Lightweight Design Of A Hybrid Vehicle Body

With the increasingly serious global energy and environmental problems,energy conservation and environmental protection has become the focus of national attention.Hybrid vehicles with low energy consumption,low pollution and other advantages have gradually become the main direction of the development of the traditional automobile industry.The research on the lightweight of the car body can effectively reduce the vehicle quality and prolong the mileage.The research object of dissertation was a hybrid electric vehicle independently developed by a company in Hebei Province.Based on the finite element analysis was of body-in-white,the lightweight research was carried out,and the fatigue life of the optimized body was estimated.The main research contents are as follows:(1)According to the drawings provided by the enterprise,the three-dimensional model of body-in-white is established,which is imported into ANSYS Workbench software by model parameterization,and the model is checked,simplified,netted and so on.Finally,the finite element analysis model of body-in-white is obtained.The static simulation analysis of the bending condition and torsion condition of the body-in-white was carried out to check the stiffness and strength of the body-in-white under the two working conditions.The results show that the stiffness of the body-in-white was slightly insufficient and the strength of the body-in-white meets the requirements of its performance.The free modal analysis of the body-in-white was carried out,and the first 18 free modal frequencies and modal arrays of the body-in-white were obtained.The calculation and analysis show that the common excitation frequencies caused by road surface,motor,tire and transmission shaft are effectively avoided and the resonance phenomenon is avoided.(2)Combined with the above finite element analysis,the new energy material SMC was used to replace the non-main stress zone of the car body,and the plate thickness of the body-in-white part was taken as the design variable.Through the sensitivity analysis,the design which has little influence on the performance of thecar body was deleted.The central composite design method was used to sample the design variables,and the Kriging model was used to construct the response surface.Taking the minimum body mass as the goal and the body performance as the constraint,the optimal solution was found based on MOGA genetic algorithm.After optimization calculation,the weight loss of body-in-white is 7.1kg,the performance of car body is improved,and the goal of lightweight is achieved.(3)The fatigue life of the optimized body-in-white was analyzed.The vehicle dynamics model was built by ADAMS software,the random road spectrum was selected according to the road information,and the load spectrum of key nodes of body-in-white was simulated by Adams software.Based on the material S-N curve and Miner fatigue damage theory,the fatigue life was analyzed in n Code fatigue analysis software,and the minimum fatigue life cycle times of body-in-white is2.702e+07,which meets the design requirements.Based on the analysis of the structural characteristic of hybrid electric vehicle body,this paper put forward a lightweight design scheme,which provides a certain reference value for the lightweight design of new energy vehicles in the future.