Changes of Natural Frequencies of Shafts Due to Pitting Corrosion

Pitting corrosion is a typical damage on structures, which causes stiffness reduction and mass loss. These changes affect the vibrational behavior of corroded structures. In this study, a three-dimensional finite element model is used to investigate the influence of pitting on the natural frequencies of transverse vibration of a clamped-free shaft. The results of the finite element numerical simulation are validated by experimental results and the beams analytical methods. The simulation results show that the increase in the amount of corrosion reduces the natural frequencies, but the trend of this change differs for different modes. In addition, the percentage change in the natural frequencies because of the increase in the length of the corroded region and the change of its location depends on the mode shapes. The results also indicate that the corroded surface is effective in the amount of change of transverse natural frequencies of the shaft.