Assignment 6-Frontal Crash Simulation Challenge

Frontal crash-BIW

• Check unit system and either follow[Mg mm s] or [Kg mm ms].
• Create appropriate interface ,friction 0.2 and recommended 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 model 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.

Output requests:

• Sectional force in the rails at location of indicated node 174247.
• Axial force received on the rails from 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.

Procedure

Definig Rigid wall

• A rigid wall was created by selecting the center node on the bumber and then translating it to further distance ahead. Here support>slide 2, Dsearch of 1000and a coloumb friction of 0.1 was used.

Defining contact

• A single contact interface was created using type 7 and deleting all the pre defined contact in the interface. While defining the contact recomended parameters were used.

Defining velocity

• A initial velocity card can be created from the solver deck by right clicking>create>boundary condition>INIVEL. A velocity of 15.64m/s was then given along x direction.

Defining Accelerometer

• Accelorometer were defined to record the acceleration of the vehicle during the crash. After creating that, it should be called on the output block.

Defining Intrusion

• Intrusion was defined by creating a skew>move and then calling it in the output block. Here the given node id and the skew was selected.

All the output parameters such as rigid wall forces, axial forces, sectional forces were called in the output block.

Results

The simulation for the fromtal crash with a rigid wall was performed with normal termination and got all the outputs requested.

The total error (Kinetic, mass, energy) got from the simulation was found to be -1.5% that is well within the acceptable range.

Von-Mises stress

The maximum von mises stress were found to be 1.24E+03.

Energy plot

From the plot its observed when the crash happens tha car deaccelerate and the kinetic energy decreases. The kinetic energy is convered to internal energy and we can see an increase in the plot. The total energy almost remains constant, still deviation can be seen due to the energy error occured during the simulation. The hourgalss energy was well kept with in the range of 5% of total energy.

Rigid wall force

A maximum of 118.945KN force can be observe on the rigid wall at 15ms just after the collision with the bumber. After that the spike gets reduced.

Axial force received on the rails from bumper

The maximum value for the axial force recieved on the rails from the bumber is found to be 30.0975KN.

The recorded value for the acceleration measured by the accelerometers placed on the b pillar are shown in the plot. The acceleration is high for b piller which lie on the left side compared to the right one.

Intrusions on the dash wall

The distance between the node 66695 and the skew is 757.8 and the resultant displacement is 850.8mm therefore the intrusion will be 850.8-757.8=93mm.

Similarly the intrusion for 66244 is 116.5mm.

Sectional force in the rails

The maximum sectional force were found to be 11.9KN.

A pillar cross section

The maximum cross sestion force was found to be 0.771KN.

Shotgun cross sectional forces

The maximum cross sestion force was found to be 2.51KN.

Conclusion

The simualtion for the frontal crash was performed with normal termination and got all the outputs requested.

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File :https://drive.google.com/drive/folders/1sE8WtEO4KqU2GTkzV-XQ2bHd7H5jKEVx?usp=sharing