| In recent years,all countries in the world are vigorously developing heavy-haul freight trains.With the improvement of loading capacity and operating speed,reducing dead weight and increasing load is the development trend of heavy-haul freight railways.Welded structure is an important connection mode of wagon body.If failure occurs,it will lead to serious accidents.Therefore,it is of great significance to improve the anti-fatigue performance of welded structure of wagon body and carry out lightweight design of wagon body on the premise of ensuring the fatigue life of welded structure of wagon body.In this paper,the body of a certain type of heavy-duty truck is taken as the research object,and the lightweight design considering the fatigue life of the weld is carried out.The main research contents are as follows:Firstly,the finite element modeling of the truck body was carried out using Hyper Mesh software,and the operating conditions and boundary conditions of the truck body were set according to AAR standard,and the static strength,stiffness and fatigue were analyzed using ANSYS software.The results showed that the von Mises stress under each operating condition was less than the allowable stress of the material.The torsion span ratio of the middle beam and the lower side beam of the wagon body meets the design requirements of the TB-T 3550 standard.The fatigue life of the checked weld meets the design requirement of6 million kilometers.According to the standard of TB-T 3115,the free mode analysis of the wagon body is carried out.The results show that the first order transverse bending mode of the wagon body is 21.207 Hz,which meets the requirement of more than 10 Hz.Secondly,it can be seen from the above analysis results that the von Mises stress of each part of the wagon body is far less than the allowable stress of the material,and the material is not fully utilized.Therefore,Opti Struct software was used in this paper to carry out topological optimization design of the wagon body bottom frame.The optimal topology of the underframe beam structure of the wagon body was obtained with the aim of minimizing the flexibility of the structure,and the optimized structure was redesigned to improve the material distribution of the beam structure on the premise of ensuring the original performance of the structure.Finally,the finite element analysis of the redesigned optimized body showed that the von Mises stress was still less than the allowable stress of the material.Isight software was used to optimize the size of the wagon body,and the design variables were selected according to the results of sensitivity analysis.The Kriging model between the quality,von Mises stress and weld fatigue life and the design variables was established,and whether the established Kriging model could be used for the subsequent optimization design was tested.Based on the established Kriging model,with the minimum body mass as the target,von Mises stress and weld fatigue life as constraints,the MLGA algorithm was used to optimize the size of the model.The static strength,stiffness,fatigue and modal analysis of the optimized wagon body show that the weight of the new wagon body can be reduced by 6.7% compared with that of the original wagon body on the premise of meeting the design requirements. |
