The broad goal addressed in this endeavor is the improvement of the crashworthiness of cargo tank motor vehicles that carry hazardous materials. The purpose of the current research is to aid the understanding of the effects of a rollover crash on the “rollover protection devices” on the tops of these vehicles. The overall objective was to quantify the pre-impact dynamics of a rollover through full-scale experiments, that is, rollover crashes of loaded cargo tank motor vehicles. More specifically, the research was intended to verify the results of dynamic simulations conducted in a previous study. The Federal Motor Carrier Safety Administration (FMCSA) funded this effort as part of its response to a recommendation from the National Transportation Safety Board (NTSB) to “improve… the performance of the rollover protection devices on bulk liquid cargo tanks by modeling and analyzing the forces that can act upon rollover protection devices during a rollover accident.” This project began with a preliminary analysis of rollover crashes previously conducted by other organizations. That task was completed in 2002 and was reported to the FMCSA at that time. The broad summary of that task was that the measured quantities fell within the range of the corresponding simulated quantities. This report presents the major activity of this project, which was to measure the motions of cargo tank trucks as they rolled over. A small single-unit cargo tank vehicle was fitted with a roll cage so that it could withstand a crash, and it was rolled over four times. A cargo tank semitrailer was rolled over once. The five maneuvers leading to the rollovers were selected to approximate maneuvers that had been simulated in the earlier study. This provided a diverse set of rollover conditions and allowed comparison of the experimental to the simulated results. The first rollover was a relatively gentle one in which the truck barely turned onto its side. The final rollover, of the combination unit vehicle, was intended to be quite aggressive. Vehicle motion was recorded by an onboard inertial navigation system combined with a global positioning system (GPS) receiver. The crashes were recorded by video cameras from several angles on the ground and, in most cases, by one or more cameras on the vehicle. The semitrailer was instrumented with strain gages and string potentiometers to measure the deflections of the tank and the rollover protection devices during impact. The velocity measurements in this study will provide quantitative guidance concerning the performance requirements of rollover protection devices, which must bring the vehicle to a safe stop following the dynamic conditions measured in the moments prior to impact. The measurements of the semitrailer deformation will serve as a case study of how the particular design of rollover protective devices performed during a crash of known conditions. The vehicles obtained for the crashes were similar, but not identical, to some of those in the simulation study. Likewise, the maneuvers closely approximated but did not exactly duplicate those in the simulation study. Nevertheless, the experimentally measured values were compared with the results of the dynamic simulations. The simulations’ order of magnitude was certainly corroborated. The experimentally measured roll rates at the moment of impact were very much within the range of those calculated during the simulations. The data are presented in numerical and graphical form in the main text and the appendixes; CDs accompanying this report have videos of each crash and the raw motion and deformation data (see http://hdl.handle.net/2027.42/63013). (Author/publisher)
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