A HYBRID ASSUMED-STRAIN FE MODEL FOR THE ANALYSIS OF COMPOSITE LAMINATES

CAZZANI, ANTONIO MARIA;TRALLI A.;GARUSI E.

2004-01-01

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Abstract

A finite element model for the analysis of symmetric laminates is presented: it is based on a hybrid formulation where the displacement and the strain fields are independently modeled, within the framework of FSDT and in the hypothesis of perfect bonding between the layers. An in-plane strain field is defined for the composite as a function of some parameters, whose number is however independent of the number of layers making up the plate: once this strain field is defined, in-plane stresses for each lamina can be evaluated via constitutive law, while transverse shear stresses are computed layer-wise by direct integration of the equilibrium equations, account taken of the continuity requirements and of the boundary conditions. The model allows for an accurate evaluation of the interlaminar stresses and shear-locking phenomena are completely avoided; the finite element model is consistently deduced by a modified Hu-Washizu type variational principle, and the corresponding element stiffness matrix is developed. Some meaningful benchmark problems are finally presented, in order to assess the performances of the proposed laminate element.