Research On Fatigue Reliability Of Bogie Frame For Metro Vehicle

The bogie frame of the railway vehicle in China are welded steel structure,which can greatly reduce the weight of the vehicle structure.However,with the increasement of the speed and the load and the enlargement of frequency range,especially the complex form of the welded joint,which makes the actual bearing situation of the frame structure becomes very bad,and resulting in welded joints at the main areas of structural failure.That is why we put forward higher security and reliability requirements.In this paper,the bogie frame of Beijing metro line 2 was taken as the object of study,and its fatigue reliability has been studied.The main research works are as follows:I.In this paper,the structural stress method proposed by Prof.Dong has been studied deeply,and the calculation formulas of its 2D and 3D element formulas were deduced.For the 3D element,the applicable method to calculate the membrane stress and bending stress were put forward,and an example was given to verify the grid insensitivity.II.Based on the establishment of the finite element model of the Beijing metro line 2 bogie frame(6-face element and 4-face element combined),the equivalent structural stress amplitude of key parts of fatigue was calculated,and the main curve method was used to evaluate the fatigue life.The results showed that the structure meets the requirements of operating mileage.III.With the combination of the calculation results of FEM and the measured results of dynamic stress testing,the load values souce from BS EN13749 were modified to make the intensity evaluation criteria more in line with the actual conditions of China railway line.IV.Reliability of the structure can be affected by many factors,the main factor is the premise to ensure the design of high reliability frame.By using the probability method to establish a parametric finite element model of the frame,and the geometry,material properties and loads were selected as random variables,the failure state function was established based on the maximum principal stress and the allowable stress of the parent material and weld joint.Finally the sensitivity of the reliability parameters of the frame was calculated with the help of Monte Carlo simulation,which provided a reference for the future optimization design;V.In this paper,the common structures were classified,which are in the same class with the Beijing metro line 2 bogie frame were selected as research object.Based on the simulation results and the data of the dynamic stress measurement which were accumulated by the structural strength testing laboratory of Beijing Jiaotong University.A standard dynamic stress measuring point arrangement scheme was proposed,which can provided reference for future experiments,also,save a lot of time and resources.