A high-order approach for modelling transient wave propagation problems using the scaled boundary finite element method

A high-order time-domain approach for wave propagation in bounded and unbounded domains is proposed. It is based on the scaled boundary FEM, which excels in modelling unbounded domains and singularities. The dynamic stiffness matrices of bounded and unbounded domains are expressed as continued-fraction expansions, which leads to accurate results with only about three terms per wavelength. An improved continued-fraction approach for bounded domains is proposed, which yields numerically more robust time-domain formulations. The coefficient matrices of the corresponding continued-fraction expansion are determined recursively. The resulting solution is suitable for systems with many DOFs as it converges over the whole frequency range, even for high orders of expansion. A scheme for coupling the proposed improved high-order time-domain formulation for bounded domains with a high-order transmitting boundary suggested previously is also proposed. In the time-domain, the coupled model corresponds to equations of motion with symmetric, banded and frequency-independent coefficient matrices, which can be solved efficiently using standard time-integration schemes. Numerical examples for modal and time-domain analysis are presented to demonstrate the increased robustness, efficiency and accuracy of the proposed method. Copyright (c) 2013 John Wiley & Sons, Ltd.