The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Canh V Le - One of the best experts on this subject based on the ideXlab platform.
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Plastic Collapse analysis of mindlin reissner plates using a composite mixed finite element
International Journal for Numerical Methods in Engineering, 2016Co-Authors: L Leonetti, Canh V LeAbstract:Summary The paper proposes a mixed finite element model and experiments its capability in the analysis of Plastic Collapse Mindlin–Reissner plates. The model is based on simple assumptions for the unknown fields, ensuring that it is easy to formulate and implement. A composite triangular mesh is assumed over the domain. Within each triangular element, the displacement field is described by a quadratic interpolation, while the stress field is represented by a piece-wise constant description by introducing a subdivision of the element into three triangular regions. The Plastic Collapse analysis is formulated as quadratic and conic mathematical programming problem and is accomplished by an interior-point algorithm, which furnishes both the Collapse multiplier and the Collapse mechanism. A series of numerical experiments shows that the proposed model performs well in Plastic analysis, where it takes advantage of the absence of locking phenomena and the possibility of simply described discontinuities in the Plastic deformation field within the element. Copyright © 2015 John Wiley & Sons, Ltd.
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Plastic Collapse analysis of Mindlin–Reissner plates using a composite mixed finite element
International Journal for Numerical Methods in Engineering, 2015Co-Authors: L Leonetti, Canh V LeAbstract:Summary The paper proposes a mixed finite element model and experiments its capability in the analysis of Plastic Collapse Mindlin–Reissner plates. The model is based on simple assumptions for the unknown fields, ensuring that it is easy to formulate and implement. A composite triangular mesh is assumed over the domain. Within each triangular element, the displacement field is described by a quadratic interpolation, while the stress field is represented by a piece-wise constant description by introducing a subdivision of the element into three triangular regions. The Plastic Collapse analysis is formulated as quadratic and conic mathematical programming problem and is accomplished by an interior-point algorithm, which furnishes both the Collapse multiplier and the Collapse mechanism. A series of numerical experiments shows that the proposed model performs well in Plastic analysis, where it takes advantage of the absence of locking phenomena and the possibility of simply described discontinuities in the Plastic deformation field within the element. Copyright © 2015 John Wiley & Sons, Ltd.
Mulalo Doyoyo - One of the best experts on this subject based on the ideXlab platform.
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nucleation and propagation of Plastic Collapse bands in aluminum honeycomb
Journal of Applied Physics, 2003Co-Authors: Dirk Mohr, Mulalo DoyoyoAbstract:Uniaxial compression experiments on aluminum honeycomb are performed to investigate localization of deformation in cellular materials. Physical experiments, combined with numerical simulation of the honeycomb microstructure, feature the indepth analysis of the nucleation and propagation of Plastic Collapse bands. The onset of inelasticity is determined by the von Karman Collapse load for the honeycomb microstructure. The Plastic Collapse mechanism yields localization of deformation in the form of Collapse bands. At the same time, microstructural imperfections are generated in the vicinity of those bands. As a result, three microstructural configurations characterize the honeycomb specimen: Uncrushed material with deformation-induced imperfections, crushed material containing folded cell walls, and an active interface between the uncrushed and crushed regions. Globally, the active interface emerges as a flat propagating crushing front that travels down the specimen. It appears that the behavior of the inte...
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Nucleation and propagation of Plastic Collapse bands in aluminum honeycomb
Journal of Applied Physics, 2003Co-Authors: Dirk Mohr, Mulalo DoyoyoAbstract:The mechanics of the nucleation and propagation of Plastic Collapse bands in an aluminum honeycomb was studied. The macroscopic stress was governed by the Plastic dissipation during the uncrushed-to-crushed configuration change at the active interface. The results provide a framework for constitutive laws of materials that evolve statistically inhomogeneous microstructures under load.
L Leonetti - One of the best experts on this subject based on the ideXlab platform.
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Plastic Collapse analysis of mindlin reissner plates using a composite mixed finite element
International Journal for Numerical Methods in Engineering, 2016Co-Authors: L Leonetti, Canh V LeAbstract:Summary The paper proposes a mixed finite element model and experiments its capability in the analysis of Plastic Collapse Mindlin–Reissner plates. The model is based on simple assumptions for the unknown fields, ensuring that it is easy to formulate and implement. A composite triangular mesh is assumed over the domain. Within each triangular element, the displacement field is described by a quadratic interpolation, while the stress field is represented by a piece-wise constant description by introducing a subdivision of the element into three triangular regions. The Plastic Collapse analysis is formulated as quadratic and conic mathematical programming problem and is accomplished by an interior-point algorithm, which furnishes both the Collapse multiplier and the Collapse mechanism. A series of numerical experiments shows that the proposed model performs well in Plastic analysis, where it takes advantage of the absence of locking phenomena and the possibility of simply described discontinuities in the Plastic deformation field within the element. Copyright © 2015 John Wiley & Sons, Ltd.
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Plastic Collapse analysis of Mindlin–Reissner plates using a composite mixed finite element
International Journal for Numerical Methods in Engineering, 2015Co-Authors: L Leonetti, Canh V LeAbstract:Summary The paper proposes a mixed finite element model and experiments its capability in the analysis of Plastic Collapse Mindlin–Reissner plates. The model is based on simple assumptions for the unknown fields, ensuring that it is easy to formulate and implement. A composite triangular mesh is assumed over the domain. Within each triangular element, the displacement field is described by a quadratic interpolation, while the stress field is represented by a piece-wise constant description by introducing a subdivision of the element into three triangular regions. The Plastic Collapse analysis is formulated as quadratic and conic mathematical programming problem and is accomplished by an interior-point algorithm, which furnishes both the Collapse multiplier and the Collapse mechanism. A series of numerical experiments shows that the proposed model performs well in Plastic analysis, where it takes advantage of the absence of locking phenomena and the possibility of simply described discontinuities in the Plastic deformation field within the element. Copyright © 2015 John Wiley & Sons, Ltd.
Kunio Hasegawa - One of the best experts on this subject based on the ideXlab platform.
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Plastic Collapse Moment for Weld Overlay Pipe With Multiple Circumferential Flaws
ASME 2011 Pressure Vessels and Piping Conference: Volume 1, 2020Co-Authors: Kunio Hasegawa, Yinsheng Li, Masayoshi ShimomotoAbstract:Weld overlay is one of the useful repair methods for cracked piping that has been successfully applied for piping in many nuclear power plants. This paper proposes an approach for predicting Plastic Collapse moment for weld overlaid piping with single and multiple circumferential part-through flaws, using a new flaw depth parameter for weld overlay. The formulas for Plastic Collapse moments for weld overlaid pipes can be simply expressed by similar equations for a single flaw and multiple flaws using the parameter.Copyright © 2011 by ASME
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Plastic Collapse Stresses for Thick Wall Pipes With External Cracks
Volume 1: Codes and Standards, 2019Co-Authors: Kunio Hasegawa, Yinsheng Li, Valéry Lacroix, Vratislav MarešAbstract:Abstract Bending stress at Plastic Collapse for a circumferentially cracked pipe is predicted by limit load equation provided by the Appendix C of the ASME Code Section XI. The equation of the Appendix C is applicable for pipes with both external and internal surface cracks. On the other hand, the authors have developed an equation taking into account the pipe mean radii at non-cracked area and at cracked ligament area. From the comparison of Appendix C equation and the new equation, the Plastic Collapse stress estimated by the Appendix C equation gives 20 to 30% less conservative bending capacity prediction for external cracked pipes with small Rm/t, where Rm is the pipe mean radius and t is the pipe wall thickness. This paper discusses the limitation of the use of Rm/t for the Appendix C equation.
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Plastic Collapse Stresses Based on Flaw Combination Rules for Pipes Containing Two Circumferential Similar Flaws
Journal of Pressure Vessel Technology-transactions of The Asme, 2019Co-Authors: Kunio Hasegawa, Yinsheng Li, Valéry Lacroix, Bohumír StrnadelAbstract:When discrete multiple flaws are in the same plane, and they are close to each other, it can be determined whether they are combined or standalone in accordance with combination rules provided by fitness-for-service (FFS) codes. However, specific criteria of the rules are different among these FFS codes. On the other hand, Plastic Collapse bending stresses for stainless steel pipes with two circumferential similar flaws were obtained by experiments, and the prediction procedure for Collapse stresses for pipes with two similar flaws was developed analytically. Using the experimental data and the analytical procedure, Plastic Collapse stresses for pipes with two similar flaws are compared with the stresses in compliance with the flaw combination criteria. It is shown that the calculated Plastic Collapse stresses based on the flaw combination criteria are significantly different from the experimental and analytical stresses.
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Plastic Collapse Stresses for Pipes With Inner and Outer Circumferential Cracks
Journal of Pressure Vessel Technology-transactions of The Asme, 2019Co-Authors: Vratislav Mareš, Kunio Hasegawa, Yinsheng Li, Valéry LacroixAbstract:Bending stresses at incipient Plastic Collapse for pipes with circumferential surface cracks are predicted by net-section stress approach. Appendix C-5320 of ASME B&PV Code Section XI provides an equation of bending stress at the Plastic Collapse, where the equation is applicable for both inner and outer surface cracks. That is, the Collapse stresses for pipes with inner and outer surface cracks are the same, because of the pipe mean radius at the cracked section being entirely the same. Authors considered the separated pipe mean radii at the cracked ligament and at the uncracked ligament. Based on the balances of axial force and bending moment, equations of Plastic Collapse stresses for both inner and outer cracked pipes were developed. It is found that, when the crack angle and depth are the same, the Collapse stress for inner cracked pipe is slightly higher than that calculated by the Appendix C equation, and the Collapse stress for outer cracked pipe is slightly lower than that by the Appendix C equation, as can be expected. The Collapse stresses derived from the three equations are almost the same in most instances. However, for less common case where the crack angle and depth are very large for thick wall pipes, the differences among the three Collapse stresses become large. Code users pay attention to the margins of Plastic Collapse stresses for outer cracked pipes, when using Appendix C equation.
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Plastic Collapse Stresses for Pipes With Circumferential Twin Flaws Using Combination Rules
Volume 1A: Codes and Standards, 2018Co-Authors: Kunio Hasegawa, Yinsheng Li, Valéry Lacroix, Bohumír StrnadelAbstract:When discrete multiple flaws are in the same plane, and they are close to each other, it can be determined whether they are combined or standalone in accordance with combination rules provided by fitness-for-service (FFS) codes, such as ASME, JSME, BS7910, FKM, WES2805, etc. However, specific criteria of the rules are different amongst these FFS codes. On the other hand, Plastic Collapse bending stresses for stainless steel pipes with circumferential twin flaws were obtained by experiments and the prediction procedure for Collapse stresses for pipes with twin flaws were developed analytically. Using the experimental data and the analytical procedure, Plastic Collapse stresses for pipes with twin flaws are compared with the stresses in compliance with the combination criteria. It is shown that the calculated Plastic Collapse stresses based on the combination criteria are significantly different from the experimental and analytical stresses.
Masahiko Fujikubo - One of the best experts on this subject based on the ideXlab platform.
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Buckling/Plastic Collapse Behavior and Strength of Stiffened Plates
Buckling and Ultimate Strength of Ship and Ship-Like Floating Structures, 2020Co-Authors: Masahiko FujikuboAbstract:This chapter deals with buckling/Plastic Collapse behavior and the ultimate strength of stiffened plates subjected to various loads. At the beginning, it is explained how the stiffener affects on buckling behavior and buckling strength. Buckling/Plastic Collapse behavior and the ultimate strength of stiffened plate under longitudinal thrust are explained on the basis of nonlinear finite element method (FEM) analysis. Modeling extent in the FEM analysis is also explained.
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Fundamental Theory and Methods of Analysis to Simulate Buckling/Plastic Collapse Behavior
Buckling and Ultimate Strength of Ship and Ship-Like Floating Structures, 2020Co-Authors: Masahiko FujikuboAbstract:This chapter deals with the fundamental theory and method for the analysis of buckling/Plastic Collapse behavior of rectangular plates and stiffened plates subjected to combined in-plane loads. First, based on the fundamentals in the bucking Collapse behavior of plates and stiffened plate under various loading conditions, the deflection modes that should be used for the analytical method of elastic buckling and postbuckling analyses are explained. Then, the fundamental theories for the elastic buckling analysis and elastic large deflection analysis are presented including how to consider the effect of initial imperfections such as initial deflection and welding residual stresses. For the buckling/Plastic Collapse analysis of plates and stiffened plates considering both geometrical and material nonlinearities, the numerical approach such as the finite element method needs to be used. The fundamental theory for the elastoPlastic large deflection analysis is explained taking a four-node isoparametric shell element as an example. These theory and methods are used for the analytical and numerical calculations in the continued chapters in this book.
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Buckling/Plastic Collapse Behavior of Structural Members and Systems in Ship and Ship-Like Floating Structures
Buckling and Ultimate Strength of Ship and Ship-Like Floating Structures, 2020Co-Authors: Masahiko FujikuboAbstract:This chapter deals with buckling/Plastic Collapse behavior and the ultimate strength of structural members and systems, some of which are not the main structural members.
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Analysis of Buckling/Plastic Collapse Behaviour of Stiffened Plate under Thrust Using Simple Dynamical Plate Model
Journal of the Society of Naval Architects of Japan, 1998Co-Authors: Masahiko Fujikubo, Daisuke YanagiharaAbstract:A simple and efficient method of buckling/Plastic Collapse analysis of stiffened plates subjected to uni -axial thrust is presented. Plate part between stiffeners is divided into several plate elements in the stiffener direction. Thebuckling/Plastic Collapse behaviour of plate element is simulated using a simple dynamical model combining the results of elastic large deflection analysis and rigid Plastic mechanism analysis. The influence of a torsional stiffness of stiffeners on the local buckling strength of plate part is taken into account. Stiffener part is modeled by beam-column elements which can simulate a flexural-torsional buckling behaviour of thin-walled beams. Coupling the plate and beamcolumn elements, the buckling/Plastic Collapse behaviour of stiffened plates accompanied by both local and overall buckling can be analysed. It is also possible to simulate a localisation of Plastic deformation in a certain part of panel deflection and a resulting unloading in the remaining part, which have a large influence on the capacity beyond the ultimate strength.Using the proposed method, a series of buckling/Plastic Collapse analysis of stiffened plates is performed, and the applicability of the proposed method is discussed through a comparison with the ordinary elastoPlastic large deflection FEM analysis.
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buckling Plastic Collapse strength of ship bottom plating
Journal of the Society of Naval Architects of Japan, 1997Co-Authors: Osamu Niho, Masahiko Fujikubo, Balu Vargese, Keisuke MizutaniAbstract:To clarify the buckling/Plastic Collapse behaviour and strength of ship bottom plating, a series of elastoPlastic large deflection FEM analyses is performed on stiffened plates subjected to combined biaxial thrust and lateral pressure. A part of continuous stiffened plate is considered for analysis taking into account of symmetry conditions. A series of elastic large deflection FEM analyses is also performed on continuous plating without stiffeners to examine the influence of lateral pressure on the buckling behaviour of plating.It has been found that : (1) When initial deflection is in a hungry horse mode, bifurcation buckling takes place. The buckling strength increases with the increase in applied lateral pressure.(2) The buckling strength is increased also by the stiffeners, which constrain the rotation of panel along its edge. An analytical formula is derived to evaluate the local buckling strength of stiffened plate considering the influence of stiffeners.(3) With the increase in applied lateral pressure, the boundary condition of the panel between stiffeners changes from simply supported condition to clamped condition. This change increases the buckling/Plastic Collapse strength of stiffened plate.(4) With larger lateral pressure, yielding starts earlier. This reduces the buckling/Plastic Collapse strength of stiffened plate.(5) Owing to the opposite effects described above, the buckling/Plastic Collapse strength of stiffened plate takes its maximum value at a certain magnitude of lateral pressure, especially when transverse compression is dominant.(6) The formulae by classification societies give conservative buckling strength under bi-axial compression, and the bottom plating has much reserve up to the ultimate strength even when lateral pressure is acting.
