Head Impact Simulation

PEDESTRIAN HEAD IMPACT

USING SIMPLE HEAD

OBJECTIVE: To perform the Head Impact Simulation and calculate the HIC value in the LS-PrePost using a rigid wall.

PROCEDURE(case set up and execution)

The file is loded into Ls-Prepost.

• *Section cards are created for the given FE with ELFORM 16 and have given 3mm as the thckness.

• *Materials cards has been created.I have asisigned *MAT_PIECEWISE_LINEAR_PLASTICITY (MAT024) for the part.

Material properties: Ro:7.85e-3, Pr:0.3, E:210e3

• Section and material is assigned to the part in Parts sections.

• RigidWall Planar has been created ensuring there is at least 7mm gap between the part and rigidwall and the normals are checked.

• Control termination has been defined with termination time as 10ms.

• Database binary D3Plot is also defined with dt as 1ms.

• Database history nodes are created for some nodes to find out the HIC values.

• Database ASCII is defined by opting in the necessasry parameters with Dt as 1ms.

• Automatic single surface contact is defined by defined the part as the slave.

• An initial velocity of 11.11 mm/ms is applied to the part in positive y direction.

• The model is checked with "model checking" tab and the the file has been saved as Keyword file (.k) and is ran in the dyna program manager.

RESULTS OBTAINED:

Head Impact Coefficient

Since this is just an example, the HIC=1.614e8 is so high and this HIC value means the design is not safe and probability of high level head injuries.

USING PEDESTRIAN HEAD

OBJECTIVE: To perform the Head Impact Simulation using *include_transform, define_transformation and to calculate the HIC value in the LS-PrePost using a rigid wall.

Here a main file deck is being created with the following,

• Rigidwall Planar
• Control_Termination with Dt as 20ms
• Database Binary D3Plot with Dt as 1ms
• Nodeout is opt-in in Database ASCII pararameters
• an Initial velocity of 8.33mm/ms (30km/hr) is created by creating a nodeset and assigning to it.

Since the velocity is applied in 70 degree inclined, the velocity vector is broke into two components using the Right triangle rule.

Vx=8.33 sin 70= 7.83 mm/ms

Vz=8.33 cos 70= 2.85 mm/ms

• After this, the Headform deck is called into the main file using *include_transform and the file path and Trand id is mentioned.

• Define_Transformation is defined with ROTATE option and the entities for the movement path is defined and the angle of imapact is gievn as 70 degree.

• The model is checked in model cheker and it's been saved and ran in the manager and normal termination has been occured.

RESULTS OBTAINED:

Head Impact Coefficient

For finding the HIC, the head accelerometer node is being choosed from Nodeout.

Here the HIC value obtained is 664 which means there is a 90% chance of level 1, 55% chance of level 2, 20%chance of level 3 and 5% chance of level 4 occurings as mentioned in Abbreviated Injury Scale (AIS).

USING HOOD

Here, all the method are same as mentioned above. The changes made are mentioned below.

• Hood is used instead of rigid wall
• Section shell with 3mm thickness and MAT20 Rigid material is assigned to the hood.
• Automatic_Surface_To_Surface_Contact is used here by mentioning hood as the master and the headform as the slave. sicnce the negative volume error was occuring for the 3d elements, SOFT=2 is also mentioned to rectify this issue.

RESULTS OBTAINED:

Head Impact Coefficient

Here the HIC value obtained is 1980 which means there is high possibilty of severe injuries which can even cause death.

CONCLUSION

The Head Impact Simulation was ran using *include_transform, define_transformation and the HIC value is calculated using LS-PrePost using a rigid wall and hood.

The HIC value obtained is 664 which means less injuries. As the HIC increases, there is a possibilty of higher injuries.

*all the necessary files are attached with this report.

Thanks,

Rakesh