Statistical Assessment of Pretensioner and Load Limiter Effects on the Large Omnidirectional Child ATD Response in Frontal Impacts

Enhancing child occupant protection requires a clear understanding of how seatbelt restraint parameters influence crash injury metrics. Real-world vehicles mostly include pretensioner and load limiter technologies to mitigate injuries, but rear seat restraints often do not include these. The FMVSS No. 213 test bench closely represents current restraint systems but does not involve such active vehicle restraint features. This study explores the response of the Large Omnidirectional Child ATD to evaluate potential injury mitigation under FMVSS No. 213 frontal sled test conditions. A simulation-based full factorial design was implemented in LS-DYNA to vary pretensioner retraction, retractor load-limiting thresholds, and webbing payout, with injury measures including head acceleration, head excursion, chest compression, and abdominal pressure twin sensors (APTS). Statistical evaluation using analysis of variance (ANOVA) and Tukey-Kramer post-hoc tests quantified main and interaction effects. Pretensioners consistently reduced head excursion and acceleration, while load limiters lowered chest compression but increased excursion, illustrating a performance trade-off. Webbing payout behavior showed strong coupling to load-limiting thresholds, revealing notable parameter interdependencies. These results demonstrate that integrating pretensioners and load limiters into child restraint systems could yield meaningful safety benefits but must be optimized holistically to balance competing injury metrics. The study provides both empirical insight and a statistical framework for evaluating advanced restraint configurations in pediatric occupant simulations.