• Title/Summary/Keyword: Guyan reduction method

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Investigation of the accuracy of different finite element model reduction techniques

  • Ghannadi, Parsa;Kourehli, Seyed Sina
    • Structural Monitoring and Maintenance
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    • v.5 no.3
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    • pp.417-428
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    • 2018
  • In this paper, various model reduction methods were assessed using a shear frame, plane and space truss structures. Each of the structures is one-dimensional, two-dimensional and three-dimensional, respectively. Three scenarios of poor, better, and the best were considered for each of the structures in which 25%, 40%, and 60% of the total degrees of freedom (DOFs) were measured in each of them, respectively. Natural frequencies of the full and reduced order structures were compared in each of the numerical examples to assess the performance of model reduction methods. Generally, it was found that system equivalent reduction expansion process (SEREP) provides full accuracy in the model reduction in all of the numerical examples and scenarios. Iterated improved reduced system (IIRS) was the second-best, providing acceptable results and lower error in higher modes in comparison to the improved reduced system (IRS) method. Although the Guyan's method has very low levels of accuracy. Structures were classified with the excitation frequency. High-frequency structures compared to low-frequency structures have been poor performance in the model reduction methods (Guyan, IRS, and IIRS).

A STUDY ON THERMAL MODEL REDUCTION ALGORITHM FOR SATELLITE PANEL (인공위성 패널 열해석모델 간소화 알고리즘 연구)

  • Kim, Jung-Hoon;Jun, Hyoung Yoll;Kim, Seung Jo
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.9-15
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    • 2012
  • Thermal model reduction algorithms and techniques are introduced to condense a huge satellite panel thermal model into the simplified model on the purpose of calculating the thermal responses of a satellite on orbit. Guyan condensation algorithm with the substitution matrix manipulation is developed and the mathematical procedure is depicted step by step. A block-form LU decomposition method is also invited to compare the developed algorithm. The constructed reduced thermal model induced from the detailed model based on a real satellite panel is satisfying the correlation criterion of ${\pm}2^{\circ}C$ for the validity accuracy. Guyan condensation algorithm is superior to the block-form LU decomposition method on computation time.

Sub-structuring Technique of High-speed Train-bridge Interaction Analysis for Foundation Design (기초 설계를 위한 고속철도 교량-열차 상호작용 해석의 부구조화 기법)

  • Lee, Kang-Il;Song, Myung-Kwan
    • Journal of the Korean Geosynthetics Society
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    • v.20 no.2
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    • pp.35-43
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    • 2021
  • In this paper, the sub-structuring technique-applied train-bridge interaction analysis model, which is formulated based on the simplified three-dimensional train-bridge interaction analysis model for high-speed bridge-train interaction analysis, is presented. In the sub-structuring technique, the super-structure and the supporting structure of railway bridges can be modeled as sub-structures, and train-bridge interaction analysis can be efficiently performed. As a train analysis model, two-dimensional train model is used, and the Lagrange equation of motion is applied to derive the equation of motion of two-dimensional train. In the sub-structuring technique, the number of degrees of freedom can be reduced by using the condensation method, thus reducing the time and cost for calculating the eigenvalues and eigenvectors, and the time and cost for the subsequent calculation. In this paper, Guyan reduction method is used as sub-structuring technique. By combining simplified three-dimensional bridge-train interaction analysis and Guyan reduction method, the efficient and accurate bridge-train interaction analysis can be performed.

A Vibration Analysis Model for Bellows in the Vehicle Exhaust System Using Method of Reduced Degree of Freedom (자유도 저감법을 이용한 자동차 배기시스템의 벨로우즈 진동해석)

  • Shim, Dong-Hyouk;Kim, Dae-Hyun;Choi, Myung-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.304-308
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    • 2006
  • The focus of this study is modeling technique for a bellows in vehicle exhaust system. Bellows was developed using tile finite element model by replacing with the equivalent beam. The equivalent beam model were studied in detail. Non-structural node in the cross section of original model is given to expressing their motion. Equivalent mass matrix and stiffness matrix calculated using Guyan reduction method. Material Properties of beam was obtained from the direct comparison between equivalent model and that of Timoshenko beam model. The calculated natural frequencies and mode shape are compared with the reference results and coincided well. The results were compared with the confirmed results, which were in good agreement.

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A Dynamic Condensation for Tall Buildings with Active Tuned Mass Damper (능동 동조질량감쇠의 고층빌딩 해석을 위한 동적압축법)

  • Jung, Yang-Ki;Qu, Zu Qing
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.2 s.48
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    • pp.21-29
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    • 2006
  • It is impractical to install sensors on every floor of a tall building to measure the full state vector because of the large number of degrees of freedom. This makes it necessary to introduce reduced order control. A kind of system reduction scheme (dynamic condensation method) is proposed in this paper. This method is iterative and Guyan condensation is looked upon as an initial approximation of the iteration. Since the reduced order system is updated repeatedly until a desired one is obtained, the accuracy of the reduced order system resulting from the proposed method is much higher than that obtained from the Guyan condensation method. An eigenvalue shilling technique is applied to accelerate the convergence of Iteration. Two schemes to establish the reduced order system by using the proposed method are also presented and discussed in this paper. The results for a tail building with active tuned mass damper show that the proposed method is efficient for the reduced order modelling and the accuracy is very close to exact only after two iterations.

An efficient modeling technique for floor vibration in multi-story buildings

  • Lee, Dong-Guen;Ahn, Sang-Kyoung;Kim, Jinkoo
    • Structural Engineering and Mechanics
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    • v.10 no.6
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    • pp.603-619
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    • 2000
  • Analysis of a framed structure for vertical vibration requires a lot of computational efforts because large number of degrees of freedom are generally involved in the dynamic responses. This paper presents an efficient modeling technique for vertical vibration utilizing substructuring technique and super elements. To simplify the modeling procedure each floor in a structure is modeled as a substructure. Only the vertical translational degrees of freedom are selected as master degrees of freedom in the inside of each substructure. At the substructure-column interface, horizontal and rotational degrees of freedom are also included considering the compatibility condition of slabs and columns. For further simplification, the repeated parts in a substructure are modeled as super elements, which reduces computation time required for the construction of system matrices in a substructure. Finally, the Guyan reduction technique is applied to enhance the efficiency of dynamic analysis. In numerical examples, the efficiency and accuracy of the proposed method are demonstrated by comparing the response time histories and the analysis time.

Substructure Synthesis Method using Dynamic Reduction (동축소법을 이용한 부분구조합성법)

  • 박석주;박성현;김성우
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.1
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    • pp.82-87
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    • 2000
  • The component mode synthesis method(CMS) used for vibration analysis has demerit that error becomes larger, as degree of natural frequency grows higher. The reason of error occurrence is that Guyan's static reduction is used and the number of modes taken in each component is deficient. This paper proposes the substructure synthesis method using dynamic reduction to solve the problem from the component mode synthesis method. Computer simulation for the proposed method. FEM and the component mode synthesis method(CMS) on a rectrangular plate has been carried out to prove the avilability of the proposed method.

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A Development of the Tire Interfacing Using the Reduction Method (모델 축소법을 이용한 타이어 인터페이싱 개발)

  • 임문수;김영배;조규종;정광용
    • Korean Journal of Computational Design and Engineering
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    • v.8 no.2
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    • pp.109-114
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    • 2003
  • In order to develop the reduced tire modal model for analyzing a full tire model, the Craig-Bampton method is utilized in this paper. When the tire contacts the road, the Abaqus solver extracts the condensed stiffness, coupled mass and mode shape matrix about the node, which contacts the road. The Abaqus full tire model is reduced using the substructure method utilizing Craig-Bampton algorithm. Then, the extracted matrices are interfaced with the superelement, which is fed to the Nastran reduction algorithm. Eventually, the reduced tire model is verified from experiment and various reduction parameters (i.e. modal number, reduction point, etc.) are studied for the effectiveness of the proposed paper.

Analysis of Structural joints Using Flexibility Influence Coefficient (유연성 영향 계수를 이용한 구조물의 결합부 해석)

  • 이재운;고강호;이수일;이장무
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.831-836
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    • 1994
  • This paper presents rational modeling and analysis method for complex structures with various structural joints. For modeling of structural joint, a general modeling technique is newly proposed by flexibility influence coefficient and inverse of flexibility matrix and static reduction concept which is applied to the retained DOFs(degrees of freedom) of detailed finite element model of struction joints. By this method,joint model with contact surface. which can not be reduced by the general reduction theory such as Guyan reduction theory ,can be reduced effectively. And in this method, the nonlinearity of the contact surface can be linearized within a proper range and the boundary effects of joint region can be excluded. Using the proposed method, screwed joint,glued joint and bolted joint are analyzed. And the effectiveness of the proposed method is verified by experiments.

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Equivalent Coefficient Element Modelling for a Jointed Structure Using the Reduction of Flexibility and Mass Matrices (유연도행렬 및 질량관성행렬의 축약을 이용한 결합체결 구조부의 등가 계수행렬 요소 모델링)

  • Choi, Y.H.;Shin, J.H.;Chung, W.J.;Park, J.K.;Cho, J.H.
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.655-660
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    • 2000
  • This paper presents the construction of consistent coefficient matrix elements for jointed structures using the reduction of flexibility and mass matrices. The reduced flexibility coefficient matrix hat little structural complexity than Guyan's stiffness matrix reduction since the only element of the original matrix, corresponding to the selected nodal degrees of freedom, contributes. The proposed method was applied to building equivalent coefficient matrices for a clamp jointed structure in finite element modal analysis of a cantilevered beam. The theoretical analysis results were compared with those experimental modal analysis, Comparison of both shows good agreement each other.

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