Influence of crash severity and contact surfaces characteristics on the dynamic behavior of forward facing child occupants

The safety of children as occupants, in the event of vehicle collisions, is a pressing issue demanding more research and investigation to reduce harm and minimize injuries. Statistics show that motor vehicle crashes are the leading cause of death and injury for children, despite improved crashworthiness of vehicles and effective child restraint systems (CRS). Studies indicate that during a collision, children develop injury patterns, which are not fully understood. These child injury patterns are different from those experienced by adults due to differences in weight, height, and body proportions. Infants and young children have a disproportionately large head, with a high center of gravity and a weaker neck structure resulting in relatively poor head support. Vehicle speed, weight, impact mode (full-frontal, front offset, angled, side, or rear), type and location of the child restraint system and the interior design of the occupant compartment are some of the important factors that influence injury patterns and degree of harm in a child occupant. In this paper, a multi-body dynamic simulation model is developed, using MADYMO software, to investigate the behavior of a TNO-P3/4 9-month-old forward facing child dummy in a four-point convertible child safety seat. The reasonable correlation between the developed model simulations and experimental results from a CRABI 12-month child dummy sled test indicates that the model is robust. Simulations using three crash pulses, soft, moderate, and severe, are conducted to investigate the influence of crash severity on the child dummy head and thorax accelerations, upper neck forces, and injury parameters. The influence of contact surfaces characteristics is also investigated to shed some light on ways to improve child occupant kinematics during vehicle collisions. The study indicates that dynamic simulation is efficient, cost effective, and viable tool for vehicle occupant protection studies, policy change recommendations, and vehicle design modifications.