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William L. Peirson - One of the best experts on this subject based on the ideXlab platform.
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Tangential Stress beneath wind-driven air–water interfaces
Journal of Fluid Mechanics, 1998Co-Authors: Michael L. Banner, William L. PeirsonAbstract:The detailed structure of the aqueous surface sublayer flow immediately adjacent to the wind-driven air-water interface is investigated in a laboratory wind-wave flume using particle image velocimetry (PIV) techniques. The goal is to investigate quantitatively the character of the flow in this crucial, very thin region which is often disrupted by microscale breaking events. In this study, we also examine critically the conclusions of Okuda, Kawai & Toba (1977), who argued that for very short, strongly forced wind-wave conditions, shear Stress is the dominant mechanism for transmitting the atmospheric wind Stress into the water motion - waves and surface drift currents. In strong contrast, other authors have more recently observed very substantial normal Stress contributions on the air side. The availability of PIV and associated image technology now permits a timely re-examination of the results of Okuda et al., which have been influential in shaping present perceptions of the physics of this dynamically important region. The PIV technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements, and allows reliable determination of the fluid velocity and shear within 200 μm of the instantaneous wind-driven air-water interface. The results obtained in this study are not in accord with the conclusions of Okuda et al. that the Tangential Stress component dominates the wind Stress. It is found that prior to the formation of wind waves, the Tangential Stress contributes the entire wind Stress, as expected. With increasing distance downwind, the mean Tangential Stress level decreases marginally, but as the wave field develops, the total wind Stress increases significantly. Thus, the wave form drag, represented by the difference between the total wind Stress and the mean Tangential Stress, also increases systematically with wave development and provides the major proportion of the wind Stress once the waves have developed beyond their early growth stage. This scenario reconciles the question of relative importance of normal and Tangential Stresses at an air-water interface. Finally, consideration is given to the extrapolation of these detailed laboratory results to the field, where the present findings suggest that the sea surface is unlikely to become fully aerodynamically rough, at least for moderate to strong winds.
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Tangential Stress beneath wind driven air water interfaces
Journal of Fluid Mechanics, 1998Co-Authors: Michael L. Banner, William L. PeirsonAbstract:The detailed structure of the aqueous surface sublayer flow immediately adjacent to the wind-driven air-water interface is investigated in a laboratory wind-wave flume using particle image velocimetry (PIV) techniques. The goal is to investigate quantitatively the character of the flow in this crucial, very thin region which is often disrupted by microscale breaking events. In this study, we also examine critically the conclusions of Okuda, Kawai & Toba (1977), who argued that for very short, strongly forced wind-wave conditions, shear Stress is the dominant mechanism for transmitting the atmospheric wind Stress into the water motion - waves and surface drift currents. In strong contrast, other authors have more recently observed very substantial normal Stress contributions on the air side. The availability of PIV and associated image technology now permits a timely re-examination of the results of Okuda et al., which have been influential in shaping present perceptions of the physics of this dynamically important region. The PIV technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements, and allows reliable determination of the fluid velocity and shear within 200 μm of the instantaneous wind-driven air-water interface. The results obtained in this study are not in accord with the conclusions of Okuda et al. that the Tangential Stress component dominates the wind Stress. It is found that prior to the formation of wind waves, the Tangential Stress contributes the entire wind Stress, as expected. With increasing distance downwind, the mean Tangential Stress level decreases marginally, but as the wave field develops, the total wind Stress increases significantly. Thus, the wave form drag, represented by the difference between the total wind Stress and the mean Tangential Stress, also increases systematically with wave development and provides the major proportion of the wind Stress once the waves have developed beyond their early growth stage. This scenario reconciles the question of relative importance of normal and Tangential Stresses at an air-water interface. Finally, consideration is given to the extrapolation of these detailed laboratory results to the field, where the present findings suggest that the sea surface is unlikely to become fully aerodynamically rough, at least for moderate to strong winds.
Mirmilad Mirsayar - One of the best experts on this subject based on the ideXlab platform.
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modified maximum Tangential Stress criterion for fracture behavior of zirconia veneer interfaces
Journal of The Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Mirmilad Mirsayar, Philip ParkAbstract:The veneering porcelain sintered on zirconia is widely used in dental prostheses, but repeated mechanical loadings may cause a fracture such as edge chipping or delamination. In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bi-layered components subjected to mixed mode loadings, the accuracy of a new and traditional fracture criteria are investigated. A modified maximum Tangential Stress criterion considering the effect of T-Stress and critical distance theory is introduced, and compared to three traditional fracture criteria. Comparisons to the recently published fracture test data show that the traditional fracture criteria are not able to properly predict the fracture initiation conditions in zirconia/veneer bi-material joints. The modified maximum Tangential Stress criterion provides more accurate predictions of the experimental results than the traditional fracture criteria.
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Modified maximum Tangential Stress criterion for fracture behavior of zirconia/veneer interfaces.
Journal of the Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Mirmilad Mirsayar, Philip ParkAbstract:The veneering porcelain sintered on zirconia is widely used in dental prostheses, but repeated mechanical loadings may cause a fracture such as edge chipping or delamination. In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bi-layered components subjected to mixed mode loadings, the accuracy of a new and traditional fracture criteria are investigated. A modified maximum Tangential Stress criterion considering the effect of T-Stress and critical distance theory is introduced, and compared to three traditional fracture criteria. Comparisons to the recently published fracture test data show that the traditional fracture criteria are not able to properly predict the fracture initiation conditions in zirconia/veneer bi-material joints. The modified maximum Tangential Stress criterion provides more accurate predictions of the experimental results than the traditional fracture criteria.
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The role of T-Stress on kinking angle of interface cracks
Materials & Design, 2015Co-Authors: Mirmilad Mirsayar, Philip ParkAbstract:Abstract A modified version of the maximum Tangential Stress criterion is applied to predict the kinking angle of mixed mode interface cracks existing between two dissimilar isotropic elastic solids. The presence of a crack at the bi-material interface significantly affects on mechanical strength, and may eventually result in fracture. For interfaces with strong bonding, cracks may kink into one of the materials instead of growing through the interfaces. While the traditional maximum Tangential Stress criterion uses only the Stress intensity factors in mode I and mode II, the modified criterion takes into account the effect of T-Stress as well as the Stress intensity factors. Theoretical derivation of the criterion with T-Stress is introduced, and the kinking angles are calculated by both the traditional and modified criteria. The calculated kinking angles are compared to the experimental results for interface cracks reported in three previously published papers. The comparisons show that the modified criterion is capable of successfully predicting the kinking angles with a higher accuracy than previously suggested criteria as well as the traditional maximum Tangential Stress criterion.
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on fracture of kinked interface cracks the role of t Stress
Materials & Design, 2014Co-Authors: Mirmilad MirsayarAbstract:Abstract This paper presents a modified maximum Tangential Stress criterion (MMTS) for prediction of the fracture initiation conditions in kinked bi-material cracks. The criterion takes into account the effect of T -Stress as well as the Stress intensity factors ( K I and K II ) to predict the mixed mode fracture toughness of interface cracked specimens. First the fracture criterion is developed and the effect of sign and magnitude of T -Stress on mixed mode fracture toughness is studied analytically. Then, the suggested criterion is evaluated using the experimental data reported for some epoxy/Aluminum Brazil-nut-sandwich specimens in the literature. The MMTS criterion is also compared with the conventional maximum Tangential Stress (MTS) criterion and hence, significantly improved estimates were achieved for mixed mode fracture toughness of the tested specimens.
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A modified maximum Tangential Stress criterion for determination of the fracture toughness in bi-material notches – Part 1: Theory
Engineering Solid Mechanics, 2014Co-Authors: Mirmilad MirsayarAbstract:Article history: Received June 6, 2014 Accepted 2 August 2014 Available online 4 August 2014 The effect of first nonsingular Stress term of elastic Stress field on fracture toughness around bimaterial notch tip is studies in this paper. First, a modified maximum Tangential Stress criterion (MMTS) is proposed for determination of the fracture toughness at the tip of the interface notches. The proposed criterion takes into account the effect of first nonsingular Stress term as well as the singular Stress terms. Then, the effect of I-Stress on determination of the fracture toughness is studied analytically. Finally, the proposed criterion is applied on a finite element (FE) simulated laboratory specimen. A very good correlation was observed between the FE results and theoretical predictions. © 2014 Growing Science Ltd. All rights reserved.
Michael L. Banner - One of the best experts on this subject based on the ideXlab platform.
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Tangential Stress beneath wind-driven air–water interfaces
Journal of Fluid Mechanics, 1998Co-Authors: Michael L. Banner, William L. PeirsonAbstract:The detailed structure of the aqueous surface sublayer flow immediately adjacent to the wind-driven air-water interface is investigated in a laboratory wind-wave flume using particle image velocimetry (PIV) techniques. The goal is to investigate quantitatively the character of the flow in this crucial, very thin region which is often disrupted by microscale breaking events. In this study, we also examine critically the conclusions of Okuda, Kawai & Toba (1977), who argued that for very short, strongly forced wind-wave conditions, shear Stress is the dominant mechanism for transmitting the atmospheric wind Stress into the water motion - waves and surface drift currents. In strong contrast, other authors have more recently observed very substantial normal Stress contributions on the air side. The availability of PIV and associated image technology now permits a timely re-examination of the results of Okuda et al., which have been influential in shaping present perceptions of the physics of this dynamically important region. The PIV technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements, and allows reliable determination of the fluid velocity and shear within 200 μm of the instantaneous wind-driven air-water interface. The results obtained in this study are not in accord with the conclusions of Okuda et al. that the Tangential Stress component dominates the wind Stress. It is found that prior to the formation of wind waves, the Tangential Stress contributes the entire wind Stress, as expected. With increasing distance downwind, the mean Tangential Stress level decreases marginally, but as the wave field develops, the total wind Stress increases significantly. Thus, the wave form drag, represented by the difference between the total wind Stress and the mean Tangential Stress, also increases systematically with wave development and provides the major proportion of the wind Stress once the waves have developed beyond their early growth stage. This scenario reconciles the question of relative importance of normal and Tangential Stresses at an air-water interface. Finally, consideration is given to the extrapolation of these detailed laboratory results to the field, where the present findings suggest that the sea surface is unlikely to become fully aerodynamically rough, at least for moderate to strong winds.
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Tangential Stress beneath wind driven air water interfaces
Journal of Fluid Mechanics, 1998Co-Authors: Michael L. Banner, William L. PeirsonAbstract:The detailed structure of the aqueous surface sublayer flow immediately adjacent to the wind-driven air-water interface is investigated in a laboratory wind-wave flume using particle image velocimetry (PIV) techniques. The goal is to investigate quantitatively the character of the flow in this crucial, very thin region which is often disrupted by microscale breaking events. In this study, we also examine critically the conclusions of Okuda, Kawai & Toba (1977), who argued that for very short, strongly forced wind-wave conditions, shear Stress is the dominant mechanism for transmitting the atmospheric wind Stress into the water motion - waves and surface drift currents. In strong contrast, other authors have more recently observed very substantial normal Stress contributions on the air side. The availability of PIV and associated image technology now permits a timely re-examination of the results of Okuda et al., which have been influential in shaping present perceptions of the physics of this dynamically important region. The PIV technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements, and allows reliable determination of the fluid velocity and shear within 200 μm of the instantaneous wind-driven air-water interface. The results obtained in this study are not in accord with the conclusions of Okuda et al. that the Tangential Stress component dominates the wind Stress. It is found that prior to the formation of wind waves, the Tangential Stress contributes the entire wind Stress, as expected. With increasing distance downwind, the mean Tangential Stress level decreases marginally, but as the wave field develops, the total wind Stress increases significantly. Thus, the wave form drag, represented by the difference between the total wind Stress and the mean Tangential Stress, also increases systematically with wave development and provides the major proportion of the wind Stress once the waves have developed beyond their early growth stage. This scenario reconciles the question of relative importance of normal and Tangential Stresses at an air-water interface. Finally, consideration is given to the extrapolation of these detailed laboratory results to the field, where the present findings suggest that the sea surface is unlikely to become fully aerodynamically rough, at least for moderate to strong winds.
Philip Park - One of the best experts on this subject based on the ideXlab platform.
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modified maximum Tangential Stress criterion for fracture behavior of zirconia veneer interfaces
Journal of The Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Mirmilad Mirsayar, Philip ParkAbstract:The veneering porcelain sintered on zirconia is widely used in dental prostheses, but repeated mechanical loadings may cause a fracture such as edge chipping or delamination. In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bi-layered components subjected to mixed mode loadings, the accuracy of a new and traditional fracture criteria are investigated. A modified maximum Tangential Stress criterion considering the effect of T-Stress and critical distance theory is introduced, and compared to three traditional fracture criteria. Comparisons to the recently published fracture test data show that the traditional fracture criteria are not able to properly predict the fracture initiation conditions in zirconia/veneer bi-material joints. The modified maximum Tangential Stress criterion provides more accurate predictions of the experimental results than the traditional fracture criteria.
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Modified maximum Tangential Stress criterion for fracture behavior of zirconia/veneer interfaces.
Journal of the Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Mirmilad Mirsayar, Philip ParkAbstract:The veneering porcelain sintered on zirconia is widely used in dental prostheses, but repeated mechanical loadings may cause a fracture such as edge chipping or delamination. In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bi-layered components subjected to mixed mode loadings, the accuracy of a new and traditional fracture criteria are investigated. A modified maximum Tangential Stress criterion considering the effect of T-Stress and critical distance theory is introduced, and compared to three traditional fracture criteria. Comparisons to the recently published fracture test data show that the traditional fracture criteria are not able to properly predict the fracture initiation conditions in zirconia/veneer bi-material joints. The modified maximum Tangential Stress criterion provides more accurate predictions of the experimental results than the traditional fracture criteria.
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The role of T-Stress on kinking angle of interface cracks
Materials & Design, 2015Co-Authors: Mirmilad Mirsayar, Philip ParkAbstract:Abstract A modified version of the maximum Tangential Stress criterion is applied to predict the kinking angle of mixed mode interface cracks existing between two dissimilar isotropic elastic solids. The presence of a crack at the bi-material interface significantly affects on mechanical strength, and may eventually result in fracture. For interfaces with strong bonding, cracks may kink into one of the materials instead of growing through the interfaces. While the traditional maximum Tangential Stress criterion uses only the Stress intensity factors in mode I and mode II, the modified criterion takes into account the effect of T-Stress as well as the Stress intensity factors. Theoretical derivation of the criterion with T-Stress is introduced, and the kinking angles are calculated by both the traditional and modified criteria. The calculated kinking angles are compared to the experimental results for interface cracks reported in three previously published papers. The comparisons show that the modified criterion is capable of successfully predicting the kinking angles with a higher accuracy than previously suggested criteria as well as the traditional maximum Tangential Stress criterion.
Shubhra Misra - One of the best experts on this subject based on the ideXlab platform.
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measurements of the viscous Tangential Stress in the airflow above wind waves
Geophysical Research Letters, 2007Co-Authors: Fabrice Veron, G Saxena, Shubhra MisraAbstract:[1] The Stress and drag at the surface of the ocean are crucial parameters for both short term forecasting and the modeling of long-term global climate trends. However, the partition between viscous, turbulent, and wave Stresses, and in particular the effects of airflow separation are not well understood. We present direct measurements of the velocity in the airflow above wind-generated waves. We observe intermittent separation of the viscous sublayer past the crest of the wind waves leading to dramatic along-wave variability in the surface viscous Tangential Stress. These results hold for wind speeds that would normally be considered low to moderate. These viscous Stress measurements in the airflow above the wavy surface, and within the separated region are, to the best of the authors' knowledge, the first of this kind.
