| The safety of rolling stock is highly affected by fatigue problem of welded structure of wagon body. Once fatigue failure occurred, it will lead to heavy problem. For fatigue prediction of welded structure is faced not only the general problem of unwelded structure, but also the special difficulty resulted from weld arts. So, study of fatigue acts for wagon body is very important. In this thesis, the contents are mainly focused on the following three subjects:Firstly, this thesis researched fatigue prediction principle for welded structure. Giving the technical route of fatigue life prediction based on the widely used international standards: International Institute of Welding Standard, British Standard and AAR Standard of the Association of American Railway.Secondly, taking a wagon body for coal as an example, the paper made an analysis of static strength and stiffness using I-DEAS software. According to the results of strength analysis, combining with load spectrum tested on line, fatigue life analysis is executed by Fortran language based on IIW and BS Standards. The results show that property choice of weld joint and weld arts can doubly improve fatigue life of structure, for example: weld is grounded or not, weld's orient is line with load or not and so on.Also, the paper deduced reverse solving formula in defined design life based on the three standards. Taking hopper wagon body for grain as an example, using the reverse solving formula, the stress of several typical weld structure in defined design life is obtained. Meanwhile, acuity formula of different fatigue life prediction is given, and the affecting degree of different parameters for life is analysed. Thus, it offered theory foundation for design improvement and product development. |
