Micromechanics-based structural analysis of thick laminated composites (original) (raw)
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50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009
Initial development of a multiscale progressive damage and failure analysis tool for laminated composite structures is presented. The method models microdamage at the lamina level with the thermodynamically based Schapery Theory. Transverse cracking and ber breakage, considered failure mechanisms in this work, are modeled with failure criteria evaluate at the micro-constituent level using the Generalized Method of Cells.
Micro Mechanical Modeling of Fiber / Epoxy Unidirectional Laminates Using Fea
The focus of the study was to develop the micromechanical model associated with proper damage model to predict the overall mechanical behavior of fiber/matrix unidirectional laminates. The present and first investigation studies the influence of fiber-matrix interface on the behaviour of fiber reinforced composite lamina using micromechanical models. Mechanical properties E1 and E2 are determined at various volume fractions. The second investigation studies the micro-thermo elastic behaviour of the square unit cell of a hybrid fiber reinforced composite lamina. Later this model is extended to predict the coefficients of thermal expansion of graphite-boron hybrid fiber reinforced lamina for various volume fractions.In the third investigation, an analytical solution of the thermal stresses for a fiber embedded in a matrix is presented based on the idea of the finite element and under some simplifying assumptions. The analytical solution to the problem is found for the case when the length of the embedded bar (fiber) is much greater than its radius, and the Young's modulus of the matrix is much less than that of the fiber. The problem is also solved numerically by means of finite element analysis using ANSYS 10.0. Both results are compared and it is shown that both approaches coincide very close qualitatively and quantitatively although significant discrepancies may appear at specific points for specific cases. For all above three cases 3-D finite element models have been developed from the representative volume elements of the composite which are in the form of square unit cells. The finite element software ANSYS 10.0 has been successfully executed to evaluate the properties.
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 .
Journal of Composite Materials
This paper presents a micromechanics-based 3D finite element model for predicting the damage initiation, propagation, and failure strength of TC33/Epoxy carbon fiber reinforced polymer (CFRP) unidirectional lamina under biaxial loadings. The finite element model is generated by introducing representative volume element (RVE) with a random distribution of fibers and a non-zero thickness, numerically identified interface phase via cohesive elements. In the finite element model, the carbon fibers are considered as elastic, while the elasto-plastic behavior and damage of the matrix are governed by extended Drucker–Prager plastic yielding model and ductile damage criterion. By imposing periodic boundary conditions to the RVEs, various cases subjected to uniaxial and biaxial loading conditions are carried out. During the combined transverse and in-plane shear stress states, a failure transition from compression- or tension-dominated to shear-dominated is captured, and the effects of the i...
Multi Scale Modeling and Failure Analysis of Laminated Composites
journal of applied mechanical engineering, 2016
Citation: Uniyal P, Gunwant D, Misra A (2016) Multi Scale Modeling and Failure Analysis of Laminated Composites. J Appl Mech Eng 5: 229. Abstract In present study a multi scale modeling and failure analysis of laminated composites is performed. for micro level study Rule of Mixtures and Halphin-Tsai equations are used to determine lamina properties. Off-axis failure strength of lamina for different volume fractions are calculated using Finite Element software ANSYS. Finite element analysis results are compared with analytical results and published experimental results. In macro level study of laminates first ply failure load of laminates is calculated using ANSYS and compared with analytical results. Various failure theories i.e. maximum stress theory, maximum strain theory, Tsai-Wu, Tsai-Hill and Puck failure criteria are implemented. First ply failure load for different lamination schemes are calculated for uni-axial and Bi-axial loading conditions.
Micro–Macro Analysis of Composite Laminates for the Prediction of Damage Initiation and Propagation
A robust scheme for damage prediction in multi-layered fiber-reinforced composite laminates using finite element analysis of a partially homogenized macro-model has been developed. It is intended to capture the initiation and propagation of matrix damage at the microscopic scale using actual scale macrostructure in the critical zones of interest. The "zones of interest" in the macrostructure such as points of stress concentration, cracks etc., could potentially be modeled as an array of fibers perfectly bonded to the matrix material, while maintaining the volume fraction same as that of the composite lamina. The rest of the macrostructure has been homogeneously modeled using the classical constitutive relations. The locality principle validates the scheme of partial homogenization. The damage evolution has been observed in [0/90] laminate by plotting global stress strain response. The estimated results are in very good agreement with the experimental results.
Composites Science and Technology, 2007
An effective integration of a three-dimensional (3D) micromechanical and finite element (FE) modeling framework is proposed for the analysis of thick-section fiber reinforced plastic (FRP) composite materials and structures. The proposed modeling framework is applied to a pultruded composite system. It consists of two alternating layers with unidirectional fiber (roving) and continuous filaments mat (CFM) reinforcements. Nonlinear 3D micromechanical models representing the different composite layers are used to generate through-thickness composite's effective responses. Approximate traction continuity and strain compatibility relations in the micromechanical models are expressed in terms of the average stresses and strains of the sub-cells that recognize the fiber and matrix responses. The nonlinear elastic behavior is attributed only to the matrix sub-cells. The nested nonlinear micromechanical models are implemented at each integration (Gaussian) point in the FE structural analyses. A linearized structural response will produce a trial strain increment for each Gaussian integration point and an iterative solution is performed until a structural-level convergence criterion is met. At every iteration, the micromechanical models are called to provide effective material responses. An efficient numerical implementation of the micromodels is required in order to achieve accurate solutions and accelerate the structural-level convergence. Thus, stress correction algorithm is performed in each level of the nested micromodels. Axial tension and compression tests on off-axis E-glass/vinylester coupons and notched specimens are used to calibrate the in situ material properties of the fiber and matrix and verify the prediction ability of the nested micromodels. The nonlinear calibration of the matrix is done by using the overall axial shear stress-strain response generated from Iosipescu (V-notched) specimens. Good agreement is shown for all off-axis angles when comparing the experimental stress-strain curves with those predicted by the analyses with the proposed micromodels.
A Computational Damage Micromodel of Laminated Composites
International Journal of Fracture, 2006
A new computational damage micromodel for laminates, which takes into account classical experimental micro- and macro-observations for various stacking sequences, is described. The first computational examples are shown.
Homogenization Method to Calculate the Stiffness Matrix of Laminated Composites
Eng
New analytical models have been developed for predicting equivalent Young’s and shear moduli of laminate composites. Sets of procedures and calculations are presented in order to obtain equivalent properties in all levels, lamina and laminate. An ultimate path to predict the mechanical properties of laminated composites on the perspective of the material, orientation, and thickness has been developed. By calculating the mechanical properties using Chamis model then an Objectif function with five norms, these norms allow the mechanical properties to be examined and the ultimate answer to be predicted. Another model discusses an alternative concept of equivalent lamina elements (ELEs) by first using Chamis model for hybrid composites. Next, the ELEs are laminated in the direction and integrated into the compliance matrix for each ply. In addition, four new Generalization models for equivalence in thickness and in angle are presented in this paper. The analytical results are validated ...
Finite-Element Formulation for Analysis of Laminated Composites
Journal of Engineering Mechanics, 1999
This paper presents a multilayered/multidirector and shear-deformable finite-element formulation of shells for the analysis of composite laminates. The displacement field is assumed continuous across the finiteelement layers through the composite thickness. The rotation field is, however, layerwise 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 cross section. The resulting through-thickness strain field is therefore discontinuous across the different material sets. Numerical results are presented to show the performance of the method.