Natural Frequency Response of Rotor Shaft to Crack Depth and Crack Location

Rotating components of various machines as turbine, pumps, generators and compressor may fail due to crack generation and propagation. Rotor shaft is considered as one of the important part of various rotating machines. Due to manufacturing defect or cyclic loading, fatigue crack may appear in rotating shaft. Crack is considered as one of the main reasons for catastrophic failures in rotating shaft. The diagnosis of shaft faults has been gaining importance in recent years. To examine the vibration characteristics of cracked shaft, a steel shaft supported by two bearings was used. The shaft models with various crack locations and crack depth were designed in CATIA. Different crack depths 0.16, 0.33, 0.5, 0.66, 0.83 & 1 percent of maximum crack depth were provided to shaft model. Crack locations altered 75, 150, 225, 300, 375, 450 mm from bearing support. Modal analysis of these shaft models carried out using ANSYS. Natural frequencies obtained from modal analysis were analysed. Natural frequencies obtained from modal analysis were validated with whirling of shaft experimental set up.