The Experts below are selected from a list of 7492017 Experts worldwide ranked by ideXlab platform
James A Dicarlo - One of the best experts on this subject based on the ideXlab platform.
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in plane cracking behavior and ultimate strength for 2d woven and braided melt infiltrated sic sic composites tensile loaded in off axis fiber directions
Journal of the American Ceramic Society, 2007Co-Authors: Gregory N Morscher, Hee Mann Yun, James A DicarloAbstract:The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for the architectural design of CMC components that are subjected to multiaxial stress states. In this study, two-dimensional (2D)-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0° and 90° directions were tensile loaded in-plane in the 0° direction and at 45° to this direction. In addition, a 2D triaxially braided MI SiC/SiC composite panel with a higher fiber content in the ±67° bias directions compared with the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23° from the bias fibers). Stress–strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis-loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0° direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on weak regions in the architecture, e.g., minicomposite tows oriented normal to the loading direction and/or critical flaws in the matrix for a given composite stress. Both off-axis-oriented panels also showed relatively good ultimate tensile strength when compared with other off-axis-oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial implications are discussed for constituent and architecture design to improve the directional cracking of SiC/SiC CMC components with MI matrices.
Gregory N Morscher - One of the best experts on this subject based on the ideXlab platform.
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in plane cracking behavior and ultimate strength for 2d woven and braided melt infiltrated sic sic composites tensile loaded in off axis fiber directions
Journal of the American Ceramic Society, 2007Co-Authors: Gregory N Morscher, Hee Mann Yun, James A DicarloAbstract:The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for the architectural design of CMC components that are subjected to multiaxial stress states. In this study, two-dimensional (2D)-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0° and 90° directions were tensile loaded in-plane in the 0° direction and at 45° to this direction. In addition, a 2D triaxially braided MI SiC/SiC composite panel with a higher fiber content in the ±67° bias directions compared with the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23° from the bias fibers). Stress–strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis-loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0° direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on weak regions in the architecture, e.g., minicomposite tows oriented normal to the loading direction and/or critical flaws in the matrix for a given composite stress. Both off-axis-oriented panels also showed relatively good ultimate tensile strength when compared with other off-axis-oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial implications are discussed for constituent and architecture design to improve the directional cracking of SiC/SiC CMC components with MI matrices.
A. Rezgui - One of the best experts on this subject based on the ideXlab platform.
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Directional model for isotropic hyperelastic rubber-like materials
Mechanics of Materials, 2004Co-Authors: Julie Diani, Mathias Brieu, J.m. Vacherand, A. RezguiAbstract:A material Direction-Dependent constitutive model has been formulated for large deformations for isotropic and anisotropic rubber-like materials. Although such materials are usually isotropic, anisotropic behavior has been observed in calendered plates of filled rubbers. Strain energy density function characterizing rubber-like materials is usually dependent on principal stretch ratios and thus is unable to account for anisotropy, whereas the proposed strain energy density depends on material directions and accounts for anisotropy. The material directions have simply been chosen using regular solid geometry. The strain energy density is given as the sum, over all material directions, of elementary directional strain energy densities. Then the elementary strain energy form is phenomenologically determined to account for the state of strain dependence of the material response. The model response is compared to uniaxial tension experimental data for anisotropic hyperelastic rubber-like materials and to uniaxial and biaxial tension for isotropic rubber-like materials.
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Directional model for anisotropic hyperelastic rubber-like materials
Journal of Physics IV, 2003Co-Authors: Julie Diani, Mathias Brieu, J.m. Vacherand, A. RezguiAbstract:A material Direction-Dependent constitutive model has been formulated for large deformation of anisotropic rubber-like materials. Anisotropic behavior has been observed in calendered plates of filled elastomers. Strain energy density functions characterizing rubber-like material behavior are usually dependent on the principal stretch ratios and are unable to take into account anisotropy. The proposed strain energy density depends on material directions and accounts for anisotropy. Model material directions have simply been chosen using existing macromolecular model chains geometry. The material strain energy density is given as the sum, over all material directions, of the elementary directional strain energy density. This elementary strain energy is determined by analogy with chain entropy of macromolecular models using the Langevin statistics. To evaluate the effectiveness of the proposed model, it is compared to uniaxial tension experimental data of anisotropic hyperelastic rubber-like materials.
E. J. Mittemeijer - One of the best experts on this subject based on the ideXlab platform.
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Diffraction stress analysis of grain interaction in polycrystalline materials
Zeitschrift für Kristallographie, 2006Co-Authors: U. Welzel, Sylvain Fréour, A. Kumar, E. J. MittemeijerAbstract:This work summarises recent developments of so-called Direction-Dependent elastic grain-interaction models. The notion 'Direction-Dependent' grain-interaction signifies that different grain-interaction constraints prevail along different directions in a specimen. Practical examples of Direction-Dependent grain interaction are the occurrence of surface anisotropy in thin films (and, possibly, surface regions of bulk polycrystals) and the occurrence of a grain-shape (morphological) texture.
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Direction-Dependent elastic grain-interaction models – a comparative study
Philosophical Magazine, 2005Co-Authors: U. Welzel, Sylvain Fréour, E. J. MittemeijerAbstract:Mechanical and diffraction (X-ray) elastic constants (diffraction (X-ray) stress factors for macroscopically elastically anisotropic specimens) can be calculated for polycrystalline specimens from single-crystal elastic data by employing elastic grain-interaction models. Traditionally, only so-called isotropic grain-interaction models are considered: all directions in the polycrystal are taken equivalent with respect to the grain interaction. Only recently, so-called Direction-Dependent, i.e. anisotropic grain-interaction models, have been proposed. These models can express the effects of the reduced dimensionality of thin films, of the surface anisotropy of bulk polycrystals and of a grain-shape (morphological) texture on the elastic properties of polycrystals. In this work, the available, recently proposed Direction-Dependent grain-interaction models will be compared, in particular on the basis of numerical calculations of diffraction and mechanical elastic constants, of variances of certain orientation...
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Diffraction Stress Analysis Using Direction Dependent Grain-Interaction Models
Materials Science Forum, 2005Co-Authors: U. Welzel, Sylvain Fréour, A. Kumar, E. J. MittemeijerAbstract:Recently, so-called Direction-Dependent elastic grain-interaction models have been developed, which are capable of considering the effects of surface anisotropy or of a grain-shape (morphological) texture on the mechanical elastic constants and diffraction (X-ray) stress factors of polycrystals. The notion ‘Direction-Dependent grain-interaction’ signifies that different grain interaction constraints prevail along different directions in the polycrystal. This work summarizes recent developments and presents a comparison of Direction-Dependent elastic grain-interaction models.
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Direction-Dependent Elastic Grain-Interaction Models
Philosophical Magazine, 2005Co-Authors: U. Welzel, Sylvain Fréour, E. J. MittemeijerAbstract:Mechanical and diffraction (X-ray) elastic constants (diffraction (X-ray) stress factors for macroscopically elastically anisotropic specimens) can be calculated for polycrystalline specimens from single-crystal elastic data by employing elastic grain-interaction models. Traditionally, only so-called isotropic grain-interaction models are considered: all directions in the polycrystal are taken equivalent with respect to the grain interaction. Only recently, so-called Direction-Dependent, i.e. anisotropic grain-interaction models, have been proposed. These models can express the effects of the reduced dimensionality of thin films, of the surface anisotropy of bulk polycrystals and of a grain-shape (morphological) texture on the elastic properties of polycrystals. In this work, the available, recently proposed Direction-Dependent grain-interaction models will be compared, in particular on the basis of numerical calculations of diffraction and mechanical elastic constants, of variances of certain orientation-dependent stress and strain tensor components and of the distributions of strains in the Euler (orientation) space. It will be demonstrated that the so-called Vook–Witt and inverse Vook–Witt models become (but only approximate) equivalent to the Eshelby–Kröner model for certain grain-shape textures.
Hee Mann Yun - One of the best experts on this subject based on the ideXlab platform.
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in plane cracking behavior and ultimate strength for 2d woven and braided melt infiltrated sic sic composites tensile loaded in off axis fiber directions
Journal of the American Ceramic Society, 2007Co-Authors: Gregory N Morscher, Hee Mann Yun, James A DicarloAbstract:The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for the architectural design of CMC components that are subjected to multiaxial stress states. In this study, two-dimensional (2D)-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0° and 90° directions were tensile loaded in-plane in the 0° direction and at 45° to this direction. In addition, a 2D triaxially braided MI SiC/SiC composite panel with a higher fiber content in the ±67° bias directions compared with the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23° from the bias fibers). Stress–strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis-loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0° direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on weak regions in the architecture, e.g., minicomposite tows oriented normal to the loading direction and/or critical flaws in the matrix for a given composite stress. Both off-axis-oriented panels also showed relatively good ultimate tensile strength when compared with other off-axis-oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial implications are discussed for constituent and architecture design to improve the directional cracking of SiC/SiC CMC components with MI matrices.