Strength Design And Test Verification Of High Speed EMU Bogie Frame

As the running velocity grade increased, high frequency vibrations deteriorate the service conditions of the bogie frames. Fatigue strength design and reliability are essential issues of the research of the high speed electric multi-units (EMU) trains. Based on the welded structures fatigue design methods, the thesis introduced a complete frame of design process composed of construction of the fatigue database of the welded joints, loads obtained by numerical simulations that validated by line tests and enhanced test behch verifications.Partial fatigue database of welding joints were constructed in the thesis. Based on the anslysis of main welding design codes and comparision between FEM calculations and bench tests, norminal stress and structural stress design methods are feasible for frame design. Nominal stress FEM evaluation model with extra dense finite elements grids could meet the precision requirements. Relative errors could be limited below 10% compared with tests in critical areas.According to the requirements of strength evaluation and fatigue damage computation, vehicle dynamics simulation program were developed. The software is based on the multibody dynamics theory and implemented with object oriented C++ language. The bogie frame and carbody can be made flexible with small elastic deformation assumption. Open source routine OpenSceneGraph was used to implement 3D graphic interface as the rendering engine. The workflow was implemented by the MFC single document view architecture that can manage vehicle components, assemble and solve system equations.Comparation analyses between box-type and pipe-type boige frames by rigid flexible dynamics simulations and fatigue damage computations were taken. Vertical bending stiffness and torsion stiffness are closely interrelated with the mean value and amplitue of the dynamic stresses. According to the FEM harmonic analyses and fatigue damage computations of the variational tortional stiffness frame, the stiffness and strength design parameters have the identical optimization targets.The differences of the evaluation results about a pipe-type motor bogie frame under four test programs were studied in the thesis. Based on the analyses, optimized static test program was summarized with the costs and safety margin respected.Dynamic tests were studied in the thesis. The tests spectrum is generated by short term simulation data that corrected by tests data and extrapolated by usage factor based on damage equivalent principle. Serve charecateric index and deterioration function were introduced for facts that vehicle dynamic performances decrease during operation cycles. Virtual test bench model was developed to research design factors of physical test bench that can influence the channels synchronization and loading effects.