The Experts below are selected from a list of 7665 Experts worldwide ranked by ideXlab platform
Michael Yu Wang - One of the best experts on this subject based on the ideXlab platform.
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level set based Structural Topology Optimization for minimizing frequency response
Journal of Sound and Vibration, 2011Co-Authors: Lei Shu, Michael Yu Wang, Zongde Fang, Peng WeiAbstract:Abstract For the purpose of structure vibration reduction, a Structural Topology Optimization for minimizing frequency response is proposed based on the level set method. The objective of the present study is to minimize the frequency response at the specified points or surfaces on the structure with an excitation frequency or a frequency range, subject to the given amount of the material over the admissible design domain. The sensitivity analysis with respect to the Structural boundaries is carried out, while the Extended finite element method (X-FEM) is employed for solving the state equation and the adjoint equation. The optimal structure with smooth boundaries is obtained by the level set evolution with advection velocity, derived from the sensitivity analysis and the Optimization algorithm. A number of numerical examples, in the frameworks of two-dimension (2D) and three-dimension (3D), are presented to demonstrate the feasibility and effectiveness of the proposed approach.
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Structural Topology Optimization for Forced Vibration Problem Using Level Set Method
Volume 5: 37th Design Automation Conference Parts A and B, 2011Co-Authors: Lei Shu, Michael Yu Wang, Zongde FangAbstract:For the purpose of structure vibration reduction, a Structural Topology Optimization for forced vibration problem is proposed based on the level set method. The objective of present study is to minimize the frequency response at the specified points or surfaces on the structure with an excitation frequency or a frequency range, subject to the given amount of the material over the admissible design domain. The sensitivity analysis with respect to the Structural boundaries is carried out, while the X-FEM is employed for solving the state equation and the adjoint equation. The optimal structure with smooth boundaries is obtained by the level set evolution with advection velocity, derived from the sensitivity analysis and the Optimization algorithm. A number of two-dimensional numerical examples are presented to demonstrate the feasibility and effectiveness of the proposed approach.Copyright © 2011 by ASME
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piecewise constant level set method for Structural Topology Optimization
International Journal for Numerical Methods in Engineering, 2009Co-Authors: Michael Yu WangAbstract:In this paper, a piecewise constant level set (PCLS) method is implemented to solve a Structural shape and Topology Optimization problem. In the classical level set method, the geometrical boundary of the structure under Optimization is represented by the zero level set of a continuous level set function, e.g. the signed distance function. Instead, in the PCLS approach the boundary is described by discontinuities of PCLS functions. The PCLS method is related to the phase-field methods, and the Topology Optimization problem is defined as a minimization problem with piecewise constant constraints, without the need of solving the Hamilton-Jacobi equation. The result is not moving the boundaries during the iterative procedure. Thus, it offers some advantages in treating geometries, eliminating the reinitialization and naturally nucleating holes when needed. In the paper, the PCLS method is implemented with the additive operator splitting numerical scheme, and several numerical and procedural issues of the implementation are discussed. Examples of 2D Structural Topology Optimization problem of minimum compliance design are presented, illustrating the effectiveness of the proposed method.
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radial basis functions and level set method for Structural Topology Optimization
International Journal for Numerical Methods in Engineering, 2006Co-Authors: Shengyin Wang, Michael Yu WangAbstract:Level set methods have become an attractive design tool in shape and Topology Optimization for obtaining lighter and more efficient structures. In this paper, the popular radial basis functions (RBFs) in scattered data fitting and function approximation are incorporated into the conventional level set methods to construct a more efficient approach for Structural Topology Optimization. RBF implicit modelling with multiquadric (MQ) splines is developed to define the implicit level set function with a high level of accuracy and smoothness. A RBF-level set Optimization method is proposed to transform the Hamilton-Jacobi partial differential equation (PDE) into a system of ordinary differential equations (ODEs) over the entire design domain by using a collocation formulation of the method of lines. With the mathematical convenience, the original time dependent initial value problem is changed to an interpolation problem for the initial values of the generalized expansion coefficients. A physically meaningful and efficient extension velocity method is presented to avoid possible problems without reinitialization in the level set methods. The proposed method is implemented in the framework of minimum compliance design that has been extensively studied in Topology Optimization and its efficiency and accuracy over the conventional level set methods are highlighted. Numerical examples show the success of the present RBF-level set method in the accuracy, convergence speed and insensitivity to initial designs in Topology Optimization of two-dimensional (2D) structures. It is suggested that the introduction of the radial basis functions to the level set methods can be promising in Structural Topology Optimization.
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A moving superimposed finite element method for Structural Topology Optimization
International Journal for Numerical Methods in Engineering, 2006Co-Authors: Shengyin Wang, Michael Yu WangAbstract:Level set methods are becoming an attractive design tool in shape and Topology Optimization for obtaining efficient and lighter structures. In this paper, a dynamic implicit boundary-based moving superimposed finite element method (s-version FEM or S-FEM) is developed for Structural Topology Optimization using the level set methods, in which the variational interior and exterior boundaries are represented by the zero level set. Both a global mesh and an overlaying local mesh are integrated into the moving S-FEM analysis model. A relatively coarse fixed Eulerian mesh consisting of bilinear rectangular elements is used as a global mesh. The local mesh consisting of flexible linear triangular elements is constructed to match the dynamic implicit boundary captured from nodal values of the implicit level set function. In numerical integration using the Gauss quadrature rule, the practical difficulty due to the discontinuities is overcome by the coincidence of the global and local meshes. A double mapping technique is developed to perform the numerical integration for the global and coupling matrices of the overlapped elements with two different co-ordinate systems. An element killing strategy is presented to reduce the total number of degrees of freedom to improve the computational efficiency. A simple constraint handling approach is proposed to perform minimum compliance design with a volume constraint. A physically meaningful and numerically efficient velocity extension method is developed to avoid the complicated PDE solving procedure. The proposed moving S-FEM is applied to Structural Topology Optimization using the level set methods as an effective tool for the numerical analysis of the linear elasticity Topology Optimization problems. For the classical elasticity problems in the literature, the present S-FEM can achieve numerical results in good agreement with those from the theoretical solutions and/or numerical results from the standard FEM. For the minimum compliance Topology Optimization problems in Structural Optimization, the present approach significantly outperforms the well-recognized ‘ersatz material’ approach as expected in the accuracy of the strain field, numerical stability, and representation fidelity at the expense of increased computational time. It is also shown that the present approach is able to produce structures near the theoretical optimum. It is suggested that the present S-FEM can be a promising tool for shape and Topology Optimization using the level set methods. Copyright © 2005 John Wiley & Sons, Ltd.
Colby C. Swan - One of the best experts on this subject based on the ideXlab platform.
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A Q4/Q4 continuum Structural Topology Optimization implementation
Structural and Multidisciplinary Optimization, 2004Co-Authors: Salam Rahmatalla, Colby C. SwanAbstract:A node-based design variable implementation for continuum Structural Topology Optimization in a finite element framework is presented and its properties are explored in the context of solving a number of different design examples. Since the implementation ensures C0continuity of design variables, it is immune to element-wise checkerboarding instabilities that are a concern with element-based design variables. Nevertheless, in a subset of design examples considered, especially those involving compliance minimization with coarse meshes, the implementation is found to introduce a new phenomenon that takes the form of “layering” or “islanding” in the material layout design. In the examples studied, this phenomenon disappears with mesh refinement or the enforcement of sufficiently restrictive design perimeter constraints, the latter sometimes being necessary in design problems involving bending to ensure convergence with mesh refinement. Based on its demonstrated performance characteristics, the authors conclude that the proposed node-based implementation is viable for continued usage in continuum Topology Optimization.
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a q4 q4 continuum Structural Topology Optimization implementation
Structural and Multidisciplinary Optimization, 2004Co-Authors: Salam Rahmatalla, Colby C. SwanAbstract:A node-based design variable implementation for continuum Structural Topology Optimization in a finite element framework is presented and its properties are explored in the context of solving a number of different design examples. Since the implementation ensures C0continuity of design variables, it is immune to element-wise checkerboarding instabilities that are a concern with element-based design variables. Nevertheless, in a subset of design examples considered, especially those involving compliance minimization with coarse meshes, the implementation is found to introduce a new phenomenon that takes the form of “layering” or “islanding” in the material layout design. In the examples studied, this phenomenon disappears with mesh refinement or the enforcement of sufficiently restrictive design perimeter constraints, the latter sometimes being necessary in design problems involving bending to ensure convergence with mesh refinement. Based on its demonstrated performance characteristics, the authors conclude that the proposed node-based implementation is viable for continued usage in continuum Topology Optimization.
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Sparse Monolithic Compliant Mechanisms Using Continuum Structural Topology Optimization
Volume 2: 28th Biennial Mechanisms and Robotics Conference Parts A and B, 2004Co-Authors: Salam Rahmatalla, Colby C. SwanAbstract:A formulation for design of continuous, hinge-free compliant mechanisms is developed and examined within a continuum Structural Topology Optimization framework. The proposed formulation involves solving two nested Optimization problems. In the inner problem the arrangement of a constrained amount of Structural material is optimized to maximize the mechanism’s mutual potential energy in response to a force loading at the input port while working against artificial springs on the input and output ports. As the relative stiffness of the artificial springs increases, the material continuity of the mechanism also increases to the point where de facto “hinge” regions are eliminated. In the outer problem, one solves for an appropriate amount of Structural material that yields the desired compliance characteristics of the mechanism when working against the workpiece resistance. Different aspects of the proposed formulation are demonstrated on a number of examples and discussed.Copyright © 2004 by ASME
Chun-yi Lin - One of the best experts on this subject based on the ideXlab platform.
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A binary particle swarm Optimization for continuum Structural Topology Optimization
Applied Soft Computing, 2011Co-Authors: Guan-chun Luh, Chun-yi Lin, Yu-shu LinAbstract:The particle swarm Optimization (PSO) algorithm, a relatively recent bio-inspired approach to solve combinatorial Optimization problems mimicking the social behavior of birds flocking, is applied to problems of continuum Structural Topology design for the purpose of investigating optimal topologies and automatically creating innovative solutions. An overview of the PSO and binary PSO algorithms are first described. A discretized Topology design representation and the method for mapping binary particle into this representation are then detailed. Subsequently, a modified binary PSO algorithm that adopts the concept of genotype-phenotype representation is illustrated. Several well-studied examples from Structural Topology Optimization problems of minimum weight and minimum compliance are used to demonstrate its efficiency and versatility. The results indicate the effectiveness of the proposed algorithm and its ability to find families of Structural topologies.
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A Binary Particle Swarm Optimization for Structural Topology Optimization
2010 Third International Joint Conference on Computational Science and Optimization, 2010Co-Authors: Guan-chun Luh, Chun-yi LinAbstract:Binary particle swarm Optimization (BPSO) algorithm is applied to continuum Structural Topology design. An overview of the PSO and binary PSO algorithms are first described. A discretized Topology design representation and the method for mapping each binary particle into toplogy representation are then detailed. Subsequently, a modified BPSO algorithm adopting binary bit-string type code and logic AND, OR and XOR operators with corresponding updating rules is illustrated. A well-studied example from Structural Topology Optimization problems is utilized to demonstrate the efficiency and versatility of the proposed method. The results indicate the effectiveness of the proposed algorithm and its ability to find families of Structural topologies.
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Structural Topology Optimization using ant colony Optimization algorithm
Applied Soft Computing, 2009Co-Authors: Guan-chun Luh, Chun-yi LinAbstract:The ant colony Optimization (ACO) algorithm, a relatively recent bio-inspired approach to solve combinatorial Optimization problems mimicking the behavior of real ant colonies, is applied to problems of continuum Structural Topology design. An overview of the ACO algorithm is first described. A discretized Topology design representation and the method for mapping ant's trail into this representation are then detailed. Subsequently, a modified ACO algorithm with elitist ants, niche strategy and memory of multiple colonies is illustrated. Several well-studied examples from Structural Topology Optimization problems of minimum weight and minimum compliance are used to demonstrate its efficiency and versatility. The results indicate the effectiveness of the proposed algorithm and its ability to find families of multi-modal optimal design.
Guan-chun Luh - One of the best experts on this subject based on the ideXlab platform.
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A binary particle swarm Optimization for continuum Structural Topology Optimization
Applied Soft Computing, 2011Co-Authors: Guan-chun Luh, Chun-yi Lin, Yu-shu LinAbstract:The particle swarm Optimization (PSO) algorithm, a relatively recent bio-inspired approach to solve combinatorial Optimization problems mimicking the social behavior of birds flocking, is applied to problems of continuum Structural Topology design for the purpose of investigating optimal topologies and automatically creating innovative solutions. An overview of the PSO and binary PSO algorithms are first described. A discretized Topology design representation and the method for mapping binary particle into this representation are then detailed. Subsequently, a modified binary PSO algorithm that adopts the concept of genotype-phenotype representation is illustrated. Several well-studied examples from Structural Topology Optimization problems of minimum weight and minimum compliance are used to demonstrate its efficiency and versatility. The results indicate the effectiveness of the proposed algorithm and its ability to find families of Structural topologies.
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A Binary Particle Swarm Optimization for Structural Topology Optimization
2010 Third International Joint Conference on Computational Science and Optimization, 2010Co-Authors: Guan-chun Luh, Chun-yi LinAbstract:Binary particle swarm Optimization (BPSO) algorithm is applied to continuum Structural Topology design. An overview of the PSO and binary PSO algorithms are first described. A discretized Topology design representation and the method for mapping each binary particle into toplogy representation are then detailed. Subsequently, a modified BPSO algorithm adopting binary bit-string type code and logic AND, OR and XOR operators with corresponding updating rules is illustrated. A well-studied example from Structural Topology Optimization problems is utilized to demonstrate the efficiency and versatility of the proposed method. The results indicate the effectiveness of the proposed algorithm and its ability to find families of Structural topologies.
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Structural Topology Optimization using ant colony Optimization algorithm
Applied Soft Computing, 2009Co-Authors: Guan-chun Luh, Chun-yi LinAbstract:The ant colony Optimization (ACO) algorithm, a relatively recent bio-inspired approach to solve combinatorial Optimization problems mimicking the behavior of real ant colonies, is applied to problems of continuum Structural Topology design. An overview of the ACO algorithm is first described. A discretized Topology design representation and the method for mapping ant's trail into this representation are then detailed. Subsequently, a modified ACO algorithm with elitist ants, niche strategy and memory of multiple colonies is illustrated. Several well-studied examples from Structural Topology Optimization problems of minimum weight and minimum compliance are used to demonstrate its efficiency and versatility. The results indicate the effectiveness of the proposed algorithm and its ability to find families of multi-modal optimal design.
Salam Rahmatalla - One of the best experts on this subject based on the ideXlab platform.
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A Q4/Q4 continuum Structural Topology Optimization implementation
Structural and Multidisciplinary Optimization, 2004Co-Authors: Salam Rahmatalla, Colby C. SwanAbstract:A node-based design variable implementation for continuum Structural Topology Optimization in a finite element framework is presented and its properties are explored in the context of solving a number of different design examples. Since the implementation ensures C0continuity of design variables, it is immune to element-wise checkerboarding instabilities that are a concern with element-based design variables. Nevertheless, in a subset of design examples considered, especially those involving compliance minimization with coarse meshes, the implementation is found to introduce a new phenomenon that takes the form of “layering” or “islanding” in the material layout design. In the examples studied, this phenomenon disappears with mesh refinement or the enforcement of sufficiently restrictive design perimeter constraints, the latter sometimes being necessary in design problems involving bending to ensure convergence with mesh refinement. Based on its demonstrated performance characteristics, the authors conclude that the proposed node-based implementation is viable for continued usage in continuum Topology Optimization.
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a q4 q4 continuum Structural Topology Optimization implementation
Structural and Multidisciplinary Optimization, 2004Co-Authors: Salam Rahmatalla, Colby C. SwanAbstract:A node-based design variable implementation for continuum Structural Topology Optimization in a finite element framework is presented and its properties are explored in the context of solving a number of different design examples. Since the implementation ensures C0continuity of design variables, it is immune to element-wise checkerboarding instabilities that are a concern with element-based design variables. Nevertheless, in a subset of design examples considered, especially those involving compliance minimization with coarse meshes, the implementation is found to introduce a new phenomenon that takes the form of “layering” or “islanding” in the material layout design. In the examples studied, this phenomenon disappears with mesh refinement or the enforcement of sufficiently restrictive design perimeter constraints, the latter sometimes being necessary in design problems involving bending to ensure convergence with mesh refinement. Based on its demonstrated performance characteristics, the authors conclude that the proposed node-based implementation is viable for continued usage in continuum Topology Optimization.
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Sparse Monolithic Compliant Mechanisms Using Continuum Structural Topology Optimization
Volume 2: 28th Biennial Mechanisms and Robotics Conference Parts A and B, 2004Co-Authors: Salam Rahmatalla, Colby C. SwanAbstract:A formulation for design of continuous, hinge-free compliant mechanisms is developed and examined within a continuum Structural Topology Optimization framework. The proposed formulation involves solving two nested Optimization problems. In the inner problem the arrangement of a constrained amount of Structural material is optimized to maximize the mechanism’s mutual potential energy in response to a force loading at the input port while working against artificial springs on the input and output ports. As the relative stiffness of the artificial springs increases, the material continuity of the mechanism also increases to the point where de facto “hinge” regions are eliminated. In the outer problem, one solves for an appropriate amount of Structural material that yields the desired compliance characteristics of the mechanism when working against the workpiece resistance. Different aspects of the proposed formulation are demonstrated on a number of examples and discussed.Copyright © 2004 by ASME
