Structural FEM analysis of a Battery Electric Vehicle

This project focuses on the development of the passive safety components of a new type of Battery Electric Vehicle which tries to be a sort of market mover both from structural and material points of view. The most difficult job is to obtain low deceleration perceived by the occupants, since trying to be as lighter as possible, this is a very small vehicle, hence it does not have much space to decelerate and to absorb the energy of the crash, therefore also the choice of the materials is crucial. For what concern the chassis, it is inspired to F1 cars of the '80s: those race cars were the pioneer of a composite survival cell, the same concept as the one that we found on today's F1 cars. This is because structures like this made of composite material are extremely light but equally strong and they absorb in a very good manner the energy of possible crash. This cell is composed by two parts: the underbody and the upperbody, both in composite material so they are glued together on all the perimeter. Regarding the material, the composite is made by two components forming a sandwich because it consists of a core of honeycomb that increases the thickness, and on both sides externally there is a number of composite layers. The project is organized as follows: firstly, starting from the CAD, the model has been completed and improved from structural point of view, because at the design stage it was not complete: all the passive safety components were missing. Than the preliminary analysis of the chassis started. The first analysis performed was the modal one, to understand the behaviour of the chassis and its performances. After that, the stiffness evaluation has been computed both from torsional and bending points of view, in order to have a comparison with existing vehicles. Lastly, the crash test following the FMVSS 208 has been performed in order to model and size the front rails and the crash absorbers to lower as much as possible the deceleration perceived by the occupants, and to evaluate if the battery fastening systems were compliance with the requirement of the safety standards. The obtained results for what concern the NVH performances were satisfactory since the chassis has no resonnance with the vibrations coming from the road. Also the chassis stiffness results were above expectations since they were better than today's comparable cars, but the rear frame, which is the critical part of the chassis, hence some improvements have been studied trying to reach the target. Instead, the results of crash simulation were not as good as the structural one since the acceleration perceived by the occupant were still too high with respect to the regulation, hence some possible modifications of the structure have been suggested.