Vibration Analysis of Defective Rolling Element

Pure rotating equipment is most commonly found in mechanical systems, which are subjected to unwanted external forces, mainly due to rotor unbalance and shaft misalignment. These forces act to excite the system resulting in unwanted vibrations. Due to these, bearing damages can take place which will pose serious threat to machine life and operation. These bearing damages if not identified and controlled lead to catastrophic failure of bearing in turn failure of system much before the anticipated life. Vibration generally occurs at the machine operating frequency, but sometimes higher harmonics are also excited. The present work is an attempt to investigate the vibration characteristics of rotating mechanical system, which has damaged bearing mounted on overhung shaft. Vibration signals are acquired using accelerometer mounted on one of the bearing housing. The FFT analysis of the acquired data revealed the steady state response of healthy and damaged bearing under operating conditions. Impact hammer testing portrayed the natural frequencies for different overhung length of shaft.