Monitoramento da integridade estrutural a partir de sensoriamento de baixo-custo: investigação de índices de dano e de efeitos de variáveis ambientais

Abstract

Structures are constantly subjected to external inputs, such as the application of forces, wind actions, temperature variations, among others, which can generate wear, noise and failures. Hence, techniques for monitoring the structural integrity are being increasingly applied nowadays. In this methodology, sensors are implemented to measure vibrations and identify changes in vibration parameters generated by these inputs in real time, making it possible to predict and anticipate necessary maintenance, which increases the longevity and safety of systems in general. However, the sensors and data acquisition systems commonly used today demands intensive financial investment. Thus, an instrumentation was performed using a low-cost sensor, of microelectromechanical origin, in a simple structure with 2 degrees of freedom, under the action of vibrations generated by an impact-type input, in order to investigate damage indexes based on natural frequency variations, as well as identifying the influence of environmental variables present. It was simulated damage to the structure through cuts in one of the supporting beams and natural frequency data were extracted for different environmental conditions and different levels of damage. Regarding the effects of environmental variables, a directly proportional relationship between temperature and natural frequencies was found, although almost negligible. Regarding the damage levels, more significant frequency variations were observed as the damage increased. It was found that the implemented acquisition system is suitable to be used for damage detection in structures and that environmental variables can influence the determined natural frequencies. In this sense, the need of measuring environmental variables during the structural monitoring was verified in order to obtain a correct identification of the true state of the system.