On refined computational models of composite laminates

Abstract

SUMMARYFinite element models of the continuumsbased theories and two-dimensional plate/shell theories used in the analysis of composite laminates are reviewed. The classical and shear deformation theories up to the thirdorder are presented in a single theory. Results of linear and non-linear bending, natural vibration and stability of composite laminates are presented for various boundary.conditbns and lamination schemes. Computational modelling issues related to composite laminates, such as locking, symmetry considerations, boundary conditions, and geometric non-linearity effects on displacements, buckling loads and frequencies are discussed. It is shown that the use of quarter plate models can introduce significant errors into the solution of certain laminates, the non-linear effects are important even at small ratio of the transverse deflection to the thickness of antisymmetric laminates with pinned edges, and that the conventional eigenvalue approach for the determination of buckling loads of composite laminates can be overly conservative. I . INTRODUCTIONIncreased utilization of composite materials in a variety of structures, including space and underwater vehicles, autotnotive parts, electronic and medicai devices, and sports equipment, has led to increased research activity in the mechanical characterization, structural modelling, and failure and damage assessment of composite materials. While composite materials offer many desirable structural properties over conventional materials, they also present challenging technical problems in the understanding of their structural behaviour, manufacturing, and in the damage and failure modes developed during their service:The subject of composite materials is an interdisciplinary area where chemists, materials scientists, chemical 'engineers, mechanical engineers, structural engineers and manufacturing engineers contribute to the overall product. From computational mechanics considerations, the study of composite materials involves modelling of fabrication processes (heat and mass transfer, and fluid flow) and structural response including micromechanics aspects, inelasticity and damage.Laminated composites consist of two or more different composite materials that are bonded together to achieve the best properties of the constituent layers. Most composite laminates are made of layers of the same orthotropic material, with the material co-ordinates of each layer oriented differently with respect to the laniinate co-ordinates.

Shear deformation effect in non-linear analysis of composite beams of variable cross section

“…Previous formulations concerning composite beams of thin walled cross sections or laminated cross-sections are analyzing these beams using the 'refined models'. However, these models do not satisfy the continuity conditions of transverse shear stress at layer interfaces and assume that the transverse shear stress along the thickness coordinate remains constant, leading to the fact that kinematic or static assumptions cannot be always valid [18][19][20].…”

Effective modelling of structural glass with laminated shell elements

“…Considerable research efforts have been devoted to the establishment of plate theory-based lamination models for a close estimation of the structural behaviour at reduced computational demands. Layer-wise models (LWMs) pioneered by Reddy and coworkers [8][9][10] achieve the reproduction of piecewise continuous displacement fields in the thickness direction by employing first-order shear deformation theory (FSDT) or higher-order shear deformation theories (HSDTs) at each constitutive layer. On the other hand, equivalent single layer models (ESLMs) [11][12][13][14][15][16] obtain piecewise displacements by simply adding…”

Nonlinear analysis of laminated shells with alternating stiff/soft lay-up

“…An enormous amount of research effort has therefore been made in the establishment of plate theory-based lamination models for a close estimation of the structural behaviour at reduced computational demands. Layer-wise models (LWMs) [1][2][3][4] and zigzag models (ZZMs) [5][6][7][8][9] achieve the reproduction of piecewise continuous displacement fields in the thickness direction by employing the first-order shear deformation theory (FSDT) or higher-order shear deformation theories (HSDTs) at each constitutive layer and imposing C 0 continuity constraints at laminar interfaces. The Equivalent Single Layer Models (ESLMs) [10], which follow the idea of Murakami [11] with further developments, obtain piecewise displacements by simply adding Murakami's zigzag function [11] to a classical Taylor type expansion defined along the whole plate thickness.…”