A numerical investigation into the effect of CRS misuse on the injury potential of children in frontal and side impact crashes.

This research focuses on an investigation into the head and neck injuries sustained by toddlers due to CRS misuse under frontal and side impact crashes. A fully deformable FE model incorporating a Hybrid III 3-year-old dummy was developed which has been previously validated for frontal impacts under CMVSS 208 and FMVSS 213 testing conditions. Furthermore, this model has also been validated under near-side impact conditions in accordance to crash tests carried out by NHTSA. In addition, numerical models incorporating a Q3/Q3s prototype child crash test dummies were developed. The objective of this research was to study the effect of seatbelt slack and the absence of the top tether strap on the head and neck injuries sustained by toddlers in a vehicle crash. Numerical simulations were conducted under full frontal and near side impact crash testing conditions in accordance with FMVSS 213 for the Hybrid III 3-year-old dummy and Q3/Q3s dummies in the absence and presence of slack in the seatbelt webbing, and in the absence and presence of the top tether strap. In addition, the effect of using a cross-shaped rigid ISOFIX system was also investigated. An analysis of the head and chest accelerations, neck loads and moments was completed to investigate the potential of injury due to CRS misuse. An increase in HIC(15) by approximately 30-40% for the frontal impact and 10-20% for the near-side impact respectively was observed for the Q3 child dummy due to both forms of CRS misuse. In the absence of the top tether strap the forward head excursions were observed to be increased by approximately 70% for the Hybrid III 3-year-old dummy and 40% for the Q3 dummy, respectively. Use of the cross-shaped rigid ISOFIX system illustrated a reduction in head and neck injury parameters, for both frontal and side impact conditions, in the absence and presence of CRS misuse. CRS misuse results in a significant increase in injury parameters and potential for contact related head injuries. Use of a rigid ISOFIX system to restrain a CRS provides better CRS and dummy confinement and reduced injury potential than a flexible ISOFIX system.