The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform

T. James Marrow - One of the best experts on this subject based on the ideXlab platform.

  • observation and simulation of indentation damage in a sic sicfibre ceramic matrix composite
    Finite Elements in Analysis and Design, 2016
    Co-Authors: Luis Saucedomora, R C Atwood, Danial Khoshkhou, Mahmoud Mostafavi, Christina Reinhard, Brian J. Connolly, Shuang Zhao, T. James Marrow
    Abstract:

    FEMME, a multi-scale Finite Element Microstructure MEshfree fracture model has been applied to simulate the effect of microstructure on the development of discontinuous cracking and damage coalescence during the Hertzian indentation of a SiC-SiC fibre composite. This was studied experimentally by digital volume correlation analysis of high-resolution synchrotron X-ray computed tomographs, which quantified the damage via measurement of the 3D displacement fields within the Material. The experimental data are compared with the model simulations, and demonstrate the applicability of the modelling strategy to simulate damage development in a heterogeneous Quasi-Brittle Material. The paper shows the influence of the microstructure in the Material.The interaction between the fibres and the pores is reproduced successfully.In the Material, the inhomogeneous strain and displacement fields are reproduced.

  • three dimensional crack observation quantification and simulation in a quasi brittle Material
    Acta Materialia, 2013
    Co-Authors: Mahmoud Mostafavi, Nikolaos Baimpas, R C Atwood, Edmund Tarleton, S A Mcdonald, Alexander M Korsunsky, T. James Marrow
    Abstract:

    Abstract To investigate the fracture behaviour of polygranular graphite (a Quasi-Brittle Material), crack propagation in a short bar chevron notched specimen was studied by synchrotron X-ray computed tomography combined with digital volume correlation. Displacements were measured within the loaded test specimen, particularly the three-dimensional (3-D) profile of crack opening displacement. Analysis of the 3-D displacement field confirmed the existence of distributed damage in a fracture process zone, which significantly increased the effective crack length. Finite element simulations affirmed that the measured crack opening profiles could be reproduced using a cohesive zone model, but not with a linear elastic analysis. Comparing the simulation to the experimental results, it was deduced that the critical strain energy release rate varied across the crack front, i.e. the fracture toughness is constraint-dependent. This is proposed to be a general characteristic of Quasi-Brittle Materials.

Mahmoud Mostafavi - One of the best experts on this subject based on the ideXlab platform.

  • observation and simulation of indentation damage in a sic sicfibre ceramic matrix composite
    Finite Elements in Analysis and Design, 2016
    Co-Authors: Luis Saucedomora, R C Atwood, Danial Khoshkhou, Mahmoud Mostafavi, Christina Reinhard, Brian J. Connolly, Shuang Zhao, T. James Marrow
    Abstract:

    FEMME, a multi-scale Finite Element Microstructure MEshfree fracture model has been applied to simulate the effect of microstructure on the development of discontinuous cracking and damage coalescence during the Hertzian indentation of a SiC-SiC fibre composite. This was studied experimentally by digital volume correlation analysis of high-resolution synchrotron X-ray computed tomographs, which quantified the damage via measurement of the 3D displacement fields within the Material. The experimental data are compared with the model simulations, and demonstrate the applicability of the modelling strategy to simulate damage development in a heterogeneous Quasi-Brittle Material. The paper shows the influence of the microstructure in the Material.The interaction between the fibres and the pores is reproduced successfully.In the Material, the inhomogeneous strain and displacement fields are reproduced.

  • three dimensional crack observation quantification and simulation in a quasi brittle Material
    Acta Materialia, 2013
    Co-Authors: Mahmoud Mostafavi, Nikolaos Baimpas, R C Atwood, Edmund Tarleton, S A Mcdonald, Alexander M Korsunsky, T. James Marrow
    Abstract:

    Abstract To investigate the fracture behaviour of polygranular graphite (a Quasi-Brittle Material), crack propagation in a short bar chevron notched specimen was studied by synchrotron X-ray computed tomography combined with digital volume correlation. Displacements were measured within the loaded test specimen, particularly the three-dimensional (3-D) profile of crack opening displacement. Analysis of the 3-D displacement field confirmed the existence of distributed damage in a fracture process zone, which significantly increased the effective crack length. Finite element simulations affirmed that the measured crack opening profiles could be reproduced using a cohesive zone model, but not with a linear elastic analysis. Comparing the simulation to the experimental results, it was deduced that the critical strain energy release rate varied across the crack front, i.e. the fracture toughness is constraint-dependent. This is proposed to be a general characteristic of Quasi-Brittle Materials.

Alberto Carpinteri - One of the best experts on this subject based on the ideXlab platform.

  • critical defect size distributions in concrete structures detected by the acoustic emission technique
    Meccanica, 2008
    Co-Authors: Alberto Carpinteri, Giuseppe Lacidogna, Gianni Niccolini, Simone Puzzi
    Abstract:

    Extensive research and studies on con- crete fracture and failure have shown that concrete should be viewed as a Quasi-Brittle Material having a size-dependent behavior. Numerous experimental techniques have been employed to evaluate fracture processes, and a number of modeling approaches have been developed to predict fracture behavior. A non- destructive method based on the Acoustic Emission (AE) technique has proved to be highly effective, es- pecially to assess and measure the damage phenomena taking place inside a structure subjected to mechani- cal loading. In this paper, comparing AE frequency- magnitude statistics in solids subjected to damage processes with defect size distributions for disordered Materials, critical parameters defining instability con- ditions for monitored structures are found. In addition, an experimental investigation conducted on concrete and RC structures by means of the AE technique is described. Experimental results confirm the described theories.

  • critical behaviour in concrete structures and damage localization by acoustic emission
    Key Engineering Materials, 2006
    Co-Authors: Alberto Carpinteri, Giuseppe Lacidogna, Gianni Niccolini
    Abstract:

    Extensive research and studies on concrete fracture and failure have shown that concrete should be viewed as a Quasi-Brittle Material having a size-dependent behaviour. Numerous experimental techniques have been employed to evaluate fracture processes, and a number of modelling approaches have been developed to predict fracture behaviour. The non-destructive method based on the Acoustic Emission (AE) technique has proved highly effective, especially to check and measure the damage phenomena that take place inside a structure subjected to mechanical loading. In this paper an experimental investigation conducted on concrete and RC structures by means of the AE technique is described. The AE signals reflecting the release of energy taking place during the damage process were recorded and micro-cracking sources were localised by measuring time delays by means of spatially distributed AE sensors.

  • cohesive crack model description of ductile to brittle size scale transition dimensional analysis vs renormalization group theory
    Engineering Fracture Mechanics, 2003
    Co-Authors: Alberto Carpinteri, Pietro Cornetti, Fabrizio Barpi, Silvio Valente
    Abstract:

    The present paper is a review of the research works carried out on the cohesive crack model and its applications at the Politecnico di Torino during the last decade. The topic encompasses experimental, numerical and theoretical aspects of the cohesive crack model. The research work followed two main directions. The earlywork concerns the development and the implementation of the cohesive crack model, which has been shown to be able to simulate experiments on concrete specimens and structures. It is referred to as the dimensional analysis approach, since it succeeds in capturing the ductile-to-brittle transition by increasing the structural size owing to the different physical dimensions of two Material parameters: the tensile strength and the fracture energy. On the other hand, the later research direction aims at extending the classical cohesive model to Quasi-Brittle Materials showing (as they often do) fractal patterns in the failure process. This approach is referred to as the renormalization group (or fractal) approach and leads to a scale-invariant cohesive crack model. This model is able to predict the size effects even in tests where the classical approach fails, e.g. the direct tension test. The two research paths, therefore, complete each other, allowing a deeper insight into the ductile-to-brittle transition usually detected when testing Quasi-Brittle Material specimens or structures at different size-scales. � 2003 Elsevier Science Ltd. All rights reserved.

Simone Puzzi - One of the best experts on this subject based on the ideXlab platform.

  • critical defect size distributions in concrete structures detected by the acoustic emission technique
    Meccanica, 2008
    Co-Authors: Alberto Carpinteri, Giuseppe Lacidogna, Gianni Niccolini, Simone Puzzi
    Abstract:

    Extensive research and studies on con- crete fracture and failure have shown that concrete should be viewed as a Quasi-Brittle Material having a size-dependent behavior. Numerous experimental techniques have been employed to evaluate fracture processes, and a number of modeling approaches have been developed to predict fracture behavior. A non- destructive method based on the Acoustic Emission (AE) technique has proved to be highly effective, es- pecially to assess and measure the damage phenomena taking place inside a structure subjected to mechani- cal loading. In this paper, comparing AE frequency- magnitude statistics in solids subjected to damage processes with defect size distributions for disordered Materials, critical parameters defining instability con- ditions for monitored structures are found. In addition, an experimental investigation conducted on concrete and RC structures by means of the AE technique is described. Experimental results confirm the described theories.

R C Atwood - One of the best experts on this subject based on the ideXlab platform.

  • observation and simulation of indentation damage in a sic sicfibre ceramic matrix composite
    Finite Elements in Analysis and Design, 2016
    Co-Authors: Luis Saucedomora, R C Atwood, Danial Khoshkhou, Mahmoud Mostafavi, Christina Reinhard, Brian J. Connolly, Shuang Zhao, T. James Marrow
    Abstract:

    FEMME, a multi-scale Finite Element Microstructure MEshfree fracture model has been applied to simulate the effect of microstructure on the development of discontinuous cracking and damage coalescence during the Hertzian indentation of a SiC-SiC fibre composite. This was studied experimentally by digital volume correlation analysis of high-resolution synchrotron X-ray computed tomographs, which quantified the damage via measurement of the 3D displacement fields within the Material. The experimental data are compared with the model simulations, and demonstrate the applicability of the modelling strategy to simulate damage development in a heterogeneous Quasi-Brittle Material. The paper shows the influence of the microstructure in the Material.The interaction between the fibres and the pores is reproduced successfully.In the Material, the inhomogeneous strain and displacement fields are reproduced.

  • three dimensional crack observation quantification and simulation in a quasi brittle Material
    Acta Materialia, 2013
    Co-Authors: Mahmoud Mostafavi, Nikolaos Baimpas, R C Atwood, Edmund Tarleton, S A Mcdonald, Alexander M Korsunsky, T. James Marrow
    Abstract:

    Abstract To investigate the fracture behaviour of polygranular graphite (a Quasi-Brittle Material), crack propagation in a short bar chevron notched specimen was studied by synchrotron X-ray computed tomography combined with digital volume correlation. Displacements were measured within the loaded test specimen, particularly the three-dimensional (3-D) profile of crack opening displacement. Analysis of the 3-D displacement field confirmed the existence of distributed damage in a fracture process zone, which significantly increased the effective crack length. Finite element simulations affirmed that the measured crack opening profiles could be reproduced using a cohesive zone model, but not with a linear elastic analysis. Comparing the simulation to the experimental results, it was deduced that the critical strain energy release rate varied across the crack front, i.e. the fracture toughness is constraint-dependent. This is proposed to be a general characteristic of Quasi-Brittle Materials.