The Experts below are selected from a list of 18108 Experts worldwide ranked by ideXlab platform
Xiaodong Huang - One of the best experts on this subject based on the ideXlab platform.
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Concurrent optimization of Macrostructures and material microstructures and orientations for maximizing natural frequency
Engineering Structures, 2020Co-Authors: Xiaolei Yan, Haiyan Hua, Weidong Huang, Xiaodong HuangAbstract:Abstract In this paper, an efficient concurrent optimization method of Macrostructures, and material microstructures and orientations is proposed for maximizing natural frequency. It is assumed that the Macrostructure is composed of uniform material with the same microstructure but with various orientation. The bi-directional evolutionary structural optimization (BESO) method is applied to optimize the Macrostructure and its material microstructure under a given weight constraint. Meanwhile, the optimality condition with respect to local material orientation is derived and embedded in the two-scale design of Macrostructures and material microstructures. Numerical examples are presented to demonstrate the capability and effectiveness of the proposed optimization algorithm. The results show that the current design of Macrostructures, material microstructures, and local material orientation greatly improves structural dynamic performance.
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concurrent topology optimization of Macrostructures and material microstructures for natural frequency
Materials & Design, 2016Co-Authors: Ricky W.k. Chan, Xiaodong HuangAbstract:Based on the bi-direction evolutionary structural optimization (BESO) method, a concurrent two-scale topology optimization algorithm is proposed for maximizing natural frequency of structures. The macro-scale structure is assumed to be constructed with a composite material, whose microstructure is represented by periodic unit cells (PUC). This optimization scheme aims to obtain the optimal topologies of the structure at the macro-scale level and microstructure of its material at the micro scale simultaneously, so that the resulting structure with a given weight has maximum natural frequency. The effective properties of a composite material with representative PUC are homogenized and integrated into the frequency analysis of the Macrostructure. To implement topology optimization at both scales, the design variables are assigned for both the Macrostructure and microstructure of its material. The sensitivity analysis with regard to the variation of design variables is conducted for iteratively updating the topologies at both scales synchronously. Numerical 2D and 3D examples are presented to demonstrate the validity of the proposed concurrent optimization algorithm for frequency optimization problems.
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concurrent topological design of composite thermoelastic Macrostructure and microstructure with multi phase material for maximum stiffness
Composite Structures, 2016Co-Authors: Bin Xu, Xiaodong Huang, Shiwei ZhouAbstract:A method for the multi-scale design of composite thermoelastic Macrostructure and periodic microstructure with multi-phase materials is proposed. A concurrent topology optimization model of Macrostructure and microstructure is established, where the objective is to maximize the macrostructural stiffness subject to volume constraints on the macro-material distribution and phase materials. Based on the material interpolation scheme of the solid isotropic material with penalization (SIMP), the sensitivity of the mean compliance of the composite Macrostructure with respect to design variables on two scales, i.e., macro and micro scales, is derived. The optimization problem is solved using a bi-directional evolutionary structural optimization (BESO) method and the corresponding optimization procedure for the concurrent topology optimization is proposed. Several examples are presented to demonstrate the effectiveness of the proposed method.
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Comparing optimal material microstructures with optimal periodic structures
Computational Materials Science, 2013Co-Authors: Xiaodong Huang, Xiaoying Yang, Jian Hua RongAbstract:The optimal design of periodic structures under the macro scale and that of periodic materials under the micro scale are treated differently by the current topology optimization techniques. Nevertheless, a material point in theory could be considered as a unit cell in a periodic structure if the number of unit cells approaches to infinity. In this work, we investigate the equivalence between optimal solutions of periodic structures obtained from the macro scale approach on the structure level and those of material microstructures obtained from the micro scale approach using the homogenization techniques. The minimization of the mean compliance of the Macrostructure with a volume constraint is taken as the optimization problem for both structural and material designs. On the macro scale, we solve the optimization problem by gradually increasing the number of unit cells until the solution converges, in terms of both the topology and the objective function. On the micro scale, the optimal microstructure of the material is obtained for the Macrostructure under prescribed loading and support conditions. The microstructure of the material compares very well with the corresponding optimal topology from the periodic macrostructural design. This work reveals the equivalence of the solutions from the macro and micro approaches, and proves that an optimal finite periodic solution remains valid through cell refinement to infinite periodicity.
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Topology optimization of microstructures of cellular materials and composites for Macrostructures
Computational Materials Science, 2013Co-Authors: Xiaodong Huang, Shiwei Zhou, Yi Min XieAbstract:This paper introduces a topology optimization algorithm for the optimal design of cellular materials and composites with periodic microstructures so that the resulting Macrostructure has the maximum stiffness (or minimum mean compliance). The effective properties of the heterogeneous material are obtained through the homogenization theory, and these properties are integrated into the analysis of the Macrostructure. The sensitivity analysis for the material unit cell is established for such a two-scale optimization problem. Then, a bi-directional evolutionary structural optimization (BESO) approach is developed to achieve a clear and optimized topology for the material microstructure. Several numerical examples are presented to validate the proposed optimization algorithm and a variety of anisotropic microstructures of cellular materials and composites are obtained. The various effects on the topological design of the material microstructure are discussed.
Yi Min Xie - One of the best experts on this subject based on the ideXlab platform.
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concurrent design of composite Macrostructure and cellular microstructure under random excitations
Composite Structures, 2015Co-Authors: Yi Min XieAbstract:In this paper, a method for the concurrent topology optimization of macrostructural material distribution and periodic microstructure under random excitations is proposed. The sensitivity analysis of dynamic response with respect to design variables in two scales, i.e., macro and micro scales, is presented. The corresponding concurrent topology optimization of Macrostructure and microstructure is established, where the objective function is to minimize the displacement response mean square (RMS) of the prescribed degree of freedom while volume constraints are applied to the macromaterial distribution and phase materials. The optimization problem is solved using a bi-directional evolutionary structural optimization (BESO) method. Several examples are presented to demonstrate the effectiveness of the proposed method.
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Topology optimization of microstructures of cellular materials and composites for Macrostructures
Computational Materials Science, 2013Co-Authors: Xiaodong Huang, Shiwei Zhou, Yi Min XieAbstract:This paper introduces a topology optimization algorithm for the optimal design of cellular materials and composites with periodic microstructures so that the resulting Macrostructure has the maximum stiffness (or minimum mean compliance). The effective properties of the heterogeneous material are obtained through the homogenization theory, and these properties are integrated into the analysis of the Macrostructure. The sensitivity analysis for the material unit cell is established for such a two-scale optimization problem. Then, a bi-directional evolutionary structural optimization (BESO) approach is developed to achieve a clear and optimized topology for the material microstructure. Several numerical examples are presented to validate the proposed optimization algorithm and a variety of anisotropic microstructures of cellular materials and composites are obtained. The various effects on the topological design of the material microstructure are discussed.
Jicai Feng - One of the best experts on this subject based on the ideXlab platform.
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effect of ultrasonic vibration on microstructural evolution and mechanical properties of underwater wet welding joint
Journal of Materials Processing Technology, 2017Co-Authors: Jianfeng Wang, Laijun Wu, Junbo Teng, Jicai FengAbstract:Abstract The propagation of high-intensity ultrasonic vibration into weld pool can influence on microstructure and mechanical properties of welded joints. This research introduced a hybrid method for improving weld quality by using superimposed ultrasonic vibration on workpiece directly in underwater flux cored arc welding (FCAW). With the purpose of revealing how Macrostructure, microstructure and mechanical properties of welded joints are affected by ultrasonic vibration within the weld metal, the present study has been carried out. The results indicated that proeutectoid ferrite, ferrite side plate and acicular ferrite constitute the microstructures of weld metal. Ultrasonic vibration can affect the size and morphology of prior austenite grain during weld pool solidification and eventually accelerate the formation of fine ferrite microstructure of weld metal in high proportion in the subsequently solid-state phase transformation. Excellent balance of high tensile strength and impact toughness is realized as more fine columnar microstructures in weld metal with using ultrasonic vibration. These findings suggest that the addition of ultrasonic vibration is an effective way to improve the tensile strength and impact toughness of weld metal during underwater wet welding.
Maribel L. Saucedo Muñoz - One of the best experts on this subject based on the ideXlab platform.
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Influence of the chemical composition of flux on the microstructure and tensile properties of submerged-arc welds
Journal of Materials Processing Technology, 2005Co-Authors: Ana Ma. Paniagua-mercado, Victor M. Lopez-hirata, Maribel L. Saucedo MuñozAbstract:Abstract A study was conducted on the effect of flux composition for the microstructure and tensile properties of a submerged-arc welded AISI 1025 steel. Three flux compositions were used with a low-carbon electrode. A commercial flux composition was used for comparison. The welding conditions were kept the same. Tension tests were pursued at room temperature. Microstructure and Macrostructure of welds were observed with light and scanning electron microscopes (SEM). The presence of acicular ferrite was detected for welds of fluxes with the highest content of titanium oxide. The yield and ultimate tensile strengths seem to be influenced by the presence of acicular ferrite. The elongation and area reduction percentages are affected by the inclusion volume percentage. Tensile properties and microstructure were compared with the values predicted by the computer programs.
Johanna Schwarz - One of the best experts on this subject based on the ideXlab platform.
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age affects sleep microstructure more than sleep Macrostructure
Journal of Sleep Research, 2017Co-Authors: Johanna Schwarz, Torbjorn Akerstedt, Eva Lindberg, Georg Gruber, Hakan Fischer, Jenny TheorellhaglowAbstract:Summary It is well known that the quantity and quality of physiological sleep changes across age. However, so far the effect of age on sleep microstructure has been mostly addressed in small samples. The current study examines the effect of age on several measures of sleep macro- and microstructure in 211 women (22–71 years old) of the ‘Sleep and Health in Women’ study for whom ambulatory polysomnography was registered. Older age was associated with significantly lower fast spindle (effect size f2 = 0.32) and K-complex density (f2 = 0.19) during N2 sleep, as well as slow-wave activity (log) in N3 sleep (f2 = 0.21). Moreover, total sleep time (f2 = 0.10), N3 sleep (min) (f2 = 0.10), rapid eye movement sleep (min) (f2 = 0.11) and sigma (log) (f2 = 0.05) and slow-wave activity (log) during non-rapid eye movement sleep (f2 = 0.09) were reduced, and N1 sleep (f2 = 0.03) was increased in older age. No significant effects of age were observed on slow spindle density, rapid eye movement density and beta power (log) during non-rapid eye movement sleep. In conclusion, effect sizes indicate that traditional sleep stage scoring may underestimate age-related changes in sleep.
