Avaliação numérica do método das diferenças nas curvaturas modais na detecção de danos em vigas

Abstract

The structures, during it’s lifetime are subject to actions which can bring on damages as natural deterioration, corrosion and fatigue of the materials used. Damages not detected in early stages can lead to fails, committing the structure’s integrity and safety. The monitoring and analysis of possible damages can be performed by techniques that do not change yours properties, named Non Destructive Evaluation (NDE). Among several NDE techniques, the dynamic tests have received great attention in civil engineering from the potential of identify damages in early stages as from the measurement of structure's dynamics characteristics before and after the damage. This work had as aims to evaluate numerically, by Finite Element Method, the application of the Changes in Curvature Mode Shapes method for damage detection in beams and determine the minimal number of mode shapes to identify the damages. In the numerical modeling was used the Calculix software, wherewith there was obtained eight bending mode shapes. The changes in the modals curvatures were determined of approximate manner by finite differences. The damage’s identification was obtained by the comparison between the changes in the modal curvatures of the intact beam with the damaged beams. The method proved to be efficient identifying in all cases the modeled defects. And was conclued that the application of the method to the detection of damages in beams require at least three mode shapes to locate with good precision the damage position.