The "No Damage Intercept" of CRASH

Questions/Topics Related to the CRASH computer program
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MSI
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The "No Damage Intercept" of CRASH

Post by MSI »

As part of a response to a question on Truck Crush properties and an error in the referenced SAE paper, we added this topic with important information on the "no damage intercept' and CRASH in general

One thing to note/always check on Crush Coefficients:
  • What is the 'no damage intercept'? Calculate the CRASH inputs A/2B to get the value
    • A lot of folks who sell coefficients force a 4-5 mph intercept
    • Some published crush coefficients are a mess:
      • For example the CRASH3 update by Monk/Guenther
        • They did not understand the science behind CRASH
        • They won the contract for the CRASH3 update on a competitive bid against Calspan.
        • They spent the majority of the contract dollars apparently trying to understand what Ray McHenry/Calspan had created with CRASH/CRASH2
        • They then tried to 'cover their tracks' by arbitrary and subjective 'adjustments' of their crazy values for the crush coefficients A & B and corresponding > 5mph 'no damage intercept' to try to better match Ray's/Calspan's CRASH work better
          • And i say crazy since they had data points from their 'CRASH3' crash test information, the Ray/Calspan/CRASH2 fits had data points, and they should have taken the DATA into consideration for the virtual crush coefficient slope line while also recognizing the need to have a lower, more reasonable 'no damage' intercept. Then they could have found a more scientific basis instead of their arbitrary and subjective adjustments.
      • exercise extreme caution when applying CRASH to very low speed collisions
    Be sure to check! For additional information on CRASH please see the original CRASH references listed here:
    CRASH references in CRASH3 doc.png
    CRASH references in CRASH3 doc.png (298.94 KiB) Viewed 433 times
    Many of the listed papers are available online:
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MSI
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Re: The "No Damage Intercept" of CRASH

Post by MSI »

NEW!! LEASE pricing of msmac3D Software!!
FOR MORE TOPICS see:Forum Index & McHenrySoftware.com
Question? Comment? Please email us (all communications considered confidential)
(c)McHenry Software, Inc ALL Rights Reserved.
MSI
Site Admin
Posts: 1698
Joined: Thu Jun 18, 2009 12:37 pm

Re: The "No Damage Intercept" of CRASH

Post by MSI »

Realized we hadn't posted up HOW to calculate the "no damage intercept of crash"
from post on Truck Crush Properties
Here's a quick summary
  • be sure to make this calculation for whatever crush coefficients you use!
  • For most you will get 4-5 mph "no damage intercept"
  • First verify what the 'no damage intercept is' as far as DeltaV and then ALSO deflection.
  • "no damage intercept" represents the amount of damage in showroom cars if evaluated with damage analysis
  • Keep that in mind...particularly in low speed impacts...when using damage analysis!
we are in the process of a writeup on the process

stay tuned!
Here's data from the Truck coefficients page
Truck A,B No Damage INtercepts.jpg
Truck A,B No Damage INtercepts.jpg (80.75 KiB) Viewed 111 times
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Question? Comment? Please email us (all communications considered confidential)
(c)McHenry Software, Inc ALL Rights Reserved.
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