AVE2016 – 5ème COLLOQUE FRANCOPHONE ANALYSE VIBRATOIRE-Novembre 2016

Wavelet modal analysis for damage location in structures

Roger Serra

INSA Centre Val de Loire, Laboratoire de Mécanique et Rhéologie, 3 rue de la Chocolaterie, 41000 Blois, France

Lautaro Lopez

Universidad Nacional de Rosario (UNR), Facultad de Ciencias Exactas y Agrimensura, Rosario, Argentina

INSA Centre Val de Loire, Laboratoire de Mécanique et Rhéologie, 3 rue de la Chocolaterie, 41000 Blois, France

Damages such as cracks and pores are inevitable in mechanical and civil engineering structures during their service life. To ensure the structural integrity and prevent it from sudden collapses, structure health monitoring (SHM) are required.

Damage detection methods based on the dynamic measurements of structures are one of the most important techniques for damage evaluation. It is based on the fact that the loss of stiffness due to damage affects the dynamic response of the structure, this being mainly modal parameters such as natural frequencies, modal shapes, etc.

This study presents the use of wavelet analysis to locate damage from changes in modal parameters in a beam. Wavelet transform is mainly attractive because of its ability to treat noisy signals and detect any local singular behavior of a signal. Perturbations in modal shapes due to damage, which are invisible, will be amplified though a wavelet transform so that a detection of crack location becomes possible practically.

 Results will be contrasted with classical indicators that use natural frequencies, mode shapes, mode shapes curvatures or stored strain energy, for example, to assess damage.

An experimental part, consisting of a clamped-free beam with equally-spaced accelerometers on its surface, is going to prove the proposed method. Since numerical and experimental part were in agreement, it is possible to say that Modal Wavelet Analysis is a good damage indicator and could be used in practice.