Review of the EURO NCAP Upper Leg Test
Conference contribution, 2011
The EEVC WG17 upper leg test as used in Euro
NCAP was reviewed. Previous work revealed
shortcomings of the EEVC WG17 test set-up.
Recent published accident data show that injuries
to the lower extremities by the bonnet leading edge,
not including ground impacts, only accounted for
5% of all AIS2+ injuries and 4% of all AIS3+
injuries. Previous work and this data indicate a
discrepancy in importance of the upper leg test
between Euro NCAP and real-life injury
Suggested legform impactor threshold values have
so far not been based on human injury risk
transferred to impactor values. The implications of
the proposed improvements to the test set-up from
Snedeker et al. (2005) for Euro NCAP test results
have not been assessed. Both the above issues are
aimed at in this study. They are important as only
with the right targets and evaluation methods,
traffic related injuries can be minimized.
Human injury threshold values for femur and pelvis
impact were derived from applicable and original
PMHS data. Data was scaled to a mid-sized male,
survival analysis with Weibull fit was performed
with exact femur 3-point bending data, logistic
regression with doubly censored pelvis impact data.
Legform thresholds were derived using a linear
regression between impactor and THUMS values
derived form tests conducted by Snedeker et al.
(2005). It is assumed that THUMS and upper leg
surrogates have a similar response. The
implications of the new set-up and thresholds for
Euro NCAP test results were assessed for results
published 2009 and 2010 using empirical
relationships between impact energy, measured
force and moment.
Using this approach, the resulting thresholds to be
used with the legform were determined to be 7.9-
9.0 kN for the pelvis test and 300-365 Nm for the
femur test. These values correspond to 5 and 20%
fracture risk, respectively.
With the currently used set-up and limits, the
average score for the upper leg test is 22% of the
maximum score. With the proposed method and
limits, the average score calculated is 70%. With
only 30% missing, the score matches better with
the accident frequency of bonnet leading edge
induced injuries to lower extremities.