Wavelet-based Inclusion Detection in Cantilever Beams

In this paper, continuous wavelet transform has been applied to inclusion detection in cantilever beams. By means of FEM, a cantilever beam with an inclusion is subjected to an impact on its free end, and its stress wave propagation process is calculated. Here, two kinds of inclusions which are distinct in material behavior have been discussed. And we change the inclusion's sizes in the beam and set it in three different positions to Simulate some complicated situations. For soft inclusion, the results show that the arrival times of incident and reflective wave are distinguishable by performing Gabor wavelet transform and extracting a proper frequency component from the strain data of two certain points on beam edge. Consequently, the position of inclusion is identified and the size of it is investigated quantitatively by the reflection and transmission ratio. For hard inclusion, an improved method is adopted to amplify the signal-to-noise ratio. The inclusion is located by analysis of the difference between an intact beam and a beam with inclusion. In addition, the corresponding dynamic experiments for both kinds of inclusions are carried out to verify the detection method. The experimental results show that Gabor wavelet transform precisely estimates the location and size of inclusions, and is proved to be an effective method to quantify the inhomogeneity in a beam.