Evaluating the Efficacy of Belt Positioning Booster Seat Design (High-back, Low-back and Height-less booster) in Frontal and Far Side Oblique Impacts

Principal InvestigatorAditya Belwadi, PhD, The Children’s Hospital of Philadelphia

Executive Summary

Project motivation: Child safety seats present a complex design challenge: to create a device that is easy to use, adjusts to children’s changing sizes, is capable of being properly fitted into the wide variety of vehicles, older as well as new, and is affordable. However, when it comes to vehicle seat belts as a design factor, booster seat design becomes particularly unique in that not only safety and ease-of-use but also comfort fit must be carefully considered for improved customer satisfaction, because occupants are restrained by vehicle seats unlike other types of child restraint seats. Belt-positioning booster seats are recommended for children who use vehicle seat belts as primary restraints but who are too small to obtain good belt fit. The vast majority of previous research evaluating the protection afforded by booster seats has been conducted in frontal crash conditions. However, the importance of other crash conditions- particularly side impact - in child occupant protection has received substantial attention lately. The FMVSS213 regulation has recently been proposed to be upgraded to include side impact protection and real world data suggests this crash direction is over represented in fatality and serious injury for children in child restraints and booster seats. CChIPS has studied this scenario in a line of research examining the performance of FFCRS in oblique lateral crashes (Hauschild et al, AAAM 2015). Little attention however has been placed on the performance of booster seats  in the crash direction. Thus, the current CChIPS project builds on this previous work, focuses on evaluating the effect of various routing configurations for booster seat designs on protection afforded in far-side impacts – both lateral and oblique crash modes, and compares the low back, high back, inflatable and heightless CRSs.

Specific aims: To Quantify the effect of various booster seat designs and belt routing strategies on booster seat performance in farside lateral and oblique impacts

Methods:

Step 1a: Selection of booster seats for the evaluation

A selection of seats based on inputs from the IAB and historical data from IIHS

Step 1b: Sled testing utilizing the Q6 anthropomorphic test dummy

Simulated frontal (0 deg), oblique (30 deg) and lateral (80 deg) tests on a sled system Step 2: Finite Element Simulation utilizing previously developed CChIPS finite element models

FE simulations varying the “D” ring position to understand belt rollout and injury metrics

Results and Conclusions:

Sled Testing:  40 sled tests were conducted using an instrumented Q6 with a hip-liner and abdominal pressure sensors. NHTSA’s 2017 NPRM test bench utilizing the FMVSS 213 test bench were used with two high-back, two low-back, one inflatable, one heightless and one no- booster seating condition. Seven seating conditions were evaluated in three PDOFs (0 deg, 30 deg and 80 deg) with each condition repeated twice. High-speed crash data, sled acceleration along with ATD kinetics were recorded. Kinetic data – head and chest resultant acceleration, HIC15 and chest deflection were all within IARV values as specified for frontal impact as part of the FMVSS 213 test standard. Kinematic tracking from high-speed video data revealed an increase in torso angle for the no booster and heightless CRS condition (from normal seating position) as compared to a decrease in torso angle for the other seating conditions. Further, in the heightless seating condition, we observed a “torso arching” phenomenon caused by the lap- belt riding onto the pelvis and the shoulder belt catching the neck causing the torso to arch. This also caused the abdominal pressure sensor (n=4) to pop as a result of this kinematic phenomenon.

Finite Element Modeling: In order to further examine the effect of the shoulder belt routing, the “D” ring location was artificially varied in a fully validated FMVSS 213 test bench model. Four conditions for “D” ring were selected: 213 bench, small sedan, large sedan and a pickup and evaluated with the Q6 ATD model for high-back, low-back and heightless seats. There was no significant difference found for the conditions in the low-back and heightless seats. However, for the high-back boosters it was found that altering the “D” ring position played a significant role in HIC15 and head resultant accelerations.

Comparison of low-back (LBB), high-back (HBB), and heightless boosters in frontal (0 degree), oblique (30 degree) and lateral (80 degree) impacts.

 

Project Team Member: Kristy Arbogast, PhD, Children’s Hospital of Philadelphia

Students: Evan Bisirri, Drexel University; Nhat Duong, Drexel University; Seth Fein, University of Pennsylvania; Jalaj Maheshwari, University of Pennsylvania

IAB Mentors: Keith Nagelski, Britax Child Safety Inc.; Michael Kulig, Calspan Corporation; Emily Thomas, Consumer Reports; Eric Dahle, Evenflo Company Inc.; Amanda Taylor, Federal Aviation Administration; Zine Ben Aoun, General Motors Holdings LLC; Julie Kleinert, General Motors Holdings LLC; Mark LaPlante, Graco Children’s Products Inc.; Jerry Wang, Humanetics Innovative Solutions Inc.; Jessica Jermakian, Insurance Institute for Highway Safety; Russ Davidson, Lear Corporation; Mladen Hume, Lear Corporation; Eric Veine, Lear Corporation; Arjun Yetukuri, Lear Corporation; Jon Sumroy, mifold; John Combest, Nissan Motor Company; Hiromasa Tanji, Takata Corporation; Schuyler St. Lawrence, Toyota USA; Barbara Birkenshaw, Volkswagen Group of America, Inc.; Uwe Meissner, Technical Advisor

About This Center

This Center is made possible through a grant from the National Science Foundation (NSF) which unites CHOP, University of Pennsylvania, and The Ohio State University researchers with R&D leaders in the automotive and insurance industries to translate research findings into tangible innovations in safety technology and public education programs.

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