A nonlinear occupant-restraint system model for predicting human injuries caused by vertical impact

High-amplitude biodynamic responses may occur when the human body is subjected to a vertical impact load induced by explosions or crashes. In order to improve the occupant protection capability of a vehicle, numerical calculation should be accomplished to obtain body responses via an accurate anthropomorphic model during the design stage. In this study, a nonlinear two-dimensional multi-body 'occupant-restraint system' model was developed to predict the dynamic response characteristics of a seated human under a vertical load. A four-point harness was introduced to simulate the restraint effect on the human body. Parameters of the multi-body model were optimized based on the Error Assessment of Response Time Histories (EARTH) metric and data from drop tower tests. Errors between experimental and numerical results about the peak value and the duration of main peak were 9.2% and 12.7%, respectively. To improve the practicality of the constructed model, a buffer device, which could control the load transmitted to the torso, was then implanted in the seat to study the regular pattern among the lumbar force, cushion force, and cushion stroke. With low computation cost, the model showed the ability of assessing and reducing occupant injuries and guiding the matching process between the cushion element and seat system.