Analysis And Survey Of Small Lightweight Electric Vehicle Crash Safety

This thesis presents a study on the impact of vehicle electrification on vehiclesafety and offers solutions to ensure consistent safety performance, in both accidentprevention and protection during a crash. A general approach on vehicle safetyfundamentals provides the basis for imposing specific requirements caused by theminiaturisation and electrification of vehicles. The safety relevant characteristics of theelectric drive train components are introduced and the influence on the packagingpossibilities evaluated based on literature research. The survey of current electricvehicles provides an overview of the state of the art technology. A range of prominentmodels with noticeable specifics is introduced to presents measures taken to ensurevehicle safety under the new requirements. A detailed inquiry of the Smart ForTwo’ssafety performance provides further conceptions in crashworthy vehicle design andevaluates their feasibility in small lightweight electric vehicle design.The safety fundamentals of crash compatibility as well as the examination of theSmart ForTwo and Reva G-Wiz emphasise the importance of increased rigiditydemands for the small vehicles’ safety cell. Battery compartments in the vehicle floorand tunnel prevailed in both the vehicles surveyed and the general analysis. The surveyshows that so far safety performance on the level of standard motorcar certification hasonly achieved by vehicles longer than3100mm and kerb weight above1000kg. TheEuro NCAP rated only two all-electric models until now, awarding the3475mm longand1110kg heavy Mitsubishi i-MiEV with4stars.The results also show that good performance was only achieved by featuringadvanced restraint systems, in particular seatbelt pretensioners and adaptive airbags.Their significance is further confirmed by the crush space study addressing the reducedcrush zone space and increased kerb weight. The study finds higher stiffness and moreeven deformation response requirements for the crumple zone, which are feasible due todesign freedom enabled by electric drives. Moreover, a concept of flexible respectivelycrushable battery support is established as measurement to cope with the vehicle’sincreased kinetic energy due to the battery’s weight.