An experimental seat for measuring external biofidelity in rear impacts

Kang, Y.; Moorhouse, K.; Stammen, J.; Bolte, IV, J.

The goal of this study is to design, construct, and evaluate a seat for measuring/evaluating external biofidelity in rear impact testing on a HYGE sled. In order to compare crash dummies and post-mortem human subjects (PMHS) the seat must be: (1) able to match the seat back rotation response, overall geometry, and padding/upholstery characteristics of a typical OEM seat, (2) capable of measuring how the occupant loads the seat during the event, (3) reusable (i.e., durable enough to withstand multiple tests), and (4) repeatable and reproducible. The geometry and moment-rotation properties of a typical passenger vehicle seat were resolved from the literature. The seat back, seat base, and head restraint were equipped with load cells to measure forces at 20 kHz. Dynamic analysis of a mass-spring-damper arrangement subjected to a moderate-velocity pulse (10.5 g, 24 km/h) was conducted to determine the spring constant K and damping factor C necessary to replicate the motion of a typical seat. Using the results of this analysis, two seats were constructed for attachment to the HYGE sled. A ballast Hybrid III 50th percentile male dummy was placed in each seat, with the load cells measuring the forces applied by the dummy. High speed video and accelerometers were used to verify seat back rotation and for inertial compensation of the load cells. Several sled tests were conducted with progressive versions of the seat until the performance criteria were satisfied. The final version of the seat was able to withstand multiple events without degradation in the repeatability of the seat back rotation response (CV < 5 %) and the two seats were reproducible when compared to one another (CV < 5%). Dynamic analysis of measured forces confirmed that the load cells were able to quantify the occupant loading on the seat. The next phase of this study is to test rear impact dummies and PMHS in this seat to generate internal and external biofidelity data in moderate-velocity conditions for use with the NHTSA Biofidelity Ranking System.

Year

Entry

2000

Yoganandan N, Pintar F, Stemper BD, Schlick MB, Philippens M, Wisman J. Biomechanics of human occupants in simulated rear crashes: documentation of neck injuries and comparison of injury criteria. Stapp Car Crash J. 2000;44:189-204. SAE 2000-01-SC14.

2005

Kim A, Sutterfield A, Rao A, Anderson KF, Berliner J, Hassan J, Irwin A, Jensen J, Kleinert J, Mertz HJ, Pietsch H, Rouhana S, Scherer R. A comparison of the BioRID II, Hybrid III, and RID2 in low-severity rear impacts. In: Proceedings of the 19th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 6-9, 2005; Washington, DC.

2001

Siegmund GP, Heinrichs BE, Lawrence JM, Philippens MMGM. Kinetic and kinematic responses of the RID2a, Hybrid III and human volunteers in low-speed rear-end collisions. Stapp Car Crash J. 2001;45:239-256. SAE 2001-22-0011.

1977

Hu AS, Bean SP, Zimmerman RM. Response of belted dummy and cadaver to rear impact. In: Proceedings of the 21st Stapp Car Crash Conference. October 19-21, 1977; New Orleans, LA. Warrendale, PA: Society of Automotive Engineers:589-625. SAE 770929.

2003

Bortenschlager K, Kramberger D, Barnsteiner K, Hartlieb M, Ferdinand L, Leyer H, Muser M, Schmitt K-U. Comparison tests of BioRID II and RID 2 with regard to repeatability, reproducibility and sensitivity for assessment of car seat protection potential in rear-end impacts. Stapp Car Crash J. 2003;47:473-488. SAE 2003-22-0021.