• 제목/요약/키워드: Material Properties Optimization

검색결과 357건 처리시간 0.03초

장애함수법에 의한 신뢰성기반 최적설계 (Barrier Function Method in Reliability Based Design Optimization)

  • 이태희;최운용;김홍선
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1130-1135
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    • 2003
  • The need to increase the reliability of a structural system has been significantly brought in the procedure of real designs to consider, for instance, the material properties or geometric dimensions that reveal a random or incompletely known nature. Reliability based design optimization of a real system now becomes an emerging technique to achieve reliability, robustness and safety of these problems. Finite element analysis program and the reliability analysis program are necessary to evaluate the responses and the probabilities of failure of the system, respectively. Moreover, integration of these programs is required during the procedure of reliability based design optimization. It is well known that reliability based design optimization can often have so many local minima that it cannot converge to the specified probability of failure. To overcome this problem, barrier function method in reliability based design optimization is suggested. To illustrate the proposed formulation, reliability based design optimization of a bracket is performed. AMV and FORM are employed for reliability analysis and their optimization results are compared based on the accuracy and efficiency.

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강도 및 강성 조건을 고려한 탄소섬유강화플라스틱(CFRP) 로어 컨트롤 아암의 치수 최적설계 (Sizing Optimization of CFRP Lower Control Arm Considering Strength and Stiffness Conditions)

  • 임주희;도재혁;유상혁;강오성;강건욱;이종수
    • 한국CDE학회논문집
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    • 제21권4호
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    • pp.389-396
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    • 2016
  • The necessity for environment-friendly material development has emerged in the recent automotive field due to stricter regulations on fuel economy and environmental concerns. Accordingly, the automotive industry is paying attention to carbon fiber reinforced plastic (CFRP) material with high strength and stiffness properties while the lightweight. In this study, we determine a shape of lower control arm (LCA) for maximizing the strength and stiffness by optimizing the thickness of each layer when the stacking angle is fixed due to the CFRP manufacturing problems. Composite materials are laminated in the order of $0^{\circ}$, $90^{\circ}$, $45^{\circ}$, and $-45^{\circ}$ with a symmetrical structure. For the approximate optimal design, we apply a sequential two-point diagonal quadratic approximate optimization (STDQAO) and use a process integrated design optimization (PIDO) code for this purpose. Based on the physical properties calculated within a predetermined range of laminate thickness, we perform the FEM analysis and verify whether it satisfies the load and stiffness conditions or not. These processes are repeated for successive improved objective function. Optimized CFRP LCA has the equivalent stiffness and strength with light weight structure when compared to conventional aluminum design.

리플로 납땜과정에서 플라스틱 IC 패키지의 박리방지를 위한 응력최적설계의 적용 (Application of Stress Optimization for Preventing the Delamination of the Plastic IC Package in Reflow Soldering Process)

  • 김근우;이강용;김옥환
    • 대한기계학회논문집A
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    • 제28권6호
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    • pp.709-716
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    • 2004
  • In order to prevent the interface delamination of an plastic IC package in the infrared (IR) soldering process, we tried to reduce stress by parameterization, sensitivity analysis and unconstraint optimization. The design variables of dimensions and material properties are determined among all the possible variables from the parametric study. Their optimized values are determined by applying the unconstraint optimization to the parameterized IC package. The maximum von-Mises stress value decreases greatly by optimum design.

열탄성 구조물의 최적설계 (Design Optimization of Thermo-Elastic Structure)

  • 조희근;박영원
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2000년도 추계학술대회 논문집
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    • pp.381-384
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    • 2000
  • Multi-disciplinary optimization design concept can provide a solution to many engineering problems. In the field of structural analysis, much development of size or topology optimization has been achieved in the application of research. This paper demonstrates an optimum design of a multi-layer cylindrical tube which behaves thermoelastically. A multi-layer cylindrical tube that has several different material properties at each layer is optimized within allowable stress and temperature range when mechanical and thermal loads are applied simultaneously. To analyze these problems using an efficient and precise method, the optimization theories are adopted to perform thermoelastic finite element analysis.

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Optimal Shape Design of Dielectric Micro Lens Using FDTD and Topology Optimization

  • Chung, Young-Seek;Lee, Byung-Je;Kim, Sung-Chul
    • Journal of the Optical Society of Korea
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    • 제13권2호
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    • pp.286-293
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    • 2009
  • In this paper, we present an optimal shape design method for a dielectric microlens which is used to focus an incoming infrared plane wave in wideband, by exploiting the finite difference time domain (FDTD) technique and the topology optimization technique. Topology optimization is a scheme to search an optimal shape by adjusting the material properties, which are design variables, within the design space. And by introducing the adjoint variable method, we can effectively calculate a derivative of the objective function with respect to the design variable. To verify the proposed method, a shape design problem of a dielectric microlens is tested when illuminated by a transverse electric (TE)-polarized infrared plane wave. In this problem, the design variable is the dielectric constant within the design space of a dielectric microlens. The design objective is to maximally focus the incoming magnetic field at a specific point in wideband.

배관용 관 이음쇠 내외경 동시 교정툴의 신뢰성 평가 (Study of Structural Reliability of Pipe-Fitting Collet Tool)

  • 김창욱;박진철;송정일
    • 한국기계가공학회지
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    • 제14권4호
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    • pp.140-145
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    • 2015
  • In the present study, the structural safety of the bolt portion and collet tool structure of the pipe-fitting tool is analyzed by using the finite element technique. Two forces as piston forces with the magnitude of 187.5 Tons are applied to the inner and outer portions of the collet tool, respectively. A structural load of 750 Tons is applied to the bolt portion. In the analysis results, it is found that the structure becomes safe under the current loading conditions. The reliability rating of the pipe is calculated in this study. The material properties of the actual material are evaluated by using mechanical testing. Therefore, the material properties are used to carry out static structural and optimization analysis.

선택적 단결정 실리콘 성장의 반도체 소자 적용 (SEG Applications for Semiconductor Devices)

  • 정우석
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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    • pp.9-10
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    • 2005
  • Process diagrams of selective epitaxial growth of silicon(SEG) could be developed from CVD thermodynamics. They could not only be helpful with understanding of the mechanism, but also offer good processing guidelines in manufacturing high density devices. Through the process optimization skill, applications of SEG to high-density device structures could be possible without problems such as loading effect and facet generation, with producing outstanding electronic properties.

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비선형 최적화 기법을 이용한 압전 세라믹의 복소 재료 정수 규명 (An Identification Method for Complex-Valued Material Properties of Piezoelectric Ceramics Using Nonlinear Optimization Technique)

  • 조치영;서희선;김대환
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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    • pp.298-305
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    • 1996
  • The common practice for the identification of piezoelectric properties is based on the use of immittance behavior of a resonator with a certain geometry and poling direction. In this paper, a new method is suggested to identify the complex-valued piezoelectric material constants. This method is based on the minimization of differences between the analytical immittance and the experimental measurement of resonator. Non-linear minimization problems are formulated to find out the unknown properties relevant to the resonators. The immittance data used for identification are measured at a number of frequencies which cover the vicinity of resonance frequency and the low frequency region. To illustrate the proposed technique, the complex-valued coefficients are identified for a typical PZT4 ceramic composition.

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고분자 분상형 액정표시소자의 전기광학적 특성 연구 (Electro-optical Properties of Polymer Dispersed Liquid Crysta Displays)

  • 박우상;고영부;박세근
    • 한국전기전자재료학회논문지
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    • 제11권10호
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    • pp.885-890
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    • 1998
  • The electro-optical properties of polymer dispersed liquid crystals (PDLCs) depend on dispersion structures and nematic alignment which can be controlled by taking proper liquid crystal/polymer mixtures and process conditions. To achieve excellent electro-optical properties such as low driving voltage, good contrast ratio and negligible hysteresis, we have developed optimization procedure. Under the optimized conditions, PDLC of low threshold voltage less than 3.1 V, high contrast ratio more than 150 and negligible hysteresis were obtained.

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Inter-Pillar 진동 모드를 고려한 1-3형 압전복합체의 구조 최적화 (Optimization of 1-3 Type Piezocomposite Structures Considering Inter-Pillar Vibration Modes)

  • 표성훈;김진욱;노용래
    • 한국전기전자재료학회논문지
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    • 제26권6호
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    • pp.434-440
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    • 2013
  • With polymer properties and ceramic volume fraction as design variables, the optimal structure of 1-3 piezocomposites has been determined to maximize the thickness mode electromechanical coupling factor. When the piezocomposite vibrates in a thickness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorates the performance of the piezocomposite. In this work, a new method to design the structure of the 1-3 type piezocomposite is proposed to maximize the thickness mode electromechanical coupling factor while preventing the occurrence of the inter-pillar modes. Genetic algorithm was used for the optimal design, and the finite element analysis method was used for the analysis of the inter-pillar mode.