| With the continuous promotion of the national energy-saving and emission reduction strategy and the rapid development of the logistics and transportation industry,the lightweight design of logistics and transportation vehicles has become a key focus of relevant research.6061 aluminum alloy,as a lightweight material with low density and high specific strength,is widely used in the lightweight design of automobiles.However,research on its application to long gauge box semi trailers is still in its early stages.Firstly,this article focuses on the modular design of the carriage of a 12 meter long box semi trailer to improve its stiffness/strength,and designs a steel aluminum hybrid frame to assemble with it.Through finite element analysis,it was found that the designed long specification box type semi-trailer uses medium and high strength6061 aluminum alloy profiles to manufacture its carriage and frame bottom beams(supplemented by steel aluminum mixed assembly).On the basis of meeting the general requirements specified in QC/T453-2019 "Box Transport Vehicles",it breaks through the technical bottleneck of low elastic modulus of aluminum alloy materials and difficulty in meeting the overall structural stiffness standards caused by the combination of the long specification of the carriage,Moreover,its main load-bearing component uses 6061 aluminum alloy with good plasticity(i.e.easy extrusion forming),which is conducive to industrial mass production and manufacturing.Secondly,a finite element model of the entire vehicle environment was established in Hypermesh software,and its static and dynamic performance analysis was conducted.The analysis results under four extreme operating conditions of bending,torsion,braking,and turning show that the maximum stress of its structure is more than 18% lower than the allowable stress of the material,and its 7th to 12 th modal frequencies can avoid excitation from the engine and road surface,effectively avoiding resonance and having a large lightweight margin.Then,the topology optimization method is used to optimize the design of the cross section structure of the aluminum alloy profile used for the carriage’s load-bearing bottom plate,and the corresponding thick and thin material distribution is given more reasonably according to the bearing size of each part of the cross section structure,so as to reduce or even avoid unnecessary material waste.From the optimization results,it can be seen that after the cross-sectional structure optimization design of aluminum alloy profiles used for the representative carriage bearing bottom plate on the long specification box type semi-trailer,not only does the vehicle bottom plate lose 60 kg weight,with a lightweight weight reduction rate of 11.76%,but its stiffness also further improves.Finally,based on this,Hyperstudy was used to optimize the single objective size of the entire vehicle: first,partial factor design was used to screen the design variables,then the expandable grid sequence method was used to sample the test points,followed by the least squares method to fit the collected samples,and finally,the adaptive response surface method was used to complete the corresponding size optimization.The optimization design results show that the whole vehicle further reduces the weight by 190 kg on the basis of topology optimization.Compared with the original model,the total weight reduction is 250 kg,and the weight reduction rate is 8.8%,and the structural stiffness and mode are improved.From the above research results,it can be concluded that after modular design,topology optimization and size optimization,the van semi-trailer has achieved a good level of lightweight,which has practical guiding significance for the lightweight design and manufacturing of aluminum alloy van semi-trailer. |
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