SUMMARY
Objective: Frontal crash accidents remain a significant factor in causing the preventable injury and fatality for child occupants aged 3 in China. Despite the increased public awareness and utilization of child restraint system (CRS), inappropriate installations still exist and lead to a potential to result in injuries of head, thorax and abdomen regions of child occupants, especially when it comes to enhanced child restraint system (ECRS) with top tether. The current study focuses on the influence of top tether upon safety performance of ECRS with top tether in dynamic tests with different set-ups and explores the relationship between inappropriate installation of ECRS with top tether and the injury potential of child occupants aged 3 in a frontal crash. Methods: A testing scheme including 4 dynamic tests was devised to ascertain the extent to which the top tether affected the accelerations of thorax, the abdominal penetration and the head displacements. Different kinds of acceleration curves were employed to conduct the tests and to simulate the real status and situation of child occupants aged 3 in the CRS installed with top tether and without top tether respectively. Parameters of accelerations, abdominal penetrations, and head displacements were measured to analyze quantitatively the influence of inappropriate installations of ECRS with top tether under different conditions. Results: The safety performance of ECRS with the use of top tether was found better than that of ECRS without the use of top tether either in the normal condition or in the extreme condition. The test using the acceleration curves defined by regulations, the accelerations of thorax, abdominal penetrations, and head displacements of P3 manikin in the ECRS with the top tether connected to the anchor point revealed results that all met the requirements. While in the test using acceleration curves of the same kind, and when the top tether was not connected, the parameters measured displayed that the safety performance of the sample was worse than the former one. As for the tests using the more severe acceleration curves defined at will, it was more obvious that top tether could affect the function and safety performance of ECRS greatly, and the functional failure and severe damages occurred to the ECRS without the use of top tether. ECRS with the use of top tether was partly qualified even under the more severe conditions. Conclusions: Inappropriate installation of ECRS such as omitting the step of connecting top tether to anchor point could cause severe injuries and fatalities in frontal crash accidents. Effective measures should be taken to minimize the chances of inappropriate installations of ECRS.DOI:https://doi.org/10.33976/JERT.8.2/2021/2