Principal Investigator: Jalaj Maheshwari, MS, Children's Hospital of Philadelphia

Harness misuse, which includes loose harness straps and disengaged chest clip, accounts for more than 50% of critical misuse cases in infant, rear-facing, and forward-facing child restraint systems (CRS). This study examines the effects of 5-point harness misuse on the kinematic and kinetic response of a Q3s anthropomorphic test device (ATD) restrained in a forward-facing CRS on the new FMVSS 213 NPRM test bench.

WHAT WAS THE PURPOSE OF THIS PROJECT?

The efficiency of CRS is contingent on proper installation and use. Common CRS misuses involving the 5-point harness include loose straps and chest clip errors. We conducted this sled test-based research with “real-world” misuse scenarios where the harness is not set at the required tightness and the chest clip is not positioned at its correct position or is disengaged entirely. We sought to test scenarios that could help guide future CRS misuse prevention efforts.

HOW WAS THE RESEARCH CONDUCTED?

The Q3s ATD was restrained in a forward-facing CRS on the FMVSS 213 NPRM side impact test bench, subjected to far-side impacts. Harness misuse cases, including harness slack (tight and loose harness) and chest clip misuse (engaged in ideal and low positions; disengaged clip) were tested. We conducted a repeat test for each condition for a total of 12 tests and compared injury metrics across all conditions.

WHAT DID YOU FIND?

Lateral head excursion was significantly greater for the loose harness as compared to the tight harness. The ATD’s head rolled out of the protective side wings of the CRS, irrespective of the harness slack condition tested. The degree of rollout varied: when the harness was tight, the ATD rolled along the CRS’s side wing; when the harness was loose, the head was completely exposed outside the confines of the CRS. When the CRS cannot contain the ATD’s head, there is greater potential for head strike and injury. The chest clip misuse conditions generally had higher injury metric values than the ideal conditions.

HOW ARE THESE RESULTS APPLICABLE TO INDUSTRY MEMBERS?

By studying the potential implications for child injury based on real-world CRS use, we can develop better ways to prevent their misuse. The study provides data to justify future initiatives to prevent CRS misuse through both engineering advancements and/or public education efforts.

WHAT’S NEXT?

The next step would be to include investigation of near-side impacts where excess lateral head excursion and head rollout could result in head contact with the vehicle structures.

Head rotation and roll-out observed in far-side impacts for the tight harness (left) and loose harness (right) conditions.

Co-Investigators

Madeline Griffith, MSE, Children’s Hospital of Philadelphia; Declan Patton, PhD, Children’s Hospital of Philadelphia

IAB Mentors

Jonathon Gondek, Calspan Corporation; Daniel Wells, Calspan Corporation; Emily Thomas, Consumer Reports; James Fitzpatrick, Graco Children’s Products Inc.; Mark LaPlante, Graco Children’s Products Inc.; Jerry Wang, Humanetics Innovative Solutions Inc.; Curt Hartenstine, Iron Mountains; Erin Hutter, National Highway Traffic Safety Administration; Steve Gerhart, Nuna Baby Essentials, Inc.; Russ Davidson, Lear Corporation; Uwe Meissner, Technical Advisor