Abstract: The dummy thorax compression displacement is an indicator of the China New Car Assessment
Program (C-NCAP) to evaluate vehicle passive safety performances. Thorax pendulum calibration tests were
carried out with a Hybrid Ⅲ 50th dummy atan impact velocity of 3.0 m·s-1 to research the effects of ectopic seat
belt on the dummy thorax displacements. Four impact points were selected every 20 mm upward from the 0-cm
point of the normal impact position alongZ axis. Two contrast tests were conducted at a normal seatbelt position
and an ectopic seatbelt position to analyze the two chest displacement curves. The results show that the chest
displacements decrease basically in linear, when the deviation of impact position is less than 60 mm upward
from the 0-cm point of normal chest impact. So, the correct wearing position for seatbelt is at the seatbelt upper
edge being not exceed the adjustment hole in dummy jacket. Thus, the authors suggest that requirement about
the wearing range for seatbelt should be added into future new version of the C-CNAP to evaluate more closely
the true state for the dummy thorax compression criterion.

Key words: vehicle passive safety, crash test, pendulum impact, seatbelt wearing position, thorax displacement, Hybrid Ⅲ 50th dummy