• Title, Summary, Keyword: Stacking Sequence

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The Stacking Sequence Optimization of Stiffened Laminated Curved Panels with Different Loading and Stiffener Spacing

  • Kim Cheol;Yoon In-Se
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1541-1547
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    • 2006
  • An efficient procedure to obtain the optimal stacking sequence and the minimum weight of stiffened laminated composite curved panels under several loading conditions and stiffener layouts has been developed based on the finite element method and the genetic algorithm that is powerful for the problem with integer variables. Often, designing composite laminates ends up with a stacking sequence optimization that may be formulated as an integer programming problem. This procedure is applied for a problem to find the stacking sequence having a maximum critical buckling load factor and the minimum weight. The object function in this case is the weight of a stiffened laminated composite shell. Three different types of stiffener layouts with different loading conditions are investigated to see how these parameters influence on the stacking sequence optimization of the panel and the stiffeners. It is noticed from the results that the optimal stacking sequence and lay-up angles vary depending on the types. of loading and stiffener spacing.

Optimization of stacking sequence for composite golf club shafts (복합재료 골프샤프트의 적층최적화)

  • Kim, Moo-Sun;Han, Dong-Chul;Kim, Seon-Jin;Lee, Woo-Il
    • Composites Research
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    • v.20 no.1
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    • pp.1-7
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    • 2007
  • This study presents a methodology for optimization of static characteristics of golf club shafts. Stacking sequence for the optimal composite shaft performance is searched. A new objective function is defined for the simultaneous optimization of flexural and torsional stiffnesses. Classical lamination theory is used for the static analysis. As the optimization tool, genetic algorithm is applied with the stacking sequence as design. variables. With the optimal stacking sequence, dynamic characteristics of the shaft is also studied.

Stacking 방법과 층수에 따른 2 차원 화합물 반도체인 GaS 의 전자구조 변화

  • Yang, Ha-Nuel;Cha, Seon-Gyeong
    • Proceeding of EDISON Challenge
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    • pp.313-318
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    • 2016
  • 2차원 화합물 반도체인 Metal monochalcogenides (MMC)는 원자 4층으로 이루어진 tetralayer (TL)가 층상으로 쌓여진 구조이다. 서로 이웃한 tetralayer들이 쌓이는 방법에 따라 4가지의 stacking sequence를(${\beta}$, ${\varepsilon}$, ${\gamma}$, ${\delta}$) 고려할 수 있으며 물질에 따라 상대적인 안정성이 달라진다. GaS는 ${\beta}-type$이 가장 안정하다고 알려져 있다. 이 연구에서는 GaS의 층수를 4층까지 쌓으며, ${\beta}$${\varepsilon}$의 stacking sequence의 모든 경우를 다루어 van der Waals interaction을 고려한 LCAO-DFT 제일원리 계산을 수행하였다. 그 결과를 원자구조의 변화, 에너지 안정성, 전자구조의 변화로 나누어 분석하였다. TL 층이 많을수록 TL의 thickness가 감소하고 더 높은 에너지 안정성을 나타냈다. 또한 stacking sequence를 고려하였을 때 ${\varepsilon}$ stacking을 한 결과가 더 안정한 에너지가 나왔다. 이후 ${\varepsilon}$ stacking을 하였을때의 전자구조 변화를 energy band와 projected density of states를 이용해 관찰하였다.

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The Influence of Stacking Sequences of Carbon Fiber/Glass Fiber/PEEK Hybrid Composites on the Mechanical Properties (적층순서가 탄소섬유/유리섬유/PEEK 하이브리드 복합재료의 기계적 성질에 미치는 영향)

  • 나성기;박종신
    • Textile Science and Engineering
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    • v.40 no.3
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    • pp.232-237
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    • 2003
  • The mechanical properties of carbon fiber and glass fiber reinforced PEEK hybrid composites with different starting sequence were evaluated through tensile, flexural, interlaminar shear strength (ILSS) and impact test. Tensile and flexural strength of hybrid composites increased with the fiber volume fraction. Interlaminar shear strength was affected by stacking sequence of the hybridization. In the impact test, the hybrid composites with glass fiber ply at impact side absorbed more energy and showed synergy effect in impact energy absorption.

Layup Optimization for Composite Laminates with Discrete Ply Angles (이산 섬유 배열각을 이용한 복합재료 적층 평판의 최적 설계)

  • Kim, Tae-Uk
    • Proceedings of the KSME Conference
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    • pp.734-739
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    • 2001
  • In this paper, an algorithm for stacking sequence optimization which deals with discrete ply angles is used for optimization of composite laminated plates. To handle discrete ply angles, the branch and bound method is modified. Numerical results show that the optimal stacking sequence is found with fewer evaluations of objective function than expected with the size of feasible region, which shows the algorithm can be effectively used for layup optimization of composite laminates..

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Stacking Sequence Optimization of Composite Laminates for Railways Using Expert System (철도분야 응용을 위한 전문가 시스템을 이용한 복합적층판의 적층순서 최적설계)

  • Kim Jung-Seok
    • Journal of the Korean Society for Railway
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    • v.8 no.5
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    • pp.411-418
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    • 2005
  • This paper expounds the development of a user-friendly expert system for the optimal stacking sequence design of composite laminates subjected to the various rules constraints. The expert system was realized in the graphic-based design environment. Therefore, users can access and use the system easily. The optimal stacking sequence is obtained by means of integration of a genetic algorithm, finite element analysis. These systems were integrated with the rules of design heuristics under an expert system shell. The optimal stacking sequence combination for the application of interest is drawn from the discrete ply angles and design rules stored in the knowledge base of the expert system. For the integration and management of softwares, a graphic-based design environment that provides multi-tasking and graphic user interface capability is built.

Optimal Design of Skin and Stiffener of Stiffened Composite Shells Using Genetic Algorithms (유전자 기법을 이용한 복합재 보강구조물 외피 및 보강재의 적층각 최적설계)

  • Yoon, I.S.;Choi, H.S.;Kim, C.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.233-236
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    • 2002
  • An efficient method was developed in this study to obtain optimal stacking sequences, thicknesses, and minimum weights of stiffened laminated composite shells under combined loading conditions and stiffener layouts using genetic algorithms (GAs) and finite element analyses. Among many parameters in designing composite laminates determining a optimal stacking sequence that may be formulated as an integer programming problem is a primary concern. Of many optimization algorithms, GAs are powerful methodology for the problem with discrete variables. In this paper the optimal stacking sequence was determined, which gives the maximum critical buckling load factor and the minimum weight as well. To solve this problem, both the finite element analysis by ABAQUS and the GA-based optimization procedure have been implemented together with an interface code. Throughout many parametric studies using this analysis tool, the influences of stiffener sizes and three different types of stiffener layouts on the stacking sequence changes were throughly investigated subjected to various combined loading conditions.

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Optimal stacking sequence design of laminate composite structures using tabu embedded simulated annealing

  • Rama Mohan Rao, A.;Arvind, N.
    • Structural Engineering and Mechanics
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    • v.25 no.2
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    • pp.239-268
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    • 2007
  • This paper deals with optimal stacking sequence design of laminate composite structures. The stacking sequence optimisation of laminate composites is formulated as a combinatorial problem and is solved using Simulated Annealing (SA), an algorithm devised based on inspiration of physical process of annealing of solids. The combinatorial constraints are handled using a correction strategy. The SA algorithm is strengthened by embedding Tabu search in order to prevent recycling of recently visited solutions and the resulting algorithm is referred to as tabu embedded simulated Annealing (TSA) algorithm. Computational performance of the proposed TSA algorithm is enhanced through cache-fetch implementation. Numerical experiments have been conducted by considering rectangular composite panels and composite cylindrical shell with different ply numbers and orientations. Numerical studies indicate that the TSA algorithm is quite effective in providing practical designs for lay-up sequence optimisation of laminate composites. The effect of various neighbourhood search algorithms on the convergence characteristics of TSA algorithm is investigated. The sensitiveness of the proposed optimisation algorithm for various parameter settings in simulated annealing is explored through parametric studies. Later, the TSA algorithm is employed for multi-criteria optimisation of hybrid composite cylinders for simultaneously optimising cost as well as weight with constraint on buckling load. The two objectives are initially considered individually and later collectively to solve as a multi-criteria optimisation problem. Finally, the computational efficiency of the TSA based stacking sequence optimisation algorithm has been compared with the genetic algorithm and found to be superior in performance.

Optimal Design of Composite Laminated Plates with the Discreteness in Ply Angles and Uncertainty in Material Properties Considered (섬유 배열각의 이산성과 물성치의 불확실성을 고려한 복합재료 적층 평판의 최적 설계)

  • Kim, Tae-Uk;Sin, Hyo-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.3
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    • pp.369-380
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    • 2001
  • Although extensive efforts have been devoted to the optimal design of composite laminated plates in recent years, some practical issues still need further research. Two of them are: the handling of the ply angle as either continuous or discrete; and that of the uncertainties in material properties, which were treated as continuous and ignored respectively in most researches in the past. In this paper, an algorithm for stacking sequence optimization which deals with discrete ply angles and that for thickness optimization which considers uncertainties in material properties are used for a two step optimization of composite laminated plates. In the stacking sequence optimization, the branch and bound method is modified to handle discrete variables; and in the thickness optimization, the convex modeling is used in calculating the failure criterion, given as constraint, to consider the uncertain material properties. Numerical results show that the optimal stacking sequence is found with fewer evaluations of objective function than expected with the size of feasible region taken into consideration; and the optimal thickness increases when the uncertainties of elastic moduli considered, which shows such uncertainties should not be ignored for safe and reliable designs.

Analysis of Delamination Behavior on the Stacking Sequence of Prosthetic Foot Keel in Glass fiber Reinforced Laminates (인공발(Prosthetic Foot) 스프링용 유리섬유강화 적층재의 적층배향에 따른 층간분리거동 해석)

  • Song, Sam-Hong;Kim, Cheol-Woong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.4
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    • pp.623-631
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    • 2003
  • It is considered that the application of advanced composite materials to the prostheses for the disables is important to improve their bio-mechanical performance. Particularly, energy storing foot prosthesis is mostly important to restore gait ability of the disables with low-extremity amputation since it could provide propulsion at terminal stance enhancing the disables ability to walk long distance even run and jump. Therefore, the energy storing spring of Prosthetic foot keel under cyclic bending moment use mainly of high strength glass fiber reinforced plastic. The main objective of this study was to evaluate the stacking sequence effect using the delamination growth rate(dA$_{D}$/dN) of energy storing spring in glass fiber reinforced plastic under cyclic bending moment. The test results indicated that the shape of delamination zone depends on stacking sequence in GFRP laminates. Delamination area(A$_{D}$) turns out that variable types with the contour increased non-linearly toward the damage zones.nes.