An iterative system equivalent reduction expansion process for extraction of high frequency response from reduced order finite element model

An iterative system equivalent reduction expansion process (SEREP) is proposed for extraction of high frequency response from a reduced-order model (ROM) under frequency band-limited excitation. Various model order reduction methods are discussed. To alleviate the present drawback of the SEREP, which requires computation of full system modal matrix, an iterative method based on Sturm sequence check is proposed. The method uses eigenvalue separation properties on the excitation frequency band to identify the optimal number of the eigenpairs required to capture the accurate response. The basic steps for numerical implementation are given. Numerical results are presented to validate the predicted response. Comparison is also made to explain the reasons for the instability of the ROM based on dynamic condensation to capture the high frequency dynamics. Case studies are carried out to demonstrate the effect of the chosen frequency band for response extraction. Also, it is shown that accurate results are obtained while using the proposed method when the chosen frequency band encompass the excitation frequency band.