Frontal car crash analysis

Objective: To perform crash analysis on Chrysler Neon frontal model.

Procedure:

• The unit system used for this analysis was [Kg mm ms]
• A planar rigid wall was created in front of the car along the x-axis with a friction value of 0.1.
• A self contact interface was created by setting the entire model as both master and slave. The properties used are as follows:
  • Istif=4
  • Igap=3
  • Stmin=1
  • Gap_min=0.5
  • Inacti=6
  • Fric=0.2
  • Iform=2
  • Idel=2
  • Fscale_gap=0.8
• A separate interface was created with the bumper as master and rails as slave to get the axial force values. The properties used for the interface are the same as mentioned above.
• Mass was added to the system such that the total mass was 700kg and the COG position matches with the fullscale model.
• An initial velocity of 15.64 m/s in x-direction was given to the entire model.
• Cross-sections were created on shotgun and A-pillar regions for checking sectional forces.
• Accelerometers were added on the B-pillar rocker for checking acceleration values.
• Intrusion values were obtained by specifying the nodes in Hyperview.

RESULTS:

• Due to the initial velocity given to the model high kinetic energy can be observed at the beginning. As the crash progresses, the impact due to crash is stored in the BIW in the form of internal energy. Thus, a steady decline in kinetic energy and a gradual increase in internal energy can be seen in the above graph. A gradual increase in contact energy can also be seen when the crash progresses as more elements come into contact with each other.
• The section force value at node 174247 sharply increases and reaches a maximum value of 22.5kN at 15ms. The force value then gradually reduces to 6.5kN at 30ms and then rises to a value of 18kN at 55ms.
• The maximum axial force of 2.75kN was observed at the beginning of the crash at 6ms. After that, a sharp decrease was observed in the axial force value of rail.
  
  
• From the above plots, higher force values were observed for the right shotgun region compared to the left region. The highest value for the right section was 12kN which was observed at 35ms. The peak for the left section was observed at 65ms and the value was 9kN.
  
• The graph for A-pillar sectional forces showed a similar curve till 22ms. After that, an increase in the force was observed for the right pillar and a decrease in the curve was observed for the left pillar. Thus, similar to the above case higher force values were observed for the right section. The peak value for the right pillar was observed at 60ms and the value was 7.5kN. The highest value for the left pillar was observed at 15ms and the value was 5.4kN.
  
  
• At the beginning of the crash, high deceleration values can be observed and this value reduces over time. The highest deceleration value for the left accelerometer was observed to be 33mm/ms^2 and for the right accelerometer, it was observed to be 24mm/ms^2.
  
  
  
• The intrusion plot for the dash wall is shown in the above graph. The intrusion value for node 66244 was found to be 171mm and the intrusion value for node 66695 was found to be 181mm.

Conclusion:

The frontal crash simulation of the Neon Chrysler model was successfully performed by giving the appropriate input conditions. The results obtained in the simulation are summarised below:

• Max section force at node 174247...................... = 22.5kN
• Max axial force on rails due to bumper................ = 2.75kN
• Max section force on right shotgun region........... = 12kN
• Max section force on left shotgun region............. = 9kN
• Max section force on right A-pillar region............. = 7.5kN
• Max section force on left A-pillar region............... = 5.4kN
• Max acceleration value...................................... = 33mm/ms^2
• Max intrusion at dash wall................................. = 181mm

https://drive.google.com/open?id=1BIIWi91kiZjdl5KwontoewI_JtzmREd9