Numerical analysis of a piezoelectric structural health monitoring system for composite flange-skin delamination detection

In this paper, a piezoelectric based Structural Health Monitoring (SHM) system is proposed to detect skin/stiffener debonding and delamination cracks proper of laminated composite structures. The SHM system is analyzed by means of a boundary element code implemented in the framework of piezoelectricity. The multidomain technique, coupled with an interface spring model, is used to model laminated composite structures as well as the bonding between the host delaminated structure and the piezoelectric sensor. Static sensitivity analyses are firstly performed on a drop-ply delaminated structure in order to identify a suitable configuration for the sensor. Then, the dynamic electromechanical response of the damaged structure with the bonded piezoelectric sensor is investigated. The definition of a damage index allows an effective identification of the skin/stiffener debonding occurrence. In order to fully characterize the host structure SHM system assembly, the fracture mechanics behavior of the structure is also studied in terms of the total energy release rate G and of the phase angle Ψ.