Modulation of elastic wave propagation in piezoelectric laminated nanocomposite shells considering agglomeration effects

Due to the unique physical properties, graphene and its derivatives are often used as the reinforcements to improve and modulate mechanical performances and dynamic behaviors of composite materials. In this paper, a semi-analytical finite element method is utilized to analyze the wave properties of functionally graded graphene-reinforced piezoelectric nanocomposite cylindrical shells with graphene agglomeration effects. The effective micromechanics model, the first-order shear deformation shell theory, and the Hamiltonian principle are organically intergrated to derive the wave equation to analyze the modulation of wave propagation of functionally graded graphene-reinforced piezoelectric nanocomposite cylindrical shells by regulating agglomeration effects. The results indicate that the decrease in volume fraction of agglomeration phase and the raising of the amount of graphene sheets in agglomeration phase lead to the reduction of phase and group velocities and hinder the transmission of waves and wave energy. The higher the graphene total volume fraction, the more obvious the influence of the agglomeration effects on the structural wave properties. Meanwhile, it is found that the agglomeration effects can inhibit the modulation of the concentration and functional gradient distribution patterns of graphene on the wave properties. It is noted that the center conversion frequency of out-of-plane modes and the group velocity of the conversion intersection point of out-of-plane modes are sensitive to agglomeration effects, the values of the center conversion frequency and the group velocity of the conversion intersection point increase with the weakening of the agglomeration effects. This work can provide guidance and new thought for the design of smart nanocomposites and the application of elastic wave characteristics in non-destructive testing.