Applications of bispectrum analysis to inspection of fatigue damage in quay cranes

Abstract

The quay crane is a special mechanical equipment which can lift the container vertically and horizontally through intermittent circulation movement. Fatigue crack is one of the main kinds of damage in quay cranes. The generation and development of fatigue crack are invisible, which makes the identification of fatigue cracks a great challenge. From the dynamic point of view, fatigue cracks have nonlinear dynamic characteristics beyond the linear dynamic category. The traditional damage detection methods based on linear hypothesis are difficult to effectively recognize the nonlinear dynamic characteristics of fatigue cracks, so they cannot be effectively used for structural fatigue crack detection. In order to overcome the limitations of the existing linear damage detection methods, bispectrum analysis, a nonlinear dynamic analysis method, is introduced in this thesis. By drawing on the use of bispectrum analysis to describe the nonlinear dynamic characteristics of rotating structures, a fatigue crack detection method based on nonlinear dynamic characteristics of quay cranes is developed.