Lumbar Load Estimation for a MADYMO FAA Hybrid-III Scalable Dummy

Abstract

The Federal Aviation Administration (FAA) has a number of regulations aimed at protecting occupants in the event of a crash. The Code of Federal Regulations, 14 CFR 25.562, describes the compliance regulation for transport category aircraft, with similar regulations for other types of aircraft in Parts 23, 27 and 29. One of the required tests is the dynamic impact with a Hybrid-II or a FAA Hybrid-III 50th percentile dummy seated on a 60-degree pitched seat, with an input deceleration/acceleration pulse acting primarily on the mid-sagittal plane of the dummy. In particular, an important compliance criterion is that the lumbar/pelvic load must be below the 1,500 lb (6,672 N) compliance limit. The objective of this study is to develop a reasonable approach to estimate the lumbar load tolerance for potential future expansion of lumbar load regulations for other dummy sizes such as an FAA Hybrid-III 5th and 95th percentile dummy. To accomplish this, the lumbar load measured with the Hybrid-II and the FAA Hybrid-III 50th percentile dummy when subjected to the 19 g rigid seat impact tests and simulations are correlated and discussed. The FAA Hybrid-III 50th percentile dummy is then scaled to the 5th and 95th percentile sizes based on GEBOD database. The dynamic behavior of the scaled FAA dummies in the 19 g sled simulation using an ideal acceleration pulse is then simulated and their corresponding lumbar loads are estimated. The dummy models utilized are obtained from the MADYMO crash test dummy database and the dynamic impact simulations are solved using the non-linear multibody dynamic solver, MADYMO. This study proposes the lumbar load tolerances for the 5th and 95th percentile sizes represented by the scaled FAA dummies by correlating their lumbar loads to the Dynamic Response Index (DRI) values. In this study, the lumbar load tolerance values for the 5th and 95th percentiles are proposed to be 870.4 lb (3,871.7 N) and 1772.9 lb (7,886.3 N), respectively. A comparison of the lumbar load tolerances proposed from this study and other sources is also presented.