80 km/h.

F. At impact, the test vehicle’s vertical impact reference line shall be aligned with the
centerline of the pole ± 38 mm (± 1.5 in) horizontally.

Post test measurements :

Dummy Contact points :

Prior to removing the test dummy from the vehicle, observe where dummy body parts made
contact with the vehicle’s door, interior components, other body parts, the rigid pole, and air bags,
as indicated by chalk markings transferred to the contacted surfaces. Where applicable, confirm
contact locations by using high speed video analysi. If no contact occurred for a particular body region, indicate as “No contact”.

Impact Point :

Measure the horizontal distance from the center of the impact point (caused by the cement tack
or other marker that was affixed to the pole pre-test) to the center of the target that was placed
along the vertical impact reference line in Section of this test procedure to denote the
point of initial contact. Record these distances on Data Sheet. Also, measure the distance
of the actual impact point aft of the front axle, calculate the horizontal offset.

Procedure :

1. Import the side door model of neon model to the hypermesh using import option.

After impoeting the file it already ha sthe material and property cards.

2. Now create the rigidwall using rwall card and define wall as circular and give friction and search distance to the cards.

3. Create a type 7 interface for the model and follow the below given values for recommended conditions for type 7.

4. Now create a intial velocity by invel card and give the velocity as 15.6464 in y direction and select the each component of the card.

5. Now create a crosssections on the both rail component using frame move option and apply this frame insection card.

6. After that we need to create a intrusions on the Hinge pillar, B pillar, and fuel tank, to do that first create a 3 skew ove cards on the parts and then go to ouputblock in model tab abd create three intrusion cards and select their respective skew system.

7. Now create a peak velocity on the front door inner side using skew system card i.e, same as above step.

8. Create a output card for the crossections and select the two crossection entities in this card.

9. Now change the time step in the engine dt brick, dt noda and dt inter and check engine run and anime dt.

10. Now export the file and run the file using radioss solver.

Results and Discussion :

1. Now radioss starts to solve the problem in a new tab and check frequently in this tab because when ever their is increase in energy and increasing in mass which is more than our requirements than stop the file using stop command. In our case energy error is -1.4% and mass added is 6.4% these are accepatable.

2. Now switch hyper mesh to hyper view and select the .h3d files of side pole crash test and open it and select the contour of displacement and vonmises stress and simulate the model.

From the simulation we can observe that maximum displacement is occured at the front bumper i.e, 1527 mm and remaining parts are prevented from more displacing to the pole.

From the simulation we can observe that most of stress is occured at B pillar and we can also observe that B pillar emboss structure is preventing the crash, this is the reason most of the biw parts has emboss structures which adds strength to the part. Maximum stress of the model is 0.408 Gpa.

3. Now switch hyper view to the hyper graph and extract the plots of crosssection forces on the rails.

From this rail section which is near to the hinge pillar has less impact force i.e, 3.4KN.

From this plot we can observe that more impact force is occured at this section this is due to section near to the B pillar and we said that most of stress is generated at the B pillar and it is distributed to the this rail and the impact force is 9.5KN.

3. Nopw extract the plots of intrusion at the hinge pillar, B pillar, and near fuel tank.

From all three intrusion plots we can observe that most displacement is occured at the hinge pillar and reduced displacement at the B pillar and fuel tank. This is because B pillar and fuel tank is crashing into the pole but hinge pillar is not crashing into the pole it is displacing from the pole when crash occurs.

Maximum displacement of the node near hinge pillar is 900mm approximately.

4. Now extract the results of peak velocity and the energy plot.

From the peak velocity plot we can clearly see that velocity of the node is 15.6464 which is the velocity of our model and after crash it is rapidly reduced to the 3 mm/ms which also creates more acceleration and it is problem for the passenger.

From the plot we can see that energy is perfectly balanced and hourglass energy is reduced to zero thid means our simulation is good.

Conclusion : 

Thus side pole crash test is performed on the neon car model using the Hypermesh and radioss solver and extracted the results for crosssection at the rails and intrusions at the hinge pillar, B pillar, and fuel tank and peak velocity at the front door and conclude that more reinforcements are required at the hinge pillar which further prevents from more displacement and stress.