Effect of delamination on the high frequency wave dispersion of composite beams with active piezosensors

One of the most frequently used techniques of structural health monitoring is the usage of piezoelectric materials as actuators or sensors. Piezoelectric wafers provide the ability of monitoring and self-excitation for detecting damage effects on structural vibration and wave propagation. In the area of delamination detection, attention is focused on the excitation and monitoring of symmetric and antisymmetric lamb waves, since they seem to be very promising to reveal the damage existence. The proposed paper will present layerwise mechanics and a finite element capable to describe the response of delaminated composite beams with piezoelectric actuators and sensors. A layerwise beam theory is formulated approximating the through-thickness and in-plane displacements and the electrical field as a continuous assembly of piecewise linear layerwise fields. The theory includes the ability to describe the discontinuities at the delamination region as additional degrees of freedom. The introduction of a variable transverse displacement field provides the capability to capture important antisymmetric Lamb modes at high-frequencies, and also other complex phenomena not captured by models assuming constant transverse displacement fields. Displacements and sensory voltage transient predictions are obtained capturing the high frequency wave propagation in delaminated composite beams. Further analysis of the transient numerical results provides dispersion curves illustrating the effect of the damage introduction on Lamb wave propagation.