96. A common cause of the Babbitt linings cracking in a turbine journal bearing is from ________.

Rotor vibration causes fatigue and cracking in Babbitt linings due to repeated flexing and stress. Babbitt is designed for smooth oil film support, not vibration absorption. Excessive vibration, from unbalance or misalignment, creates cyclic loading that leads to fatigue cracks. Therefore, vibration generated by the rotor is the common cause of Babbitt cracking in turbine journal bearings.