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Techniques for soil-tripped and curb-tripped rollover testing have been developed and reported in earlier papers. The tests reported in these earlier publications were conducted with a variety of vehicles launched at speeds close to 30 mph. Several additional soil-tripped rollover tests were conducted using a single model of mid-sized sedan launched at speeds ranging from 13 mph to 42 mph. This test series provided information about the minimum trip speed and the influence of trip speed on the characteristics of vehicle rollover. The results of this test series as well as the previously reported tests have been studied to obtain insights about minimum trip speeds, furrow characteristics, angular velocities, rollover distances, trip and post-trip decelerations and the influence of speed on rollover mechanics.

This paper describes a straight-forward, automated approach to performing sensitivity analyses using Monte Carlo simulation techniques. Probability distributions are assigned to key input parameters, and results are expressed in the form of probability distributions of each of the desired output parameters. With this technique, it is possible to obtain quantitative results regarding the probability of results being within selected ranges. The approach is fast and automated, and provides a rational basis for dealing with uncertainty and ranges of parameters in accident reconstruction analyses.

Research was undertaken to determine the effectiveness of rear-seat outboard occupant restraint systems in passenger cars, focusing on the overall efficacy of two-point rear-seat occupant restraint systems and comparing the relative performance of two-and three-point rear-seat occupant restraint systems. While a significant body of literature exists comparing the safety performance of various types of front-seat occupant restraint systems, very little comprehensive accident data analysis (i.e., using large volumes of data) has been conducted to date comparing the safety performance of rear-seat occupant restraint systems. For the study, the motor vehicle accident databases from five states were examined to determine the reduction in rear-seat occupant injuries associated with two-point and three-point rear-seat occupant restraint systems.

Analysis of accident data can provide important information for product design and regulatory policy. This paper will identify and describe some major sources of data for off-highway vehicle accidents and will discuss the methods for handling those data. Several examples of risk analysis will be described in detail, including an accident mode analysis for tractors and a comparative risk analysis for occupational injuries.

Two widely used computer programs developed for the analysis of vehicle collisions are CRASH and SMAC. This paper reviews stiffness parameters which are used in the application of these programs, and methods to select these parameters. The paper also introduces a rational method to select stiffness parameter KV for the SMAC program. The CRASH program expresses the vehicle force-crush relationship as FC = A + B*CR, where FC is the force per unit width, and CR is the vehicle residual crush. The “stiffness parameters,” A and B, define a linear relation with a zero-crush intercept. For collinear impacts, these parameters are used in determining crush energy, which in turn is used in determining changes in velocities of the impacting vehicles. Over the years, considerable effort has been expended by numerous researchers to determine A and B for a variety of vehicles, and a substantial body of vehicle crash test data has been developed and analyzed to this end.

A number of accidents involve a vehicle going off the edge of the road and becoming airborne. In these types of accident, the engineer is typically faced with the problem of estimating the velocity of the vehicle at launch, based on evidence defining the launch position and point of impact at the end of the flight. Two options have been available to evaluate the dynamics of such problems. The first is to treat the vehicle as a point mass, and use simple trajectory equations to define the flight path. This approach considers only the two translational degrees of freedom of the center of mass of the vehicle, and neglects effects of tire contact during launch. The second option is to carry out a full three-dimensional analysis. This approach treats the sprung mass of the vehicle as a rigid body, accounts for the four tire contact conditions, and possibly models the suspension and unsprung masses.