The Transient Response of Structures Using Asymptotic Modal Analysis

Abstract

The transient response of a structure is predicted using an asymptotic modal approximation of the classical modal solution. The method is aimed at estimating the impulse response problem for high frequency regimes where typical numerical methods (e.g., finite elements) are impractical. As an example, the response of a thin elastic panel is modeled in a frequency range that includes a sufficient number of modes. Both impulsive and arbitrary forms of excitation are considered. It is shown that the asymptotic modal analysis yields an excellent estimate of both the local displacement near the excitation location and of the spatially averaged transient response of the panel for moderate time spans after the excitation is applied. Furthermore, as this approach does not require that the mode shapes or natural frequencies of the structure to be calculated, it is an extremely efficient technique.