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Theodore E. Matikas - One of the best experts on this subject based on the ideXlab platform.

  • cyclic loading of a sic fiber reinforced Ceramic Matrix Composite reveals damage mechanisms and thermal residual stress state
    Composites Part A-applied Science and Manufacturing, 2013
    Co-Authors: Konstantinos G Dassios, Evangelos Z. Kordatos, Dimitrios G Aggelis, Theodore E. Matikas
    Abstract:

    Abstract This study reports on the effects of axial thermal residual stresses, cyclic loading and presence of notches on the tensile performance of a SiC-fiber-reinforced barium–magnesium–alumina–silicate (BMAS) Ceramic Matrix Composite. The residual stress state of the Composite was experimentally measured by interrogation of the tensile curves at a uniquely well-defined common intersection point of unloading–reloading cycles in the tensile domain. Notch presence was critical on the material’s mechanical response and promoted catastrophic failure shortly after the achievement of a saturated Matrix crack state. The result of cyclic loading was an increase by 20% in sustainable stress throughout loading, as compared to pure tension. Scatter in elastic properties within specimens of different notch-to-width ratios was reconciled with theoretical expectations by application of a translation vector approach in the stress–strain plane, based on the material’s residual stress state. Acoustic emission and infrared thermography provided valuable insight into damage identification, location and sequence.

  • Damage Assessment in a SiC-fiber reinforced Ceramic Matrix Composite
    Journal of Engineering, 2013
    Co-Authors: Konstantinos G Dassios, Theodore E. Matikas
    Abstract:

    Assessment of the fracture behavior of a SiC-fbre-reinforced barium osumilite (BMAS) Ceramic Matrix Composite tested under static and cyclic tension conditions is reported herein. Notched specimens were used in order to limit material damage within a predefined gauge length. Imposition of successive unloading/reloading loops was found to result in an increase by 20% in material strength as compared to pure tension; the observed increase is attributed to energy dissipation from large-scale interfacial debonding phenomena that dominated the post-elastic tensile behaviour of the Composite. Cyclic loading also helped establish the axial residual stress state of the fibres in the Composite of tensile nature via a well-defined common intersection point of unloading-reloading cycles. A translation vector approach in the stress-strain plane was successful in establishing the residual stress-free properties of the Composite and in reconciling the scatter noted in elastic properties of specimens with respect to theoretical expectations.

  • large scale interfacial damage and residual stresses in a glass Ceramic Matrix Composite
    Composite Interfaces, 2012
    Co-Authors: Konstantinos G Dassios, Theodore E. Matikas
    Abstract:

    The current work is concerned with the micro-mechanics of fracture of a SiC-fiber-reinforced barium osumilite (BMAS) Ceramic Matrix Composite tested under both monotonic and cyclic tension. The double-edge notch (DEN) specimen configuration was employed in order to confine material damage within a predefined gage length. The imposition of successive loops of unloading to complete load relaxation and subsequent reloading were found to result in an increase by 20% in material strength as compared to pure tension; the finding is attributed to energy dissipation from large-scale interfacial debonding phenomena that dominated the post-elastic mechanical behavior of the Composite. Cyclic loading also helped establish the axial residual stress state of the fibers in the Composite, of tensile nature, via a well-defined common intersection point of unloading–reloading cycles. An approach consisting of the application of a translation vector in the stress–strain plane was successfully used to derive the residual st...

  • Large-scale interfacial damage and residual stresses in a glass–Ceramic Matrix Composite
    Composite Interfaces, 2012
    Co-Authors: Konstantinos G Dassios, Theodore E. Matikas
    Abstract:

    The current work is concerned with the micro-mechanics of fracture of a SiC-fiber-reinforced barium osumilite (BMAS) Ceramic Matrix Composite tested under both monotonic and cyclic tension. The double-edge notch (DEN) specimen configuration was employed in order to confine material damage within a predefined gage length. The imposition of successive loops of unloading to complete load relaxation and subsequent reloading were found to result in an increase by 20% in material strength as compared to pure tension; the finding is attributed to energy dissipation from large-scale interfacial debonding phenomena that dominated the post-elastic mechanical behavior of the Composite. Cyclic loading also helped establish the axial residual stress state of the fibers in the Composite, of tensile nature, via a well-defined common intersection point of unloading–reloading cycles. An approach consisting of the application of a translation vector in the stress–strain plane was successfully used to derive the residual st...

K. N. Subramanian - One of the best experts on this subject based on the ideXlab platform.

  • Thermal expansion studies on a metallic-glass ribbon-reinforced glass-Ceramic-Matrix Composite
    Journal of Materials Science, 1994
    Co-Authors: Rajendra U. Vaidya, Krishan Kumar Chawla, K. N. Subramanian
    Abstract:

    The thermal-expansion behaviour of a metallic-glass ribbon-reinforced glass-Ceramic-Matrix Composite was studied. The coefficient of thermal expansion of such Composites measured in the longitudinal direction was correlated with the volume fraction, the length and the width of the ribbon reinforcements. The experimentally measured values of the thermal-expansion coefficients were found to be in good agreement with a modified Schapery's equation. Formation of an oxide layer on the ribbon surface and other related phenomena occurring at elevated temperatures were also found to affect the thermal expansion of such Composites, and these factors were accommodated into Schapery's equation by incorporating an empirical constant.

  • thermal expansion studies on a metallic glass ribbon reinforced glass Ceramic Matrix Composite
    Journal of Materials Science, 1994
    Co-Authors: Rajendra U. Vaidya, Krishan Kumar Chawla, K. N. Subramanian
    Abstract:

    The thermal-expansion behaviour of a metallic-glass ribbon-reinforced glass-Ceramic-Matrix Composite was studied. The coefficient of thermal expansion of such Composites measured in the longitudinal direction was correlated with the volume fraction, the length and the width of the ribbon reinforcements. The experimentally measured values of the thermal-expansion coefficients were found to be in good agreement with a modified Schapery's equation.

  • Interfacial effects in a metallic-glass ribbon reinforced glass-Ceramic Matrix Composite
    Journal of Materials Science, 1992
    Co-Authors: Rajendra U. Vaidya, C. Norris, K. N. Subramanian
    Abstract:

    The effect of temperature on the interfacial effects in a metallic-glass ribbon reinforced glass-Ceramic Matrix Composite was investigated. The metallic-glass ribbon present in this Composite was found to be significantly affected at elevated temperatures, owing to the diffusion of lead and zinc from the Matrix. The presence of the Matrix in the vicinity of the ribbon enhanced the formation of an oxide layer on the ribbon surface. The oxide layer decreased the interfacial bond strength between the ribbon and the Matrix, affecting the failure mode of such Composites at elevated temperatures.

Konstantinos G Dassios - One of the best experts on this subject based on the ideXlab platform.

  • cyclic loading of a sic fiber reinforced Ceramic Matrix Composite reveals damage mechanisms and thermal residual stress state
    Composites Part A-applied Science and Manufacturing, 2013
    Co-Authors: Konstantinos G Dassios, Evangelos Z. Kordatos, Dimitrios G Aggelis, Theodore E. Matikas
    Abstract:

    Abstract This study reports on the effects of axial thermal residual stresses, cyclic loading and presence of notches on the tensile performance of a SiC-fiber-reinforced barium–magnesium–alumina–silicate (BMAS) Ceramic Matrix Composite. The residual stress state of the Composite was experimentally measured by interrogation of the tensile curves at a uniquely well-defined common intersection point of unloading–reloading cycles in the tensile domain. Notch presence was critical on the material’s mechanical response and promoted catastrophic failure shortly after the achievement of a saturated Matrix crack state. The result of cyclic loading was an increase by 20% in sustainable stress throughout loading, as compared to pure tension. Scatter in elastic properties within specimens of different notch-to-width ratios was reconciled with theoretical expectations by application of a translation vector approach in the stress–strain plane, based on the material’s residual stress state. Acoustic emission and infrared thermography provided valuable insight into damage identification, location and sequence.

  • Damage Assessment in a SiC-fiber reinforced Ceramic Matrix Composite
    Journal of Engineering, 2013
    Co-Authors: Konstantinos G Dassios, Theodore E. Matikas
    Abstract:

    Assessment of the fracture behavior of a SiC-fbre-reinforced barium osumilite (BMAS) Ceramic Matrix Composite tested under static and cyclic tension conditions is reported herein. Notched specimens were used in order to limit material damage within a predefined gauge length. Imposition of successive unloading/reloading loops was found to result in an increase by 20% in material strength as compared to pure tension; the observed increase is attributed to energy dissipation from large-scale interfacial debonding phenomena that dominated the post-elastic tensile behaviour of the Composite. Cyclic loading also helped establish the axial residual stress state of the fibres in the Composite of tensile nature via a well-defined common intersection point of unloading-reloading cycles. A translation vector approach in the stress-strain plane was successful in establishing the residual stress-free properties of the Composite and in reconciling the scatter noted in elastic properties of specimens with respect to theoretical expectations.

  • large scale interfacial damage and residual stresses in a glass Ceramic Matrix Composite
    Composite Interfaces, 2012
    Co-Authors: Konstantinos G Dassios, Theodore E. Matikas
    Abstract:

    The current work is concerned with the micro-mechanics of fracture of a SiC-fiber-reinforced barium osumilite (BMAS) Ceramic Matrix Composite tested under both monotonic and cyclic tension. The double-edge notch (DEN) specimen configuration was employed in order to confine material damage within a predefined gage length. The imposition of successive loops of unloading to complete load relaxation and subsequent reloading were found to result in an increase by 20% in material strength as compared to pure tension; the finding is attributed to energy dissipation from large-scale interfacial debonding phenomena that dominated the post-elastic mechanical behavior of the Composite. Cyclic loading also helped establish the axial residual stress state of the fibers in the Composite, of tensile nature, via a well-defined common intersection point of unloading–reloading cycles. An approach consisting of the application of a translation vector in the stress–strain plane was successfully used to derive the residual st...

  • Large-scale interfacial damage and residual stresses in a glass–Ceramic Matrix Composite
    Composite Interfaces, 2012
    Co-Authors: Konstantinos G Dassios, Theodore E. Matikas
    Abstract:

    The current work is concerned with the micro-mechanics of fracture of a SiC-fiber-reinforced barium osumilite (BMAS) Ceramic Matrix Composite tested under both monotonic and cyclic tension. The double-edge notch (DEN) specimen configuration was employed in order to confine material damage within a predefined gage length. The imposition of successive loops of unloading to complete load relaxation and subsequent reloading were found to result in an increase by 20% in material strength as compared to pure tension; the finding is attributed to energy dissipation from large-scale interfacial debonding phenomena that dominated the post-elastic mechanical behavior of the Composite. Cyclic loading also helped establish the axial residual stress state of the fibers in the Composite, of tensile nature, via a well-defined common intersection point of unloading–reloading cycles. An approach consisting of the application of a translation vector in the stress–strain plane was successfully used to derive the residual st...

Xingsi Han - One of the best experts on this subject based on the ideXlab platform.

  • numerical method for the thermal analysis of a Ceramic Matrix Composite turbine vane considering the spatial variation of the anisotropic thermal conductivity
    Applied Thermal Engineering, 2017
    Co-Authors: Junkui Mao, Hua Jiang, Xingsi Han
    Abstract:

    Abstract A numerical method for the thermal analysis of Ceramic Matrix Composite (CMC) turbine vane was developed considering the Anisotropic Thermal Conductivity (ATC) and its spatial variation due to the vane’s curved surface. A turbine vane with a cooling configuration was used as an example of the simulations; 3 different cases (Isotropic Thermal Conductivity (ITC), constant ATC, and ATC with spatial variation) were examined using the Finite Element Method (FEM). The effects of the thermal conductivity and its variation on the temperature distribution of the CMC turbine vane were also discussed. The results showed that the ATC changed the heat transfer rates in different directions inside the turbine vane, leading to a non-uniform temperature distribution. The ATC’s spatial variation due to the vane’s curved surface led to additional changes in the temperature distribution, especially the location of the maximum temperature and the high-temperature region. With increasing the anisotropy level, a more significant difference between the temperature fields could be observed, regardless of whether the spatial variation of the ATC was considered. The largest difference between the maximum temperatures was found to be around 107.7 K, when the ratio of the thermal conductivities in different directions was 20. The work indicates that the ATC’s spatial variation should be considered in the thermal analysis of a Composite hot component with a complex curved surface (such as a nozzle vane or turbine blade). The present numerical method developed for the thermal analysis, which considers the ATC’s spatial variation, is of reasonable applicability and accuracy.

Rajendra U. Vaidya - One of the best experts on this subject based on the ideXlab platform.

  • Thermal expansion studies on a metallic-glass ribbon-reinforced glass-Ceramic-Matrix Composite
    Journal of Materials Science, 1994
    Co-Authors: Rajendra U. Vaidya, Krishan Kumar Chawla, K. N. Subramanian
    Abstract:

    The thermal-expansion behaviour of a metallic-glass ribbon-reinforced glass-Ceramic-Matrix Composite was studied. The coefficient of thermal expansion of such Composites measured in the longitudinal direction was correlated with the volume fraction, the length and the width of the ribbon reinforcements. The experimentally measured values of the thermal-expansion coefficients were found to be in good agreement with a modified Schapery's equation. Formation of an oxide layer on the ribbon surface and other related phenomena occurring at elevated temperatures were also found to affect the thermal expansion of such Composites, and these factors were accommodated into Schapery's equation by incorporating an empirical constant.

  • thermal expansion studies on a metallic glass ribbon reinforced glass Ceramic Matrix Composite
    Journal of Materials Science, 1994
    Co-Authors: Rajendra U. Vaidya, Krishan Kumar Chawla, K. N. Subramanian
    Abstract:

    The thermal-expansion behaviour of a metallic-glass ribbon-reinforced glass-Ceramic-Matrix Composite was studied. The coefficient of thermal expansion of such Composites measured in the longitudinal direction was correlated with the volume fraction, the length and the width of the ribbon reinforcements. The experimentally measured values of the thermal-expansion coefficients were found to be in good agreement with a modified Schapery's equation.

  • Interfacial effects in a metallic-glass ribbon reinforced glass-Ceramic Matrix Composite
    Journal of Materials Science, 1992
    Co-Authors: Rajendra U. Vaidya, C. Norris, K. N. Subramanian
    Abstract:

    The effect of temperature on the interfacial effects in a metallic-glass ribbon reinforced glass-Ceramic Matrix Composite was investigated. The metallic-glass ribbon present in this Composite was found to be significantly affected at elevated temperatures, owing to the diffusion of lead and zinc from the Matrix. The presence of the Matrix in the vicinity of the ribbon enhanced the formation of an oxide layer on the ribbon surface. The oxide layer decreased the interfacial bond strength between the ribbon and the Matrix, affecting the failure mode of such Composites at elevated temperatures.