Assignment 7-Side Pole Crash Simulation Challenge

Question:

Neon side 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 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 the target weight of 700kg while getting CG about the required range.
• Initial velocity is shown in the picture.
• Use a 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 an inner node of the door.

Procedure:

1. Check the unit system of the given starter file (neon_side_reduced_0000.rad) by opening it in Notepad/Notepad ++.

Open Hypercrash, (from applications tab of Hypermesh) and set the unit system: kN mm ms kg.

Now drag and drop the starter file (neon_side_reduced_0000.rad) in the Hypercrash.

2. To check penetrations and Intersections, Quality -> Check All Solver Contact Interfaces -> Select all parts -> Check penetration.

There are no penetrations or intersections in the model.

3. 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.

We have to add mass to the current model which will be equal to 700 kg and CG in the required range.

To Check the mass and CG of the current model,

Mass -> Balancing

The pink mark shows the current CG of the model (click specs like icon)

The total mass to be added to get 700 kg is 533.7 kg

To Add required mass, Load case -> Added Mass

Create New -> Type 1 (Mass distributed to each node of node group) -> Added mass and select the required components where the mass is to be added.

We have added 4 new masses of a total of 533.7 kg to the current model.

Now we have gained the CG in the required range and mass of 700 kg

4. Create an appropriate interface, friction 0.2, and recommended parameters.

Delete all the groups to create the contact interface (Groups in model browser) for the current model.

Create a new interface named as Self-Impact with recommended properties.

In Model Browser,

Create -> Contact

Type 7

Istf = 4, Igap = 2, Idel = 2, Stmin = 1, Gapmin >= 0.5, Inacti = 6, Iform = 2.

For Self-Impact – select all components for Master & Slave selection

After creating the contact interface, review to check whether the Master and Salves are selected properly.

5. Create a rigid wall with the friction of 0.1

In Solver browser, Create -> RWALL -> CYL

For creating a rigid wall, we need a reference node – for that temp node is selected on the model, and using translate duplicating the temp node we can get the reference node.

Now select that reference node for XM, YM, ZM as values for the rigid wall

For grnod_ID1 – Create a set for selecting all the nodes of the model

Normal = 0,0,1 as the normal of the rigid plane is to be in the z-axis for the model.

Slide = 2, Dsearch = 1500, Diameter= 254 & Fric = 0.1 (given).

6. Initial velocity 35 mph.

Create -> Boundary Conditions -> INIVEL

Give Velocity component: 15.6464 kmph and select all the sets in the grnd_ID.

Using Review check whether all the sets are assigned with the given Initial Velocity.

For Output Requests

7. Sectional Forces in the cross member.

We have to create Sectional Forces on the Cross members

Before creating Sectional Forces, we have to create moving frames on the components.

Create -> Frame -> MOV -> create by node reference -> z axis -> yz plane,

This system will be selected in the frame_ID while creating sections.

Create -> SECT -> SECT

Select the frame nodes on the component for the N1, N2, N3 then deltaT = 0.1, alpha = 0.628 & Ifame = 12.

For grshell_id, create a set and select the elements around the frame created of the component.

8. Intrusions on the Fuel-tank, B-pillar, Seat.

Create Springs between the Fuel-tank, B-pillar, Seat components.

Assign spring properties, select card image = P4_spring with mass = 0.001 and stiffness k = 0.001

9. Creating TH for all the output requests.

In Solver browser,

TH – SECT – Self Impact

RWALL – Side Pole

Section – B-Pillar, Seat-rail

Spring – Fuel-tank, B-pillar, Seat

Node – Peak Velocity

10. In ENG_RUN set Tstop = 80 & ENG_ANIM_DT set Tfreq = 5.0

11 .Check for the model error in both Hypermesh & Hypercrash

If there is any error, try to sort it out by auto-resolve

Hypermesh -> Tools -> Model Checker -> Radioss

Hypercrash -> Quality -> Model Checker -> Run

12. In the Analysis panel, select Radioss and save the input file as neon_front_cog_run_0000.rad in a separate folder (to save the animation files), mentioning the option = “-nt 4”.

Then run the input file, by selecting Radioss to perform the simulation.

ELAPSED TIME 2081.39 s

0:34:41

Energy Error = -3.6%

Mass Error = 0.1024E-01

13. Select Results, to view the simulation – Select the Contour for displacement, von mises, and save the files.

14. Go to Hypergraph, 2D to plot the desired graph for comparison.

Energy Curves:

Max Energy

- Internal Energy (79.5,33541.8)

- Kinetic Energy (0.0,85895.15)

- Total Energy (0.0,85895.15)

Contact Energy:

Contact energy increases, from zero at 5ms when the car hits the side pole it started increasing rapidly at 30ms and reaches a maximum of 2799.5

Rigid Wall:

The rigid wall has a max of 108.7 kN at 35 ms, Also the first peak is due to the first contact of the car on the rigid wall which can be confirmed from the contact energy graph.

Output Requests

Sectional Forces:

Max cross-sectional force – Seat Rail 2.15 kN/mm at 68 ms

– B-Pillar 1.8 kN/mm at 34 ms

Self–Impact Interface:

Self-impact forces reach 119.85 kN at 45.5 ms.

Intrusion – Spring Displacement:

9900038 – Seat – 561.96 mm

9900037 – B-Pillar – 905.26 mm

9900039 – Fuel Tank – 777 mm

Peak Velocity:

The peak velocity of node 337773 in the node of the inner door is 16 mm/ms at 5 ms.

Results:

Thus, the given front half model was made to do the side pole simulation with the required given input setup along with the output parameters calculated.

Learning Outcome:

Setting up for car side pole crash

Adding masses to alter CG at the required place

Adding Boundary Conditions

Setting up the interface with recommended properties

Setting up Sectional forces for the calculation

Setting up Intrusion of nodes with springs

Calculating Peak Velocity of the node

Debugging errors

Providing results with output blocks