Abstract
Keywords: compatibility, numerical simulation, frontal impact, simplified modelling, car-to-car impact
The University Research Project "Mitigation of Real World Injury Risk in Frontal Impact" at TU Berlin in cooperation with Ford Werke GmbH aims at the optimisation of a vehicles' compatibility in a frontal impact against any vehicle in a fleet of possible opponent vehicles. This requires the definition of a metric, which describes the feature "compatibility" quantitatively (preferably on a linear scale). We consider the optimum in compatibility to be reached, when impacts of the vehicle under consideration with every other vehicle statistically leads to minimal injuries of the passengers in both vehicles. Opponent vehicles are represented according to their share in the fleet. Impact configurations are weighted with their occurrence in accident statistics. Car occupancy is represented by weighting factors (male - female, large - small, number of persons in the car). Injuries are weighed by the costs they induce.
A fleet modelling technique was developed, which allows representing the structural behaviour of possible opponents with adequate accuracy. Highly refined vehicle models, which were originally intended for development purposes, were used to derive simplified models which maintain all features relevant for the impact mode but allow for radically reduced computational effort in order to make the assessment of a very large number of impact scenarios feasible. The model of the vehicle under consideration is also simplified, but keeps all features defining its compatibility in a frontal impact. Injuries are being estimated by applying the computed cash pulse to MBS-models of the occupants, the interiors of the vehicles and their restraint systems.
Based on various scenarios of European fleet composition, projections for compatibility are being investigated (including variations in vehicle stiffness, geometry of relevant structures, fleet attrition, ageing populations etc.). An outlook is given, how this methodology can be used to optimise the frontal vehicle stiffness in order to define a "perfectly compatible" vehicle for a given vehicle fleet quite early in the development process of a vehicle programme.