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Luca Di Stasio - One of the best experts on this subject based on the ideXlab platform.
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finite element solution of the fiber matrix interface crack problem convergence properties and mode mixity of the Virtual crack closure Technique
Finite Elements in Analysis and Design, 2019Co-Authors: Luca Di Stasio, Zoubir AyadiAbstract:Abstract The bi-material interface arc crack has been the focus of interest in the composite community, where it is usually referred to as the fiber-matrix interface crack. In this work, we investigate the convergence properties of the Virtual Crack Closure Technique (VCCT) when applied to the evaluation of the Mode I, Mode II and total Energy Release Rate of the fiber-matrix interface crack in the context of the Finite Element Method (FEM). We first propose a synthetic vectorial formulation of the VCCT. Thanks to this formulation, we study the convergence properties of the method, both analytically and numerically. It is found that Mode I and Mode II Energy Release Rate (ERR) possess a logarithmic dependency with respect to the size of the elements in the crack tip neighborhood, while the total ERR is independent of element size.
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energy release rate of fiber matrix interface crack growth in cross ply laminates under transverse loading effect of the 0 90 interface and of 0 layer thickness
2019Co-Authors: Luca Di Stasio, Janis Varna, Zoubi AyadiAbstract:Models of Representative Volume Elements (RVEs) of cross-ply laminates with different geometric configurations and damage states are studied. Debond growth is characterized by the estimation of the Mode I and Mode II Energy Release Rate (ERR) using the Virtual Crack Closure Technique (VCCT). It is found that the presence of the 0/90 interface and the thickness of the 0 layer have no effect, apart from laminates with ultra-thin 90 plies where it is however modest. The present analysis support the claim that debond growth is not affected by the ply-thickness effect.
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Energy release rate of the fiber/matrix interface crack in UD composites under transverse loading: debond-debond and debond-free boundary interactions
2019Co-Authors: Luca Di Stasio, Janis Varna, Zoubir AyadiAbstract:The effects of crack shielding, finite thickness of the composite and fiber content on fiber/matrix debond growth in thin unidirectional composites are investigated analyzing Representative Volume Elements (RVEs) of different ordered microstructures. Debond growth is characterized by estimation of the Energy Release Rates (ERRs) in Mode I and Mode II using the Virtual Crack Closure Technique (VCCT) and the J-integral. It is found that increasing fiber content, a larger distance between debonds in the loading direction and the presence of a free surface close to the debond have all a strong enhancing effect on the ERR. The presence of fully bonded fibers in the composite thickness direction has instead a constraining effect, and it is shown to be very localized. An explanation of these observations is proposed based on mechanical considerations.
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Finite Element solution of the fiber/matrix interface crack problem: convergence properties and mode mixity of the Virtual Crack Closure Technique
2019Co-Authors: Luca Di Stasio, Zoubir AyadiAbstract:The bi-material interface arc crack has been the focus of interest in the composite community, where it is usually referred to as the fiber-matrix interface crack. In this work, we investigate the convergence properties of the Virtual Crack Closure Technique (VCCT) when applied to the evaluation of the Mode I, Mode II and total Energy Release Rate of the fiber-matrix interface crack in the context of the Finite Element Method (FEM). We first propose a synthetic vectorial formulation of the VCCT. Thanks to this formulation, we study the convergence properties of the method, both analytically and numerically. It is found that Mode I and Mode II Energy Release Rate (ERR) possess a logarithmic dependency with respect to the size of the elements in the crack tip neighborhood, while the total ERR is independent of element size.
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Energy release rate of fiber/matrix interface crack growth in cross-ply laminates under transverse loading: effect of the 0° /90° interface and of 0° layer thickness
2019Co-Authors: Luca Di Stasio, Janis Varna, Zoubir AyadiAbstract:Models of Representative Volume Elements (RVEs) of cross-ply laminates with different geometric configurations and damage states are studied. Debond growth is characterized by the estimation of the Mode I and Mode II Energy Release Rate (ERR) using the Virtual Crack Closure Technique (VCCT). It is found that the presence of the 0/90 interface and the thickness of the 0 layer have no effect, apart from laminates with ultra-thin 90 plies where it is however modest. The present analysis support the claim that debond growth is not affected by the ply-thickness effect.
Zoubir Ayadi - One of the best experts on this subject based on the ideXlab platform.
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finite element solution of the fiber matrix interface crack problem convergence properties and mode mixity of the Virtual crack closure Technique
Finite Elements in Analysis and Design, 2019Co-Authors: Luca Di Stasio, Zoubir AyadiAbstract:Abstract The bi-material interface arc crack has been the focus of interest in the composite community, where it is usually referred to as the fiber-matrix interface crack. In this work, we investigate the convergence properties of the Virtual Crack Closure Technique (VCCT) when applied to the evaluation of the Mode I, Mode II and total Energy Release Rate of the fiber-matrix interface crack in the context of the Finite Element Method (FEM). We first propose a synthetic vectorial formulation of the VCCT. Thanks to this formulation, we study the convergence properties of the method, both analytically and numerically. It is found that Mode I and Mode II Energy Release Rate (ERR) possess a logarithmic dependency with respect to the size of the elements in the crack tip neighborhood, while the total ERR is independent of element size.
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Energy release rate of the fiber/matrix interface crack in UD composites under transverse loading: debond-debond and debond-free boundary interactions
2019Co-Authors: Luca Di Stasio, Janis Varna, Zoubir AyadiAbstract:The effects of crack shielding, finite thickness of the composite and fiber content on fiber/matrix debond growth in thin unidirectional composites are investigated analyzing Representative Volume Elements (RVEs) of different ordered microstructures. Debond growth is characterized by estimation of the Energy Release Rates (ERRs) in Mode I and Mode II using the Virtual Crack Closure Technique (VCCT) and the J-integral. It is found that increasing fiber content, a larger distance between debonds in the loading direction and the presence of a free surface close to the debond have all a strong enhancing effect on the ERR. The presence of fully bonded fibers in the composite thickness direction has instead a constraining effect, and it is shown to be very localized. An explanation of these observations is proposed based on mechanical considerations.
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Finite Element solution of the fiber/matrix interface crack problem: convergence properties and mode mixity of the Virtual Crack Closure Technique
2019Co-Authors: Luca Di Stasio, Zoubir AyadiAbstract:The bi-material interface arc crack has been the focus of interest in the composite community, where it is usually referred to as the fiber-matrix interface crack. In this work, we investigate the convergence properties of the Virtual Crack Closure Technique (VCCT) when applied to the evaluation of the Mode I, Mode II and total Energy Release Rate of the fiber-matrix interface crack in the context of the Finite Element Method (FEM). We first propose a synthetic vectorial formulation of the VCCT. Thanks to this formulation, we study the convergence properties of the method, both analytically and numerically. It is found that Mode I and Mode II Energy Release Rate (ERR) possess a logarithmic dependency with respect to the size of the elements in the crack tip neighborhood, while the total ERR is independent of element size.
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Energy release rate of fiber/matrix interface crack growth in cross-ply laminates under transverse loading: effect of the 0° /90° interface and of 0° layer thickness
2019Co-Authors: Luca Di Stasio, Janis Varna, Zoubir AyadiAbstract:Models of Representative Volume Elements (RVEs) of cross-ply laminates with different geometric configurations and damage states are studied. Debond growth is characterized by the estimation of the Mode I and Mode II Energy Release Rate (ERR) using the Virtual Crack Closure Technique (VCCT). It is found that the presence of the 0/90 interface and the thickness of the 0 layer have no effect, apart from laminates with ultra-thin 90 plies where it is however modest. The present analysis support the claim that debond growth is not affected by the ply-thickness effect.
Aniello Riccio - One of the best experts on this subject based on the ideXlab platform.
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Influence of Manufacturing Defects on the Mechanical Behaviour of All-Composite Wing under Service Load Conditions
Key Engineering Materials, 2017Co-Authors: Aniello Riccio, Angela Russo, Andrea Sellitto, G. Pezone, J. San Millan, I. ArmendarizAbstract:In this paper, the damage behaviour of aerospace composite structures has been studied. The analysed structure is an all-composite wing with inter-laminar manufacturing induced damage. The manufacturing induced delaminations are located at the leading edge on the extrados and in the area near the fuselage. Different analyses have been performed to correctly predict the pre-existent damages evolution under service loading conditions. Preliminary linear buckling analyses have been performed to check for instability of the delaminations under service loads; then the risk of delaminations’ propagation has been evaluated by means of a Virtual Crack Closure Technique based approach.
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a global local finite element approach for predicting interlaminar and intralaminar damage evolution in composite stiffened panels under compressive load
Applied Composite Materials, 2011Co-Authors: Elisa Pietropaoli, Aniello RiccioAbstract:This paper addresses the prediction of intralaminar and interlaminar damage onset and evolution in composite structures through the use of a finite element based procedure. This procedure joins methodologies whose credibility has been already assessed in literature such as the Virtual Crack Closure Technique (for delamination) and the ply discount approach (for matrix/fiber failures). In order to establish the reliability of the procedure developed, comparisons with literature experimental results on a stiffened panel with an embedded delamination are illustrated. The methodology proposed, implemented in ANSYS © as post-processing routines, is combined with a finite element model of the panel, built by adopting both shell and solid elements within the frame of an embedded global/local approach to connect differently modelled substructures.
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Formulation and assessment of an enhanced finite element procedure for the analysis of delamination growth phenomena in composite structures
Composites Science and Technology, 2011Co-Authors: Elisa Pietropaoli, Aniello RiccioAbstract:An existing procedure based on the combined use of the Virtual Crack Closure Technique and of a fail release approach for the analysis of delamination growth phenomena in composite structures has been enhanced with a front-tracing algorithm and suitable expressions for the evaluation of the Strain Energy Release Rate when dealing with non-smoothed delamination fronts. The enhanced procedure has been implemented into a commercial finite element software by means of user subroutines and applied to the analysis of a composite stiffened panel with an embedded delamination under compressive load. The effectiveness and robustness of the enhanced procedure have been assessed by comparing literature experimental data and numerical results obtained by using different mesh densities in the damaged area (global/local approach).
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on the robustness of finite element procedures based on Virtual crack closure Technique and fail release approach for delamination growth phenomena definition and assessment of a novel methodology
Composites Science and Technology, 2010Co-Authors: Elisa Pietropaoli, Aniello RiccioAbstract:Numerical procedures based on the combined use of the Virtual Crack Closure Technique and of a fail release approach have been widely used to simulate delamination growth phenomena of composite material structures. This paper starts explaining why this kind of methodologies might not be robust due to mesh and load step size dependency and introduces a novel approach able to cope with the problems identified. Finally the effectiveness and robustness of the proposed procedure, implemented into a commercial finite element software by means of user subroutines, are assessed by comparing the obtained numerical results for a delamination growth phenomenon against literature experimental data on a stiffened panel with a circular embedded delamination under compressive load.
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modeling damage propagation in composite plates with embedded delamination under compressive load
Journal of Composite Materials, 2008Co-Authors: Aniello Riccio, Elisa PietropaoliAbstract:A numerical procedure aimed at simulating the structural behavior of delaminated composite plates under compressive load, is developed and presented in this article. Although delamination buckling and growth have been widely studied in the literature, in this article the effect of fiber—matrix failure on the buckling behavior of a delaminated structure up to final failure is investigated in detail. A geometrically non linear finite element (FE) approach is adopted for elastic instability simulation, the modified Virtual crack closure Technique (MVCCT) is used for the energy release rate (ERR) evaluation at the delamination front and fracture mechanics based progressive damage approach is introduced for the simulation of fiber—matrix damage onset and evolution. Comparisons of numerical results with existing experimental data on composite panels with an embedded circular delamination under compressive load, are presented for preliminary validation purposes. Furthermore, the influence of the different failur...
Sherrill B Biggers - One of the best experts on this subject based on the ideXlab platform.
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calculation of transient strain energy release rates under impact loading based on the Virtual crack closure Technique
International Journal of Impact Engineering, 2007Co-Authors: De Xie, Sherrill B BiggersAbstract:Abstract This paper describes an interface element to calculate the strain energy release rates based on the Virtual crack closure Technique (VCCT) in conjunction with finite element analysis (FEA). A very stiff spring is placed between the node pair at the crack tip to calculate the nodal forces. Dummy nodes are introduced to extract information for displacement openings behind the crack tip and the Virtual crack jump ahead of the crack tip. This interface element leads to a direct calculation of the strain energy release rate (both components GI and GII) within a finite element analysis without extra post-processing. Several examples of stationary cracks under impact loading were examined. Dynamic stress intensity factors were converted from the calculated transient strain energy release rate for comparison with the available solutions by the others from numerical and experimental methods. The accuracy of the element is validated by the excellent agreement with these solutions. No convergence difficulty has been encountered for all the cases studied. Neither special singular elements nor the collapsed element Technique is used at the crack tip. Therefore, the fracture interface element for VCCT is shown to be simple, efficient and robust in analyzing crack response to the dynamic loading. This element has been implemented into commercial FEA software ABAQUS® with the user defined element (UEL) and should be very useful in performing fracture analysis at a structural level by engineers using ABAQUS®.
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progressive crack growth analysis using interface element based on the Virtual crack closure Technique
Finite Elements in Analysis and Design, 2006Co-Authors: Sherrill B BiggersAbstract:This paper introduces an interface element to solve 2D progressive crack growth problems under mixed-mode loading. The interface element is developed to calculate the strain energy release rates based on the Virtual crack closure Technique (VCCT) in conjunction with finite element analysis (FEA). A very stiff spring is placed between the node pair at the crack tip to calculate the internal forces. Dummy nodes are introduced to extract information for displacement openings behind the crack tip and the Virtual crack jump ahead of the crack tip. Therefore, with this interface element, strain energy release rates (GI and GII) can be calculated simultaneously as FEA is performed. Furthermore, with the implementation of fracture criteria, crack growth can be also directly analyzed with a fracture mechanics approach. Three classic examples for stationary cracks and three benchmark examples for static crack growth were examined. The accuracy of the element is validated by the excellent agreement with analytical solutions of these examples. No convergence difficulty has been encountered during the crack growth analyses. The fracture interface element for VCCT is, therefore, simple, efficient and robust in analyzing any 2D crack growth problems. This element has been implemented into commercial FEA software ABAQUS® with UEL and should be very useful in designing for enhanced structural integrity in general cases where crack initiation, crack growth, and crack arrest features are of concern.
R. Krueger - One of the best experts on this subject based on the ideXlab platform.
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The Virtual crack closure Technique for modeling interlaminar failure and delamination in advanced composite materials
Numerical Modelling of Failure in Advanced Composite Materials, 2015Co-Authors: R. KruegerAbstract:This chapter gives an overview of the Virtual crack closure Technique (VCCT) and provides insight into its application and pitfalls. We give equations for two-dimensional elements, as well as three-dimensional solid and plate/shell elements. This chapter presents necessary modifications for the use of the method with geometrically nonlinear finite element analysis and corrections required for elements at the crack tip with different lengths and widths. Modeling and implementation aspects are discussed, as well as mixed-mode fracture criteria and standardized test methods to obtain fracture toughness data used in the analyses. Additionally, we address problems associated with cracks or delaminations located at a bimaterial interface. Further, in this chapter we demonstrate the development and application of benchmark examples for the assessment of delamination propagation capabilities. Evolving methods and future trends are introduced and recommendations for the successful use of VCCT are provided together with an application example and extensive references to key publications.
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influence of finite element software on energy release rates computed using the Virtual crack closure Technique
2013Co-Authors: R. Krueger, Dirk Goetze, Jonathon RansomAbstract:Strain energy release rates were computed along straight delamination fronts of Double Cantilever Beam, End-Notched Flexure and Single Leg Bending specimens using the Virtual Crack Closure Technique (VCCT). Th e results were based on finite element analyses using ABAQUS# and ANSYS# and were calculated from the finite element results using the same post-processing routine to assure a consistent procedure. Mixed-mode strain energy release rates obtained from post-processing finite elem ent results were in good agreement for all element types used and all specimens modeled. Compared to previous studies, the models made of s olid twenty-node hexahedral elements and solid eight-node incompatible mode elements yielded excellent results. For both codes, models made of standard brick elements and elements with reduced integration did not correctly capture the distribution of the energy release rate acr oss the width of the specimens for the models chosen. The results suggested that element types with similar formulation yield matching results independent of the finite element software used. For comparison, m ixed-mode strain energy release rates were also calculated within ABAQUS#/Standard using the VCCT for ABAQUS# add on. For all specimens mod eled, mixed-mode strain energy release rates obtained from ABAQUS# finite element results using post-processing were almost identical to re sults calculated using the VCCT for ABAQUS# add on.
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Virtual crack closure Technique history approach and applications
Applied Mechanics Reviews, 2004Co-Authors: R. KruegerAbstract:Abstract : An overview of the Virtual crack closure Technique is presented. The approach used is discussed, the history summarized, and insight into its applications provided. Equations for two-dimensional quadrilateral elements with linear and quadratic shape functions are given. Formula for applying the Technique in conjuction with three-dimensional solid elements as well as plate/shell elements are also provided. Necessary modifications for the use of the method with geometrically nonlinear finite element analysis and corrections required for elements at the crack tip with different lengths and widths are discussed. The problems associated with cracks or delaminations propagating between different materials are mentioned briefly, as well as a strategy to minimize these problems. Due to an increased interest in using a fracture mechanics based approach to assess the damage tolerance of composite structures in the design phase and during certification, the engineering problems selected as examples and given as references focus on the application of the Technique to components made of composite materials.
