• Title, Summary, Keyword: 설계 민감도해석

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Reliability Analysis Modeling for LRFD Design of Bridge Abutments (LRFD 설계를 위한 교대의 신뢰성 해석 모델)

  • Eom, Jun-Sik
    • Journal of the Korean Geotechnical Society
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    • v.30 no.8
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    • pp.5-11
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    • 2014
  • The objective of this paper is to develop a rational reliability analysis procedure for the LRFD design provisions of bridge substructures. A bridge abutments is considered in this study. The reliability analysis is applied to determine the relationship between the major design parameters for bridge abutment and reliability index. The considered load components include dead load, vertical and horizontal earth pressure, earth surcharge, and vehicle live load. Several limit states are considered: foundation bearing capacity, sliding, and overturning. The analysis results show that the most important parameter in the reliability analysis is the effective stress friction angle of the soil. The reliability indices are calculated using Monte Carlo simulations for a selected bridge abutment. The results of the sensitivity analysis indicate that reliability index is most sensitive with regard to resistance factor and horizontal earth pressure factor.

Design Sensitivity Analysis of Elasto-perfectly-plastic Structure for Stiffened Shell Structure (탄성-완전-소성 보강쉘 구조물의 설계민감도해석)

  • Jung, Jae-Joon;Lee, Tae-Hee;Lim, Jang-Keun
    • Proceedings of the KSME Conference
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    • pp.746-752
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    • 2001
  • Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

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Development of Nonlinear Static Design Sensitivity Analysis Based ANSYS (ANSYS 비선형 정적설계민감도해석 외부모듈 개발)

  • Choi, Byung-Nam;Jung, Jae-Jun;Yoo, Jung-Hoon;Lee, Tae-Hee
    • Proceedings of the KSME Conference
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    • pp.543-547
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    • 2001
  • CAE has been settled down to an indispensable tool for the simulation of a mechanical system according to the development of computer-aided analysis rapidly. Particularly finite element programs have advanced to the one of most valuable things in the filed of CAE due to the remarkable progress in the implementation. But since this analysis tool mostly provides the result of the analysis, it cannot satisfy designers who are seeking for information to improve their designs. Therefore, design sensitivity analysis or optimization module has been incorporated into commercial FEA programs to satisfy the desire of designers since 1990s. Design sensitivity analysis is to compute the rate of change of response with respected to design variable. Design sensitivity analysis is classfied into static design sensitivity analysis, Eigenvalue design sensitivity analysis and dynamic design sensitivity analysis. In this research, it will be presented to nonlinear static design sensitivity analysis formulation and nonlinear static design sensitivity analysis external module based ANSYS have been developed and illustrated an example to verify the developed module.

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Optimal Design of the Deep-sea Unmanned Vehicle Frame Design Sensitivity (심해용 무인잠수정 구조의 민감도해석에 의한 최적설계)

  • 이재환;허유정;정태환;이종무
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.3
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    • pp.28-34
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    • 2004
  • This paper presents the results of the structural analysis and optimal design of the ROV to be operated at 6000m depth in the ocean. This will be the first domestic deep-sea ROV operating with an AUV and a launcher equipped with robot arms and the current weight is about 3 ton. initial optimal dimension of the frame is determined based on the stress analysis using FEA code ANSYS and design sensitivity and optimization results. The current design is the initial design and there is a possibility to change the design according to the modification of material, equipments and array of structure.

A Study on the Correlation between Optimal Safety of Structures and Minimization of Life Cycle Cost(LCC) (구조물의 최적안전지수와 생애주기비용의 상관관계에 관한 연구)

  • Bang, Myung-Seok
    • Journal of the Korean Society of Safety
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    • v.29 no.6
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    • pp.94-98
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    • 2014
  • This study was intend to develop the optimal design method of suspension bridge by the reliability analysis based on minimization of life cycle cost(LCC). The reliability analysis was performed considering aleatory uncertainties included in the result of numerical analysis. The optimal design was estimated based on life-cycle cost analysis depending on the result of reliability analysis. As the effect of epistemic uncertainty, the safety index (beta), failure probability (pf) and minimum life cycle cost were random variables. The high-level distributions were generated, from which the critical percentile values were obtained for a conservative bridge design through sensitivity assessment.

Direct Differentiation Method for Shape Design Sensitivity Analysis of Axisymmetric Elastic Solids by the BEM and Shape Optimization of Turbin Disc (경계요소법에 의한 축대칭 탄성체의 형상설계 민감도해석을 위한 직접미분법과 터빈 디스크의 형상최적설계)

  • Lee, Bu-Yun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.5
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    • pp.1458-1467
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    • 1996
  • A direct differentiationmethod is presented for the shape design sensitivity analysis of axisymmeetric elastic solids. Based on the exisymmetric boundary integralequaiton formulation, a new boundary ntegral equatio for sensitivity analysis is derived by taking meterial derivative to the same integral identity that was used in the adjoint variable melthod. Numerical implementation is performed to show the applicaiton of the theoretical formulation. For a simple example with analytic solution, the sensitivities by present method are compared with analytic sensitivities. As an application to the shape optimization, an optimal shape of a gas turbine disc toinimize the weight under stress constraints is found by incorporating the sensitivity analysis algorithm in an optimizatio program.

Topology Optimization of Electromagnetic Systems Using Material Sensitivity Analysis (매질 민감도해석을 이용한 전자기시스템의 위상 최적설계)

  • Byun Jin-Kyu;Choi Hong-Soon;Hahn Song-Yop;Park Il-Han
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.4
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    • pp.163-173
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    • 2005
  • The conventional optimization study for electromagnetic systems has been mostly on the shape or size optimization. The goal for these optimization methods is to improve performance of electromagnetic systems by optimizing the interface shape of two different materials while their given layout or initial topology are held. The feasible topology can be diverse and an appropriate topology will give much better design results. In this paper we propose a theory and an algorithm for topology optimization of electromagnetic systems, which are based on the finite element method. The topology optimization technique employes a direct searching method of sensitivity analysis in which the information of material sensitivity is used. Two numerical examples of a switched reluctance motor and an electrostatic actuator of MEMS are tested and their design results show that the optimization method is valid and useful for the topology and basic layout design of electromagnetic systems.

Design of a Shielded Reflection Type Pulsed Eddy Current Probe for the Evaluation of Thickness (두께 평가를 위한 차폐된 반사형 펄스 와전류 탐촉자의 설계)

  • Shin, Young-Kil;Choi, Dong-Myung
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.5
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    • pp.398-408
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    • 2007
  • For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation.

A Design of The Meander Line Inductor With Good Sensitivity Using Aperture Ground plate and Multi-layer PCB (개구 접지 면과 적층 PCB를 이용한 우수한 민감도를 갖는 미앤더 선로 인덕터 설계)

  • Kim, Yu-Seon;Nam, Hun;Jung, Jin-Woo;Lim, Yeong-Seog
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.12
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    • pp.75-82
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    • 2006
  • In this paper, we design the meander line inductors with high sensitivity and high quality factor(Q) using high characteristic impedance of aperture ground plate. Sensitivity as a frequency is new defined by variation of effective inductance per analysis frequency range instead of self resonance frequency (SRF). An equivalent lumped circuit is derived to explain the characteristic of high frequency inductor. The 4 nH meander line inductor with aperture ground plate has 0.45 nH/GHz of good sensitivity and 86 of Q at 0.7 GHz.

Design to Reduce Structure-borne Noise in Outdoor Unit of Air Conditioner Using Structural Optimization with Frequency Constraints (고유진동수 제약식을 갖는 구조 최적화를 통한 에어컨 실외기의 구조기인소음 저감 설계)

  • 최상현;박남규;박윤식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.179-184
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    • 2001
  • 대부분의 제품 생산 시에는 시제품을 제작하여 이에 대한 성능 심사를 통해 미비한 부분을 보완하기 위한 재설계 작업과정을 필요로 한다. 설계 작업에 가장 중요한 부분인 특정 설계 변수에 대한 민감도의 파악은 설계 작업의 핵심적인 역할을 하고 있다. 대개의 경우 진동설계를 위한 설계변수로 구조물의 단위면적, 길이, 재료의 성질과 같은 물리적인 변수를 많이 활용하고 있으며 이러한 변수들에 대한 민감도 해석 기법들은 이미 많은 연구를 통해 실용화되고 있다. 그러나 이러한 변수만으로는 주어진 조건을 만족하도록 설계하기가 어려운 경우가 있다. 이런 경우는 부가구조물을 첨가하여 저진동 설계조건을 만족하는 구조물을 제작하는 것이 보편적이다. 한편, 구조물의 최적화 과정에서 고유진동수를 고려해야 하는 경우가 많다. 저주파 영역의 문제에서는 첫번째 고유진동수가 구조물의 진동량에 관계되는 중요한 요인이 되고, 또한 공진에 의한 문제가 발생했을 경우에는 고유진동수를 옮겨서 공진을 회피할 수 있기 때문이다. 본 연구에서는 에어컨 실외기의 진동을 저감하고 그로 인한 구조기인 소음을 저감하기 위하여 음압 레벨을 바탕으로 정한 관심 주파수 영역에 고유진동수가 존재하지 않도록 부가구조물을 최적화하였다. 최적화에 필요한 민감도는 신뢰성 있는 유한요소 모델을 구성하는 것이 쉽지 않으므로 실험으로 구한 주파수 응답함수를 이용하였다.

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