DECIV - Departamento de Engenharia Civil

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On the use of pseudo-forces to consider initial conditions in 3D time- and frequency-domain acoustic analysis.
(2006) Martins, Cláudio José; Carrer, José Antonio Marques; Mansur, Webe João; Araújo, Francisco Célio de
This work is mainly concerned with a general strategy, based on well known concepts of classical mechanics, for taking into account initial conditions in frequency-domain (FD) and time-domain (TD) analyses. A general approach, extended here to three-dimensional applications, is presented. Special problems associated with analyses through Discrete-Fourier-Transform (DFT) algorithms, as those occurring in consequence of a non-correct choice of extended period or those connected with aliasing phenomenon, are also discussed. Furthermore, an alternative starting procedure for time-marching schemes (in TD analyses) is proposed. At the end of the paper, to validate the proposed techniques and to demonstrate their generality, two- and three-dimensional problems with non-homogeneous initial conditions are solved through frequency- and time-domain approaches by employing the Finite Element Method (FEM). Numerical results are compared with existing analytical solutions.