| With the rapid development of the economy,the total of throughput of China’s ports has been increasing.Vehicle energy conservation and the emission reduction have received more and more attention to government and society,because the ownership of port transport vehicles and the annual increasing in vehicles have made China’s dependence on oil imports being rise.The vehicles used in the port are heavy trucks and more energy is needed to make it work.The fundamental problem is large energy consumption and the non-renewable energy can be greatly reduced if the oil truck is changed to a tram,the frame as the main bearing parts of the pure electric unmanned truck,its weight accounts for about 20% of the total weight of the vehicle.In order to satisfy the demand of the market,we study the frame lightweight and develop a new frame with a high degree lightweight.We follow the national call to improve the competitiveness of products and the enterprise efficiency.The research content of this paper is mainly divided into the following aspects:(1)Three-dimensional model was established according to the existing model,the part of the frame is retained after the modeling is completed and it is imported into Hyper Mesh for finite element modeling.The model is large,and a lot of rams will be occupied and calculation speed will be slow if we use the stereo mesh,so the two-dimensional mesh is used to extract the frame to the middle surface.In order to close to the real frame situation,the frame is meshed and the material properties of each plate are assigned,and the frame mesh is checked and improved.(2)The static strength of the frame is analyzed by Hyper Mesh software and the four common driving conditions of pure electric unmanned collector trucks.Constraints are applied and finite element analysis is carried out according to the different driving conditions of each working condition.The maximum stress of the frame for each working condition values was recorded.The values of the frame’s bending stiffness and torsional stiffness are also calculated at the same time.The analysis results show that the frame can meet the driving requirements under four working conditions.(3)The Opti Struct module was adopted to calculate the free mode performance of the frame of the pure electric unmanned truck and the former sixth-order modal frequency and mode shape diagram of the frame was obtained.Through analysis results,it can be seen that the frame of the pure electric unmanned collector truck will not resonate with the external vibration source.(4)The sensitivity analysis was used to analyse the frame plate,and the contribution analysis was used by Topsis.Ten components were selected for lightweight research according to the analysis results.The mobile least squares method was used to fit data on the mass,first-order modality,stiffness,and strength of the unmanned truck frame.Finally,the global response surface method was used to solve the problem,and the frame mass of the unmanned container carrier was reduced from 4105.55 kg to3921.47 kg,reducing the weight by 4.48%.(5)Finally,the multi-objective optimization of the unmanned container truck frame is carried out according to the previous approximate model.The multi-objective genetic algorithm MOGA algorithm was used for the optimization calculation to solve the multi-objective optimization Pareto solution set and plot the Pareto frontier curve.The highest set of indicators is selected as the optimal solution of this multi-objective optimization according to the comprehensive performance evaluation reference index.We ensure the strength and stiffness of the frame while reducing the frame mass by61.75 kg. |
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