Multidisciplinary Design Optimization Of EV Door Structure Based On Side Crashworthiness

As special part beyond the body-in-white, the door structure constitute the passenger living space together with the vehicle body. The door should provide right force transferring route and good protection to the passengers, and also has excellent performances in stiffness and vibration. For electric vehicle, the electrical safety, such as the deformation hazard of the battery package, should be considered. However, it’s an interesting challenge to satisfy all those performances mentioned above and reduce the weight of the door. Several responses of crash simulation, dynamic and linear static simulation are considered, a type of multi-objective optimization genetic algorithm is used to optimize the thickness of some panel parts of the door. The synthetical performances of the door are improved. The main works and innovation points are as follows:(1)The general process and tools which commonly used in finite element analysis are introduced, the basic FEA theory of the linear static simulation and free modal simulation are summarized. The finite element models about vertical stiffness and free modal are established respectively based on the relevant enterprise standards and industry regulations. The results of the simulation are obtained as the basis of the following multi-objective optimization.(2)The nonlinear dynamic mechanics theory involved in car crash simulation is overviewed. The finite element model of an electric vehicle under rigid column side impact condition is established, and then is solved and analized by LS-Dyna. The differences between electric vehicle and traditional vehicle are pointed out. The evaluating indicator of side crashworthiness, such as the total energy absorbed by the door, the acceleration of key points, the deformation of the frame where the battery package is settled are appraised as the basis of the following multi-objective optimization.(3)The theory of DOE(design of experiments), surrogate model and multi-objective optimization are summarized. The appropriate variables, responses and optimization objectives are chosen on the basis of the simulation mentioned above. The multi-objective optimal model is established with DOE and surrogate model. The model is further interfaced with a type of multi-objective optimization algorithm——NSGA-II to obtain the pareto front set from which the final optimal result can be chosen according to practical design principle, and the result is used in the finite element model to verify the surrogate model. With the optimal results, the vertical stiffness of the door conform to the standard of the enterprise, the first order modal frequency obtain certain promotion, the total energy absorbed by the door increase by12.3%, the acceleration of key point between the passenger seats decrease by15.4%.