Monitoring a delamination in a laminated composite beam using in-situ measurements and parametric identification

A method is described for monitoring a single delamination in a laminated composite plate. The dynamic response of the structure is obtained via the electromechanical impedance of a piezoelectric transducer cemented onto the structure. We focus here on the coupling with bending modes using thin devices which can be embedded in the material during the manufacturing process. A model including the delamination as well as the transducer is presented. The geometrical parameters of the delaminated zone are identified by comparing the modal parameters calculated from impedance measurements with those obtained using our model. Upon applying this method of identification to a test laminated beam, the length and position of several delaminations were estimated to within 15%.