Damage detection in a fibre reinforced composite beam using random decrement signatures

The potential application of the random decrement technique for the detection of damage in composite beam type structures is investigated in this paper. Analytical models of composite beams with various levels of delamination were developed, based on the assumed mode method, to obtain the system's response to a random input. An experimental study was conducted to validate the numerical results. Both the theoretical modelling and the experimental study showed that delamination had dissimilar effects on the random decrement signature at different sensing locations, indicating that a large database of random decrement signatures can be used, together with pattern recognition algorithms for the diagnosis of unknown damage. Differences between numerical and experimental results were attributed to the influence of the exciter and non-ideal boundary conditions in the experiments, and the simplistic treatment of structural damping in the models.