Research On Fatigue Reliability Of Rail Car Frame Under High Speed Impact

As the most important bearing part of the test rail car,the frame not only bears the influence of the counterweight block,the power system and other equipment,but also bears the influence of the random vibration load caused by the uneven track or the wear of the wheel train.Rail car impinges the cable,the frame also has to bear the impact of the cable blocking resistance.Under the action of the above load,the stress state of the frame is complex and changeable,and it is easy to produce different forms of damage.In view of the possible failure forms of the frame,the static and dynamic characteristics and fatigue reliability analysis of the frame are carried out by using relevant theories to understand the actual condition of the frame.The innovation and achievements of this paper are as follows:(1)Based on the energy method,the arresting dynamics model of rail car was established,and the change rule of impact resistance under different indicators of rail car was analyzed.Through the simulation of the project sample,the change law of the impact resistance when the maximum cable tension value is the minimum and the change law of the impact resistance when the stop distance is the minimum are studied respectively,and the change curve of the change curve of impact load is obtained.(2)The finite element model of the frame was established by using ANSYS Workbench platform,and the static analysis of the model was carried out.Based on the results of static analysis,the prestressed modal analysis of the frame is carried out,and the natural frequency and modal shape of the frame structure are obtained.The results show that the external factors such as track,gear train and rotor system can hardly cause the resonance of the frame structure.(3)On the basis of modal analysis,the transient response analysis of the frame under different indexes and different running speeds was carried out,and the stress concentration area and time-strain history curve of the frame were obtained.It is found that the frame is in elastic deformation stage and the deformation can be finally recovered.Under the same initial impact velocity,the frame shape variable with the shortest stopping distance is obviously larger than the frame shape variable with the minimum maximum cable tension.(4)Based on the obtained P-S-N curve of Q345 steel,combined with the fatigue cumulative damage theory,n Code software was used to carry out fatigue reliability analysis on the frame structure under different indicators,and the fatigue life and fatigue damage of the frame under corresponding working conditions were obtained when the survival rate was 99%.It is found that the fatigue damage of the frame is more serious and the fatigue life is lower when the stopping distance is the least.The analysis also provides a theoretical reference for the subsequent optimization design of the frame structure.