• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.10a
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• pp.151-158
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• 1997

The main concern of numerical dynamic analysis of large structures is to find an acceptable solution with fewer mode shapes and less computational efforts. component mode method utilizes substructure technique to reduce the degrss of freedom but have a disadvantage to not consider the dynamic characteristics of loads. Ritz Vector method consider the load characteristics but requires many integrations and errors are accumulated. In this study, to prove the effectiveness of component mode method, Lanczos algorithm are introduced. To prove the effectiveness of this method, example structures areanalyzed and the results are compared with SAP90.

• Computational Structural Engineering
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• v.9 no.2
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• pp.115-120
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• 1996

The main concern of numerical dynamic analysis of large structures is to find an acceptable solution with fewer mode shapes and less computational efforts. Component mode method utilizes substructure technique to reduce the degree of freedom but have a disadvantage to not consider the dynamic characteristics of loads. Ritz Vector method consider the load characteristics but requires many integrations and errors are accumulated. In this study, to improve the effectiveness of component mode method, Lanczos algorithm is introduced. To prove the effectiveness of this method, example structure are analyzed and the results are compared with SAP90.

• Journal of KSNVE
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• v.6 no.1
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• pp.97-106
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• 1996

This paper presents systematic study of the experimental application of a free-interfaced component mode synthesis method. In the free-interfaced component mode synthesis method, an error the to truncated higher modes and neglected ineria loadings on a component from the connected component is inherent. Also, it is difficult to directly use experimental modal data in a modal synthesis method which links experimental model to finite-element model because of many inconsistencies between experimentally obtained and analytically obtained modal vectors and missing degrees-of-freedom (DOFs) such as rotational DOFs. In order to solve these problems, three methods, the first one based on attaching auxiliary weights to the connection points, the second one utillizing the normalization of experimental modal vector, and the third one generating smoothed and expanded experimental mode shapes, are studied in this paper. Finally, the study is illustrated for a flat-plate structure by using simulated and measured experimental data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.716-725
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• 2005

The method of substructure synthesis o. component mode synthesis(CMS) provides an effective means of dynamic analysis of very large and/or complex structures. In this study, residual dynamic flexibility attachment modes in hybrid component mode synthesis are considered for the purpose of exactly compensating the effect of higher order truncated modes. Following this way, the analysis accuracy of the synthesized structure can be improved effectively with less computational effort. In order to show the accuracy and effectiveness of the proposed hybrid component mode synthesis(HCMS), numerical experiments were carried out for the models of a clamped-clamped beam. The results verified the effectiveness of the proposed method.

• 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.

• Journal of KSNVE
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• v.9 no.2
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• pp.401-408
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• 1999

A method is presented for the vibration analysis of steam turbine-generator rotor system based on the component mode synthesis method. The motion of each component of the system is described by superposing constraint mode associated with boundary coordinates and constrained normal modes associated with internal coordinates. This method using real fixed-interface modes allows for significant reduction in system model size while retaining the essential dynamic characteristics of the lower modes. The capability of this method is demonstrated in the natural frequency and unbalance response analysis of the steam turbine-generator rotor system in which the dynamics of the pedestal is considered. The results by the present method are compared with finite element method and trnasfer matrix method in terms of the accuracy and computing time.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.177-184
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• 1997

The Component Mode Synthesis Method for the -vibration analysis can be applied to the large-scaled structures, which have difficulty in modeling because of their intricate shapes and boundary conditions and need much time in computational calculations. This paper uses the Component Mode Synthesis Method to analyze the free vibration for the steel box bridge having the large number of D.O.F as an example of the large structural system. By comparing the CMS method to the other method (FEM), this paper proves the accuracy of the solution in techniques and the efficiency in time.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.184-191
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• 1997

A method, termed as the substructural sensitivity synthesis method, which utilizes the computational merits of the component mode synthesis technique is proposed to calculate design sensitivity of modal parameters of substructurally combined structures. In this method, the sensitivity analysis is combined with component mode synthesis thchnique. thus the degrees of freedom of a combined structure can be dramatically reduced. Free-interface mode method including the residual attachment modes among the component mode synthesis methods is used to calculate the modal sensitivity of the combined structure. For the design sensitivities of modal properties of structure, the Nelson's method, which is exact solving method is used. It is shown that the modal sensitivities of the entire structure can be obtained by synthesizing the substructural modal data, and the sensitivities of the modal data about the design variables of modifiable substructure. Using the proposed method, the final degrees of freedom of entire structure can be remarkably reduced to calculate the modal parameter sensitivities. With a structure composed of beams and plates, as an example, the sensitivities of the eigenvalues and eigenvectors obtained by this proposed method were compared with the exact solutions in terms of accuracy.

• Journal of KSNVE
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• v.3 no.1
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• pp.77-82
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• 1993

In general, the dynamic analysis with FEM(Finite Element Method) of large structures requires large computer memory space and long computational time. For the purpose of economical dynamic analysis of large structures, most of engineers want to use an efficient solution algorithm. This paper reports the modified CMS(Component Mode Synthesis) method which uses more efficient algorithm than the classical CMS method. In this paper, it is shown that Ritz vector sets can play the role of normal mode vector sets of substurctures in the CMS algorithm. The modified CMS method has good convergence performance compared with that of the classical CMS method.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.65-74
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• 1994

Various substructure synthesis methods, such as component mode synthesis, building block analysis and reduced impedance method, are studied for the determination of vibration characteristics of plate problems. Comparisons are made for each methods in terms of accuracy and computational efficiency. Following conclusions are made from the results of computer simulations and experiments. i) The computation time of component mode synthesis is much shorter than that of whole structure analysis. The natural frequencies of lower modes obtained from component mode synthesis are almost same as those obtained from whole structure analysis, but in higher modes the differences between those two methods are increases. ii) The transfer function obtained from building block analysis is same as that obtained from the finite element method. iii) Same transfer functions can be obtained by the reduced impedance method. The computation time of reduced impedance mathod is shorter that that of general finite element method, but for the solutions in broad frequency band it requires long calculation time.