Parametric Modeling of Composite Laminates (original) (raw)
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On refined computational models of composite laminates
International Journal for Numerical Methods in Engineering, 1989
Finite 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. INTRODUCTION Increased 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 coordinates of each layer oriented differently with respect to the laniinate coordinates .
Reduced Order Modeling of Composite Laminates Through Solid-Shell Coupling
Journal of Aerospace Technology and Management, 2017
Composite laminates display a complex mechanical behavior due to their microstructure, with a through-thickness variation of the displacement and stress fields that depends on the fiber orientation in each layer. Aiming to develop reduced-order numerical models mimicking the real response of composite structures, we investigated the capability and accuracy of finite element analyses coupling layered shell and solid kinematics. This study represents the first step of a work with the goal of accurately matching stress evolution in regions close to possible impact locations, where delamination is expected to take place, with reduced computational costs. Close to such locations, a 3-D modeling is adopted, whereas in the remainder of the structure, a less computationally demanding shell modeling is chosen. To test the coupled approach, results of numerical simulations are presented for a quasi-statically loaded cross-ply orthotropic plate, either simply supported or fully clamped along its boundary.
1995
The objective of the present study is the computational and analytical modelling of a stress and strain state of the composite laminated structures. The exact three dimensional solution is derived for laminated anisotropic thick cylinders with both constant and variable material properties through the thickness of a layer. The governing differential equations are derived in a such form that to satisfy the stress functions and are given for layered cylindrical shell with open ends. The solution then extended to the laminated cylindrical shells with closed ends, that is to pressure vessels. Based on the accurate three-dimensional stress analysis an approach for the optimal design of the thick pressure vessels is formulated. Cylindrical pressure vessels are optimised taking the fibre angle as a design variable to maximise the burst pressure. The effect of the axial force on the optimal design is investigated. Numerical results are given for both single and laminated (up to five layers) cylindrical shells. The maximum burst pressure is computed using the three-dimensional interactive Tsai-: Wu failure criterion, which takes into account the influence of all stress components to the failure. Design optimisation of multilayered composite pressure vessels are based on the use of robust multidimensional methods which give fast convergence. Transverse shear and normal deformation higher-order theory for the solution of dynamic problems of laminated plates and shells is studied. The theory developed is based on the kinematic hypotheses which are derived using iterative technique. Dynamic effects, such as forces of inertia and the direct influence of external loading on the stress and strain components are included at the initial stage of derivation where kinematic hypotheses are formulated. The proposed theory and solution methods provide a basis for theoretical and applied studies in the field of dynamics and statics of the laminated shells, plates and their systems, particularly for investigation of dynamic processes related to the highest vibration forms and wave propagation, for optimal design etc. Geometrically nonlinear higher-order theory of laminated plates and shells with shear and normal deformation is derived. The theory takes into account both transverse shear and normal deformations. The number of numerical results are obtained based on the nonlinear theory developed. The results illustrate importance of the influence of geometrical nonlinearity, especially, at high levels of loading and in case when the laminae exhibit significant differences in their elastic properties. Cylindrical coordinates Moduli of elasticity Poisson's ratios Shear moduli Normal stresses Shear stresses Strain components Displacements Components of body forces per unit of volume Elastic constants Angle of the fibre orientation Coefficients of the deformation Stress functions N umber of layers Layer number Uniformly distributed load (pressure) Axial force Constant of integration Material strengths • Stress components in the material coordinate system Critical load IV
A Finite Element Formulation of Multi-Layered Shells for the Analysis of Laminated Composites
This paper presents a multi-layered/multi-director and shear-deformable finite element formulation of shells for the analysis of composite laminates. The displacement field is assumed continuous across the finite element layers through the composite thickness. The rotation field is, however, layer-wise continuous and is assumed discontinuous across these layers. This kinematic hypothesis results in independent shear deformation of the director associated with each individual layer and thus allows the warping of the composite crosssection. The resulting strain field is discontinuous across the different material sets, thereby creating the provision that the inter-laminar transverse stresses computed from the constitutive equations can be continuous. Numerical results are presented to show the performance of the method.
A geometrically exact formulation of thin laminated composite shells
Composite Structures, 2017
A geometrically exact approach is employed to formulate the equations of motion of thin multi-layered composite shells subject to excitations that cause large strains, displacements, and rotations. Ad hoc truncated kinematic approximations of the obtained semi-intrinsic theory delivers, as a by-product, the kinematics of the Koiter and the Naghdi theories of shells, respectively. Numerical simulations are carried out both for cylindrical and spherical shells: nonlinear equilibrium paths are constructed considering a quasi-static load increase. The comparisons between the results furnished by the geometrically exact theory and those obtained by Koiter and Naghdi theories show the high accuracy of the proposed nonlinear approach. Classical theories become increasingly inaccurate at deflection amplitudes of the order of the shell thickness, evidencing that significant misrepresentations of the system behavior are possible if reduced-order kinematics are taken into account.
A review of research and recent trends in analysis of composite plates
Sādhanā, 2018
The use of advance composite materials is increasing in various industrial applications such as renewable energy, transportation, medical devices, etc. As the demand for stability under high mechanical, thermal, electrical and combined loads is increasing, research is being focused on developing newer types of composites and developing analytical and numerical methods to study composite plates as well. The present work is aimed to provide a comprehensive review of research in the structural analysis of composite plates along-with research trends in the last 15 years. The article first presents the evolution of plate theories comparing their formulations, applicability and discusses some key papers, results and conclusions. Evolution of research from the equivalent shear deformation theories (ESL) such as first order theory and higher order theories based on various shape strain functions e.g., polynomial, trigonometric to layer-wise, zigzag and displacement potential theories is presented. The comparative analysis of various solution approaches is done based on a review of research work in the structural analysis of plates. This is followed by review of meshless analysis methods for composite materials highlighting problem domains where conventional finite element analysis (FEA) approach has limitations. This article also presents a discussion on the new methods of plate analysis such as region-by-region modeling, hierarchic modeling and mixed FE and neural network based modeling. An attempt has been done in this article to focus on research trends in the last 15 years.