Occupant analysis and seat design to reduce neck injury from rear end impact

Occupant injury from rear end impact is rapidly becoming one of the most aggravating traffic safety problems with high human suffering and societal costs. Although rear end impact occurs at a relatively low speed, it may cause permanent disability due to neck injuries resulting from an abrupt moment, shear force, and tension/compression force at the occipital condyles. The analysis is performed for a combined occupant-seat model response, using the SAFE (Safety Analysis For occupant crash Environment) computer program. A simulation model is established to match the sled tests. A parameter study is conducted for various physical and mechanical properties. Seat design has been carried out based on the design of experiment (DOE) process with respect to five parameters: seat back collapse angle, joint stiffness between the seat back and seat cushion, headrest stiffness, the clearance between the occupant's head and headrest, and friction coefficient of the seat back. An orthogonal array is employed for the DOE. A good design has been found from the results of the experiment. It is found that reductions of the seat back collapse angle and joint stiffness are the most effective for preventing neck injuries.