Zhen Luo¹, Nong Zhang¹, Tao Wu^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.4, pp. 299-328, 2012, DOI:10.3970/cmes.2012.085.299

Abstract This paper presents a meshless Galerkin level-set method (MGLSM) for shape and topology optimization of compliant mechanisms of geometrically nonlinear structures. The design boundary of the mechanism is implicitly described as the zero level set of a Lipschitz continuous level set function of higher dimension. The moving least square (MLS) approximation is used to construct the meshless shape functions with the global Galerkin weak-form in terms of a set of arbitrarily distributed nodes. The MLS shape function is first employed to parameterize the level set function via the surface fitting rather than interpolation, and then used to implement the meshless… More >

Yu Wang¹, Zhen Luo^1,2, Nong Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.3, pp. 229-252, 2012, DOI:10.3970/cmes.2012.084.229

Abstract This paper proposes an alternative topology optimization method for the optimal design of continuum structures, which involves a multilevel nodal density-based approximant based on the concept of conventional SIMP (solid isotropic material with penalization) model. First, in terms of the original set of nodal densities, the Shepard function method is applied to generate a non-local nodal density field with enriched smoothness over the design domain. The new nodal density field possesses non-negative and range-bounded properties to ensure a physically meaningful approximation of topology optimization design. Second, the density variables at the nodes of finite elements are used to interpolate elemental… More >

Zhen Luo^1,2, Nong Zhang^1,3, Yu Wang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.1, pp. 73-96, 2012, DOI:10.3970/cmes.2012.083.073

Abstract This paper aims to present a physically meaningful level set method for shape and topology optimization of structures. Compared to the conventional level set method which represents the design boundary as the zero level set, in this study the boundary is embedded into non-zero constant level sets of the level set function, to implicitly implement shape fidelity and topology changes in time via the propagation of the discrete level set function. A point-wise nodal density field, non-negative and value-bounded, is used to parameterize the level set function via the compactly supported radial basis functions (CSRBFs) at a uniformly defined set… More >

Mohsen Sadeghbeigi Olyaie¹, Mohammad Reza Razfar², Semyung Wang³, Edward J. Kansa⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.1, pp. 55-82, 2011, DOI:10.32604/cmes.2011.082.055

Abstract This paper presents the topology optimization design for a linear micromotor, including multitude cantilever piezoelectric bimorphs. Each microbeam in the mechanism can be actuated in both axial and flexural modes simultaneously. For this design, we consider quasi-static and linear conditions, and the smoothed finite element method (S-FEM) is employed in the analysis of piezoelectric effects. Certainty variables such as weight of the structure and equilibrium equations are considered as constraints during the topology optimization design process, then a deterministic topology optimization (DTO) is conducted. To avoid the overly stiff behavior in FEM modeling, a relatively new numerical method known as… More >

T. Matsumoto¹, T. Yamada¹, T. Takahashi¹, C.J. Zheng², S. Harada¹

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.2, pp. 77-94, 2011, DOI:10.3970/cmes.2011.078.077

Abstract Shape design and topology sensitivity formulations for acoustic problems based on adjoint method and the boundary element method are presented and are applied to shape sensitivity analysis and topology optimization of acoustic field. The objective function is assumed to consist only of boundary integrals and quantities defined at certain number of discrete points. The adjoint field is defined so that the sensitivity of the objective function does not include the unknown sensitivity coefficients of the sound pressures and particle velocities on the boundary and in the domain. Since the final sensitivity expression does not have the sensitivity coefficients of the… More >

S.L. Li^1,2, S.Y. Long¹, G.Y. Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.60, No.1, pp. 73-94, 2010, DOI:10.3970/cmes.2010.060.073

Abstract A new implementation of topology optimization for the plate described by the Reissner-Mindlin theory based on the meshless natural neighbour Petrov-Galerkin method (NNPG) is proposed in this work. The objective is to produce the stiffest plate for a given volume by redistributing the material throughout the plate. We try to couple the advantages of the meshless numerical method with the topology optimization of moderately thick plate. The numerical approach presented here is based on the solid isotropic material with penalization (SIMP) formulation of the topology optimization problem. The natural neighbour interpolation shape function is employed to discretize both displacement and… More >

R. Zakhama^1,2,3, M.M. Abdalla², H. Smaoui^1,3, Z. Gürdal²

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.1, pp. 1-26, 2009, DOI:10.3970/cmes.2009.051.001

Abstract A multigrid accelerated cellular automata algorithm for two and three dimensional continuum topology optimization problems is presented. The topology optimization problem is regularized using the traditional SIMP approach. The analysis rules are derived from the principle of minimum total potential energy, and the design rules are derived based on continuous optimality criteria interpreted as local Kuhn-Tucker conditions. Three versions of the algorithm are implemented; a cellular automata based design algorithm, a baseline multigrid algorithm for analysis acceleration and a full multigrid integrated analysis and design algorithm. It is shown that the multigrid accelerated cellular automata scheme is a powerful tool… More >

Juan Zheng^1,2,3, Shuyao Long^1,2, Yuanbo Xiong^1,2, Guangyao Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.1, pp. 19-34, 2009, DOI:10.3970/cmes.2009.042.019

Abstract In this paper, the finite volume meshless local Petrov-Galerkin method (FVMLPG) is applied to carry out a topology optimization design for the continuum structures. In FVMLPG method, the finite volume method is combined with the meshless local Petrov-Galekin method, and both strains as well as displacements are independently interpolated, at randomly distributed points in a local domain, using the moving least squares (MLS) approximation. The nodal values of strains are expressed in terms of the independently interpolated nodal values of displacements, by simple enforcing the strain-displacement relationships directly. Considering the relative density of nodes as design variable, and the minimization… More >

Shu Li¹, S. N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.1, pp. 37-56, 2008, DOI:10.3970/cmes.2008.030.037

Abstract In this paper, a method based on a combination of an optimization of directions of orthotropy, along with topology optimization, is applied to continuum orthotropic solids with the objective of minimizing their compliance. The spatial discretization algorithm is the so called Meshless Local Petrov-Galerkin (MLPG) "mixed collocation'' method for the design domain, and the material-orthotropy orientation angles and the nodal volume fractions are used as the design variables in material optimization and topology optimization, respectively. Filtering after each iteration diminishes the checkerboard effect in the topology optimization problem. The example results are provided to illustrate the effects of the orthotropic… More >

Shu Li¹, S. N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.1, pp. 61-74, 2008, DOI:10.3970/cmes.2008.026.061

Abstract The Meshless Local Petrov-Galerkin (MLPG) "mixed collocation'' method is applied to the problem of topology-optimization of elastic structures. In this paper, the topic of compliance minimization of elastic structures is pursued, and nodal design variables which represent nodal volume fractions at discretized nodes are adopted. A so-called nodal sensitivity filter is employed, to prevent the phenomenon of checkerboarding in numerical solutions to the topology-optimization problems. The example results presented in the paper demonstrate the suitability and versatility of the MLPG "mixed collocation'' method, in implementing structural topology-optimization. More >