EVALUATION OF NUMERICAL AND EXPERIMENTAL TECHNIQUES FOR DAMAGE DETECTION

Structural systems are usually subjected to degradation processes due to a combination of causes, such as: design or constructive problems, unexpected loading or a natural process of degradation due to the structures ageing. The effects of that dete- rioration results in damaged regions whose main characteristics are localized stiffness decreases of the structure. A common procedure presented in several papers on damage detection to evaluate those localized damages is done using measured vibrational data of the structure as nat- ural frequencies and vibration modes in damaged and/or undamaged states of the struc- ture. Firstly, the present study analyzes the sensibility of the structural vibration charac- teristics as a function of geometrical and quantitative damage variations. Such analysis is done through experimental tests of controlled damages in a cantilever beam. The effects of the localization and magnitude of damages on the structural natural frequencies vari- ation is then estimated and a profile of the sensibility of the vibration data is developed. Secondly, the efficiency of a damage detection technique based on the strain energy deviation between damaged and undamaged structural vibration modes is evaluated by means of the experimental tests. Finally, to circumvent the case of reduced set of experimental data, the applied dam- age detection technique is evaluated through a proposed methodology of damage identi- fication with incomplete modal data.