Vibration-Based Delamination Detection in Composite Structures Employing Mixed Unified Particle Swarm Optimization

The present paper introduces mixed unified particle swarm optimization (MUPSO) algorithm to detect and quantify the delamination damages in composite beams and plates using vibration responses. MUPSO is a combination of conventional continuous unified particle swarm optimization (UPSO) and a binary version of UPSO, which is proposed in this paper. The first few modes have been used to detect delamination damages through a two-stage method. In the first stage, rough locations of damages have been determined from a mode-shape curvature-based damage index using the gapped smoothing method. In the second stage, the mixed UPSO approach is used to get an accurate lengthwise location of the delamination along with the delamination interface. While the continuous part of the mixed UPSO has been used to obtain the lengthwise location of the damages, the binary part of the mixed UPSO has been used to determine the interface of the damage. The present method has quantified each damage scenario consisting of single and multiple interface delaminations with acceptable accuracy. The algorithm is also found to be performed satisfactorily under a noisy environment. The results obtained from experimental investigation are also presented. Overall, the present two-stage method has shown very good potential in the field of damage detection of composite structures.