Influence of Helicoidal Crack on Dynamic Behavior of Rotating Shaft

The present study aims at the analysis of vibration characteristics of rotating shaft which contains single helicoidal surface crack. The shaft material is EN8. There are seven shafts out of one is intact shaft other six are helically cracked shafts and of the same material having the same dimensions with a crack orientation of 29, 45 and 55 with the longitudinal axis of rotary. Crack is taken at location 100 mm and 300 mm from bearing side. Crack width is taken as 1 mm and the depth is taken as 1 mm and revolved for 180 of shaft diameter which is taken as a total crack length. Vibration response of each shaft is studied with FFT Analyzer for different rotational speeds along with varying loading condition in which disc is attached to the center of the shaft. The readings from FFT analyzer and the experimental set up are validated by using MSC NASTRAN software. The amplitude of vibrations is increased as rotor weight and shaft speed increased for every angle of orientation of helicoidal crack. The trend of higher amplitude observed for 45crack orientation.