| The development of public transportation is an important means to alleviate the problems of traffic congestion,and environmental pollution faced in China’s current urban development.The ART developed by CRRC Zhuzhou is a new rail transit system that subverts the traditional concept of rail transit.It is driven by electricity,runs in Multi-carriage marshalling and travels autonomously along virtual tracks.The ART is an option for the development of urban transportation due to their advantages such as flexible driving,large passenger capacity and high traffic efficiency.As the energy consumption during operation is directly proportional to the weight of the vehicle itself,the ART can reduce the vehicle’s body weight,reduce energy consumption,save manufacturing costs,and improve the vehicle’s handling performance and comfort.For smart rail trams,reducing the vehicle’s own weight can not only reduce energy consumption,but also reduce the maximum weight allotted per axle,thereby reducing the load on the rubber wheels and avoiding permanent damage to the ground.Since the weight of the car body account for about 30% to 40% of the weight of the ART,reducing the weight of car body is of great significance to the ART.The main work contents and results are as follows:(1)According to the car body structure characteristics and two-dimensional drawings provided by the company,the geometric model of the car body is established in CATIA,and its finite element model is built in Hyper Works.The structural performance parameters such as the strength,stiffness and low-order modal frequency of the smart rail tram body were obtained.And conduct a reasonable analysis of the structural performance parameters to lay the foundation for the subsequent optimization design of the car body.The analysis results show that the mechanical properties of the entire vehicle meet the design requirements and have a surplus,which has a certain optimization potential.(2)Using simcode in the Isight to integrate the ANSYS,the DOE is completed with the thickness of car body side wall and roof section as the design variable,and the parameters corresponding to static strength,stiffness and low-order modal frequency of car body are extracted as the output response.The approximate model for the lightweight optimization of each output response of the car body is established by using the second-order polynomial response surface model.The parameter sensitivity and the approximate model error are analyzed.Then confirm whether the approximate model accuracy of all output responses meets the engineering error requirements,in order to replace finite element model for subsequent optimization.(3)Based on the approximate model,the thickness of car body side wall and roof section as the design variable,the car body mass of the ART is seen as the objective function,taking the car body strength,stiffness and low order frequency as the constraints,and the optimization strategy combining the multi-island genetic algorithm and the gradient optimization algorithm NLPQL are used to complete lightweight optimization design of the car body.And an optimization scheme is proposed which is based on the optimization result and actual industrial production requirements.(4)Putting the optimization scheme into the original model to perform finite element analysis of bending conditions,torsion conditions and unconstrained free-modal analysis to verify whether the strength,stiffness and low-order modal frequencies of the car body meet the design requirements,Compared the simulation results with the result of optimization algorithms,it is to analyze the error of the optimization algorithm. |
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