• 제목, 요약, 키워드: analytical substructure

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Semi-analytical numerical approach for the structural dynamic response analysis of spar floating substructure for offshore wind turbine

  • Cho, Jin-Rae;Kim, Bo-Sung;Choi, Eun-Ho;Lee, Shi-Bok;Lim, O-Kaung
    • Structural Engineering and Mechanics
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    • v.52 no.3
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    • pp.633-646
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    • 2014
  • A semi-analytical numerical approach for the effective structural dynamic response analysis of spar floating substructure for offshore wind turbine subject to wave-induced excitation is introduced in this paper. The wave-induced rigid body motions at the center of mass are analytically solved using the dynamic equations of rigid ship motion. After that, the flexible structural dynamic responses of spar floating substructure for offshore wind turbine are numerically analyzed by letting the analytically derived rigid body motions be the external dynamic loading. Restricted to one-dimensional sinusoidal wave excitation at sea state 3, pitch and heave motions are considered. Through the numerical experiments, the time responses of heave and pitch motions are solved and the wave-induced dynamic displacement and effective stress of flexible floating substructure are investigated. The hydrodynamic interaction between wave and structure is modeled by means of added mass and wave damping, and its modeling accuracy is verified from the comparison of natural frequencies obtained by experiment with a 1/100 scale model.

Development, implementation and verification of a user configurable platform for real-time hybrid simulation

  • Ashasi-Sorkhabi, Ali;Mercan, Oya
    • Smart Structures and Systems
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    • v.14 no.6
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    • pp.1151-1172
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    • 2014
  • This paper presents a user programmable computational/control platform developed to conduct real-time hybrid simulation (RTHS). The architecture of this platform is based on the integration of a real-time controller and a field programmable gate array (FPGA).This not only enables the user to apply user-defined control laws to control the experimental substructures, but also provides ample computational resources to run the integration algorithm and analytical substructure state determination in real-time. In this platform the need for SCRAMNet as the communication device between real-time and servo-control workstations has been eliminated which was a critical component in several former RTHS platforms. The accuracy of the servo-hydraulic actuator displacement control, where the control tasks get executed on the FPGA was verified using single-degree-of-freedom (SDOF) and 2 degrees-of-freedom (2DOF) experimental substructures. Finally, the functionality of the proposed system as a robust and reliable RTHS platform for performance evaluation of structural systems was validated by conducting real-time hybrid simulation of a three story nonlinear structure with SDOF and 2DOF experimental substructures. Also, tracking indicators were employed to assess the accuracy of the results.

축-익 붙임 원판 계의 진동해석 (Vibration Analysis of Shaft-Bladed Disk Systems)

  • 전상복
    • 소음진동
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    • v.8 no.1
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    • pp.99-111
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    • 1998
  • An analytical method using the substructure synthesis and assumed modes method is developed to investigate the effect of flexibility of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. Then the coupled vibrations between the shaft and bladed disk are extensively investigated using simplistic models, as the shaft rotational speed and the pretwist and stagger angles of blade are varied.

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Ni-36.5at.%Al 합금에서 V 첨가가 파괴거동 및 마르텐사이트 내부조직에 미치는 영향 (The Influence of Vanadium Addition on Fracture Behavior and Martensite Substructure in a Ni-36.5at.%Al Alloy)

  • 김영도;최주
    • 분석과학
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    • v.5 no.2
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    • pp.203-211
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    • 1992
  • Ni-36.5at.%Al 합금에서 결정립계에서의 scavenging 원소로 알려진 V를 첨가하여 이 합금의 파괴거동 및 마르텐사이트 미세조직에 미치는 V의 영향에 대해 조사하였다. 시편의 파단면은 주사전자현미경으로 관찰하였고 EDX spectrometer를 사용하여 파단면의 조성을 분석하였으며 투과전자현미경으로 마르텐사이트 내부조직의 변화에 대해 조사하였다. V의 첨가로 입계파괴에서 입내파괴로 파괴 모드의 변화를 나타내었으며 EDX spectrometer로 분석한 결과 입내에 비해 입계에 Al의 함량이 상대적으로 증가되는 양상을 보여 주었다. Ni-36.5at.%Al 합금의 경우 마르텐사이트 플레이트는 내부쌍정으로 이루어져 있으나 V의 첨가에 따라 twinned 마르텐사이트 조직은 사라지며 stacking fault와 고밀도의 전위를 가진 modulated 조직이 점차 지배적으로 형성되는 것이 관찰되었다. Stacking fault를 분석한 결과 Al과 V의 치환에 따른 extrinsic fault였으며 high-energy 상태인 이 stacking fault가 있는 부위에 유해 원소인 S가 편석됨으로써 결정립계에서의 파괴를 줄일 수 있었다.

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전달강성계수법과 부분구조합성법을 이용한 구조물의 진동해석 (Vibration Analysis of Structures Using the Transfer Stiffness Coefficient Method and the Substructure Synthesis Method)

  • 최명수
    • 한국동력기계공학회지
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    • v.5 no.4
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    • pp.24-30
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    • 2001
  • The substructure synthesis method(SSM) is developed for overcoming disadvantages of the Finite Element Method(FEM). The concept of the SSM is as follows. After dividing a whole structure into several substructures, every substructures are analyzed by the FEM or experiment. The whole structure is analyzed by using connecting condition and the results of substructures. The concept of the transfer stiffness coefficient method(TSCM) is based on the transfer of the nodal stiffness coefficients which are related to force vectors and displacement vectors at each node of analytical mode1. The superiority of the TSCM to the FEM in the computation accuracy, cost and convenience was confirmed by the numerical computation results. In this paper, the author suggests an efficient vibration analysis method of structures by using the TSCM and the SSM. The trust and the validity of the present method is demonstrated through the numerical results for computation models.

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매입구조물(埋入構造物)과 층상지반상(層狀地盤上) 구조물(構造物)에 대한 지반(地盤)-구조물(構造物) 상호(相互) 작용(作用)의 단순해석(單純解析) (A Simplified Soil-Structure Interaction Analytical Technique of Embedded Structure and Structure on Layered Soil Sites)

  • 조양희;이용일;김종수
    • 대한토목학회논문집
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    • v.7 no.2
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    • pp.45-57
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    • 1987
  • 지진하중(地震荷重)에 대한 구조물(構造物)의 동적(動的) 거동(擧動)은 지반(地盤)의 특성(特性)에 따라 현저한 차이(差異)를 나타내게 되는데 이러한 현상(現象)을 동적(動的) 지반(地盤)-구조물(構造物) 상호작용(相互作用)이라고 한다. 지반(地盤)-구조물(構造物) 상호작용(相互作用)의 해석방법(解析方法)은 크게 직접법(直接法)과 부분구조법(部分構造法)으로 구분되며, 이 중 부분구조법(部分構造法)은 직접법(直接法)에 비하여 해석방법(解析方法)은 간편하지만 매입구조물(埋入構造物)이나 층상지반상(層狀地盤上) 구조물(構造物)에 대한 해석 시 많은 제약(制約)을 받게 된다. 본 논문(論文)에서는 원친적으로 반무한탄성체지반상(半無限彈性體地盤上) 구조물(構造物)에만 효과적으로 적용(適用)할 수 있는 부분구조법(部分構造法)을 적절히 응용(應用)하여 매입구조물(埋入構造物) 혹은 층상지반상(層狀地盤上) 구조물(構造物)에도 적용할 수 있는 방법을 제시(提示)하였으며, 직접법(直接法)에 의한 해석프로그램인 FLUSH의 해석결과와 비교(比較) 검토(檢討)하여 그 타당성(妥當性)을 입증(立證)하였다.

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부분구조응답함수감소법을 이용한 동적구조변경 (Structural Dynamic Modification Using substructure Response Function Sensitivity Method(SRFSM))

  • 지태한;박영필
    • 대한기계학회논문집A
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    • v.20 no.12
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    • pp.3782-3791
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    • 1996
  • A great deal of effert has been invested in upgrading the performance and the efficiency of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, this performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircraft, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure based on that of the composing structures, are widely used. By llinking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned structures can be desinged. In this paper, a new algorithm for structural dynamic modification-SRFSM (substructure response function sensitivity method) is proposed by linking frequency responce function synthesis and response function sensitivity. A mehtod to obtain response function sensitivity using direct derivative of mechanical impedance, is also used.

다중동조질량감쇠기를 이용한 단순지지 슬래브의 진동 및 소음저감에 관한 연구 (Vibration and Noise Control of the Simply Supported Slab Using the Multi-tuned Mass Damper)

  • 황재승;홍건호;박홍근
    • 한국소음진동공학회논문집
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    • v.18 no.10
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    • pp.1006-1013
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    • 2008
  • In this study, it is outlined that heavy weight floor impact noise induced by the vibration of slab can be reduced using multi tuned mass damper(MTMD) effectively. Substructure synthesis is utilized to develope analytical model of the slab coupled with MTMD and acoustic power is introduced to evaluate the performance of noise control for simplicity. Numerical analysis is carried out to investigate the effect of the properties of MTMD on the vibration and noise control of the simply supported slab. Numerical analysis shows that mass ratio of MTMD is critical on the vibration and noise control of the slab and it is also essential to reduce the vibration in higher modes of slab in the light of its great effect on the radiation of sound.

다중질량감쇠기를 이용한 슬래브의 진동 및 소음저감에 관한 연구 (Vibration and noise control of slab using the multi-tuned mass damper)

  • 황재승;김홍진;강경수;홍건호
    • 한국소음진동공학회:학술대회논문집
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    • pp.659-664
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    • 2008
  • In this study, it is outlined that heavy weight floor impact noise induced by the vibration of slab can be reduced by multi tuned mass damper(MTMD) effectively. Substructure synthesis is utilized to develope analytical model of slab coupled with MTMD and acoustic power is introduced to evaluate the performance of noise control for simplicity. Numerical analysis is carried out to investigate the effect of the properties of MTMD on the vibration and noise control. Numerical analysis shows that mass ratio of MTMD is critical on the vibration and noise control of the slab and it is essential to reduce the vibration in higher modes of slab because it has a great effect on the radiation of sound.

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Seismic performance of a rocking bridge pier substructure with frictional hinge dampers

  • Cheng, Chin-Tung;Chen, Fu-Lin
    • Smart Structures and Systems
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    • v.14 no.4
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    • pp.501-516
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    • 2014
  • The rocking pier system (RPS) allows the columns to rock on beam or foundation surfaces during the attacks of a strong earthquake. Literatures have proved that seismic energy dissipated by the RPS through the column impact is limited. To enhance the energy dissipation capacity of a RPS bridge substructure, frictional hinge dampers (FHDs) were installed and evaluated by shaking table tests. The supplemental FHDs consist of two brass plates sandwiched by three steel plates. The strategy of self-centering design is to isolate the seismic energy by RPS at the columns and then dissipate the energy by FHDs at the bridge deck. Component tests of FHD were first conducted to verify the friction coefficient and dynamic characteristic of the FHDs. In total, 32 shaking table tests were conducted to investigate parameters such as wave forms of the earthquake (El Centro 1940 and Kobe 1995) and normal forces applied on the friction dampers. An analytical model was also proposed to compare with the tested damping of the bridge sub-structure with or without FHDs.