Analysis Of Bogie Frame Fatigue Life Based On Displacement Excitation In Time-Domain

Bogie frame is the key component of vehicle, but the analysis is still not able to resolve in the actual operation of crack initiation although there are a lot of existing structure fatigue fatigue analysis method. Based on the finite element model for vehicle, using the method of applying displacement irregularity on the rail contact point,ralize life calculation of Bogie frame,has the extremely important theory significance and wide engineering application valueBased on the comparation between different simulation methods on translating track irregularity power spectral density function to track irregularity in the time domain, the influence of the key parameters in inverse discrete Fourier transform on simulation results was analyzed. Then reasonable parameters were selected to simulate the vertical irregularity according to Chinese seven-parameter track spectrum in time domain.By calculating the life of a cantilever beam model in given load-time history with three different methods, i.e., the explicit algorithm, the implicit algorithm and the quasi-static superposition, the applicability of these methods in calculating the dynamic response stress was analyzed. The results show that the explicit algorithm is more suitable than the other two methods. A simplified vehicle model, in which carbody, wheelset, axle box, primary and secondary vertical damper, secondary lateral damper were all taken into account, was built. On the basis of seven-parameter track vertical irregularity spectrum, track irregularity loads, i.e., the displacement excitation, for eight wheels were obtained according their spatial relations. Then the loads were applied on the model, and the dynamic stress calculations were performed by utilizing Ansys LS-dyna and Ansys Transient, respectively. The results indicate that the stress amplitude and the mean stress obtained with these two methods are consistent well, while the implicit algorithm is more efficient. Paper implemented structure dynamic stress calculation based on the rail displacement excitation in time domain,widen the fatigue calculation way of dynamic stress.In order to investigate the influence of different damage accumulation theory on the calculating results of bogie frame fatigue life with present implicit algorithm and three damage accumulation theory including Miner, Morrow and DSM were applied. All the life calculations were performed in accordance with the BS standard and the IIW Standard, separately. The introduction of Morrow and DSM expands the choice of damage accumulation model in fatigue life calculation of bogie frame. The results show that different selection of mean stress weld standards and/or damage accumulation theory has a great impact on tpredicted fatigue life of bogie frame. Therefore, it is important to choose proper method in engineering applications.Present study provides a new idea for fatigue life prediction, while related research methods and conclusions are useful reference for further study.