United States Department of Transportation
i
Evaluation of a Head Injury Criteria Component Test Device
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2004-11-01
[PDF-1.59 MB]
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Abstract:Aircraft seats that are certified to meet the requirements of 14 CFR Parts 23.562, 25.562, 27.562 and 29.562 must protect the occupant from serious head injury as defined by the Head Injury Criterion (HIC). Currently this is demonstrated during a dynamic sled test that includes a 50% male-size test dummy, the seat, and any surrounding aircraft structure that could be impacted by the occupant's head. To reduce cost and expedite design and certification, a means of demonstrating compliance using a component-level test was desired. A project to develop a component test method was initiated by the FAA Technical Center's Materials and Structures Branch, under contract to the National Institute for Aviation Research (NAIR) at Wichita State University (WSU). This effort resulted in the development of the HIC Component Test Device (HCTD) as described in FAA report DOT/FAA/AR-02-99. The HCTD consisted of a test dummy head attached to a pivoted arm that is propelled in an arc by an air actuator. The device was transferred to CAMI in Dec. 2002 for evaluation and further development. A series of sled and component tests were conducted to evaluate the HCTD's predictability, repeatability, and degree of correlation with the sled tests. The device produced head impact velocity and HIC results that were very repeatable when impacting surfaces with consistent force/deflection properties. A relationship for impact velocity versus firing pressure was also developed. Several representative aircraft interior surfaces were tested at various head impact velocities and impact angles. These surfaces included padded rigid walls, unpadded composite walls and wall sections, and energy absorbing and non-energy absorbing seat backs. When the results for the two test methods were compared, impacts with some surfaces showed correlation and some did not. Impacts with padded rigid walls correlated well, while impacts with stiff walls or wall sections did not. Impacts with seat backs yielded mixed results with correlation being dependent on the stiffness of the area of the seat back being impacted. A MADYMO computer model was developed to investigate factors that could improve correlation. Further investigation is necessary to determine if modifications to the device could improve the degree of correlation.
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