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Technical Paper

Dynamic Modeling and Rollover Simulations for Evaluation of Vehicle Glazing Materials

The objective of this study was to mathematically model several proposed vehicle glazing materials using derived force-deflection characteristics, validate the models' dynamic behavior, and use the resulting glazing models in simulations of occupant dynamics during vehicle rollover. Simulations were performed with the three-dimensional, multibody dynamics program, the Articulated Total Body (ATB) model. The contact characteristics of side windows of tempered glass; polymethyl methacrylimide, also referred to as PMMI; and polycarbonate; as well as windshields from Ford Tempos and Jeeps, were developed from headform impact tests. These characteristics were first validated by performing simulations of the headform impact tests, and were then included in rollover simulations. Previously validated simulations of belted driver and unbelted passenger dynamics during an actual rollover accident were used as the baseline simulations.
Technical Paper

Pickup Truck Rollover Accident Reconstruction Using the ATB Model

To demonstrate the Articulated Total Body (ATB) model's capability to predict complex rollover accidents, a rollover accident was selected from the National Accident Sampling System (NASS) and simulated. This paper focuses on the simulation of the vehicle's dynamics which can in turn be used to specify the vehicle motion for occupant simulations. The selected accident case involved a pickup truck, crashing at high speed and completing three rolls. The pickup truck was modeled as a single rigid segment with fifteen contact hyperellipsoids rigidly attached to it. These hyperellipsoids were sized and positioned to approximate the exterior surfaces of the pickup truck. The force-deflection functions were defined based upon previous simulations of rollover tests. The initial conditions were defined to match the data in the NASS accident report as closely as possible.
Technical Paper

ATB Model Simulation of a Rollover Accident with Occupant Ejection

Computer simulations of occupant dynamics are ideal for conducting parametric studies evaluating injury countermeasures. A rollover accident was selected from the National Accident Sampling System (NASS) for simulation to validate the Articulated Total Body (ATB) model's capability to predict occupant dynamics during rollover accidents and to gain insight into injury mechanisms. Simulations of both the driver and passenger occupants which may be used in future countermeasure studies are performed. In the selected accident, a pickup truck rolled multiple times, the belted driver had minor injuries and the unrestrained passenger was ejected with fatal injuries. The body properties for both occupants were obtained using the Generator of Body Data (GEBOD) program based on their weights, heights, and sexes. The interior configuration of the vehicle compartment was modeled based on measurements taken from another vehicle of the same model.
Technical Paper

Comparison of Measured and Predicted Human Whole-Body Inertial Properties

Critical in vehicle crash simulations, human body data sets include mass, moments of inertia (MOIs), and ellipsoid size for each body segment, and location and resistive torque properties for each joint. The Generator of Body Data (GEBOD) program generates these human data sets for use in multibody programs. The objective of this study was to validate GEBOD estimates by directly measuring whole-body inertial properties of 69 volunteers and comparing the results with values calculated by the Articulated Total Body (ATB) model using GEBOD data sets. While the predicted whole-body center of gravity (CG) averaged within 1 cm of the measured values in the horizontal direction, vertically the errors were much larger. The predicted principal MOI were consistently 5%-30% lower than the measured values.