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Fernando Antunes - One of the best experts on this subject based on the ideXlab platform.

  • A methodology for simulating plasticity induced Crack Closure and Crack shape evolution based on elastic–plastic fracture parameters
    Engineering Fracture Mechanics, 2021
    Co-Authors: Mikel Escalero, Ricardo Branco, Miguel Muñiz-calvente, Haritz Zabala, Iker Urresti, Fernando Antunes
    Abstract:

    Abstract A methodology for simulating plasticity induced Crack Closure and Crack shape evolution based on elastic–plastic fracture parameters is proposed, which represents a new way to predict fatigue Crack growth in small and large scale yielding scenarios. The methodology consists in solving iteratively a single elastic–plastic finite element model, for which the load history is kept by remeshing and mapping and Crack advance is performed by node releasing. Aiming to illustrate and validate the approach, the growth of an initially straight Crack is simulated in a compact tension specimen subjected to small scale yielding conditions, using the plastic Crack tip opening displacement range ( Δ CTOD p ) as the Crack driving force. The predicted Crack shape shows high agreement with experimental observations and the Crack opening load trends are consistent with the literature, demonstrating that the methodology proposed can be relevant for further Crack growth studies.

  • 3D numerical study of the transient behaviour on plasticity induced Crack Closure
    2019
    Co-Authors: D Camas, Pablo Lopez-crespo, Fernando Antunes, Antonio Gonzalez-herrera
    Abstract:

    Daniel Camas, Fernando Antunes, Pablo Lopez-Crespo, Antonio Gonzalez-Herrera, 3D Numerical Study of the Transient Behaviour on Plasticity Induced Crack Closure, Abstract Booklet of the MSMF9, Edited by Pavel Sandera, Brno University of Technology, 2019, pp. 136.

  • Numerical Analysis of the Influence of Crack Growth Scheme on Plasticity Induced Crack Closure Results
    Structural Integrity, 2019
    Co-Authors: D Camas, Fernando Antunes, J. Garcia-manrique, Antonio Gonzalez-herrera
    Abstract:

    Plasticity Induced Crack Closure (PICC) has been studied by means of finite element method for a long time. Most of previous work was developed considering bi-dimensional models. During last years, the use of three-dimensional models has been extended. Nevertheless, the methodology employed has been inherited from bi-dimensional analyses. Many previous bi-dimensional analyses studied different numerical parameters and optimized them. Present computational capabilities allow a comprehensive study of the influence of different modelling parameter in a similar way to those bi-dimensional analyses. Moreover, the influence of these parameters on the obtained results along the thickness can be taken into consideration. In particular, one of the key issues is related to the Crack growth scheme. A fatigue analysis implies a Crack growth. Each change in loading and boundary conditions implies solving a nonlinear problem. It is not feasible to consider all the cycles involved in a real fatigue problem when running a finite element analysis. The computational cost is not acceptable. In the present work, a CT aluminium specimen has been modelled three-dimensionally and several calculations have been made in order to evaluate the influence of the number of load cycles between node releases. The results are analysed in terms of Crack Closure and opening values.

  • Effect of underloads on plasticity induced Crack Closure: a numerical analysis
    Journal of Engineering Materials and Technology, 2019
    Co-Authors: Fernando Antunes, Ricardo Branco, Luís Paiva, L.p. Borrego
    Abstract:

    The effect of underloads is mostly quantified by the averaged effect on the fatigue Crack growth rate, and the transient behavior is rarely investigated. The objective of this paper is to study the mechanisms behind the effect of underloads, periodic underloads, and underloads combined with overloads. A single underload smashes the material around the Crack tip, producing a depression on Crack flank and a local reduction of contact forces at the minimum load. The reduction of plastic elongation behind the Crack tip has an immediate effect on Crack opening level, which rapidly disappears with Crack propagation. The smashing associated with the compressive force occurs mainly behind the Crack tip position where the underload was applied. The effect of the underload is intimately linked to reversed plastic deformation, which explains its enhanced effect for kinematic hardening. The decrease of load below the minimum baseline load is the main loading parameter. The application of periodic underloads extends the effect of a single underload. The effect of the underload is enhanced by the presence of obstacles in the form of residual plastic deformation, which explains the great effect of underloads applied after overloads.

  • Numerical analysis of the influence of the last cycle scheme on plasticity induced Crack Closure
    Procedia Structural Integrity, 2019
    Co-Authors: D Camas, Fernando Antunes, B. Moreno, Antonio Gonzalez-herrera
    Abstract:

    Abstract Plasticity induced Crack Closure is considered the main mechanism related to the premature contact of the Crack flanks when a Crack grows under cyclic loadings. This phenomenon has been studied numerically since the early 70s, when some researchers approached to metal fatigue problems by means of the finite element analysis. The numerical analysis requires the development of a plastic wake. How this plastic wake is developed has influence on the Crack Closure results and a great impact on the computational cost. When running a finite element analysis, it is not possible to consider all the loading cycles involved in an experimental test. The numerical effort is not acceptable. Therefore, in this work, the Crack growth scheme is analyzed. In particular, the influence of the number of loading cycles after releasing the last set of nodes on plasticity induced Crack Closure results is studied. A CT aluminum specimen has been modelled three-dimensionally and several simulations have been run to evaluate the influence of the loading cycles after releasing the last set of nodes. The numerical analysis is made in terms of Crack Closure and opening values.

Ricardo Branco - One of the best experts on this subject based on the ideXlab platform.

  • A methodology for simulating plasticity induced Crack Closure and Crack shape evolution based on elastic–plastic fracture parameters
    Engineering Fracture Mechanics, 2021
    Co-Authors: Mikel Escalero, Ricardo Branco, Miguel Muñiz-calvente, Haritz Zabala, Iker Urresti, Fernando Antunes
    Abstract:

    Abstract A methodology for simulating plasticity induced Crack Closure and Crack shape evolution based on elastic–plastic fracture parameters is proposed, which represents a new way to predict fatigue Crack growth in small and large scale yielding scenarios. The methodology consists in solving iteratively a single elastic–plastic finite element model, for which the load history is kept by remeshing and mapping and Crack advance is performed by node releasing. Aiming to illustrate and validate the approach, the growth of an initially straight Crack is simulated in a compact tension specimen subjected to small scale yielding conditions, using the plastic Crack tip opening displacement range ( Δ CTOD p ) as the Crack driving force. The predicted Crack shape shows high agreement with experimental observations and the Crack opening load trends are consistent with the literature, demonstrating that the methodology proposed can be relevant for further Crack growth studies.

  • Effect of underloads on plasticity induced Crack Closure: a numerical analysis
    Journal of Engineering Materials and Technology, 2019
    Co-Authors: Fernando Antunes, Ricardo Branco, Luís Paiva, L.p. Borrego
    Abstract:

    The effect of underloads is mostly quantified by the averaged effect on the fatigue Crack growth rate, and the transient behavior is rarely investigated. The objective of this paper is to study the mechanisms behind the effect of underloads, periodic underloads, and underloads combined with overloads. A single underload smashes the material around the Crack tip, producing a depression on Crack flank and a local reduction of contact forces at the minimum load. The reduction of plastic elongation behind the Crack tip has an immediate effect on Crack opening level, which rapidly disappears with Crack propagation. The smashing associated with the compressive force occurs mainly behind the Crack tip position where the underload was applied. The effect of the underload is intimately linked to reversed plastic deformation, which explains its enhanced effect for kinematic hardening. The decrease of load below the minimum baseline load is the main loading parameter. The application of periodic underloads extends the effect of a single underload. The effect of the underload is enhanced by the presence of obstacles in the form of residual plastic deformation, which explains the great effect of underloads applied after overloads.

  • A new method for analysis of part-elliptical surface Cracks in structures subjected to fatigue loading
    Theoretical and Applied Fracture Mechanics, 2019
    Co-Authors: B. Zakavi, Andrei Kotousov, Aditya Khanna, Ricardo Branco
    Abstract:

    Abstract This paper presents a new analytical method for the analysis of fatigue growth of surface Cracks in various structural components. The method is based on a governing equation describing the front evolution of surface Cracks of elliptical and part-elliptical shapes. This method avoids the need for various numerical schemes for the calculation of the incremental Crack front advance, which were used in all previous studies. Plasticity-Induced Crack Closure models can also be incorporated into the method or these models can be deducted from a correlation of experimental data and the method predictions. When the plastic constraint conditions change significantly along the Crack front, the implementation of the plasticity induced Crack Closure models can significantly improve the accuracy of fatigue life predictions. The method is validated against previous theoretical and experimental studies.

  • A numerical study of the effect of single overloads on plasticity induced Crack Closure
    Theoretical and Applied Fracture Mechanics, 2017
    Co-Authors: J.b. Baptista, Fernando Antunes, Luis M. Correia, Ricardo Branco
    Abstract:

    Abstract In this work, the effect of single overloads on plasticity induced Crack Closure is studied. An elastic-plastic finite element model was developed and the Crack opening level was calculated from the contact forces along the Crack flank. The effects of the loading parameters and stress state are analysed, and the mechanisms behind Crack Closure variations are identified. An overload is a traumatic event that eliminates material’s memory relative to the load history. Crack tip blunting is the mechanism behind this memory loss, since it eliminates Crack Closure. Material hardening has a major relevance on the evolution of plastic blunting, which was evident in the variation of the CTOD parameter. On the other hand, the overload produces strong plastic deformation ahead of the Crack tip, giving rise to conditions for the rapid generation of Crack Closure higher than before the event. The peak of Crack Closure was found to increase linearly with the load increase above the maximum baseline value. The Crack is totally closed for overload ratios of about 2.5. Empirical models were developed for the peak of Crack Closure, for the delay of this peak and for the stabilization distance after the overload. Finally, the stress state was found to have a major effect on Crack Closure level after an overload.

  • A numerical analysis of the mechanisms behind plasticity induced Crack Closure: Application to variable amplitude loadings
    International Journal of Fatigue, 2016
    Co-Authors: Fernando Antunes, F.a. Castanheira, Ricardo Branco
    Abstract:

    Abstract The effect of loading parameters on fatigue Crack growth has been explained using the concept of Crack Closure. Plasticity induced Crack Closure (PICC) is linked to the Crack tip plastic deformation, which becomes residual with Crack propagation. The objective here is to identify the main mechanisms behind PICC, and for that different loading cases were considered namely overloads and load blocks. An analytical model was used to isolate the effect of residual plastic deformation on PICC, however significant differences were obtained relatively to finite element results. A second mechanism, which is Crack tip blunting, was used to explain the transient behaviour observed after overloads and load blocks. For overloads and low–high load sequences there is a sudden increase of Crack tip blunting with load increase which explains the sudden decrease of Crack opening level. For high–low load sequences there is a sudden decrease of Crack tip blunting which enhances the effect of residual plastic wake. Finally, the partial Closure concept was tested looking to non-linear Crack tip parameters but no evidences of Donald’s effect were found for the material studied.

Ian Sinclair - One of the best experts on this subject based on the ideXlab platform.

  • Variable amplitude fatigue Crack growth behavior — a short overview
    Journal of Mechanical Science and Technology, 2011
    Co-Authors: Konjengbam Darunkumar Singh, Matthew Roger Parry, Ian Sinclair
    Abstract:

    A short overview concerning variable amplitude (VA) fatigue Crack growth behavior is presented in this paper. The topics covered in this review encompass important issues pertaining to both single and repeated overload transients. Reviews on transient post overload effects such as plasticity induced Crack Closure, Crack tip blunting, residual stresses, Crack deflection and branching, activation of near threshold mechanisms, strain hardening are highlighted. A brief summary on experimental trends and finite element modelling of overload induced Crack Closure is also presented.

  • Some issues on finite element modelling of plasticity induced Crack Closure due to constant amplitude loading
    International Journal of Fatigue, 2008
    Co-Authors: Konjengbam Darunkumar Singh, Matthew Roger Parry, Ian Sinclair
    Abstract:

    An investigation of plasticity induced Crack Closure (PICC) behaviour using finite element (FE) method is presented for Cracks subjected to constant amplitude loading and small scale yielding (SSY) conditions. Undeflected Cracks have been examined under both plane strain and plane stress conditions. Anomalous near-tip Closure in FE models has been identified to occur under both plane stress and plane strain conditions and is seen to vary with baseline load levels and Crack propagation algorithms. In the case of plane strain models, propagation algorithms are seen to influence pre-Crack Closure. In general terms it may be said that none of the plane strain models showed Crack Closure that could be related to ongoing/steady-state Crack growth: Crack Closure in all cases was dominated by pre-Crack contact, and/or anomalous near-tip contact, even for the relatively long Crack propagation used in the low loading range models.

  • Roughness- and Plasticity-Induced fatigue Crack Closure under single overloads: Analytical modelling
    Acta Materialia, 2006
    Co-Authors: Konjengbam Darunkumar Singh, Kern Hauw Khor, Ian Sinclair
    Abstract:

    A simple micromechanical model for the competitive influences of roughness-induced Crack Closure (RICC) and Plasticity-Induced Crack Closure (PICC) on fatigue during single peak overloads has been developed following the approach of Kamp et al. [Kamp N, Parry MR, Singh KD, Sinclair I. Acta Mater 2004;52:343]. This is seen to be functionally comparable to the finite element results of the accompanying paper [Singh KD, Khor KH, Sinclair I. Acta Mater 2006;54:4393], and consistent with a range of experimental data. Competitive influences of PICC and RICC effects during overload transients are particularly identified here.

  • numerical modelling of combined roughness and plasticity induced Crack Closure effects in fatigue
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2000
    Co-Authors: Matthew Roger Parry, Stavros Syngellakis, Ian Sinclair
    Abstract:

    The incidence of roughness induced fatigue Crack Closure has been studied by finite element modelling. Closure analyses in the literature have been reviewed and been shown to lack a reasonable treatment of: (a) propagating elastic-plastic Cracks, and (b) the influence of the characteristically inhomogeneous plastic deformation associated with near-threshold Crack growth in many materials. Based on an analysis of both overall specimen compliance and node behaviour along the Crack path, the present modelling shows: (a) an increasing effect of Crack path angle on roughness induced Closure levels in keeping with the simple analytical model of Suresh and Ritchie; (b) the mechanism by which Closure occurs is more strongly dependent on residual plastic strains in the wake than global shear displacements of the fracture surfaces due to mixed-mode behaviour at the Crack tip; and (c) the Closure levels are relatively low compared to experimental data, consistent with the absence of environmental irreversibility in the finite element models and the idealised Crack path morphologies that were studied. Slip band simulations show a significant increasing effect of inhomogeneous deformation on Closure levels, improving the apparent accuracy of the modelling results.

  • Numerical Modelling of Roughness and Plasticity Induced Crack Closure Effects in Fatigue
    Materials Science Forum, 2000
    Co-Authors: Matthew Roger Parry, Stavros Syngellakis, Ian Sinclair
    Abstract:

    The incidence of roughness induced fatigue Crack Closure has been studied by finite element modelling. Closure analyses in the literature have been reviewed and been shown to lack a reasonable treatment of: (a) propagating elastic-plastic Cracks, and (b) the influence of the characteristically inhomogeneous plastic deformation associated with near-threshold Crack growth in many materials. Based on an analysis of both overall specimen compliance and node behaviour along the Crack path, the present modelling shows: (a) an increasing effect of Crack path angle on roughness induced Closure levels in keeping with the simple analytical model of Suresh and Ritchie; (b) the mechanism by which Closure occurs is more strongly dependent on residual plastic strains in the wake than global shear displacements of the fracture surfaces due to mixed-mode behaviour at the Crack tip; and (c) the Closure levels are relatively low compared to experimental data, consistent with the absence of environmental irreversibility in the finite element models and the idealised Crack path morphologies that were studied. Slip band simulations show a significant increasing effect of inhomogeneous deformation on Closure levels, improving the apparent accuracy of the modelling results.

D Camas - One of the best experts on this subject based on the ideXlab platform.

  • 3D numerical study of the transient behaviour on plasticity induced Crack Closure
    2019
    Co-Authors: D Camas, Pablo Lopez-crespo, Fernando Antunes, Antonio Gonzalez-herrera
    Abstract:

    Daniel Camas, Fernando Antunes, Pablo Lopez-Crespo, Antonio Gonzalez-Herrera, 3D Numerical Study of the Transient Behaviour on Plasticity Induced Crack Closure, Abstract Booklet of the MSMF9, Edited by Pavel Sandera, Brno University of Technology, 2019, pp. 136.

  • Numerical Analysis of the Influence of Crack Growth Scheme on Plasticity Induced Crack Closure Results
    Structural Integrity, 2019
    Co-Authors: D Camas, Fernando Antunes, J. Garcia-manrique, Antonio Gonzalez-herrera
    Abstract:

    Plasticity Induced Crack Closure (PICC) has been studied by means of finite element method for a long time. Most of previous work was developed considering bi-dimensional models. During last years, the use of three-dimensional models has been extended. Nevertheless, the methodology employed has been inherited from bi-dimensional analyses. Many previous bi-dimensional analyses studied different numerical parameters and optimized them. Present computational capabilities allow a comprehensive study of the influence of different modelling parameter in a similar way to those bi-dimensional analyses. Moreover, the influence of these parameters on the obtained results along the thickness can be taken into consideration. In particular, one of the key issues is related to the Crack growth scheme. A fatigue analysis implies a Crack growth. Each change in loading and boundary conditions implies solving a nonlinear problem. It is not feasible to consider all the cycles involved in a real fatigue problem when running a finite element analysis. The computational cost is not acceptable. In the present work, a CT aluminium specimen has been modelled three-dimensionally and several calculations have been made in order to evaluate the influence of the number of load cycles between node releases. The results are analysed in terms of Crack Closure and opening values.

  • Influence of plastic wake length on results of 3D numerical modelling of plasticity induced Crack Closure
    Procedia structural integrity, 2019
    Co-Authors: D Camas, F.v. Antunes, Pablo Lopez-crespo, Antonio Gonzalez-herrera
    Abstract:

    Abstract The numerical analysis of the plasticity induced Crack Closure requires the development of the plastic wake. Transient behaviour is observed when the Crack starts to grow. The plastic wake length has an influence on the Crack Closure results and a great impact on the computational cost. Previous works have analysed the influence of this parameter considering bi-dimensional specimens in either plane strain or plane stress conditions. Lately, some three-dimensional models have appeared in order to analyse the Crack Closure phenomenon. The main scope of this study is to quantify and comprehend the minimum length required to stabilise the Crack opening and Closure values considering a three-dimensional model. On this purpose, a CT aluminium specimen has been modelled three-dimensionally considering a straight Crack front and several calculations have been made in order to evaluate the influence of the simulated plastic wake. The numerical analysis is made in terms of Crack Closure and opening values.

  • Numerical analysis of the influence of the last cycle scheme on plasticity induced Crack Closure
    Procedia Structural Integrity, 2019
    Co-Authors: D Camas, Fernando Antunes, B. Moreno, Antonio Gonzalez-herrera
    Abstract:

    Abstract Plasticity induced Crack Closure is considered the main mechanism related to the premature contact of the Crack flanks when a Crack grows under cyclic loadings. This phenomenon has been studied numerically since the early 70s, when some researchers approached to metal fatigue problems by means of the finite element analysis. The numerical analysis requires the development of a plastic wake. How this plastic wake is developed has influence on the Crack Closure results and a great impact on the computational cost. When running a finite element analysis, it is not possible to consider all the loading cycles involved in an experimental test. The numerical effort is not acceptable. Therefore, in this work, the Crack growth scheme is analyzed. In particular, the influence of the number of loading cycles after releasing the last set of nodes on plasticity induced Crack Closure results is studied. A CT aluminum specimen has been modelled three-dimensionally and several simulations have been run to evaluate the influence of the loading cycles after releasing the last set of nodes. The numerical analysis is made in terms of Crack Closure and opening values.

  • Corrections in numerical methodology to evaluate plasticity induced Crack Closure along the thickness
    Theoretical and Applied Fracture Mechanics, 2018
    Co-Authors: J. Garcia-manrique, D Camas, Maria Eugenia Parron-rubio, Antonio Gonzalez-herrera
    Abstract:

    Abstract The influence of the three-dimensional effects of the distribution of the stress intensity factor in the numerical calculation of Plasticity-Induced Crack Closure is analysed in this paper. The usual methodology assumes a constant distribution of K along the thickness to obtain the effective stress intensity factor of the Crack. This assumption should not be transposed to models that intend to observe phenomena in the Crack front vicinity, where 3-D effects are a key aspect in the results. Through numerical simulations of both fracture and fatigue of through thickness straight Cracks (CT specimen in mode I), the local opening and Closure moment of each Crack node is obtained and compared with previous one. Corrections are proposed for numerical methodology to obtain Kop and Kcl distribution along the thickness.

Konjengbam Darunkumar Singh - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of plane strain plasticity induced Crack Closure effects for bimaterial interfacial Cracks
    International Journal of Fatigue, 2015
    Co-Authors: Konjengbam Darunkumar Singh, Imran Ali Khan
    Abstract:

    Abstract The effects of plane strain plasticity induced Crack Closure on fatigue Cracks located at the interface of dissimilar steel materials are presented using finite element modelling. Based on the study, it has been observed that bimaterial Cracks produced unsymmetrical residual plastic strains and Crack profiles in the Crack wakes. It is seen that Young’s modulus and yield stress mismatch have profound effects on the development of unsymmetrical residual plastic strain and Crack profiles, whereas the effect of Poisson’s ratio is insignificant. However, it has been found that for the material properties considered, low value of Crack Closure levels have been identified.

  • Variable amplitude fatigue Crack growth behavior — a short overview
    Journal of Mechanical Science and Technology, 2011
    Co-Authors: Konjengbam Darunkumar Singh, Matthew Roger Parry, Ian Sinclair
    Abstract:

    A short overview concerning variable amplitude (VA) fatigue Crack growth behavior is presented in this paper. The topics covered in this review encompass important issues pertaining to both single and repeated overload transients. Reviews on transient post overload effects such as plasticity induced Crack Closure, Crack tip blunting, residual stresses, Crack deflection and branching, activation of near threshold mechanisms, strain hardening are highlighted. A brief summary on experimental trends and finite element modelling of overload induced Crack Closure is also presented.

  • Some issues on finite element modelling of plasticity induced Crack Closure due to constant amplitude loading
    International Journal of Fatigue, 2008
    Co-Authors: Konjengbam Darunkumar Singh, Matthew Roger Parry, Ian Sinclair
    Abstract:

    An investigation of plasticity induced Crack Closure (PICC) behaviour using finite element (FE) method is presented for Cracks subjected to constant amplitude loading and small scale yielding (SSY) conditions. Undeflected Cracks have been examined under both plane strain and plane stress conditions. Anomalous near-tip Closure in FE models has been identified to occur under both plane stress and plane strain conditions and is seen to vary with baseline load levels and Crack propagation algorithms. In the case of plane strain models, propagation algorithms are seen to influence pre-Crack Closure. In general terms it may be said that none of the plane strain models showed Crack Closure that could be related to ongoing/steady-state Crack growth: Crack Closure in all cases was dominated by pre-Crack contact, and/or anomalous near-tip contact, even for the relatively long Crack propagation used in the low loading range models.

  • Roughness- and Plasticity-Induced fatigue Crack Closure under single overloads: Analytical modelling
    Acta Materialia, 2006
    Co-Authors: Konjengbam Darunkumar Singh, Kern Hauw Khor, Ian Sinclair
    Abstract:

    A simple micromechanical model for the competitive influences of roughness-induced Crack Closure (RICC) and Plasticity-Induced Crack Closure (PICC) on fatigue during single peak overloads has been developed following the approach of Kamp et al. [Kamp N, Parry MR, Singh KD, Sinclair I. Acta Mater 2004;52:343]. This is seen to be functionally comparable to the finite element results of the accompanying paper [Singh KD, Khor KH, Sinclair I. Acta Mater 2006;54:4393], and consistent with a range of experimental data. Competitive influences of PICC and RICC effects during overload transients are particularly identified here.