Vibration based damage detection in smart nonuniform thickness laminated composite beams

Laminated composite beams with non-uniform thickness are being used as primary structural elements in a wide range of advanced engineering applications. Tapered composite structures, formed by terminating some of the plies, create geometry and material discontinuities that act as sources for delamination initiation and propagation. Any small damage or delamination in these structures can progress rapidly without any visible external signs. Due to this reason early detection of damage in these systems during their service life is receiving increasing attention. The presence of a crack in a component or structure leads to changes in its global dynamic characteristics results in decreases in the natural frequencies and modifications of the mode shapes of the component or structure. The present work aims to investigate the influences of delamination on the natural frequencies, frequency and voltage responses of smart non-uniform thickness laminated composite beams. In order to guarantee the continuity of curvature at element interfaces, particularly at ply drop-off locations, a higher-order finite element model by considering the electro-mechanical coupling effect is used which can accurately and efficiently represents the dynamic responses of the structure for forced/random stimuli and provide accurate results using fewer elements.