Week-7 Head Impact

AIM: To perform Head Impact simulation using LS-DYNA on child pedestrain head and calculate the Head Impact Coefficient (HIC).

Unit System: Kg mm ms

CASES :

1. Impact of Simple head on rigidwall.
2. Impact of Pedestrain headform on rigidwall.
3. Impact of Pedestrain headform on hood.

Procedure:

CASE 1: Impact of Simple head( sphere) on rigidwall.

1. After importing the model, first material and and section is assigned to the part.

2. A rigidwall is created using rigidwall-Planar

3. A automatic single surface contact is given to head and initial velocity of 11.11 mm/ms is given. Before assigning velocity a velocity Node set is created and normal vector direction of rigidwall is pointed towards head.

4. From the control card termination time of 10 ms is given. And proper Database card are selected (D3plot, ASCII)

Results:

In below result complete kinetic energy is converted to internal energy and Total energy curve is constant throughout, which shows that model is working fine.

A very high HIC is achieved; HIC = 4.783e+7

Animation:

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CASE 2: Impact of Pedestrain headform on rigidwall

1. Here, first a transformation is defined using Define-transformation. with that TransId is created.

2. That Transid is used in Include-transform to rotate the given headform.

3. Now, all the important inputs like termination time, initial velocity, contacts are assigned as above.

Results:

Strain

A very high HIC is achieved; HIC = 6.396e+4.

Animation :

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CASE 3: Impact of Pedestrain headform on hood

1. First subfile with transformation is created so that we accidently disturb our headform or hood file.

2. Here first meshed hood file is called to main file using include.

3. Similarly, pedestrain headform file is called.

4. Now head direction should be changed as per the real life scenario.

Here velocities in X & Z direction is given. -11.11*cos45° mm/ms.

Now same procedure is followed as secong case. All important parameters like termination time, contacts are assigned.

5. While give surface to surface contact, each part of head is individually contacted with the hood. Where hood is given master id and head parts are given slave.

For termination time of 50ms, simulation took 12min, 52 sec.

Results:

Animation:

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Conclusion:

1. HIC value is maximum in case of rigidwall impact as rigidwall offer more resistance force. All the deformation happen on the head.

2. Due to more resistance by rigidwall, stress and corresponding strain is also more in that case compaired to hood impact case.

2. During hood impact, there is deformation in hood, due to which some part of energy is absorbed by the hood. And impact on the head is less compaired to rigidwall.