Phenomenological Model of Orthotropic Damage in Polymer Matrix Composites (original) (raw)
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Damage Evolution In Laminated Composite Materials
Proceedings of Dansk Metalurgisk …
The effects of extreme environmental conditions on damage evolution and lifetime of long fiber polymer based composites are studied experimentally and theoretically. Altered temperature and exposure to a salt water are the extreme environmental conditions that are considered in this study. The continuum damage mechanics is considered as a promising approach to develop thermodynamically consistent formulation of constitutive law for media with damage, that would account for effects of temperature changes (non-isothermal conditions) and environmental (moisture) conditions as they affect the damage evolution. This is because the additional internal state variables (ISV), that would account for considered phenomenon, can be included. The thermodynamically consistent damage dependent lamination theory is used at this point of the study, to describe inelastic response to the applied load for a long fiber composite laminates at reference environmental conditions (ambient room conditions). In this study, the internal state variables that accounts for damage of UD composite in fiber direction are formulated within the terms of the theory, and the function that describe the corresponding internal state variable are determined experimentally. The ISV evolution law associated with damage in fiber direction are additionally formulated within the terms of the model. The stiffness degradation is associated with corresponding damage evolution providing the tool for experimental determination of ISV accounting for corresponding damage. The experimentally determined functions of ISV are used to predict the lifetime of the laminates with arbitrary layup.
A continuum damage model for composite laminates: Part I – Constitutive model
Mechanics of Materials, 2007
A continuum damage model for the prediction of the onset and evolution of intralaminar failure mechanisms and the collapse of structures manufactured in fiber-reinforced plastic laminates is proposed. The failure mechanisms occurring in the longitudinal and transverse directions of a ply are represented by a set of scalar damage variables. Crack closure effects under load reversal are taken into account by using damage variables that are established as a function of the sign of the components of the stress tensor. Damage activation functions based on the LaRC04 failure criteria are used to predict the different failure mechanisms occurring at the ply level.
Computational Materials Science, 2008
In the paper a new phenomenological model has been proposed in order to describe a gradual degradation of polymer laminates. The constitutive relations were expressed as a tensor function of two variables: the stress tensor r ij and the damage tensor D ij. The general formulation concerns 2-D and 3-D description of material with internal damage. Application of the theory was illustrated by considering gradual degradation of the laminate polymer composite. The evolution laws for the elastic moduli and the Poisson's ratio were proposed and experimentally verified.
Interlaminar damage model for polymer matrix composites
Journal of composite …, 2003
A constitutive model for fiber reinforced composite materials with damage and unrecoverable deformation, which for the first time accounts for interlaminar damage, is presented. The formulation is based on Continuous Damage Mechanics coupled with Classical Plasticity Theory in a consistent thermodynamic framework using internal state variables. In-plane damage and novel formulation of interlaminar damage are included in order to describe the main failure modes of laminates structures. A novel implementation of the constitutive model into a finite element formulation incorporating geometric nonlinearity is presented. The model uses a small number of adjustable parameters, which are identified from available experimental data. Comparisons with experimental data for composite laminates under torsion loading are shown to validate the model for interlaminar damage. Coupled material and geometrical non-linear analysis with simultaneous in-plane and interlaminar damage is demonstrated. The effect of warping on interlaminar damage is shown to be significant.
Numerical Simulation on Damage Mode Evolution in Composite Laminate
International Journal of Advanced Computer Science and Applications, 2014
The present work follows numerous numerical simulation on the stress field analysis in a cracked cross-ply laminate. These results lead us to elaborate an energy criterion. This criterion is based on the computation of the partial strain energy release rate associated with all the three damage types: transverse cracking, longitudinal cracking and delamination. The related criterion, linear fracture based approach, is used to predict and describe the initiation of the different damage mechanisms. With this approach the influence of the nature of the material constituent on the damage mechanism is computed. We also give an assessment of the strain energy release rates associated with each damage mode. This criterion checked on glass-epoxy and graphite-epoxy composite materials will now be used in future research on new bio-based composite in the laboratory.
Modeling damage in polymeric composites
2008
We postulate that dominant damage modes in a fiber-reinforced laminated composite are fiber breakage, matrix cracking, fiber/matrix debonding, and delamination/sliding. The first three damage modes are represented by internal variables with their development governed by constitutive relations.
Mechanics of Materials, 2007
A continuum damage model for the prediction of the onset and evolution of intralaminar failure mechanisms and the collapse of structures manufactured in fiber-reinforced plastic laminates is proposed. The failure mechanisms occurring in the longitudinal and transverse directions of a ply are represented by a set of scalar damage variables. Crack closure effects under load reversal are taken into account by using damage variables that are established as a function of the sign of the components of the stress tensor. Damage activation functions based on the LaRC04 failure criteria are used to predict the different failure mechanisms occurring at the ply level.
Composites Part B: Engineering, 2010
A constitutive model to predict stiffness reduction due to transverse matrix cracking is derived for laminae with arbitrary orientation, subject to in-plane stress, embedded in laminates with symmetric but otherwise arbitrary laminate stacking sequence. The moduli of the damaged laminate are a function of the crack densities in the damaging laminae, which are analyzed one by one. The evolution of crack density in each lamina is derived in terms of the calculated strain energy release rate and predicted as function of the applied load using a fracture mechanics approach. Unlike plasticity-inspired formulations, the proposed model does not postulate damage evolution functions and thus there is no need for additional experimental data to adjust material parameters. All that it is needed are the elastic moduli and critical energy release rates for the laminae. The reduction of lamina stiffness is an integral part of the model, allowing for stress redistribution among laminae. Comparisons with experimental data and some results from the literature are presented.
An inelastic damage model for fiber reinforced laminates
Journal of composite materials, 2002
A new model for damage behavior of polymer matrix composite laminates is presented. The model is developed for an individual lamina, and then assembled to describe the nonlinear behavior of the laminate. The model predicts the inelastic effects as reduction of stiffness and increments of damage and unrecoverable deformation. The model is defined using Continuous Damage Mechanics coupled with Classical Thermodynamic Theory. Unrecoverable deformations and Damage are coupled by the concept of effective stress. New expressions of damage and unrecoverable deformation domains are presented so that the number of model parameters is small. Furthermore, model parameters are obtained from existing test data for unidirectional laminae, supplemented by cyclic shear stress-strain data. Comparison with lamina and laminate test data are presented to demonstrate the ability of the model to predict the observed behavior.
A physically based continuum damage mechanics model for thin laminated composite structures
The present work focuses on the development, implementation, and verification of a plane-stress continuum damage mechanics (CDM) based model for composite materials. A physical treatment of damage growth based on the extensive body of experimental literature on the subject is combined with the mathematical rigour of a CDM description to form the foundation of the model. The model has been implemented in the commercial finite element code, LS-DYNA and the results of the application of the model to the prediction of impact damage growth and its effects on the impact force histories in carbon fibre reinforced plastic laminates are shown to be physically meaningful and accurate. Furthermore, it is demonstrated that the material characterization parameters can be extracted from the results of standard test methodologies for which a large body of published data already exists for many composite materials. commonly used strain equivalence approach, a material containing damage, subjected to a strain, e, and under a state of stress, r, can be represented as an equivalent undamaged material subject to the same strain, e, but under an effective stress state,r r. This can be expressed mathematically by the relation: