Can you calculate the lateral Delta-V from the acceleration rates?

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MSI
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Can you calculate the lateral Delta-V from the acceleration rates?

Post by MSI »

Q: (Posted to Crash Forum and with no answers after 3 days i decided to respond and also post here)
Hi, is it possible to calculate the lateral Delta-V from the acceleration rates? I have a long delta v. Target vehicle hit on the near side as it was turning right.
lateral deltaV.jpg
lateral deltaV.jpg (57.65 KiB) Viewed 52 times
A: Answer is YES...however...it depends...
  • On the logic/trigger for the recording of lateral acceleration since when it starts and ends may affect the total lateral DeltaV calculated.
For full scale testing and simulation[*] acceleration is used to calculate the DeltaV total and in the X & Y directions
  • See link below for background information, equations, and references
    The reference cited also discusses issues we found with full scale test analysis procedures:
    • Testing facilities need to consider the possibility of a changing sign of the lateral acceleration: it can cause issues.
    • We recommend calculating the total deltaV and PDOF and then determine the lateral acceleration (see paper referenced in link)
    • Of course in a t-bone this shouldn't be an issue (all lateral acceleration is in one direction)
Here is the link: Brian

FOOTNOTE:
[*]Simulations that use acceleration to calculate DeltaV are ONLY those that calculate crush forces and moments DURING the collision and so have acceleration time histories available (like SMAC)
Simulations programs that assume "Instantaneous exchange of momentum" during collisions DO NOT calculate any crush forces as they occur so the time history of accelerations during simulated collisions are not calculated or available.
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MSI
Site Admin
Posts: 1408
Joined: Thu Jun 18, 2009 12:37 pm

Re: Can you calculate the lateral Delta-V from the acceleration rates?

Post by MSI »

After responding to this question I realized that this thread should also include some fundamentals on integration to determine velocity and displacement.
I did a quick search of the internet and here is an example of some related notes: There are also many others are available on the web.
Question? Comment? Please email forum@mchenrysoftware.com. Also see the McHenry Forum Index
Visit McHenrySoftware.com for technical information & software.
(c) McHenry Software, Inc ALL Rights Reserved.

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