Crack detection in cantilever beam by signature analysis

摘要

In this paper, a novel approach to the crack detection in cantilever beam by vibration signature analysis is established. The crack detection method is based on the vibration analysis under harmonic excitation. An experimental setup is designed in which a cracked cantilever beam is excited by an exciter and the signature is obtained using an accelerometer attached to the beam. To avoid non-linearity, it is assumed that the crack is always open. Natural frequencies obtained from modal analysis as a criterion for crack detection has been extensively used in the last decades due to its simplicity. However the online crack detection and condition monitoring using vibration signature is not straightforward. An efficient technique is necessary to obtain significant results. To identify the crack, contours of the normalized frequency in terms of the normalized crack depth and location are plotted. The intersection of contours with the constant damage index planes is used to relate the crack location and depth. The proposed method is based on the change in natural frequencies extracted from vibration signature of the beam.