Partial-mixed formulation and refined models for the analysis of compositelaminates within an FSDT

The present paper proposes a partial-mixed variational formulation for the analysis of composite laminates within the First-order Shear Deformation Th eory (FSDT). The considered functional is recovered from the Hellinger-Reis sner mixed principle and it appears to be particularly suitable for the det ermination of the FSDT governing equations since the transverse shear stres ses are treated as independent variables. Accordingly, it is possible to ob tain an accurate description of the shear stress profiles. Herein, the atte ntion is concentrated on two different refined FSDT models, both having pie cewise parabolic shear stress profiles. Furthermore, within one of the two refined models, the partial-mixed formulation is used to derive a performin g finite element. Finally, analytical solutions from the classical and the refined FSDT models are compared to three-dimensional (3D) analytical solut ions as well as to results obtained form the proposed laminate finite eleme nt. (C) 1999 Elsevier Science Ltd. All rights reserved.