Smooth Boundary Topology Optimization for Electrostatic Problems Through the Combination of Shape and Topological Design Sensitivities

2008 ◽  
Vol 44 (6) ◽  
pp. 1002-1005 ◽  
Author(s):  
Dong-Hun Kim ◽  
Soo Bum Lee ◽  
Byung Man Kwank ◽  
Heung-Geun Kim ◽  
D.A. Lowther
2019 ◽  
Vol 16 (08) ◽  
pp. 1850116 ◽  
Author(s):  
Mi Xiao ◽  
Sheng Chu ◽  
Liang Gao ◽  
Hao Li

In this study, a hybrid method for density-related topology optimization is proposed, which consists of two parts: the discrete level-set method (LSM) based on solid isotropic material with penalization (SIMP) and the structural boundary extraction method based on support vector machine (SVM). In the hybrid method, the SIMP method is implemented to create new holes which are inserted into the topological structure obtained by the discrete LSM. SVM is utilized for extracting the boundary of the structure obtained by the SIMP-based discrete LSM. Based on the clear boundary extracted by SVM, a smooth boundary can be further obtained after data filtering. Four numerical examples are used to test the advantages of the hybrid method.


2020 ◽  
pp. 107754632096398
Author(s):  
Bin Xu ◽  
Yuanhao Liu ◽  
Jingdan Xue ◽  
Yonghui Zhao

A two-scale concurrent topology optimization method based on the couple stress theory is proposed for maximizing structural fundamental eigenfrequency. Because of the fact that the classical mechanics theory cannot reveal the size effect because of neglecting the influence of microstructure, the theory of couple stress including the microscopic properties of materials can be used to describe the size effect in deformations. On the foundation of the couple stress theory, the two-scale optimization model for finding optimal configurations of macrostructures and their periodic composite material microstructures is built. And the fundamental eigenfrequency of the macrostructure is maximized. The effective macroscopic couple stress constitutive constants of macrostructures are calculated by the representative volume element method. And a modified solid isotropic material with a penalization model is used to effectively avoid the localized mode. The optimization algorithm based on the bidirectional evolutionary structural optimization method is proposed. The optimal results of numerical examples show that the optimal topologies and natural frequencies obtained by the couple stress theory may differ significantly from those obtained by the typical Cauchy theory. It is obvious that couple stress theory can effectively describe the size effect in topology optimization.


2019 ◽  
Vol 36 (1) ◽  
pp. 126-146 ◽  
Author(s):  
Daicong Da ◽  
Xiangyang Cui ◽  
Kai Long ◽  
Yong Cai ◽  
Guangyao Li

PurposeThe optimal material microstructures in pure material design are no longer efficient or optimal when accounting macroscopic structure performance with specific boundary conditions. Therefore, it is important to provide a novel multiscale topology optimization framework to tailor the topology of structure and the material to achieve specific applications. In comparison with porous materials, composites consisting of two or more phase materials are more attractive and advantageous from the perspective of engineering application. This paper aims to provide a novel concurrent topological design of structures and microscopic materials for thermal conductivity involving multi-material topology optimization (material distribution) at the lower scale.Design/methodology/approachIn this work, the effective thermal conductivity properties of microscopic three or more phase materials are obtained via homogenization theory, which serves as a bridge of the macrostructure and the periodic material microstructures. The optimization problem, including the topological design of macrostructures and inverse homogenization of microscopic materials, are solved by bi-directional evolutionary structure optimization method.FindingsAs a result, the presented framework shows high stability during the optimization process and requires little iterations for convergence. A number of interesting and valid macrostructures and material microstructures are obtained in terms of optimal thermal conductive path, which verify the effectiveness of the proposed mutliscale topology optimization method. Numerical examples adequately consider effects of initial guesses of the representative unit cell and of the volume constraints of adopted base materials at the microscopic scale on the final design. The resultant structures at both the scales with clear and distinctive boundary between different phases, making the manufacturing straightforward.Originality/valueThis paper presents a novel multiscale concurrent topology optimization method for structures and the underlying multi-phase materials for thermal conductivity. The authors have carried out the concurrent multi-phase topology optimization for both 2D and 3D cases, which makes this work distinguished from existing references. In addition, some interesting and efficient multi-phase material microstructures and macrostructures have been obtained in terms of optimal thermal conductive path.


2021 ◽  
pp. 1-25
Author(s):  
Pai Liu ◽  
Xiaopeng Zhang ◽  
Yangjun Luo

Abstract The topological design of structures to avoid vibration resonance for a certain external excitation frequency is often desired. This paper considers the topology optimization of freely vibrating bi-material structures with fixed/varying attached mass positions, targeting at maximizing the frequency band gap centering at a specified frequency. A band gap measure index is proposed to measure the size of the band gap with a specified center frequency. Aiming at maximizing this measure index, the topology optimization problem is formulated on the basis of the material-field series-expansion (MFSE) method, which greatly reduces the number of design variables and at the same time keeps the capability to describe relatively complex structural topologies with clear boundaries. As the considered optimization problem is highly non-linear and may yield multiple local minima, a sequential Kriging-based optimization solution strategy is employed to effectively solve the optimization problem. This solution strategy exhibits a relatively strong global search capability and requires no sensitivity information. With the present topology optimization model and the gradient-free algorithm, relative large band gaps with specified center frequencies have been obtained for 2D beams and 3D plates, without specifying the frequency orders between which the desired band gap occurs in prior.


2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fengfeng Wang ◽  
Guolai Yang

In this work, the topology optimization of a mortar base plate is analysed under impact loading conditions. Usually, in this case, only ordinary topology optimization under volume constraints is considered. However, to reduce the quality of the mortar base plate and facilitate engineering applications, the topological optimization problem of the continuum of the base plate under the engineering and quality constraint is considered. A finite element model has been established and verified by testing for the mortar base plate. The variable density method was used to obtain the topological optimization results of the base plate based on the force transmission path, and then the structure was reconstructed. The mass of the optimization model of the base plate is 12.78% lower than that of the original model. In comparison with the original base plate before optimization, the results show that the maximum deformation and stress of the base plate decreased by 16.85% and 35.52%, respectively. Also, the firing stability of the mortar meets requirements, which not only meet the design requirement but also provide a reference for the performance improvement and structural optimization design of the base plate.


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