Structural health monitoring of a plate excited by ambient load by wavelet transform

Use of environmental loads to perform continuous Structural Health Monitoring (SHM) allows controlling the structural integrity in operative conditions, with considerable timesaving and safety benefits. Aim of this paper is the identification of the damage on a plate excited by potential vortices using the Continuous Wavelet Transform (CWT). The numerical model of the load is based on the relationship between the induced vortex pressure and a rigid wall. The numerical model of the damaged plate is determined by a Finite Element (FE) technique. Eigenvalues and eigenvectors are extracted by the FE solution and they are used to calculate the physical response after by means of the generalized coordinates. An index, based on the analysis of the CWT coefficients, is defined to identify the position of the damage. The proposed index allows detecting the actual damage position with good accuracy and does not require the knowledge of the response of the undamaged plate. In order to study the sensitivity of the index the analysis is performed on a set of different damage amplitudes and positions.