• Title/Summary/Keyword: 리츠벡터

Search Result 6, Processing Time 0.027 seconds

Reduction Method based on Sub-domain Structure using Reduced Pseudo Inverse Method (축소 의사역행렬과 영역분할 기반 축소모델 구축 기법 연구)

  • Kim, Hyun-Gi;Cho, Meang-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2009.04a
    • /
    • pp.139-145
    • /
    • 2009
  • Reduction scheme is remarkably useful in the case requiring the repeated calculation procedure. Recently, the efficiency of the reduction scheme has been improved by combining scheme of sub-domain method. But, when the global domain is partitioned into a few sub-domains, sub-domains without constraints can be produced. it is needed to extract the ritz vector from each sub-domain to construct the reduced system of each sub-domain. it is easy to extract the ritz vector from sub-domain with constraint. on the other hand, pseudo inverse method should be employed to extract the ritz vector from sub-domain without constraint. generally, the pseudo inverse takes a large number of computing time to obtain a reduced system of a sub-domain without boundary condition. This trouble can be overcome by the reduced pseudo inverse scheme which proposed in this study. This scheme is based on the static condensation that is not related with selection of the primary degrees of freedom. Numerical examples demonstrate that present method saves computational cost effectively and predicts the accurate eigenvalues.

  • PDF

Reduction Method based on Sub-domain Structure using Reduced Pseudo Inverse Method (축소 의사역행렬을 이용한 영역분할 기반 축소모델 구축기법 연구)

  • Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.22 no.2
    • /
    • pp.173-179
    • /
    • 2009
  • Reduction scheme is remarkably useful in the case requiring the repeated calculation procedure. Recently, the efficiency of the reduction scheme has been improved by combining scheme of sub-domain method. But, when the global domain is partitioned into a few sub-domains, sub-domains without constraints can be produced. it is needed to extract the ritz vector from each sub-domain to construct the reduced system of each sub-domain. it is easy to extract the ritz vector from sub-domain with constraint. on the other hand, pseudo inverse method should be employed to extract the ritz vector from sub-domain without constraint. generally, the pseudo inverse takes a large number of computing time to obtain a reduced system of a sub-domain without boundary condition. This trouble can be overcome by the reduced pseudo inverse scheme which proposed in this study. This scheme is based on the static condensation that is not related with selection of the primary degrees of freedom. Numerical examples demonstrate that present method saves computational cost effectively. In addition, it is shown that the reduced system based on the proposed scheme predicts the accurate eigenvalues of global system.

Construction of the reduced system by two-level scheme and time integration in the reduced system under arbitrary loading (2단계 축소기법에 의한 축소시스템의 구성과 동하중에 의한 구조물의 동적 거동에 관한 연구)

  • Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Proceedings of the KSME Conference
    • /
    • 2004.11a
    • /
    • pp.453-458
    • /
    • 2004
  • This study proposes a new two-level condensation scheme for the construction of a reduced system. In the first step, the candidate area is selected for the construction of the reduced system by energy estimation in element-level. In the second step, primary degrees of freedom are selected by sequential elimination from the candidate degrees of freedom linked to the selected elements. Numerical examples demonstrate that the proposed method saves the computational cost effectively and provides a reduced system which predicts the eigenvalues accurately. Moreover, the well-constructed reduced system can present the reliable behavior of the structure under arbitrary dynamic loads comparing to that of global system. Time integration in a reduced system can save the computing time remarkably. Through a few numerical examples, the efficiency and reliability of the proposed scheme are verified.

  • PDF

Study on the Dynamic Analysis Based on the Reduced System (축소모델 기반 구조물의 동적해석 연구)

  • Kim, Hyung-Gi;Cho, Maeng-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.21 no.5
    • /
    • pp.439-450
    • /
    • 2008
  • In this study, the reduced system for the dynamic analysis is proposed and the selection criterion of the primary degrees of freedom is presented considering the relation between natural frequency and external loading frequency. A well-constructed reduced system can assure the accurate representation of the dynamic behavior under arbitrary dynamic loads. For selecting the primary degrees of freedom of the reduced system, we employ the robust two-level condensation scheme of which the reliability has been proven through previous study. In the numerical examples, the reliability of the dynamic analysis based on the reduced system is demonstrated through comparing with those of global system.

Study on the Efficient Dynamic System Condensation (동적 해석의 효율적 축소기법에 관한 연구)

  • Baek, Seung-Min;Kim, Ki-Ook;Cho, Maeng-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.20 no.3
    • /
    • pp.347-352
    • /
    • 2007
  • Eigenvalue reduction schemes approximate the lower eigenmodes that represent the global behavior of the structures. In the previous study, we proposed a two-level condensation scheme (TLCS) for the construction of a reduced system. In the first step, the selection of candidate elements by energy estimation, Rayleigh quotient, through Ritz vector calculation. In the second step, the primary degrees of freedom are selected by the sequential elimination method from the degrees of freedom connected to the candidate elements in the first step. In the present study, we propose TLCS combined with iterative improved reduced system (IIRS) to increase accuracy of the higher modes in the intermediate range. Also, it is possible to control the accuracy of the eigenvalues and eigenmodes of the reduced system. Finally, numerical examples demonstrate the performance of the proposed method.