Study On Dynamic Ultimate Bearing Capacity Of Metro Vehicle End Beam Main Bearing Structure

As the running speed and the number of passengers are increasing continuously,the carrying capacity of metro vehicles should be gradually improved.In the design process,usually in the static bearing capacity as the basis,but due to dynamic elastic-plastic buckling and static elastic-plastic buckling(i.e.static strength)of the difference,so the design is too conservative,and wasting a lot of space,but also their material properties have not been fully.Therefore,it is of great significance to study the dynamic ultimate bearing capacity of the end beam structure,which is the main load-bearing structure in the car body structure.Firstly,the mechanical properties and constitutive model of base materials for metro vehicle body are studied in this article.By using the Instron standard electronic universal material testing machine and the split Hopkinson pressure bar(SHPB)device,the quasistatic tensile tests and dynamic compression test under high strain rates(about 2-110 s to4-110 s)of 6082-T6 aluminum alloy and SUS301L-ST stainless steel are carried out.The mechanical properties such as ultimate strength,yield strength,ductility and strain rate sensitivity are also analyzed.The corresponding constitutive equations are obtained by fitting the test results,which provides the material model and related parameters for the subsequent theoretical analysis and finite element simulation of the ultimate dynamic ultimate bearing capacity.Then,the ultimate bearing capacity of end beam structure is analyzed and simulated.According to the real end beam structure of B-type metro vehicle,the simplified design of the structure is carried out,and the solid model of end beam structure is created.Based on the super fold element theory,the ultimate bearing capacity of the end beam structure is theoretically analyzed.The theoretical prediction formula of the dynamic bearing capacity of the end beam structure made of stainless steel is deduced.And the influence of various parameters on the dynamic bearing capacity is also analyzed.A finite element model of end beam structure is created,and the finite element simulation analysis of quasi static compression and dynamic impact are carried out to obtain the extraction capacity and deformation,which are used to compare with the theoretical prediction results.Based on the simulation results of bearing capacity of end beam structure,the concept of dynamic reinforcement ratio is put forward,and the influence of impact velocity on dynamic strengthening ratio of end beam structure is analyzed.Finally,the ultimate bearing capacity test of end beam structure and the simulation analysis of the car body structure of the metro vehicle are completed.According to the measuring range of the test equipment,the reduction and simplification design of the end beam structure is carried out.The quasi-static compression test and dynamic impact test of the end beam scaled model are completed by means of electro-hydraulic servo multichannel loading test machine and drop weight test device.The bearing capacity of the structure under two conditions are obtained,which can also be used to verify the results of theoretical prediction and numerical analysis.In this paper,the end beam structure is applied to the metro vehicle,and the bearing capacity of the car body structure is simulated referring to the simulation process of the end beam structure.Based on the theoretical model,the ultimate bearing capacity of the end beam structure is optimized to achieve high load carrying capacity and lightweight.The dynamic bearing capacity of the optimized car body structure is compared with the static and dynamic bearing capacity before optimization to prove the rationality of optimization design.The bearing capacity under the dynamic impact conditions meet the vehicle crashworthiness standards.