An enhanced single damage identification in beams using natural frequency shifts and analytic modal curvatures

Abstract

This article presents an improved procedure for detecting single damage in beam-like structures. Many damage detection methods are based on the analysis of beam natural frequency shifts in damaged and intact states and its analytical modal curvatures. They identify the damage by constructing curves of damage coefficients along the beam and visually determining the point of their mutual intersection. However, for some cases, the absence of an unambiguous point of intersection of these curves or the low accuracy of its localization makes it difficultto use these methods. To accurately determine the mutual intersection of damage coefficient curves, this work proposes to use a subset of modes without one having its curvature close to zero at the site of the alleged damage. This approach greatly simplifies the determination of the point of intersection of the curves of damagecoefficients. An enhanced procedure for the numerical determination of this intersection point is also proposed,rather than the visual one used in existing methods. The effectiveness of the proposed technique was confirmedby numerical simulation followed by experimental verification.