Analysis of stationary roving mass effect for damage detection in beams using wavelet analysis of mode shapes

Abstract

One of the main challenges in damage detection techniques is sensitivity to damage. During the last years, a large number of papers have used wavelet analysis as a sensitive mathematical tool for identifying changes in mode shapes induced by damage. This paper analyzes the e ect of adding a mass to the structure at di erent positions. Depending on the location and severity of damage, the presence of the mass a ects the natural frequencies and mode shapes in a di erent way. The paper applies a damage detection methodology proposed by the authors, although it has been modi ed in order to consider the addition of the mas. This methodology is based on a wavelet analysis of the di erence of mode shapes of a damaged and a reference state. The singular behavior of a normalized weighted addition of wavelet coe cients is used as an indicator of damage. The presence of damage is detected by combining all the information provided by mode shapes and natural frequencies for di erent positions of the roving mass. A continuous wavelet transform is used to detect the di erence between the response of a healthy state and a damaged one. The paper shows the results obtained for a beam with di erent cracks. The paper analyzes the sensitivity to damage of the proposed methodology by considering some practical issues such as the size of the crack, the number of measuring points and the e ect of experimental noise.