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Technical Paper

Kinematic FCW System Modeling and Application for FCW Warning Strategy Evaluation

The theory is that there will be driving conditions in which the drivers are unaware of a potential crash and a warning system will allow them to, in some manner, avoid the accident or reduce the severity. In an attempt to develop an analytical understanding of Forward Collision Warning systems (FCW) for frontal impacts a 2-d mathematical/kinematic model representing a set of pre-crash vehicle dynamic maneuvers has been built.
Technical Paper

Application of Extreme Value Theory to Crash Data Analysis

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. Extreme value theory can be used to improve the predictive capabilities of the fitted function in the tail region. In this study the peak-over-threshold approach from the extreme value theory was utilized to show that it is possible to obtain a better fit of the tail of a distribution than the procedures that use the entire distribution only.
Technical Paper

A Stochastic Approach for Occupant Crash Simulation

Stochastic simulation is used to account for the uncertainties inherent to the system and enables the study of crash phenomenon. For analytical purposes, random variables such as material crash properties, angle of impact, human response and the like can be characterized using statistical models. The methodology outlined in this approach is based on using the information about the probability of random variables along with structural behavior in order to quantify the scatter in the structural response. Thus the analysis gives a more complete picture of the actual simulation. Practical examples for the use of this technique are demonstrated and an overview of this approach is presented.
Technical Paper

Vehicle-to-Vehicle Frontal Impacts: 2D Numerical Study

A 2D model for vehicle-to-vehicle impact analysis that was presented in an earlier paper [1], has been used to study several two-vehicle frontal impacts with different incidence angles, frontal overlap offsets, and mass ratios. The impacts have been evaluated in terms of energy and momentum change in the bullet vehicle and the target vehicle. Based on comparisons between pre- and post-impact longitudinal, lateral, and angular components of kinetic energy, and linear and angular momenta, the impacts experienced by the target vehicle and the bullet vehicle have been classified as collinear or oblique. These results have been used to propose a definition of frontal impact based on vehicle kinematics during a crash.
Technical Paper

Evaluation of the ES-2re Dummy in Biofidelity, Component, and Full Vehicle Crash Tests

This 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.” The biofidelity of the ES-2re is compared to that of the ES-2 and the WorldSID. Repeatability was also evaluated on the ES-2re based on the biofidelity test data. Additional pendulum tests were performed to assess the response of the dummy in oblique loading conditions, and results indicate that oblique loading from the front leads to significantly reduced rib deflections.
Technical Paper

Effect of Airbag Porosity, Mass Flow and Load Limiter on the 5th and 50th Hybrid Dummies in a 35 Mph Crash

Restraint systems play an important role in managing the energy of occupants during a crash event. Belt and airbag systems complement each other in order to gradually decelerate the occupant. However, the seating position of the 5th percentile female and 50th percentile male occupants forces the need to manage this energy in different ways. MADYMO simulation of a generic vehicle-restraint system with a driver side 5th and a 50th percentile Hybrid III dummy were done for a typical frontal impact. The belt system had a retractor/load limiter, but no pretensioner. The effect of airbag fabric porosity, inflation rate and seat belt load limiting ability were evaluated for both occupants. Parameters examined that affect system rebalancing to achieve the highest star rating were HIC and 3ms Chest acceleration.
Technical Paper


This paper discusses issues related to the Hybrid III dummy head/neck response due to deploying air bags. The primary issue is the occurrence of large moment at the occypital condyles of the dummy, when the head-rotation with respect to the torso is relatively small. The improbability of such an occurrence in humans is discussed in detail based on the available biomechanical data. A secondary issue is the different anthropometric characteristics of the head/neck region of the Hybrid III dummy when compared to humans. Different modes of interaction between the deploying air bag and the Hybrid III dummy’s neck are discussed. Key features of the dummy’s response in these interaction modes have been described in light of the laxity of the atlanto-occypital joint and the effect of the neck muscle pairs. Issues for improving the biofidelity of the Hybrid III dummy’s neck response due to deploying air bags are discussed.
Journal Article

Hybrid III Head/Neck Analysis Highlighting Nij in NCAP

Nij, a function of upper neck forces and moment, plays a dominant role in the vehicle's star rating under the new NHTSA NCAP front impact program. This is mainly due to an artifact in the mapping of the Nij into the “risk” value used in the star rating, and the fact that the neck region is not weighted appropriately to reflect its real world significance relative to the other body regions in the NCAP rating. New test data also show that compared with the 50th male driver Nij, the 5th female passenger Nij is significantly more challenging to contain and therefore it is more dominant in the star rating. This paper describes the Hybrid III dummy head and neck impact response and provides a method to determine the external force acting on the head. The force and its acting point on the head are determined from head acceleration, angular acceleration, and the upper neck forces.