This work aims to characterize the dynamical behavior of a multilayered beam with imperfect interfaces thanks to an equivalent model. The imperfect interfaces studied are a result of the coupling conditions of the layers, modelled by a spring and a discontinuity of the displacement. A high stiffness symbolizes a good coupling, conversely, a low stiffness represents a bad coupling between the layers. Such modelling is able to take into account the transition between a perfectly bonded and a fully debonded multilayered structure. This approach has been implemented in an equivalent model used in the current work to characterize experimental samples by an inverse method. The samples used are manufactured to have a decreasing quality of the coupling within the multilayered beam, to compare the behavior of the coupling conditions. The samples are made of glass and epoxy in order to have an overview of the interface quality. The Corrected Force Analysis Technique (CFAT) is used to characterize the samples and check the effect of imperfect interfaces. The characterization is done by estimating the apparent bending stiffness of the sample and the corresponding losses thanks to the measured velocity. The measurements are performed by means of a Laser Doppler Vibrometer (LDV).