On the spurious solution in complex envelope displacement analysis

Complex envelope displacement analysis seems to be a promising approach to analyze high-frequency structural problems and is expected to be useful to study structural-acoustic coupled problems. However. in the original derivation of the method it was shown the presence of a troublesome spurious solution consisting of a high wavenumber component that would make the envelope approach inefficient. The elimination of this term is quite simple for one-dimensional systems but, in view of more complex developments, the problem deserves a serious investigation to explain the origin of this contribution and to introduce a simple and general approach to cancel this term in more general applications. In the present paper both these aspects are carefully considered and successfully developed.