Influence of vehicle secondary impact following an emergency braking on an unbelted occupant's neck, head and thorax injuries

Passive safety has for many years reduced the number of fatalities on the roads. However, its effect on occupants safety has now stabilised, meaning that new active safety features are needed to reduce further the number of casualties. These active safety features, like autonomous emergency braking (AEB), aim to prevent vehicle collisions and reduce the vehicle kinetic energy on impact. A previous study has shown that unbelted occupants kinematics are affected by the pre-braking phase, suggesting that the occupant's hand positions on the steering wheel, combined with a bracing behaviour, could cause the occupant to miss the deploying airbag in the case of a secondary rigid wall impact. This paper will investigate the variations of the secondary vehicle impact crash patterns by calculating crash pulses based on typical vehicle frontal accident scenarios and conclude on these effects on the human occupant's neck, head and thorax injuries.