The Convergence of the Iterated IRS Method

MI Friswell (University of Wales Swansea), SD Garvey & JET Penny (Aston University)

Journal of Sound and Vibration, Vol. 211, No. 1, March 1998, pp. 123-132


Static or Guyan reduction is widely used to reduce the number of degrees of freedom in a finite element model but it is exact only at zero frequency. The Improved Reduced System (IRS) method makes some allowance for the inertia terms and produces a reduced model which more accurately estimates the modal model of the full system. The IRS method may be extended to produce an iterative algorithm for the reduction transformation. It has already been shown this reduced model reproduces a subset of the modal model of the full system if the algorithm converges. This paper proves that the iterated IRS method converges. It is also shown that the lower modes converge more quickly than the higher modes and that the master co-ordinates should be chosen to give an accurate static reduction.

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Link to paper using doi:10.1006/jsvi.1997.1368

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