The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Dungan Wang - One of the best experts on this subject based on the ideXlab platform.
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mode i Stress Intensity Factor solutions for spot welds in lap shear specimens
International Journal of Solids and Structures, 2007Co-Authors: Dungan WangAbstract:The analytical solutions of the mode I Stress Intensity Factor for spot welds in lap-shear specimens are investigated based on the classical Kirchhoff plate theory for linear elastic materials. First, closed-form solutions for an infinite plate containing a rigid inclusion under counter bending conditions are derived. The development of the closed-form solutions is then used as a guide to develop approximate closed-form solutions for a finite square plate containing a rigid inclusion under counter bending conditions. Based on the J integral, the closed-form solutions are used to develop the analytical solutions of the mode I Stress Intensity Factor for spot welds in lap-shear specimens of large and finite sizes. The analytical solutions of the mode I Stress Intensity Factor based on the solutions for infinite and finite square plates with an inclusion are compared with the results of the three-dimensional finite element computations of lap-shear specimens with various ratios of the specimen half width to the nugget radius. The results indicate that the mode I Stress Intensity Factor solution based on the finite square plate model with an inclusion agrees well with the computational results for lap-shear specimens for the ratio of the half specimen width to the nugget radius between 4 and 15. Finally, a set of the closed-form Stress Intensity Factor solutions for lap-shear specimens at the critical locations are proposed for future applications.
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a computational study of local Stress Intensity Factor solutions for kinked cracks near spot welds in lap shear specimens
International Journal of Solids and Structures, 2005Co-Authors: Dungan WangAbstract:In this paper, the local Stress Intensity Factor solutions for kinked cracks near spot welds in lap-shear specimens are investigated by finite element analyses. Based on the experimental observations of kinked crack growth mechanisms in lap-shear specimens under cyclic loading conditions, three-dimensional and two-dimensional plane-strain finite element models are established to investigate the local Stress Intensity Factor solutions for kinked cracks emanating from the main crack. Semi-elliptical cracks with various kink depths are assumed in the three-dimensional finite element analysis. The local Stress Intensity Factor solutions at the critical locations or at the maximum depths of the kinked cracks are obtained. The computational local Stress Intensity Factor solutions at the critical locations of the kinked cracks of finite depths are expressed in terms of those for vanishing kink depth based on the global Stress Intensity Factor solutions and the analytical kinked crack solutions for vanishing kink depth. The three-dimensional finite element computational results show that the critical local mode I Stress Intensity Factor solution increases and then decreases as the kink depth increases. When the kink depth approaches to 0, the critical local mode I Stress Intensity Factor solution appears to approach to that for vanishing kink depth based on the global Stress Intensity Factor solutions and the analytical kinked crack solutions for vanishing kink depth. The two-dimensional plane-strain computational results indicate that the critical local mode I Stress Intensity Factor solution increases monotonically and increases substantially more than that based on the three-dimensional computational results as the kink depth increases. The local Stress Intensity Factor solutions of the kinked cracks of finite depths are also presented in terms of those for vanishing kink depth based on the global Stress Intensity Factor solutions and the analytical kinked crack solutions for vanishing kink depth. Finally, the implications of the local Stress Intensity Factor solutions for kinked cracks on fatigue life prediction are discussed.
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geometric functions of Stress Intensity Factor solutions for spot welds in lap shear specimens
International Journal of Solids and Structures, 2005Co-Authors: Dungan WangAbstract:In this paper, the Stress Intensity Factor solutions for spot welds in U-shape specimens are investigated by finite element analyses. Three-dimensional finite element models are developed for U-shape specimens to obtain accurate Stress Intensity Factor solutions. In contrast to the existing investigations of the Stress Intensity Factor solutions based on the finite element analyses, various ratios of the sheet thickness, half specimen width, half specimen length, and corner radius to the nugget radius are considered in this investigation. The computational results confirm the functional dependence on the nugget radius and sheet thickness of Zhang’s analytical solutions. The computational results provide a geometric function in terms of the normalized half specimen width, normalized half specimen length, and normalized corner radius to Zhang’s analytical solutions. The computational results also provide a geometric function in terms of the aspect ratio of the specimen to complete Lin and Pan’s analytical solution. Finally, based on the analytical and computational results, the dimensions of U-shape specimens are suggested.
Qun Zhao - One of the best experts on this subject based on the ideXlab platform.
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a method for Stress Intensity Factor calculation of infinite plate containing multiple hole edge cracks
International Journal of Fatigue, 2012Co-Authors: Jinfang Zhao, Qun ZhaoAbstract:Abstract Multiple site damage is the occurrence of small fatigue cracks at several sites within aging aircraft structures. Focusing on this typical structure, an analytical method for calculating the Stress Intensity Factor of an infinite plate containing multiple hole-edge cracks was introduced in this paper. The properties of complex variable functions are used to evaluate the Stress function. The approximate superposition method is applied to solve Stress Intensity Factor problems on multiple holes. The equivalent crack is introduced to modify the method. Some numerical examples of an infinite plate containing two hole-edge cracks are examined by the method. By comparing the analytical and finite element analysis results it was realized that the analytical results are accurate and reliable. This modified analytical method is easier to apply than some traditional analytical methods and can provide Stress Intensity Factor solutions for an infinite plate containing a random distribution of multiple hole-edge cracks.
François Hild - One of the best experts on this subject based on the ideXlab platform.
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Stress Intensity Factor measurements from digital image correlation post processing and integrated approaches
International Journal of Fracture, 2006Co-Authors: Stéphane Roux, François HildAbstract:Digital image correlation is an appealing technique for studying crack propagation in brittle materials such as ceramics. A case study is discussed where the crack geometry, and the crack opening displacement are evaluated from image correlation by following two different measurement and identification routes. The displacement uncertainty can reach the nanometer range even though optical pictures are dealt with. The Stress Intensity Factor is estimated with a 7% uncertainty in a complex loading set-up without having to resort to a numerical modelling of the experiment.
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Stress Intensity Factor measurements from digital image correlation: Post-processing and integrated approaches
International Journal of Fracture, 2006Co-Authors: Stéphane Roux, François HildAbstract:Digital image correlation is an appealing technique for studying crack propagation in brittle materials such as ceramics. A case study is discussed where the crack geometry, and the crack opening displacement are evaluated from image correlation by following two different measurement and identification routes. The displacement uncertainty can reach the nanometer range even though optical pictures are dealt with. The Stress Intensity Factor is estimated with a 7% uncertainty in a complex loading set-up without having to resort to a numerical modelling of the experiment. © Springer 2006.
Dieter Radaj - One of the best experts on this subject based on the ideXlab platform.
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state of the art review on extended Stress Intensity Factor concepts
Fatigue & Fracture of Engineering Materials & Structures, 2014Co-Authors: Dieter RadajAbstract:The Stress Intensity Factor concept for describing the Stress field at pointed crack or slit tips is well known from fracture mechanics. It has been substantially extended since Williams' basic contribution (1952) on Stress fields at angular corners. One extension refers to pointed V-notches with Stress intensities depending on the notch opening angle. The loading-mode-related simple notch Stress Intensity Factors K1, K2 and K3 are introduced. Another extension refers to rounded notches with crack shape or V-notch shape in two variants: parabolic, elliptic or hyperbolic notches (‘blunt notches’) on the one hand and root hole notches (‘keyholes’ when considering crack shapes) on the other hand. Here, the loading-mode-related generalised notch Stress Intensity Factors K1ρ, K2ρ and K3ρ are defined. The concepts of elastic Stress Intensity Factor, notch Stress Intensity Factor and generalised notch Stress Intensity Factor are extended into the range of elastic–plastic (work-hardening) or perfectly plastic notch tip or notch root behaviour. Here, the plastic notch Stress Intensity Factors K1p, K2p and K3p are of relevance. The elastic notch Stress Intensity Factors are used to describe the fatigue strength of fillet-welded attachment joints. The fracture toughness of brittle materials may also be evaluated on this basis. The plastic notch Stress Intensity Factors characterise the Stress and strain field at pointed V-notch tips. A new version of the Neuber rule accounting for the influence of the notch opening angle is presented.
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State‐of‐the‐art review on extended Stress Intensity Factor concepts
Fatigue & Fracture of Engineering Materials & Structures, 2013Co-Authors: Dieter RadajAbstract:The Stress Intensity Factor concept for describing the Stress field at pointed crack or slit tips is well known from fracture mechanics. It has been substantially extended since Williams' basic contribution (1952) on Stress fields at angular corners. One extension refers to pointed V-notches with Stress intensities depending on the notch opening angle. The loading-mode-related simple notch Stress Intensity Factors K1, K2 and K3 are introduced. Another extension refers to rounded notches with crack shape or V-notch shape in two variants: parabolic, elliptic or hyperbolic notches (‘blunt notches’) on the one hand and root hole notches (‘keyholes’ when considering crack shapes) on the other hand. Here, the loading-mode-related generalised notch Stress Intensity Factors K1ρ, K2ρ and K3ρ are defined. The concepts of elastic Stress Intensity Factor, notch Stress Intensity Factor and generalised notch Stress Intensity Factor are extended into the range of elastic–plastic (work-hardening) or perfectly plastic notch tip or notch root behaviour. Here, the plastic notch Stress Intensity Factors K1p, K2p and K3p are of relevance. The elastic notch Stress Intensity Factors are used to describe the fatigue strength of fillet-welded attachment joints. The fracture toughness of brittle materials may also be evaluated on this basis. The plastic notch Stress Intensity Factors characterise the Stress and strain field at pointed V-notch tips. A new version of the Neuber rule accounting for the influence of the notch opening angle is presented.
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Extended Stress Intensity Factor Concepts
Advanced Methods of Fatigue Assessment, 2013Co-Authors: Dieter RadajAbstract:The Stress Intensity Factor concept for describing the Stress field at pointed crack or slit tips is well known from fracture mechanics. It is substantially extended here in two directions. One extension refers to pointed V-notches with Stress intensities depending on the notch opening angle. The loading mode related notch Stress Intensity Factors K 1, K 2 and K 3 are introduced. Another extension refers to rounded notches with crack shape or V-notch shape in two variants: parabolic, elliptic or hyperbolic notches (‘blunt notches’) on the one hand and root hole notches (‘keyholes’ when considering crack shapes) on the other hand. Here, the loading mode related generalised notch Stress Intensity Factors K 1ρ , K 2ρ and K 3ρ are defined. The concepts of elastic Stress Intensity Factor, notch Stress Intensity Factor and generalised notch Stress Intensity Factor are extended into the range of elastic-plastic (work-hardening) or perfectly plastic notch tip or notch root behaviour. Here, the plastic notch Stress Intensity Factors K 1p, K 2p and K 3p are of relevance. The original Stress Intensity Factor concept is also transferred from cracks or slits to rigid thin inclusions.
Jungchae Jeong - One of the best experts on this subject based on the ideXlab platform.
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determining the Stress Intensity Factor of a material with an artificial neural network from acoustic emission measurements
Ndt & E International, 2004Co-Authors: Dongjin Yoon, Jungchae JeongAbstract:An artificial neural (ANN) network was trained to recognize the Stress Intensity Factor in the interval from microcrack to fracture from acoustic emission (AE) measurements on compact tension specimens. The specimens were made from structural steel SWS490B whilst the ANN had a 5-14-1 structure. The number of neurons in the input layers was five inputs of the AE parameters such as ring-down counts, rise time, energy, event duration and peak amplitude. The performance of the ANN was tested using a specific set of the AE data. The ANN is a promising tool for predicting the Stress Intensity Factor of material using AE data.
