Electric Vehicle Frame Modal Analysis And Optimization Design

The chassis of the electric cars, as a basal bearer, suffers from the impacts from roads, assembly parts of the car and loading mass. Besides, it also connects and fastens all the units of the car. Therefore, its strength, rigidity and safety are very significant in the general design of electric cars. Vibration can be reduced by choosing reasonable steel material and developing logical structure of the chassis in the process of design. Traditional designs mostly depend on designer’s experiences, simple stress analysis and modal analysis. Consequently, to improve the performance of the electric vehicle chassis, it is necessary to do modal analysis experiments and determine a reasonable frame structure.The computational modal analysis results of the electric vehicle frame which was developed earlier by Tangshan Municipal Key Laboratory of Electric Vehicles were the basis. In the project, sensors were installed on the frame logically and modal data were collected by large scale data acquisition and analysis system Premax-8018. Further more, a 3D motion simulation model of the frame based on the measured sizes of it is established. The data-driven points according to the positions where the sensors were set on the 3D motion simulation model were determined. The data of modal data acquisition and the driving points of the model were matched with each other, modal analysis was taken by Modal Genius Datablock to ensure the top ten natural frequencies and modes. Finally, the simulation model of 3D motion frame and data modal analysis results were imported into Modal Genius Simulation for 3D motion simulation to get real vibration of the frame. The results of modal analysis and the results of compute mode analysis were compared, in order to optimize the structure of the vehicle frame.The experiment shows that the optimized frame structure can effectively avoid the resonance phenomenon and reduce the noise. It meets the conditions of deflection, strength, stiffness requirements under the premise of reducing its volume, makes it the smallest mass to achieve lightweight design.