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Out of range HIC results

dummy-error · 2020-09-08T19:12:43Z

Hi everyone, hope you are all doing ok I couldn’t find any related topic, sorry it that’s already answered. Sorry if it's a bit confusing. I’m trying to demonstrate the difference of the impact of the head against a deformable plate and against a rigid one. This study has been done before with a rigid dummy, but now I’m using the deformable one (all LSTC standard 50th p. male) and a few extra “complications” to bring the problem closer to reality – most of them geometry related, nothing fancy. Turns out that in all cases, the impact is way worse than the previous studies (HIC is like 2x higher) and the difference is even higher when the head impacts the rigid plate. HIC in this case reached 15.000 over and over, when I was expecting a value around 1500. For comparison, the rigid dummy in the new analysis reached 2100, which is acceptable. I double checked everything with the previous analysis, and everything seems fine. I already tried to slightly move the dummy around, also I have tried different types of contacts, but none of them seemed to make any difference whatsoever. There are no errors in the dummy. Do any of you guys have any idea on why is this happening? Or what I shall try next to solve it? If you want more information about my analysis in order to help me, please, feel free to ask. I’m not sure what information you may need. Thanks!

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Negative Volume

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September 24, 2020 6:42 pm

(@negativevolume)

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@dummy-error what are your units for acceleration?

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dummy-error

(@dummy-error)

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September 25, 2020 1:55 am

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Negative Volume

@negativevolume, it's G*e-3. I'm using kg-mm-ms-kN units. The HIC graph is adjusted by that factor we have to enter in the ASII window.

Negative Volume

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(@negativevolume)

Joined: 8 years ago

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Posts: 684

September 25, 2020 12:47 pm

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dummy-error

@dummy-error if you are going to calculate HIC, you need to make sure head acceleration is in G's. You are seeing huge HIC values because you are calculating HIC from G*e-3.

Also, since you are dealing with head impacts, generally HIC 15ms is used as an injury criteria, not HIC 36ms.

Try both of these changes and lets see how it looks.

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