Analysis of Piezoelectric Composite Beams and Plates with Multiple Delaminations

In the present work, the effect of delamination or debonding on the static and dynamic characteristics of laminated piezoelectric beams and plates is studied. A four-noded quadrilateral shear flexible plate element is developed to model the damages in composite substrate and in piezoelectric layers. The elastic stiffness and electro-elastic stiffness degradations are introduced at the elemental level through coupled constitutive relations. The undamaged structure is modeled as a single laminate while the delaminated region is modeled as sublaminates whose interface contains the desired delamination or debonding. The continuity of displacement is maintained across the delaminated edge by imposing the strain-based multipoint constraints. Numerical studies are conducted on composite specimens with surface bonded active layers. The results are presented to evaluate the performance of these smart structures in the presence of delamination. For actuators, the performance is measured in terms of the achievable deflection control and in sensors as a measurable output voltage. It is observed that actuator and sensor debonding degrade the capabilities of active materials significantly. Therefore, the study concludes that a damage tolerant approach is essential for the design of smart structural systems to account for damage-induced uncertainty in the functional properties of smart actuators and sensors.