A Shifted Iterative method of Dynamic Condensation for Finite　Element Models
Qu Zuqing  Hua Hongxin  Fu Zhifang
（Shanghai Jiaotong University 200030)

Abstract:  Based on the general inverse technique of matrices, an iterative method of dynamic condensation of finite element models with considering shifting frequency is presented in this paper. The constraint equation of the dynamic condensation matrix, which relates the deformations of the master and slave degrees of freedom, is directly derived from the original eigen equation at first. Then an iterative scheme and convergent criterion for the constraint equation is proposed. In order to reduce the computational work of solving the general inverse of matrix, an alternative approach is given. Comparing all the iterative schemes proposed in
the past, the present method has two main advantages. One is that the convergenceis much higher. The other is that the dynamic characteristics of the condensed system can close to that of any frequency range of original full model by changing the shifting value. Numerical examples demonstrate that the proposed method is feasible.
Keywords: finite element modeling, dynamic analysis, dynamic condensation, model reduction, general inverse.