• Title, Summary, Keyword: Multiple Material

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Development of a Material Mixing Method for Topology Optimization of Multiple Material Structures (다중재료 구조물의 위상 최적화를 위한 재료혼합법의 개발)

  • Han, Seog-Young;Lee, Soo-Kyoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.6
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    • pp.726-731
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    • 2004
  • This paper suggests a material mixing method to mix several materials in a structure. This method is based on ESO(Evolutionary Structural Optimization), which has been used to optimize topology of only one material structure. In this study, two criterions for material transformation and element removal are implemented for mixing several materials in a structure. Optimal topology for a multiple material structure can be obtained through repetitive application of the two criterions at each iteration. Two practical design examples of a short cantilever are presented to illustrate validity of the suggested material mixing method. It is found that the suggested method works very well and a multiple material structure has more stiffness than one material structure has under the same mass.

Optimization of Multiple Tower Cranes and Material Stockyards Layout (다중 양중장비와 자재 야적 위치의 최적 결정을 위한 모델 개발)

  • Kim, Kyong-Ju;Kim, Kyoung-Min;Lee, Sang-Kyu
    • Korean Journal of Construction Engineering and Management
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    • v.10 no.6
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    • pp.127-134
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    • 2009
  • This study aims to provide an optimal model for the layout of multiple tower cranes and material stockyards which have multiple candidate positions. In a high-rise building construction, the positional allocation of tower cranes and material stockyard has an effect on the travel time of material hauling. In addition, in case of using multiple tower cranes, specific location of a tower crane allocated to each material determines the efficiency of the works. Current optimal model limited to the optimization of position of single tower crane and material stockyards. This study suggests optimal model both for the positions of multiple tower cranes and material stockyards. Layout of multiple tower cranes requires additional allocation of each crane to each material hauling and control on the minimum distance between tower cranes. This optimization model utilizes genetic algorithm to deal with complex interaction on the candidate positions of multiple tower cranes, material stockyards, and types of materials. In order to identify its utility, case study was performed.

Development of a Material Mixing Method using ESO (진화적 구조 최적화를 이용한 재료 혼합법의 개발)

  • 한석영;이수경;신민석
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.259-264
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    • 2003
  • This paper suggests a material mixing method to mix several materials in a structure. This method is based on ESO(Evolutionary Structural Optimization), which has been used to optimize topology of only one material structure. In this study, two criterions for material transformation and element removal are implemented for mixing several materials in a structure. Optimal topology for a multiple material structure can be obtained through repetitive application of the two criterions at each iteration. Two practical design examples of a short cantilever are presented to illustrate validity of the suggested material mixing method. It is found that the suggested method works very well and a multiple material structure has more stiffness than one material structure has under the same mass.

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Multi-Crack Problems for Non-homogeneous Material Subjected to Unsteady Thermal Load (비정상 열 하중을 받는 이질재료의 다중 크랙 문제)

  • Kim, Kui-Seob
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.19 no.1
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    • pp.15-23
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    • 2011
  • The purpose of this paper is to investigate the time behavior of a multiple crack problems. It is assumed that the medium contains cracks perpendicular to the crack surfaces, that the thermo-mechanical properties are continuous functions of the thickness coordinate. we use the laminated composite plate model to simulate the material non-homogeneity. By utilizing the Laplace transform and Fourier transform techniques, the multiple crack problems in the non-homogeneous medium is formulated. Singular integral equations are derived and solved to investigate the multiple crack problems. As a numerical illustration, transient thermal stress intensity factors(TSIFs) for a functionally graded material plate subjected to sudden heating on its boundary are provided. The variation in the TSIFs due to the change in material gradient and the crack position is studied.

Development of a Multi-material Stereolithography System (다중재료 광조형장치 개발)

  • Kim, Ho-Chan;Choi, Jae-Won;Wicker, Ryan
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.3
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    • pp.135-141
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    • 2010
  • Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats positioned on a rotating vat carousel that contain different photo-curable materials. To change the material during the process, the build platform is raised out of the current vat, a new vat with a different material is rotated under the platform, and the platform is submerged into the new vat so that the new material can be used. This paper introduces a new vat exchange mechanism, cleaning process, recoating process, resin leveling mechanism and process planning technologies for the implementation of multiple material SL. An overview of the system framework is provided and the system integration and control software is described. In addition, several multiple material test parts are designed, fabricated, and described.

Numerical analysis of heat transfer for architectural structure composed of multiple materials in ISO10211 (복합재질로 구성된 건축 구조체의 열전달 수치해석을 위한 ISI10211모델계산)

  • Lee, Juhee;Park, JiHo;Lee, YongJun
    • KIEAE Journal
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    • v.16 no.6
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    • pp.159-166
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    • 2016
  • Purpose: The architectural structures in the engineering field include more than one material, and the heat transfer through these multiple materials becomes complicated. More or less, the analytic solutions obtained by the hand calculation can provide the limited information of heat transfer phenomena. However, the engineers have generally been forced to obtain reliable results than those of the hand calculation. The numerical calculation such as a finite volume methods with the unstructured grid system is only the suitable means of the analysis for the complex and arbitrary domains that consists of multiple materials. In this study, a new numerical code is developed to provide temperature distributions in the multiple material domains, and the results of this code are compared with the validation cases in ISO10211. Method: Finite volume methods with an unstructured grid is employed. In terms of numerical methods, the heat transfer conduction coefficient is not defined on the surface of the cell between different material cells. The heat transfer coefficient is properly defined to accurately mimic the heat transfer through the surface. The boundary conditions of heat flux considering radiation or heat convection are also developed. Result: The comparison between numerical results and ISO 10211 cases. We are confirmed that the numerical method provides the proper temperature distributions, and the heat transfer equation and its boundary conditions are developed properly.

Simultaneous Optimization of Multiple Quality Characteristics in Laser Beam Cutting Using Taguchi Method

  • Dubey, Avanish Kumar;Yadava, Vinod
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.4
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    • pp.10-15
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    • 2007
  • Taguchi methods have been used for a long time to improve the product quality and process performance of a manufacturing system, Few researchers have applied this methodology in laser beam cutting (LBC) of sheet metals and found the considerable improvement in cut qualities. In all experimental investigations of LBC so far, the objective was to optimize the single quality characteristic at a time. In this paper the simultaneous optimization of multiple quality characteristics such as Kerf width and material removal rate (MRR) during pulsed Nd:YAG LBC of thin sheet of magnetic material (high Silicon-steel) has been presented using Taguchi's quality loss function. The results show the considerable improvement in multiple S/N ratio as compared to initial cutting condition. Also, the comparison of results from single and multi-objective optimization have been presented and it was found that the loss in quality is always possible shifting from single quality to multiple quality optimization.

Broad-band Multi-layered Radar Absorbing Material Design for Radar Cross Section Reduction of Complex Targets Consisting of Multiple Reflection Structures (다중반사 구조를 갖는 복합구조물의 RCS 감소를 위한 광대역 다층 전파흡수체 설계)

  • Kim, Kook-Hyun;Cho, Dae-Seung;Kim, Jin-Hyeong
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.4
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    • pp.445-450
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    • 2007
  • An optimum design process of the broad-band multi-layered radar absorbing material, using genetic algorithm, is established for the radar cross section reduction of a complex target, which consists of multiple reflection structures, such as surface warships. It follows the successive process of radar cross section analysis, scattering center analysis, radar absorbing material design, and reanalysis of radar cross section after applying the radar absorbing material. It is demonstrated that it is very effective even in the optimum design of the multi-layer radar absorbing material. This results from the fact that the three factors, i.e.. the incident angle range, broad-band frequencies, and maximum thickness can be simultaneously taken into account by adopting the genetic algorithm.

Multi-material topology optimization of Reissner-Mindlin plates using MITC4

  • Banh, Thien Thanh;Lee, Dongkyu
    • Steel and Composite Structures
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    • v.27 no.1
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    • pp.27-33
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    • 2018
  • In this study, a mixed-interpolated tensorial component 4 nodes method (MITC4) is treated as a numerical analysis model for topology optimization using multiple materials assigned within Reissner-Mindlin plates. Multi-material optimal topology and shape are produced as alternative plate retrofit designs to provide reasonable material assignments based on stress distributions. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. Mathematical formulation of multi-material topology optimization problem solving minimum compliance is an alternating active-phase algorithm with the Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples illustrate the reliability and accuracy of the present design method for multi-material topology optimization with Reissner-Mindlin plates using MITC4 elements and steel materials.