SIDE CRASH ANALYSIS OF NEON BIW MODEL

SIDE CRASH ANALYSIS OF A NEON BIW MODEL

OBJECTIVE:

To perform the side crash analysis of neon BIW model on the rigid pole and analyze the b pillar, fuel tank, hinge pillar intrusion and the energy curves are generated for the BIW model during the impact and finally the peak velocity for the inner node of the door is also generated.

The preprocessing is done by the HYPER MESH and the analysis is done by the RADIOSS solver and the results are interpreted using the HYPERVIEW and HYPERGRAPH

MODEL SETUP:

The model is imported using HYPERMESH, then run model analysis to check for errors and warnings. There are some free nodes, free masses and unwanted Springs attached in the model. Those are deleted.

There are no penetrations and intersection in this model.

Some contact interfaces are already defined for individual parts. But I would like to make this model with proper self-contact, so those defined contacts were also deleted.

Now, the meshed model of neon BIW is ready for pre-processing. The unit system followed is kG kN mm ms.

CONTACT INTERFACE:

The TYPE 7 contact interface is used to define \"self-contact\" for the whole model. The nodes are assigned as slaves and the elements are assigned as master. The recommended parameters are

PARAMETER	VALUE
Inacti	6
Idel	2
Gapmin	1
Igap	2
Istf	4
Iform	2
Ifric	0.2

RIGID WALL:

A cylindrical rigid wall is created in side near the B pillar of the door for crash scenario. The parameters like friction 0.1, and Diameter 100mm and Dsearch 1000mm are defined.

ADDED MASS:

The distributed mass 700 kg is added to some components as distributing 0.03834kg per node. The added mass is assigned to move the COG of model to the middle. Because the COG is a main thing to define rolling behavior of model in the event of crash.

INITIAL VELOCITY:

The Initial velocity of the model is 35MPh which is 15.65mm/ms. The initial velocity is given for entire model in positive Y-axis direction.

TIME STEP:

The time step is set to 0.0005 ms and a runtime of 80ms.

CROSS-SECTION:

The cross-section is created on some parts to analyze the forces received on that section. The section is created on rail member and seat member. The normal is set as local Z-Axis to process the flow of forces.

OUTPUT REQUEST:

The TH card is created in such a way that we can request output in HYPERGRAPH. The output requests for sectional force in cross member, intrusions in B pillar, fuel tank, hinge pillar and Peak velocity of the inner node of the door.

DISPLACEMENT CONTOUR:

VON MISES CONTOUR:

ENERGY GRAPH:

The maximum internal energy absorbed by the model is 20940 joules.

The kinetic energy of the body at starting is 85500 joules after the impact it reduces to 62860 joules.

The total energy is nearly constant so there is an energy balance and energy error is -1.5%.

ENERGY TABLE:

SECTIONAL FORCES IN THE RAIL CROSS MEMBER:

The maximum force received on the rail cross member section is 3.5KN at 68ms.

SECTIONAL FORCES IN THE SEAT CROSS MEMBER:

The maximum force received on the rail cross member section is 1.25KN at 77ms.

INTRUSION AT B PILLAR:

By using the hyper view, the distance between the two nodes is found, so by using the distance the intrusion is calculated at the b pillar region, the intrusion at B pillar is 755mm(1325-570).

INTRUSION AT THE HINGE PILLAR:

By using the hyper view, the distance between the two nodes is found, so by using the distance the intrusion is calculated at the hinge pillar, the intrusion at hinge pillar is 213mm(1305-1092).

INTRUSION AT THE FUEL TANK:

By using the hyper view, the distance between the two nodes is found, so by using the distance the intrusion is calculated at the fuel tank region, the intrusion at fuel tank region is 859mm(1325-466).

PEAK VELOCITY AT THE INNER NODE OF THE DOOR:

The initial velocity at the inner door node is 15.64mm/ms after the impact the velocity increased up to 16mm/ms and goes on decreasing due to the decrease in the kinetic energy of the BIW model.

The peak velocity at the door is monitored because the passenger inside the car experience more or less the same velocity.

RECOMMENDATIONS FOR REDUCING THE FUEL TANK REGION INTRUSIONS:

During side impact, the door comes first in contact with the hitting vehicle. As the space available between the occupants sitting inside the vehicle and the inner door trims is limited and there is no space for energy absorption as compared to the front-end collisions.

Therefore, the design of the side impact beam inside the door should be such that it can sustain high load with smaller displacement.

• An anti-intrusion bar or beam is a safety device, installed in most cars and other ground vehicles, which must protect passengers from side impacts.

Side impacts are particularly dangerous for two reasons:

a) The location of impact is very close to the passenger, who can be immediately reached by the impacting vehicle;

b) In many side-impact accidents, the impacting vehicle may be larger, taller, heavier, or structurally stiffer than the struck vehicle.

The role of an anti-intrusion bar is to absorb the kinetic energy of the colliding vehicles that is partially converted into internal work of the members involved in the crash.

Therefore, increasing the side door strength by adding another anti-intrusion bar, we can reduce the amount of intrusion to the fuel tank.

• Also by adding another cross member near the fuel tank, we can reduce the intrusions.

RESULTS:

Intrusion at B pillar=755mm

Intrusion at hinge pillar=213mm

Intrusion at fuel tank region=859mm

Internal energy=20940 joules

Max. Sectional force at rail cross member =3.5kn

Max. Sectional force at seat cross member =1.25kn

Peak velocity at inner node of door=16m/s