Progressive Failure Of Composite Laminates Research Articles

A numerical framework for simulating progressive failure in composite laminates under high-cycle fatigue loading

In this work, a recently proposed high-cycle fatigue cohesive zone model, which covers crack initiation and propagation with limited input parameters, is embedded in a robust and efficient numerical framework for simulating progressive failure in composite laminates under fatigue loading. The fatigue cohesive zone model is enhanced with an implicit time integration scheme of the fatigue damage variable which allows for larger cycle increments and more efficient analyses. The method is combined with an adaptive strategy for determining the cycle increment based on global convergence rates. Moreover, a consistent material tangent stiffness matrix has been derived by fully linearizing the underlying mixed-mode quasi-static model and the fatigue damage update. The enhanced fatigue cohesive zone model is used to describe matrix cracking and delamination in laminates. In order to allow for matrix cracks to initiate at arbitrary locations and to avoid complex and costly mesh generation, the phantom node version of the eXtended finite element method (XFEM) is employed. For the insertion of new crack segments, an XFEM fatigue crack insertion criterion is presented, which is consistent with the fatigue cohesive zone formulation. It is shown with numerical examples that the improved fatigue damage update enhances the accuracy, efficiency and robustness of the numerical simulations significantly. The numerical framework is applied to the simulation of progressive fatigue failure in an open-hole [±45]-laminate. It is demonstrated that the numerical model is capable of accurately and efficiently simulating the complete failure process from distributed damage to localized failure.

A single-layer Peridynamic model for failure analysis of composite laminates

Computational efficiency is one of the major concerns when applying traditional Peridynamics (PD) to model laminated composites. This paper proposes a highly efficient bond-based PD model for characterizing the deformation and the progressive damage behavior of laminated composites by describing laminates with a single layer of material points. The computational cost is significantly decreased due to that far fewer material points are needed to be considered during the calculation in the single-layer material point model (SLMPM). The model is validated through simulations of deformation and progressive failure in composite laminates. The deformation response is compared to ABAQUS and conventional PD results, as well as the running time compared to conventional PD. The damage prediction results are verified by experiments. It has been demonstrated that the computational efficiency of the proposed model is highly improved compared to the traditional model.

Progressive Failure Analysis of Composite Laminates Subjected to Transverse Loading with Augmented Finite Element Method

In this paper, two-dimensional (2D) orthotropic augmented finite element method (A-FEM) is applied to account for progressive failure of composite laminates under transverse loading, which considers all major cracking modes (delamination, fiber kinking/rupture matrix cracking). High-fidelity simulations of different stacking composite laminates under transverse loading are implemented. Both predicted load−deflection curves and damage evolution are in good agreement with that of experimental results, which demonstrates the numerical capability of A-FEM. In addition, the influence of stacking sequence on the failure mechanism is also studied by predicted damage evolution of laminates with different stacking sequence [Formula: see text], [Formula: see text] and [Formula: see text]. Results show that the tensile matrix crack in the bottom laminar is always the first damage mode for the composite laminate, and the subsequent crack propagation is related to ply orientation of adjacent plies which have a blocking effect on crack propagation.

Adaptive multi-fidelity (AMF) modelling of progressive damage in notched composite laminates

In recent years, high-fidelity simulations with discrete crack modelling techniques have been shown to accurately model the mechanics of progressive failure in composite laminates. However, these require high computational effort and are currently not practical beyond small coupon-sized specimens with a few tens of plies. In this paper, an adaptive multi-fidelity (AMF) modelling approach is proposed, wherein actively damaging areas are modelled with high-fidelity three-dimensional (3D) brick elements and discrete cracks, while dormant and inactive sites are modelled with lower-fidelity shell elements and smeared cracks. The transition criteria between the two levels of modelling are studied in order to preserve as much fidelity to the physics as necessary while improving computational efficiency. The results are benchmarked with that of high-fidelity simulations and experimental data of open-hole tension (OHT) of cross-ply and quasi-isotropic laminates in the literature.

A review of phase-field models, fundamentals and their applications to composite laminates

Innovations of advanced materials have been at the core of most engineering technologies, devices and systems. Composite laminates in particular have been extensively employed in many major and advanced industries including aircraft, maritime transport, and automobiles. Failure in composite structures is critical and often complicated, and that is the consequence of the evolution of and interactions among the constitutive fracture events (e.g., matrix cracking, fibre/matrix debonding, delamination, fibre breakage, fibre kinking). Accurate prediction of progressive failure in composite laminates is crucial for the development and design of most lightweight components and structures. This paper, for the first time, outlines a critical review on the developments and recent applications of regularized phase field models for failure problems in composite laminates and structures. Fundamentals of the phase field models are introduced and the developments of the regularized model from different aspects for the modeling are reviewed. Phase field models as well as the modeling strategies from different levels of idealization, i.e., microscopic, mesoscopic and macroscopic length scales are presented. The realization of existing widely used models such as cohesive zone model, plasticity, and damage initiation criterion and energy decomposition into the phase field model is also addressed. Typical applications of the phase field models in composite laminate modeling are discussed.

An auto-generated geometry-based discrete finite element model for damage evolution in composite laminates with arbitrary stacking sequence

Stiffness degradation and progressive failure of composite laminates are complex processes involving evolution and multi-mode interactions among fiber fractures, intra-ply matrix cracks and inter-ply delaminations. This paper presents a novel finite element model capable of explicitly treating such discrete failures in laminates of random layup. Matching of nodes is guaranteed at potential crack bifurcations to ensure correct displacement jumps near crack tips and explicit load transfer among cracks. The model is entirely geometry-based (no mesh prerequisite) with distinct segments assembled together using surface-based tie constraints, and thus requires no element partitioning or enrichment. Several numerical examples are included to demonstrate the model’s ability to generate results that are in qualitative and quantitative agreement with experimental observations on both damage evolution and tensile strength of specimens. The present model is believed unique in realizing simultaneous and accurate coupling of all three types of failures in laminates having arbitrary ply angles and layup.

A novel mode-dependent and probabilistic semi-discrete damage model for progressive failure analysis of composite laminates - Part II: Applications to unnotched and open-hole tensile specimens

A new method is introduced in part I of this two-part paper [1] to model the progressive failure of composite laminates. In this second part, the method is applied to unnotched (UNT) and open hole tensile (OHT) specimens. With semi-discrete meshing features and a randomized material distribution, the proposed model is capable of capturing both ultimate failure and damage progression. The increase of crack density and splitting as well as fiber failure localization are demonstrated on the basis of the cross-ply tensile specimen. Similar mechanisms, including free edge cracking, are predicted in the more complex (50/40/10) layup. With a simple technique, the meshes are efficiently generated for unnotched and notched specimens using Abaqus CAE/ Python scripting. As a result, the model is able to capture the discrete cracking near the hole as well as stress concentrations using a locally refined mesh region. By unifying features of both smeared and discrete methods, the presented semi-discrete damage model (SD2M) is seen to provide a pathway to model a variety of failure mechanisms and their interactions fairly accurately and efficiently, leading to very good predictions of ultimate strengths.

Multi-scale modelling of dynamic progressive failure in composite laminates subjected to low velocity impact

This paper aims to investigate the structural mechanical responses and progressive damage behaviors of composite laminates subjected to low velocity impact. First, a three-dimensional multi-scale model based on micromechanics of failure (MMF) criterion with new damage evolution laws is introduced for intralaminar damage, which considers the different mechanical behaviors of the microscopic constituents for fiber and matrix. The macroscopic damage variables of the new damage evolution laws are directly evaluated by the degraded elastic parameters of the microscopic constituents calculated from representative volume elements (RVEs). Second, by using this multi-scale approach, the relationship between macroscopic stress and microscopic stress is established by stress amplification factors (SAFs) through the RVEs using ABAQUS-PYTHON scripting language. The proposed model is implemented by the user-defined material subroutine VUMAT built on ABAQUS/Explicit platform, and the bilinear cohesive model in ABAQUS is employed to capture the onset and progression of interlaminar delamination. Finally, impact numerical simulation for the impact force-time/central displacement curves and energy dissipation is performed on three composite laminates with different layup patterns. Relatively good agreements are achieved between the experimental and numerical results, which validates the effectiveness of the multi-scale model.

A separable cohesive element for modelling coupled failure in laminated composite materials

A three-dimensional separable cohesive element (SCE) is proposed to enable the modelling of interaction between matrix cracking and interfacial delamination in laminated fibre-reinforced composite materials. It is demonstrated that traditional cohesive elements are incapable of modelling the coupled failure mechanisms accurately if partitioning is not allowed. The SCE may be partitioned according to the configuration and geometry of matrix cracks in adjacent plies, thus maintaining appropriate connection between plies. Physically, the original interface is split and new interfaces are formed to bond the homologous cracked solids during fracturing process. The stress concentration induced by matrix cracks and the load transfer from cracked solid elements to interface cohesive element are effectively modelled. A comprehensive set of cases of multiple matrix crack configurations from plies of different fiber angles is considered. The proposed SCE is applied to model progressive failure in composite laminates and the results are found to agree with experiments.

Integrated XFEM-CE analysis of delamination migration in multi-directional composite laminates

Progressive damage and failure in composites are generally complex and involve multiple interacting failure modes. Depending on factors such as lay-up sequence, loading and specimen configurations, failure may be dominated by extensive matrix crack-delamination interactions, which are very difficult to model accurately. The present study further develops an integrated extended finite element method (XFEM) and cohesive element (CE) method for three-dimensional (3D) delamination migration in multi-directional composite laminates, and validates the results with experiment performed on a double-cantilever beam (DCB). The plies are modeled by using XFEM brick elements, while the interfaces are modeled using CEs. The interaction between matrix crack and delamination is achieved by enriching the nodes of cohesive element. The mechanisms of matrix fracture and delamination migration are explained and discussed. Matrix crack initiation and propagation can be predicted and delamination migration is also observed in the results. The algorithm provides for the prediction of matrix crack angles through the ply thickness. The proposed method provides a platform for the realistic simulation of progressive failure of composite laminates.

Puck 파손기준-손상역학 연계이론을 활용한 적층 복합재료의 점진적 파손해석기법 개발

In the present study, an evaluation method for progressive failure of composite laminates has been proposed based on Puck's failure criterion and damage mechanics. The initial failure (or initiation of crack/delamination) has been assessed using Puck's failure criterion, and the progressive failure (or growth of crack/delamination) has been evaluated using fiber- and matrix-dependent damage variables. Based on Puck's failure criterion-damage mechanics coupling theories, the ABAQUS user-defined subroutine UMAT has been developed in order to analyze the progressive failure of glass/carbon fiber-reinforced composite laminates efficiently. In addition, the developed subroutine has been applied to progressive failure problem of industrial composite laminates, and the analysis results has been compared to experimental results which have been already reported in publications. It was confirmed that the simulation results were coincided well with the reported composite failure results.

Initial and progressive failure analyses for composite laminates using Puck failure criterion and damage-coupled finite element method

In the present study, an evaluation method for the initial and progressive failure of composite laminates was proposed based on the Puck failure criterion and damage mechanics, respectively. In other words, the initial failure (crack initiation in the fiber and/or matrix) and progressive failure (crack growth in the fiber and/or matrix) were evaluated using the Puck failure criterion, and fiber- and matrix-dependent damage variables, respectively. In addition, the ABAQUS user-defined subroutine UMAT was developed based on coupling theories for the failure criterion and damage mechanics in order to efficiently analyze the progressive failure phenomenon in glass/carbon fiber-reinforced composite laminates. The developed subroutine was applied to the failure of industrial composite laminates, and the analysis results were compared to the experimental/numerical results previously reported in the literature. This comparative study confirmed that the simulation results were in good agreement with the reported composite failure results.

Recent efforts toward modeling interactions of matrix cracks and delaminations: an integrated XFEM-CE approach

This paper presents a novel integrated approach using the extended finite element method (XFEM) and cohesive elements (CEs) for modeling three-dimensional (3D) delaminations, matrix cracks, and their interactions in progressive failure of composite laminates. In the proposed XFEM-CE approach, the matrix cracks are explicitly modeled by the XFEM through nodal enrichment and element partition, and the inter-ply delaminations are modeled by cohesive elements through traction–separation law. An XFEM-based cohesive element enrichment scheme is developed in order to properly model the interactions between the delaminations and matrix cracks. It is critical to enrich the cohesive elements at the local juncture where cracks meet, in order to obtain the correct crack path interactions. Examples are presented for failure analysis of double-cantilever-beam and end-notch-flexure laminates with different layups. The results show strong explicit matrix crack–delamination interactions in these laminates. This work presents another significant development of a computational platform for realistic modeling of progressive damage in composites.

Simulating progressive failure of composite laminates including in-ply and delamination damage effects

A finite element (FE) model, which includes in-ply and delamination damage effects, is developed for the progressive failure analysis of composite laminates. A combined elastoplastic damage model which accounts for both plasticity and damage effects is used to represent the mechanical response of composite layers and is implemented in the FE code Abaqus using user-defined material subroutine UMAT. A cohesive zone model based on cohesive elements available in Abaqus is employed to simulate delamination behaviour in the adhesive interfaces. Continuum shell elements and cohesive elements are stacked together to simulate composite and adhesive layers, respectively. The model is applied to the progressive failure analysis of AS4/PEEK composite laminates subjected to in-plane tensile and out-of-plane transverse low-velocity impact loadings. It is shown that the model can be successfully applied to the simulations of composite laminates susceptible to delamination failure.

English

Glass fiber reinforced polymer (GFRP) laminates have a high damping characteristic which can retard ultra-high frequency guided wave signals from propagating along the plate. Owing to this, the identification of an effective area for sensor location is essential. Appropriate signal processing, including wavelet analysis was done, in order to observe the details of an acoustic emission (AE) signal which was emitted at a distance from it source. This study reveals that it is necessary to consider the near field and far field effects of AE signal attenuation, in particular, to determine a composite's micro failure characterization. Consequently, this attenuation behavior was used to develop the non-velocity based source mapping to monitor the progressive failure in composite laminates. This paper details the outcomes of the signal energy attenuation method with an improved algorithm for progressive failure monitoring in fiberglass reinforced composite laminates and the 'effective length' for better AE detection.

Predicting the nonlinear response and progressive failure of composite laminates under triaxial loading: Correlation with experimental results

This article represents our contribution to Part B of the 2nd Worldwide Failure Exercise (WWFE-II), where comparisons between epoxy/lamina/laminate response and failure predictions, based on maximum strain failure criterion, and experimental results are made. Correlations between actual test data and our nonlinear stress-strain response and failure envelope predictions under multi-axial loading for 12 different case studies are presented and discussed. Although our approach to modeling composite failure ranked high when applied to biaxial in-plane loading analysis, the theory does not consistently capture the inherent strengthening mechanisms that can be attributed to triaxial loading and hydrostatic pressure. It is expected that the incorporation of a strain-based ply-level failure criterion that introduces some form of strengthening mechanism under a three-dimensional stress state would significantly improve the accuracy of our predictions.

Predicting the nonlinear response and progressive failure of composite laminates under tri-axial loading

As a part of the Second World-Wide Failure Exercise, a three-dimensional nonlinear maximum progressive strain model, based on laminate analysis, is employed to make blind predictions for 12 test cases representing failure envelopes and stress strain curves for isotropic, unidirectional, and multidirectional composite laminates. This approach allows for redistribution of ply stresses and differentiation of the various potential modes of failure. These cases include initial and final ply failure envelopes under tri-axial loading, as well as 3 cases, requiring nonlinear stress–strain analysis. Comparison of predictions with actual experimental data will be made in Part B of the Second World-Wide Failure Exercise.

A combined elastoplastic damage model for progressive failure analysis of composite materials and structures

The paper is concerned with the development and verification of a combined elastoplastic damage model for the progressive failure analysis of composite materials and structures. The model accounts for the irreversible strains caused by plasticity effects and material properties degradation due to the damage initiation and development. The strain-driven implicit integration procedure is developed using equations of continuum damage mechanics, plasticity theory and includes the return mapping algorithm. A tangent operator consistent with the integration procedure is derived to ensure a computational efficiency of the Newton–Raphson method in the finite element analysis. The algorithm is implemented in Abaqus as a user-defined subroutine. The efficiency of the constitutive model and computational procedure is demonstrated using the analysis of the progressive failure of composite laminates containing through holes and subjected to in-plane uniaxial tensile loading. It has been shown that the predicted results agree well with the experimental data reported in the literature.

Computational modeling of complex failure mechanisms in laminates

A computational framework for the simulation of progressive failure in composite laminates is presented. The phantom-node method (a variation to the XFEM) is used for a mesh-independent representation of matrix cracks as straight discontinuities in the displacement field. Furthermore, interface elements are used for delamination and a continuum damage model for fiber failure. The framework is validated against experimental observations for open-hole tests and compact tension tests. It is shown that different failure mechanisms are captured well, which allows for the prediction of size effects.

Continuum Models for the Analysis of Progressive Failure in Composite Laminates

The performance of continuum material models for mesolevel modeling of progressive failure in composite laminates is examined. Two different continuum models are used: a continuum damage model and a softening plasticity model. It is shown how mesh-independent results can be obtained with both models by introducing a viscosity term. The capability of the models to represent complex intraply failure behavior is assessed by means of an analysis of a notched plate, where interface elements are used to model delamination. Proper results from different modeling approaches are shown, but upon calibration a limitation of the continuum approach in the representation of matrix failure is encountered. With a second example, this limitation is emphasized further and explained as a consequence of the homogenization that is inherent in continuum models, irrespective of the applied failure criteria and material degradation laws.