Abstract: The second seat row has a high riding rate but a low rider protection level in vehicles running in
China. This paper investigates test methods based on the 100% frontal impact test rule of 2009 version of China
New Car Assessment Program (C-NCAP), and presents a quantitative evaluation method for the biomechanics
limit value of the second row passengers. Tests in vehicle 100% frontal impacts for 29 types of vehicles recently
coming into China’s market showed that the second row occupants suffered fatal neck injury in 17 types of the
vehicles (58.6% of total vehicle samples) and fatal chest injury in 10 types of vehicles (34.5% of total vehicle
samples). The analyses show that the seat belt shoulder strap, neck tension force, and chest compression
displacement have an approximately linear relationship in the dynamics response characteristics of mixed III
type, the 5th percentile, female dummies in the second row seats. The results indicate that the occupant upper
body injury is mainly caused by the safety belt shoulder strap. Therefore, parameter optimization and adjustment
are necessary for common safety belts to effectively reduce the harm.

Key words: vehicle safety, 100% frontal crash test, the second row female dummy, evaluation method, dynamics response