• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.11
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• pp.963-971
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• 2012

In this paper, development of optimal design tools for wing structure is described including multi load spectra condition and fatigue analysis. Two dimensional CFD result are used for calculating aerodynamic force. Design variables are composed of a number of rib and spar, positions, and thickness of each structural member. The mission profile for fatigue analysis is composed based upon the results of CFD analysis, the flight-by-flight spectra method, the excessive curves for gust loads. Minor's rule was used to deal with multi-load condition. Stress analysis and fatigue analysis are performed to calculate objective functions. Particle Swarm Optimization(PSO) algorithm was used to apply to problems which have dozens of design variables.

• Composites Research
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• v.35 no.5
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• pp.340-346
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• 2022

In this study, an optimal structural design of composite helicopter blades is performed using the genetic algorithm-based optimizer PSGA (Particle Swarm assisted Genetic Algorithm). The blade sections consist of the skin, spar, form, and balancing weight. The sectional geometries are generated using the B-spline curves while an opensource code Gmsh is used to discretize each material domain which is then analyzed by a finite element sectional analysis program Ksec2d. The HART II blade formed based on either C- or D-spar configuration is exploited to verify the cross-sectional design framework. A numerical simulation shows that each spar model reduces the blade mass by 7.39% and 6.65%, respectively, as compared with the baseline HART II blade case, while the shear center locations being remain close (within 5% chord) to the quarter chord line for both cases. The effectiveness of the present optimal structural design framework is demonstrated, which can readily be applied for the structural design of composite helicopter blades.

• Journal of the KSME
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• v.57 no.11
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• pp.44-49
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• 2017

항공용 가스터빈엔진 개발은 전문성과 경험을 요하는 많은 요소기술과 시험설비, 그리고 상당한 개발기간과 세부단계별 검증을 필요로 하는 복잡한 프로세스로 구성된다. 고온/고압 및 고속 회전 등 매우 가혹한 조건에서 운용되는 제품 특성 때문에 장납기 및 고가의 내열/고강도 소재 혹은 주단조 개발, 정밀한 제작 치수 및 공정관리, 코팅/브레이징/용접 등 고 난이도의 특수공정관리, 정교한 조립 및 다양한 종류의 엔진 검증 시험 등을 필요로 하며 이러한 이유로 상세설계 이후의 조립/시험 단계에서 설계변경이 발생할 경우 개발일정 및 비용 관점에서 제품개발에 큰 부담을 초래하게 된다. 공력/이차유로/열전달/구조/동특성/시스템 설계 등 개발 단계별 다양한 기법의 시뮬레이션 및 사전 검증시험 등의 중요성이 크게 부각된다. 이 글에서는 한화테크윈(혹은 HTW 로 표기)의 엔진개발 경험에 기반한 단계별 개발 시험의 종류, 필요 시험 설비 및 한화테크윈의 설비 운용 특징에 대해 소개하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.229-237
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• 2008

In this research, a MDO(multi-disciplinary design optimization) framework, which integrates aerodynamic and structural analysis to design an aircraft wing, is constructed. Whole optimization process is automated by a parametric-modeling approach. A CFD mesh is generated automatically from parametric modeling of CATIA and Gridgen followed by automatic flow analysis using Fluent. Finite element mesh is generated automatically by parametric method of MSC.Patran PCL. Aerodynamic load is transferred to Finite element model by the volume spline method. RSM(Response Surface Method) is applied for optimization, which helps to achieve global optimum. As the design problem to test the current MDO framework, a wing weight minimization with constraints of lift-drag ratio and deflection of the wing is selected. Aspect ratio, taper ratio and sweepback angle are defined as design variables. The optimization result demonstrates the successful construction of the MDO framework.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.601-608
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• 2015

The static aeroelastic analysis and optimization of flexible wings are conducted for steady state conditions while both aerodynamic and structural parameters can be used as optimization variables. The system of multidisciplinary design optimization as a robust methodology to couple commercial codes for a static aeroelastic optimization purpose to yield a convenient adaptation to engineering applications is developed. Aspect ratio, taper ratio, sweepback angle are chosen as optimization variables and the skin thickness of the wing. The real-coded adaptive range multi-objective genetic algorithm code, which represents the global multi-objective optimization algorithm, was used to control the optimization process. The support vector regression(SVR) is applied for optimization, in order to reduce the time of computation. For this multi-objective design optimization problem, numerical results show that several useful Pareto optimal designs exist for the flexible wing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.35-42
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• 2020

Electromechanical Actuator(EMA) for flight vehicles generally serves to control the fin deflection angle or the thrust vector angle. This paper deals with design and development of EMA for both aerodynamic control and thrust vector control. In this paper, a novel compact EMA is proposed that can simultaneously control both the tail fin and the jet vane with one actuator and detach the jet vane after vertical launch and rapid turn of the flight vehicle so as to increase efficiency during flying to target. To do this, we designed the EMA using a push-push link mechanism and derived a mathematical model. The mathematical model is validated by comparing simulation result and experimental data. The performance and reliability of the proposed EMA have been verified through performance test, environmental test and ground test. The proposed EMA is expected to be useful as an EMA for flight vehicles because of its simple and compact structure, as well as its performance and reliability.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.3-3
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• 1997

미사일 수직발사 시스템은 공간을 작게 차지하고 간편하여 각국이 선호하고 있다. 그러나 수직발사 초기에는 매우 낮은 속도로 상승하므로 Fin의 공력이 발생하지 않기 때문에 추력방향을 직접제어하지 않으면 안된다. 추력방향 제어장치는 Gimbal, Jet Vane, Jet Tab, Secondary Injection 등 여러 방식이 있으나 Jet Vane Type의 추력 방향 제어장치는 응답이 빠르고 경량화가 가능하며 후방 Fin과의 연동 및 작동 후 분리가 가능하다는 장점으로 인해 수직발사 미사일의 초기 방향제어에 주로 사용한다. 이 장치는 Vane이 화염 속에서 직접 구동되므로 고내열성 재료의 기술이 필요하며 미사일의 전체 System에 요구되는 Side Force를 발생시키기 위한 Vane의 최대 받음각 및 회전속도를 결정해야 한다. 따라서 초음속 유동해석을 통해서 Vane의 받음각에 대한 Side Force와 Torque를 계산하며, 구조해석을 통해 Side Force가 가해지는 동안의 Housing의 굽힘, 비틀림 하중 등을 계산하였다. 또한 Controller는 기존의 유압방식보다도 소형이며 복잡하지 않고 가격이 싼 DC Motor와 감속기를 이용하여 빠른 응답성에 부합토록 설계하였다. 본론에서는 성능과 관련된 초기 요구조건에 대한 최적설계의 변수들을 해석하고. 그에 따른 개발사양, 개발 과정, 구조, 시험방법 등에 대해 고찰하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.547-556
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• 2014

This paper discusses a one-way fluid structural interaction (FSI) analysis and shape optimization of the impeller blades for a 15,000 HP centrifugal compressor using the response surface method (RSM). Because both the aerodynamic performance and the structural safety of the impeller are affected by the shape of its blades, shape optimization is necessary using the FSI analysis, which includes a structural analysis for the induced fluid pressure and centrifugal force. The FSI analysis is performed in ANSYS Workbench: ANSYS CFX is used for the flow field and ANSYS Mechanical is used for the structural field. The response surfaces for the FSI results (efficiency, pressure ratio, maximum stress, etc.) generated based on the design of experiments (DOE) are used to find an optimal shape for the impeller blades, which provides the maximum aerodynamic performance subject to the structural safety constraints.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.24-32
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• 2006

Using a deterministic design optimization, the effect of uncertainty can result in violation of constraints and deterioration of performances. For this reason, design optimization is required to guarantee reliability for constraints and ensure robustness for an objective function under uncertainty. Therefore, this study drew Monte Carlo Simulation(MCS) for the evaluation of reliability and robustness, and selected an artificial neural network as an approximate model that is suitable for MCS. Applying to the aero-structural optimization problem of aircraft wing, we can explore robuster optima satisfying the sigma level of reliability than the baseline.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.311-320
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• 2014

Rotor blades are important devices that affect the power performance, efficiency of energy conversion, and loading and dynamic stability of wind turbines. Therefore, considering the characteristics of a wind turbine system is important for achieving optimal blade design. When a design is complete, a design evaluation should be performed to verify the structural integrity of the proposed blade in accordance with international standards or guidelines. This paper presents a detailed exposition of the evaluation items and acceptance criteria required for the design certification of wind turbine blades. It also presents design evaluation results for a 2-MW blade (KR40.1b). Analyses of ultimate strength, buckling stability, and tip displacement were performed using FEM, and Miner's rule was applied to evaluate the fatigue life of the blade. The structural integrity of the KR40.1b blade was found to satisfy the design standards.