• 제목/요약/키워드: Hybrid Structures

검색결과 989건 처리시간 0.021초

설계요구조건 검증을 통한 한국형 고속 틸팅열차(TTX)의 차체 재료 선정에 관한 연구 (A Study on Material Selection of the Carbody Structure of Korean Tilting Train express(TTX) through the Verification of Design Requirements)

  • 신광복;구동회;한성호;박기진
    • 한국철도학회논문집
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    • 제7권2호
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    • pp.77-84
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    • 2004
  • In order to determine the most suitable material system for achieving the lightweight design while fulfilling the design requirements of carbody structures of Korean Tilting Train eXpress(TTX), aluminum carbody. composite carbody, and hybrid carbody combined with aluminum and composite structures were considered in the present study. The finite-element analysis was used to verify the design requirements or the TTX carbody structures with the material system considered in the design stages. The stresses in the carbody structures and deflections of underframe against static load cases were used as design criteria. The results show that the hybrid carbody structures are beneficial with regard to weight savings and structural integrity in comparison to aluminum and composite carbody structures.

Real-time hybrid testing using model-based delay compensation

  • Carrion, Juan E.;Spencer, B.F. Jr.
    • Smart Structures and Systems
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    • 제4권6호
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    • pp.809-828
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    • 2008
  • Real-time hybrid testing is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with time-dependent components. Real-time hybrid testing is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for time delays and actuator time lag is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid testing in which time delay/lag compensation is implemented using model-based response prediction. The efficacy of the proposed strategy is verified by conducting substructure real-time hybrid testing of a steel frame under earthquake loads. For the initial set of experiments, a specimen with linear-elastic behavior is used. Experimental results agree well with the analytical solution and show that the proposed approach and testing system are capable of achieving a time-scale expansion factor of one (i.e., real time). Additionally, the proposed method allows accurate testing of structures with larger frequencies than when using conventional time delay compensation methods, thus extending the capabilities of the real-time hybrid testing technique. The method is then used to test a structure with a rate-dependent energy dissipation device, a magnetorheological damper. Results show good agreement with the predicted responses, demonstrating the effectiveness of the method to test rate-dependent components.

Real-time large-scale hybrid testing for seismic performance evaluation of smart structures

  • Mercan, Oya;Ricles, James;Sause, Richard;Marullo, Thomas
    • Smart Structures and Systems
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    • 제4권5호
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    • pp.667-684
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    • 2008
  • Numerous devices exist for reducing or eliminating seismic damage to structures. These include passive dampers, semi-active dampers, and active control devices. The performance of structural systems with these devices has often been evaluated using numerical simulations. Experiments on structural systems with these devices, particularly at large-scale, are lacking. This paper describes a real-time hybrid testing facility that has been developed at the Lehigh University NEES Equipment Site. The facility enables real-time large-scale experiments to be performed on structural systems with rate-dependent devices, thereby permitting a more complete evaluation of the seismic performance of the devices and their effectiveness in seismic hazard reduction. The hardware and integrated control architecture for hybrid testing developed at the facility are presented. An application involving the use of passive elastomeric dampers in a three story moment resisting frame subjected to earthquake ground motions is presented. The experiment focused on a test structure consisting of the damper and diagonal bracing, which was coupled to a nonlinear analytical model of the remaining part of the structure (i.e., the moment resisting frame). A tracking indictor is used to track the actuator ability to achieve the command displacement during a test, enabling the quality of the test results to be assessed. An extension of the testbed to the real-time hybrid testing of smart structures with semi-active dampers is described.

Hybrid bolt-loosening detection in wind turbine tower structures by vibration and impedance responses

  • Nguyen, Tuan-Cuong;Huynh, Thanh-Canh;Yi, Jin-Hak;Kim, Jeong-Tae
    • Wind and Structures
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    • 제24권4호
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    • pp.385-403
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    • 2017
  • In recent years, the wind energy has played an increasingly important role in national energy sector of many countries. To harvest more electric power, the wind turbine (WT) tower structure becomes physically larger, which may cause more risks during long-term operation. Associated with the great development of WT projects, the number of accidents related to large-scaled WT has also been increased. Therefore, a structural health monitoring (SHM) system for WT structures is needed to ensure their safety and serviceability during operational time. The objective of this study is to develop a hybrid damage detection method for WT tower structures by measuring vibration and impedance responses. To achieve the objective, the following approaches are implemented. Firstly, a hybrid damage detection scheme which combines vibration-based and impedance-based methods is proposed as a sequential process in three stages. Secondly, a series of vibration and impedance tests are conducted on a lab-scaled model of the WT structure in which a set of bolt-loosening cases is simulated for the segmental joints. Finally, the feasibility of the proposed hybrid damage detection method is experimentally evaluated via its performance during the damage detection process in the tested model.

Analytical and numerical algorithm for exploring dynamic response of non-classically damped hybrid structures

  • Raheem, Shehata E. Abdel
    • Coupled systems mechanics
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    • 제3권2호
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    • pp.171-193
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    • 2014
  • The dynamic characterization is important in making accurate predictions of the seismic response of the hybrid structures dominated by different damping mechanisms. Different damping characteristics arise from the construction of hybrid structure with different materials: steel for the upper part; reinforced concrete for the lower main part and interaction with supporting soil. The process of modeling damping matrices and experimental verification is challenging because damping cannot be determined via static tests as can mass and stiffness. The assumption of classical damping is not appropriate if the system to be analyzed consists of two or more parts with significantly different levels of damping. The dynamic response of structures is critically determined by the damping mechanisms, and its value is very important for the design and analysis of vibrating structures. A numerical algorithm capable of evaluating the equivalent modal damping ratio from structural components is desirable for improving seismic design. Two approaches are considered to explore the dynamic response of hybrid tower of cable-stayed bridges: The first approach makes use of a simplified model of 2 coupled lumped masses to investigate the effects of subsystems different damping, mass ratio, frequency ratio on dynamic characteristics and equivalent modal damping; the second approach employs a detailed numerical step-by step integration procedure.

금속재 차체와 하이브리드 복합재 차체와의 설계기술 비교 연구 (A Comparative Study on the Design Techniques of Metal and Hybrid Composite Carbody Structures in Railway Vehicle System)

  • 신광복;전승기;천준호;이승영
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2004년도 추계학술발표대회 논문집
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    • pp.207-211
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    • 2004
  • There are the marked differences between the design techniques of carbody structures made of composite materials and metal materials. The design techniques of carbody structures made of metal materials have already been guaranteed in the domestic field. But, in case of the hybrid composite carbody structures, it is the first attempt to be developed and there is no experience of the design in the railway applications. In this paper, the design techniques of hybrid composite structures were introduced and compared with that of the conventional metal carbody.

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Thermal Characteristics of Hybrid Insert for Carbon Composite Satellite Structures

  • Lim, Jun Woo
    • Composites Research
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    • 제28권4호
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    • pp.162-167
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    • 2015
  • Composite sandwich structures are widely employed in various applications, due to their high specific stiffness and specific bending strength compared to solid panels. Lately, for that reason, the advanced composite sandwich structures are employed in satellite structures: materials should be as light as possible with the highest attainable performance. This study is majorly focused on inserts employed to the composite sandwich satellite structures. A new hybrid insert design was developed in precedent study to reduce the mass of the sandwich structure since the mass of the satellite structure is related to high launching cost [1]. In this study, the thermal characteristics and behavior of the precedently developed hybrid insert with carbon composite reinforcing web and the conventional partial insert were numerically investigated.

나노입자 마스크를 이용하여 제작한 초소수성 마이크로-나노 혼성구조 (Fabrication of Superhydrophobic Micro-Nano Hybrid Structures by Reactive Ion Etching with Au Nanoparticle Masks)

  • 이초연;윤석본;장건익;윤완수
    • 한국진공학회지
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    • 제19권4호
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    • pp.300-306
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    • 2010
  • 소수성 고분자를 사용하여 제작한 마이크로구조에 금 나노입자를 마스크로 이용하는 반응성이온식각(RIE: Reactive Ion Etching)을 적용하여 초소수성을 갖는 마이크로-나노 혼성구조를 제작하였다. 소수성 고분자로는 PFPE (perfluoropolyether bisurethane methacrylate)를 사용하였으며 마이크로 단일구조는 PDMS (polydimethylsiloxane) 몰드를 사용하는 스탬핑 방식으로 제작하였다. 다양한 형태로 제작한 PFPE 마이크로 단일구조와 마이크로-나노 혼성구조의 표면 접촉각을 측정하여 표면 미세구조에 따른 소수성의 변화를 관찰하였다. 마이크로 단일구조의 경우 접촉각은 안정적인 값을 보이지 못하였으나 단일 구조에 나노입자를 사용한 식각을 적용해 나노구조가 형성됨에 따라 $150^{\circ}$ 이상의 접촉각을 갖는 초소수성 표면이 매우 높은 재현성으로 용이하게 형성되었다.

HYBRID POWER FLOW ANALYSIS USING SEA PARAMETERS

  • Park, Y.H.;Hong, S.Y.
    • International Journal of Automotive Technology
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    • 제7권4호
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    • pp.423-439
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    • 2006
  • This paper proposes a hybrid analytic method for the prediction of vibrational and acoustic responses of reverberant system in the medium-to-high frequency ranges by using the PFA(Power Flow Analysis) algorithm and SEA(Statistical Energy Analysis) coupling concepts. The main part of this method is the application of the coupling loss factor(CLF) of SEA to the boundary condition of PFA in reverberant system. The hybrid method developed shows much more promising results than the conventional SEA and equivalent results to the classical PFA for various damping loss factors in a wide range of frequencies. Additionally, this paper presents applied results of hybrid power flow finite element method(hybrid PFFEM) by formulating the new joint element matrix with CLF to analyze the vibrational responses of built-up structures. Finally, the analytic results of coupled plate structures and an automobile-shaped structure using hybrid PFFEM were predicted successively.

Seismic performance evaluation of moment frames with slit-friction hybrid dampers

  • Lee, Joonho;Kim, Jinkoo
    • Earthquakes and Structures
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    • 제9권6호
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    • pp.1291-1311
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    • 2015
  • This study investigates the seismic energy dissipation capacity of a hybrid passive damper composed of a friction and a hysteretic slit damper. The capacity of the hybrid device required to satisfy a given target performance of a reinforced concrete moment resisting frame designed with reduced design base shear is determined based on the ASCE/SEI 7-10 process, and the seismic performances of the structures designed without and with the hybrid dampers are verified by nonlinear dynamic analyses. Fragility analysis is carried out to investigate the probability of a specified limit state to be reached. The analysis results show that in the structure with hybrid dampers the residual displacements are generally reduced and the dissipated inelastic energy is mostly concentrated on the dampers. At the Moderate to Extensive damage states the fragility turned out to be smallest in the structure with the hybrid dampers.