The numerical and exprimental simulations of the simultaneous effect of crack and ridge on the natural frequency of the rotating shaft

نوع: Type: thesis

مقطع: Segment: Masters

عنوان: Title: The numerical and exprimental simulations of the simultaneous effect of crack and ridge on the natural frequency of the rotating shaft

ارائه دهنده: Provider: Siamak Azarshab

اساتید راهنما: Supervisors: Dr. Rahman Seifi

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: DR. Amirhossein Mahmoudi & Dr. Mehdi Shaeban

زمان و تاریخ ارائه: Time and date of presentation: 2022/02/23- 10:00-12:00 Am

مکان ارائه: Place of presentation: virtual

چکیده: Abstract: Rotating shafts can have various defects such as mass unbalance, misalignment, cracks, residual shaft bow and etc. In this dissertation, the effect of two cracks and residual shaft bow on the natural frequency of the shaft was investigated experimentally and numerically. First, the effect of crack and residual shaft bow on the natural frequency of the shaft was investigated numerically. to do this, three shafts with a residual bow and two rotating disks that were symmetrically placed on the shaft were considered. the boundary conditions of each of the shafts were similar to the boundary conditions of the rotor Jeffcott. Then the effect of crack and residual shaft bow on its natural frequency was investigated and the results were plotted. It was observed that with increasing crack depth and residual bow value of the shaft, the natural frequency of the shaft decreases. In the next step, the experimental results were examined, for this purpose, three shafts, each of which had residual bow were considered, and cuts were made in each of them with a saw in order to create cracks. The boundary conditions of the shafts were considered as two free ends and the amount of natural frequency was measured by instruments in the laboratory and compared with numerical results. It was observed that the experimental results decreased with increasing the amount of residual shaft bow and increasing the depth of crack of the natural frequency value. The presence of a crack has a greater effect on reducing the natural frequency of the shaft than residual shaft bow. The presence of a crack can reduce the natural frequency by up to 5%, but residual shaft bow can eventually reduce the natural frequency by up to 1%. As a result, the presence of cracks can be detected by natural frequency changes, but for the presence residual shaft bow, it is better to use other properties of the rotor, such as changes in frequency response.

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