Damage analysis in metal beams by changes in their natural frequencies.

Resumo

Nowadays, the concern with structural damages in the civil construction is in growth,
slender structures, of great dimensions, and old or more economic generate constant concern for the
engineers responsible for its maintenance and stability. In this scenario, considering the growing
demand for structural damage monitoring, this paper presents the results of laboratory tests performed
to indicate the feasibility of a simple signal processing method to identify structural damages. This
method consists of experimental tests using a set of accelerometers that were coupled in two metal
beams to obtain acceleration responses at various levels of structural integrity (cuts in the cross section
of the profile corresponding to 80%, 60% and 40% of the original). The recorded accelerations went
through a simple processing of data for identification of natural frequencies. The numerical modeling
of the beams was also performed in the ANSYS software based on the finite element method, from
which the natural numerical frequencies were extracted. Finally, the experimental natural frequencies
were compared with the numerical ones for the validation of the results. It was possible to identify
damages in the two beams since changes in the natural frequency values were identified at all levels of
section integrity. A good approximation between the experimental and theoretical values was
observed, and in this way, it was concluded that the tests were able to detect structural damage
correctly.