In this paper, An-Non destructive test procedure was used to study the effect
of depth and Location of circumferential cracks on the vibration characteristics
of the rotating shafts. The first procedure was to measure the natural
frequencies of rotating shaft before renewing circumferential cracks with
different dimensions and depths from the bearing of the rotating shaft using
(vibration analyzer B & K type 2515) apparatus to analyze the vibrational
characteristics during the rotation and comparing it with mathematical analysis
using the method of mounting the rotating shaft. Secondly, a crack of certain
depth and dimension away from the rotating shaft bearing was made. The
measurements of the natural free vibration due to the presence of the crack
were carried out. The study took into consideration the diameter and the length
of the rotating shaft, beside the measurement of the natural free vibration of the
shaft. The practical results showed a decrease in the natural frequencies of
rotating shaft when the crack prested. This decrease was more when the crack
located in areas near the bearing than was located away from the bearing.
Key Word : Shaft, Crack, Circumferential, Frequency, Depth.