What is The "No Damage Intercept" of CRASH
Posted: Mon Jan 13, 2020 1:25 pm
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:
For additional information,
For additional information on damage analysis & CRASH, please see:
One thing to note/always check on Crush Coefficients:
- What is the 'no damage intercept'?
- Calculate the CRASH inputs A/B 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 (who invented CRASH!).
- They spent the majority of the contract dollars apparently trying to understand what Ray McHenry/Calspan had created with CRASH/CRASH2
- Monk/Guenther 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,
- 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.
- And i say crazy since
- 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
- Use exercise extreme caution when applying CRASH, aka Damage Analysis, particularly to very low speed collisions
- For example the CRASH3 update by Monk/Guenther
For additional information,
- See the topic Truck Crush properties for a sample check.
- Please see Over 60 years of McHenry Highway Safety Publications
- Not all the documents are online
- We have all the documents,
- if you want/need one not yet online, let us know and we can see about scanning it an posting online
For additional information on damage analysis & CRASH, please see:
- The Algorithms of CRASH, paper presented at 2001 SECCC, Aug 2001
- NHTSA CRASH3 Technical Manual - 1986 NHTSA collection/summary of CRASH papers
- From the McHenry Forum Topic on CRASH:
- Why was the CRASH program created?
- What Speed Should I Use to Calculate CRASH3 A&B Coeff?
- Is CRASH damage analysis a virtual relationship?
- Should a CRASH type damage analysis include induced damage?
- What is the "No Damage Intercept" of CRASH
- Can You Use Maximum Crush For CRASH A&B Crush Coefficients?
- Effects of Restitution in the Application of Crush Coefficients
- Crush Coefficients Conversions: CRASH (McHenry), Campbell, WinSMASH (Prasad)
..and more, see the McHenry Forum and specifically the McHenry Forum topic CRASH and Damage Analysis