ABSTRACT
Studies conducted at the FAA Civil Aeromedical Institute have shown that when used in aircraft, automotive child restraint devices do not always provide the level of safety desired. Various factors that contribute to poor performance, such as seat belt anchor location, cushion stiffness, and child restraint device design features, were evaluated by a dynamic impact test program. To efficiently continue the research, a computer model was developed using MADYMO. Results of two of the impact tests were used to validate the model. Both test configurations utilized a typical commercial transport airplane passenger seat and a popular automotive child restraint device. These tests were considered representative of the extremes of child restraint device and occupant kinematics due to variance in seat belt anchor location. Details are presented of the test parameters and geometry, as well as cushion and restraint system properties. Test and modelling results for these two impact conditions are summarized and compared. Parametric studies were then conducted that used the model to investigate the effect of cushion stiffness, belt anchor spacing, and initial belt tension.
Subject(s)
Accidents, Aviation , Models, Theoretical , Protective Devices , Child, Preschool , Humans , Manikins , Safety , Seat BeltsABSTRACT
We study shape-induced variability in the scattered intensity from randomly oriented nonspherical particles. Up to 21 different Chebyshev shapes contribute to defining a shape-induced standard deviation about each of the mean nonspherical intensity vs angle curves shown in part 2 of this series. Bands of shape-induced variability (defined as plus and minus one standard deviation) for six size intervals within the size parameter range 1
ABSTRACT
The calculated angular scattering properties of over 250 randomly oriented nonspherical Chebyshev particles are examined for the effect of three factors: size; concavity vs convexity; and amount of deformation from a sphere. Both shape and size averaging are performed to reveal general features of the angular scattering not discernible for particular shapes and sizes. Comparisons with a comparably extensive experimental study published by Zerull in 1976 reveal remarkable qualitative similarities, even though Zerull used greatly different shapes from ours. This augurs well for the eventual development of a general theory of nonspherical scattering, although such a theory must account for concavity in addition to the amount of deviation from a sphere; and it cannot be entirely deterministic, as the third paper in this series will argue.
