The Experts below are selected from a list of 205533 Experts worldwide ranked by ideXlab platform
Jeom Kee Paik - One of the best experts on this subject based on the ideXlab platform.
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residual ultimate strength of steel plates with longitudinal cracks under axial compression nonlinear finite element method investigations
Ocean Engineering, 2009Co-Authors: Jeom Kee PaikAbstract:Abstract The main objective of the present paper is to numerically examine the residual ultimate strength characteristics of steel plates with longitudinal cracks under axial compressive actions. The present paper is a sequel to the author's previous paper [Paik, J.K., 2008. Residual ultimate strength of steel plates with longitudinal cracks under axial compression—Experiments. Ocean Engineering 35, 1775–1783]. In contrast to the previous paper, the present paper deals with nonlinear finite element method investigations. Because the test programme is usually limited to a few test models in number for many reasons, the application of nonlinear finite element methods is often more beneficial to handle a more variety of parameters of influence. In the present paper, the insights developed from a series of ANSYS nonlinear finite element method computations are documented, where the effects of the crack orientation, the crack location, the crack size, the plate thickness, and the plate aspect ratio on the residual ultimate strength of steel plates with longitudinal cracks under axial compression are discussed. The insights developed from the present work will be useful for cracking Damage-Tolerant Design of steel-plated structures and also for health monitoring or condition assessment of aging steel-plated structures with cracking damages.
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residual ultimate strength of steel plates with longitudinal cracks under axial compression experiments
Ocean Engineering, 2008Co-Authors: Jeom Kee PaikAbstract:Abstract The main objective of the present study is to examine the residual ultimate strength characteristics of steel plates with cracking damages under axial compressive actions through experimental investigations. The present study is a sequel of the author's previous paper (Paik, J.K., Satish Kumar, Y.V., Lee, J.M., 2005. Ultimate strength of cracked plate elements under axial compression or tension. Thin-Walled Structures, 43, 237–272). In contrast to the previous paper which dealt with transverse cracks located in the direction normal to the axial loading direction, the present paper is concerned with longitudinal cracks which are located in parallel to the axial loading direction. Similar to the previous paper, the orientation/location and size of cracks inside the plates are varied for the present experimental investigations. The details of experimental results are documented. The database and insights developed from the present work will be useful for cracking Damage-Tolerant Design of steel-plated structures and also for condition assessment or health monitoring of aging steel-plated structures.
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ultimate strength of dented steel plates under edge shear loads
Thin-walled Structures, 2005Co-Authors: Jeom Kee PaikAbstract:Abstract The aims of this paper are to investigate the ultimate shear strength reduction characteristics of steel plates due to local impacts, and also to develop the ultimate shear strength Design formulae of dented steel plates. The ANSYS nonlinear finite element code is used to investigate the effects of shape, size (depth, diameter), and location of the denting on the ultimate strength behavior of simply supported steel plates under edge shear loads. A closed-form expression for predicting the ultimate shear strength of dented steel plates is derived by the regression analysis based on the computed results. The results and insights developed from the present study will be very useful for damage tolerant Design of steel plated structures with local denting.
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ultimate shear strength of plate elements with pit corrosion wastage
Thin-walled Structures, 2004Co-Authors: Jeom Kee Paik, Jaemyung LeeAbstract:Abstract The aim of the present paper is to investigate the ultimate strength characteristics of steel plate elements with pit corrosion wastage and under in-plane shear loads. A series of the ANSYS nonlinear finite element analyses for plate elements under in-plane shear loads are carried out, varying the degree of pit corrosion intensity and the plate geometric properties. Closed-form Design formulae for the ultimate strength of pitted plates under edge shear, which are essentially needed for the ultimate limit state based risk or reliability assessment of corroded structures, are derived by the regression analysis of the computed results. The insights developed from the present study will be very useful for damage tolerant Design of plated structures with pit corrosion wastage.
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ultimate strength of dented steel plates under axial compressive loads
International Journal of Mechanical Sciences, 2003Co-Authors: Jeom Kee PaikAbstract:In this paper the ultimate strength characteristics of dented steel plates under axial compressive loads are investigated using the ANSYS nonlinear finite element code. The effects of shape, size (depth, diameter), and location of the dent on the ultimate strength behavior of simply supported steel plates under axial thrust are studied. A closed-form formula for predicting the ultimate compressive strength of dented steel plates are empirically derived by curve fitting based on the computed results. The results and insights developed in the present study will be useful for damage tolerant Design of steel plated structures with local denting.
Jesper Ankersen - One of the best experts on this subject based on the ideXlab platform.
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delamination growth directionality and the subsequent migration processes the key to damage tolerant Design
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Carla Canturri, Emile S Greenhalgh, S T Pinho, Jesper AnkersenAbstract:Abstract Delamination has been recognised as one of the most challenging hurdles in using laminated composites, and has been the focus of considerable research over the last three decades. The research reported in this paper investigated the influence of ply interface on the delamination propagation processes. Experimental evidence is presented which illustrates that delamination does not grow in a self-similar manner. Instead, delaminations were shown to propagate preferentially in the direction of one ply at the delaminating interface; which ply was dictated by the orientation of the principal delaminating stress at the ply interface. In conjunction with the experimental studies, an initial methodology for modelling delamination directionality is presented. The results of this study have considerable implications for tailoring stacking sequences to promote delamination migration and thus enhance damage tolerance.
Mauro Madia - One of the best experts on this subject based on the ideXlab platform.
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damage tolerant Design of additively manufactured metallic components subjected to cyclic loading state of the art and challenges
Progress in Materials Science, 2021Co-Authors: Uwe Zerbst, Xiang Zhang, Giovanni Bruno, Jeanyves Buffiere, Thomas Wegener, Thomas Niendorf, Nikolai Kashaev, Giovanni Meneghetti, Nik Hrabe, Mauro MadiaAbstract:Undoubtedly, a better understanding and the further development of approaches for damage tolerant component Design of AM parts are among the most significant challenges currently facing the use of these new technologies. This article presents a thorough overview of the workshop discussions. It aims to provide a review of the parameters affecting the damage tolerance of parts produced by additive manufacturing (shortly, AM parts) with special emphasis on the process parameters intrinsic to the AM technologies, the resulting defects and the residual stresses. Based on these aspects, basic concepts are reviewed and critically discussed specifically for AM materials: Criteria for damage tolerant component Design;Criteria for the determination of fatigue and fracture properties;Strategies for the determination of the fatigue life in dependence of different manufacturing conditions;Methods for the quantitative characterization of microstructure and defects;Methods for the determination of residual stresses;Effect of the defects and the residual stresses on the fatigue life and behaviour. We see that many of the classic concepts need to be expanded in order to fit with the particular microstructure (grain size and shape, crystal texture) and defect distribution (spatial arrangement, size, shape, amount) present in AM (in particular laser powder bed fusion). For instance, 3D characterization of defects becomes essential, since the defect shapes in AM are diverse and impact the fatigue life in a different way than in the case of conventionally produced components. Such new concepts have immediate consequence on the way one should tackle the determination of the fatigue life of AM parts; for instance, since a classification of defects and a quantification of the tolerable shapes and sizes is still missing, a new strategy must be defined, whereby theoretical calculations (e.g. FEM) allow determining the maximum tolerable defect size, and non-destructive testing (NDT) techniques are required to detect whether such defects are indeed present in the component. Such examples show how component Design, damage and failure criteria, and characterization (and/or NDT) become for AM parts fully interlinked. We conclude that the homogenization of these fields represents the current challenge for the engineer and the materials scientist.
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About the fatigue crack propagation threshold of metals as a Design criterion - A review
Engineering Fracture Mechanics, 2016Co-Authors: Uwe Zerbst, Christine Sarrazin-baudoux, Hans Peter Gänser, Michael Vormwald, Reinhard Pippan, Mauro MadiaAbstract:The fatigue crack propagation threshold δKth is of paramount importance for any kind of damage tolerant Design, but in contrast to this importance, the determination and application of the parameter is not on the firm ground as previously assumed. The paper discusses questions of its experimental determination as well as of its application to components. In both fields, new questions have been raised with the potential to challenge or modify long-standing knowledge. Against this background, the paper is an attempt to systematize the established knowledge as well as questions and open issues.
R O Ritchie - One of the best experts on this subject based on the ideXlab platform.
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foreign object damage and high cycle fatigue of ti 6al 4v
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2001Co-Authors: J. O. Peters, R O RitchieAbstract:Abstract Recent high-cycle fatigue (HCF) related failures of gas-turbine jet engines have prompted a re-examination of the Design methodologies for HCF-critical components, such as titanium alloy turbine blades. As foreign-object damage (FOD) from ingested debris is a key concern for HCF-related failures of such blades, the current study is focused on the role of simulated high velocity FOD in affecting the initiation and early growth of small surface fatigue cracks in a Ti–6Al–4V alloy, processed for typical blade applications. It is found that resistance to HCF is markedly reduced, primarily due to earlier fatigue crack initiation. The mechanistic effect of FOD on such premature fatigue crack initiation and the subsequent crack growth is discussed in terms of four prominent factors: (i) the presence of small microcracks in the damaged zone; (ii) the stress concentration associated with the FOD indentation; (iii) the localized presence of tensile residual hoop stresses at the base and rim of the indent sites; and (iv) microstructural damage from FOD-induced plastic deformation. In view of the in-service conditions, i.e., small crack sizes, high frequency (>1 kHz) vibratory loading and (depending on the blade span location) high mean stress levels, a Damage-Tolerant Design approach, based on the concept of a threshold for no fatigue-crack growth, appears to offer a preferred solution. It is shown that FOD-initiated cracks that are of a size comparable with microstructural dimensions can propagate at applied stress-intensity ranges on the order of ΔK∼1 MPa√m.
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fatigue of aluminium lithium alloys
International Materials Reviews, 1992Co-Authors: K Venkateswara T Rao, R O RitchieAbstract:Abstract Aluminium-lithium alloys are a class of low density, high strength, high stiffness monolithic metallic materials that have been identified as prime candidates for replacing 2000 and 7000 series aluminium alloys currently used in commercial and military aircraft. In this review, the cyclic fatigue strength and fatigue crack propagation characteristics of aluminium-lithium alloys are reviewed in detail with emphasis on the underlying micromechanisms associated with crack advance and their implications to damage tolerant Design and lifetime computations. Compared with traditional aerospace aluminium alloys, results on the fatigue of binary Al-Li, experimental Al-Li-Cu, and near commercial Al-Li-Cu-Zr and Al-Li-Cu-Mg-Zr systems indicate that alloying with Li degrades the lowcycle fatigue resistance, though high-cycle fatigue behaviour remains comparable. The alloys, however, display superior (long crack) fatigue crack growth properties, resulting from a prominent role of crack tip shielding, principa...
Peixue Wang - One of the best experts on this subject based on the ideXlab platform.
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statistical analysis of fatigue crack growth behavior for grade b cast steel
Materials & Design, 2011Co-Authors: Tatsuo Sakai, Peixue WangAbstract:Abstract Tests for fatigue crack growth rate (FCGR) and crack-tip opening displacement (CTOD) were performed to clarify the fatigue crack growth behavior of a railway grade B cast steel. The threshold values of this steel with specific survival probabilities are evaluated, in which the mean value is 8.3516 MPa m 1/2 , very similar to the experimental value, about 8.7279 MPa m 1/2 . Under the conditions of plane strain and small-scale yielding, the values of fracture toughness for this steel with specific survival probabilities are converted from the corresponding critical CTOD values, in which the mean value is about 138.4256 MPa m 1/2 . In consideration of the inherent variability of crack growth rates, six statistical models are proposed to represent the probabilistic FCGR curves of this steel in entire crack propagation region from the viewpoints of statistical evaluation on the number of cycles at a given crack size and the crack growth rate at a given stress intensity factor range, stochastic characteristic of crack growth as well as statistical analysis of coefficient and exponent in FCGR power law equation. Based on the model adequacy checking, result shows that all models are basically in good agreement with test data. Although the probabilistic Damage-Tolerant Design based on some models may involve a certain amount of risk in stable crack propagation region, they just accord with the fact that the dispersion degree of test data in this region is relatively smaller.
