NEON FRONTAL CRASH ANALYSIS USING HYPERMESH AND RADIOSS

OBJECTIVE:

To perform a crash test using the given model of the car and to determine the forces acting on different cross-sections of the car during the impact.

Frontal crash-BIW:

• Check unit system and either follow[Mg mm s] or [Kg mm ms].
• Create an appropriate interface, friction 0.2 and recommended parameters.
• Make sure of no penetrations and intersections.
• Correct rigid bodies if any issues.
• Create a rigid wall with friction 0.1.
• Compare the model weight with the full-scale 300k nodes model and use added masses to reach the target weight of 700kg while getting CG about the required range.
• Initial velocity 35 mph.
• Use a model checker to ensure good quality.
• Timestep :0.5 to 0.1 microseconds.
• Run 80ms

Output requests:

• Sectional force in the rails at the location of indicated node 174247.
• The axial force received on the rails from the bumper.
• Shotgun cross-sectional forces.
• A pillar cross-section.
• Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).
• Intrusions on the dash wall 66695,66244.

MODEL OF THE CAR:

GIVEN MODEL FOR FRONTAL CRASH-BIW:

PROCEDURE:

The main stages of this crash impact analysis are :

1. CHECKING THE UNIT SYSTEM:

The unit system is set to [Kg mm ms]

2. CREATING CONTACT INTERFACES:

A type 7 contact interface is created with the recommended properties.

• [Istf] Stiffness definition=4: K=min(Km,Ks)
• [Igap] Gap/element option=2: Variable gap + scale correction
• [Gapmin] Min. gap for impact activ =.5.
• [Inacti] Stiffness deactiv. (init. penetration)=6: Gap is variable with time (init. penetration is computed)
• [Fric] Coulomb friction=0.2.
• [Iform] Friction penalty formulation=2: Stiffness.

3. CENTER OF GRAVITY AND MASS ADDITION:

The given model has a mass of 188kg and the target mass is 700kg.

Masses were added at certain cross sections to reach the target mass and to maintain the position of COG as per the requirements.

4. CREATING ACCELEROMETERS AT DIFFERENT LOCATIONS:

5. CREATING SECTIONS AT DIFFERENT LOCATIONS:

6. CREATING TIME HISTORY FOR INTRUSIONS ON THE DASH WALL:

7. CREATING RIGID WALL:

8. SETTING UP INITIAL VELOCITY:

Velocity = 35mph =15.6464mm/ms

9. SETTING UP TIME HISTORY:

10. CHECK FOR PENETRATIONS AND INTERSECTIONS:

The penetrations and intersections check was done in hypercrash and in hypermesh, all the intersections and penetrations were removed before starting the simulation.

RESULTS:

DISPLACEMENT:

VON MISES:

NODE INTRUSIONS:

TOTAL RESULTANT FORCE IN VARIOUS SECTIONS:

1. SHOTGUN:

2. RAILS:

3. A-PILLER:

4.HINGE PILLER:

5. SURFACE BEHIND THE BUMPER:

INTERNAL AND KINETIC ENERGY:

TOTAL ENERGY:

CONCLUSIONS:

Results from the 10 created sections show that the maximum force is acting upon the rails, followed by the surface behind the bumper and the shotgun sections. The least value of force is absorbed by the A-pillar. There is no deformation in the A-pillar, (which) means that intrusion into the cabin was minimal and the risk for injury was also minimal.

The results are a little inaccurate since the given model is only a biw model of the car which has only the required parts.

The Center of gravity also plays an important role in the crash analysis. It is an important concept in determining the stability of a structure.

The kinetic energy is reducing because it is converted into internal energy and total energy. The energy error, mass error and hourglass energy are under the acceptable values.

Modern cars protect drivers and passengers in frontal, rear and offset crashes by using crumple zones to absorb crash energy. This means that the car absorbs the impact of the crash, not the driver or passengers. The cabin of the car should keep its shape in frontal crashes to protect the driver and passenger's space.

Crumple zones are essentially the front structure of the vehicle, from the bumper to the base of the windshield. If this is weak, you get intrusion into the passenger compartment during a frontal collision. So you want crumple zones to absorb the energy and come to a stop here (the base of the windshield).

The use of high-strength steel isn't about turning passenger cars into invincible tanks but controlling crash energy and minimizing weight. Heavy does not mean safe. These advances in steel—along with strategic use of other materials such as aluminum, magnesium, and carbon fibre—allow engineers to design structures that can dissipate and redirect crash forces. For example, the new Cadillac CTS uses lightweight aluminum "crush cans" upfront to soak up a lot of energy before an impact reaches the passengers. Carmakers use a variety of materials and steel strengths in a car's frame to redistribute crash forces and protect passengers. By using softer metals on the exterior parts and gradually using stronger steel through the crush zone and as part of the passenger cell, the violent energy from the impact can be controlled, keeping the humans inside safe.