Research On Diagnosis Method Of Fan Blade With Single Crack

Because of its stable air pressure, high efficiency and low noise, fan is extensively applied to factories, mine wells, tunnels, cooling towers, ships and buildings, where it fulfills it role of ventilation, dust removal and cooling, thus providing basic assurance of production safety. As the critical working parts of fan, blades subjected to high centrifugal force and pneumatic load for a long time, which is easy to bring out crack and fracture failure, and even cause major accidents. Therefore, the condition monitoring and fault diagnosis of fan is the most important way to prevent the machine from such incidents. Consequently, the realization of crack fault quantitatively diagnosis to the fan blade working under complex industrial environment both has both important theory significance and application value.In view of this, this paper deduces the mathematical relationship between the crack depth, crack location and the natural frequency of fan blade. On the basis of the blade mathematical model, using the theoretical computed natural frequency as the fault feature, this paper proposes a fast and efficient fan blade crack fault diagnosis method. By means of experimental modal test, the natural frequency of a single crack blade of different failure extent were measured, and the obtained data is analyzed and compared with theoretical calculation method, the proposed diagnostic method are verified, the experiment proved that being the fault feature, natural frequency can be effectively and accurately diagnose the crack location and depth. According to actual working blades, the calculation method of the static and dynamic frequency of blade is deduced, and the actual work condition of fan blade has been simulated with the help of 3D design software and simulation analysis software. The natural frequency calculated by simulation is compared with the value calculated by theoretical method, and the errors between them are small, which consequently provides a simple and feasible method for the sample database establishment of the fan blade crack fault. The main working scope is as follows:(1)Establishing the discrete mathematical model for single crack blade, deducing the relationship between natural frequency and crack depth and location. And then provides a fast and feasible fault diagnosis method for fan blade crack failure.(2)By means of experimental modal test, the natural frequency of a single crack blade of different failure extent were measured, and the obtained data is analyzed and compared with theoretical calculation method, the proposed diagnostic method are verified, the experiment proved that being the fault feature, natural frequency can be effectively and accurately diagnose the crack location and depth.(3)According to actual working blades, the calculation method of the static and dynamic frequency of blade is deduced, which provides a theoretical basis for establishment of the crack fault sample database of fan blade.(4)With the help of 3D design software and simulation analysis software, the fan modal has been established and the actual work condition of fan blade has been simulated. The natural frequency calculated by simulation is compared with the value calculated by theoretical method, and the errors between them are small, which consequently provides a simple and feasible method for the crack fault sample database establishment of fan blade.