Analysis of child responses in CRS using child human FE model

Mizuno, Koji; Namikiri, Tatsuya

To investigate injuries to various body regions of a child in detail using a child restraint system (CRS), a finite element (FE) model of a 3-year-old child has been developed. Using this child FE model and Hybrid III FE model, the ECE R44 sled impact test simulations were conducted for three different types of CRS such as a 5-point harness, an impact shield and an ISOFIX CRS. For the child FE model, the whole spine flexed, whereas for the Hybrid III with stiff thorax spine, only the cervical spine and the lumbar spine flexed. As a result, in the 5-point harness CRS, the head down movement and its rotation were large for the child human FE model. The injury criteria of Hybrid III and child FE model were comparable in these CRS applications. In the impact shield CRS, the chest deflection was large. The head excursion was particularly small for the ISOFIX CRS.

The influence of belt slack of CRS on injury criteria was also examined from FE analyses. There was a relation between the ridedown efficiency and the chest acceleration. A slack seatbelt and harness in the 5-point harness CRS increased the injury risk. On the other hand, the injury criteria in the impact shield CRS with and without the seatbelt slack were comparable, which explains the low injury risks for children using the impact shield CRS in accidents.

Year

Entry

1997

Hummel T, Langwieder K, Finkbeiner F, Hell W. Injury risks, misuse rates and the effect of misuse depending on the kind of child restraint system. In: Proceedings of the 2nd Child Occupant Protection Symposium. November 12, 1997; Orlando, FL.165-180. SAE 973309.

1997

Lowne R, Roy P, Paton I. A comparison of the performance of dedicated child restraint attachment systems (ISOFIX). In: Proceedings of the 2nd Child Occupant Protection Symposium. November 12, 1997; Orlando, FL.71-85. SAE 973302.

2002

Iwamoto M, Kisanuki Y, Watanabe I, Furusu K, Miki K, Hasegawa J. Development of a finite element model of the total human model for safety (THUMS) and application to injury reconstruction. In: Proceedings of the 2002 International IRCOBI Conference on the Biomechanics of Impact. September 18-20, 2002; Munich, Germany.

2002

Oshita F, Omori K, Nakahira Y, Miki K. Development of a finite element model of the human body. In: 7th International LS-DYNA Users Conference. May 19-21, 2002; Detroit, MI.3-37–3-48.

1986

Kahane CJ. An Evaluation of Child Passenger Safety: The Effectiveness and Benefits of Safety Seats. Washington, DC: National Highway Traffic Safety Administration (NHTSA); February 1986. NHTSA Technical Report DOT HS 806 890.