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Why another solver? 
Recently the availability of automated multilevel substructuring (AMLS) has enabled frequency response analyses to very high frequencies, using very large FE models and many modes. However, modeling damping appropriately for such analyses can make modal frequency response problems very expensive to solve. This is because modal damping matrices are diagonal only for certain idealized types of damping. In general, modeling damping more accurately results in modal damping matrices that are fully populated rather than diagonal. Then the modal frequency response solution ordinarily requires a matrix factorization at each frequency. The time required for each factorization is proportional to the cube of the number of modes, so analyses up to high frequencies, for which many modes are required, become extremely expensive. FastFRS (fast frequency response solver) addresses this issue by performing only one numerical operation whose cost is proportional to the cube of the number of modes, rather than one such operation at each response frequency. Fortunately, the solver obtains an exact, direct solution, rather than an approximation for which the user specifies a cutoff frequency, a convergence tolerance, or some other parameter requiring special expertise. As a result, the user does not need special instructions to use FastFRS. FRF Solution method
Example for FEM trimmed body model analysis
 Hard-/Software Requirements
Software: MSC.Nastran MD.Nastran NX Nastran MSC.Nastran is a proprietary product of MSC.Software Corporation. MD.Nastran is a proprietary product of MSC.Software Corporation. NX Nastran is a proprietary product of UGS Corporation. Platforms: Red Hat and Suse Linux64 IBM AIX HP-UX |
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