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Citation
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Eggers A, Schiessler M, Ott J, Langner T, Wisch M. 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV); April 3-6, 2023; Abstract #: 23-0301, pp. 13p. Washington, DC USA: US National Highway Traffic Safety Administration, 2023 open access. |
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Abstract
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27th International Technical Conference on the Enhanced Safety of Vehicles (ESV): Enhanced and Equitable Vehicle Safety for All: Toward the Next 50 Years
https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000301.pdf
In frontal impact test procedures, the Hybrid III small female dummy is used to increase the protection of small car occupants. To address the increased thoracic injury risk for elderly occupants it is planned to introduce more stringent chest assessment criteria. However, previous studies raised concerns regarding the efficiency of criteria based on chest deflections measurements in the Hybrid III due to sensitivity of the measurements to variations in belt routing due to seat and D-ring settings. The seat in the most forward position and the D-ring in the highest position is mostly used in assessment tests. These settings result in a belt routing closer to the neck and reduced mid sternum chest deflection, which is not presentative of the actual peak deflection and therefore not meaningful to assess the chest injury risk.
The objective of this study was to investigate the effect of chest deflection sensitivity in the Hybrid III small female dummy in a generic sled test setup to variations of belt routings representative of contemporary vehicles. The study was complemented by sled tests with the THOR-5F in the same configurations to investigate the potential of this dummy as a future alternative. Furthermore, an analysis of field data was done to evaluate the preferred seat and D-ring settings of real small car occupants.
The results of the tests with the Hybrid III small female could confirm the findings from previous studies with shoulder belt routings representing contemporary vehicles. A routing with the belt closer to the neck showed a reduced sternal chest deflection in the Hybrid III small female. Corresponding tests with the THOR-5F showed a similar reduction of peak chest deflection at the maximum loaded IR-TRACC, but an increase at another location. Therefore, THOR-5F multi-point criteria might have the potential to address the issue of belt routing sensitivity.
The analysis of field data showed that small occupants representing the small female dummy in terms of height prefer to set the D-ring to the lowest position (driver and passenger). For the front seat passenger, the seat longitudinal and height setting mid/mid is preferred.
In conclusion the recommendations regarding seat and D-ring settings that were provided in previous studies can be confirmed. To enable an effective evaluation of chest injury risk with the Hybrid III small female the D-ring should be set to the lowest position for the driver as well as for the passenger side. For the passenger side the seat should be set to the mid/mid-position. Furthermore, these seat and D-ring settings are the most relevant preferred by small occupants based on field data. For additional improvement of chest injury risk assessment considering the specific needs of small female occueepants further research is recommended related to the THOR-5F and advanced multi-point chest injury criteria, which might be less sensitive to test parameters and resulting variation of belt routing. Repeatability and reproducibility of the chest deflection response of the THOR-5F dummy related the sensitivity of multi-point defection measurements should be further investigated and improved if necessary. |