NONLINEAR VIBRO-ACOUSTIC ANALYSIS OF COMPOSITE PLATES WITH EMBEDDED DELAMINATIONS

This paper concerns the development of a numerical model to analyse the transient vibration and sound radiation of composite laminated plates with existing zones of delaminations and subjected to time-varying loadings. The structural model of a delaminated composite plate is derived using a modified variational method based on the three-dimensional theory of elasticity, and the nonlinear kinematic contact conditions between the surfaces of adjacent delaminated layers are considered in the theoretical modelling. The time-domain boundary integral equation is used to determine the resulting acoustic field of the plate. The instability problem related to the boundary integral formulation is overcome by reformulating the integral equation to a Burton-Miller type equation. The results show that both the structural and acoustic responses of a composite laminated plate are affected by the presence of a delamination. When a delaminated composite plate is under a harmonic excitation with hybrid frequencies, the vibration and acoustic responses of the plate consist not only the fundamental excitation frequencies and but also the super-harmonic components and combination harmonics of the excitation frequencies.