Generalised local entropy analysis for crack detection in beam-like structures

Generally, cracks would lead in local discontinuity and sudden change in mode shape, and the local entropy of beam mode will change with the discontinuity of mode shape. Based on this property, cracks can be detected without using a healthy mode shape serving as the baseline. This paper presents a generalised local entropy (GLE) analysis method for crack detection in beam structures, which is a non-baseline mode shape-based damage detection algorithm for beam-type structures. The fundamental and the second-order vibration modes of a cracked cantilever beam are analysed with the presented method. The proposed prediction scheme is validated by simulations and experiments. Based on the results obtained in this paper and the qualities of simplicity and efficiency of GLE method, a mode shape-based crack identification approach is developed as an alternative damage index for structural health monitoring and non-destructive testing.