High-frequency Dispersion Characteristics of Smart Delaminated Composite Beams

Many promising techniques for structural health monitoring rely on the usage of in situ piezoelectric actuators and sensors, which provide the ability of self-excitation and monitoring of the damage effect on the structural vibration and wave propagation. This article presents layerwise mechanics and a finite element capable of describing the response of delaminated composite beams with piezoelectric actuators and sensors. The layerwise beam theory approximates the through-thickness, in-plane displacements, and electrical field as a continuous assembly of piecewise linear layerwise fields through the thickness. This theory further describes the field discontinuities across the delamination as additional degrees of freedom. The introduction of a variable transverse displacement field provides the capability to capture important symmetric and antisymmetric high-frequency modes, guided waves, and other complex phenomena. Pseudo Wigner-Ville distributions provide the frequency dispersion characteristics of predicted and measured time responses of beams with single delaminations and an active piezoelectric sensor pair. Time—frequency plots obtained from the experimental and numerical data are correlated and their ability to reveal the presence and size of delamination is investigated.