Repeatability and reproducibility of upper thorax reponses of THOR-50M ATDs

Hikida, Kazuki; Maehara, Kazunori; Mikami, Hidenori; Mae, Hiroyuki

Affiliations

¹Honda R&D Co., Ltd. Automobile R&D Center, Japan

Abstract

Anthropomorphic test device (ATDs) used for injury assessment are continuously being developed to enhance their biofidelity. For frontal crash testing, the Test device for Human Occupant Restraint (THOR-50M) ATD is being considered as the next injury assessment device in place of the current Hybrid III 50M (HIII-50M) ATD. Due to improved biofidelity and advanced instrumentation, the THOR-50M ATD has been developed to improve the assessment of injury measures in comparison to HIII-50M ATD. This study evaluated the THOR- 50M ATD‟s repeatability and reproducibility (R&R) of the thorax, and compares the findings to that of the HIII-50M ATD.

The thorax deflection of THOR-50M and HIII-50M were measured respectively. For three THOR ATDs, the upper thorax qualification test was conducted three times by the present certification procedures. For five Hybrid III ATDs, the thorax impact test was conducted three times by the Low Speed Thorax Impact Test Procedure. The coefficient of variation (CV) of thorax deflection was calculated to evaluate the R&R in thorax response. In addition, the thorax deflection was converted into injury risk probability because the THOR-50M utilizes different risk curves, measurement equipment, and measurement points from the HIII-50M. In the HIII-50M ATD, the characteristics of ribs are certified as a way to improve the R&R. In order t o investigate the effect of the characteristics of ribs on the THOR‟s upper thorax response, the ribs thickness was measured for three THOR ATDs. Moreover, a lumbar spine is one of the components that influence on THOR‟s upper thorax response. The bending stiffness was evaluated by lumbar spine flex joint bending test. Two THOR ATDs attached with the thickest and thinnest ribs were selected. The thorax deflection was measured by upper thorax qualification tests.

It was found that the CV of THOR-50M was larger than that of the HIII-50M. Also, it was found that the upper X-axis and Z-axis thorax deflection of the THOR-50M with the thinnest ribs was about 5 % larger than that of the THOR-50M with the thickest ribs. In the upper Z-axis thorax deflection, the difference between two ATDs attached with the same ribs was about 7%

The thorax of THOR-50M has more complex structure than that of HIII-50M, so the R&R of THOR-50M might be lower than that of Hybrid III in thorax response. It is believed that the THOR-50M‟s upper thorax deflection is influenced by rib cage stiffness which depend on the thickness of ribs. In order to improve R&R, it is recommended that rib thickness be certified, as is done for the HIII-50M. The bending stiffness of THOR‟s lumbar spine might have a contribution to increasing Z-axis deflection.

In conclusion, a certification method for guaranteeing rib characteristics is required for minimizing the variation of the upper X-axis and Z-axis thorax deflection. For future studies, the influence of other THOR- 50M ATD components on the upper thorax deflection should be investigated.

Links

URL: http://indexsmart.mirasmart.com/25esv/PDFfiles/25ESV-000280.pdf

Cited Works (7)

Year	Entry
2000	Xu L, Jensen J, Byrnes K, Kim A, Agaram V, Davis KL, Hultman RW, Kostyniuk G, Marshall ME, Mertz H, Nusholtz G, Rouhana S, Scherer R. Comparative performance evaluation of THOR and Hybrid III. In: Proceedings of the SAE World Congress. March 6-9, 2000; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 2000-01-0161.
2007	Martin PG, Shook L. NHTSA’s THOR-NT database. In: Proceedings of the 20th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 18-21, 2007; Lyon, France.
2004	Shaw G, Lessley D, Bolton J, Crandall J. Assessment of the Thor and Hybrid III crash dummies: steering wheel rim impacts to the upper abdomen. In: Proceedings of the SAE World Congress & Exhibition. March 8-11, 2004; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 2004-01-0310.
2000	Xu L, Agaram V, Rouhana S, Hultman RW, Kostyniuk GW, McCleary J, Mertz H, Nusholtz GS, Scherer R. Repeatability evaluation of the pre-prototype NHTSA advanced dummy compared to the Hybrid III. In: Proceedings of the SAE World Congress. March 6-9, 2000; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 2000-01-0165.
2011	Ridella SA, Parent DP. Modifications to improve the durability, usability and biofidelity of the THOR-NT dummy. In: Proceedings of the 22nd International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 13-16, 2011; Washington, DC.
1977	Foster JK, Kortge JO, Wolanin MJ. Hybrid III: a biomechanically-based crash test dummy. In: Proceedings of the 21st Stapp Car Crash Conference. October 19-21, 1977; New Orleans, LA. Warrendale, PA: Society of Automotive Engineers:975-1014. SAE 770938.
1998	Rangarajan N, Shams T, McDonald J, White R, Oster J, Hjerpe E, Haffner M. Response of Thor in frontal sled testing in different restraint conditions. In: Proceedings of the 1998 International IRCOBI Conference on the Biomechanics of Impact. September 16-18, 1998; Göteberg, Sweden.513-525.