A parametric model obtained by fitting a set of data to a function generally uses a procedure such as maximum likelihood or least squares. In general this will generate the best estimate for the distribution of the data overall but will not necessarily generate a reasonable estimation for the tail of the distribution unless the function fitted resembles the underlying distribution function. A distribution function can represent an estimate that is significantly different from the actual tail data, while the bulk of the data is reasonably represented by the central part of the fitted distribution.
View Article and Find Full Text PDFStapp Car Crash J
November 2017
Statistical methods, using the entire time-history, can be used to assess the impact response of an ATD (Anthropomorphic Test Device) in terms of its repeatability and reproducibility. In general, the methods generate a correlation relationship described as shape, magnitude and phase-difference between two time-histories' in a given set of similar tests: for repeatability the relationship it is for the same ATD, for reproducibility it is for different ATDs of the same design and for biofidelity it is a relationship between ATDs and biomechanical response data from a series of human surrogate impact tests. The method uses the phase relationship to minimize the difference between any two time-histories through an alignment procedure and the magnitude and shape correlations are used to generate a parametric evaluation of the differences between any two time-histories, or set of time-histories.
View Article and Find Full Text PDFThe objective of this study is to analytically model the fatality risk in frontal vehicle-to-vehicle crashes of the current vehicle fleet, and its sensitivity to vehicle mass change. A model is built upon an empirical risk ratio-mass ratio relationship from field data and a theoretical mass ratio-velocity change ratio relationship dictated by conservation of momentum. The fatality risk of each vehicle is averaged over the closing velocity distribution to arrive at the mean fatality risks.
View Article and Find Full Text PDFOne method of understanding the general mechanical response of a complex system such as a vehicle, a human surrogate, a bridge, a boat, a plane, etc., is to subject it to an input, such as an impact, and obtain the response time-histories. The responses can be accelerations, velocities, strains etc.
View Article and Find Full Text PDFThis technical paper presents the results from tests conducted with the ES-2re, a version of the ES-2 side impact dummy that was modified by the National Highway Traffic Safety Administration (NHTSA) to improve its performance in crash tests. Through the series of biofidelity tests conducted on the ES-2re, described in International Standards Organization (ISO) Technical Report (TR)9790 (1999), the OSRP observed a final overall biofidelity ranking of 4.1 for the ES-2re, which corresponds to an ISO classification of "marginal.
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