Simulation of crash events for an electric four wheel vehicle

Abstract

The diffusion of small size electric vehicles mainly designed for the urban context can significantly reduce the impact of personal mobility not only due to reduced energy consumption but also optimizing the use of parking and driving space in comparison with conventional vehicles. The solutions proposed on the market and at research level include innovations both in terms of layout (e.g. three and four wheel tilting vehicles) and in terms of powertrain, such as electric ones. The design, the sizing, the integration of battery system in vehicles are critical; this component directly determines overall performances, its mass and cost are relevant in comparison with the whole vehicle, it is subjected to ageing during use and, potentially, it can cause overheating or other failures in case of adverse events. This work is related to the analysis of a four-wheel electric vehicle mainly conceived for urban use; its size is compact and its dynamic performances are comparable to powered two wheelers due to tilting characteristics. The behaviour in case of crash is examined in order to estimate the solicitations on the battery and to verify any eventual implication on vehicle safety, at least for certain crash configuration. The activity included the definition of testing methods for electrochemical devices, a phase necessary to define the order of magnitude of acceleration events to which the single cells and/or the battery system have to be tolerant. Therefore, a full finite-element vehicle model has been defined starting from prototype vehicle design CAD, using realistic inertia and stiffness data also for battery compartment. The model has been used to simulate crash events against barrier and against other vehicles, repeating the analysis for a range of impact points and direction. The obtained estimation of deformation and acceleration values on battery system are presented.