Abstract The present study develops and applies a neuro-fuzzy modal vibration control of smart laminated composite structures with piezoelectric layers via Mixed theory. Differently from previous studies, the composite structures in this paper are modeled via the Mixed Theory using the High-order Shear Deformation Theory (HSDT) theory. The Mixed Theory adopts a single layer when representing the mechanical displacement field, through HSDT theory, and multiple layers (Layerwise theory) for the electrical degrees of freedom. The Mixed Theory is computationally implemented in the Matlab® software using a plate-type element called Serendipity. Moreover, a neuro-fuzzy active vibration controller is implemented to attenuate the vibration of the smart composite structures. The numerical results validate the electric-mechanical coupling adopted, showing the importance of the mixed theory in the static and dynamic modeling of slender beams and plates with piezoelectric layers. Finally, the results of the robustness analysis indicate that the neuro-fuzzy controller has benefits compared with the linear quadratic regulator.

ABSTRACT: In this paper it was sought to enhance the potential damage detection, location and quantification of the Discrete and Continuous Wavelet Transforms in thin damaged laminated composite plates by a signal derived from vibration modes. To evaluate the ability of both transforms in the damage prognostic it was also proposed the use of Damage Indexes. The matrix damage level occurs during the impulsive load application over the analyzed structures. The finite element used was a Serendipity-type with rectangular shape, 8 nodes and 5 mechanical degrees-of-freedom per node, which was formulated by First-order Shear Deformation Theory on MATLAB (MathWorks®). The dynamic equation of motion including internal damage was solved by the Newmark implicit integration method. The results have demonstrated that mother wavelets, whether discrete or continuous, applied in dynamic signal processing, can detect a small damage magnitude in the matrix level. Moreover, the proposed Damage Indexes can quantify the damage magnitude as well as determine the most appropriate vibration mode and scalar parameter of the Continuous Wavelet Transform for damage detention.

ABSTRACT: This paper proposes an active vibration control technique, which is based on linear matrix inequalities, that is applied to a piezoelectric actuator bonded to a composite structure, forming a so-called smart composite structure. Serendipity-type finite element, based on first-order shear deformation theory with rectangular shape, eight nodes, five mechanical degrees of freedom (DOF) per node and eight electrical DOF per piezoelectric layer, is established for the composite structural model. Additionally, a mixed theory that uses a single equivalent layer for the discretization of the mechanical displacement field and a layerwise representation of the electrical field is adopted. Temperature effects are neglected. Simulation results illustrate the effectiveness of the proposed vibration control methodology for composite structures.