• Title, Summary, Keyword: Shape optimization

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Structural Shape Optimization under Static Loads Transformed from Dynamic Loads (동하중으로부터 변환된 등가정하중을 통한 구조물의 형상최적설계)

  • Park, Ki-Jong;Lee, Jong-Nam;Park, Gyung-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.8
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    • pp.1363-1370
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    • 2003
  • In structural optimization, static loads are generally utilized although real external forces are dynamic. Dynamic loads have been considered in only small-scale problems. Recently, an algorithm for dynamic response optimization using transformation of dynamic loads into equivalent static loads has been proposed. The transformation is conducted to match the displacement fields from dynamic and static analyses. The algorithm can be applied to large-scale problems. However, the application has been limited to size optimization. The present study applies the algorithm to shape optimization. Because the number of degrees of freedom of finite element models is usually very large in shape optimization, it is difficult to conduct dynamic response optimization with the conventional methods that directly threat dynamic response in the time domain. The optimization process is carried out via interfacing an optimization system and an analysis system for structural dynamics. Various examples are solved to verify the algorithm. The results are compared to the results from static loads. It is found that the algorithm using static loads transformed from dynamic loads based on displacement is valid even for very large-scale problems such as shape optimization.

Shape Optimization of Cutouts in a Laminated Composite Plate Using Volume Control (체적제어에 의한 적층 복합재 구멍의 형상 최적화)

  • Han, Seog-Young;Ma, Young-Joon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.9
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    • pp.1337-1343
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    • 2004
  • Shape optimization was performed to obtain a precise shape of cutouts including the internal shape of cutouts in a laminated composite plate by three dimensional modeling using solid element. Volume control of the growth-strain method was implemented and the distributed parameter chosen as Tsai-Hill fracture index for shape optimization. It makes Tsai-Hill failure index at each element uniform in laminated composites under the predetermined volume a designer requires. Shapes optimized by Tsai-Hill failure index were compared with those of the initial shapes for the various load conditions and cutouts. The following conclusions were obtained in this study; (1) It was found that growth-strain method was applied efficiently to shape optimization of three dimensional cutouts in a laminate composite, (2) The optimal shapes of the various load conditions and cutouts were obtained, (3) The maximum Tsai-Hill failure indices of the optimal shapes were remarkably reduced comparing with those of the initial shapes.

Shape and Thickness Optimization of an Aluminium Duo-type LPG Tank for a Passenger Car (승용차용 알루미늄 듀오타입 LPG 탱크의 형상 및 두께 최적설계)

  • So, Soon-Jae;Choi, Gyoo-Jae;Jang, Gang-Won
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.2
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    • pp.131-135
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    • 2013
  • In this study, to develop a light weight duo type aluminum LPG tank in stead of a conventional steel tank optimization technology is used. Two types of optimization method are carried out for internal compression test simulation of a LPG tank. The first is the thickness only optimization of LPG tank components. The second is the thickness and shape optimization. For the case of the thickness only optimization the weight reduction rate of an optimized tank compare to that of the initial design is 42%. Also 48% weight reduction was achieved for the case of the thickness and shape optimization.

Shape Optimization of Metal Forming and Forging Products using the Stress Equivalent Static Loads Calculated from a Virtual Model (가상모델로부터 산출된 응력 등가정하중을 이용한 금속 성형품 및 단조품의 형상최적설계)

  • Jang, Hwan-Hak;Jeong, Seong-Beom;Park, Gyung-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.11
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    • pp.1361-1370
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    • 2012
  • A shape optimization is proposed to obtain the desired final shape of forming and forging products in the manufacturing process. The final shape of a forming product depends on the shape parameters of the initial blank shape. The final shape of a forging product depends on the shape parameters of the billet shape. Shape optimization can be used to determine the shape of the blank and billet to obtain the appropriate final forming and forging products. The equivalent static loads method for non linear static response structural optimization (ESLSO) is used to perform metal forming and forging optimization since nonlinear dynamic analysis is required. Stress equivalent static loads (stress ESLs) are newly defined using a virtual model by redefining the value of the material properties. The examples in this paper show that optimization using the stress ESLs is quite useful and the final shapes of a forming and forging products are identical to the desired shapes.

Shape Optimization of Three-Dimensional Cutouts in Laminated Composite Plates Using Solid Element (솔리드 요소를 이용한 적층복합재 구멍의 형상 최적화)

  • 한석영;마영준
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.4
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    • pp.16-22
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    • 2004
  • Shape optimization was performed to obtain the precise shape of cutouts including the internal shape of cutouts in laminated composite plates by three dimensional modeling using solid element. The volume control of the growth-strain method was implemented and the distributed parameter chosen as Tsai-Hill fracture index for shape optimization. The volume control of the growth-strain method makes Tsai-Hill failure index at each element uniform in laminated composites under the initial volume. Then shapes optimized by Tsai-Hill failure index were compared with those of the initial shapes for the various load conditions and cutouts. The following conclusions were obtained in this study (1) It was found that growth-strain method was applied efficiently to shape optimization of three dimensional cutouts in a laminated composite plate, (2) The optimal shapes on the various load conditions and cutouts were obtained, (3) The maximum Tsai-Hill failure index was reduced up to 67% when shape optimization was performed under the initial volume by volume control of growth-strain method.

Shape optimization of blended-wing-body underwater glider by using gliding range as the optimization target

  • Sun, Chunya;Song, Baowei;Wang, Peng;Wang, Xinjing
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.9 no.6
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    • pp.693-704
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    • 2017
  • Blended-Wing-Body Underwater Glider (BWBUG), which has excellent hydrodynamic performance, is a new kind of underwater glider in recent years. In the shape optimization of BWBUG, the lift to drag ratio is often used as the optimization target. However this results in lose of internal space. In this paper, the energy reserve is defined as the direct proportional function of the internal space of BWBUG. A motion model, which relates gliding range to steady gliding motion parameters as well as energy consumption, is established by analyzing the steady-state gliding motion. The maximum gliding range is used as the optimization target instead of the lift to drag ratio to optimizing the shape of BWBUG. The result of optimization shows that the maximum gliding range of initial design is increased by 32.1% though an Efficient Global Optimization (EGO) process.

Parallel 3-D Aerodynamic Shape Optimization on Unstructured Meshes

  • Lee, Sang-Wook;Kwon, Oh-Joon
    • International Journal of Aeronautical and Space Sciences
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    • v.4 no.1
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    • pp.45-52
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    • 2003
  • A three-dimensional aerodynamic shape optimization technique in inviscid compressible flows is developed by using a parallel continuous adjoint formulation on unstructured meshes. A new surface mesh modification method is proposed to overcome difficulties related to patch-level remeshing for unstructured meshes, and the effect of design sections on aerodynamic shape optimization is examined. Applications are made to three-dimensional wave drag minimization problems including an ONERA M6 wing and the EGLIN wing-pylon-store configuration. The results show that the present method is robust and highly efficient for the shape optimization of aerodynamic configurations, independent of the number of design variables used.

Shape Optimization of the H-shape Spacer Grid Spring Structure

  • Yoon, Kyung-Ho;Kim, Hyung-Kyu;Kang, Heung-Seok;Song, Kee-Nam;Park, Ki-Jong
    • Nuclear Engineering and Technology
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    • v.33 no.5
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    • pp.547-555
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    • 2001
  • In pressurized light water reactor fuel assembly, spacer grids support nuclear fuel rods both laterally and vertically. The fuel rods are supported by spacer grid springs and grid dimples that are located in the grid cell. The support system allows for some thermal expansion and imbalance of the fuel rods. The imbalance is absorbed by elastic energy to prevent coolant flow- induced vibration damage. Design requirements are defined and a design process is established. The design process includes mathematical optimization as well as practical design method. The shape of the grid spring is designed to maintain its function during the lifetime of the fuel assembly. A structural optimization method is employed for the shape design. Since the optimization is carried out in the linear range of finite element analysis, the optimum solution is verified by nonlinear analysis. A good design is found and the final design is compared with the initial conceptual design. Commercial codes are utilized for structural analysis and optimization.

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Shape Optimization of A Micromixer with Herringbone Grooves Using Kriging Model (헤링본 미세혼합기의 크리깅 모델을 사용한 최적형상설계)

  • Ansari, Mubashshir Ahmad;Kim, Kwang-Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.8
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    • pp.711-717
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    • 2007
  • Shape optimization of a staggered herringbone groove micromixer using three-dimensional Navier-Stokes analysis has been carried using Kriging model. The analysis of the degree of mixing is performed by the calculation of spatial data statistics. The calculation of the variance of the mass fraction at various nodes on a plane in the channel is used to quantify mixing. A numerical optimization technique with Kriging model is applied to optimize the shape of the grooves on a single wall of the channel. Three design variables, namely, the ratio of groove width to groove pitch, the ratio of the groove depth to channel height ratio and the angle of the groove, are selected for optimization. A mixing index is used as the objective function. The results of the optimization show that the mixing is very sensitive to the shape of the groove which can be used in controlling mixing in microdevices.

Evolutionary Shape Optimization of Flexbeam Sections of a Bearingless Helicopter Rotor

  • Dhadwal, Manoj Kumar;Jung, Sung Nam;Kim, Tae Joo
    • Composites Research
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    • v.27 no.6
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    • pp.207-212
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    • 2014
  • The shape optimization of composite flexbeam sections of a bearingless helicopter rotor is studied using a finite element (FE) sectional analysis integrated with an efficient evolutionary optimization algorithm called particle swarm assisted genetic algorithm (PSGA). The sectional optimization framework is developed by automating the processes for geometry and mesh generation, and the sectional analysis to compute the elastic and inertial properties. Several section shapes are explored, modeled using quadratic B-splines with control points as design variables, through a multiobjective design optimization aiming minimum torsional stiffness, lag bending stiffness, and sectional mass while maximizing the critical strength ratio. The constraints are imposed on the mass, stiffnesses, and critical strength ratio corresponding to multiple design load cases. The optimal results reveal a simpler and better feasible section with double-H shape compared to the triple-H shape of the baseline where reductions of 9.46%, 67.44% and 30% each are reported in torsional stiffness, lag bending stiffness, and sectional mass, respectively, with critical strength ratio greater than 1.5.