• Title/Summary/Keyword: Substructure Method

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Dynamic Analysis of Harmonically Excited Non-Linear Structure System Using Harmonic Balance Method

  • Mun, Byeong-Yeong;Gang, Beom-Su;Kim, Byeong-Su
    • Journal of Mechanical Science and Technology
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    • v.15 no.11
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    • pp.1507-1516
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    • 2001
  • An analytical method is presented for evaluation of the steady state periodic behavior of nonlinear structural systems. This method is based on the substructure synthesis formulation and a harmonic balance procedure, which is applied to the analysis of nonlinear responses. A complex nonlinear system is divided into substructures, of which equations are approximately transformed to modal coordinates including nonlinear term under the reasonable procedure. Then, the equations are synthesized into the overall system and the nonlinear solution for the system is obtained. Based on the harmonic balance method, the proposed procedure reduces the size of large degrees-of-freedom problem in the solving nonlinear equations. Feasibility and advantages of the proposed method are illustrated using the study of the nonlinear rotating machine system as a large mechanical structure system. Results obtained are reported to be an efficient approach with respect to nonlinear response prediction when compared with other conventional methods.

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Dynamic Analysis of Harmonically Excited Non-Linear System Using Multiple Scales Method

  • Moon, Byung-Young;Kang, Beom-Soo
    • Journal of Mechanical Science and Technology
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    • v.16 no.6
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    • pp.819-828
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    • 2002
  • An analytical method is presented for evaluation of the steady state periodic behavior of nonlinear systems. This method is based on the substructure synthesis formulation and a MS (multiple scales) procedure, which is applied to the analysis of nonlinear responses. The proposed procedure reduces the size of large degrees-of-freedom problem in solving nonlinear equations. Feasibility and advantages of the proposed method are illustrated with the nonlinear rotating machine system as an example of large mechanical structure systems. In addition, its efficiency for nonlinear response prediction will be shown by comparison of other conventional methods.

Nonlinear System Parameter Identification Using Finite Element Model (유한요소모델을 이용한 비선형 시스템의 매개변수 규명)

  • Kim, Won-Jin;Lee, Bu-Yun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.6 s.177
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    • pp.1593-1600
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    • 2000
  • A method based on frequency domain approaches is presented for the nonlinear parameters identification of structure having nonlinear joints. The finite element model of linear substructure is us ed to calculating its frequency response functions needed in parameter identification process. This method is easily applicable to a complex real structure having nonlinear elements since it uses the frequency response function of finite element model. Since this method is performed in frequency domain, the number of equations required to identify the unknown parameters can be easily increased as many as it needed, just by not only varying excitation amplitude but also selecting excitation frequencies. The validity of this method is tested numerically and experimentally with a cantilever beam having the nonlinear element. It was verified through examples that the method is useful to identify the nonlinear parameters of a structure having arbitary nonlinear boundaries.

Structural Dynamic Analysis using Multi-FRF Synthesis Method (다중전달 함수합성법을 이용한 구조물의 동특성 해석)

  • 정재훈;지태한;박영필
    • Journal of KSNVE
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    • v.8 no.1
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    • pp.139-145
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    • 1998
  • A great deal of effort has been invested in upgrading the performance and the efficiency of dynamic analysis of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, the performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircrafts, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure are widely used. Through linking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned strucutres can be proposed. In this study, a new algorithm of substructre synthesis method, Multi-FRF synthesis method, is proposed to analyze a structure composed of many substructures.

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A Study on the Bending Analysis of Rectangular Plates by Substructuring Technique (분할구조기법을 이용한 장방형판의 휨해석에 관한 연구)

  • 오숙경;김성용;김일중;이용수
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1997.10a
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    • pp.65-72
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    • 1997
  • This study is the bending analysis of rectangular plates with 4-sides simply supported by Finite Element Method using substructuring technique. In finite element method, as the more number of finite element, the more dimension of matrix, it is difficult to obtain accuracy solution. In this paper substructuring technique is applied to finite element method in order to reduce the dimension of matrix according to the number of finite element mesh. To validate finite element method using substructuring technique, deflections and moments of rectangular plates by that method is compared with those of references. Considering the symmetry of the plate and load, one fourth of plate is analyzed. Operating time and the error of solutions according to the number of finite element mesh and substructure are compared with each other.

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Reliability analysis of steel cable-stayed bridges including soil-pile interaction

  • Cheng, Jin;Liu, Xiao-luan
    • Steel and Composite Structures
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    • v.13 no.2
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    • pp.109-122
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    • 2012
  • An efficient and accurate algorithm is proposed to evaluate the reliability of cable-stayed bridges accounting for soil-pile interaction. The proposed algorithm integrates the finite-element method and the response surface method. The finite-element method is used to model the cable-stayed bridge including soil-pile interaction. The reliability index is evaluated based on the response surface method. Uncertainties in the superstructure, the substructure and load parameters are incorporated in the proposed algorithm. A long span steel cable-stayed bridge with a main span length of 1088 m built in China is considered as an illustrative example. The reliability of the bridge is evaluated for the strength and serviceability performance functions. Results of the study show that when strength limit states for both girder and tower are considered, soil-pile interaction has significant effects on the reliability of steel cable-stayed bridges. Further, a detailed sensitivity study shows that the modulus of subgrade reaction is the most important soil-pile interaction-related parameter influencing the reliability of steel cable-stayed bridges.

Method for Determining Thickness of Rubber Fenders of a Tripod Type Offshore Wind Turbine Substructure (해상풍력 삼각지주형 하부구조물의 충격손상방지용 고무펜더의 두께결정 방법)

  • Lee, Kang-Su
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.4
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    • pp.490-496
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    • 2012
  • The main object of this research is to minimize the shock effects which frequently result in fatal damage in offshore wind turbine on impact of barge. The collision between offshore wind turbine and barge is generally a complex problem and it is often impractical to perform rigorous finite element analyses to include all effects and sequences during the collision. On applying the impact force of a barge to the offshore wind turbine, the maximum acceleration, internal energy, and plastic strain are calculated for each load case using the finite element method. A parametric study is conducted with the experimental data in terms of the velocity of barge, thickness of the offshore wind turbine, and thickness and Mooney-Rivlin coefficient of the rubber fender. Through the analysis proposed in this study, it is possible to determine the proper size and material properties of the rubber fender and the optimal moving conditions of barge.

Study of geological structure in area of Hwasan caldera using geophysical method (지구물리학적 방법에 의한 화산 칼데라 지역의 지질구조 연구)

  • Kwon, Byung-Doo;Lee, Heui-Soon;Yang, Joon-Mo;Park, Gye-Soon;Eom, Joo-Young;Kim, Dong-Oh
    • 한국지구물리탐사학회:학술대회논문집
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    • 2007.06a
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    • pp.267-272
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    • 2007
  • Uiseong subbasin belonging to Kyungsang basin resulted from volcanic activity in the late Cretaceous. In this study, we carry out MT and gravity survey at the Hwasan caldera, which was formed of volcanic and abyssal rocks complex, then analyze and identify geological substructure. Potential survey such as gravity and magnetic survey has been mainly carried out in former studies, so depth information for understanding substructure was not enough. To complement a potential survey, we use MT method, which has high vertical resolution. Moreover we make a simple 2D model comparing with former study. The result of MT and gravity 2D modeling shows that this area is roughly composed of 3 layers; The bottom layer is a basement. In the second layer, intrusive rocks having high resistivity is placed along the ring faults and the sedimentary layer of low resistivity is inside caldera. The highest layer is alluvium. To comprehend the 3D structure of the Hwasan caldera, we perform 3D gravity inversion, and construct the 3D model from the result of 3D gravity inversion. MT responses are calculated by using the constructed 3D model and the 3D model of the Hwasan caldera's structure is suggested after comparing the calculated values with the observed values at MT line.

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Creep Properties of Squeeze Infiltrated AS52 Mg/Al18B4O33w Composite (용탕가압침투 AS52 Mg/Al18B4O33w 복합재료의 크리프 특성)

  • Choi, Kye-Won;Park, Yong-Ha;Park, Bong-Gyu;Park, Yong-Ho;Park, Ik-Min;Cho, Kyung-Mox
    • Korean Journal of Metals and Materials
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    • v.46 no.7
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    • pp.412-419
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    • 2008
  • Creep behavior of the squeeze infiltrated AS52 Mg matrix composites reinforced with 15 vol% of aluminum borate whiskers($Al_{18}B_4O_{33}w$) fabricated squeeze infiltration method was investigated. Microstructure of the composites was observed as uniformly distributed reinforcement in the matrix without any particular defects of casting pores etc.. Creep test was carried out at the temperature of 150 and $200^{\circ}C$ under the applied stress range of 60~120 MPa. The creep resistance of the composite was significantly improved comparing with the unreinforced AS52 Mg alloy. The creep behavior of composites might be interpreted with the substructure invariant model successfully for the composite. Threshold stress of the composite exist for the creep deformation of the composite. The analysis of the creep behavior of the composite with threshold stress indicated that creep deformation was controlled by the lattice diffusion process of AS52 Mg matrix at given effective stresses and temperatures. Activation energy was also calculated to check lattice diffusion controlled creep behavior of the composite.

Arching Action Effect for Inelastic Seismic Responses of Bridge Structures (교량의 비탄성 지진응답에 대한 아칭작용의 영향)

  • Song, Jong-Keol;Nam, Wang-Hyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.2A
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    • pp.131-143
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    • 2009
  • Under transverse earthquake shaking, arching action of bridge structures develops along the deck between the abutments thus providing the so-called deck resistance. The magnitude of the arching action for bridge structures is dependent on the number of spans, connection condition between deck and abutment or piers, and stiffness ratio between superstructure and substructure. In order to investigate the arching action effects for inelastic seismic responses of PSC Box bridges, seismic responses evaluated by pushover analysis, capacity spectrum analysis and nonlinear time-history analysis are compared for 18 example bridge structures with two types of span numbers (short bridge, SB and long bridge, LB), three types of pier height arrangement (regular, semi-regular and irregular) and three types of connection condition between superstructure and substructure (Type A, B, C). The arching action effects (reducing inelastic displacement and increasing resistance capacity) for short bridge (SB) is more significant than those for long bridge (LB). Semi-regular and irregular bridge structures have more significant arching action than regular bridges.