| MW grade fan blade wheel hub is contested blade and principal axis through the bolt, its force is complex, and extremely easy stress concentration phenomenon happens. The work environment of fan are the plateau,the gobi and sea, therefore there are some more difficult for the maintenance of fan hub. For, the influence of the force size and wind direction of the fan hub on the wheel hub, its work stress is under yield strength, and its work safety requirementsis long for 15 to 20 years. Therefore, for the safety of the MW level fan wheel hub, ductile iron of fan wheel hub is studied with the high cycle fatigue test. Through the force analysis of the wheel hub, it is found that the wheel hub, in working process, is mainly affected by the tensile stress and reverse force, etc.In order to understand whether the fan wheel ductile iron QT350-22 LT is content to the fatigue property of fan or not, high cycle fatigue experiments of QT350-22 LT are tested in this paper. According to the fracture mechanism, numerical simulation is made by the fatigue limit before get.MW grade fan wheel ductile iron and push weeks-the fatigue test are mainly studied in this paper, and the S-N curve is drawn, through the S-N curve it is indicated that the fatigue life in different stresses,it,s high cycle fatigue life is 250MPa. And then, analyzes the morphology of the high cycle fatigue fracture surface is analyzed. There are obvious fatigue propagation source area, crack area and transient breaking area in high cycle fatigue fracture. Contrasting the fractures of the high cycle fatigue, tensile, impact at room impact at low temperature and low cycle fatigue of MW fan wheel ball, their similarities and differences are analyzed. Through contrasting the picture, we find that the high cycle fatigue fracture surface is prototypes brittle fracture.In addition, the fatigue limit before get as reference, the strength of the material for the standard, respectively stress and reverse force are put pressure on the flange. Through numerical simulation, it is obtained that the largest position of the stress is flange; single point of maximum stress is 156MPa; the conclusion is consistent to the actual work. Trough the Goodman-Smith fatigue curve, safety coefficient of fan hub is 1.73. And stress concentration is not more than fatigue limit of material. It is proved that QT350-22 LT fan hub ductile iron can satisfy the design requirement of stress. |
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