Mechanical Safety Analysis Of Pure Electric Vehicle Batteries In Vechicle Collision Accident

Well passive safety of the vehicle plays an effective role in the protection of the vehicle itself and the occupant. Passive safety design of electric vehicles draws on traditional fuel vehicles in general, but has its own characteristics. As important components of electric vehicle, passive safety design of batteries must be considered.Firstly, critical theory of finite element method in the field of impact dynamics was studied to provide theoretical bases for the next efficient mesh. Research contents include numerical equations of impact problem, contact nonlinearity problem and material nonlinearity problems. Solder joint simulation, time step selection of explicit formulation algorithm, unit selection and hourglass control were also studied in the specific simulation work.We are focused on establishing highly efficient finite element model of the vehicle, which is used for the further front crash simulation analysis. Firstly, focused on energy-absorbing structures and the impact force transmission path of vehicle body front, we simplified the electric vehicle BIW. Next, by selection of unit type, control of unit size and shape, simulation of spot welding and definition of contact type, a finite element model of the vehicle was established. The simulation time for vehicle collision is compressed in less than an hour. Finally, the efficient FEM model was used to carry on the crash simulation according to the conditions of 100% overlap rigid wall frontal crash test in C-NCAP. The simulation data result shows a perfect agreement with that of the real vehicle crash test. The validity of the finite element model of vehicle is verified.Using the finite element model, further simulation was carried out to analyze crash safety of battery. Firstly, an oblique rod is added to the battery frame structure to optimize distribution of stress. The result of the simulation analysis indicates that the harmful tumbling and displacement of battery are prevented significantly. Secondly, aimed at reducing excessive acceleration of battery and preventing its intrusion into passenger cabin, hot forming steel is applied to the longitudinal beam’s extension. Simulation result with the new design shows that the extension part’s deformation is improved significantly. As a result, battery acceleration is reduced drastically and its intrusion into the passenger cabin is zero. It is concluded that crashworthiness of battery in the field of mechanics can be improved significantly through new design process using hot forming steel.