The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
R Moini - One of the best experts on this subject based on the ideXlab platform.
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analysis technique for interaction of rectangular open ended waveguides with Surface cracks of arbitrary shape in metals
Ndt & E International, 2003Co-Authors: F Mazlumi, S H H Sadeghi, R MoiniAbstract:Abstract The use of microwave technique has proved to be a viable means for crack detection and Sizing Surface cracks in metals. In this technique, the Surface of the specimen is interrogated with a radiating open-ended waveguide probe and a crack is assumed to be a simple short-circuited rectangular waveguide, causing peturbations in the probe reflection coefficient. Since the growth of fatigue in metals is a stochastic process, the cracks do not have a constant predetermined shape. We describe a new formulation to model the problem of an open-ended waveguide probe radiating into a conducting metal with a Surface-breaking crack of arbitrary shape. In this formulation, the crack is first modeled by an appropriate number of short rectangular waveguides. The generalized scattering matrix technique is then used to calculate the scattering matrix of the new segmented waveguide structure. The probe reflection coefficient of the dominant mode, TE10, is finally calculated for various positions of the crack in order to predict the probe output signal. To demonstrate the accuracy of the model, we consider two special cases of a long and an elliptical-shape cracks. The comparison of our results with those available in the literature substantiates the model introduced in this paper. To further validate the model, we present results associated with a fatigue crack of complex geometry which are compared with those obtained using a finite element code.
Lawrence T Drzal - One of the best experts on this subject based on the ideXlab platform.
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glass fibre Sizing matrix interphase formation in liquid composite moulding effects on fibre matrix adhesion and mechanical properties
Composites, 1994Co-Authors: Brent Kevin Larson, Lawrence T DrzalAbstract:Abstract The glass fibre Sizing/matrix interactions in a liquid composite moulding environment have been investigated to develop an understanding of the effect of wetting between sized fibre Surfaces and the reacting liquid matrix, the structure of the resulting interphase and its effect on fibre/matrix adhesion and composite properties. The overall research objectives in this programme are to develop an experimental protocol for measurement of the key wetting parameters of the fibre and matrix; to quantify the effect of wetting on the mechanical properties of the composites formed by liquid composite moulding; and to formulate a time-, temperature- and geometry-dependent model of the liquid composite moulding process which incorporates the Surface properties of the fibre, its finish and the reactive polymer matrix. Results are presented for a series of sized glass fibres consisting of incompatible and compatible Sizings, studied with a reacting vinyl ester matrix system. Surface free energy analysis was conducted to characterize the fibre Surfaces. Axial and transverse wicking rates were measured to quantify the change in total Surface free energy of the fibre/matrix systems. The Sizing Surface free energy and its solubility in the matrix strongly affected the fibre/matrix interphase formation and consequently the fibre/matrix adhesion and composite shear and flexural strengths.
F Mazlumi - One of the best experts on this subject based on the ideXlab platform.
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analysis technique for interaction of rectangular open ended waveguides with Surface cracks of arbitrary shape in metals
Ndt & E International, 2003Co-Authors: F Mazlumi, S H H Sadeghi, R MoiniAbstract:Abstract The use of microwave technique has proved to be a viable means for crack detection and Sizing Surface cracks in metals. In this technique, the Surface of the specimen is interrogated with a radiating open-ended waveguide probe and a crack is assumed to be a simple short-circuited rectangular waveguide, causing peturbations in the probe reflection coefficient. Since the growth of fatigue in metals is a stochastic process, the cracks do not have a constant predetermined shape. We describe a new formulation to model the problem of an open-ended waveguide probe radiating into a conducting metal with a Surface-breaking crack of arbitrary shape. In this formulation, the crack is first modeled by an appropriate number of short rectangular waveguides. The generalized scattering matrix technique is then used to calculate the scattering matrix of the new segmented waveguide structure. The probe reflection coefficient of the dominant mode, TE10, is finally calculated for various positions of the crack in order to predict the probe output signal. To demonstrate the accuracy of the model, we consider two special cases of a long and an elliptical-shape cracks. The comparison of our results with those available in the literature substantiates the model introduced in this paper. To further validate the model, we present results associated with a fatigue crack of complex geometry which are compared with those obtained using a finite element code.
Brent Kevin Larson - One of the best experts on this subject based on the ideXlab platform.
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glass fibre Sizing matrix interphase formation in liquid composite moulding effects on fibre matrix adhesion and mechanical properties
Composites, 1994Co-Authors: Brent Kevin Larson, Lawrence T DrzalAbstract:Abstract The glass fibre Sizing/matrix interactions in a liquid composite moulding environment have been investigated to develop an understanding of the effect of wetting between sized fibre Surfaces and the reacting liquid matrix, the structure of the resulting interphase and its effect on fibre/matrix adhesion and composite properties. The overall research objectives in this programme are to develop an experimental protocol for measurement of the key wetting parameters of the fibre and matrix; to quantify the effect of wetting on the mechanical properties of the composites formed by liquid composite moulding; and to formulate a time-, temperature- and geometry-dependent model of the liquid composite moulding process which incorporates the Surface properties of the fibre, its finish and the reactive polymer matrix. Results are presented for a series of sized glass fibres consisting of incompatible and compatible Sizings, studied with a reacting vinyl ester matrix system. Surface free energy analysis was conducted to characterize the fibre Surfaces. Axial and transverse wicking rates were measured to quantify the change in total Surface free energy of the fibre/matrix systems. The Sizing Surface free energy and its solubility in the matrix strongly affected the fibre/matrix interphase formation and consequently the fibre/matrix adhesion and composite shear and flexural strengths.
S H H Sadeghi - One of the best experts on this subject based on the ideXlab platform.
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analysis technique for interaction of rectangular open ended waveguides with Surface cracks of arbitrary shape in metals
Ndt & E International, 2003Co-Authors: F Mazlumi, S H H Sadeghi, R MoiniAbstract:Abstract The use of microwave technique has proved to be a viable means for crack detection and Sizing Surface cracks in metals. In this technique, the Surface of the specimen is interrogated with a radiating open-ended waveguide probe and a crack is assumed to be a simple short-circuited rectangular waveguide, causing peturbations in the probe reflection coefficient. Since the growth of fatigue in metals is a stochastic process, the cracks do not have a constant predetermined shape. We describe a new formulation to model the problem of an open-ended waveguide probe radiating into a conducting metal with a Surface-breaking crack of arbitrary shape. In this formulation, the crack is first modeled by an appropriate number of short rectangular waveguides. The generalized scattering matrix technique is then used to calculate the scattering matrix of the new segmented waveguide structure. The probe reflection coefficient of the dominant mode, TE10, is finally calculated for various positions of the crack in order to predict the probe output signal. To demonstrate the accuracy of the model, we consider two special cases of a long and an elliptical-shape cracks. The comparison of our results with those available in the literature substantiates the model introduced in this paper. To further validate the model, we present results associated with a fatigue crack of complex geometry which are compared with those obtained using a finite element code.