## Neon Side Crash Analysis on BIW model using Hypermesh RADIOSS

OBJECTIVE

In this challenge, we check and create the properties for a Neon side crash-BIW model and run the simulation & observe results.

Question:

Neon side crash -BIW

• Check the unit system and either follow [Mg mm s] or [Kg mm ms].
• Create an appropriate interface contact, friction 0.2 and recommended parameters.
• Make sure of no penetration and intersections.
• Create a rigid wall with friction 0.1 as per the reference model.
• Compare the model weight with the reference model and use added masses to reach target weight 700kg while getting CG about the required range.
• Initial velocity, as shown in the picture.
• Use model checker to ensure good quality.
• Timestep :0.5 to 0.1 microseconds.
• Run 80ms.

Output requests:

• Sectional force in the cross member.
• The intrusion at B pillar, hinge pillar and fuel tank region. Provide recommendations on what can help to reduce Fuel tank intrusion.
• Peak velocity of the inner node of the door.

PROCEDURE

1. We keep the unit system is [kg mm ms]. We can go to the starter RAD file and check the unit system is given.

2. Create Type 7 Interface (self contact) in which we give recommended properties. Take all nodes as a slave and all elements as a master.

• Igap=3: To avoid initial penetrations, the solver considers the variable gap with the gap scale correction factor and also the size of the mesh is taken into account.
• Fscalegap = 0.8. Gap scale correction factor. The gap nodes and segments keep on changing because of constant vibration generate while calculating the force.
• Gapmin=0.5
• Friction = 0.2
• Idel= 2 i.e. when one element is deleted, the master segment is removed from the contact and slave nodes became free are also removed.
• Inacti=6,  It adjusts the master segment to remove the initial penetration and it increases stability and gives space to nodes for vibration.
• Istf= 4, By this we calculate Initial contact stiffness Ko= min. (Km, Ks)
km= master segment stiffness
and Ks= equivalent nodal stiffness
• Iform= 2, Friction based on stiffness formulation: sliding forces are computed using stiffness parameters of the interface.
• Stmin=1 kN/mm, Minimum stiffness to avoid too soft contact.

3. For checking Interference and penetration, we can check into Hypermesh and Hypercrash both.

while checking into Hypercrash some errors I got we can fix into Hypercrash itself but there is a problem, we cant export the file and open into Hypermesh because in the student version of Hypercrash node limit is 10,000 for exporting. so, it shows this command "please reduce the no. of nodes below 10,000"

So, we check the error in Hypercrash and fix it into Hypermesh.
we can see errors in Hypermesh also can fix it into Hypermesh itself and sometimes we did this too.
But if nodes are under the limit then it is preferable that we fix errors in the Hypercrash itself because in Hypermesh we can see the Node id and can directly reach that node by search option.

4. Create an infinite cylindrical rigid wall normal to the Z-axis at coordinates (2250, 1020, 2000) and select Group node of name 1123 INTER_GROUP_1123.

The diameter is 254 mm and friction is 0.1

5. Masses are added to reach target weight 700kg while getting CG about the required range (Near to the seat Reinforcement).

6. Initial velocity 35 mph which is equal to 15.64 m/s or mm/ms.

7. Timestep 0.5 microseconds and Run for 80ms and frequency of animation file are 5. so, by this we get 16 animation files.

After doing all this work, again we run model checker & ensure good quality by checking errors and warning.

After that, we run the simulation.

RESULTS

1. For getting the sectional force on the Front reinforcement and back reinforcement, create TH card for getting graphs.

• For the front reinforcement (seat reinforcement) the value keeps on fluctuating but the max. value is nearly equal to 12 KN at the end of the simulation.
• For the back reinforcement the value keeps on fluctuating but it increases to its max. value is nearly equal to 17 KN between 20-25 ms.

2. The intrusion at Hinge pillar, B-pillar and fuel tank region.

For that, we create a TH card with selecting the node on the particular location.

Resultant displacement graphs for Hinge pillar, B-pillar and fuel tank region respectively.

The intrusion values of all three parts are as follows.

• For Hinge pillar nearly equal to 710 mm
• For B-pillar nearly equal to 300 mm
• For fuel tank nearly equal to 275 mm

To reduce Fuel tank intrusion we can use another material having high stiffness and high capacity of shock-absorbing and simultaneously also we can use some extra reinforcement having more mass.

3. Peak velocity at the inner node of node id 337772 of the Door

• Peak velocity is observed at the beginning of the simulation is equal to 16 mm/ms or 16 m/s.
• Velocity keeps on decreases up to 11 ms after that it fluctuates and decreases to 4 mm/ms.

4. Energy curves plots

• We all know that kinetic energy is converted into internal energy while crash, as element gets deforms it absorbs energy.
• The decrement we observe in total energy is due to some energy gets converted into contact energy.

• The contact energy is increased to avoiding penetration between the elements by increasing the stiffness.
• Contact energy keeps on increasing. As the simulation stops at 80 ms if it keeps on running we get more value of contact energy.

Hourglass energy is less, not high as other plots.

5. Energy error and mass error

The energy error starts from -0.1% and ends with -2.5%. We can check in the Engine OUT file. It is within considerable limits.
Energy error is negative so it means -2.5% energy dissipates during the simulation.

Maass error is 0.73 %.

CONCLUSION

Successfully performed the Neon Side Crash simulation and the following observations are analyzed.

• Increase mass according to the main model and change center of gravity keep it on a proper position near to the seat Reinforcement.
• Create a cylindrical Rigid wall at the required position for proper side crash simulation results.
• Create a TYPE-7 interface contact with the recommended parameters.
• To reduce Fuel tank intrusion we can use another material having high stiffness and high capacity of shock-absorbing and simultaneously also we can use some extra reinforcement having more mass.
• For the seat reinforcement & back reinforcement, max. value is nearly equal to 12 KN & 17 KN respectively.
• The intrusion at the Hinge pillar, B-pillar and fuel tank region is 710mm, 300mm, 275mm respectively.
• Peak velocity at the inner node of the Door is 16 mm/ms.

Neon Side Crash Analysis on BIW model using Hypermesh RADIOSS

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