Principal Investigator: Yun Seok Kang, PhD, The Ohio State University

WHAT IS THE BACKGROUND FOR THIS PROJECT?

LATCH is a standardized method of attaching child seats to vehicle seats. The top tether provides an excellent safety advantage when used properly, by reducing forward displacement of the child’s head and, therefore, reducing the likelihood for injury. However, the effectiveness of top tether location on the dynamic load in a side impact scenario has not been thoroughly pursued, so this became the aim of our project.

HOW DID YOU INVESTIGATE THIS?

We wanted to see the effect of various parameters, such as seat stiffness, CRS design, and seat contour, on top tether loads. We created a finite element model that could simulate side impact conditions using the FMVSS 213 side impact test bench and a forward-facing CRS with a Q3S ATD model. We used a LATCH system to attach the CRS and measured lower anchor and top tether loads. We also recorded ATD kinematics for the simulation. Then we performed a parametric study to find out which parameters affect the top tether load, as well as the lower anchor force. We found that the top tether reduced lower anchor loads in both lateral and oblique impacts and that the top tether reduced CRS rotation and lateral head excursion of the ATD head in various testing conditions.

WHAT ARE THE NEXT STEPS FOR THIS AREA OF RESEARCH?

With the completion of this project and previous CChIPS research, we now have information on the importance of top tethers for the side impact and frontal impact scenarios. Next steps should involve merging this information to quantify the maximum force or maximum load on the top tether – the “worst case scenario” that can be applied to the top tether during impact. This information can be utilized by CRS and vehicle manufacturers to ensure these maximum loads are not exceeded and child occupants are optimally protected.

Project Team Members

Hyun Jung Kwon, PhD, The Ohio State University; Rakshit Ramachandra, PhD, The Ohio State University

Student

Jared Seidel, The Ohio State University

IAB Mentors

Keith Nagelski, Britax Child Safety, Inc.; Eric Dahle, Evenflo Company Inc.; Julie Kleinert, General Motors Holdings LLC; Barbara Birkenshaw, Volkswagen Group of America