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Femur Force

Overview​

Femur Force represents the maximum compressive force exerted on the femur during an impact or collision event [1]. If the ATD used in testing has an established Injury Assessment Reference Value (IARV), the peak femur compression is reported as a percentage of that IARV to indicate potential injury severity [2]. The IARV represents a threshold value used to evaluate the risk of injury during an impact, each ATD has their own IARV value depending on the type, sex, and size of the dummy [2].

Femur Force
Femur Force

Required Signals​

  • Left/Right Femur Force (Z)

Calculation​

  1. Convert femur force to newtons (N) (if applicable)
  2. Filter femur force signal (CFC = 600)
  3. Truncate signal to start at 0 seconds (if applicable)
  4. Find the minimum femur force (the maximum compressive force)
  5. Calculate the percent of the IARV that the minimum femur force reaches

NCAP Combined Injury Rating​

The femur force metric is used in the NCAP frontal impact for the HIII M50 and HII F05 dummies.

Pfemur,HIII−M50(2+)=11+e(5.795−0.5196∗F)(Equation 1)\tag{Equation 1}P_{femur, HIII-M50}(2+) = \frac{1}{1+e^{(5.795-0.5196*F)}} Pfemur,HIII−F05(2+)=11+e(5.7949−0.7619∗F)(Equation 2)\tag{Equation 2}P_{femur, HIII-F05}(2+) = \frac{1}{1+e^{(5.7949-0.7619*F)}}
Femur Force
NCAP Probability of Injury for Femur Force for HIII M50 and HIII F05 [3]

Femur Compression Injury Risk Value [4] [5] [6]​

ATDFemur Compression Injury Risk Value (N)
HIII - F05-6805
HIII - M50-10,008
HIII - M95-12,700
THOR - M50-10,577

References​

[1] AlTurki AA, AlAqeely KS, AlMugren TS, AlZimami IS. Analysis of femoral fracture post motor vehicle accidents. Saudi Med J. 2019 Jan;40(1):41-44.

[2] "Frontal Offset Crashworthiness Evaluation". Guidelines for Rating Injury Measures, Insurance Institute for Highway Safety, June 2009.

[3] National Highway Traffic Safety Administration. Final Rule; Response to Petitions for Reconsideration: Federal Motor Vehicle Safety Standards; Head Restraints. Docket No. NHTSA-2006-26555-0120, U.S. Department of Transportation, 2006.

[4] National Highway Traffic Safety Administration. (2000). Federal Motor Vehicle Safety Standards; Occupant Crash Protection; Final Rule. Federal Register, 65(208), 67691–67703.

[5] Craig, M., et al. "Injury criteria for the THOR 50th male ATD." National Highway Traffic Safety Administration (2020).

[6] Bandak, Faris, et al. "Development of improved injury criteria for the assessment of advanced automotive restraint systems: II." (1999).