The Experts below are selected from a list of 7701 Experts worldwide ranked by ideXlab platform
H L Schreyer - One of the best experts on this subject based on the ideXlab platform.
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fluid membrane interaction based on the material point method
International Journal for Numerical Methods in Engineering, 2000Co-Authors: Allen R York, Deborah Sulsky, H L SchreyerAbstract:The material point method (MPM) uses unconnected, Lagrangian, material points to discretize solids, fluids or membranes. All variables in the solution of the continuum equations are associated with these points; so, for example, they carry mass, velocity, stress and strain. A background Eulerian Mesh is used to solve the momentum equation. Data mapped from the material points are used to initialize variables on the background Mesh. In the case of multiple materials, the stress from each material contributes to forces at nearby Mesh points, so the solution of the momentum equation includes all materials. The Mesh solution then updates the material point values. This simple algorithm treats all materials in a uniform way, avoids complicated Mesh construction and automatically applies a noslip contact algorithm at no additional cost. Several examples are used to demonstrate the method, including simulation of a pressurized membrane and the impact of a probe with a pre-inflated airbag. Copyright © 2000 John Wiley & Sons, Ltd.
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axisymmetric form of the material point method with applications to upsetting and taylor impact problems
Computer Methods in Applied Mechanics and Engineering, 1996Co-Authors: Deborah Sulsky, H L SchreyerAbstract:Abstract The material point method is an evolution of particle-in-cell methods which utilize two Meshes, one a material or Lagrangian Mesh defined over material of the body under consideration, and the second a spatial or Eulerian Mesh defined over the computational domain. Although Meshes are used, they have none of the negative aspects normally associated with conventional Eulerian or Lagrangian approaches. The advantages of both the Eulerian and Lagrangian methods are achieved by using the appropriate frame for each aspect of the computation, with a mapping between the two Meshes that is performed at each step in the loading process. The numerical dissipation normally displayed by an Eulerian method because of advection is avoided by using a Lagrangian step; the Mesh distortion associated with the Lagrangian method is prevented by mapping to a user-controlled Mesh. Furthermore, explicit material points can be tracked through the process of deformation, thereby alleviating the need to map history variables. As a consequence, problems which have caused severe numerical difficulties with conventional methods are handled fairly routinely. Examples of such problems are the upsetting of billets and the Taylor problem of cylinders impacting a rigid wall. Numerical solutions to these problems are obtained with the material point method and where possible comparisons with experimental data and existing numerical solutions are presented.
François Jouve - One of the best experts on this subject based on the ideXlab platform.
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a level set method for vibration and multiple loads structural optimization
Computer Methods in Applied Mechanics and Engineering, 2005Co-Authors: Gregoire Allaire, François JouveAbstract:Abstract We extend the level-set method for shape and topology optimization to new objective functions such as eigenfrequencies and multiple loads. This method is based on a combination of the classical shape derivative and of the Osher–Sethian level-set algorithm for front propagation. In two and three space dimensions we maximize the first eigenfrequency or we minimize a weighted sum of compliances associated to different loading configurations. The shape derivative is used as an advection velocity in a Hamilton–Jacobi equation for changing the shape. This level-set method is a low-cost shape capturing algorithm working on a fixed Eulerian Mesh and it can easily handle topology changes.
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structural optimization using sensitivity analysis and a level set method
Journal of Computational Physics, 2004Co-Authors: Gregoire Allaire, François Jouve, Ancamaria ToaderAbstract:In the context of structural optimization we propose a new numerical method based on a combination of the classical shape derivative and of the level-set method for front propagation. We implement this method in two and three space dimensions for a model of linear or nonlinear elasticity. We consider various objective functions with weight and perimeter constraints. The shape derivative is computed by an adjoint method. The cost of our numerical algorithm is moderate since the shape is captured on a fixed Eulerian Mesh. Although this method is not specifically designed for topology optimization, it can easily handle topology changes. However, the resulting optimal shape is strongly dependent on the initial guess.
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a level set method for shape optimization
Comptes Rendus Mathematique, 2002Co-Authors: Gregoire Allaire, François Jouve, Ancamaria ToaderAbstract:We study a level-set method for numerical shape optimization of elastic structures. Our approach combines the level-set algorithm of Osher and Sethian with the classical shape gradient. Although this method is not specifically designed for topology optimization, it can easily handle topology changes for a very large class of objective functions. Its cost is moderate since the shape is captured on a fixed Eulerian Mesh. To cite this article: G. Allaire et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 1125–1130.
Gregoire Allaire - One of the best experts on this subject based on the ideXlab platform.
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a level set method for vibration and multiple loads structural optimization
Computer Methods in Applied Mechanics and Engineering, 2005Co-Authors: Gregoire Allaire, François JouveAbstract:Abstract We extend the level-set method for shape and topology optimization to new objective functions such as eigenfrequencies and multiple loads. This method is based on a combination of the classical shape derivative and of the Osher–Sethian level-set algorithm for front propagation. In two and three space dimensions we maximize the first eigenfrequency or we minimize a weighted sum of compliances associated to different loading configurations. The shape derivative is used as an advection velocity in a Hamilton–Jacobi equation for changing the shape. This level-set method is a low-cost shape capturing algorithm working on a fixed Eulerian Mesh and it can easily handle topology changes.
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structural optimization using sensitivity analysis and a level set method
Journal of Computational Physics, 2004Co-Authors: Gregoire Allaire, François Jouve, Ancamaria ToaderAbstract:In the context of structural optimization we propose a new numerical method based on a combination of the classical shape derivative and of the level-set method for front propagation. We implement this method in two and three space dimensions for a model of linear or nonlinear elasticity. We consider various objective functions with weight and perimeter constraints. The shape derivative is computed by an adjoint method. The cost of our numerical algorithm is moderate since the shape is captured on a fixed Eulerian Mesh. Although this method is not specifically designed for topology optimization, it can easily handle topology changes. However, the resulting optimal shape is strongly dependent on the initial guess.
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a level set method for shape optimization
Comptes Rendus Mathematique, 2002Co-Authors: Gregoire Allaire, François Jouve, Ancamaria ToaderAbstract:We study a level-set method for numerical shape optimization of elastic structures. Our approach combines the level-set algorithm of Osher and Sethian with the classical shape gradient. Although this method is not specifically designed for topology optimization, it can easily handle topology changes for a very large class of objective functions. Its cost is moderate since the shape is captured on a fixed Eulerian Mesh. To cite this article: G. Allaire et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 1125–1130.
Deborah Sulsky - One of the best experts on this subject based on the ideXlab platform.
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fluid membrane interaction based on the material point method
International Journal for Numerical Methods in Engineering, 2000Co-Authors: Allen R York, Deborah Sulsky, H L SchreyerAbstract:The material point method (MPM) uses unconnected, Lagrangian, material points to discretize solids, fluids or membranes. All variables in the solution of the continuum equations are associated with these points; so, for example, they carry mass, velocity, stress and strain. A background Eulerian Mesh is used to solve the momentum equation. Data mapped from the material points are used to initialize variables on the background Mesh. In the case of multiple materials, the stress from each material contributes to forces at nearby Mesh points, so the solution of the momentum equation includes all materials. The Mesh solution then updates the material point values. This simple algorithm treats all materials in a uniform way, avoids complicated Mesh construction and automatically applies a noslip contact algorithm at no additional cost. Several examples are used to demonstrate the method, including simulation of a pressurized membrane and the impact of a probe with a pre-inflated airbag. Copyright © 2000 John Wiley & Sons, Ltd.
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axisymmetric form of the material point method with applications to upsetting and taylor impact problems
Computer Methods in Applied Mechanics and Engineering, 1996Co-Authors: Deborah Sulsky, H L SchreyerAbstract:Abstract The material point method is an evolution of particle-in-cell methods which utilize two Meshes, one a material or Lagrangian Mesh defined over material of the body under consideration, and the second a spatial or Eulerian Mesh defined over the computational domain. Although Meshes are used, they have none of the negative aspects normally associated with conventional Eulerian or Lagrangian approaches. The advantages of both the Eulerian and Lagrangian methods are achieved by using the appropriate frame for each aspect of the computation, with a mapping between the two Meshes that is performed at each step in the loading process. The numerical dissipation normally displayed by an Eulerian method because of advection is avoided by using a Lagrangian step; the Mesh distortion associated with the Lagrangian method is prevented by mapping to a user-controlled Mesh. Furthermore, explicit material points can be tracked through the process of deformation, thereby alleviating the need to map history variables. As a consequence, problems which have caused severe numerical difficulties with conventional methods are handled fairly routinely. Examples of such problems are the upsetting of billets and the Taylor problem of cylinders impacting a rigid wall. Numerical solutions to these problems are obtained with the material point method and where possible comparisons with experimental data and existing numerical solutions are presented.
Allen R York - One of the best experts on this subject based on the ideXlab platform.
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fluid membrane interaction based on the material point method
International Journal for Numerical Methods in Engineering, 2000Co-Authors: Allen R York, Deborah Sulsky, H L SchreyerAbstract:The material point method (MPM) uses unconnected, Lagrangian, material points to discretize solids, fluids or membranes. All variables in the solution of the continuum equations are associated with these points; so, for example, they carry mass, velocity, stress and strain. A background Eulerian Mesh is used to solve the momentum equation. Data mapped from the material points are used to initialize variables on the background Mesh. In the case of multiple materials, the stress from each material contributes to forces at nearby Mesh points, so the solution of the momentum equation includes all materials. The Mesh solution then updates the material point values. This simple algorithm treats all materials in a uniform way, avoids complicated Mesh construction and automatically applies a noslip contact algorithm at no additional cost. Several examples are used to demonstrate the method, including simulation of a pressurized membrane and the impact of a probe with a pre-inflated airbag. Copyright © 2000 John Wiley & Sons, Ltd.
