Damage characterization of delamination in smart composite laminates based on smooth transition of displacement field

A dynamic analysis method has been developed to investigate and characterize the effect due to the presence of discrete single and multiple delaminations of composite laminated structures. The Fermi-Dirac distribution function is combined with an improved layerwise laminate theory to model a smooth transition in the displacement and the strain fields of the delaminated interfaces. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Based on the developed model, the effects of discrete delaminations are quantified by comparing transient responses of composite plates and piezoelectric sensor outputs.