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In, A, B and C corresponding to the main degrees of freedom for the nodes 20,23,25,28 and the horizontal displacement on the 3O; D, E and F are the main degrees of freedom for the nodes corresponding to 3,5,8,1 O and 13 on the level of displacement. A and D, B and E,puma speed cats, c,wholesale PUMA, and F, respectively, used in [4,5,7], [6] and the results of this method. It can be seen from the figure the following two conclusions: (1) in [4,5,7] and [6] the accuracy of the method rather, the latter slightly higher than the former, while the accuracy of the proposed method the highest. Number of iterations in the same conditions, the accuracy of this method over a variety of ways than the five to ten times higher; (2) different options on the main degrees of freedom reduced model accuracy greater impact, especially in the low reduced order model frequency bands, the details in this regard can be found in the text [4, lo]. It is worth noting that the actual coordinates of the finite element model for dynamic condensation, the following types of degrees of freedom usually have freedom of choice-based, they are: given displacement degrees of freedom; out loads of freedom; need to study degrees of freedom; test test mode} can reflect the degree of freedom structural dynamic characteristics of the DOF. Therefore, the choice of the main degree of freedom is often little Moreover, various existing Master degree of freedom selection methods are either ineffective or much computation. Vibration and Shock 18, i7 1998 Volume Ia) concluded the second phase of frequency 4 (c】 fourth-order frequency (b) third-order frequency (d】 fifth-order frequency of Figure 2 under different conditions, different methods and reduced-order model Comparing the accuracy of this system directly from the characteristics of the modified equation is derived to characterize the system master and slave degrees of freedom between the deformation equations of dynamic condensation matrix, and the corresponding iterative method and convergence conditions. with existing methods compared: the method of high precision, in the case of the same number of iterations, the precision of this method than in [4-7]} five to ten times higher because not all applications in each iteration Rayleigh-Ritz method, thus reducing the amount of iteration. References 1GuyanRL.ReductionofStiffnessandMassMatrices.AIAAJournal,P90X Workout Schedule, 1965,3 (2): 3802IronsB.StructuralEigenvalueProbems-EliminationofUnwantedVariables.AIAAJournal, 1965,3 (5) :961-9623GysinH. ComparisonExpansionMethodforFEModelingErrorLocalization.Proceedingofthe8thInterna-rionalModalAnalysisConference, Florence, Italy ,1990:195-2044SuarezLE, SinghMP.Dynamiccondensationmethodforstructuraleigenvalueanalysis.AIAAJournal. 1992,30 (4): 1O46-10545 Zu-Qing Qu. Zhi-Fang Fu. A high precision power Chi Polymerization. mechanical strength (Accepted) 6 STAFF. Improved Guyan- recurrence by Chi techniques. Computational Structural Mechanics and Applications,uggs nederland, 1996f13 (I): 9o a 947 Zu-Qing Qu, Zhi-Fang Fu. A beam-like structure of floating raft method of reduced order modeling. Marine Engineering, 1997 (5) 14 a l68BatheKJ . FiniteElementProceduresinEngineeringAnalysis.Prentice-Hall, Engle-woodCliffs, NJ (1987) 9OianY, DhattG.Anacce [teratedsubspacemethodforgeneralizedeigen-problems.ComputersandStruc.tures, 1995,54:1】 27-113410MattaKW.SelectionofDegreesofFreedomforDynamicAlalysis.JournalofPressureVesselTechno1ogy.1987.109 (1) 065 -69
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