Evaluation of driver lower extremity injuries in 16 oblique crashes with THOR

Abstract

Injuries to the lower extremity (LE) continue to occur in frontal crashes despite increased attention on the vehicle structure and restraint design. This study focuses on thigh, leg, foot, and ankle injuries as well as occupant factors and intrusion levels. Sixteen vehicles, including three same types, with same moving deformable barriers of the same mass, velocity, and barrier face properties, and the same occupant Test Device for Human Occupant Restraint (THOR) 50th percentile adult male in the driver's seat were used to conduct oblique impact test. Data from the left (driver side) oblique crash tests conducted by National Highway Traffic Safety Administration (NHTSA) were used in this paper to analyse the detailed intrusion characteristics and the driver side THOR injuries from head to foot in these 16 tests. Different regions of the THOR dummy were analysed. Maximum values of all lower extremity injury criteria were obtained and analysed. Intrusion and lower extremity injuries correlation was found, knee airbag and lower extremity injury correlation was also analysed. The foot-well X and Y intrusions in the 16 tests rank from minimum 14 to maximum 309 mm and from −7 to 184 mm, independently. Sixty-nine per cent right knee displacement is greater than the left knee displacement. Thirty-one per cent knee displacement and 44% left upper tibia force of the 16 tests have values that exceed injury assessment reference values. Left upper tibia force was generally greater than other tibia forces. Half of the left upper tibia index (TI) and 37.5% of the right lower TI do not meet the standard value. The foot/ankle complex is generally at a higher risk than the other parts of the leg. Same vehicle reproducibility and injury were also analysed. Right knee displacement, left femur force, left upper tibia force, left upper TI, and left ankle rotation are the most critical injuries in the respective regions of the lower extremity. Intrusion may be more prominent in some frontal damage types than in others, but not the only reason for lower extremity injuries. Other factors that influence LE injuries are the position of driver foot, the geometry of the foot-well area, the direction of intrusion, the impact energy, and acceleration of the floor. Lower extremity is the most frequently injured body region with respect to more serious injuries in the analysed test data.