Research On Design And Application Test Of Chongqing As Metro Vehicle Car-body

Chongqing As metro vehicle is the first and unique kind of metro vehicle designed for mountain terrain in China.It has significant influence on reducing the cost of construction and operation,and improving the safety and operating efficiency of metro vehicle for mountainous and hilly terrain cities.Firstly,technical characteristics,car-body structures and optimal designs of Chongqing As metro vehicle are introduced.Compared with A type metro vehicle,lenghth of car-body and length between truck centers of Chongqiang As metro vehicle is smaller.Chongqing As metro vehicle has excellent climbing ability.Friction stir welding(FSW)method was used in the manufactureing of roof,sidewall,floor and endwall of Chongqing As metro vehicle car-body.Optimal designs of sections of profiles were carried out to reduce weight.And optimal designs of the joint were also carried out according to the requirements of FSW.Slab and girder structure of A1 alloy were used in the cab.Walking board on the roof and re-railling device were designed for inspection and repair.Secondly,the finite element numerical simulation was used to study the strength and mode of the head car car-body of Chongqing As metro vehicle.The results show that strength and stiffness of the head car car-body meet the requirements.Under calculation cases of static strength,the maximium of von Mises stresses are less than the yield limits of materials and welds.Equivalent bending stiffness of the head car car-body is 1.14×109N·m2,first order vertical bending frequency is 22.4Hz,The results satisfy the requirement of avoiding the natural vibration frequency of the bogie.The amplitudes of the maximium principal stress of the head car car-body are lower than the fatigue limit.Then,static strength test and modal test were carried out separately according to EN 12663-1:2010 and TB/T 3115-2005.The results of tests were analysed and compared with the results of finite element numerical simulation.The results show that the static strength of the head car car-body satisfies the requirements of EN12663-1:2010+A1:2014.The stresses of all the monitoring points are lower than the yield limits of materials and welds.High stress points are mainly located on the corners of the door,corbel and draft sill of the underframe.The first order vertical bending natural frequency of car-body is 20.2Hz,the first order transverse bending natural frequency of car-body is 29.6Hz,the first order rhombus natural frequency of car-body is 13.1 Hz,and the first order torsional natural frequency of car-body is 24.3Hz.The results of static strength tests and modal tests can be well matched,which indicated that the finite element model is valid,the structure of car-body is reseaonable and the strengths of car-body satisfy the requirements.At last,faigue property of the corbel was researched.Both finite elements analysis and fatigue test of the corbel were carried out.The fixtures of fatigue tests were designed according to the results of simulation.Under maximium static load,calculation stresses and tested stresses of the corbel have the same trends roughly.Calculation displacements and tested displacements also have the same trends.Calculation stresses and tested stresses have little differences,but calculation displacements are larger than tested displacements.The results of fatigue tests and life prediction both show that the fatigue life of corbel is much longer than 107 cycles.