The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Fengbao Lin - One of the best experts on this subject based on the ideXlab platform.
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treatment of Corner Node problems and its singularity
Engineering Analysis With Boundary Elements, 1994Co-Authors: Geng Yan, Fengbao LinAbstract:Abstract In boundary element analyses, special treatments have to be applied at geometric Corner Nodes in order to achieve a higher accuracy of the boundary element results. This paper first reviews the existing methods in the treatment of Corner Node problems, and then proposes the boundary point element method, which possesses continuous boundary displacements and discontinuous tractions at the geometric Corners. A way to deal with the singularity that occurs when displacements are prescribed at both Nodes of a boundary point element is also presented. Numerical analyses of various typical examples are carried out using different treatments for the Corner Node problems and their performances are compared. It is shown that the boundary point element method is an accurate and effective approach in treating the problems.
Massimo Cuomo - One of the best experts on this subject based on the ideXlab platform.
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Crack opening conditions at 'Corner Nodes' in FE analysis with cracking along mesh lines
Engineering Fracture Mechanics, 2007Co-Authors: Daniela Ciancio, Ignacio Carol, Massimo CuomoAbstract:On the basis of a recent work proposed by the authors on a double-minimization method for evaluating inter-element forces and stresses transmitted across mesh lines, the crack opening conditions at a Corner Node of the FE mesh, from where several lines (potential cracks) emanate, is examined in this paper. The study is developed locally as a post-processing step of a standard displacement-based FE calculation, in terms of an always-increasing external (macroscopic) load factor μ. The cracking laws for each potential crack line are assumed rigid-plastic with hyperbolic failure criterion in terms of normal and shear components of the stress traction at that point. It is observed that, as μ increases, in general such point may undergo up to four phases of evolution until a crack can effectively open through it. First, while stress tractions across mesh lines at the point are all below cracking criterion, forces may be evaluated with the double minimization method recently proposed. Second, cracking criterion is reached for one of the lines only. Stress evaluation requires a modified minimization method with one (hyperbolic) constraint; however, crack still does not open at the Node because of the lack of kinematic continuity. Third, cracking criterion is satisfied for a second of the lines converging at the nodal point. Stress tractions may then be calculated with a system of equations involving the two hyperbolic constraints alone and no minimization is needed. But in general the through crack cannot open yet at this stage because of non-coincident flow rules, until either (i) a third line reaches the cracking criterion, or (ii) these get reoriented to exhibit parallel directions in the global reference system. Two simple examples of application are provided which illustrates the development of the various cracking stages and shows different situations that may take place.
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On inter-element forces in the FEM-displacement formulation, and implications for stress recovery
International Journal for Numerical Methods in Engineering, 2006Co-Authors: Daniela Ciancio, Ignacio Carol, Massimo CuomoAbstract:This paper describes a new technique for the determination of the inter-element forces and tractions, as well as stress state at Nodes, as a post-processing step after the solution of standard FE-displacement calculation. The work is motivated in the context of a broader development of a procedure to simulate fracture processes using a discrete approach without the need of double-Noded interface elements. The technique, easily implementable, is based on the double minimization of an objective function, representing the error between the inter-element stress tractions and the projection of the best-fit stress tensor T along the planes of the interfaces converging at an element Corner Node. The formulation is illustrated with some basic examples in which the resulting stress tensors and inter-element forces are compared to theoretical solutions and to the results obtained by using a traditional stress average smoothing method.
Jeong-ho Kim - One of the best experts on this subject based on the ideXlab platform.
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Development of a New Cracked Mindlin Plate Element
ISRN Civil Engineering, 2011Co-Authors: Chengyin Liu, John T. Dewolf, Jeong-ho KimAbstract:This work addresses the development of a new four-Noded rectangular Mindlin plate bending element (MP4C) with a crack which consists of three degrees of freedom (DOF) at each Corner Node. The crack in the element is assumed to be not closed and nonpropagating. The crack affects the elastic strain energy and the flexibility matrix of the element, whereas the mass matrix remains unchanged. The complete element stiffness matrix is constructed as the inverse of the combined flexibility matrix of both noncracked and cracked elements. To evaluate the behavior of the proposed cracked Mindlin plate element, numerical examples are provided. They are based on developing user subroutines in ABAQUS. The finite element analysis results using the developed plate element are in excellent agreement with those reported in previous work. The cracked plate element developed in this paper provides a simple and robust approach to model the real service conditions in plate-like structures.
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Rectangular Mindlin plate element with a through crack
Sensors and Smart Structures Technologies for Civil Mechanical and Aerospace Systems 2007, 2007Co-Authors: Chengyin Liu, John T. Dewolf, Jeong-ho KimAbstract:This work addresses the development of a new four-Noded rectangular Mindlin plate bending element (MP4C) with a crack which consists of three degrees of freedom at each Corner Node. The crack in the element is assumed to be not closed and non-propagating. The crack affects the elastic strain energy and the flexibility matrix of the element, whereas the mass matrix remains unchanged. The complete element stiffness matrix is constructed as the inverse of the combined flexibility matrix of both non-cracked and cracked elements. To evaluate the behavior of the proposed cracked Mindlin plate element, numerical examples are provided. They are based on developing user subroutines in the commercial finite element software ABAQUS. The finite element analysis results using the developed plate element are in excellent agreement with those reported in previous work. The cracked plate element developed in this paper provides a simple and robust approach to model the real service conditions in plate-like structures.
Geng Yan - One of the best experts on this subject based on the ideXlab platform.
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treatment of Corner Node problems and its singularity
Engineering Analysis With Boundary Elements, 1994Co-Authors: Geng Yan, Fengbao LinAbstract:Abstract In boundary element analyses, special treatments have to be applied at geometric Corner Nodes in order to achieve a higher accuracy of the boundary element results. This paper first reviews the existing methods in the treatment of Corner Node problems, and then proposes the boundary point element method, which possesses continuous boundary displacements and discontinuous tractions at the geometric Corners. A way to deal with the singularity that occurs when displacements are prescribed at both Nodes of a boundary point element is also presented. Numerical analyses of various typical examples are carried out using different treatments for the Corner Node problems and their performances are compared. It is shown that the boundary point element method is an accurate and effective approach in treating the problems.
Daniela Ciancio - One of the best experts on this subject based on the ideXlab platform.
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Crack opening conditions at 'Corner Nodes' in FE analysis with cracking along mesh lines
Engineering Fracture Mechanics, 2007Co-Authors: Daniela Ciancio, Ignacio Carol, Massimo CuomoAbstract:On the basis of a recent work proposed by the authors on a double-minimization method for evaluating inter-element forces and stresses transmitted across mesh lines, the crack opening conditions at a Corner Node of the FE mesh, from where several lines (potential cracks) emanate, is examined in this paper. The study is developed locally as a post-processing step of a standard displacement-based FE calculation, in terms of an always-increasing external (macroscopic) load factor μ. The cracking laws for each potential crack line are assumed rigid-plastic with hyperbolic failure criterion in terms of normal and shear components of the stress traction at that point. It is observed that, as μ increases, in general such point may undergo up to four phases of evolution until a crack can effectively open through it. First, while stress tractions across mesh lines at the point are all below cracking criterion, forces may be evaluated with the double minimization method recently proposed. Second, cracking criterion is reached for one of the lines only. Stress evaluation requires a modified minimization method with one (hyperbolic) constraint; however, crack still does not open at the Node because of the lack of kinematic continuity. Third, cracking criterion is satisfied for a second of the lines converging at the nodal point. Stress tractions may then be calculated with a system of equations involving the two hyperbolic constraints alone and no minimization is needed. But in general the through crack cannot open yet at this stage because of non-coincident flow rules, until either (i) a third line reaches the cracking criterion, or (ii) these get reoriented to exhibit parallel directions in the global reference system. Two simple examples of application are provided which illustrates the development of the various cracking stages and shows different situations that may take place.
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On inter-element forces in the FEM-displacement formulation, and implications for stress recovery
International Journal for Numerical Methods in Engineering, 2006Co-Authors: Daniela Ciancio, Ignacio Carol, Massimo CuomoAbstract:This paper describes a new technique for the determination of the inter-element forces and tractions, as well as stress state at Nodes, as a post-processing step after the solution of standard FE-displacement calculation. The work is motivated in the context of a broader development of a procedure to simulate fracture processes using a discrete approach without the need of double-Noded interface elements. The technique, easily implementable, is based on the double minimization of an objective function, representing the error between the inter-element stress tractions and the projection of the best-fit stress tensor T along the planes of the interfaces converging at an element Corner Node. The formulation is illustrated with some basic examples in which the resulting stress tensors and inter-element forces are compared to theoretical solutions and to the results obtained by using a traditional stress average smoothing method.