Continuous wavelet transform for structural health monitoring of a pipe

In this paper, a Structural Health Monitoring (SHM) procedure, based on the Continuous Wavelet Transform (CWT) applied on a pipe excited by a flow that carries a travelling load, is presented. The proposed procedure allows the early stage localization of damages along the structure. The basic idea is to take advantage of time-space relation given by a traveling load of which speed is known, because wavelet analysis may highlight the singularities of a signal related with the damage. The displacement of the pipe excited by the traveling load shows singularities when the load crosses the damages, because the elastic waves are reflected in correspondence of the structure discontinuity. An index, based on the analysis of the CWT coefficients, is defined to identify these singularities in time and the load velocity law allows finding their correspondent position. A numerical test is performed to validate the performance of the proposed technique.