Structural Analysis And Lightweight Research Of Pure Electric Van Frame

In recent years,with the rapid development of China's automobile industry,a series of energy and environmental problems caused by traditional internal combustion engine vehicles have becoming increasingly serious.And pure electric vehicles have become the breakthrough to alleviate the pressure of urban energy and environment with their advantages of energy conservation and environmental protection.After years of exploration and efforts,great progress has been made in the development of China's electric vehicle industry,but the research on frame design is mostly applied to passenger cars,and the frame of electric truck is mostly transformed from the frame of internal combustion engine trucks.However,electric vehicles are powered by electric motors and batteries,and their installation forms are different from those of internal combustion engine vehicles,the external excitation to the frame is also different.Moreover,the frame quality of internal combustion engine vehicles is generally heavier,which will seriously affect the cruising range of electric vehicles.Therefore,it is necessary to carry out finite element analysis on the frame of pure electric trucks to verify the rationality and safety,and on this basis,lightweight design is carried out to improve its endurance mileage.This paper takes a pure electric van truck produced by Kunming Bus Manufacturing Co.,Ltd.as the research object.The finite element static and modal analysis are carried out,and on this basis,structural improvement and lightweight design are carried out.The main research contents are as follows:(1)The stress and strain of the frame under full load bending,full load torsion,full load braking and full load turning are calculated,and the bending stiffness and torsional stiffness of the frame are checked with reference to the frame stiffness test method.The results show that the strength and stiffness of the frame can meet the requirements of the vehicle and have a large optimization space.However,the installation area of the power battery of the frame and the fourth horizontal section may be greatly deformed,so the structural improvement can be considered.(2)Through unconstrained free mode analysis,it is found that the frame avoids the external excitation frequencies that may be encountered during the driving process,so there will be no resonance phenomenon.At the same time,according to the mode diagram,it is found that the longitudinal beam between the fourth and the fifth beams and the fourth beams may undergo severe deformation,which needs to be improved.(3)The frame structure is improved according to the static and modal analysis.Then the thickness of the longitudinal beam,the third beam and the fourth beam are selected as design variables through mass sensitivity analysis.Under the premise of satisfying the bending stiffness,torsional stiffness and the first natural frequency of the frame,the optimization model of the frame quality is established.The mathematical form of the optimization model is determined by combining the Latin square test method and the response surface method.After verifying the mathematical form of the optimization model,the genetic algorithm is used to calculate the optimization values of the design variables.Finally,the lightweight effect evaluation and static and modal analysis of the optimized frame are carried out.The results show that the optimized frame can successfully reduce the weight of the frame by 6.7% while meeting the use requirements.