The Effect of using Rigid ISOFIX on the Injury Potential of Toddlers in Near-side Impact Crashes

This research focuses on the injury potential of children seated in forward facing child safety seats during side impact crashes in a near side seated position. Side impact dynamic sled tests were conducted by NHTSA at Transportation Research Center Inc. using a Hybrid III 3-year-old child dummy in convertible forward/rearward child safety seat. The seat was equipped with a LATCH and a top tether and the dummy was positioned in forward-facing/near-side configuration. The test was completed using an acceleration pulse with a closing speed of 24.1 km/hr, in the presence of a rigid wall and absence of a vehicle body. A fully deformable finite element model of a child restraint seat, for side impact crash investigations, has been developed which has also been previously validated for frontal and far side impacts. A numerical model utilizing a Hybrid III 3-year-old dummy, employing a similar set-up as the experimental sled test was generated and simulated using LS-DYNA®. The numerical model was validated by comparing the head and the chest accelerations, resultant upper and lower neck forces and moments from the experimental and numerical tests. The simulation results were observed to be in good agreement to the experimental observations. Further numerical simulations were completed employing a rigid ISOFIX system with two different cross-sectional geometries for the anchoring mechanism. It was observed from the simulation results that the use of both rigid ISOFIX geometries was effective in reducing resultant chest accelerations by approximately 40 percent. A reduction of approximately 20 to 30 percent was observed in lateral shear and lateral bending of the dummy’s neck. Of the two rigid ISOFIX geometries considered, the cross-shaped system effectively reduced the lateral head displacement by 27 percent (6.8 cm).