Improved finite element viscoelastic analysis of laminated structures via the enhanced first-order shear deformation theory

In this paper, a new finite element formulation based on the enhanced first-order shear deformation theory (EFSDT) is developed for the efficient and accurate viscoelastic analysis of multilayered composite and sandwich plates. The main objective herein is to systematically establish the relationship between two independent theories (i.e., third order zigzag model and conventional FSDT) in the Laplace domain via the strain energy transformation. For viscoelastic problems, the complexity of dealing with viscoelastic materials can be simplified by introducing the concept of Laplace transform. Based on the predefined relationship, the proposed finite element model has the same computational advantage as that of the conventional FSDT (5-DOFs), while allowing the improved local layer-wise distributions of viscoelastic responses via the recovery procedure. In the model, a simple eight-noded isoparametric plate element is employed to analyze the viscoelastic response of multilayered composite and sandwich plates. Furthermore, for the isotropic material, a reference solution based on the three-dimensional finite element model is newly introduced to evaluate the accuracy of the viscoelastic behavior. To demonstrate the perforance of the proposed finite element model, the results obtained are compared to those of the conventional FSDT and three-dimensional finite elements with commercial software (i.e., ABAQUS).