Effects of modal truncation errors on transmitted dynamic power estimates in discretely joined component assemblies

In an earlier paper [J. Acoust. Soc. Am. 97, 2855–2865 (1995)], the authors proposed a new formulation based on modal synthesis methods for computing the mechanical power transmitted among components in vibrating assemblies. The formulation is exact if all component modes are included in the analysis, but errors may be introduced if incomplete sets of component modes are used. The effects of such modal truncation errors are examined in this paper. A new approach for determining truncation errors in assembly modal properties obtained from modal synthesis formulations is developed and applied, which reveals that the authors’ original formulation is susceptible to truncation errors. A modified formulation is developed which retains the advantages of the original, but yields more accurate results over a particular frequency range when small subsets of component modes are used. An example involving the flexural vibration of a beam is examined using both formulations. The example verifies the improved accuracy ...