Damage detection in a free-free beam structure using reconstructed mode shape data: Numerical approach.

Abstract

The purpose of this work is to localise and magnify the effects of cracks from numerically computed cracked beam mode shapes using reconstructed mode shape data. In general, detecting the presence of a crack solely by observing the vibration mode shape data is difficult. The mode shape data, which contains information about the crack effects present in the beam structure, was obtained in this study using numerical modal analysis. The difference between two sets of detail coefficients computed from the reconstructed mode shape data using the Stationary Wavelet Transform (SWT) clearly indicates the location of the crack in the beam. To improve the resolution of the crack position, the mode shape data is interpolated first using spline interpolation. The comparison of raw data and interpolated data demonstrates a significant improvement in the two sets of detail coefficients from the stationary wavelet transform (SWT). The detailed coefficients from the SWT are extremely useful for resolving the limited number of measurement points encountered during actual modal testing experiments.